KR102680032B1 - Solid electrolyte for lithium secondary battery, method for preparing the same and lithium secondary battery including the solid electrolyte - Google Patents

Abstract

By applying a silica gel-based solid composite electrolyte with excellent mechanical strength to a lithium secondary battery, a solid electrolyte for a lithium secondary battery that can improve the stability of the battery, such as preventing liquid leakage and shape deformation within the battery, a method of manufacturing the same, and A lithium secondary battery including the solid electrolyte is disclosed. The solid electrolyte for a lithium secondary battery includes an aminosilane-based salt compound; silicate-based compounds; and a lithium salt-containing liquid electrolyte.

Description

Solid electrolyte for lithium secondary battery, manufacturing method thereof, and lithium secondary battery including the solid electrolyte {Solid electrolyte for lithium secondary battery, method for preparing the same and lithium secondary battery including the solid electrolyte}

The present invention relates to a silica gel-based solid electrolyte for lithium secondary batteries applicable to lithium secondary batteries, a manufacturing method thereof, and a lithium secondary battery containing the solid electrolyte. More specifically, it relates to a silica gel-based solid composite electrolyte with excellent mechanical strength. The present invention relates to a solid electrolyte for a lithium secondary battery that can improve the stability of the battery by preventing liquid leakage and shape deformation within the battery by applying it to a lithium secondary battery, a method of manufacturing the same, and a lithium secondary battery containing the solid electrolyte. .

As interest in energy storage technology grows, its application areas expand to include energy from mobile phones, tablets, laptops and camcorders, and even electric vehicles (EVs) and hybrid electric vehicles (HEVs). Research and development on chemical devices is gradually increasing. Electrochemical devices are the field that is receiving the most attention in this regard, and among them, the development of lithium-based secondary batteries such as lithium-sulfur batteries that can be charged and discharged has become the focus of attention. Recently, capacity has been considered in the development of these batteries. To improve density and specific energy, research and development is being conducted on new electrode and battery designs.

Such lithium secondary batteries are largely composed of a positive electrode, a negative electrode, a separator, and an electrolyte, and among these, the liquid electrolyte accounts for a large portion as the electrolyte for lithium secondary batteries. Although the liquid electrolyte has the advantage of providing high ionic conductivity, it also has the problem of reducing the stability of the battery due to high vapor pressure, possibility of liquid leaking to the outside of the battery, and low ignition point.

In order to improve the stability of lithium secondary batteries, which have been pointed out as a disadvantage, the industry is applying liquid electrolytes using various materials or complexes of porous silica gel inorganic materials and liquid electrolytes, but they have not yet shown a clear effect. There is a situation. In particular, in the case of a composite using a porous silica gel inorganic material and a liquid electrolyte, the occurrence of leakage of the supported liquid electrolyte and the ease of the battery assembly process vary depending on the mechanical properties of the silica gel inorganic material that serves as the matrix. There is a need for methods to improve the mechanical properties of silica gel inorganic materials.

Therefore, the purpose of the present invention is to develop a lithium secondary battery that can improve the stability of the battery, such as preventing liquid leakage and shape deformation within the battery, by applying a silica gel-based solid composite electrolyte with excellent mechanical strength to the lithium secondary battery. To provide a solid electrolyte for a battery, a manufacturing method thereof, and a lithium secondary battery containing the solid electrolyte.

In order to achieve the above object, the present invention includes an aminosilane-based salt compound; silicate-based compounds; and a lithium salt-containing liquid electrolyte. It provides a gel-like solid electrolyte for a lithium secondary battery including a lithium salt-containing liquid electrolyte.

In addition, the present invention includes the steps of (a) mixing an aminosilane-based salt compound, a silicate-based compound, an organic acid, and a lithium salt-containing liquid electrolyte; (b) gelling the mixed solution by leaving it alone; (c) heat treating the gel to remove organic acids and by-products; and (d) drying the heat-treated gel to remove residual moisture.

In addition, the present invention, an anode; cathode; A solid electrolyte for a lithium secondary battery interposed between the positive electrode and the negative electrode; It provides a lithium secondary battery including a separator.

