TW202043146A - SiOC structure and composition for negative electrode using same, negative electrode, and secondary battery - Google Patents

Abstract

The present disclosure relates to an SiOC structure that includes (A) at least one silicon-based fine particle and (B) an SiOC coating layer containing at least Si (silicon), O (oxygen), and C (carbon) as constituent elements. The at least one silicon-based fine particle is covered by the SiOC coating layer, the BET specific surface area is 20 m2/g or less, and the cumulative 10% particle size (D10), cumulative 50% particle size (D50), and cumulative 90% particle size (D90) obtained by a laser diffraction/scattering particle size distribution measurement method satisfy the conditions 1 nm ≤ D50 ≤ 990 [mu]m and D90/D10 ≤ 13.0.

Description

Silicon oxycarbide structure, negative electrode composition, negative electrode, secondary battery, method for manufacturing silicon oxycarbide structure, and method for manufacturing negative electrode composition

The present invention relates to a silicon oxycarbide (SiOC) structure and a negative electrode composition, negative electrode and secondary battery using the same.

In various electronic equipment or communication equipment, as well as hybrid vehicles and other eco-cars, secondary batteries are used as driving power sources. As this type of secondary battery, it is mainly promoted to use lithium intercalation compounds that release lithium ions from the interlayers for positive electrode materials, and carbonaceous materials that can absorb and release lithium ions between the layers between the crystal planes during charge and discharge ( For example, graphite, etc.) are used in the development of various lithium-ion batteries for anode materials, and they are also put into practical use.

Under the background described above, in recent years, with the rapid spread of various electronic equipment, communication equipment, and hybrid vehicles, etc., as a driving power source for these equipment, there is a strong demand for higher development capacity and cycle characteristics. Or a secondary battery with improved battery characteristics such as discharge rate characteristics. In order to realize such a high-performance secondary battery, research and development with particular attention to negative electrode active materials are continuing, and the following technologies are known, for example.

For example, Patent Document 1 discloses a SiOC composite material obtained by physically mixing various polysilsesquioxanes and silicon particles, and heating the resulting mixture under prescribed conditions, and combining The SiOC composite material is used as a negative electrode of a negative electrode active material and a lithium ion battery. Patent Document 1 shows that if the negative electrode active material is used, the battery capacity and cycle durability can be improved in a battery cycle test. Furthermore, Patent Document 1 describes that in the disclosed SiOC composite material, silicon particles are embedded in a SiOC matrix derived from polysilsesquioxane, so-called "embedding" of the silicon particles in the SiOC matrix. As mentioned above, it refers to the structure realized by the physical mixing of polysilsesquioxane and silicon particles, that is, it can be understood as a structure in which silicon particles are only dispersed in the SiOC matrix.

Furthermore, Patent Document 2 discloses a negative electrode material including composite particles that are coated with ceramics on the entire surface or part of inorganic particles capable of absorbing and desorbing lithium ions. In more detail, the anode material disclosed in Patent Document 2 is an anode material for a non-aqueous electrolyte secondary battery, and is characterized in that the inorganic particles contain at least one selected from the group consisting of Si, Sn, and Zn. As a constituent element, the ceramic includes an oxide, nitride or carbide containing at least one element selected from the group consisting of Si, Ti, Al, and Zr. Patent Document 2 suggests that the negative electrode material having this configuration can reduce the volume change of the negative electrode material due to intercalation/deintercalation of lithium ions and the like, and can improve battery characteristics such as charge-discharge cycle characteristics. In Patent Document 2, as specific embodiments of the negative electrode material, several examples are described in which SiOC ceramics are used to coat inorganic fine particles containing Si and the like. In view of these examples, the negative electrode material disclosed in Patent Document 2 is Produced by the following manufacturing steps. That is, as a precursor organic molecule, phenyltrimethoxysilane is solized, and the inorganic fine particles are added to the resulting sol, and the hydrolysis reaction and polycondensation reaction are carried out to gel and form a massive gel. . By heating the bulk gel, the one converted into SiOC ceramic is used as the negative electrode material. Therefore, it is considered that in the negative electrode material disclosed in Patent Document 2, the inorganic fine particles are maintained in a state dispersed in SiOC ceramics derived from bulk gel.

Furthermore, Patent Document 3 discloses silicon composite particles obtained by sintering fine particles of silicon, silicon alloy, or silicon oxide with an organosilicon compound or a mixture thereof, and a non-aqueous electrolyte using the silicon composite particles. Anode material for secondary battery. The silicon composite particles disclosed in Patent Document 3 are characterized in that a silicon-based inorganic compound formed by sintering the organosilicon compound or a mixture thereof becomes a binder, in which silicon or a silicon alloy is dispersed. It is made of fine particles, and has a structure with voids in the particles. Patent Document 3 shows that if such a silicon composite particle is used as a negative electrode material, good cycle characteristics can be obtained. Specifically, the silicon composite particles disclosed in Patent Document 3 harden a mixture of silicon fine particles and a curable silicone composition containing various organosilicon compounds such as silicone compounds, and heat-treat the resulting mass. The obtained silicon composite is crushed. Therefore, regarding the negative electrode material disclosed in Patent Document 3, it is also considered that fine particles such as silicon are dispersed in the silicon composite.

Furthermore, Patent Document 4 discloses a negative electrode active material for a non-aqueous electrolyte secondary battery comprising a ceramic composite material in which metallic silicon and SiC are dispersed in SiOC ceramics. In more detail, the ceramic composite material disclosed in Patent Document 4 is characterized in that the peak intensity of the (111) plane-wound rays of the metal silicon in the X-ray diffraction using CuKα characteristic X-rays is set to b1, When the peak intensity of the (111) plane-wound ray of the SiC is set to b2, the ratio represented by b1/b2 and the density when compressed at 30 MPa are within predetermined numerical ranges. Patent Document 4 suggests that a secondary battery using a negative electrode active material containing such a ceramic composite material exhibits excellent initial efficiency, charge and discharge capacity, and cycle characteristics. Specifically, the ceramic composite material disclosed in Patent Document 4 is manufactured through the following manufacturing steps. That is, metal silicon particles are added to a carbon precursor solution in which novolak-type phenol resin is dissolved as a carbon source, and then tetraethoxysilane is added, and the polymer obtained by polymerizing the silane compound is cured by heating And the step of solvent removal treatment is sintered, and the ceramic composite material thus obtained is used as a negative electrode active material. Therefore, the ceramic composite material disclosed in Patent Document 4 is also obtained by dispersing particles of metallic silicon and SiC in SiOC ceramics.

Furthermore, Patent Document 5 is a Chinese Patent Application Publication Gazette, which is considered to disclose a nanosilica energy storage material having a core-shell structure as shown in each figure and a lithium ion battery containing the storage material. Specifically, the nanosilica energy storage material disclosed in Patent Document 5 can be considered to be a composite material obtained by the following method, namely, surface treatment of Si nano particles with a silane coupling agent, and a variety of organosilane compounds The surface-treated Si nano-particles are uniformly dispersed in the hydrolyzate, and the polycondensate obtained by polycondensing the hydrolyzate is coated with petroleum pitch and then sintered. According to the core-shell structure shown in each figure, the composite material can also be considered to include: a core of silicon nanoparticle, an intermediate layer derived from polymerizable organosiloxane, and a petroleum-derived layer located outside the intermediate layer. As for the shell of pitch, in Patent Document 5, although a scanning electron microscope (Scanning Electron Microscope, SEM) photograph showing the appearance of the composite material actually obtained (Figure 5 of the document) is published, it does not show any As a result of investigating its internal structure, there are many unclear points as to whether the core-shell structure as shown in the schematic diagram of FIG. 3 or FIG. 4 of the document is actually formed. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2018-502029 [Patent Document 2] Japanese Patent Laid-Open No. 2004-335335 [Patent Document 3] Japanese Patent Laid-Open No. 2005-310759 [Patent Document 4] Japanese Patent Laid-Open No. 2017-62974 [Patent Document 5] Chinese Patent Application Publication No. 107464926

[The problem to be solved by the invention] As described above, with the miniaturization of various electronic equipment, communication equipment, and the rapid spread of hybrid vehicles, etc., secondary batteries used as driving power sources for these equipment have been required to include capacity retention and coulomb efficiency. Various battery characteristics including various cycle characteristics are further improved, and research and development focusing on negative electrode active materials are particularly active.

Under such circumstances, the inventors of the present invention have also developed various negative electrode active materials represented by the negative electrode active material described in Patent Document 1. Especially for negative electrode active materials using SiOC composite materials, they have also repeatedly researched suitable for industrial scale. Mass production, focusing on various manufacturing steps. Among them, the inventors of the present invention have advanced the development of various SiOC composite materials obtained by sintering composite materials of silicon nanoparticle and polysilsesquioxane in the use of negative electrode active materials. In the development of this type of SiOC composite material, the inventors discovered that if the functional silane compound, which becomes the starting material for polysilsesquioxane synthesis, is hydrolyzed under static conditions instead of under stirring conditions, then In the step of polycondensation of the hydrolysate in the presence of silicon-based nanoparticles to synthesize polysilsesquioxane, the silicon-based nanoparticles are uniformly coated with polysilsesquioxane with a smoother outer surface Ground-coated silicon-based nanoparticle/polysilsesquioxane composite. The uniform coating structure of this coating on the silicon-based nanoparticle can be maintained after it is converted into a SiOC structure by heat treatment . Furthermore, the inventors of the present invention found that if a SiOC structure having such a structure is used as a negative electrode active material to produce a lithium ion secondary battery, battery characteristics such as cycle capacity retention rate and average coulombic efficiency are improved. That is, the present invention was completed based on the above findings, and the subject of the present invention is to provide a material for a negative electrode active material that can achieve good capacity retention and coulombic efficiency, a method of manufacturing the material, and use of the material as a negative electrode Active material negative electrode composition, negative electrode and secondary battery. [Means to solve the problem]

In order to solve the problem, according to the present invention, the following can be provided.

[1] A SiOC structure comprising: (A) at least one silicon-based fine particle; and (B) a SiOC coating containing at least Si (silicon), O (oxygen) and C (carbon) as constituent elements, said at least A silicon-based fine particle is covered by the SiOC coating, and the Brunauer-Emmett-Teller (BET) specific surface area of the SiOC structure is 20 m ² /g or less, and the particle size is dispersed by laser diffraction The cumulative 10% particle size (D10), cumulative 50% particle size (D50), and cumulative 90% particle size (D90) obtained by the distribution measurement method satisfy the conditions of 1 nm≦D50≦990 μm and D90/D10≦13.0.

[2] The SiOC structure according to [1], wherein the at least one silicon-based fine particle and the SiOC coating are chemically bonded to each other. [3] The SiOC structure according to [1] or [2], wherein the BET specific surface area is 15 m ² /g or less. [4] The SiOC structure according to any one of [1] to [3], wherein the BET specific surface area is 10 m ² /g or less. [5] The SiOC structure according to any one of [1] to [4], wherein the cumulative 50% particle size (D50) satisfies the condition of 500 nm≦D50≦100 μm.

[6] The SiOC structure according to any one of [1] to [5], wherein the cumulative 50% particle size (D50) satisfies the condition of 1 μm≦D50≦20 μm. [7] The SiOC structure according to any one of [1] to [6], wherein the cumulative 10% particle size (D10) and the cumulative 90% particle size (D90) satisfy 2.0≦D90/D10 The condition of ≦12.0. [8] The SiOC structure according to any one of [1] to [7], wherein the cumulative 10% particle size (D10) and the cumulative 90% particle size (D90) satisfy 2.5≦D90/D10 The condition of ≦8.0. [9] The SiOC structure according to any one of [1] to [8], wherein the at least one silicon-based fine particle has a volume-based average particle diameter in the range of 1 nm to 2 μm.

[10] The SiOC structure according to any one of [1] to [9], wherein the at least one silicon-based fine particle has a volume-based average particle diameter in the range of 10 nm to 500 nm. [11] The SiOC structure according to any one of [1] to [10], wherein the at least one silicon-based fine particle is completely covered by the SiOC coating to form a plurality of secondary particles, The two secondary particles are connected to each other via the SiOC coating. [12] The SiOC structure according to any one of [1] to [11], which contains Si in the range of 50% to 90% by mass and 5% to 35% by mass based on the total mass of the SiOC structure O in the range of% and C in the range of 2% by mass to 35% by mass are main constituent elements. [13] A composition for a negative electrode containing the SiOC structure according to any one of [1] to [12] as a negative electrode active material. [14] The negative electrode composition according to [13], further containing a carbon-based conductive auxiliary agent and/or a binder.

[15] A negative electrode comprising the negative electrode composition according to [13] or [14]. [16] A secondary battery including at least one negative electrode as described in [15]. [17] The secondary battery according to [16], which is a lithium ion secondary battery.

[18] A method of manufacturing a SiOC structure, comprising: (p) hydrolyzing the silane compound represented by the general formula (I), and then performing polycondensation in the presence of silicon-based fine particles, thereby generating a silicon-containing compound containing at least one A silicon-based microparticle/silicon-containing polymer composite formed by coating at least one silicon-based microparticle with a polymer coating; and (q) treating the silicon-based microparticle/silicon-containing polymer composite under a non-oxidizing atmosphere Heat treatment is performed to convert into the SiOC structure as described in any one of [1] to [10], R ¹ _n SiX ¹ _4-n … (I) (where R ¹ is hydrogen, hydroxyl or A substituted or unsubstituted hydrocarbon having 1 to 45 carbon atoms, and in the hydrocarbon having 1 to 45 carbon atoms, any hydrogen can be substituted by halogen, and any -CH ₂ -can be -O-, -CH=CH -, cycloalkylene or cycloalkenylene substitution, X ¹ is halogen, alkyloxy or acetoxy having 1 to 6 carbons, and when there are multiple R ¹ and X ¹ respectively, they are mutually Independent, n is an integer from 0 to 3).

