JP2015197975A - Secondary battery negative electrode and method for manufacturing the same, and secondary battery using the secondary battery negative electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative electrode that provides a nonaqueous electrolyte secondary battery excellent in cycle characteristics and storage characteristics.SOLUTION: The present invention relates to a secondary battery negative electrode containing at least one vinyl ether compound and a secondary battery using the secondary battery negative electrode.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery. More specifically, the present invention relates to a lithium secondary battery or a lithium ion secondary battery, and in particular, a secondary battery negative electrode capable of improving the problems of charge / discharge cycle life, capacity retention characteristics, and resistance increase of the secondary battery, and its manufacture. The present invention relates to a method and a non-aqueous electrolyte secondary battery using the method.

  Non-aqueous electrolyte lithium which uses carbon material, oxide, lithium alloy or lithium metal for negative electrode, uses lithium-containing transition metal composite oxide for positive electrode, and further has electrolyte containing chain or cyclic carbonate solvent Ion or lithium secondary batteries are attracting attention as power sources for mobile phones and laptop computers because they can achieve high energy density. Recently, attention has also been paid to a power source for driving a motor such as a hybrid vehicle (HEV) by improving output characteristics and long-term reliability such as storage characteristics. In these secondary batteries, for the purpose of suppressing the reaction between the negative electrode surface and the solvent molecules, a plurality of additives are added to the electrolytic solution, and an electrochemical reaction in the charge / discharge process is used to add the additives to the negative electrode surface. It is known to improve the basic characteristics and reliability of a secondary battery by forming a film called a protective film (or coating, SEI). This coating has a significant effect on charge and discharge efficiency, cycle life, and safety, so it is known that formation and control of the coating on the negative electrode surface is indispensable for improving battery performance. The secondary battery used for the liquid exhibits very excellent battery characteristics.

  However, it has the following problems. When a film-forming additive is added to the electrolytic solution, the electrolytic solution contacts not only the negative electrode but also the positive electrode, so that a decomposition product of the additive is generated by oxidative decomposition on the positive electrode surface. When the decomposition product of the additive is eluted into the electrolytic solution, the viscosity of the electrolytic solution is increased and the ionic conductivity is decreased, so that the battery characteristics are deteriorated. In addition, all the additives in the electrolytic solution remain without being consumed even after the film is formed in the charge / discharge process, so that a new film grows by repeated charge / discharge, the internal resistance of the negative electrode increases, and the battery characteristics are improved. descend. Furthermore, the film-forming additive is generally highly reactive and has a problem of poor storage stability in the electrolytic solution.

  As a solution to this problem, as shown in Patent Document 1, 0.5 to 20% by mass of a film forming additive is added to the negative electrode slurry, and the negative electrode manufactured using this slurry is converted into a nonaqueous electrolytic solvent. A method for producing an electrode is known in which an SEI film is formed on the surface of a negative electrode by charging and discharging in the inside, whereby an additive remaining in a nonaqueous electrolytic solution can be reduced after the film is formed. In addition, Patent Document 2 adds an additive capable of forming a solid electrolyte interface layer to the negative electrode when charging and discharging the battery to the negative electrode active material slurry composition for a lithium secondary battery. It is described that gas generation can be suppressed.

JP 2010-199043 A JP 2003-263388 A

  However, as described in Patent Document 1 and Patent Document 2, when an electrode is manufactured by adding a film-forming additive to the negative electrode slurry, depending on the compound used as the film-forming additive and the amount added, an electrolytic solution In this case, the additive may dissolve and cause the above-described deterioration in battery characteristics. In addition, depending on the film forming additive, the dispersion state of the slurry is changed, and when the slurry is produced, the slurry becomes non-uniform and may become non-uniform slurry, which makes it impossible to produce a uniform negative electrode. Furthermore, when a large amount of additive adheres to the binder, there is a problem that the binding effect is weakened, the adhesion between the negative electrode and the current collector is lowered, leading to a reduction in cycle life and capacity deterioration.

  This invention is made | formed in view of the said situation, The objective is to control the negative electrode surface of a secondary battery, and the surface vicinity by a membrane | film | coat, and to provide the technique which suppresses decomposition | disassembly of electrolyte solution solvent. Another object of the present invention is to provide a technique for improving the cycle life and capacity storage characteristics of a secondary battery. Another object of the present invention is to provide a non-aqueous electrolyte secondary battery excellent in characteristics for suppressing an increase in resistance.

  One aspect of the present invention relates to a negative electrode for a secondary battery, comprising at least one selected from the group consisting of vinyl ether compounds represented by the following formula (1) or formula (2).

（式（１）中、Ｒ_１は、−Ｃ_ａＨ_２ａＯＨ（ａは１〜１０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｂＨ（ｂは２〜１０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｃ−Ｃ_ｄＨ_２ｄ＋１（ｃは１〜１０の整数、ｄは１〜５の整数）、シクロヘキシル基、フェニル基または−Ｃ_ｅＨ_２ｅ＋１（ｅは１〜２０の整数、ただし、−Ｃ_ｅＨ_２ｅ＋１の水素原子の少なくとも一部がフッ素原子で置換されていてもよく、また、−Ｃ_ｅＨ_２ｅ＋１は直鎖であっても分岐鎖であってもよい）である。）

(In the formula (1), _{R 1 is,} -C _a H 2a OH (a is an integer of from 1 to _{10), - (CH 2 CH 2} O) b H (b is 2-10 integer), - (CH _{2 CH 2 O) c -C d} H 2d + 1 (c is an integer of from 1 to 10, d is an integer of from 1 to 5), a cyclohexyl group, a phenyl group or _-C e _{H 2e +} 1 (e is an integer of 1 to 20, provided that , -C _e H _{2e + 1} may be substituted with a fluorine atom, and -C _e H _{2e + 1} may be linear or branched).

（式（２）中、Ｒ_２は、−Ｃ_ｆＨ_２ｆ−（ｆは１〜２０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｇ−ＣＨ_２ＣＨ_２−（ｇは１〜１０の整数）、−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−、−Ｃ_ｈＨ_２ｈ−Ｏ−ＣＯ−Ｃ_６Ｈ_４−ＣＯ−Ｏ−Ｃ_ｉＨ_２ｉ−（ｈおよびｉはそれぞれ独立に１〜１０の整数）、−Ｃ_ｊＨ_２ｊ−Ｏ−ＣＯ−ＮＨ−Ｃ_ｋＨ_２ｋ−ＮＨ−ＣＯ−Ｏ−Ｃ_ｌＨ_２ｌ−（ｊ、ｋおよびｌはそれぞれ独立に１〜１０の整数）、−Ｃ_ｍＨ_２ｍ−Ｏ−ＣＯ−Ｃ_ｎＨ_２ｎ−ＣＯ−Ｏ−Ｃ_ｐＨ_２ｐ−（ｍ、ｎおよびｐはそれぞれ独立に１〜１０の整数）、−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−Ｏ−ＣＯ−Ｃ_ｑＨ_２ｑ−ＣＯ−Ｏ−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−（ｑは１〜１０の整数）または−Ｃ_ｒＨ_２ｒ−Ｏ−ＣＯ−Ｏ−Ｃ_ｓＨ_２ｓ−（ｒおよびｓはそれぞれ独立に１〜１０の整数）である。）

(In the formula (2), _{R 2 is,} -C _{f H 2f} - _(f is an integer of 1 to _{20), - (CH 2 CH 2} O) g -CH 2 CH 2 - (g is an integer of from 1 to 10 _{), - CH 2 -C 6 H} 10 -CH 2 -, - C h H 2h -O-CO-C 6 H 4 -CO-O-C i H 2i - (1~10 h and i are each independently _{integer) of, - C j H 2j -O-} CO-NH-C k H 2k -NH-CO-O-C l H 2l - (j, k and l are each independently an integer of 1 to 10), - _{C m H 2m -O-CO-} C n H 2n -CO-O-C p H 2p - (m, n and p each independently of 1 to 10 _{integer), - CH 2 -C 6 H} 10 -CH _{2 -O-CO-C q H} 2q -CO-O-CH 2 -C 6 H 10 -CH 2 - (q is an integer of from 1 to 10) or _-C r _{H 2 r -O-CO-O-C} s H 2s - (r and s are each independently an integer from 1 to 10) is).

  ADVANTAGE OF THE INVENTION According to this invention, the non-aqueous-electrolyte secondary battery in which the fall of cycling characteristics and the raise of internal resistance were suppressed can be provided.

It is typical sectional drawing which shows the structure of the electrode element used for a lamination | stacking laminate type secondary battery.

  Hereinafter, examples of the electrode of the present invention and a secondary battery in which this electrode can be used will be described for each component.

[1] Negative Electrode / Negative Electrode Active Material Layer The negative electrode is configured, for example, by binding a negative electrode active material to a negative electrode current collector with a negative electrode binder. As long as the negative electrode active material in this embodiment can occlude and release lithium, any material can be used as long as the effects of the present invention are not significantly impaired. The negative electrode is formed by providing a negative electrode active material layer on a current collector.