The solid electrolyte for a lithium secondary battery, the manufacturing method thereof, and the lithium secondary battery including the solid electrolyte according to the present invention are achieved by applying a silica gel-based solid composite electrolyte with excellent mechanical strength to the lithium secondary battery, thereby causing the leakage phenomenon and shape in the battery. It has the advantage of improving the stability of the battery, such as preventing deformation.

Figure 1 is an image showing the shape of a solid electrolyte before being subjected to pressure.

Hereinafter, the present invention will be described in detail.

The solid electrolyte for a lithium secondary battery according to the present invention is in a gel state and includes an aminosilane-based salt compound, a silicate-based compound, and a lithium salt-containing liquid electrolyte.

The gel-type (or gel-type) solid electrolyte for lithium secondary batteries according to the present invention is a silica gel-based solid composite electrolyte with excellent mechanical strength, and by applying it to lithium secondary batteries, leakage and shape deformation within the battery are prevented. It can be said to be a unique invention that can improve the stability of the battery by preventing

The aminosilane salt compound is an organosilicon that improves the stability of the battery by improving the mechanical strength of the electrolyte and preventing leakage and shape deformation within the battery. The aminosilane salt compound contains both cations and anions, and compounds that provide the cations include trimethyl[3-(triethoxysilyl)propyl]ammonium, 3-methyl-1-(3-triethoxysilyl)propyl)-imidazolium (3-methyl-1-(3-(triethoxysilyl)propyl)-imidazolium), 3-ethyl-1-(3-triethyl Toxysilyl)propyl)-imidazolium (3-ethyl-1-(3-(triethoxysilyl)propyl)-imidazolium) and N-(3-triethoxysilyl)propyl-pyridinium (N-[3-(triethoxysilyl) )propyl]-pyridinium), etc. can be exemplified. In addition, compounds that provide the anion include halogen anions (ex: Br-, Cl-, I-), bis(trifluoromethylsulfonyl)imide (TFSI-), and bis(fluoromethylsulfonyl)imide (TFSI-). Examples include rosulfonyl)imide (bis(fluorosulfonyl)imide; FSI-).

That is, the aminosilane salt compound is a mixture of at least one cation-donating compound and at least one anion-donating compound, and is trimethyl[3-(triethoxysilyl)propyl]ammonium chloride (Trimethyl[3) represented by the following formula 1: -(triethoxysilyl)propyl]ammonium chloride; 3-ethyl-1-(3-triethoxysilyl)propyl)-imidazolium bis(trifluoromethylsulfonyl)imide (3-ethyl-1- (3-(triethoxysilyl)propyl)-imidazolium bis(trifluoromethylsulfonyl)imide), 3-methyl-1-(3-triethoxysilyl)propyl)-imidazolium bis(fluorosulfonyl)imide (3-methyl Examples include -1-(3-(triethoxysilyl)propyl)-imidazolium bis(fluorosulfonyl)imide) and mixtures of two or more of these.

[Formula 1]

The content of the aminosilane salt compound is 0.01 to 6% by weight, preferably 0.05 to 4% by weight, and more preferably 2.7 to 3.3% by weight, based on the total weight of the solid electrolyte for a lithium secondary battery of the present invention. If the content of the aminosilane-based salt compound is less than 0.01% by weight based on the total weight of the solid electrolyte for a lithium secondary battery, the mechanical strength of the electrolyte obtained by using the aminosilane-based salt compound may decrease, and the aminosilane-based salt If the content of the compound exceeds 6% by weight, there may be no further effect of improving mechanical strength.

Next, the silicate-based compound is an additional ingredient that can be applied to shorten the gelation time of the electrolyte. The silicate-based compound includes tetraethyl orthosilicate (TEOS) and tetramethyl orthosilicate. Examples include tetramethyl orthosilicate (TMOS), tetra(iso-propyl) orthosilicate, and mixtures of two or more of these.