[19] The method according to [18], wherein the silane compound represented by the general formula (I) is a silane compound represented by the following general formula (II): R ¹⁰ Si(R ⁷ )(R ⁸ ) (R ⁹ ) …(II) (In the formula, R ⁷ , R ⁸ and R ⁹ are each independently hydrogen, halogen, hydroxyl, or alkyloxy group having 1 to 4 carbon atoms, and R ^{10 is} selected from the group consisting of 1 to 45 carbon atoms The substituted or unsubstituted alkyl group, the substituted or unsubstituted aryl group, and the substituted or unsubstituted arylalkyl group, and the alkyl group having 1 to 45 carbon atoms Among them, any hydrogen can be substituted by halogen, and any -CH ₂ -can be substituted by -O-, -CH=CH-, cycloalkylene or cycloalkenylene, in the case of substituted or unsubstituted arylalkane In the alkylene group, any hydrogen may be substituted by halogen, and any -CH ₂ -may be substituted by -O-, -CH=CH-, cycloalkylene or cycloalkenylene).

（式中，R¹ 及R⁴ 分別獨立地選自由碳數1～45的經取代或未經取代的烷基、經取代或未經取代的芳基、及經取代或未經取代的芳基烷基所組成的群組中，於碳數1～45的烷基中，任意的氫可經鹵素取代，任意的-CH₂ -可經-O-、-CH=CH-、伸環烷基或伸環烯基取代，於經取代或未經取代的芳基烷基中的伸烷基中，任意的氫可經鹵素取代，任意的-CH₂ -可經-O-、-CH=CH-或伸環烷基取代； R² 、R³ 、R⁵ 及R⁶ 分別獨立地選自由氫、碳數1～45的經取代或未經取代的烷基、經取代或未經取代的芳基、及經取代或未經取代的芳基烷基所組成的群組中，於碳數1～45的烷基中，任意的氫可經鹵素取代，任意的-CH₂ -可經-O-、-CH=CH-、伸環烷基、伸環烯基或-SiR¹ ₂ -取代，於經取代或未經取代的芳基烷基中的伸烷基中，任意的氫可經鹵素取代，任意的-CH₂ -可經-O-、-CH=CH-、伸環烷基、伸環烯基或-SiR¹ ₂ -取代；n表示1以上的整數）。[20] The method according to [18] or [19], wherein the silicon-containing polymer comprises at least one selected from the group consisting of polysilsesquioxanes, the polysilsesquioxanes They respectively have the polysilsesquioxane structure represented by the following general formula (III), general formula (IV), general formula (V) and general formula (VI):

(In the formula, R ¹ and R ⁴ are each independently selected from a substituted or unsubstituted alkyl group having 1 to 45 carbon atoms, a substituted or unsubstituted aryl group, and a substituted or unsubstituted aryl group In the group of alkyl groups, in the alkyl group with 1 to 45 carbon atoms, any hydrogen can be substituted by halogen, and any -CH ₂ -can be -O-, -CH=CH-, cycloalkylene Or cycloalkenylene substitution. In the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen can be replaced by halogen, and any -CH ₂ -can be -O-, -CH=CH -Or cycloalkylene substitution; R ² , R ³ , R ⁵ and R ⁶ are each independently selected from hydrogen, substituted or unsubstituted alkyl having 1 to 45 carbons, and substituted or unsubstituted aryl In the group consisting of substituted or unsubstituted arylalkyl groups, in the alkyl group with 1 to 45 carbon atoms, any hydrogen may be substituted by halogen, and any -CH ₂ -may be -O -, -CH=CH-, cycloalkylene, cycloalkenylene or -SiR ¹ ₂ -substituted, in the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen may be halogenated Substitution, any -CH ₂ -may be substituted by -O-, -CH=CH-, cycloalkylene, cycloalkenylene or -SiR ¹ ₂ -; n represents an integer of 1 or more).

[21] The method according to any one of [18] to [20], wherein the following (p-1) to (p-3) are performed in step (p): (P-1) Add the silane compound represented by the general formula (I) to an acidic solution with a pH of 3-6 to hydrolyze the silane compound; (P-2) Add silicon-based fine particles or its dispersion to the reaction solution obtained in step (p-1); (P-3) Add a predetermined amount of acid or its solution to the mixed liquid obtained in step (p-2), and adjust the pH of the mixed liquid to 2 or less, and make the mixed liquid for a predetermined time And it is allowed to stand at a predetermined temperature, whereby the polycondensation of the silane compound is performed, and the silicon-based fine particles/silicon-containing polymer composite is produced.

[22] The method according to any one of [18] to [21], wherein the following steps (p-1') to (p-3') are performed in step (p): (P-1') In an acidic solution with a pH of 3-6, the silane compound represented by the general formula (I) is added step by step under stirring conditions, and the silane compound is made to be used for a predetermined period of time under stirring conditions. Hydrolysis at specified temperature; (P-2') Adding silicon-based fine particles or its dispersion to the reaction solution obtained in step (p-1'), so that the silicon-based fine particles or its dispersion are uniformly dispersed in the reaction solution; (P-3') Add a predetermined amount of acid or its solution to the mixed liquid obtained in step (p-2'), and adjust the pH of the mixed liquid to 2 or less, and then make the mixed liquid It is allowed to stand for a predetermined time and at a predetermined temperature, whereby the polycondensation of the silane compound proceeds to produce the silicon-based fine particles/silicon-containing polymer composite.

[23] The method according to any one of [18] to [22], wherein in step (p), an acid or its aqueous solution is used as an acid catalyst. [24] The method according to any one of [18] to [23], wherein in the general formula (I), n=1, R ¹ is a hydrocarbon having 1 to 10 carbons, and there are three X ¹ Each is independently a halogen, an alkyloxy group having 1 to 6 carbon atoms, or an acetoxy group. [25] The method according to any one of [18] to [24], wherein in step (p), the silane compound represented by the general formula (I) comprises selected from methyltrimethoxysilane and benzene At least one silane compound in the group consisting of trimethoxysilane. [26] The method according to any one of [18] to [25], wherein the non-oxidizing gas atmosphere in step (q) is an atmosphere containing an inert gas. [27] The method according to any one of [18] to [26], wherein the non-oxidizing gas atmosphere in step (q) is an atmosphere containing nitrogen and/or argon.

[28] The method according to any one of [18] to [27], wherein in step (q), the silicon-based fine particles/silicon-containing polymer composite is heated to a temperature of 400°C to 1800°C The temperature within the range is heated at this temperature for a time ranging from 30 minutes to 10 hours. [29] A method of manufacturing a composition for a negative electrode, comprising: obtaining the composition for a negative electrode by using the SiOC structure as described in any one of [1] to [12] as a negative electrode active material. [Effects of the invention]

According to the present invention, a good cycle capacity maintenance rate and coulomb efficiency can be achieved in a secondary battery.

Hereinafter, the present invention will be explained in more detail. <SiOC structure> According to the first embodiment of the present invention, there is provided a SiOC structure including: (A) at least one silicon-based fine particle; and (B) containing at least Si (silicon), O (oxygen), and C (carbon) ) SiOC coating as a constituent element, the at least one silicon-based fine particle is covered by the SiOC coating, and the SiOC structure has a BET specific surface area of 20 m ² /g or less, and is diffused by laser diffraction The cumulative 10% particle size (D10), cumulative 50% particle size (D50), and cumulative 90% particle size (D90) obtained by the particle size distribution measurement method satisfy the conditions of 1 nm≦D50≦990 μm and D90/D10≦13.0. Hereinafter, the SiOC structure of the present invention will be described in detail.

(Silicon-based fine particles) The SiOC structure of the first embodiment of the present invention includes at least one silicon-based fine particle. In the present invention, "silicon-based fine particles" is a concept including silicon fine particles that essentially only contain silicon, and fine particles containing compounds containing silicon in their atomic composition (such as silicon dioxide and silicon-containing metal compounds).

The particle diameter (volume-based average particle diameter) of the silicon-based fine particles can be used as long as it is in the range of the nanometer or micrometer scale. Although not particularly limited, for example, silicon-based fine particles having a volume-based average particle diameter in the range of 1 nm to 2 μm can be used. Considering the use of the SiOC structure as the negative electrode material of the secondary battery, the volume-based average particle diameter (average particle diameter) of the silicon-based fine particles is preferably, for example, 10 nm to 500 nm, preferably 10 nm to 200 nm, More preferably, it is in the range of 20 nm to 100 nm.

(SiOC coating) Furthermore, the SiOC structure of the first embodiment of the present invention includes a SiOC coating layer covering the at least one silicon-based fine particle. Here, as described above, the SiOC coating contains at least Si (silicon), O (oxygen), and C (carbon) as constituent elements, but in addition to these, the inclusion of other elements is not excluded. In the present invention, the so-called SiOC coating is not particularly limited. Specifically, as described later, as long as it contains at least one silicon-containing polymer and is coated with silicon-based fine particles, it is ceramized by a predetermined heat treatment. Who can.

(Silic particles are coated with SiOC coating) In addition, one of the features of the SiOC structure of the present invention is that "the at least one silicon-based fine particle is completely covered by the SiOC coating layer."

Here, as an embodiment of such "coating", as long as the SiOC structure has at least one structural part in which the silicon-based fine particles are completely covered by the SiOC coating, it is not necessary that all the silicon-based fine particles contained in the SiOC structure are The SiOC coating is completely covered. That is, in the present invention, as an embodiment in which silicon-based fine particles are coated with a SiOC coating, specifically, the following embodiments can be cited. (I) The embodiment in which the silicon-based fine particles contained in the SiOC structure are completely covered by the SiOC coating; and (Ii) At least one of the silicon-based fine particles contained in the SiOC structure is completely covered by the SiOC coating, while the remaining silicon-based fine particles are partially covered by the SiOC coating, and a part of the surface of the remaining silicon-based fine particles is exposed from the SiOC coating The implementation form. In addition, in the SiOC structure of the present invention, it is also envisaged that when a plurality of silicon-based fine particles are contained, two or more of the plurality of silicon-based fine particles are in direct and physical contact with each other, and the two or more silicon particles in contact in this way This is an embodiment in which the fine particles are completely covered by the SiOC coating.

Furthermore, the morphology of the silicon-based fine particles coated with the SiOC coating can be confirmed by electron microscope observation such as SEM. As the morphology of the SiOC structure observed in this manner, specifically, the morphology observed in the SEM photographs shown in FIGS. 2(a), 3(a), and 3(b) can be cited. In more detail, in the SiOC structure of the present invention, it is preferable to use the SiOC coating as observed in the SEM photos of Figure 2(a) and Figure 3(a) and Figure 3(b). To coat at least one silicon-based fine particle to form a plurality of secondary particles, which are connected to each other through the SiOC coating. The reason is that when the SiOC structure shows a form in which silicon-based fine particles are covered with a SiOC coating and are connected to each other via the SiOC coating, the SiOC structure exhibits excellent performance as an active material for negative electrodes. The improvement of the capacity retention rate and the coulombic efficiency can be expected in secondary batteries.

In addition, in the present invention, the silicon-based particles and the SiOC coating are preferably chemically bonded to each other. The SiOC structure in which the silicon-based fine particles and the SiOC coating are chemically bonded to each other as described above can be specifically manufactured by the method described below. In more detail, by using an acidic catalyst to hydrolyze a predetermined functional silane compound and perform polycondensation in the presence of silicon-based fine particles, a coating containing a silicon-containing polymer is formed around the silicon-based fine particles. This obtains a composite of silicon-based particles/silicon-containing polymer. According to the polycondensation reaction of the silane compound in the presence of such silicon-based fine particles, the surface of the silicon-based fine particles and the silicon-containing polymer formed by the polycondensation reaction appear in the formed silicon-based fine particles/silicon-containing polymer composite. The state of the chemical bond. Then, by heating the silicon-based fine particles/silicon-containing polymer composite under prescribed conditions, the coating is ceramized and converted into a SiOC structure. The surface of the silicon-based fine particles and the silicon-containing polymer The chemically bonded structure can also be maintained after the silicon-based microparticle/silicon-containing polymer composite is converted into an SiOC structure. That is, in the SiOC structure, the silicon-based fine particles and the SiOC coating are connected by a chemical skeleton that is generated along with the formation of the silicon-containing polymer. Examples of such chemical skeletons include chemical skeletons containing Si-O-C, Si-O, Si-O-Si, and the like.

(BET specific surface area of SiOC structure) As described above, the BET specific surface area of the SiOC structure of the present invention needs to be 20 m ² /g or less. The lower limit of the BET specific surface area of the SiOC structure is not particularly limited. For example, it may be 1 m ² /g, that is, the BET specific surface area may be in the range of 1 m ² /g to 20 m ² /g. As described above, in the SiOC structure of the present invention, at least one silicon-based fine particle is completely covered by the SiOC coating. More specifically, this feature is related to that the SiOC structure of the present invention can maintain a smooth and uniform surface as a whole without surface roughness even after being subjected to physical treatment such as crushing treatment. From the viewpoint of maintaining such a smooth and uniform surface more reliably, the BET specific surface area of the SiOC structure is preferably 15 m ² /g or less, more preferably 10 m ² /g or less, and is further used as the BET specific surface area The range of is preferably 1 m ² /g to 15 m ² /g, more preferably 1 m ² /g to 10 m ² /g. Furthermore, the BET specific surface area refers to the specific surface area obtained by the Brunauer-Emmett-Teller (BET) method known to those skilled in the art.