  The negative electrode active material is not particularly limited as long as it is a material capable of occluding and releasing lithium ions, and a known negative electrode active material can be arbitrarily used. For example, carbonaceous materials such as coke, acetylene black, mesophase microbeads, and graphite; lithium metal; lithium alloys such as lithium-silicon and lithium-tin, and lithium titanate are preferably used. Among these, it is most preferable to use a carbonaceous material in terms of good cycle characteristics and safety and excellent continuous charge characteristics. In addition, a negative electrode active material may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Further, the particle size of the negative electrode active material is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 1 μm or more, preferably 15 μm in terms of excellent battery characteristics such as initial efficiency, rate characteristics, and cycle characteristics. These are usually 50 μm or less, preferably about 30 μm or less. In addition, for example, those obtained by coating the above carbonaceous material with an organic substance such as pitch and then firing, those obtained by forming amorphous carbon on the surface using the CVD method, etc. It can be suitably used as a quality material. Here, organic substances used for coating include coal tar pitch from soft pitch to hard pitch; coal heavy oil such as dry distillation liquefied oil; straight heavy oil such as atmospheric residual oil and vacuum residual oil; crude oil And petroleum heavy oils such as cracked heavy oil (for example, ethylene heavy end) produced as a by-product during thermal decomposition of naphtha and the like. Moreover, what grind | pulverized the solid residue obtained by distilling these heavy oils at 200-400 degreeC to 1-100 micrometers can also be used. Furthermore, a vinyl chloride resin, a phenol resin, an imide resin, etc. can also be used. For example, the negative electrode active material layer can be formed into a sheet electrode by roll molding the negative electrode active material described above, or a pellet electrode by compression molding. Usually, as in the case of the positive electrode active material layer, The negative electrode active material, the binder, and, if necessary, various auxiliary agents and the like can be produced by applying a coating solution obtained by slurrying with a solvent onto a current collector and drying it. it can.

  Examples of the negative electrode active material containing silicon include silicon and silicon compounds. Examples of silicon include simple silicon. Examples of the silicon compound include silicon oxide, silicate, a compound of transition metal such as nickel silicide and cobalt silicide and silicon, and the like. The silicon compound has a role of relaxing expansion and contraction due to repeated charge / discharge of the negative electrode active material itself, and is preferably used from the viewpoint of charge / discharge cycle characteristics. Furthermore, depending on the type of silicon compound, it also has a role of ensuring conduction between silicons. From this point of view, silicon oxide is preferably used as the silicon compound. The silicon oxide is not particularly limited, but is represented by, for example, SiOx (0 <x <2). The silicon oxide may contain Li, and the silicon oxide containing Li is represented by, for example, SiLiyOz (y> 0, 2> z> 0). Further, the silicon oxide may contain a trace amount of a metal element or a nonmetal element. The silicon oxide can contain, for example, 0.1 to 5% by mass of one or more elements selected from nitrogen, boron and sulfur. By containing a trace amount of a metal element or a nonmetal element, the electrical conductivity of the silicon oxide can be improved. Further, the silicon oxide may be crystalline or amorphous. The negative electrode active material preferably contains a carbon material capable of inserting and extracting lithium ions in addition to silicon or silicon oxide. The carbon material can also be contained in a composite state with silicon or silicon oxide. Similar to silicon oxide, the carbon material has the role of relaxing expansion and contraction due to repeated charge and discharge of the negative electrode active material itself and ensuring conduction between silicon as the negative electrode active material. Therefore, better cycle characteristics can be obtained by the coexistence of silicon, silicon oxide, and carbon material.

  As the carbon material, graphite, amorphous carbon, diamond-like carbon, carbon nanotube, or a composite thereof can be used. Here, graphite with high crystallinity has high electrical conductivity, and is excellent in adhesiveness and voltage flatness with a negative electrode current collector made of a metal such as copper. On the other hand, since amorphous carbon having low crystallinity has a relatively small volume expansion, it has a high effect of relaxing the volume expansion of the entire negative electrode, and deterioration due to non-uniformity such as crystal grain boundaries and defects hardly occurs. The content of the carbon material in the negative electrode active material is preferably 2% by mass or more and 50% by mass or less, and more preferably 2% by mass or more and 30% by mass or less.

  As a method for producing a negative electrode active material containing silicon and a silicon compound, when silicon oxide is used as the silicon compound, for example, a method of mixing simple silicon and silicon oxide and sintering under high temperature and reduced pressure Is mentioned. Further, when a compound of transition metal and silicon is used as the silicon compound, for example, a method of mixing and melting simple silicon and the transition metal, and a method of coating the transition metal on the surface of the simple silicon by vapor deposition or the like can be mentioned. .

  In addition to the manufacturing method described above, the compounding with carbon can be combined. For example, a method of introducing a mixed sintered product of simple silicon and silicon compound into a gas atmosphere of an organic compound in a high temperature non-oxygen atmosphere, or a mixed sintered product of single silicon and silicon oxide and carbon in a high temperature non-oxygen atmosphere. By the method of mixing the precursor resins, a coating layer made of carbon can be formed around the cores of simple silicon and silicon oxide. Thereby, the suppression of volume expansion with respect to charging / discharging and the further improvement effect of cycling characteristics are acquired.

  When silicon is used as the negative electrode active material in the present embodiment, the negative electrode active material is preferably composed of a composite containing silicon, silicon oxide, and a carbon material (hereinafter also referred to as Si / SiO / C composite). Furthermore, it is preferable that all or part of the silicon oxide has an amorphous structure. The silicon oxide having an amorphous structure can suppress the volume expansion of a carbon material or silicon which is another negative electrode active material. Although this mechanism is not clear, it is presumed that the formation of a film on the interface between the carbon material and the electrolytic solution has some influence due to the amorphous structure of silicon oxide. The amorphous structure is considered to have relatively few elements due to non-uniformity such as crystal grain boundaries and defects. Note that it can be confirmed by X-ray diffraction measurement (general XRD measurement) that all or part of silicon oxide has an amorphous structure. Specifically, when silicon oxide does not have an amorphous structure, a peak peculiar to silicon oxide is observed, but when all or part of silicon oxide has an amorphous structure, silicon oxide is observed. A unique peak is observed as a broad peak.

  In the Si / SiO / C composite, it is preferable that all or part of silicon is dispersed in silicon oxide. By dispersing at least a part of silicon in silicon oxide, volume expansion as a whole of the negative electrode can be further suppressed, and decomposition of the electrolytic solution can also be suppressed. Note that all or part of silicon is dispersed in the silicon oxide because transmission electron microscope observation (general TEM observation) and energy dispersive X-ray spectroscopy measurement (general EDX measurement). It can confirm by using together. Specifically, the cross section of the sample is observed, the oxygen concentration of the silicon portion dispersed in the silicon oxide is measured, and it can be confirmed that the sample is not an oxide.

  In the Si / SiO / C composite, for example, all or part of silicon oxide has an amorphous structure, and all or part of silicon is dispersed in silicon oxide. Such a Si / SiO / C composite can be produced, for example, by a method disclosed in Japanese Patent Application Laid-Open No. 2004-47404. That is, the Si / SiO / C composite can be obtained, for example, by performing a CVD process on silicon oxide in an atmosphere containing an organic gas such as methane gas. The Si / SiO / C composite obtained by such a method has a form in which the surface of particles made of silicon oxide containing silicon is coated with carbon. Silicon is nanoclustered in silicon oxide.

  In the Si / SiO / C composite, the ratio of silicon, silicon oxide and carbon material is not particularly limited. Silicon is preferably 5% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 50% by mass or less with respect to the Si / SiO / C composite. The silicon oxide is preferably 5% by mass or more and 90% by mass or less, and more preferably 40% by mass or more and 70% by mass or less with respect to the Si / SiO / C composite. The carbon material is preferably 2% by mass or more and 50% by mass or less, and more preferably 2% by mass or more and 30% by mass or less with respect to the Si / SiO / C composite.

  Further, the Si / SiO / C composite can be composed of a mixture of simple silicon, silicon oxide and carbon material, and can also be produced by mixing simple silicon, silicon oxide and carbon material by mechanical milling. it can. For example, the Si / SiO / C composite can be obtained by mixing particulate silicon, silicon oxide and carbon materials. For example, the average particle diameter of simple silicon can be made smaller than the average particle diameter of the carbon material and the average particle diameter of the silicon oxide. In this way, single silicon having a large volume change during charge / discharge has a relatively small particle size, and carbon materials and silicon oxides having a small volume change have a relatively large particle size. Is more effectively suppressed.

  Moreover, the average particle diameter of single-piece | unit silicon can be 20 micrometers or less, for example, and it is preferable to set it as 15 micrometers or less. The average particle diameter of silicon oxide is preferably 1/2 or less of the average particle diameter of the carbon material, and the average particle diameter of simple silicon is 1/2 or less of the average particle diameter of silicon oxide. preferable.

  Furthermore, it is more preferable that the average particle diameter of the silicon oxide is 1/2 or less of the average particle diameter of the carbon material, and the average particle diameter of the simple silicon is 1/2 or less of the average particle diameter of the silicon oxide. . By controlling the average particle diameter in such a range, the effect of relaxing the volume expansion can be obtained more effectively, and a secondary battery excellent in the balance of energy density, cycle life and efficiency can be obtained. More specifically, it is preferable that the average particle diameter of silicon oxide is ½ or less of the average particle diameter of graphite, and the average particle diameter of simple silicon is ½ or less of the average particle diameter of silicon oxide. . More specifically, the average particle diameter of the single silicon can be, for example, 20 μm or less, and is preferably 15 μm or less. Moreover, you may use what processed the surface of the above-mentioned Si / SiO / C composite_body | complex with a silane coupling agent as a negative electrode active material.

-Negative electrode binder The negative electrode binder is not particularly limited, and examples thereof include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-tetrafluoroethylene copolymer. Polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamideimide, various polyurethanes, and the like can be used. Among these, polyvinylidene fluoride, polyimide, and polyamideimide having excellent chemical resistance in addition to good mechanical, thermal, and electrical properties are preferable.