The content of the silicate-based compound (or the content of the material (ex: SiO ₂ , etc.) produced by the reaction of the silicate-based compound) is preferably 4 to 10% by weight based on the total weight of the solid electrolyte for a lithium secondary battery of the present invention. It may be 5 to 9% by weight, more preferably 8 to 9% by weight. If the content of the silicate-based compound is less than 5% by weight based on the total weight of the solid electrolyte for a lithium secondary battery, there is a risk that gelation will not occur, and if the content of the silicate-based compound exceeds 10% by weight, the mechanical strength may decrease. Deterioration problems may occur.

Next, the lithium salt-containing liquid electrolyte contains a liquefying agent and a lithium salt used to maximize the capacity of the battery, and can be used without particular restrictions as long as it contains lithium metal. Such lithium salts include lithium bis(trifluoromethane sulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium perchlorate (Lithium bis(fluorosulfonyl)imide). LiClO ₄ ; Lithium perchlorate, LiAsF ₆ ; Lithium hexafluoroarsenate, LiBF ₄ ; Lithium tetrafluoroborate, LiPF ₆ ; Lithium hexafluorophosphate. Roantimonate (LiSbF ₆ ), lithium difluoromethanesulfonate (LiC ₄ F ₉ SO ₃ ), lithium aluminate (LiAlO ₂ ), lithium tetrachloroaluminate (LiAlCl ₄ ), lithium chloride (LiCl), iodide Lithium (LiI), lithium bisoxalatoborate (LiB(C ₂ O ₄ ) ₂ ), lithium trifluoromethanesulfonylimide (LiN(C _x F _2x+1 SO ₂ )(C _y F _2y+1 SO ₂ ), (where x and y are natural numbers)), derivatives thereof, and mixtures thereof may be exemplified.

Meanwhile, the liquefying agent (deep eutectic solvent) is a substance that is solid at room temperature alone, but can change into a liquid state when mixed with lithium salt, and includes N-methylacetamide (NMAC), urea, and acetamide. , 1-methyl urea, 1,3-dimethyl urea, 1,1-dimethyl urea, thiourea, mixtures containing two or more of these, and substances having properties similar to these.

The content of the lithium salt-containing liquid electrolyte may vary depending on the type of lithium salt or other components, so it is not easy to specify, but for example, it is 50 to 95% by weight based on the total weight of the solid electrolyte for a lithium secondary battery of the present invention. , preferably 80 to 95% by weight, more preferably 85 to 90% by weight. If the content of the lithium salt-containing liquid electrolyte is outside the above range, problems may occur in which ion conduction is not smooth or the lithium salt does not dissociate in the solvent.

The solid electrolyte for a silica gel-based lithium secondary battery of the present invention containing the above components uses only tetraethyl orthosilicate (TEOS, a silicate-based compound) as a material for the silica matrix when synthesizing the existing silica gel-based electrolyte. In contrast, aminosilane-based salt compounds such as trimethyl[3-(triethoxysilyl)propyl]ammonium chloride (TPAC) were applied as materials for the silica matrix, thereby achieving superior mechanical strength compared to existing silica gel-based electrolytes. Therefore, it has the advantage that leakage does not occur even under pressure conditions and its shape can be maintained relatively intact.

Meanwhile, the silica matrix refers to a porous silica structure with a continuous passage from one side to the other side, and this structure allows ion transport in both directions when the liquid electrolyte is sufficiently contained in the pores. do. Additionally, because the silica matrix exists in a state containing a liquid electrolyte, its apparent properties are the same as those of a solid.

Next, a method for manufacturing a solid electrolyte for a lithium secondary battery according to the present invention will be described. The method for producing a solid electrolyte for a lithium secondary battery includes the steps of (a) mixing an aminosilane-based salt compound, a silicate-based compound, an organic acid, and a lithium salt-containing liquid electrolyte, (b) leaving the mixed solution to gel, (c) ) heat-treating the gel to remove organic acids and by-products; and (d) drying the heat-treated gel to remove residual moisture.

First, the organic acid added in step (a) is a component that can gel the aminosilane-based salt compound and the silicate-based compound into a silica matrix structure through a chemical reaction. Examples of such organic acids include common organic acids such as formic acid, citric acid, oxalic acid, tannic acid, and mixtures thereof, and have low boiling points, making them difficult to remove during the drying process. Considering convenience, it may be desirable to apply formic acid as an organic acid.