(The particle diameter of the SiOC structure) In the SiOC structure of the present invention, as described above, the cumulative 10% particle size (D10), cumulative 50% particle size (D50) and cumulative 90% particle size obtained by the laser diffraction scattering particle size distribution measurement method The diameter (D90) satisfies the conditions of 1 nm≦D50≦990 μm and D90/D10≦13.0.

Here, the cumulative 10% particle size (D10), the cumulative 50% particle size (D50, the so-called median particle size), and the cumulative 90% particle size (D90) are known technologies in the field of particle size distribution measurement technology. The particle size measured and calculated by the laser diffraction scattering particle size distribution method. These particle diameters are not particularly limited, and can be measured using a commercially available laser diffraction/scattering particle size distribution measuring device (for example, MT-3300EX II manufactured by MicrotracBEL).

In the SiOC structure of the present invention, the cumulative 50% particle size (D50) is preferably 500 nm≦D50≦100 μm, more preferably 500 nm≦D50≦50 μm, and even more preferably 500 nm≦D50≦ 20 μm, as appropriate, the conditions of 1 μm≦D50≦20 μm, 2 μm≦D50≦18 μm, 2 μm≦D50≦17 μm, 3 μm≦D50≦16 μm, 4 μm≦D50≦16 μm can also be satisfied.

In addition, in the SiOC structure of the present invention, the cumulative 50% particle size (D50) and the cumulative 90% particle size (D90) are preferably 2.0≦D90/D10≦12.0, more preferably 2.0≦D90/D10≦11.0, More preferably 2.0≦D90/D10≦10.0, particularly preferably 2.0≦D90/D10≦9.5, for example, 2.0≦D90/D10≦9.0, 2.0≦D90/D10≦8.5, 2.5≦D90/D10≦8.0 , 2.5≦D90/D10≦7.0, 3.0≦D90/D10≦7.0, and optionally 3.0≦D90/D10≦6.0.

In the SiOC structure of the present invention, the cumulative 10% particle size (D10), the cumulative 50% particle size (D50, the so-called median particle size), and the cumulative 90% particle size (D90) satisfy the above-mentioned conditions In this case, it shows a relatively uniform particle size distribution, and when the SiOC structure is used as a negative electrode material, good battery characteristics can be achieved.

Furthermore, in the SiOC structure of the present invention, as long as the cumulative 10% particle size (D10), the cumulative 50% particle size (D50, the so-called median particle size), and the cumulative 90% particle size (D90) satisfy the conditions , There is no particular limitation, and the volume-based average particle diameter in the particle size distribution represented by the frequency (%) may be in the range of 1 nm to 990 μm. In the case of being used as a negative electrode active material in a secondary battery, the average particle diameter may be preferably 500 nm to 100 μm, more preferably 1 μm to 50 μm, and even more preferably 1 μm to 20 μm. It is preferably in the range of 1 μm to 15 μm. Furthermore, the average particle diameter is the same as the cumulative 10% particle size (D10), the cumulative 50% particle size (D50, the so-called median particle size), and the cumulative 90% particle size (D90), which can be achieved by using laser Diffraction/scattering type particle size distribution measuring device using laser diffraction scattering method for measurement.

(Elemental composition of SiOC structure) The elemental composition of the SiOC structure of the present invention is not particularly limited. The SiOC structure may be based on the total mass of the SiOC structure, and may contain, for example, Si in the range of 50% to 90% by mass, and the range of 5% to 35% by mass. O and C in the range of 2% to 35% by mass as the main constituent elements. Furthermore, in some embodiments, the SiOC structure of the present invention may be based on the total mass of the SiOC structure, containing Si in the range of 60% to 90% by mass, O in the range of 10% to 35% by mass, and C in the range of 2% by mass to 20% by mass as the main constituent element, in another embodiment, Si in the range of 65% to 82% by mass, O in the range of 15% to 35% by mass And C in the range of 3% by mass to 15% by mass as the main constituent element. Furthermore, in addition to Si, O, and C, the SiOC structure of the present invention may of course contain other elements as constituent elements.

<The manufacturing method of the SiOC structure> According to the second embodiment of the present invention, a method of manufacturing the SiOC structure (hereinafter, sometimes referred to as "the manufacturing method of the SiOC structure") is provided, including: (p) will be determined by the general formula (I) The silane compound represented by (I) is hydrolyzed and then polycondensed in the presence of silicon-based fine particles, thereby generating silicon-based fine particles/containing at least one silicon-based fine particles covered by a coating containing at least one silicon-containing polymer A silicon polymer composite; and (q) heat processing the silicon-based fine particles/silicon-containing polymer composite under a non-oxidizing gas atmosphere, thereby converting it into the SiOC structure, R ¹ _n SiX ¹ _4-n …(I) (In the formula, R ¹ is hydrogen, a hydroxyl group or a substituted or unsubstituted hydrocarbon with 1 to 45 carbons, and among the hydrocarbons with 1 to 45 carbons, any hydrogen may be halogenated Substitution, any -CH ₂ -can be substituted by -O-, -CH=CH-, cycloalkylene or cycloalkenylene, X ¹ is halogen, alkyloxy with 1 to 6 carbons or acetyloxy When a plurality of R ¹ and X ¹ respectively exist, they are independent of each other, and n is an integer of 0 to 3). Hereinafter, the manufacturing method of the SiOC structure of the present invention will be described in detail.

(Hydrolyzable silane compound) In the manufacturing method of the SiOC structure of the present invention, first, as described above, in step (p), as the hydrolyzable silane compound, the silane compound represented by the general formula (I) is hydrolyzed, and the resulting hydrolyzed The substance is polycondensed in the presence of silicon-based microparticles, thereby forming a silicon-based microparticle/silicon-containing polymer composite formed by coating at least one silicon-based microparticle with a coating containing at least one silicon-containing polymer.

As a preferred embodiment, the following embodiments can be adopted: In the general formula (I), n=1, R ¹ is a hydrocarbon with 1 to 10 carbons, and there are three X ^1s each independently being a halogen and a carbon number. 1 to 6 alkyloxy or acetoxy.

Furthermore, in some embodiments, as the silane compound represented by the general formula (I), the silane compound represented by the following general formula (II) may also be used. R ¹⁰ Si(R ⁷ )(R ⁸ )(R ⁹ ) …(II) (wherein R ⁷ , R ⁸ and R ⁹ are each independently hydrogen, halogen, hydroxy, or alkyl oxygen having 1 to 4 carbon atoms Group, R ^{10 is} selected from the group consisting of substituted or unsubstituted alkyl groups having 1 to 45 carbon atoms, substituted or unsubstituted aryl groups, and substituted or unsubstituted arylalkyl groups , And in an alkyl group with 1 to 45 carbon atoms, any hydrogen can be substituted by halogen, and any -CH ₂ -can be substituted by -O-, -CH=CH-, cycloalkylene or cycloalkenylene, In the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen can be substituted by halogen, and any -CH ₂ -can be -O-, -CH=CH-, cycloalkylene or Cycloalkenylene substitution) Here, in the general formula (II), the substituent of the substituted alkyl group is preferably a halogen, an alkyl group having 1 to 10 carbons, and an alkene having 2 to 10 carbons. Group, C1-C5 alkoxy, phenyl or naphthyl and other aromatic groups.

As the silane compound represented by the general formula (I), more specifically, organotrichlorosilanes or organotrialkoxysilanes are mainly cited. In more detail, examples include: methyl trimethoxy silane, methyl triethoxy silane, ethyl trimethoxy silane, ethyl triethoxy silane, trimethoxy (propyl) silane, n-butyl Triethoxysilane, isobutyltrimethoxysilane, n-pentyltriethoxysilane, n-hexyltrimethoxysilane, isooctyltriethoxysilane, decyltrimethoxysilane, methyl dimethyl Oxyoxyethoxysilane, methyldiethoxymethoxysilane, 2-chloroethyltriethoxysilane, methoxymethyltriethoxysilane, methylthiomethyltriethoxysilane , Methoxycarbonylmethyltriethoxysilane, 2-propenyloxyethyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane and other substituted or unsubstituted alkanes Trialkoxysilane compounds; Phenyltrimethoxysilane, 4-methoxyphenyltrimethoxysilane, 2-chlorophenyltrimethoxysilane, phenyltriethoxysilane, 2-methoxysilane Substituted or unsubstituted aryl trialkoxysilane compounds such as phenyl triethoxy silane, phenyl dimethoxy ethoxy silane, phenyl diethoxy methoxy silane, etc. In particular, the silane compound represented by the general formula (I) preferably includes at least one silane compound selected from the group consisting of methyltrimethoxysilane and phenyltrimethoxysilane. Furthermore, in addition to the above-mentioned organotrichlorosilane or organotrialkoxysilane, other types of silane compounds such as dialkoxydialkylsilane can also be used; or instead of the aforementioned organotrichlorosilane or For organotrialkoxysilanes, other types of silane compounds such as dialkoxydialkylsilanes are used.

Next, the conditions for the hydrolysis and polycondensation of the silane compound in step (p) will be described in detail. (Solvent) The solvent constituting the reaction liquid in the step (p) is not particularly limited as long as it is capable of proceeding the hydrolysis/polycondensation of the silane compound. Specifically, in order to assist the hydrolysis of the silane compound, water may be included. In addition to water, examples include alcohols such as methanol, ethanol, 2-propanol, ethers such as diethyl ether, acetone, or methyl ethyl ketone. Organic solvents such as ketones, hexane, dimethyl formamide (DMF), toluene and other aromatic hydrocarbon solvents. These may be used individually by 1 type, or may mix and use 2 or more types.

(Acid catalyst) In the present invention, the acid catalyst is not an essential component, but it can be used as appropriate in order to appropriately control the hydrolysis and/or polycondensation reaction. As the acid catalyst, either organic acid or inorganic acid can be used. Specifically, the organic acid can be exemplified by formic acid, acetic acid, propionic acid, oxalic acid, and citric acid, and the inorganic acid can be exemplified by hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. Among these, it is preferable to use hydrochloric acid and/or acetic acid in terms of easy control of the hydrolysis reaction and the subsequent polycondensation reaction, low cost, and easy handling after the reaction.

In addition, in the case of using a silane halide such as trichlorosilane as the silane compound, an acidic aqueous solution is formed in the presence of water to achieve "acidic conditions" under which the silane compound can be hydrolyzed and polycondensed. Therefore, in the case of using the silane halide as described above, even if an acidic catalyst is not added to the reaction system, the hydrolysis and polycondensation reaction will proceed, so there is no need to add a catalyst. That is, in this case, in step (p), the acid catalyst is not an essential element as described above.

(Silicon-based fine particles) Regarding silicon-based fine particles, as described above, it is a concept that includes silicon fine particles that essentially only contain silicon, and fine particles that contain silicon in their atomic composition (such as silicon dioxide and silicon-containing metal compounds). The concept can be used without particular limitation. As the silicon-based fine particles, silicon fine particles that substantially contain only silicon can be preferably used. In particular, since various silicon powders are commercially available, these are preferably used. In addition, the conditions such as the average particle diameter are as described above.

(Conditions for hydrolysis and polycondensation) Next, the reaction conditions of the hydrolysis and polycondensation in step (p) will be described.

The ratio of the silane compound in the reaction solution is not particularly limited. Relative to 100 parts by mass of the reaction solution, it is, for example, about 0.1 parts by mass to about 30 parts by mass, preferably about 0.1 parts by mass to about 25 parts by mass, and more preferably It is about 0.5 parts by mass to about 20 parts by mass. As long as this range is used as a reference, the ratio of the atomic composition to be realized in the SiOC structure to be finally produced can be appropriately set together with the addition ratio of the silicon-based fine particles.

The addition ratio of the silicon-based fine particles is also not particularly limited, as long as it considers the element composition ratio to be achieved in the SiOC structure to be finally produced, and the desired battery characteristics, and can be appropriately set together with the silane compound. With respect to 100 parts by mass of the silane compound, the addition ratio of the silicon-based fine particles is, for example, about 0.1 parts by mass to about 70 parts by mass, preferably about 1.0 parts by mass to about 60.0 parts by mass, more preferably about 5.0 parts by mass to about 55 parts by mass, particularly preferably about 10 parts by mass to about 50 parts by mass.

The ratio of the solvent contained in the reaction solution during the hydrolysis or polycondensation is not particularly limited as long as the hydrolysis or polycondensation reaction is appropriately carried out, and it may be, for example, about 50 parts by mass to 100 parts by mass of the silane compound. It is about 2500 parts by mass, preferably about 100 parts by mass to about 2400 parts by mass, more preferably about 100 parts by mass to about 2300 parts by mass, particularly preferably about 150 parts by mass to about 2200 parts by mass. Furthermore, in a specific embodiment, the ratio of the solvent contained in the reaction liquid during the hydrolysis reaction may be, for example, about 50 parts by mass to about 1500 parts by mass relative to 100 parts by mass of the silane compound. It is about 100 parts by mass to about 1000 parts by mass, more preferably about 150 parts by mass to about 800 parts by mass, particularly preferably about 150 parts by mass to about 600 parts by mass, relative to 100 parts by mass of the silane compound, the polycondensation reaction The ratio of the solvent contained in the reaction solution at that time is set, for example, from about 400 parts by mass to about 2500 parts by mass, preferably from about 500 parts by mass to about 2400 parts by mass, more preferably from about 550 parts by mass to about 2300 parts by mass, It is particularly preferably about 600 parts by mass to about 2,200 parts by mass, and optionally about 700 parts by mass to about 2000 parts by mass. In addition, in the case of adopting the ratio range, as described above, only water may be used as a solvent, or a mixed solvent of water and other solvents (alcohol, organic solvent, etc.) may also be used.

