JP5871183B2 - Lithium ion secondary battery electrode resin composition and lithium ion secondary battery - Google Patents

Description

  The present invention relates to a composition for an electrode of a lithium ion secondary battery that can be suitably used as a power source for equipment that uses electricity as a power source, and particularly for power storage and electric vehicles that require cycle stability. The present invention also relates to a lithium ion secondary battery having an electrode using the composition.

  Lithium ion secondary batteries have been widely used as secondary batteries used as power sources for portable terminals such as notebook personal computers, mobile phones, and PDAs. Lithium ion secondary batteries are also increasingly being used in automobiles, and improvements in charge / discharge cycle characteristics with respect to lithium ion secondary batteries are required.

  A material capable of occluding and releasing lithium ions as an electrode active material carrier, for example, a lithium ion secondary battery using a carbonaceous material as a negative electrode can obtain a high discharge voltage close to that when a metal lithium negative electrode is used. The adhesive force between the carrier and the metal foil is small, peeling occurs during repeated charge / discharge, and the charge / discharge cycle characteristics are not sufficient.

  In order to improve this situation, the structural unit (a) derived from an ethylenically unsaturated carboxylic acid ester monomer and the structural unit (b) derived from an ethylenically unsaturated carboxylic acid monomer have the structural unit (a) / structure. A unit (b) = 99-60 / 1 to 40 (weight ratio), and the total of the structural unit (a) and the structural unit (b) is 80% by weight or more based on the total unit and the active material. A resin composition is disclosed. This polymer (vinyl polymer) uses, for example, 2-ethylhexyl methacrylate, methacrylic acid and divinylbenzene as raw materials, and a non-reactive emulsifier (polyoxyethylene) having a polyoxyethylene chain with respect to 100 parts by mass of these raw materials. It is obtained by polymerizing the raw material by allowing 5 parts of ethylene nonylphenyl ether) (4.3% with respect to 100 parts by mass of the raw material in terms of the mass of the polyoxyalkylene ether chain) to be present in the reaction system. (For example, refer to Patent Document 1).

  In the example described in Patent Document 1, the maintenance rate of the charge capacity is measured to evaluate the cycle characteristics. Here, the maintenance rate of the charge capacity is calculated by dividing the discharge capacity at the time of 50 cycles by the discharge capacity at the time of 3 cycles. Although the evaluation of the cycle characteristics may be performed in an atmosphere at a high temperature of 60 ° C., the charge capacity maintenance rate is about 65 to 73%, which is not sufficient.

  Moreover, the polymer obtained by using the reactive emulsifier (polysynthetic monomer) which has a polyethyleneglycol chain as a part of raw material as a polymer used for the binder composition for lithium ion secondary battery electrodes is disclosed. Specifically, a polymer obtained by using a reactive emulsifier having a polyethylene glycol chain so that the ratio of the mass of the polyethylene glycol chain to the total amount of raw materials is 5 to 15% is disclosed (for example, Patent Documents). 2). According to Example 1 of the patent document, a lithium ion secondary battery obtained using this polymer was measured for electric capacity after charging and discharging at 5 cycles and 50 cycles at a normal charge / discharge rate of 0.1 C. Yes. Under this condition, the ratio of the charge capacity at the end of 50 cycles to the charge capacity at the end of 5 cycles is maintained at about 94%, but if the charge / discharge rate is tightened to 0.2C, it will drop to about 80%. Therefore, the charge / discharge cycle characteristics are not sufficient.

JP 2000-195521 A JP 2001-035496 A

  An object of the present invention is to provide a resin composition for a lithium ion secondary battery electrode from which a lithium ion secondary battery having good cycle characteristics can be obtained, and a lithium ion secondary battery using the composition.

  As a result of intensive studies, the inventors have increased the polyoxyethylene chain content relative to the total mass of the vinyl monomer as compared with Patent Document 1, specifically, an emulsifier so as to be 5 to 15% by mass. The use of a vinyl polymer obtained in the presence of this emulsifier provides a lithium ion secondary battery with excellent cycle characteristics, and this finding is not limited to polyoxyethylene chains. It is only necessary to use an emulsifier so that the above effect is obtained and the mass of the polyoxyethylene chain is 5 to 15% in the reaction system, and the emulsifier has no limitation on reactivity and non-reactivity, and the present invention. It came to complete.