  An aqueous binder can also be used. The aqueous binder is not particularly limited, but usually, a water-dispersible polymer is used in the form of a latex or an emulsion. For example, an acrylic resin emulsion, a styrene resin emulsion, a vinyl acetate polymer emulsion, a urethane resin emulsion, or the like can be used. Among these, a water-dispersible synthetic rubber latex or emulsion is preferable from the viewpoint of viscoelastic properties. Examples of the water-dispersible synthetic rubber latex (emulsion) include polybutadiene rubber latex, styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, (meth) acrylic acid ester-butadiene rubber latex, chloroprene rubber latex, and the like. Styrene-butadiene rubber latex (SBR latex) is preferable from the viewpoint of resistance to the electrolytic solution.

  These binders can be used alone or in admixture of two or more. The amount of the binder for the negative electrode to be used is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material from the viewpoints of “sufficient binding force” and “high energy” which are in a trade-off relationship. .

-Thickener for negative electrode In order to make it easy to produce a negative electrode slurry, a thickener can also be used. Such thickeners include carboxymethylcellulose (including alkali neutralized lithium, sodium and potassium salts), polyethylene oxide, polypropylene oxide, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylhydroxyethylcellulose, polyvinyl alcohol. , Polyacrylamide, hydroxyethyl polyacrylate, ammonium polyacrylate, polyacrylic acid (including lithium salt, sodium salt and potassium salt neutralized with alkali). These thickeners can be used alone or in admixture of two or more. As a ratio of the thickener in an electrode, 0.1-5 mass% is preferable with respect to a negative electrode active material.

-Surfactant for negative electrode When water is used as the dispersion solvent, a nonionic surfactant can also be used for the purpose of improving the dispersibility of the carbon particles in the slurry. Although it does not specifically limit as a nonionic surfactant, Polyoxyalkylene alkyl ether can be used preferably. The polyoxyalkylene alkyl ether is represented by the general formula: R—O— (AO) _n H (wherein R represents an alkyl group, A represents an alkylene group, and n represents a natural number). Here, the carbon number of the alkyl group represented by the symbol R, the carbon number of the alkylene group represented by the symbol A, and the degree of polymerization of the alkyleneoxy group (AO) represented by n are not particularly limited. The polyoxyalkylene alkyl ether is different in at least one of the number of carbon atoms of the alkyl group represented by the symbol R, the number of carbon atoms of the alkylene group represented by the symbol A, and the degree of polymerization of the alkyleneoxy group (AO) represented by the symbol n. A mixture of polyoxyalkylene alkyl ethers may be used.

-Film-forming additive In the present invention, the negative electrode contains at least one vinyl ether compound. Note that in this specification, the vinyl ether compound represents a compound having one or more vinyloxy groups (—O—CH═CH ₂ ) in the molecule. Especially, it is preferable that a negative electrode contains at least 1 sort (s) chosen from the vinyl ether compound represented by following formula (1) or following formula (2). Hereinafter, the vinyl ether compound represented by the formula (1) or the formula (2) may be simply referred to as “vinyl ether compound”.

（式（１）中、Ｒ_１は、−Ｃ_ａＨ_２ａＯＨ（ａは１〜１０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｂＨ（ｂは２〜１０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｃ−Ｃ_ｄＨ_２ｄ＋１（ｃは１〜１０の整数、ｄは１〜５の整数）、シクロヘキシル基、フェニル基、または−Ｃ_ｅＨ_２ｅ＋１（ｅは１〜２０の整数、ただし、−Ｃ_ｅＨ_２ｅ＋１の水素原子の少なくとも一部がフッ素原子で置換されていてもよく、また、−Ｃ_ｅＨ_２ｅ＋１は直鎖であっても分岐鎖であってもよい）である。）

(In the formula (1), _{R 1 is,} -C _a H 2a OH (a is an integer of from 1 to _{10), - (CH 2 CH 2} O) b H (b is 2-10 integer), - (CH _{2 CH 2 O) c -C d} H 2d + 1 (c is an integer of from 1 to 10, d is an integer of from 1 to 5), a cyclohexyl group, a phenyl group or _-C e _{H 2e +} 1 (e is an integer of 1 to 20, However, at least part of the hydrogen atoms of -C _e H _{2e + 1} may be substituted with fluorine atoms, and -C _e H _{2e + 1} may be linear or branched). )

（式（２）中、Ｒ_２は、−Ｃ_ｆＨ_２ｆ−（ｆは１〜２０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｇ−ＣＨ_２ＣＨ_２−（ｇは１〜１０の整数）、−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−、−Ｃ_ｈＨ_２ｈ−Ｏ−ＣＯ−Ｃ_６Ｈ_４−ＣＯ−Ｏ−Ｃ_ｉＨ_２ｉ−（ｈおよびｉはそれぞれ独立に１〜１０の整数）、−Ｃ_ｊＨ_２ｊ−Ｏ−ＣＯ−ＮＨ−Ｃ_ｋＨ_２ｋ−ＮＨ−ＣＯ−Ｏ−Ｃ_ｌＨ_２ｌ−（ｊ、ｋおよびｌはそれぞれ独立に１〜１０の整数）、−Ｃ_ｍＨ_２ｍ−Ｏ−ＣＯ−Ｃ_ｎＨ_２ｎ−ＣＯ−Ｏ−Ｃ_ｐＨ_２ｐ−（ｍ、ｎおよびｐはそれぞれ独立に１〜１０の整数）、−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−Ｏ−ＣＯ−Ｃ_ｑＨ_２ｑ−ＣＯ−Ｏ−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−（ｑは１〜１０の整数）または−Ｃ_ｒＨ_２ｒ−Ｏ−ＣＯ−Ｏ−Ｃ_ｓＨ_２ｓ−（ｒおよびｓは、それぞれ独立に１〜１０の整数）である。）

(In the formula (2), _{R 2 is,} -C _{f H 2f} - _(f is an integer of 1 to _{20), - (CH 2 CH 2} O) g -CH 2 CH 2 - (g is an integer of from 1 to 10 _{), - CH 2 -C 6 H} 10 -CH 2 -, - C h H 2h -O-CO-C 6 H 4 -CO-O-C i H 2i - (1~10 h and i are each independently _{integer) of, - C j H 2j -O-} CO-NH-C k H 2k -NH-CO-O-C l H 2l - (j, k and l are each independently an integer of 1 to 10), - _{C m H 2m -O-CO-} C n H 2n -CO-O-C p H 2p - (m, n and p each independently of 1 to 10 _{integer), - CH 2 -C 6 H} 10 -CH _{2 -O-CO-C q H} 2q -CO-O-CH 2 -C 6 H 10 -CH 2 - (q is an integer of from 1 to 10) or _-C r _{H 2 r -O-CO-O-C} s H 2s - (r and s are each independently an integer from 1 to 10) is).

In the monofunctional vinyl ether compound (monovinyl ether compound) represented by the formula (1), as R ₁ , —C _a H _2a OH (a is an integer of 1 to 10), — (CH ₂ CH ₂ O) _b H (B is an integer of 2 to 10), — (CH ₂ CH ₂ O) _c —C _d H _{2d + 1} (c is an integer of 1 to 10, d is an integer of 1 to 5), a cyclohexyl group, a phenyl group, and —C _e H _{2e + 1} (e is an integer of 1 to 20, provided that at least part of the hydrogen atoms of —C _e H _{2e + 1} may be substituted with fluorine atoms, and —C _e H _{2e + 1} is a straight chain, May also be branched).

In Formula (1), when R ₁ is —C _a H _2a OH, a is an integer of 1 to 10, and preferably an integer of 1 to 5. Examples of the alkylene group represented by —C _a H _2a — include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, etc., and —C _a H _2a — is branched even if it is linear. It may be a chain.

In Formula (1), when R ₁ is — (CH ₂ CH ₂ O) _b H, b is an integer of 2 to 10, and preferably an integer of 2 to 6.

In Formula (1), when R ₁ is — (CH ₂ CH ₂ O) _c —C _d H _{2d + 1} , c is an integer of 1 to 10, preferably an integer of 2 to 6, and d Is an integer of 1 to 5, preferably an integer of 1 to 3.

In the formula (1), R ₁ may be a cyclohexyl group (—C ₆ H ₁₁ ) or a phenyl group (—C ₆ H ₅ ).

In Formula (1), when R ₁ is an alkyl group represented by -C _e H _{2e + 1} , e is an integer of 1 to 20, and preferably an integer of 1 to 8. In addition, —C _e H _{2e + 1} may be a fluorinated alkyl group in which at least a part of hydrogen atoms is substituted with fluorine atoms, and the substitution position and the number of substitutions of fluorine atoms are arbitrary. When —C _e H _{2e + 1} is a fluorinated alkyl group, e is more preferably an integer of 1 to 3, and e is more preferably 2 or 3. Examples of fluorinated alkyl groups include, but are not limited to, —CH ₂ CF ₃ , —CH ₂ CH ₂ CF ₃ , —CH ₂ CF ₂ CF ₃ , —CF ₂ CF ₂ CF _{3 and the} like. The alkyl group or fluorinated alkyl group represented by —C _e H _{2e + 1} may be linear or branched. When e is an integer of 1 to 3, —C _e H _{2e + 1} may be an unsubstituted alkyl group or a fluorinated alkyl group, but more preferably a fluorinated alkyl group.

In the present embodiment, preferable examples of R ₁ include -C _a H _2a OH (a is an integer of 1 to 5),-(CH ₂ CH ₂ O) _b H (b is an integer of 2 to 6),- _{(CH 2 CH 2 O) c} -C d H 2d + 1 (c is an integer of from 2 to 6, d is an integer of 1 to _{3), - C e H 2e +} 1 (e is an integer of 1 to 3, of the formula And at least one hydrogen atom is substituted with a fluorine atom), but is not limited thereto.