When an acid catalyst is added during the hydrolysis or polycondensation reaction, the ratio of the acid catalyst may be appropriately adjusted so as to obtain the desired hydrolysis or polycondensation reaction, and is not particularly limited. 100 parts by mass, for example, about 0.02 parts by mass to about 15 parts by mass, preferably about 0.02 parts by mass to about 10 parts by mass, more preferably about 0.02 parts by mass to about 8 parts by mass, as appropriate, about 0.04 parts by mass to about About 7 parts by mass, about 0.08 parts by mass to about 6 parts by mass.

The order or method of addition of each component is not particularly limited. Generally speaking, for example, a solvent (a catalyst solution obtained by mixing a solvent and a catalyst) can be put into the reaction vessel, and the atmosphere in the reaction vessel can be replaced with After a prescribed gas atmosphere (such as nitrogen, argon, helium and other inert gases), add (dropwise) the silane compound to the solution in the reaction vessel under stirring, while stirring the reaction solution or in a static state , The hydrolysis and/or polycondensation reaction is carried out at the specified reaction temperature and reaction time. Furthermore, regarding the order of addition of each component and the method of the hydrolysis/polycondensation reaction, preferred embodiments are described in detail below.

Furthermore, the reaction temperature of hydrolysis and/or polycondensation is not particularly limited, and is, for example, about -20°C to about 80°C, preferably about 0°C to about 70°C, and optionally about 0°C to about 40°C, about 10°C. °C to about 30°C, for example, room temperature (for example, room temperature: about 20°C to 25°C). The reaction time is also not particularly limited, and for example, about 0.5 hour to about 100 hours, and about 1 hour to about 80 hours, and about 1 hour to about 6 hours as appropriate.

The pH of the reaction solution is not particularly limited as long as the hydrolysis and polycondensation reaction of the silane compound proceed satisfactorily. The pH of the reaction solution is usually in the range of 0.8 to 12, depending on the specific silane compound or The shape or properties of the desired organosilicon compound (polysilsesquioxane) product can be selected. Here, the pH of the reaction liquid can be adjusted using the acid containing the acidic catalyst.

In more detail, in step (p), the hydrolysis reaction of the silane compound is first performed under specified conditions, and then the polycondensation reaction is performed in the presence of silicon-based fine particles, whereby the silicon specified in the present invention can be synthesized It is a fine particle/silicon-containing polymer composite. In more detail, in some embodiments, the following (p-1) to (p-3) may also be performed in step (p).

(P-1) Add the silane compound represented by the general formula (I) to an acidic solution with a pH of 3-6 to hydrolyze the silane compound; (P-2) Add silicon-based fine particles or its dispersion to the reaction solution obtained in step (p-1); (P-3) Add a prescribed amount of acid or its solution to the mixed liquid obtained in step (p-2), and adjust the pH of the mixed liquid to 2 or less (1.5 or less as the case may be, such as 0.9 ~2.0, 0.9~1.5), and the mixed solution is allowed to stand still at a predetermined temperature for a predetermined time, whereby the polycondensation of the silane compound is carried out to produce the silicon-based fine particles/silicon-containing polymer composite.

In addition, in a specific embodiment, the following (p-1') to (p-3') may also be performed in step (p).

(P-1') In an acidic solution with a pH of 3-6, the silane compound represented by the general formula (I) is added step by step under stirring conditions, and the silane compound is made to be used for a predetermined period of time under stirring conditions. Hydrolysis at specified temperature; (P-2') Adding silicon-based fine particles or its dispersion to the reaction solution obtained in step (p-1'), so that the silicon-based fine particles or its dispersion are uniformly dispersed in the reaction solution; (P-3') Add a predetermined amount of acid or its solution to the mixed liquid obtained in step (p-2'), and adjust the pH of the mixed liquid to 2 or less (1.5 or less as the case may be, For example, 0.9-2.0, 0.9-1.5), and then, the mixed solution is allowed to stand still for a predetermined time and at a predetermined temperature, whereby the polycondensation of the silane compound is performed, and the silicon-based fine particles/silicon-containing polymer composite is produced.

Here, in a specific embodiment, as the "acidic solution with a pH of 3 to 6" in step (p-1) or step (p-1'), for example, an acetic acid solution of a predetermined concentration (preferably Aqueous acetic acid), as the range of the acetic acid concentration, for example, a concentration of about 0.001 M to about 0.1 M, and preferably a concentration of about 0.005 M to about 0.09 M can be cited. Furthermore, in a specific embodiment, as the "predetermined amount of acid or its solution" in step (p-3) or step (p-3'), for example, a hydrochloric acid solution of a predetermined concentration (preferably an aqueous hydrochloric acid solution) can be used. ), the concentration range of hydrochloric acid is not particularly limited. For example, a range of about 10% by mass to about 40% by mass, preferably about 20% by mass to about 40% by mass can be cited.

Hereinafter, steps (p-1) to (p-3) and steps (p-1') to (p-3') are described in detail, and a more preferable embodiment is shown.

In step (p-1) or step (p-1'), more specifically, a hydrolyzate can be generated by hydrolyzing the silane compound in an acidic aqueous medium. The hydrolysis reaction of the silane compound can be, for example, The silane compound is added dropwise to an acidic aqueous medium. Here, in step (p-1) or step (p-1'), in order to fully perform the desired hydrolysis, acidic conditions are adopted in which the hydrolysis reaction rate is higher than the polycondensation reaction rate and the hydrolysis reaction proceeds preferentially. The pH range that realizes such acidic conditions varies depending on the type of the silane compound used as the raw material, but it can usually be adjusted to pH 3-6, preferably pH 4-6. The reason is that if the pH of the reaction liquid is in such a range, the produced polymer will not be precipitated in the reaction liquid, and a good hydrolysis reaction can be realized. Furthermore, the degree of acidity will affect the balance of hydrolyzate production, reaction time, or the amount of partial condensate and the number of condensation, etc., but it will not have a major impact on the particle size.

Furthermore, as the acid that can be used when preparing the medium in the acidic pH range, as long as the acid catalyst is used, the hydrolysis reaction and subsequent polycondensation reaction can be easily controlled, and the acquisition or pH adjustment is also easy In general, it is best to use acetic acid. For example, in the case of using a dilute aqueous acetic acid solution as the acidic aqueous medium, the pH is about 5.0 to 5.8.

Then, in step (p-2) or step (p-2'), more specifically, silicon-based fine particles (preferably preliminarily) are added to the reaction solution containing the hydrolysate obtained in step (p-1) The prepared dispersion liquid of silicon-based fine particles), the resulting mixed solution is stirred, for example, for 10 seconds to 2 hours, preferably for about 1 minute to 1.5 hours.

Then, in step (p-3) or step (p-3'), a prescribed amount of acid or acid solution is added to the mixed solution obtained in step (p-2) or step (p-2'), After stirring the mixed solution for, for example, 1 second to 30 seconds, preferably 1 second to 15 seconds or so, it is allowed to stand without stirring, for example, 2 hours to 36 hours, preferably 4 hours to 24 hours, more preferably 4 hours to In about 12 hours, the hydrolyzate produced in step (p-1) is polycondensed in the presence of silicon-based fine particles to obtain a silicon-based fine particle/silicon-containing polymer composite having the structure specified in the present invention.

As described above, in step (p-3) or step (p-3'), the hydrolysate of the silane compound is polycondensed in the presence of silicon-based fine particles without stirring the reaction liquid and in a static state As the reaction progresses, a silicon-based microparticle/silicon-containing polymer composite (more specifically, the structure shown in Figure 1) is formed by uniformly covering at least one silicon-based microparticle with a coating containing a silicon-containing polymer. As the final product, a SiOC structure having the structure specified in the present invention is indeed manufactured.

As described above, the silicon-based fine particles/silicon-containing polymer composite produced in step (p) includes as a constituent: a coating layer containing a silicon-containing polymer. Here, the silicon-containing polymer is produced by hydrolysis and polycondensation of the predetermined hydrolyzable silane compound. In the present invention, the silicon-containing polymer may more specifically include at least one polymer selected from the group consisting of polycarbosilane, polysiloxane, polysiloxane, and polysilsesquioxane.

Generally, polycarbosilane contains at least one of the structural units represented by the following (1) to (3). (1) (R ¹ R ² SiCH ₂ ) (2) (R ¹ Si(CH ₂ ) _1.5 ) (3) (R ¹ R ² R ³ Si(CH ₂ ) _0.5 ) Here, R ¹ , R ² and R ^{3 is} each independently hydrogen or a hydrocarbon having 1 to 20 carbons (preferably 1 to 6 carbons). Examples of hydrocarbons include alkyl groups such as methyl, ethyl, propyl, and butyl; alkenyl groups such as vinyl and allyl; and aryl groups such as phenyl. In addition, the hydrocarbon may be substituted with heteroatoms such as silicon, nitrogen, or boron at any position. In addition, polycarbosilane can be substituted with various metal groups such as aluminum, chromium, and titanium at any position. Various compounds and their synthesis processes are known in the prior art for such metal-substituted polycarbosilanes. Therefore, in the manufacturing method of the SiOC structure of the present invention, these known synthesis processes can be combined.

In the present invention, as the polysilane that can be used as the silicon-containing polymer, for example, various polysilanes containing at least one structural unit shown in the following (4) to (6) can be cited.

(4) (R ¹ R ² R ³ Si) (5) (R ¹ R ² Si) (6) (R ³ Si) Here, R ¹ , R ² and R ^{3 are} as described above. In a specific embodiment, the polysilane as a silicon-containing polymer may be selected from (Me ₂ Si), (PhMeSi), (MeSi), (PhSi), (ViSi), (PhHSi), (MeHSi), At least one structural unit in the group consisting of (MeViSi), (Ph ₂ Si), (PhViSi) and (Me ₃ Si). Furthermore, Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group. In addition, polysilane may be substituted with any metal group, that is, it may contain a predetermined number of repeating units of any metal-Si. As examples of preferable metal bases, aluminum, chromium and titanium can be cited.

In the present invention, as the polysiloxane that can be used as the silicon-containing polymer, for example, various polysiloxanes including the structural unit shown in (7) below can be cited. (7) (R ¹ R ² R ³ SiO _0.5 ) _w (R ⁴ R ⁵ SiO) _x (R ⁶ SiO _1.5 ) _y (SiO _4/2 ) _z Here, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently hydrogen or a hydrocarbon having 1 to 20 carbons (preferably 1 to 6 carbons) as described for R ¹ , R ² and R ³ . In addition, w, x, y, and z are the molar ratios of the respective constituent elements indicated respectively, w=0 to 0.8, x=0.3 to 1, y=0 to 0.9, z=0 to 0.9, and w+x +y+z=1.

Specific examples of siloxane units that can be used in the present invention include (MeSiO _1.5 ), (PhSiO _1.5 ), (ViSiO _1.5 ), (HSiO _1.5 ), (PhMeSiO), (MeHSiO), (PhViSiO), ( MeViSiO), (Ph ₂ SiO), (Me ₂ SiO), (Me ₃ SiO _0.5 ) (Ph ₂ ViSiO _0.5 ), (Ph ₂ HSiO _0.5 ), (H ₂ ViSiO _0.5 ), (Me ₂ ViSiO _0.5 ), ( SiO _4/2 ) and so on. Furthermore, Me represents a methyl group, Ph represents a phenyl group, and Vi represents a vinyl group.

In the present invention, polysilsesquioxanes that can be used as silicon-containing polymers mainly include polysilsesquioxanes containing (RSiO _3/2 ) _X units. Here, R is a saturated or unsaturated, linear, branched or cyclic hydrocarbon group, for example -C _n H _2n+1 (n is an integer in the range of 1 to 20), more specifically, For methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, Octadecyl and eicosyl; can also be aryl, especially phenyl or tolyl; can also be cycloalkyl, specifically cyclobutyl, cyclopentyl or cyclohexyl; can also be alkene Group, especially vinyl or allyl; or aralkyl containing 2-phenylethyl or benzyl. R may contain heteroatoms, especially nitrogen or halogen, preferably R is methyl, ethyl, propyl or phenyl. R may also be a combination of two or more different groups. x is the number of repeating units, and is an integer of 1 or more, and can be, for example, an arbitrary integer selected from the range of 4 to 10,000.

In a preferred embodiment, the silicon-containing polymer as the main component of the coating layer covering the silicon-based fine particles contains polysilsesquioxane. In a more preferred embodiment, the silicon-containing polymer substantially contains polysilsesquioxane. Preferably, in step (p), at least one silicon-based fine particle is formed by coating silicon-based fine particle/silicon-containing polymer In a composite body, the coating includes a silicon-containing polymer containing polysilsesquioxane. The silicon-based microparticle/silicon-containing polymer composite of this structure can be made of any trifunctional organosilane (organotrialkoxysilane, organic Trichlorosilane, etc.) obtained by hydrolysis and polycondensation.