The lithium salt-containing liquid electrolyte (deep eutectic solution; DES) used in step (a) is a liquid electrolyte containing a lithium salt and a liquefying agent, and serves to provide lithium salt to the solid electrolyte for a lithium secondary battery of the present invention. . In addition, the description of the aminosilane-based salt compound, silicate-based compound, and lithium salt-containing liquid electrolyte is replaced with the above.

The lithium salt-containing liquid electrolyte can be prepared by mixing the lithium salt and the liquefying agent at a certain ratio and then stirring for 1 to 5 hours, preferably 2 to 4 hours, under nitrogen purging (N ₂ purging) conditions. . In the liquid electrolyte containing the lithium salt, the mixing ratio of the liquefying agent and the lithium salt is 3 to 5:1 in molar ratio, preferably 3.5 to 4.5:1, and if the mixing ratio of the liquefying agent and the lithium salt is outside the above range, Problems may arise where unliquefied composition remains.

Meanwhile, the lithium salt-containing liquid electrolyte may be prepared before step (a) or simultaneously with step (a), and may be appropriately mixed with the aminosilane salt compound, silicate compound, and organic acid. There are no particular restrictions on the manufacturing order, as long as it is possible.

To manufacture the solid electrolyte for a lithium secondary battery, first, an aminosilane-based salt compound, a silicate-based compound, an organic acid, and a lithium salt-containing liquid electrolyte must be mixed (step a). The mixing ratio of the aminosilane-based salt compound, silicate-based compound, organic acid, and lithium salt-containing liquid electrolyte may be 0.05 to 0.5:0.5 to 0.95:5 to 13:3 to 7 in molar ratio, and the aminosilane-based salt compound, If the mixing ratio of the silicate compound, organic acid, and lithium salt-containing liquid electrolyte is outside the above range, problems such as failure to gel or decreased mechanical strength may occur.

After uniformly mixing the aminosilane-based salt compound, silicate-based compound, organic acid, and lithium salt-containing liquid electrolyte as described above, the mixed solution is allowed to stand and gelation is performed (step b). That is, the mixed solution in which the aminosilane-based salt compound, silicate-based compound, organic acid, and lithium salt-containing liquid electrolyte are uniformly mixed is supplied to a mold having the shape of the desired solid electrolyte, and is heated for 15 to 30 hours at room temperature. It may be left for an hour, preferably 20 to 28 hours, more preferably about 24 hours. However, it is specified that any substrate that can form a certain shape can be applied other than molds, and the leaving temperature or time can vary depending on process conditions, etc.

After the mixed solution is left to gel, the gel formed by gelling the mixed solution is heat treated to remove organic acids and by-products (step c). The heat treatment may be performed at 30 to 60°C, preferably 40 to 50°C, more preferably at about 45°C for 48 to 100 hours, preferably 60 to 90 hours, and more preferably 70 to 80 hours. , Through this, the organic acids that contributed to the gelation as well as other by-products such as ethanol and ethyl formate that may be generated during the reaction can be removed.

When the organic acid and by-products are removed through the heat treatment, the heat-treated gel is dried to remove remaining moisture (step d), thereby producing a solid electrolyte for a lithium secondary battery according to the present invention. The drying is carried out by vacuum drying at 70 to 90°C, preferably 75 to 85°C, more preferably about 80°C for 8 to 24 hours, preferably 12 to 20 hours, more preferably about 16 hours. This can be performed, and through this, a solid electrolyte is produced by completely removing the moisture remaining in the gel.

Meanwhile, the present invention provides a lithium secondary battery including a positive electrode, a negative electrode, a solid electrolyte for a lithium secondary battery and a separator interposed between the positive electrode and the negative electrode, where the lithium secondary battery refers to a lithium metal battery, a lithium sulfur battery, and It is desirable to interpret it as referring to all lithium secondary batteries known in the art, such as lithium air batteries. In addition, in the past, when manufacturing or assembling a battery (particularly a coin-cell), the internal electrolyte was subjected to pressure, which often resulted in leakage and crushing, but the present invention, unlike this, prevents the leakage of the solid electrolyte. It has the advantage of not forming and maintaining its shape well.