In the divinyl ether compound represented by the formula (2), R ₂ includes —C _f H _2f — (f is an integer of 1 to 20), — (CH ₂ CH ₂ O) _g —CH ₂ CH ₂ — ( g is an integer of 1 to 10), —CH ₂ —C ₆ H ₁₀ —CH ₂ —, —C _h H _2h —O—CO—C ₆ H ₄ —CO—O—C _i H _2i — (h and i each independently an integer of 1 to _{10) are, - C j H 2j -O-} CO-NH-C k H 2k -NH-CO-O-C l H 2l - (1 j, k and l are each independently 10 _{integer), - C m H 2m -O} -CO-C n H 2n -CO-O-C p H 2p - (m, n and p are each independently an integer of 1 to 10), - CH _{2 -C 6 H 10 -CH 2 -O-} CO-C q H 2q -CO-O-CH 2 -C 6 H 10 -CH 2 - (q is an integer of from 1 to 10) and _{-C r H 2r -O-CO-} O-C s H 2s - (r and s are each independently an integer of 1 to 10), and the like.

In the formula (2), _{R 2} is _-C f _{H 2f} - when, f is an integer of 1 to 20, preferably an integer from 1 to 6. Examples of the alkylene group represented by —C _f H _2f — include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, etc., and —C _f H _2f — is branched even if it is linear. It may be a chain.

In the formula (2), _{R 2} is _{- (CH 2 CH 2 O)} g -CH 2 CH 2 - when, g is an integer of 1 to 10, is preferably an integer from 1 to 6.

In the formula (2), when R ₂ is —CH ₂ —C ₆ H ₁₀ —CH ₂ —, —C ₆ H ₁₀ — represents a cyclohexylene group, and represents 1,2-, 1,3-, 1, Although it may be substituted at any of the 4-positions, it is preferably substituted at the 1,4-positions.

In Formula (2), when R ₂ is —C _h H _2h —O—CO—C ₆ H ₄ —CO—O—C _i H _2i —, h and i are each independently an integer of 1 to 10 It is preferable that it is an integer of 1-6. The alkylene group represented by -C _h H _2h -or -C _i H _2i- may be linear or branched, and -C _h H _2h -and -C _i H _2i- May be the same or different. —C ₆ H ₄ — represents a phenylene group, which may be substituted at any of the ortho, meta, and para positions, but more preferably substituted at the para position.

In formula (2), when R ₂ is —C _j H _2j —O—CO—NH—C _k H _2k —NH—CO—O—C ₁ H _2l —, j, k and l are each independently It is an integer of 1 to 10, and preferably an integer of 1 to 6. The alkylene group represented by —C _j H _2j —, —C _k H _2k — or —C ₁ H _2l — may be linear or branched, and —C _j H _2j — , _-C k _{H 2k} - and _-C l _{H 2l} - may be be the same or different from each other.

In Formula (2), when R ₂ is —C _m H _2m —O—CO—C _n H _2n —CO—O—C _p H _2p —, m, n and p are each independently 1 to 10 It is an integer of 1 and it is preferable that it is an integer of 1-6. _{-C m H 2m -, - C} n H 2n - and _-C p _{H 2p} - alkylene group represented by may be branched be linear, also be the same as each other It may be different.

In the formula (2), when R ₂ is —CH ₂ —C ₆ H ₁₀ —CH ₂ —O—CO—C _q H _2q —CO—O—CH ₂ —C ₆ H ₁₀ —CH ₂ —, q is It is an integer of 1 to 10, and preferably an integer of 1 to 6. -C _q H _2q - can be straight chain or may be branched. —C ₆ H ₁₀ — represents a cyclohexylene group, which may be substituted at any of the 1,2-, 1,3- and 1,4-positions, but is substituted at the 1,4-position. It is preferable.

In Formula (2), when R ₂ is —C _r H _2r —O—CO—O—C _S H _2s —, r and s are each independently an integer of 1 to 10, It is preferably an integer. The alkylene groups represented by —C _r H _2r — and —C _s H _2s — may be linear or branched, and may be the same or different from each other.

In the present embodiment, preferable examples of R ₂ include — (CH ₂ CH ₂ O) _g —CH ₂ CH ₂ — (g is an integer of 1 to 6) and —C _h H _2h —O—CO—C _6. H ₄ —CO—O—C _i H _2i — (h and i are each independently an integer of 1 to 6) and the like can be mentioned, but are not limited thereto.

The vinyl ether compound that can be used in this embodiment can be synthesized by a general chemical reaction. Reactions with hydroxyl groups in vinyl ether, such as 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, etc., as a raw material, such as urethane reaction, etherification reaction, esterification reaction, carbonate reaction , Etc., various vinyl ether compounds can be synthesized. For example, bis [4- (vinyloxy) butyl] isophthalate can be synthesized by the reaction of isophthalic acid and 4-hydroxybutyl vinyl ether. In addition, a fluorine-containing vinyl ether compound can be synthesized by reacting 2-chloroethyl vinyl ether with a fluorine-containing alcohol in the presence of a palladium catalyst and an aliphatic amine. For example, 2,2,2-trifluoroethyl vinyl ether can be synthesized by a reaction of 2-chloroethyl vinyl ether and trifluoroethanol (HO—CH ₂ CF ₃ ).

  A vinyl ether compound may be used independently and may be used in combination of 2 or more type.

Among vinyl ether compounds, vinyl ether compounds having an ester group or a carbonate group with high affinity with the electrolytic solution, vinyl ether compounds having an ethylene glycol structure (—CH ₂ CH ₂ O—) with high lithium ion conductivity, the surface of the negative electrode active material A vinyl ether compound having a phenyl group with high affinity and a fluorine-containing vinyl ether compound having high resistance to an electrolytic solution are preferable. Moreover, a bifunctional vinyl ether compound is preferable in that the film effect on the negative electrode surface is large.

  In the present embodiment, the preferred vinyl ether compound is not particularly limited as long as it can be dispersed in the dispersion medium of the negative electrode slurry, and preferably dispersed uniformly. For example, water is used as the dispersion medium of the negative electrode slurry. In this case, ethylene glycol monovinyl ether, diethylene glycol monovinyl ether, 2-hydroxyethyl vinyl ether and 4-hydroxybutyl vinyl ether which are water-soluble vinyl ether compounds are more preferable. When an organic solvent such as NMP is used as a dispersion medium, tetraethylene glycol methyl vinyl ether, 2,2,2-trifluoroethyl vinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, bis [4- (vinyloxy) Butyl] isophthalate is more preferred.

  In this embodiment, the vinyl ether compound is presumed to form a polymer film by cationic polymerization using an acid in the electrolyte as an initiator. The negative electrode prepared by adding a vinyl ether compound to the negative electrode slurry is polymerized on the negative electrode surface (more specifically, the negative electrode active material and the binder surface) by rapid polymerization of the vinyl ether compound in the negative electrode by contact with the electrolyte. Therefore, the decomposition reaction of the electrolytic solution can be suppressed, and a battery having excellent cycle characteristics can be obtained by using this negative electrode. It is preferable that the vinyl ether compound acting as a film-forming additive is dispersed in the negative electrode slurry, and after the negative electrode slurry is applied to the current collector and dried, the vinyl ether compound uniformly adheres to the negative electrode surface.

  Also, if there are too many film-forming additives, the film formed on the negative electrode becomes thicker and the internal resistance of the electrode increases, so the lithium ion conductivity and the electron conductivity in the electrode decrease, and the battery characteristics are reduced. May fall. Therefore, the amount of the vinyl ether compound additive in this embodiment is preferably 0.01 to 5.0% by mass, more preferably 0.10 to 3.0% by mass, and more preferably 0% with respect to the amount of the negative electrode active material. .17-3.0 mass% is preferable. The lower the amount added, the more advantageous in terms of cost.

  In the present specification, when the negative electrode is described as “including” the vinyl ether compound, the vinyl ether compound is dispersed in the negative electrode active material layer, the vinyl ether compound is attached to the negative electrode surface, or the It may represent any state such that at least a part of the vinyl ether compound is polymerized to form a film on the negative electrode surface, and it is understood depending on the context.

-Current collector for negative electrode As a material of the current collector for negative electrode, a known material can be arbitrarily used. For example, a metal material such as copper, nickel, SUS or the like is used. Among these, copper is particularly preferable from the viewpoint of ease of processing and cost. The current collector is preferably subjected to a roughening treatment in advance. Furthermore, the shape of the current collector is also arbitrary, and examples thereof include a foil shape, a flat plate shape, and a mesh shape. Also, a perforated current collector such as expanded metal or punching metal can be used. Moreover, the preferable thickness and shape when using a thin film as the current collector are also arbitrary.

-Method for producing negative electrode As a method for producing the negative electrode, for example, on the negative electrode current collector, a negative electrode active material, a binder for negative electrode, a film-forming additive, and, if necessary, a thickener for negative electrode, a surfactant It can be manufactured by forming a negative electrode active material layer containing the above. Examples of the method for forming the negative electrode active material layer include a doctor blade method, a die coater method, a CVD method, and a sputtering method. After forming a negative electrode active material layer in advance, a thin film of aluminum, nickel, or an alloy thereof may be formed by a method such as vapor deposition or sputtering to form a negative electrode current collector. Among them, a negative electrode active material, a negative electrode binder, a film forming additive, a negative electrode thickener, a surfactant and the like are mixed with a dispersion solvent to prepare a slurry, which is applied onto a current collector, and then dried by heating. This method is preferable because it can be manufactured at low cost. In order to prevent adhesion of the film forming additive to the binder, the negative electrode active material, the negative electrode thickener, the film forming additive, and the surfactant are dispersed, and then the negative electrode binder is added last. Is preferred. The heating and drying temperature after applying the slurry to the negative electrode current collector is preferably 50 ° C. or higher and 140 ° C. or lower, more preferably 80 ° C. or higher and 120 ° C. or lower. As a dispersion solvent, NMP or water is preferable. In this embodiment, it is preferable that the vinyl ether compound mainly adheres to the surface of the negative electrode active material, and more preferable to adhere only to the surface of the negative electrode active material.