As polysilsesquioxanes, it can include trapezoidal polysilsesquioxanes, POSS (T ^R ₈ ) and other cage polysilsesquioxanes, incomplete cage polysilsesquioxanes and other types At least one of the group consisting of polysilsesquioxanes. Various types of polysilsesquioxanes and their synthesis methods are known, so these synthesis methods can be used in the present invention (Chemistry and Application Development of Silsesquioxane Materials, CMC Publication, 2013 Popular Edition Wait).

In more detail, in a specific embodiment, the silicon-containing polymer may include at least one selected from the group consisting of polysilsesquioxanes, the polysilsesquioxanes respectively having The polysilsesquioxane structure represented by the general formula (III), the general formula (IV), the general formula (V) and the general formula (VI).

In the formula, R ¹ and R ⁴ are each independently selected from a substituted or unsubstituted alkyl group having 1 to 45 carbon atoms, a substituted or unsubstituted aryl group, and a substituted or unsubstituted aryl alkyl group In the group formed by the group, in the alkyl group with 1 to 45 carbon atoms, any hydrogen can be substituted by halogen, and any -CH ₂ -can be -O-, -CH=CH-, cycloalkylene or Cycloalkenylene substitution. In the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen can be replaced by halogen, and any -CH ₂ -can be replaced by -O-, -CH=CH- Or cycloalkylene substitution; R ² , R ³ , R ⁵ and R ⁶ are each independently selected from a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 45 carbon atoms, and a substituted or unsubstituted aromatic group. In the group consisting of substituted or unsubstituted arylalkyl groups, in the alkyl group with 1 to 45 carbon atoms, any hydrogen may be substituted by halogen, and any -CH ₂ -may be -O -, -CH=CH-, cycloalkylene, cycloalkenylene or -SiR ¹ ₂ -substituted, in the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen may be halogenated Substitution, any -CH ₂ -may be substituted by -O-, -CH=CH-, cycloalkylene, cycloalkenylene or -SiR ¹ ₂ -; n represents an integer of 1 or more. In the present invention, "halogen" can be understood literally and means fluorine, chlorine, bromine, iodine, etc., among which fluorine or chlorine is preferred.

The manufacturing method of the SiOC structure of the present invention may further optionally include at least one of the following steps. (A) After the hydrolysis reaction and the polycondensation reaction produce a silicon-based fine particle/silicon-containing polymer composite, optionally filtration separation (such as pressure filtration), solid-liquid separation, solvent distillation removal, centrifugal separation or tilting, etc. In the method, the liquid component is separated and removed, and the obtained solid component is used as the heat-treated object to be tested in step (q). Regarding the separation method of such a solid component and a liquid, various general techniques are known to those skilled in the art, so these methods can be used appropriately. (B) Furthermore, the solid components obtained above are washed with water or organic solvent, and the organic solvent is distilled off and dried (drying under reduced pressure and/or heat drying).

Regarding the heat treatment conditions in the embodiment of step (q), it may be appropriately set in consideration of the type or capacity of the heat treatment device used, for example, it can be set at 0.5° C./min to 200° C./min in a non-oxidizing atmosphere. Minutes, preferably 0.5°C/minute to 100°C/minute, more preferably 1°C/minute to 50°C/minute, still more preferably 1°C/minute to 30°C/minute, particularly preferably 2°C/minute to Heating at a temperature increase rate of 10°C/min to a temperature in the range of 400°C to 1800°C, preferably 600°C to 1400°C, more preferably 900°C to 1300°C, and at this temperature for 5 minutes to 20 hours, The heat treatment is preferably performed in the range of 30 minutes to 10 hours, more preferably 1 hour to 8 hours. However, regarding the heat treatment conditions such as the heating rate, heat treatment temperature, and heating time, it is only necessary to consider the properties of the polysilsesquioxane used as a raw material, the physical properties of the desired SiOC structure, and other properties, productivity, or economy. The minimum necessary heat treatment conditions may be appropriately selected, and they are not particularly limited.

In addition, the "non-oxidizing gas atmosphere" of the present invention includes an inert gas atmosphere, a reducing atmosphere, and a mixed atmosphere using these atmospheres. Examples of the inert gas atmosphere include inert gases such as nitrogen, argon, and helium. These inert gases may be used alone or in combination of two or more. In addition, the inert gas may be used by general users, and is preferably of high purity specifications. The reducing atmosphere also includes an atmosphere containing a reducing gas such as hydrogen. For example, a mixed gas atmosphere of 2% by volume or more of hydrogen and inert gas can be cited. In addition, as a reducing atmosphere, a hydrogen atmosphere itself may be used as appropriate.

In addition, the non-oxidizing atmosphere is produced by replacing the atmosphere in the heat treatment furnace with the predetermined gas or supplying the predetermined gas into the furnace. When the gas is supplied into the heat treatment furnace, the gas flow rate may be appropriately adjusted to an appropriate range according to the specifications of the heat treatment furnace used (for example, the shape or size of the furnace), and is not particularly limited. It can be about 5% to 100% of the furnace content per minute, preferably about 5% to 30% per minute. More specifically, when a generally used vacuum purge tube furnace is used on a laboratory scale, the gas flow rate (purge amount) can be set to, for example, about 50 mL/min to 1 L/min. , Preferably about 100 mL/minute to 500 mL/minute. In addition, when manufacturing the SiOC structure of the present invention by using a heat treatment furnace with a furnace inner volume of about 40 L, the gas flow rate (purge amount) can be set to, for example, about 10 L/min to 15 L/min.

As heat treatment furnaces that can be used in step (q), in addition to vacuum-purge tube furnaces, for example, rotary kiln (rotary kiln) type, roller hearth kiln (roller hearth kiln) type, batch kiln (batch kiln type, pusher kiln type, mesh belt kiln type, carbon furnace, tunnel kiln type, shuttle kiln type, trolley lift kiln type, etc. Heat treatment furnace. Only one type of these heat treatment furnaces may be used, or two or more types may be combined. Furthermore, in the case of combining two or more types, the heat treatment furnaces may be connected in series or in parallel.

The manufacturing method of the SiOC structure of the present invention may further include additional steps such as crushing and/or classification of the SiOC structure obtained by the heat treatment of the step (q). The crushing method and classification method that can be used in these steps are not particularly limited. For example, various known methods can be adopted, and a mortar, various crushers, sieves, cyclone classification devices, etc. can be used.

<Composition for negative electrode and its manufacturing method> According to another embodiment of the present invention, a composition for a negative electrode is disclosed. The negative electrode composition includes the SiOC structure as a negative electrode active material. In addition, according to another embodiment of the present invention, a method of manufacturing the negative electrode composition is also disclosed. The method for producing the negative electrode composition includes obtaining the negative electrode composition by using the SiOC structure as a negative electrode active material.

The composition for a negative electrode of the present invention may further contain additional components such as a carbon-based conductive auxiliary agent and/or a binder described later.

Specific examples of carbon-based materials that function as carbon-based conductive additives include graphite, carbon black, fullerenes, carbon nanotubes, carbon nanofoam, pitch-based carbon fibers, polyacrylonitrile-based carbon fibers, and Carbon-based substances such as amorphous carbon. These carbon-based substances may be used alone, or a mixture of two or more kinds may be used.

As the binder that can be used in the present invention, as long as it can be used in secondary batteries, for example, carboxymethyl cellulose, polyacrylic acid, alginic acid, glucomannan, amylose, sucrose and their derivatives can be cited. In addition to the substance or polymer, and the respective alkali metal salt, polyimide resin or polyimide resin may be mentioned. These binders can be used alone or in mixture of two or more.

Furthermore, in addition to the binder, additives that can provide other functions such as improving the adhesion between the current collector and the negative electrode active material, improving the dispersibility of the negative electrode active material, and improving the conductivity of the binder itself, can also be added as necessary. Specific examples of such additives include styrene-butadiene rubber-based polymers, styrene-isoprene rubber-based polymers, and the like.

When the composition for a negative electrode of the present invention further contains additional components such as a carbon-based conductive aid and/or a binder as described above, the method for producing the composition for a negative electrode of the present invention may include the following step (r). Step (r): mixing the SiOC structure of the present invention with the additional component, or compounding or coating the additional component on the SiOC structure of the present invention.

As a specific method that can be used to achieve step (r), there can be mentioned a mechanical mixing method using various stirring bars or stirring blades, mechanical fusion, ball mills, vibration mills, etc., to make the The method for dispersing SiOC structure and carbon-based substances can preferably use a thin-film rotary high-speed mixer manufactured by Primix Co., Ltd. (Filmix (registered trademark) series ] Dispersion processing based on film rotation method that can be realized. In the method for producing the negative electrode composition of the present invention, these mechanical mixing methods or dispersion methods may be used alone to obtain the negative electrode composition, or multiple methods may be combined step by step to obtain the negative electrode composition.

For example, in step (r), the SiOC structure of the present invention and any carbon-based conductive auxiliary agent can be added in a predetermined amount to a binder aqueous solution with a concentration of about 1% to 5% by weight, and a stirrer can be used Or other mixers for mixing. Furthermore, to the obtained mixture, water may be further added as needed so that it may become a predetermined solid content concentration, and stirring may be continued to make a slurry-form composition, and this may be used as the composition for negative electrodes of this invention. In addition, the dispersion treatment based on the thin film rotation method may be applied to the slurry composition, and the resultant may be used as the negative electrode composition of the present invention.

Furthermore, in the arbitrarily selected step (r), the SiOC structure and the carbon-based substance may be mixed in an arbitrary ratio so as to obtain desired battery characteristics according to the purpose. Furthermore, the method of manufacturing the negative electrode composition of the present invention may precede the steps and optionally include the steps that can be included in the method of manufacturing the SiOC structure, and the embodiment including these arbitrary steps is also the same Those clearly disclosed in the manual.

＜Anode and its manufacturing method＞ According to another embodiment of the present invention, a negative electrode is disclosed. Furthermore, according to another embodiment of the present invention, a method of manufacturing a negative electrode is also disclosed. The negative electrode of the present invention is obtained by the method of manufacturing a negative electrode. The method includes: obtaining a negative electrode using the SiOC structure or the negative electrode composition. Examples of specific manufacturing steps are shown below.

Specifically, the negative electrode of the present invention is manufactured using the SiOC structure as the negative electrode active material, or the negative electrode composition containing the SiOC structure as the negative electrode active material. In more detail, for example, the negative electrode can be manufactured based on a method of molding the SiOC structure or the composition for a negative electrode into a certain shape, or a method of coating on a current collector such as copper foil. The method of forming the negative electrode may use any method without particular limitation, and various known methods can be used.

In more detail, for example, the pre-prepared negative electrode composition can be directly coated on a rod-shaped body or plate mainly composed of copper, nickel, stainless steel, etc., by a doctor blade method, a slurry casting method, a screen printing method, etc. Current collectors such as shaped bodies, foil-shaped bodies, and mesh bodies. Alternatively, the negative electrode composition may be separately cast on the support, and the negative electrode composition film formed on the support may be peeled off, and the peeled negative electrode composition film may be laminated on the current collector to form Negative electrode plate. In addition, the composition for the negative electrode coated on the current collector or the support may be air-dried or a drying treatment step performed at a predetermined temperature, and/or may be further subjected to pressing treatment or punching treatment as necessary The processing steps are implemented to obtain the final negative electrode body.

Furthermore, the method of manufacturing a negative electrode of the present invention may precede the steps and optionally include the steps that can be included in the method of manufacturing the SiOC structure and the method of manufacturing the negative electrode composition, and these embodiments are also It is clearly disclosed in this specification. In addition, the form of the negative electrode is only an example, and the form of the negative electrode is not limited to these, and it can of course be provided in other forms.

＜Secondary battery and its manufacturing method＞ According to still another embodiment of the present invention, a secondary battery is provided. Furthermore, according to another embodiment of the present invention, a method for manufacturing a secondary battery is also provided. The method includes manufacturing a secondary battery by using the negative electrode.

The secondary battery of the present invention includes at least one negative electrode of the present invention. As long as the secondary battery of the present invention includes at least one negative electrode of the present invention and functions as a secondary battery, other constituent members or structures are not particularly limited. More specifically, in addition to the negative electrode, each of at least one Positive electrode and separator (separator). In the case where the negative electrode and the positive electrode and the separator of the present invention include a plurality of each, the secondary battery of the present invention can be a laminate type in which these components are alternately laminated in the order of positive electrode/separator/negative electrode/separator The layered structure. Alternatively, a layered structure in which the positive electrode and the negative electrode are wound into a coil shape via a separator may also be adopted. In addition, the secondary battery of the present invention may include an electrolytic solution or a solid electrolyte.

Specifically, the secondary battery of the present invention is a secondary battery obtained by the method of manufacturing a secondary battery of the present invention. The secondary battery may be appropriately designed in consideration of the intended use, function, etc., and its configuration is not particularly limited, and the configuration of the existing secondary battery can be referred to, and the negative electrode of the present invention can be used to construct the secondary battery. In addition, the type of the secondary battery of the present invention is not particularly limited as long as the negative electrode can be applied, and examples include lithium ion secondary batteries and lithium ion polymer secondary batteries. As demonstrated in the following examples, these batteries can exhibit the desired effects of the present invention, and therefore can be described as particularly preferred embodiments. Hereinafter, the secondary battery of the present invention and its manufacturing method will be exemplified particularly with respect to an embodiment in the case of a lithium ion secondary battery.

First, a positive electrode active material capable of reversibly absorbing and releasing lithium ions, a conductive auxiliary agent, a binder, and a solvent are mixed to prepare a positive electrode active material composition. As with the negative electrode, the positive electrode active material composition is directly coated on the metal current collector and dried using various methods to prepare a positive electrode plate. It is also possible to separately cast the positive electrode active material composition on a support body, peel off the film formed on the support body, and laminate the film on a metal current collector to produce a positive electrode. The method of forming the positive electrode is not particularly limited, and various well-known methods can be used to form it.