  That is, the present invention relates to a resin for a lithium ion secondary battery electrode containing a vinyl polymer obtained by polymerizing a vinyl monomer in the presence of a non-reactive emulsifier having a polyoxyalkylene ether chain and an active material. It is a composition, and the vinyl polymer is obtained by using the emulsifier so that the ratio of the mass of the polyoxyalkylene ether chain to the total mass of the vinyl monomer is 5 to 15%. A resin composition for a lithium ion secondary battery electrode is provided.

  The present invention also relates to a lithium ion secondary battery electrode containing a vinyl polymer obtained by polymerizing a vinyl monomer in the presence of a non-reactive emulsifier having a polyoxyalkylene ether chain and a carbon-based active material. A composition obtained by using the emulsifier so that the ratio of the mass of the polyoxyalkylene ether chain to the total mass of the vinyl monomer is 5 to 15% by mass. The present invention provides a lithium ion secondary battery having a negative electrode obtained by using the lithium ion secondary battery.

  The lithium ion secondary battery electrode resin composition of the present invention provides a lithium ion secondary battery with good cycle characteristics. Moreover, since it is excellent in adhesiveness with the copper foil which is a raw material of an electrode, and is excellent in flexibility, it is also possible to store the manufactured electrode in a roll shape.

  The vinyl polymer used in the present invention is obtained by polymerizing a vinyl monomer in the presence of a non-reactive emulsifier having a polyoxyalkylene ether chain, and the polyoxyalkylene ether chain with respect to the total mass of the vinyl monomer. It is characterized by being obtained using this emulsifier so that the mass ratio of 5 to 15%. If the mass ratio of the polyoxyalkylene ether chain is less than 5%, the structure of the polyoxyalkylene ether chain effective for transporting lithium ions is small, so that it is difficult to obtain a lithium ion secondary battery with good cycle characteristics. It is not preferable. When the proportion of the mass of the polyoxyalkylene ether chain is more than 15%, the adhesion of the resulting vinyl polymer to the current collector is lowered, and it becomes difficult to obtain a lithium ion secondary battery with good cycle characteristics. It is not preferable. The vinyl polymer used in the vinyl polymer used in the present invention is a polymer obtained by using an emulsifier so that the ratio of the mass of the polyoxyalkylene ether chain to the total mass of the vinyl monomer is 5 to 13%. Is more preferable.

  The mass ratio of the polyoxyalkylene ether chain in the emulsifier used in the present invention can be determined by [(mass of repeating structure portion of polyoxyalkylene ether chain) / total mass of emulsifier].

  Various vinyl monomers can be used as the vinyl monomer that is a raw material of the vinyl polymer, for example, acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Esters: Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate;

Esters of unsaturated carboxylic acids such as maleic acid, fumaric acid and itaconic acid; vinyl esters such as vinyl acetate, vinyl propionate and vinyl tertiary carboxylate; aromatic vinyl monomers such as styrene and vinyltoluene Heterocyclic vinyl monomers such as vinyl pyrrolidone; vinylidene halide compounds such as vinylidene chloride and vinylidene fluoride; α-olefins such as ethylene and propylene; dienes such as butadiene; acrylic acid, methacrylic acid and itacon Carboxyl group-containing vinyl monomers such as acid, maleic acid, fumaric acid, crotonic acid, itaconic acid half ester, maleic acid half ester, maleic anhydride, itaconic anhydride, 2-methacryloylpropionic acid;

Amides of unsaturated carboxylic acids such as acrylamide, methacrylamide and maleic amide; glycidyl group-containing vinyl monomers such as glycidyl methacrylate and allyl glycidyl ether; hydroxyl group-containing vinyl such as 2-hydroxylethyl methacrylate and 2-hydroxylethyl acrylate Monomer; Amino group-containing vinyl monomer such as dimethylaminoethyl methacrylate; Substituted amide of unsaturated carboxylic acid such as N-methylolacrylamide, N-methylolmethacrylamide, diacetoneacrylamide;

Unsaturated bond-containing silane compounds such as γ-methacryloxypropyltrimethoxysilane; two or more unsaturated bonds in one molecule such as diallyl phthalate, divinylbenzene, allyl acrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, etc. Vinyl monomers having; further vinyl chloride, acrylonitrile, vinyl ether, vinyl ketone, vinyl amide;

Acrylic acid polyoxyethylene nonylphenyl ether, Acrylic acid polyoxypropylene lauryl ether, Acrylic acid polyoxypropylene tetradecyl ether, Methacrylic acid polyoxyethylene decyl ether, Methacrylic acid polyoxyethylene cyclohexyl ethyl ether, Methacrylic acid polyoxypropylene stearyl ether And (meth) acrylic acid polyoxyalkylene ether compounds such as polyoxypropylene-2,4-bis (α-methylbenzyl) phenyl ether methacrylate.