Furthermore, the present invention can also provide a battery module including a lithium secondary battery as a unit cell and a battery pack including the same. The battery module or battery pack includes a power tool; Electric vehicles, including electric vehicles (EV), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEV); Alternatively, it can be used as a power source for any one or more mid- to large-sized devices among power storage systems.

Hereinafter, a description of the positive electrode, negative electrode, and separator applied to the lithium secondary battery according to the present invention will be added.

anode

Regarding the positive electrode used in the present invention, a positive electrode composition containing a positive electrode active material, a conductive material, and a binder is prepared, and then the slurry prepared by diluting the positive electrode composition in a predetermined solvent (dispersion medium) is directly coated on the positive electrode current collector and An anode layer can be formed by drying. Alternatively, the positive electrode layer can be manufactured by casting the slurry on a separate support and then peeling the slurry from the support and laminating the obtained film onto the positive electrode current collector. In addition, the anode can be manufactured in various ways using methods widely known to those skilled in the art.

The conducting material not only provides electronic conductivity by acting as a path for electrons to move from the positive electrode current collector to the positive electrode active material, but also electrically connects the electrolyte and the positive electrode active material to prevent lithium ions (Li+) in the electrolyte. At the same time, it acts as a path that moves to sulfur and causes it to react. Therefore, if the amount of the conductive material is insufficient or does not perform its role properly, the unreacted portion of the sulfur in the electrode increases, ultimately causing a decrease in capacity. In addition, since it has a negative effect on high-rate discharge characteristics and charge-discharge cycle life, it is necessary to add an appropriate conductive material. The content of the conductive material is preferably added within the range of 0.01 to 30% by weight based on the total weight of the positive electrode composition.

The conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, graphite; Carbon black such as Denka Black, Acetylene Black, Ketjen Black, Channel Black, Furnace Black, Lamp Black and Summer Black; Conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used. Specific examples of commercially available conductive materials include acetylene black products from Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company products, Ketjenblack, and EC-based Armak. Armak Company products, Vulcan XC-72 Cabot Company products, and Super-P (Timcal Company products) can be used.

The binder is used to properly attach the positive electrode active material to the current collector, and must be well soluble in a solvent, form a conductive network between the positive electrode active material and the conductive material, and also have adequate impregnability of the electrolyte solution. The binder may be any binder known in the art, and specifically, a fluororesin binder containing polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); Rubber-based binders including styrene-butadiene rubber, acrylonitrile-butadiene rubber, and styrene-isoprene rubber; Cellulose-based binders including carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, and regenerated cellulose; polyalcohol-based binder; Polyolefin-based binders including polyethylene and polypropylene; It may be a mixture or copolymer of one or more types selected from the group consisting of polyimide-based binder, polyester-based binder, and silane-based binder, but is not limited thereto.

The content of the binder may be 0.5 to 30% by weight based on the total weight of the positive electrode composition, but is not limited thereto. If the content of the binder resin is less than 0.5% by weight, the physical properties of the positive electrode may deteriorate and the positive electrode active material and the conductive material may fall off, and if it exceeds 30% by weight, the ratio of the active material and the conductive material in the positive electrode is relatively reduced. Battery capacity may be reduced, and efficiency may be reduced by acting as a resistance element.

The positive electrode composition containing the positive electrode active material, conductive material, and binder may be diluted in a predetermined solvent and coated on the positive electrode current collector using a conventional method known in the art. First, prepare the positive electrode current collector. The positive electrode current collector is generally used to have a thickness of 3 to 500 ㎛. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, for example, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel. Surface treatment of steel with carbon, nickel, titanium, silver, etc. can be used. The current collector can increase the adhesion of the positive electrode active material by forming fine irregularities on its surface, and can be in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