  According to this embodiment, at the time of manufacturing for a lithium ion secondary battery, a vinyl ether compound, which is a film forming additive, is added to the negative electrode slurry, and this slurry is applied to the current collector and dried to obtain a film forming addition in advance. A negative electrode containing an agent can be obtained. In this embodiment, the vinyl ether compound is not added to the non-aqueous electrolyte, and the film formed on the negative electrode surface is a polymer of the vinyl ether compound, so that it does not dissolve into the non-aqueous electrolyte. Thereby, since the viscosity of electrolyte solution does not rise, ionic conductivity does not fall. Further, according to the present embodiment, there are advantages such that the film forming additive can be used even if it is incompatible with the electrolytic solution, and since the film forming additive does not adhere to the positive electrode, the resistance of the positive electrode is not increased. . Further, by adding the vinyl ether compound of the present invention in an appropriate addition amount, a uniform negative electrode can be produced without inhibiting the dispersion state of the slurry. Furthermore, since a large amount of additive does not adhere to the binder, the binding effect of the binder is not weakened, and the adhesion between the negative electrode and the current collector does not decrease. Therefore, battery characteristics such as battery cycle deterioration and swelling due to internal gas generation can be suppressed, and electrolyte storage characteristics can also be suppressed. Charge / discharge cycle life, especially charge / discharge cycle life at high temperatures and capacity retention It is possible to provide an excellent non-aqueous electrolyte secondary battery that is excellent in characteristics and improved in resistance increase (particularly resistance increase after storage).

[2] Positive electrode / positive electrode active material layer The positive electrode active material layer is prepared by, for example, preparing a slurry containing a positive electrode active material, a binder, and a solvent (and further a conductive aid if necessary), and applying this onto a positive electrode current collector. Then, it can be produced by forming a positive electrode active material layer on the positive electrode current collector by drying and pressurizing as necessary.

Although it does not restrict | limit especially as a positive electrode active material, For example, lithium complex oxide, lithium iron phosphate, etc. can be used. Examples of the lithium composite oxide include lithium manganate (LiMn ₂ O ₄ ); lithium cobaltate (LiCoO ₂ ); lithium nickelate (LiNiO ₂ ); and at least part of the manganese, cobalt, and nickel portions of these lithium compounds. Substituted with other metal elements such as aluminum, magnesium, titanium, zinc, zirconium; nickel-substituted lithium manganate in which a part of manganese in lithium manganate is substituted with at least nickel; a part of nickel in lithium nickelate is at least cobalt Cobalt-substituted lithium nickelate substituted with nickel; a part of manganese of nickel-substituted lithium manganate substituted with another metal (for example, at least one of aluminum, magnesium, titanium, and zinc); cobalt-substituted lithium nickelate Some of the nickel other metallic elements (e.g. aluminum, magnesium, titanium, at least one zinc) include those substituted with. Furthermore, the following formula (A):
^{_{Li x M 1 y M 2 z}} -s Fe s O 2-δ (A)
(Wherein x, y, z, s and δ are 1.16 ≦ x ≦ 1.32, 0.33 ≦ y ≦ 0.63, 0.06 ≦ z ≦ 0.50, 0.06 ≦ s. ≦ 0.50, z ≧ s, 0 ≦ δ ≦ 0.80, M ¹ is at least one metal element selected from Mn, Ti, and Zr and contains Mn, and M ² is Co, Ni, Mn A lithium iron manganese-based composite oxide having a layered rock salt structure, which is at least one metal element selected from These lithium composite oxides may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  Regarding the average particle diameter of the positive electrode active material, for example, a positive electrode active material having an average particle diameter in the range of 0.1 to 50 μm can be used from the viewpoint of reactivity with the electrolytic solution, rate characteristics, and the like. A positive electrode active material having a particle diameter in the range of 1 to 30 μm, more preferably an average particle diameter in the range of 5 to 25 μm can be used. Here, the average particle diameter means a particle diameter (median diameter: D50) at an integrated value of 50% in a particle size distribution (volume basis) by a laser diffraction scattering method.

  As the positive electrode binder that binds and integrates the positive electrode active material, specifically, the same negative electrode binder as that described above can be used. As the positive electrode binder, polyvinylidene fluoride is preferable from the viewpoint of versatility and low cost. The amount of the positive electrode binder used is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. When the content of the positive electrode binder is 2 parts by mass or more, the adhesion between the active materials or between the active material and the current collector is improved, and the cycle characteristics are improved. The substance ratio is improved and the positive electrode capacity can be improved.

  A conductive auxiliary material may be added to the positive electrode active material layer for the purpose of reducing the impedance of the positive electrode active material. As the conductive auxiliary material, carbonaceous fine particles such as graphite, carbon black, and acetylene black can be used.

・ Binder for positive electrode The binder for positive electrode is not particularly limited. For example, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer. Styrene-butadiene copolymer rubber, polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamideimide and the like can be used. Among these, polyimide, polyamideimide, polyacrylic acid (including lithium salt, sodium salt and potassium salt neutralized with alkali), carboxymethylcellulose (lithium salt neutralized with alkali) due to its strong binding properties , Sodium salts and potassium salts) are preferred. The amount of the binder for the positive electrode to be used is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material from the viewpoints of “sufficient binding force” and “high energy” which are in a trade-off relationship. .

-Current collector for positive electrode The current collector for positive electrode should support the positive electrode active material layer including the positive electrode active material integrated by the binder and have conductivity that enables conduction with the external terminal. Specifically, the same negative electrode current collector as described above can be used.

・ Method for producing positive electrode There is no particular limitation on the method for producing the positive electrode. For example, lithium manganese composite oxide such as lithium manganate or lithium iron manganese composite oxide having a layered rock salt structure is electrically conductive. After mixing with an auxiliary material and a binder together with a suitable dispersion medium that can dissolve the binder (slurry method), the mixture is applied onto a current collector such as an aluminum foil, the solvent is dried, and then pressed. Compress to form a film. In addition, there is no restriction | limiting in particular as a conductive support material, Usually used things, such as carbon black, acetylene black, natural graphite, artificial graphite, carbon fiber, can be used.

[3] Electrolyte solution The electrolyte solution includes, as an aprotic solvent, cyclic carbonates, chain carbonates, aliphatic carboxylic acid esters, γ-lactones, cyclic ethers, chain ethers and fluorine derivatives thereof, One or more solvents selected from the group consisting of can be included. Specifically, for example, cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dipropyl Linear carbonates such as carbonate (DPC), aliphatic carboxylic acid esters such as methyl formate, methyl acetate and ethyl propionate, γ-lactones such as γ-butyrolactone, 1,2-diethoxyethane (DEE), Chain ethers such as ethoxymethoxyethane (EME), cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, acetamide, dimethylformamide, acetonitrile, Proponitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, 1,3-dimethyl-2-imidazolidinone, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, N- Among methylpyrrolidone and the like, one kind or a mixture of two or more kinds can be used.

The electrolyte solution for a secondary battery according to the present embodiment may further include a lithium salt as an electrolyte. In this way, since lithium ions can be used as a mobile substance, battery characteristics can be improved. Examples of lithium salts include lithium imide salt, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , LiAlCl ₄ , LiN (C _n F _{2n + 1} SO ₂ ) (C _m F _{2m + 1} SO ₂ ) (n and m are natural numbers) It can be set as the structure containing one or more substances selected from these. In particular, it is preferable to use LiPF ₆ or LiBF ₄ . By using these, the electrical conductivity of the lithium salt can be increased, and the cycle characteristics of the secondary battery can be further improved.

The acid generated by the slight decomposition of the lithium salt in the electrolytic solution causes the polymerization reaction of the vinyl ether compound in the negative electrode to rapidly occur on the negative electrode surface to form a polymer film. Therefore, for film formation, it is preferable to charge / discharge after contact between the electrolyte solution and the electrode, for example, after 10 minutes to 1 day. If necessary, a polymerization initiator may be added to the electrolytic solution. The contact between the electrolytic solution and the electrode may be performed by impregnating the electrode with an electrolytic solution or a solution containing a polymerization initiator before the assembly of the cell, or after the assembly of the cell, the electrolytic solution is injected into the cell. It may be done by doing. The reaction time varies depending on the type and concentration of the vinyl ether compound, the type and concentration of the lithium salt or polymerization initiator, the reaction temperature, and the like. LiPF ₆ or LiBF ₄ is preferably used as the lithium salt that easily generates an acid.

  When a vinyl ether compound is added to the electrolytic solution, a polymerization reaction occurs and the electrolytic solution becomes a gel. Therefore, it is not preferable to add a vinyl ether compound to the electrolytic solution.

  As the polymerization initiator, known initiators such as Bronsted acids and Lewis acids can be used. Examples of Bronsted acids include hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, trichloroacetic acid, and trifluoroacetic acid. Examples of Lewis acids include boron trifluoride, aluminum trichloride, aluminum tribromide, tin tetrachloride, zinc dichloride, and ferric chloride. The solution is not particularly limited as long as it is inert to the polymerization reaction. For example, hydrocarbon solvents such as hexane, benzene and toluene, and ether solvents such as ethyl ether, 1,2-dimethoxyethane and tetrahydrofuran are preferable.