As the positive electrode active material, lithium metal composite oxides generally used in the field of secondary batteries can be used. Examples include: lithium cobalt oxide, lithium nickel oxide, lithium manganate having a spinel structure, lithium cobalt manganese oxide, iron phosphate having an olivine structure, so-called ternary lithium metal composite oxide, and nickel-based lithium metal Composite oxides and so on. In addition, V ₂ O ₅ , TiS, MoS, etc., which are compounds capable of detaching and inserting lithium ions, can also be used.

A conductive assistant can also be added, which can be used by ordinary users in lithium ion batteries. It is preferably an electron conductive material that does not cause decomposition or deterioration in the manufactured battery. Specific examples include carbon black (acetylene black, etc.), graphite fine particles, vapor-grown carbon fiber, and combinations of two or more of these. In addition, as the binder, for example, vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene and the like Mixtures, styrene butadiene rubber-based polymers, etc., but are not limited to these. Moreover, as a solvent, N-methylpyrrolidone, acetone, water, etc. are mentioned, for example, but it is not limited to these. At this time, the contents of the positive electrode active material, the conductive auxiliary agent, the binder, and the solvent are not particularly limited, and can be appropriately selected based on the amounts generally used in lithium ion batteries.

As the separator between the positive electrode and the negative electrode, it is not particularly limited as long as it is used by general users in lithium ion batteries, and it may be appropriately selected in consideration of the desired use or function. It is preferable that the resistance to ion migration of the electrolyte is low, or the electrolyte is excellent in impregnation ability. Specifically, it is a material selected from glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene, polyimide, or a compound thereof, and may be in the form of non-woven fabric or woven fabric. More specifically, in the case of a lithium ion battery, it is preferable to use a coilable separator containing a material such as polyethylene and polypropylene, and in the case of a lithium ion polymer battery, use an organic electrolyte to impregnate Excellent separator.

As an electrolyte, you can use: propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl carbonate, dibutyl carbonate, Benzoonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, two Solvents such as methyl acetamide, dimethyl sulfide, dioxane, 1,2-dimethoxyethane, cyclobutane, dichloroethane, chlorobenzene, nitrobenzene or diethyl ether, or these In the mixed solvent of the solvent, it dissolves lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroantimonate, lithium hexafluoroarsenate, lithium perchlorate, lithium trifluoromethanesulfonate, Li(CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiN(C _x F _2x+1 SO ₂ )(C _y F _2y+1 SO ₂ ) (where x and y are natural numbers), LiCl, LiI A substance composed of one or a mixture of two or more of these in the electrolyte of a general lithium salt.

In addition, various non-aqueous electrolytes or solid electrolytes can be used instead of the electrolyte. For example, various ionic liquids to which lithium ions are added, pseudo-solid electrolytes in which ionic liquids are mixed with fine powders, lithium ion conductive solid electrolytes, and the like can be used.

Furthermore, in order to improve the charge-discharge cycle characteristics, a compound that promotes the formation of a stable coating on the surface of the negative electrode active material may be appropriately contained in the electrolyte solution. For example, the effective ones are vinylene carbonate (VC), fluorobenzene, cyclic fluorinated carbonate [fluoro ethylene carbonate (FEC), trifluoropropylene carbonate, TFPC), etc.], or chain fluorinated carbonate [trifluorodimethylcarbonate (TFDMC), trifluorodiethylcarbonate (TFDEC), trifluoroethylmethylcarbonate (trifluoroethylmethylcarbonate, TFEMC) and other fluorinated carbonates. Furthermore, the cyclic fluorinated carbonate and the chain fluorinated carbonate can also be used as a solvent like ethylene carbonate.

It is also possible to arrange a separator between the positive electrode plate and the negative electrode plate as described above to form a battery structure, and the battery structure can be wound or folded and placed in a cylindrical battery case or square shape After being put into the battery case, electrolyte is injected to complete the lithium ion battery. Alternatively, after the battery structure volume layer is a bi-cell structure, it is impregnated in an organic electrolyte, and the resulting object is put into a pouch and sealed to obtain A lithium ion polymer battery is used as the secondary battery of the present invention.

Furthermore, in addition to the steps described above, the method of manufacturing a secondary battery of the present invention may further include the method of manufacturing the SiOC structure, the method of manufacturing the negative electrode composition, and the method of manufacturing the negative electrode. step.

Examples and comparative examples are shown below to describe the present invention more specifically, but the present invention is not limited to these examples. [Example]

Various analyses and evaluations were performed on the materials manufactured in each Example and each Comparative Example. First, the various analysis and evaluation methods are shown below. In addition, in the following, Ph represents a phenyl group, and Me represents a methyl group.

<Scanning electron microscope (SEM) observation> SEM observation was performed on each material manufactured in the examples and comparative examples. As the SEM, an ultra-high-resolution analysis scanning electron microscope SU-70 (manufactured by Hitachi High-technologies Co., Ltd.) and a 3D Real Surface View Microscope (3D Real Surface View Microscope) VE-9800 (Keyence (Manufactured by Keyence Co., Ltd.), measured at the specified acceleration voltage.

(Determination of particle size distribution) The particle size distribution of each SiOC structure and SiOC material manufactured in the following Examples 1 to 4 and Comparative Example 1 were measured, and the 10%, 50%, and 90% cumulative mass particle diameter distribution diameters (D10, D50 and D90). The measurement method of particle size distribution is as follows. Take a small amount of the prepared hydrogen polysilsesquioxane sintered product containing silicon nanoparticles into a beaker, add a few drops of water and 0.5% Triton X-100 aqueous solution, using Nippon Seiki Co., Ltd. The US-150 ultrasonic homogenizer manufactured by the company was subjected to dispersion treatment for 3 minutes to prepare samples for measurement. The measurement sample was measured using a laser diffraction scattering particle diameter distribution measuring device MT3300II manufactured by MicrotracBEL Co., Ltd.

＜Elemental Analysis Method＞ For carbon element analysis, as a carbon element analysis device using the oxygen cycle combustion-thermal conductivity detector (Thermal Conductivity Detector, TCD) detection method, the NCH-21 model manufactured by Sumika Analysis Center Co., Ltd. is used. For oxygen element analysis, As an oxygen element analysis device using high-temperature carbon reaction-non-dispersive infrared (NDIR) detection method, Horiba Manufacturing Co., Ltd.'s EMGA-2800 is used, and Si element analysis is used as the use of ashing-alkali melting- An acid-dissolved-inductively coupled plasma (Inductively Coupled Plasma, ICP) luminescence analysis device for silicon element analysis was performed using SPS4000 manufactured by Seiko Instruments Inc. for elemental analysis.

＜Measurement of BET specific surface area＞ Regarding the BET specific surface area, after putting 1 g of sample powder into the measuring cell, set the degassing conditions to 250°C for 1 hour, and use the automatic specific surface area measuring device Macsorb (registered trademark) HM Model-1210 (Made by Mountech Corporation) for measurement.

＜Evaluation of battery characteristics＞ A negative electrode active material containing the materials produced in the Examples and Comparative Examples was prepared, and the negative electrode and lithium ion secondary battery using these negative electrode active materials were subjected to a charge-discharge cycle test as described below to evaluate battery characteristics. The following shows its Cheng Shun. Use HJR-110mSM, HJ1001SM8A or HJ1010mSM8A manufactured by Beidou Electric Works, charging and discharging are measured with constant current. At this time, with respect to the weight of the negative electrode active material (SiOC particles) per 1 g, a current value of 0.05 C, which is one-twentieth relative to the theoretical capacity, is used. In addition, it is assumed that the battery voltage drops to 0 V during charging and the battery voltage reaches 1.5 V during discharge. At the time of switching between charging and discharging, discharge is performed after 30 minutes of inactivity by opening the circuit.

Under the conditions, 50 cycles of charge and discharge were repeated to determine the battery characteristics. In addition, the reversible capacity is set as the initial discharge capacity, the initial charge-discharge rate is set as the ratio of the discharge capacity to the charge capacity in the first cycle, and the capacity retention rate after the cycle test is defined as the ratio after the cycle relative to the initial charge The charging capacity is expressed.

[Example 1] (MeSiO _0.5 ) (Production of silicon nanoparticle/methyl polysilsesquioxane composite) In a beaker, 100 g of 0.01 M acetic acid aqueous solution and 100 g of silicon nano powder (Sigma Orich ( Sigma Aldrich) company; the volume-based average particle diameter is less than 100 nm; but the particle diameter exceeds 10 nm) 10 g, using an ultrasonic cleaner to prepare silicon nanoparticle dispersion. Next, 100 g of a 0.01 M acetic acid aqueous solution was placed in a 300 ml three-necked flask, and 24.3 g (178 mmol) of methyltrimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise to the aqueous acetic acid solution at 25°C under stirring. ), let it react for 30 minutes. Then, the silicon nanoparticle dispersion was added to the resulting reaction solution, and then stirred at room temperature for 1 hour. To the mixed solution obtained in this way, 2.00 g (20 mmol) of hydrochloric acid with a concentration of 36% by weight was further added, and stirred at room temperature for 10 seconds, and the stirring was stopped. Then, the mixed solution was allowed to stand overnight, and the resulting reaction product was filtered with a membrane filter (pore size 0.45 μm, hydrophilic) to recover the solid. The obtained solid was dried under reduced pressure at 80° C. for 10 hours to obtain 21.9 g of silicon nanoparticle/methylpolysilsesquioxane composite (1) powder. A part of the powder of the silicon nanoparticle/methylpolysilsesquioxane composite (1) obtained in this way was tested by SEM observation. Furthermore, in this example, 0.01 M acetic acid aqueous solution was used in the hydrolysis reaction, so the calculated pH during the hydrolysis reaction was 3.29. In addition, 0.1 M hydrochloric acid was used in the polymerization reaction, so the pH during the polycondensation reaction was calculated to be 1.

(Manufacturing of SiOC structure) Next, 21.9 g of the powder of the silicon nanoparticle/methyl polysilsesquioxane composite (1) was placed in an SSA-S grade alumina boat, and the alumina boat The dish is placed in a vacuum purged tube furnace KTF43N1-VPS (manufactured by Koyo Thermo System). As the heat treatment conditions, under an argon atmosphere (high-purity argon 99.999%), argon is supplied at a flow rate of 250 ml/min, and the temperature is increased at a rate of 4°C/min, and heat treatment is performed at 1200°C for 5 hours. The sintered product of silicon nanoparticle/methyl polysilsesquioxane complex (1) is obtained. Then, the resulting sintered product was crushed and crushed for 5 minutes in a mortar, and classified using a stainless steel sieve with a pore size of 32 μm, thereby obtaining silicon nanoparticle/methyl polysilsesquioxane with a maximum particle diameter of 32 μm The sintered product of the composite (1) [SiOC structure (1)] powder is 18.9 g. A part of the SiOC structure (1) powder was tested in SEM observation, particle size distribution measurement, element analysis, and BET specific surface area measurement by the method described above.

(Manufacture of negative electrode composition and negative electrode body) Add 3.2 g of SiOC particles (3) and 0.4 g of acetylene black manufactured by Denka Co., Ltd. to 20 g of a 2% by weight aqueous solution of carboxymethyl cellulose, and mix for 15 minutes with a stir bar in the flask After that, distilled water was added so that the solid content concentration became 15% by weight, and further stirred for 15 minutes to prepare a slurry composition. The slurry-like composition was transferred to a thin-film rotary high-speed mixer (Filmix 40-40 type) manufactured by Primix, and the rotation speed was 20 m/s for 30 seconds Stir to disperse. For the slurry after the dispersion treatment, the slurry was applied to a copper foil roll with a thickness of 150 μm by a doctor blade method.

Air-dried for 30 minutes after coating, and then dried on a hot plate at 80°C for 90 minutes. After drying, the negative electrode sheet was pressed using a 2 t small precision roller press (manufactured by Thank-Metal). After pressing, press the electrode with a 14.50 mm electrode punch HSNG-EP, and use a glass tube oven GTO-200 (Shibata Scientific (SIBATA)) to dry under reduced pressure at 80°C for more than 12 hours to produce a negative electrode body.

(Manufacturing and Evaluation of Lithium Ion Secondary Battery) A 2032-type coin battery (lithium ion secondary battery) 300 having the structure shown in FIG. 6 was produced. Metal lithium was used as the positive electrode (lithium counter electrode) 303, a microporous polypropylene film was used as the separator 302, and the negative electrode body was used as the negative electrode (negative material) 301. The mixed solvent of LiPF ₆ ethylene carbonate and diethyl carbonate 1:1 (volume ratio) is used as the electrolyte. Then, evaluation of the battery characteristics of the lithium ion secondary battery was carried out. As the charging and discharging test machine, HJ1001SM8A manufactured by Beidou Electric Works was used. As the charging and discharging conditions, both charging and discharging are performed at a constant current at 0.05 C, the discharge end voltage is set to 1 mV, and the charge end voltage is set to 1500 mV.