Next, a slurry obtained by diluting a positive electrode composition containing a positive electrode active material, a conductive material, and a binder in a solvent is applied onto the positive electrode current collector. The positive electrode composition containing the above-described positive electrode active material, conductive material, and binder can be mixed with a predetermined solvent to prepare a slurry. At this time, the solvent must be easy to dry and be able to dissolve the binder well, but it is most desirable to maintain the positive electrode active material and the conductive material in a dispersed state without dissolving them. When the solvent dissolves the positive electrode active material, the specific gravity of sulfur in the slurry (D = 2.07) is high, so the sulfur settles in the slurry, causing sulfur to concentrate on the current collector during coating, causing problems in the conductive network and tending to cause problems in battery operation. There is. The solvent (dispersion medium) may be water or an organic solvent, and the organic solvent may be one or more selected from the group of dimethylformamide, isopropyl alcohol, acetonitrile, methanol, ethanol, and tetrahydrofuran.

Continuing, there is no particular limitation on the method of applying the positive electrode composition in the slurry state, for example, doctor blade coating, dip coating, gravure coating, and slit die coating. coating, spin coating, comma coating, bar coating, reverse roll coating, screen coating, cap coating, etc. It can be manufactured. The positive electrode composition that has undergone this coating process undergoes a subsequent drying process to achieve evaporation of the solvent (dispersion medium), density of the coating film, and adhesion between the coating film and the current collector. At this time, drying is carried out according to a conventional method and is not particularly limited.

cathode

Any cathode that can occlude and release lithium ions can be used. For example, metal materials such as lithium metal and lithium alloy, and carbon materials such as low-crystalline carbon and high-crystalline carbon can be used. Representative low-crystalline carbons include soft carbon and hard carbon, and high-crystalline carbons include natural graphite, Kish graphite, pyrolytic carbon, and liquid crystal pitch carbon fiber. (Mesophase pitch based carbon fiber), carbon microspheres (Meso-carbon microbeads), liquid crystal pitches (Mesophase pitches) and petroleum or coal-based coke (Petroleum or

High-temperature fired carbon such as coal tar pitch derived cokes is a representative example. In addition, alloys containing silicon and oxides such as Li4Ti5O12 are also well-known cathodes.

At this time, the cathode may include a binder, and the binder includes polyvinylidenefluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), and polyacrylonitrile. Various types of binder polymers can be used, such as polyacrylonitrile, polymethylmethacrylate, and styrene-butadiene rubber (SBR).

The negative electrode may optionally further include a negative electrode current collector to support the negative electrode active layer containing the negative electrode active material and a binder. The negative electrode current collector may be specifically selected from the group consisting of copper, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be surface treated with carbon, nickel, titanium, or silver, and an aluminum-cadmium alloy may be used as the alloy. In addition, calcined carbon, a non-conductive polymer surface-treated with a conductive agent, or a conductive polymer may be used.

The binder plays the role of pasting the negative electrode active material, mutual adhesion between active materials, adhesion between the active material and the current collector, and a buffering effect against expansion and contraction of the active material. Specifically, the binder is the same as previously described for the binder of the positive electrode. Additionally, the negative electrode may be lithium metal or lithium alloy. As a non-limiting example, the cathode may be a thin film of lithium metal, lithium and one selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al and Sn. It may be an alloy with the above metals.

separator

A conventional separator may be interposed between the anode and the cathode. The separator is a physical separator that has the function of physically separating electrodes, and can be used without particular restrictions as long as it is used as a normal separator. In particular, it is desirable to have low resistance to ion movement in the electrolyte and excellent electrolyte moisture ability. Additionally, the separator separates or insulates the positive and negative electrodes from each other and enables the transport of lithium ions between the positive and negative electrodes. These separators are porous and may be made of non-conductive or insulating materials. The separator may be an independent member such as a film, or may be a coating layer added to one or more of the anode and cathode. Specifically, porous polymer films, for example, porous polymer films made of polyolefin polymers such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer. It can be used alone or by laminating them, or a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, etc., can be used, but is not limited thereto.

Preferred examples are presented below to aid understanding of the present invention. However, the following examples are merely illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention. It is natural that such changes and modifications fall within the scope of the attached patent claims.