  In addition to the cyclic sulfonic acid ester having at least two sulfonyl groups, the electrolytic solution may further include a compound having one or more sulfonyl groups. Moreover, it can also be set as the structure which further contains vinylene carbonate, vinyl ethylene carbonate, divinyl ethylene carbonate, fluoroethylene carbonate, etc.

[4] Separator The separator is not particularly limited, and a porous film such as polypropylene or polyethylene or a nonwoven fabric can be used. Moreover, what laminated | stacked them can also be used as a separator.

[5] Exterior Body The exterior body is not particularly limited, and for example, a laminate film can be used. The laminate film can be appropriately selected as long as it is stable to the electrolytic solution and has a sufficient water vapor barrier property. As the laminate film, for example, a laminate film made of polypropylene, polyethylene or the like coated with aluminum, silica, or alumina can be used as the outer package. In particular, an aluminum laminate film is preferable from the viewpoint of suppressing volume expansion.

  In the case of a secondary battery using a laminate film as an exterior body, the distortion of the electrode element is greatly increased when gas is generated, compared to a secondary battery using a metal can as the exterior body. This is because the laminate film is more easily deformed by the internal pressure of the secondary battery than the metal can. Furthermore, when sealing a secondary battery using a laminate film as an exterior body, the internal pressure of the battery is usually lower than the atmospheric pressure, so there is no extra space inside, and if gas is generated, it is immediately It may lead to battery volume changes and electrode element deformation.

  The secondary battery according to the present embodiment can overcome the above problem. As a result, it is possible to provide a laminate-type lithium ion secondary battery that is inexpensive and has excellent flexibility in designing the cell capacity by changing the number of layers. A typical layer configuration of the laminate film includes a configuration in which a metal thin film layer and a heat-fusible resin layer are laminated. In addition, as a typical layer structure of a laminate film, a protective layer made of a film of polyester such as polyethylene terephthalate or nylon is further laminated on the surface of the metal thin film layer opposite to the heat fusion resin layer. The structure which was made is mentioned. When sealing the battery element, the battery element is surrounded with the heat-fusible resin layer facing each other. As the metal thin film layer, for example, a foil of Al, Ti, Ti alloy, Fe, stainless steel, Mg alloy or the like having a thickness of 10 to 100 μm is used. The resin used for the heat-fusible resin layer is not particularly limited as long as it can be heat-sealed. For example, polypropylene, polyethylene, these acid modified products, polyphenylene sulfide, polyesters such as polyethylene terephthalate, polyamide, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer and ethylene-acrylic acid copolymer with metal ions. An ionomer resin bonded between molecules is used as the heat-fusible resin layer. The thickness of the heat-fusible resin layer is preferably 10 to 200 μm, more preferably 30 to 100 μm.

[6] Battery configuration The configuration of the secondary battery is not particularly limited. For example, a laminated laminate type in which an electrode element in which a positive electrode and a negative electrode are arranged to face each other and an electrolyte is included in an outer package. It can be. FIG. 1 is a schematic cross-sectional view showing a structure of an electrode element included in a laminated laminate type secondary battery. This electrode element is formed by alternately stacking a plurality of positive electrodes 1 and a plurality of negative electrodes 3 having a planar structure with a separator 2 interposed therebetween. The positive electrode current collector 1b of each positive electrode 1 is welded and electrically connected to each other at an end portion not covered with the positive electrode active material layer 1a, and the positive electrode terminal 4 is welded to the welded portion. The negative electrode current collector 3b included in each negative electrode 3 is welded and electrically connected to each other at an end portion not covered with the negative electrode active material layer 3a, and the negative electrode terminal 6 is welded to the welded portion. Further, the positive electrode terminal 4 is welded to the positive electrode tab 5, and the negative electrode terminal 6 is welded to the negative electrode tab 7. Since the electrode element having such a planar laminated structure does not have a portion with a small R (a region close to the winding core of the wound structure), the electrode element associated with charge / discharge is compared with an electrode element having a wound structure. There is an advantage that it is difficult to be adversely affected by volume changes. That is, it is effective as an electrode element using an active material that easily causes volume expansion. On the other hand, in an electrode element having a wound structure, since the electrode is curved, the structure is easily distorted when a volume change occurs. In particular, when a negative electrode active material having a large volume change due to charge / discharge, such as silicon oxide, is used, a secondary battery using an electrode element having a wound structure has a large capacity reduction due to charge / discharge.

  However, the electrode element having a planar laminated structure has a problem that when the gas is generated between the electrodes, the generated gas tends to stay between the electrodes. This is because, in the case of an electrode element having a wound structure, the distance between the electrodes is difficult to widen because tension is applied to the electrodes, whereas in the case of an electrode element having a laminated structure, the distance between the electrodes is widened. This is because it is easy. This problem is particularly noticeable when the outer package is an aluminum laminate film.

  In the present invention, the above problem can be solved by including a vinyl ether compound in the negative electrode, and a long-life driving is possible even in a laminated laminate type lithium ion secondary battery using a high energy negative electrode. Become. Therefore, a secondary battery according to an embodiment of the present invention includes a laminated laminate type battery having an electrode element in which a positive electrode and a negative electrode are arranged to face each other, an electrolytic solution, and an outer package containing the electrode element and the electrolytic solution. The negative electrode includes a negative electrode active material including at least one of a carbon material, a metal that can be alloyed with lithium, and a metal oxide that can occlude and release lithium ions, and includes a negative electrode binder. A negative electrode current collector is bound, and the negative electrode contains a vinyl ether compound. This is also effective in a secondary battery using an electrode element having a wound structure.

[Other Embodiments of the Invention]
In the above-described embodiment, a compound generally known as a positive electrode active material such as LiCoO ₂ can be mixed and used in a positive electrode active material mainly including a surface-treated Mn-based positive electrode. Further, for safety and the like, a commonly used additive substance such as Li ₂ CO ₃ can be further added.

  Moreover, in the said embodiment, various shapes, such as a square shape, a paper type, a lamination | stacking type | mold, a cylindrical shape, and a coin type | mold, can be employ | adopted as an exterior body of a battery. The exterior material and other constituent members are not particularly limited, and may be selected according to the battery shape. For example, a film-like outer package is a film obtained by laminating the above-mentioned heat-fusible resin film directly or via an adhesive on a heat-resistant resin film such as polyethylene terephthalate, or a heat-fusible resin film alone film, etc. Can be configured.

  The lithium ion secondary battery described in this specification can be combined with a plurality of batteries to form a battery pack. Further, the lithium ion secondary battery or its assembled battery described in this specification is optimal as a power source for driving a motor, and can be used in a vehicle application or the like.

  Examples of the present invention will be specifically described below, but the present invention is not limited thereto.

(Example 1)
[Production of negative electrode]
The negative electrode sheet is 20 g of carbon (graphite), 0.86 g of carbon powder (acetylene black) as a conductive substance, 22 g of a 1.0 mass% carboxymethylcellulose (CMC) aqueous solution, and ethylene represented by the following formula as a film forming additive. 0.036 g of glycol monovinyl ether (hereinafter also referred to as “Compound 1”) (0.18% by mass with respect to carbon) was mixed. To this mixture, 1.1 g of 40 mass% SBR aqueous solution was added and stirred to prepare a uniform slurry. This slurry was applied to the surface of a copper foil having a thickness of 10 μm so as to have an amount of 16 mg per 1 cm ² , dried at 80 ° C. for 20 minutes, and further pressed to prepare a negative electrode sheet having a thickness of 150 μm.

[Production of coin cell]
The obtained negative electrode sheet was punched into a circular shape having a diameter of 12 mm, and immersed in an electrolytic solution, so that the electrolytic solution was infiltrated into voids in the electrode. As the electrolytic solution, an ethylene carbonate / diethyl carbonate mixed solution (mixing ratio 3: 7) containing 1.0 mol / L LiPF ₆ electrolyte salt was used. A polypropylene porous film separator impregnated with the electrolytic solution was laminated on the electrode impregnated with the electrolytic solution. Further, a lithium metal disk was laminated as a counter electrode, and this was put into a stainless steel coin-type battery outer package, and pressure was applied by a caulking machine to obtain a sealed coin-type cell.

[Cell characteristics evaluation]
30 minutes after the negative electrode sheet was impregnated with the electrolyte, the initial storage capacity was defined as the initial storage capacity when lithium ions were stored in the negative electrode at 20 ° C. with a constant current of 0.25 mA up to the lower limit voltage of 0V. In addition, the above-described charging cell was discharged at a constant current of 0.25 mA to an upper limit voltage of 2 V, and then recharged to a lower limit voltage of 0 V at a constant current of 0.5 mA. Plot the current value and the voltage value after 10 seconds when a constant current (0.5 mA, 1 mA, 1.5 mA, 2 mA, 2.5 mA) is applied to this recharged cell for 10 seconds, and the slope is negative. The initial resistance value (internal resistance value) was calculated. Thereafter, 20 cycles of charge and discharge were performed at 20 ° C. with a constant current voltage.

(Example 2)
Evaluation similar to Example 1 was performed except that 0.10 g (0.52% by mass with respect to carbon) of Compound 1 was mixed as a film forming additive to prepare a negative electrode.

(Example 3)
Evaluation was performed in the same manner as in Example 1 except that 0.32 g (1.6% by mass with respect to carbon) of Compound 1 was mixed as a film forming additive to prepare a negative electrode.

Example 4
As a film-forming additive, 0.042 g (0.21% by mass with respect to carbon) of diethylene glycol monovinyl ether represented by the following formula (hereinafter also referred to as “compound 2”) was mixed to prepare a negative electrode. The same evaluation as in Example 1 was performed.