[Example 2] (MePhSiO _0.5 ) In the production of the silicon nanoparticle/methylpolysilsesquioxane composite (1) of Example 1, 14.4 g (142 mmol) of methyltrimethoxysilane and Except for the mixture of 7.1 g (36 mmol) of phenyltrimethoxysilane instead of 24.3 g of methyltrimethoxysilane, the same procedure as in Example 1 was used to produce silicon nanoparticle/methylpolysilsane Siloxane complex (2) and its sintered [SiOC structure (2)] powder. In addition, as in Example 1, a part of the silicon nanoparticle/methylpolysilsesquioxane composite (2) was observed by SEM, and then a part of the SiOC structure (2) powder was used The method is used for SEM observation, particle size distribution measurement, element analysis and BET specific surface area measurement. Furthermore, the SiOC structure (2) obtained in this example was used instead of the SiOC structure (1) obtained in Example 1. Except for this, the negative electrode composition and the negative electrode body and lithium were produced in the same manner as in Example 1. Ion secondary batteries, and evaluation of battery characteristics.

[Example 3] (MeSiO _0.7 ) In the production of the silicon nanoparticle/methylpolysilsesquioxane composite (1) of Example 1, the dropping amount of methyltrimethoxysilane was changed to 42.5 g. Except for this, the silicon nanoparticle/methyl polysilsesquioxane composite (3) and its sintered product [SiOC structure (3)] powder were produced by the same procedure as in Example 1. . In addition, as in Example 1, a part of the silicon nanoparticle/methylpolysilsesquioxane composite (3) was observed by SEM, and then a part of the SiOC structure (3) powder was used The method was tested in SEM observation, particle size distribution measurement and BET specific surface area measurement. Furthermore, the SiOC structure (3) obtained in this example was used instead of the SiOC structure (1) obtained in Example 1. Except for this, the negative electrode composition, the negative electrode body, and lithium were produced in the same manner as in Example 1. Ion secondary batteries, and evaluation of battery characteristics.

[Example 4] (MePhSiO _0.7 ) In the production of the silicon nanoparticle/methylpolysilsesquioxane composite (1) of Example 1, 34.0 g of methyltrimethoxysilane and phenyltrimethoxysilane were used Except for the mixture of 12.4 g of silyl silane instead of 24.3 g of methyl trimethoxy silane, the same procedure as in Example 1 was used to produce a silicon nanoparticle/methyl polysilsesquioxane composite (4) Its sintered [SiOC structure (4)] powder. In addition, as in Example 1, a part of the silicon nanoparticle/methylpolysilsesquioxane composite (4) was tested for SEM observation, and a part of the SiOC structure (4) powder was used The method was tested in SEM observation, particle size distribution measurement and BET specific surface area measurement. Furthermore, the SiOC structure (4) obtained in this example was used instead of the SiOC structure (1) obtained in Example 1. Except for this, the negative electrode composition and the negative electrode body and lithium were produced in the same manner as in Example 1. Ion secondary batteries, and evaluation of battery characteristics.

[Comparative Example 1] (MeSiO _0.5 ) Place 3.6 g of water, 7 g of isopropanol, and silicon nanometer powder (Sigma Aldrich) in a beaker, less than 100 nm (volume-based average particle diameter, but more than 10 nm)) 4.12 g, using an ultrasonic cleaner to prepare silicon nanoparticle dispersion. After adding 10.0 g of methyltrimethoxysilane to the dispersion, 0.1 g of 1 M hydrochloric acid was added and stirred for 30 minutes. The reaction solution was placed in a thermostat at 80° C. and left overnight to prepare a silicon nanoparticle/methylpolysilsesquioxane composite (5) in the form of a massive gel.

After placing the obtained silicon nanoparticle/methyl polysilsesquioxane composite (5) in a boat made of SSA-S grade alumina, the boat was placed in a vacuum purged tube furnace KTF43N1 -In VPS (manufactured by Koyo Thermo System), as the heat treatment condition, argon is supplied at a flow rate of 250 ml/min under an argon atmosphere (high purity argon 99.999%), and at the same time at 4°C/ The temperature is increased within minutes, and the mixture is sintered at 1200°C for 5 hours to prepare a sintered product of silicon nanoparticle/methyl polysilsesquioxane complex (5).

Then, the sintered product of the silicon nanoparticle/methylpolysilsesquioxane composite (5) obtained as described above was pulverized in a mortar and classified using a stainless steel sieve with a pore size of 32 μm to obtain 7.2 g powder of SiOC composite material (5) with a maximum particle diameter of 32 μm.

As for a part of the SiOC composite material obtained in this way, SEM observation, particle size distribution measurement, and BET specific surface area measurement were performed in the same manner as in Example 1. Furthermore, except that the SiOC composite material obtained in this comparative example was used instead of the SiOC structure obtained in Example 1, a negative electrode composition, a negative electrode body, and a lithium ion secondary battery were produced in the same manner as in Example 1, and Perform evaluation of battery characteristics.

[Comparative Example 2] (MeSiO _0.5 ) First, by the same procedure as in Example 1, a silica nanoparticle dispersion was prepared, and methyltrimethoxysilane was hydrolyzed with a 0.01 M acetic acid aqueous solution, and the resulting hydrolysis reaction solution Add the silicon nanoparticle dispersion liquid to it, and stir at room temperature for 1 hour. Then, 2.00 g (20 mmol) of 36% by weight hydrochloric acid was added to the mixed solution obtained in this way, and the polymerization reaction of the hydrolyzate of the silane compound was carried out while stirring the mixed solution at room temperature overnight. As a result, Finally, a cake-like silicon nanoparticle/methyl polysilsesquioxane composite (6) is obtained. This composite (6) is produced in a state of being attached to the inside of the reaction vessel, and therefore is difficult to recover. Therefore, a part of the composite (6) was collected for SEM observation, and the remaining part was discarded without being burnt.

＜Results＞ (SEM observation) Figure 1 shows each of the silicon nanoparticle/methylpolysilsesquioxane composites (1) ~ the silicon nanoparticle/methylpolysilsesquioxane composite manufactured in Example 1 to Example 4, respectively SEM photo of body (4). In addition, FIG. 2(a) and FIG. 2(b) respectively show each SiOC structure (1) to SiOC structure (4) manufactured in Example 1 to Example 4, and the SiOC manufactured in Comparative Example 1 SEM photo (10,000 times) of composite material (5). In addition, FIG. 2(c) shows an SEM photograph (20,000 times) of the silicon nanoparticle/methylpolysilsesquioxane composite (6) produced in Comparative Example 2. Furthermore, regarding each SiOC structure manufactured in Example 1, the SEM photograph (50,000 times) obtained by increasing the magnification is shown in FIG. 3.

In the SEM photographs shown in Fig. 2(a) and Fig. 3(a) and Fig. 3(b), the SiOC structure (1) to the SiOC structure (4) produced in Example 1 to Example 4 are all confirmed The silicon nano-particles are uniformly coated by the SiOC coating derived from polysilsesquioxane, and a plurality of silicon nano-particles are connected through the SiOC coating. In addition, it can be seen from the SEM photograph shown in Fig. 1 that the silicon nanoparticle/methylpolysilsesquioxane composite (1)~silicon nanoparticle/methylpolysiloxane synthesized in Example 1 to Example 4 The semi-siloxane complex (4) is made of polysilsesquioxane-coated silicon nanoparticles produced by the hydrolysis and polycondensation reaction of a prescribed silane compound. Multiple silicon nanoparticles pass through the polysilsesquioxane The alkane coating is connected. That is, regarding the SiOC coating of the SiOC structure (1) to the SiOC structure (4) obtained by the heat treatment, it is considered that although the polysilsesquioxane coating is ceramicized by the heat treatment, it is considered to be converted to SiOC The coating does not undergo major morphological changes due to heat treatment, and can maintain the coating structure of the silicon nanoparticle obtained by the coating. In addition, focusing on the synthesis process of silicon nanoparticle/polysilsesquioxane composite, in Examples 1 to 4, in the presence of an acidic catalyst, a predetermined silane compound was hydrolyzed under stirring, and then During the polycondensation, the polycondensation reaction is promoted by leaving the reaction solution overnight without stirring. It is speculated that the following silicon nanoparticle/polysilsesquioxane complex is formed, which has silicon nanoparticle The structure in which the polysilsesquioxane produced by the polycondensation is relatively uniformly covered.

On the other hand, compared with Example 1 to Example 4, regarding the SiOC composite material produced in Comparative Example 1, as can be seen from the SEM photograph of Figure 2(b), no polysilsesquioxane derived from The SiOC part is covered with silicon nanoparticle, and a large number of silicon nanoparticle is confirmed to be exposed to the outside. That is, regarding the SiOC composite material produced in Comparative Example 1, it was confirmed that the silicon nanoparticle was not uniformly covered by the SiOC part, but a structure in which the two were aggregated in disorder. The reason for the appearance of such agglomerated structure is that in Comparative Example 1, methyltrimethoxysilane and hydrochloric acid were added to the silicon nanoparticle dispersion at one time to promote the hydrolysis and polycondensation of methyltrimethoxysilane. Synthesize a silicon nanoparticle/methyl polysilsesquioxane complex in the form of a massive gel.

Furthermore, in Comparative Example 2 in which the reaction solution was continuously stirred during the polycondensation after hydrolysis, a silicanoparticle/methylpolysilsesquioxane complex in the form of a cake was formed (see the SEM picture of Figure 2(c)) ).

As described above, in the embodiment of the present invention, the following SiOC structure can be manufactured, which has silicon nanoparticle is uniformly coated by SiOC coating derived from polysilsesquioxane, and a plurality of silicon nanoparticle is passed through SiOC The structure of the coating connection. Here, the SiOC coating layer has no surface roughness, etc., and has a smooth surface.

Next, regarding each SiOC structure manufactured in Examples 1 to 4 and the SiOC composite material manufactured in Comparative Example 1, the graph of the particle size distribution obtained by the particle size distribution measurement is shown in Fig. 4(a), Figure 4(b). Furthermore, the results of the volume-based average particle diameter (μm), BET specific surface area (m ² /g), and elemental analysis (mass %) measured for these SiOC structures and SiOC composite materials are shown in Table 1.

[Table 1] species Volume basis average particle diameter (frequency%) (μm) Volume basis cumulative% particle diameter (μm) D90/D10 ratio BET specific surface area (m ² /g) Elemental analysis (mass%) D10 D50 D90 Si O C Example 1 MeSiO _0.5 6.24 2.19 4.70 10.88 5 5.2 75.4 19.5 4.85 Example 2 MePhSiO _0.5 6.46 1.79 4.49 11.85 6.6 4.9 68.6 17.8 12.5 Example 3 MeSiO _0.7 11.4 5.35 10.07 17.26 3.2 2.5 - - - Example 4 MePhSiO _0.7 17.71 7.37 15.45 27.59 3.7 1.3 - - - Comparative example 1 MeSiO _0.5 17.49 2.15 14.75 33.55 15.6 23.2 - - - -: Not determined

First, as for Comparative Example 1, as shown in Table 1 and Figure 4(a) and Figure 4(b), it was confirmed that although the average particle diameter was large, the BET specific surface area showed a value of 23.2 m ² /g. The SiOC structure of the example is significantly larger than that. Regarding the reason for this result, it is believed that the reason is that, as observed from the SEM photograph (Figure 2(b)), the composite material is to be thinned by the crushing treatment, resulting in the generation of fine powder and the surface Rough. In this regard, compared with the particle size distribution graphs shown in Figs. 4(a) and 4(b), in the particle size distribution of Comparative Example 1, the peak shifts in the direction of the larger particle diameter and is on the left side of the peak. (That is, the area where the particle diameter is small) The distribution is also observed at a predetermined level, and the result of observing a wide distribution is consistent.

In contrast, it can be seen that all the SiOC structures produced in Examples 1 to 4 show a BET specific surface area of less than 10 m ² /g, which is a low value. In addition, it can be understood from the particle size distribution graphs of Figures 4(a) and 4(b) that the particle size distribution peaks of the SiOC structures of Examples 1 to 4 are sharp and are provided in a more uniform particle size form . In this regard, as shown in the SEM photograph of Fig. 2(a), the silicon nanoparticle is uniformly covered by the polysilsesquioxane produced by polycondensation to form a uniform structure without surface roughness. After sintering, the uniform structure without surface roughness is maintained.

Furthermore, compared with the SiOC structure manufactured in Examples 1 to 3, the average particle diameter of the SiOC structure manufactured in Example 4 was larger and showed a value larger than that of Comparative Example 1 (17.71 μm). ). However, Example 4 is different from Comparative Example 1, in that the BET specific surface area is a significantly small value of 1.3 m ² /g (Table 1), and it can be seen that the peak of the particle size distribution is also sharp (Figure 4(b)). That is, it can be seen that Example 4 has a large particle diameter, but as a whole, it has a uniform structure without surface roughness similarly to Examples 1 to 3. This aspect is also clear from the SEM photograph shown in Fig. 2(a).

(Result of charge and discharge cycle test) The results of the charge-discharge cycle test performed on the lithium ion batteries prepared in each of Examples 1 to 4 and Comparative Example 1 are shown in Table 2 and Figs. 5(a) and 5(b). In addition, in FIGS. 5(a) and 5(b), the solid line represents the charge capacity, and the broken line represents the discharge capacity.

[Table 2] Composition ratio Initial charging capacity (mAh/g) Initial discharge capacity (mAh/g) FCE 5 cycles-50 cycles capacity maintenance rate 5 cycles-50 cycles average CE Example 1 MeSiO _0.5 2671 2284 85.5% 88.8% 99.0% Example 2 MePhSiO _0.5 2581 2225 86.2% 76.3% 98.8% Example 3 MeSiO _0.7 2723 2218 81.5% 86.7% 99.2% Example 4 MePhSiO _0.7 2229 1830 82.1% 65.6% 98.8% Comparative example 1 MeSiO _0.5 2657 2252 84.8% 32.9% 97.2%

First, as can be understood from Fig. 5(a) and Fig. 5(b), the capacity decline tends to be relatively stable starting from around 5 cycles. Therefore, regarding the result of the charge-discharge cycle test, the first The capacity retention rate and the average coulombic efficiency (average CE) of 50 cycles relative to the fifth cycle were used to evaluate the performance of each lithium ion battery.