[Example 1] Preparation of solid electrolyte

First, N-methylacetamide (NMAC) as a liquefying agent and LiTFSI, a lithium salt, were mixed at a molar ratio of 4:1, and then purged with nitrogen and magnetically stirred for 3 hours to prepare a lithium salt-containing liquid electrolyte. Next, the prepared lithium salt-containing liquid electrolyte, the aminosilane salt compound trimethyl[3-(triethoxysilyl)propyl]ammonium chloride (TPAC), the silicate compound tetraethyl orthosilicate (TEOS), and formic acid. After mixing uniformly, the mixed solution was poured into a mold and left at room temperature for 24 hours to gel. Subsequently, the gel prepared by gelling the mixture was heat-treated at 45°C for 72 hours to remove formic acid and by-products. Finally, the heat-treated gel was vacuum dried at 80°C for 16 hours to remove the remaining gel contained in the gel. A solid electrolyte for a lithium secondary battery was prepared by removing moisture. Meanwhile, the mixing ratio of the aminosilane-based salt compound, silicate-based compound, formic acid, liquefying agent, and lithium salt was set to 0.1:0.9:8.7:4:1 as a molar ratio, and Figure 1 shows the solid electrolyte before being subjected to pressure (i.e., the above-mentioned electrolyte). This is an image showing the shape of the solid electrolyte prepared in Example 1.

[Example 2] Preparation of solid electrolyte

As an aminosilane salt compound, instead of trimethyl[3-(triethoxysilyl)propyl]ammonium chloride (TPAC), 3-ethyl-1-(3-triethoxysilyl)propyl)-imidazolium bis(trifluoro) A solid electrolyte was prepared in the same manner as in Example 1, except that methylsulfonyl)imide was used.

[Comparative Example 1] Preparation of solid electrolyte

A solid electrolyte was prepared in the same manner as in Example 1, except that trimethyl[3-(triethoxysilyl)propyl]ammonium chloride (TPAC), an aminosilane salt compound, was not used. Meanwhile, the mixing ratio of the silicate-based compound, formic acid, liquefying agent, and lithium salt was set to 1:8.7:4:1 as a molar ratio.

[Examples 3-4, Comparative Example 2] Production of coin-cell

A 2032 type coin cell was manufactured by interposing the solid electrolytes prepared in Examples 1 and 2 and Comparative Example 1 between 0.3 mm thick SUS electrodes.

[Experimental Example 1] Evaluation of ionic conductivity of solid electrolyte

The coin-cells manufactured in Examples 3 and 4 and Comparative Example 2 were connected with a two-electrode system to a room temperature chamber maintained at 25°C, and then an AC voltage of 10 mV was applied in the range of 1 Hz to 7 MHz to generate electricity. Chemical impedance (Electrochemical Impedance Spectroscopy) analysis was performed (at this time, the measured impedance was plotted as a nyquist plot (polar coordinate diagram or Nyquist diagram), and the first semicircle or part of the semicircle met the real impedance axis. The right end point was used as the resistance value of the electrolyte). After electrochemical impedance analysis, the coin-cell was disassembled to measure the thickness of the solid electrolyte membrane, and ionic conductivity was calculated using Equation 1 below (in Equation 1 below, t refers to the electrolyte thickness, and S is the electrode means the area, and R _b means electrolyte resistance (or ion resistance)), and the results are shown in Table 1 below.

[Formula 1]

Ion conductivity (S/cm) Example 3 3.8 × 10 ^-4 Comparative Example 2 4.0 × 10 ^-4

As a result of measuring the ionic conductivity values of the coin cells manufactured in Examples 3 and 4 and Comparative Example 2 using the above measurement method, the ionic conductivity values of all coin cells were very similar (Example 4 In this case, it was very similar to the ionic conductivity value of Example 3), through which it was found that even if an aminosilane salt compound was applied as an electrolyte material as in the present invention, there was no significant effect on ionic conductivity.