(Example 5)
Evaluation was performed in the same manner as in Example 1 except that 0.11 g (0.56% by mass with respect to carbon) of Compound 2 was mixed as a film forming additive to prepare a negative electrode.

(Example 6)
Evaluation was performed in the same manner as in Example 1 except that 0.28 g (1.4% by mass based on carbon) of Compound 2 was mixed as a film forming additive to prepare a negative electrode.

(Example 7)
As a film-forming additive, 0.038 g (0.19% by mass with respect to carbon) of 4-hydroxybutyl vinyl ether (hereinafter also referred to as “compound 3”) represented by the following formula was mixed to prepare a negative electrode. Except for this, the same evaluation as in Example 1 was performed.

(Example 8)
Evaluation was performed in the same manner as in Example 1 except that 0.11 g (0.54% by mass based on carbon) of Compound 3 was mixed as a film forming additive to prepare a negative electrode.

Example 9
Evaluation was performed in the same manner as in Example 1 except that 0.36 g of compound 3 (1.8% by mass with respect to carbon) was mixed as a film forming additive to prepare a negative electrode.

(Example 10)
The negative electrode sheet is 20 g of carbon (graphite), 0.86 g of carbon powder (acetylene black) as a conductive material, 1.0 g of PVdF, N-methylpyrrolidone, and tetraethylene glycol methyl vinyl ether represented by the following formula as a film forming additive. 0.034 g (hereinafter also referred to as “compound 4”) (0.17% by mass with respect to carbon) was added and stirred to prepare a uniform slurry. This slurry was applied to the surface of a copper foil having a thickness of 10 μm so as to have an amount of 16 mg per 1 cm ² , dried at 100 ° C. for 20 minutes, and further pressed to prepare a negative electrode sheet having a thickness of 150 μm. Evaluation similar to Example 1 was performed except producing the negative electrode.

(Example 11)
The same evaluation as in Example 10 was performed except that 0.10 g (0.49% by mass with respect to Compound 4) of Compound 4 was mixed as a film forming additive to prepare a negative electrode.

(Example 12)
Evaluation was performed in the same manner as in Example 10 except that 0.36 g of compound 4 (1.8% by mass with respect to carbon) was mixed as a film forming additive to prepare a negative electrode.

(Example 13)
As a film forming additive, 0.040 g (0.20% by mass with respect to carbon) of 2,2,2-trifluoroethyl vinyl ether (hereinafter also referred to as “compound 5”) represented by the following formula was mixed. The same evaluation as in Example 10 was performed except that a negative electrode was produced.

(Example 14)
Evaluation was performed in the same manner as in Example 10 except that 0.11 g (0.54% by mass with respect to carbon) of Compound 5 was mixed as a film forming additive to prepare a negative electrode.

(Example 15)
Evaluation was performed in the same manner as in Example 10 except that 0.46 g (2.3 mass% with respect to carbon) of Compound 5 was mixed as a film forming additive to prepare a negative electrode.

(Example 16)
As a film forming additive, 0.042 g (0.21% by mass with respect to carbon) of diethylene glycol divinyl ether (hereinafter also referred to as “compound 6”) represented by the following formula was mixed to prepare a negative electrode. The same evaluation as in Example 10 was performed.

(Example 17)
Evaluation similar to Example 10 was performed except that 0.11 g (0.57% by mass with respect to carbon) of compound 6 was mixed as a film forming additive to prepare a negative electrode.

(Example 18)
Evaluation was performed in the same manner as in Example 10 except that 0.38 g (1.9% by mass with respect to carbon) of Compound 6 was mixed as a film forming additive to prepare a negative electrode.

(Example 19)
As a film forming additive, 0.038 g (0.19% by mass with respect to carbon) of triethylene glycol divinyl ether (hereinafter also referred to as “compound 7”) represented by the following formula was mixed to prepare a negative electrode. Except for this, the same evaluation as in Example 10 was performed.

(Example 20)
Evaluation was performed in the same manner as in Example 10 except that 0.11 g (0.54% by mass based on carbon) of Compound 7 was mixed as a film forming additive to prepare a negative electrode.

(Example 21)
Evaluation was performed in the same manner as in Example 10 except that 0.50 g (2.5% by mass based on carbon) of Compound 7 was mixed as a film forming additive to prepare a negative electrode.

(Example 22)
As a film forming additive, 0.038 g (0.19% by mass with respect to carbon) of bis [4- (vinyloxy) butyl] isophthalate (hereinafter also referred to as “compound 8”) represented by the following formula was mixed. Then, the same evaluation as in Example 10 was performed except that the negative electrode was produced.

(Example 23)
The same evaluation as in Example 10 was performed except that 0.19 g (0.95% by mass with respect to carbon) of Compound 8 was mixed as a film forming additive to prepare a negative electrode.

(Example 24)
Evaluation was performed in the same manner as in Example 10 except that 0.60 g (3.0% by mass based on carbon) of Compound 8 was mixed as a film forming additive to prepare a negative electrode.

(Comparative Example 1)
The same evaluation as in Example 1 was performed except that the negative electrode was produced without adding the film forming additive.

(Reference Example 1)
The same evaluation as in Example 1 was performed except that Compound 1 was used as a film-forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

(Reference Example 2)
The same evaluation as in Example 1 was performed, except that Compound 2 was used as a film forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

(Reference Example 3)
The same evaluation as in Example 1 was performed, except that Compound 3 was used as a film forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

(Reference Example 4)
The same evaluation as in Example 10 was performed except that Compound 4 was used as a film forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

(Reference Example 5)
The same evaluation as in Example 10 was performed, except that Compound 5 was used as a film forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

(Reference Example 6)
The same evaluation as in Example 10 was performed except that Compound 6 was used as a film forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

(Reference Example 7)
The same evaluation as in Example 10 was performed except that Compound 7 was used as a film forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

(Reference Example 8)
The same evaluation as in Example 10 was performed except that Compound 8 was used as a film forming additive and the amount added was changed to 1.1 g (5.5% by mass with respect to carbon) to produce a negative electrode.

  The evaluation results are shown in Table 1. Table 1 evaluates the initial charge capacity, internal resistance value, and cycle characteristics when an additive is added to the negative electrode slurry. In Examples 1 to 24 in which the vinyl ether compound was added in the range of 0.17% to 3.0%, the internal resistance value was almost the same as the resistance value without the additive (Comparative Example 1). In Reference Examples 1 to 8 in which 5% was added, the resistance value increased significantly. This is presumably because a polymer film was formed by the polymerization reaction of the vinyl ether compound on the negative electrode surface. In Examples 1 to 24, a good film was formed on the surface of the negative electrode, whereas in Reference Examples 1 to 8, the amount of the vinyl ether compound added was larger than that of the example, so that the film was thickened. It is thought that it was greatly increased. Then, after 20 cycles of the charge / discharge test, the cycle characteristics were good in Examples 1 to 24, whereas in Comparative Example 1 and Reference Examples 1 to 8, the cycle characteristics were poor. In Examples 1 to 24, it was considered that good cycle characteristics were exhibited as a result of the electrolyte solution decomposition reaction on the negative electrode surface being suppressed by a good film. On the other hand, in Comparative Example 1 having no additive, since a good film is not formed on the negative electrode surface, the electrolytic solution decomposition reaction proceeds on the negative electrode surface due to repeated charge and discharge, and the decomposition product accumulates on the negative electrode surface. It seems that resistance increased and cycle characteristics decreased. Moreover, in Reference Examples 1-8, it was not able to charge. This is presumably because the lithium ion conductivity was greatly reduced as a result of increasing the film thickness because the amount of vinyl ether compound added was larger than in the Examples.

  The main invention of the present invention is as described in the claims, and further, the following matters are also disclosed.

(Appendix 1)
A negative electrode for a secondary battery comprising at least one selected from the group consisting of vinyl ether compounds represented by formula (1) or formula (2).

（式（１）中、Ｒ_１は、−Ｃ_ａＨ_２ａＯＨ（ａは１〜１０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｂＨ（ｂは２〜１０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｃ−Ｃ_ｄＨ_２ｄ＋１（ｃは１〜１０の整数、ｄは１〜５の整数）、シクロヘキシル基、フェニル基または−Ｃ_ｅＨ_２ｅ＋１（ｅは１〜２０の整数、ただし、−Ｃ_ｅＨ_２ｅ＋１の水素原子の少なくとも一部がフッ素原子で置換されていてもよく、また、−Ｃ_ｅＨ_２ｅ＋１は直鎖であっても分岐鎖であってもよい）である。）

(In the formula (1), _{R 1 is,} -C _a H 2a OH (a is an integer of from 1 to _{10), - (CH 2 CH 2} O) b H (b is 2-10 integer), - (CH _{2 CH 2 O) c -C d} H 2d + 1 (c is an integer of from 1 to 10, d is an integer of from 1 to 5), a cyclohexyl group, a phenyl group or _-C e _{H 2e +} 1 (e is an integer of 1 to 20, provided that , -C _e H _{2e + 1} may be substituted with a fluorine atom, and -C _e H _{2e + 1} may be linear or branched).