As a result, as shown in Table 2 and Figs. 5(a) and 5(b), the lithium ion batteries produced in Examples 1 to 4 were tested in the charge-discharge cycle test from 5 cycles to 50 The cycle capacity retention rate all showed a value of 65% or more, showing an extremely good capacity retention rate. In addition, the average coulombic efficiencies of these lithium ion batteries from 5 cycles to 50 cycles all show values around 99%, and they maintain extremely good average coulombic efficiencies.

In contrast, regarding the lithium ion battery produced in Comparative Example 1, compared with Examples 1 to 4 in which the SiOC structure specified in the present invention was used as the negative electrode material, the capacity retention rate of 5 to 50 cycles It only shows a value of 32.9%, which is extremely poor. Furthermore, the coulombic efficiency of the lithium ion battery of Comparative Example 1 from 5 cycles to 50 cycles also showed a value of only 97.2%, which is inferior to the lithium ion batteries of Examples 1 to 4.

As described above, the results of Examples 1 to 4 and Comparative Example 1 show that when the SiOC structure specified in the present invention is used, a secondary battery with high capacity retention rate and coulomb efficiency can be provided. [Industrial availability]

The present invention has high industrial applicability in materials/chemical fields such as SiOC materials, negative electrode active materials, negative electrode materials, and electrical and electronic fields such as secondary batteries and various electronic devices.

300: Lithium ion secondary battery (coin battery) 301: negative electrode material (negative electrode) 302: Partition 303: Lithium counter electrode (positive electrode)

FIG. 1 is a diagram showing a scanning electron microscope (SEM) photograph (1,000 times) of the silicon nanoparticle/methylpolysilsesquioxane composite synthesized in each of Examples 1 to 4. FIG. 2(a) is a diagram showing an SEM photograph (10,000 times) of the SiOC structure obtained in each of Example 1 to Example 4. FIG. FIG. 2(b) is a diagram showing an SEM photograph (10,000 times) of the SiOC material obtained in Comparative Example 1. FIG. FIG. 2(c) is a diagram showing a SEM photograph (20,000 times) of the silicon nanoparticle/methylpolysilsesquioxane composite obtained in Comparative Example 2. FIG. 3(a) and 3(b) are diagrams showing SEM photographs of the SiOC structure obtained in Example 1. FIG. Figure 3(a) is based on a magnification of 10,000 times, and Figure 3(b) is based on a magnification of 50,000 times. 4(a) and 4(b) are graphs showing the results of measuring the particle size distribution of the SiOC structure obtained in Examples 1 to 4 and the SiOC material obtained in Comparative Example 1. FIG. Figures 5(a) and 5(b) show the measurement of battery capacity (a) and coulombic efficiency of lithium ion secondary batteries produced in Examples 1 to 4 and Comparative Example 1 through a charge-discharge cycle test (B) A graph of the result obtained. Fig. 6 is a diagram showing a configuration example of a coin-type lithium ion battery.

Claims (29)

A silicon oxycarbide structure, comprising: (A) at least one silicon-based fine particle; and (B) a silicon oxycarbide coating containing at least Si (silicon), O (oxygen) and C (carbon ) As a constituent element, the at least one silicon-based fine particle is covered by the silicon oxycarbide coating, the Buert specific surface area of the silicon oxycarbide structure is 20 m ² /g or less, and is diffracted by laser The cumulative 10% particle size (D10), cumulative 50% particle size (D50) and cumulative 90% particle size (D90) obtained by the scattering particle size distribution measurement method satisfy 1 nm≦D50≦990 μm and D90/D10≦13.0 condition. The silicon oxycarbide structure according to item 1 of the scope of patent application, wherein the at least one silicon-based fine particle and the silicon oxycarbide coating are chemically bonded to each other. The silicon oxycarbide structure described in the first item of the scope of patent application, wherein the Buert specific surface area is 15 m ² /g or less. The silicon oxycarbide structure according to the first item of the scope of patent application, wherein the Buert specific surface area is 10 m ² /g or less. The silicon oxycarbide structure according to any one of items 1 to 4 of the scope of patent application, wherein the cumulative 50% particle size (D50) satisfies the condition of 500 nm≦D50≦100 μm. In the silicon oxycarbide structure described in item 1 of the scope of patent application, the cumulative 50% particle size (D50) satisfies the condition of 1 μm≦D50≦20 μm. The silicon oxycarbide structure described in the first item of the scope of patent application, wherein the cumulative 10% particle size (D10) and the cumulative 90% particle size (D90) satisfy the condition of 2.0≦D90/D10≦12.0. The silicon oxycarbide structure described in the first item of the scope of patent application, wherein the cumulative 10% particle size (D10) and the cumulative 90% particle size (D90) satisfy the condition of 2.5≦D90/D10≦8.0. The silicon oxycarbide structure according to the first item of the scope of patent application, wherein the at least one silicon-based fine particle has a volume-based average particle diameter in the range of 1 nm to 2 μm. The silicon oxycarbide structure according to claim 1, wherein the at least one silicon-based fine particle has a volume-based average particle diameter in the range of 10 nm to 500 nm. The silicon oxycarbide structure according to claim 1, wherein the at least one silicon-based fine particle is completely covered by the silicon oxycarbide coating to form a plurality of secondary particles, the plurality of secondary particles The particles are connected to each other via the silicon oxycarbide coating. The silicon oxycarbide structure described in item 1 of the scope of the patent application, wherein based on the total mass of the silicon oxycarbide structure, it contains silicon in the range of 50% to 90% by mass, and 5% to 35% by mass Oxygen in a range and carbon in a range of 2% by mass to 35% by mass are main constituent elements. A composition for a negative electrode, which contains the silicon oxycarbide structure as described in item 1 of the scope of the patent application as a negative electrode active material. The composition for a negative electrode as described in item 13 of the scope of the patent application further contains a carbon-based conductive assistant and/or a binder. A negative electrode containing the negative electrode composition as described in item 13 of the scope of the patent application. A secondary battery includes at least one negative electrode as described in item 15 of the scope of the patent application. The secondary battery described in item 16 of the scope of patent application is a lithium ion secondary battery. A method for manufacturing a silicon oxycarbide structure, comprising: step (p), hydrolyzing the silane compound represented by the general formula (I), and then performing condensation polymerization in the presence of silicon-based fine particles, thereby generating a compound containing at least one The silicon polymer coating is a silicon-based microparticle/silicon-containing polymer composite formed by coating at least one silicon-based microparticle; and step (q), in a non-oxidizing gas atmosphere, the silicon-based microparticle/silicon-containing polymer composite The composite body is subjected to heating treatment, thereby converting it into the silicon oxycarbide structure as described in any one of items 1 to 10 of the scope of the patent application: R ¹ _n SiX ¹ _4-n … (I) (wherein , R ¹ is hydrogen, a hydroxyl group or a substituted or unsubstituted hydrocarbon with a carbon number of 1 to 45, and in a hydrocarbon with a carbon number of 1 to 45, any hydrogen may be substituted by halogen, and any -CH ₂ -may be -O-, -CH=CH-, cycloalkylene or cycloalkenylene substitution, X ¹ is halogen, alkyloxy or acetoxy with 1 to 6 carbon atoms, present in R ¹ and X ¹ respectively In the case of multiple, they are independent of each other, and n is an integer of 0 to 3). The method for manufacturing a silicon oxycarbide structure as described in item 18 of the scope of patent application, wherein the silane compound represented by the general formula (I) is a silane compound represented by the following general formula (II): R ¹⁰ Si(R ⁷ )(R ⁸ )(R ⁹ ) …(II) (wherein R ⁷ , R ⁸ and R ⁹ are each independently hydrogen, halogen, hydroxy, or alkyl oxygen having 1 to 4 carbon atoms Group, R ^{10 is} selected from the group consisting of substituted or unsubstituted alkyl groups having 1 to 45 carbon atoms, substituted or unsubstituted aryl groups, and substituted or unsubstituted arylalkyl groups , And in an alkyl group with 1 to 45 carbon atoms, any hydrogen can be substituted by halogen, and any -CH ₂ -can be substituted by -O-, -CH=CH-, cycloalkylene or cycloalkenylene, In the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen can be substituted by halogen, and any -CH ₂ -can be -O-, -CH=CH-, cycloalkylene or Cycloalkenyl substitution). The method for manufacturing a silicon oxycarbide structure as described in the scope of patent application, wherein the silicon-containing polymer comprises at least one selected from the group consisting of polysilsesquioxanes, and the polysilsesquioxanes Siloxanes have polysilsesquioxane structures represented by the following general formula (III), general formula (IV), general formula (V) and general formula (VI) respectively:

(In the formula, R ¹ and R ⁴ are each independently selected from a substituted or unsubstituted alkyl group having 1 to 45 carbon atoms, a substituted or unsubstituted aryl group, and a substituted or unsubstituted aryl group In the group of alkyl groups, in the alkyl group with 1 to 45 carbon atoms, any hydrogen can be substituted by halogen, and any -CH ₂ -can be -O-, -CH=CH-, cycloalkylene Or cycloalkenylene substitution. In the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen can be replaced by halogen, and any -CH ₂ -can be -O-, -CH=CH -Or cycloalkylene substitution; R ² , R ³ , R ⁵ and R ⁶ are each independently selected from hydrogen, substituted or unsubstituted alkyl having 1 to 45 carbons, and substituted or unsubstituted aryl In the group consisting of substituted or unsubstituted arylalkyl groups, in the alkyl group with 1 to 45 carbon atoms, any hydrogen may be substituted by halogen, and any -CH ₂ -may be -O -, -CH=CH-, cycloalkylene, cycloalkenylene or -SiR ¹ ₂ -substituted, in the alkylene group in the substituted or unsubstituted arylalkyl group, any hydrogen may be halogenated Substitution, any -CH ₂ -may be substituted by -O-, -CH=CH-, cycloalkylene, cycloalkenylene or -SiR ¹ ₂ -; n represents an integer of 1 or more). The method for manufacturing a silicon oxycarbide structure as described in item 18 of the scope of patent application, wherein the following steps (p-1) to the following steps (p-3) are performed in the step (p): Step (p-1), adding the silane compound represented by the general formula (I) to an acidic solution with a pH of 3-6 to hydrolyze the silane compound; Step (p-2), adding silicon-based fine particles or a dispersion liquid thereof to the reaction solution obtained by the step (p-1); In step (p-3), a predetermined amount of acid or its solution is added to the mixed solution obtained in the step (p-2), and the pH of the mixed solution is adjusted to 2 or less, and the The mixed solution is allowed to stand still at a predetermined temperature for a predetermined period of time, whereby the polycondensation of the silane compound proceeds to produce the silicon-based fine particles/silicon-containing polymer composite. The method for manufacturing a silicon oxycarbide structure as described in item 18 of the scope of patent application, wherein the following steps (p-1') to the following steps (p-3') are carried out in the step (p): In step (p-1'), in an acidic solution with a pH of 3-6, the silane compound represented by the general formula (I) is gradually added under stirring conditions, and the Silane compounds are hydrolyzed at a prescribed time and at a prescribed temperature; Step (p-2'), adding silicon-based fine particles or their dispersion to the reaction solution obtained by the above-mentioned step (p-1'), so that the silicon-based fine particles or their dispersion are uniformly dispersed in all The reaction solution; In step (p-3'), a predetermined amount of acid or its solution is added to the mixed solution obtained in the step (p-2'), and the pH of the mixed solution is adjusted to 2 or less, and then, The mixed solution is allowed to stand for a predetermined time and at a predetermined temperature, whereby the polycondensation of the silane compound proceeds to produce the silicon-based fine particles/silicon-containing polymer composite. The method for manufacturing a silicon oxycarbide structure as described in item 18 of the scope of patent application, wherein in the step (p), an acid or its aqueous solution is used as an acid catalyst. The method for manufacturing a silicon oxycarbide structure as described in item 18 of the scope of the patent application, wherein in the general formula (I), n=1, R ¹ is a hydrocarbon with 1 to 10 carbons, and there are three Xs ^{1 is} each independently halogen, alkyloxy having 1 to 6 carbons, or acetoxy. The method for manufacturing a silicon oxycarbide structure as described in claim 18, wherein in the step (p), the silane compound represented by the general formula (I) comprises a compound selected from methyl trimethyl At least one silane compound in the group consisting of oxysilane and phenyltrimethoxysilane. The method for manufacturing a silicon oxycarbide structure according to the 18th patent application, wherein the non-oxidizing gas atmosphere in the step (q) is an atmosphere containing an inert gas. The method for manufacturing a silicon oxycarbide structure according to the 18th patent application, wherein the non-oxidizing gas atmosphere in the step (q) is an atmosphere containing nitrogen and/or argon. The method for manufacturing a silicon oxycarbide structure as described in item 18 of the scope of patent application, wherein in the step (q), the silicon-based fine particles/silicon-containing polymer composite is heated to 400°C to 1800°C The temperature within the range of 30 minutes to 10 hours is heated at the temperature. A method of manufacturing a composition for a negative electrode includes: obtaining the composition for a negative electrode by using the silicon oxycarbide structure as described in the first item of the patent application as a negative electrode active material.

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