[Experimental Example 2] Evaluation of mechanical properties of solid electrolyte

In the process of manufacturing the coin-cell through Examples 3 and 4 and Comparative Example 2, the solid electrolyte was subjected to pressure, and the occurrence of leakage and crushing of each solid electrolyte was visually observed. As a result of the above observation, the solid electrolyte applied to the coin-cell of Comparative Example 2 caused both leakage and crushing, while the solid electrolyte of the present invention applied to the coin-cell of Examples 3 and 4 showed improvement in mechanical properties. As a result, it was confirmed that no leakage occurred and that the shape was maintained well.

Claims (15)

Aminosilane salt compounds;
silicate-based compounds; and
A gel-like solid electrolyte for a lithium secondary battery containing a lithium salt-containing liquid electrolyte. The solid electrolyte for a lithium secondary battery according to claim 1, wherein the aminosilane salt compound contains cations and anions. The method of claim 2, wherein the compound providing the cation is trimethyl[3-(triethoxysilyl)propyl]ammonium, 3-methyl-1-(3-triethoxysilyl)propyl)-imidazolium, 3-ethyl -1-(3-triethoxysilyl)propyl)-imidazolium, N-(3-triethoxysilyl)propyl-pyridinium, at least one selected from the group consisting of,
The compound providing the anion is at least one selected from the group consisting of halogen anion, bis(trifluoromethylsulfonyl)imide, and bis(fluorosulfonyl)imide,
A solid electrolyte for a lithium secondary battery, wherein the aminosilane salt compound is a mixture of at least one cation-donating compound and at least one anion-providing compound. The method of claim 3, wherein the aminosilane salt compound is trimethyl[3-(triethoxysilyl)propyl]ammonium chloride (TPAC), 3-ethyl-1-(3-triethoxysilyl)propyl)-imidazolium. At least one selected from the group consisting of bis(trifluoromethylsulfonyl)imide and 3-methyl-1-(3-triethoxysilyl)propyl)-imidazolium bis(fluorosulfonyl)imide. Characterized by solid electrolyte for lithium secondary batteries. The method according to claim 1, wherein the content of the aminosilane-based salt compound is 0.01 to 6% by weight, the content of the silicate-based compound is 4 to 10% by weight, and the content of the lithium salt-containing liquid electrolyte is 50 to 95% by weight. A solid electrolyte for a lithium secondary battery, characterized in that. The method according to claim 1, wherein the lithium salt-containing liquid electrolyte is a group consisting of N-methylacetamide (NMAC), urea, acetamide, 1-methyl urea, 1,3-dimethyl urea, 1,1-dimethyl urea, and thiourea. A solid electrolyte for a lithium secondary battery, characterized in that it contains one or more liquefying agents selected from and a lithium salt. The lithium secondary compound according to claim 1, wherein the silicate-based compound is at least one selected from the group consisting of tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), and tetraisopropyl orthosilicate. Solid electrolyte for batteries. (a) mixing an aminosilane-based salt compound, a silicate-based compound, an organic acid, and a lithium salt-containing liquid electrolyte;
(b) gelling the mixed solution by leaving it alone;
(c) heat treating the gel to remove organic acids and by-products; and
(d) drying the heat-treated gel to remove remaining moisture. The method of claim 8, wherein the organic acid is selected from the group consisting of formic acid, citric acid, oxalic acid, tannic acid, and mixtures thereof. The method of claim 8, wherein the mixed solution in step (b) is supplied to the mold and left at room temperature for 15 to 30 hours. The method of claim 8, wherein the heat treatment is performed at 30 to 60° C. for 48 to 100 hours. The method of claim 8, wherein the drying is performed at 70 to 90° C. for 8 to 24 hours. The method according to claim 8, wherein the mixing ratio of the aminosilane salt compound, silicate compound, organic acid, and lithium salt-containing liquid electrolyte is 0.05 ~ 0.5 : 0.5 ~ 0.95 : 5 ~ 13 : 3 ~ 7 in molar ratio. Method for manufacturing solid electrolyte for lithium secondary battery. anode; cathode; The solid electrolyte for a lithium secondary battery of claim 1 interposed between the positive electrode and the negative electrode; A lithium secondary battery comprising a separator. The lithium secondary battery according to claim 14, wherein the lithium secondary battery is selected from the group consisting of a lithium metal battery, a lithium sulfur battery, and a lithium air battery.