（式（２）中、Ｒ_２は、−Ｃ_ｆＨ_２ｆ−（ｆは１〜２０の整数）、−（ＣＨ_２ＣＨ_２Ｏ）_ｇ−ＣＨ_２ＣＨ_２−（ｇは１〜１０の整数）、−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−、−Ｃ_ｈＨ_２ｈ−Ｏ−ＣＯ−Ｃ_６Ｈ_４−ＣＯ−Ｏ−Ｃ_ｉＨ_２ｉ−（ｈおよびｉはそれぞれ独立に１〜１０の整数）、−Ｃ_ｊＨ_２ｊ−Ｏ−ＣＯ−ＮＨ−Ｃ_ｋＨ_２ｋ−ＮＨ−ＣＯ−Ｏ−Ｃ_ｌＨ_２ｌ−（ｊ、ｋおよびｌはそれぞれ独立に１〜１０の整数）、−Ｃ_ｍＨ_２ｍ−Ｏ−ＣＯ−Ｃ_ｎＨ_２ｎ−ＣＯ−Ｏ−Ｃ_ｐＨ_２ｐ−（ｍ、ｎおよびｐはそれぞれ独立に１〜１０の整数）、−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−Ｏ−ＣＯ−Ｃ_ｑＨ_２ｑ−ＣＯ−Ｏ−ＣＨ_２−Ｃ_６Ｈ_１０−ＣＨ_２−（ｑは１〜１０の整数）または−Ｃ_ｒＨ_２ｒ−Ｏ−ＣＯ−Ｏ−Ｃ_ｓＨ_２ｓ−（ｒおよびｓはそれぞれ独立に１〜１０の整数）である。）

(In the formula (2), _{R 2 is,} -C _{f H 2f} - _(f is an integer of 1 to _{20), - (CH 2 CH 2} O) g -CH 2 CH 2 - (g is an integer of from 1 to 10 _{), - CH 2 -C 6 H} 10 -CH 2 -, - C h H 2h -O-CO-C 6 H 4 -CO-O-C i H 2i - (1~10 h and i are each independently _{integer) of, - C j H 2j -O-} CO-NH-C k H 2k -NH-CO-O-C l H 2l - (j, k and l are each independently an integer of 1 to 10), - _{C m H 2m -O-CO-} C n H 2n -CO-O-C p H 2p - (m, n and p each independently of 1 to 10 _{integer), - CH 2 -C 6 H} 10 -CH _{2 -O-CO-C q H} 2q -CO-O-CH 2 -C 6 H 10 -CH 2 - (q is an integer of from 1 to 10) or _-C r _{H 2 r -O-CO-O-C} s H 2s - (r and s are each independently an integer from 1 to 10) is).

(Appendix 2)
The supplementary note 1, wherein the vinyl ether compound represented by the formula (1) or the formula (2) is contained in a range of 0.01% by mass to 5.0% by mass with respect to the negative electrode active material. Negative electrode.

(Appendix 3)
The vinyl ether compound includes ethylene glycol monovinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, tetraethylene glycol methyl vinyl ether, 2,2,2-trifluoroethyl vinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether and bis [4. The negative electrode according to appendix 1 or 2, wherein the negative electrode is at least one selected from the group consisting of-(vinyloxy) butyl] isophthalate.

(Appendix 4)
The negative electrode according to any one of appendices 1 to 3, wherein the vinyl ether compound is attached to a negative electrode surface.

(Appendix 5)
The negative electrode according to any one of appendices 1 to 3, wherein the vinyl ether compound forms a film on the negative electrode surface.

(Appendix 6)
A secondary battery comprising an electrode element in which the positive electrode and the negative electrode according to appendix 5 are arranged to face each other, and an electrolyte.

(Appendix 7)
Furthermore, the secondary battery of Claim 6 provided with the exterior body which includes the said electrode element and the said electrolyte solution, and the said exterior body is a laminate film.

(Appendix 8)
The secondary battery according to appendix 7, wherein the secondary battery is a laminated laminate type having an electrode element in which the negative electrode and the positive electrode are laminated with a separator interposed therebetween.

(Appendix 9)
An assembled battery using the secondary battery according to any one of appendices 6 to 8.

(Appendix 10)
A vehicle equipped with the secondary battery according to any one of appendices 6 to 8 or the assembled battery according to appendix 9 as a motor driving power source.

(Appendix 11)
An electrical storage facility equipped with the secondary battery according to any one of appendices 6 to 8 or the assembled battery according to appendix 9.

(Appendix 12)
A step of preparing a negative electrode slurry in which at least one selected from the group consisting of vinyl ether compounds represented by formula (1) or formula (2), a negative electrode active material, and a binder are dispersed in a dispersion medium;
Applying the negative electrode slurry to a negative electrode current collector and drying;
A method for producing a negative electrode, comprising:

(Appendix 13)
In the step of preparing the negative electrode slurry,
13. The method for producing a negative electrode according to appendix 12, wherein a negative electrode slurry is prepared by further adding a binder after dispersing the vinyl ether compound and the negative electrode active material in a dispersion medium.

(Appendix 14)
14. The method for producing a negative electrode according to appendix 12 or 13, wherein a negative electrode in which the vinyl ether compound is attached to the surface of the negative electrode active material is obtained.

(Appendix 15)
Including a step of forming a film on the surface of the negative electrode by bringing the negative electrode manufactured by the manufacturing method according to any one of appendices 12 to 14 into contact with an electrolytic solution before enclosing the negative electrode in an exterior body. A method for producing a negative electrode, which is characterized.

(Appendix 16)
A method for producing a secondary battery comprising an electrode element in which a positive electrode and a negative electrode are arranged to face each other, and an electrolyte solution,
A step of opposingly arranging the positive electrode and the negative electrode produced by the production method according to any one of appendices 12 to 14 to produce an electrode element;
Enclosing the electrode element and the electrolytic solution in an exterior body;
And a film is formed on the surface of the negative electrode by impregnating the negative electrode with the electrolytic solution.

  The present embodiment can be used in, for example, all industrial fields that require a power source and industrial fields related to transportation, storage, and supply of electrical energy. Specifically, power supplies for mobile devices such as mobile phones and notebook computers; power supplies for transportation and transportation media such as trains, satellites, and submarines, including electric vehicles such as electric cars, hybrid cars, electric bikes, and electric assist bicycles A backup power source such as a UPS; a power storage facility for storing power generated by solar power generation, wind power generation, etc .;

1a positive electrode active material layer 1b positive electrode current collector 2 separator 3a negative electrode active material layer 3b negative electrode current collector 4 positive electrode terminal 5 positive electrode tab 6 negative electrode terminal 7 negative electrode tab

Claims (10)

A negative electrode for a secondary battery comprising at least one selected from the group consisting of vinyl ether compounds represented by formula (1) or formula (2).

(In the formula (1), _{R 1 is,} -C _a H 2a OH (a is an integer of from 1 to _{10), - (CH 2 CH 2} O) b H (b is 2-10 integer), - (CH _{2 CH 2 O) c -C d} H 2d + 1 (c is an integer of from 1 to 10, d is an integer of from 1 to 5), a cyclohexyl group, a phenyl group or _-C e _{H 2e +} 1 (e is an integer of 1 to 20, provided that , -C _e H _{2e + 1} may be substituted with a fluorine atom, and -C _e H _{2e + 1} may be linear or branched).

(In the formula (2), _{R 2 is,} -C _{f H 2f} - _(f is an integer of 1 to _{20), - (CH 2 CH 2} O) g -CH 2 CH 2 - (g is an integer of from 1 to 10 _{), - CH 2 -C 6 H} 10 -CH 2 -, - C h H 2h -O-CO-C 6 H 4 -CO-O-C i H 2i - (1~10 h and i are each independently _{integer) of, - C j H 2j -O-} CO-NH-C k H 2k -NH-CO-O-C l H 2l - (j, k and l are each independently an integer of 1 to 10), - _{C m H 2m -O-CO-} C n H 2n -CO-O-C p H 2p - (m, n and p each independently of 1 to 10 _{integer), - CH 2 -C 6 H} 10 -CH _{2 -O-CO-C q H} 2q -CO-O-CH 2 -C 6 H 10 -CH 2 - (q is an integer of from 1 to 10) or _-C r _{H 2 r -O-CO-O-C} s H 2s - (r and s are each independently an integer from 1 to 10) is).   The vinyl ether compound represented by the formula (1) or the formula (2) is contained in a range of 0.01% by mass to 5.0% by mass with respect to the negative electrode active material. The negative electrode for secondary batteries as described.   The vinyl ether compound includes ethylene glycol monovinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, tetraethylene glycol methyl vinyl ether, 2,2,2-trifluoroethyl vinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether and bis [4. The negative electrode according to claim 1 or 2, wherein the negative electrode is at least one selected from the group consisting of-(vinyloxy) butyl] isophthalate.   The negative electrode according to any one of claims 1 to 3, wherein the vinyl ether compound is attached to the surface of the negative electrode or forms a film on the surface of the negative electrode.   The secondary battery which has an electrode element by which the positive electrode and the negative electrode as described in any one of Claims 1-4 were opposingly arranged, and electrolyte solution.   An assembled battery using the secondary battery according to claim 5. A step of preparing a negative electrode slurry in which at least one selected from the group consisting of vinyl ether compounds represented by formula (1) or formula (2), a negative electrode active material, and a binder are dispersed in a dispersion medium;
Applying the negative electrode slurry to a negative electrode current collector and drying;
A method for producing a negative electrode, comprising: In the step of preparing the negative electrode slurry,
The method for producing a negative electrode according to claim 7, wherein the vinyl ether compound and the negative electrode active material are dispersed in a dispersion medium, and a binder is further added to prepare a negative electrode slurry.   The method for producing a negative electrode according to claim 7 or 8, wherein a negative electrode in which the vinyl ether compound is attached to the surface of the negative electrode active material is obtained. A method for producing a secondary battery comprising an electrode element in which a positive electrode and a negative electrode are arranged to face each other, and an electrolyte solution,
A step of producing an electrode element by opposingly arranging a positive electrode and a negative electrode produced by the production method according to any one of claims 7 to 9,
Enclosing the electrode element and the electrolytic solution in an exterior body;
And a film is formed on the surface of the negative electrode by impregnating the negative electrode with the electrolytic solution.

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