  Moreover, following formula (1)

（式中、Ｒ¹およびＲ²は水素、炭素数１〜４の直鎖もしくは分岐のアルキル基、またはハロゲンであり、Ｒ³およびＲ⁴は水素またはメチル基であり［ただし、Ｒ³とＲ⁴が同時にメチル基になることはない］、ｍは３〜２０の整数である。）
で表される単量体もビニル単量体として例示することができる。このようなビニル単量体は、具体的には、例えば、トリエチレングリコールジメタクリレート、テトラエチレングリコールジメタクリレート、ペンタエチレングリコールジメタクリレート、ヘキサエチレングリコールジメタクリレート、ヘプタエチレングリコールジメタクリレート、オクタエチレングリコールジメタクリレート、トリプロピレングリコールジメタクリレート、テトラプロピレングリコールジメタクリレート、ペンタプロピレングリコールジメタクリレート、ヘキサプロピレングリコールジメタクリレート、ヘプタプロピレングリコールジメタクリレート、オクタプロピレングリコールジメタクリレート；これらのメタクリレートの一部をアクリレートに替えた化合物；トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ペンタエチレングリコールジアクリレート、ヘキサエチレングリコールジアクリレート、ヘプタエチレングリコールジアクリレート、オクタエチレングリコールジアクリレート、トリプロピレングリコールジアクリレート、テトラプロピレングリコールジアクリレート、ペンタプロピレングリコールジアクリレート、ヘキサプロピレングリコールジアクリレート、ヘプタプロピレングリコールジアクリレート、オクタプロピレングリコールジアクリレート等が挙げられる。

Wherein R ¹ and R ² are hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, or halogen, and R ³ and R ⁴ are hydrogen or a methyl group [where R ³ and R ⁴ is not a methyl group at the same time], m is an integer of 3 to 20.)
The monomer represented by can also be illustrated as a vinyl monomer. Specific examples of such vinyl monomers include triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, pentaethylene glycol dimethacrylate, hexaethylene glycol dimethacrylate, heptaethylene glycol dimethacrylate, octaethylene glycol dimethacrylate. Methacrylate, tripropylene glycol dimethacrylate, tetrapropylene glycol dimethacrylate, pentapropylene glycol dimethacrylate, hexapropylene glycol dimethacrylate, heptapropylene glycol dimethacrylate, octapropylene glycol dimethacrylate; compounds in which some of these methacrylates are replaced with acrylates ; Triethylene glycol diacrylate, tetraethylene Glycol diacrylate, pentaethylene glycol diacrylate, hexaethylene glycol diacrylate, heptaethylene glycol diacrylate, octaethylene glycol diacrylate, tripropylene glycol diacrylate, tetrapropylene glycol diacrylate, pentapropylene glycol diacrylate, hexapropylene glycol diacrylate Examples include acrylate, heptapropylene glycol diacrylate, and octapropylene glycol diacrylate.

  Moreover, following formula (2)

（式中、Ｒ⁵は水素、炭素数１〜４の直鎖もしくは分岐のアルキル基、またはハロゲンであり、Ｒ⁶は炭素数１〜２０の直鎖、分岐もしくは環状のアルキル基、または炭素数６〜３０のアリール基であり、Ｒ⁷およびＲ⁸は水素またはメチル基であり［ただし、Ｒ⁷とＲ⁸が同時にメチル基になることはない］、ｎは１〜５０の整数である。）
で表される単量体もビニル単量体として例示することができる。このようなビニル単量体は、具体的には、例えば、メトキシポリエチレングリコールメタクリレート、エトキシポリエチレングリコールメタクリレート、メトキシポリエチレングリコールアクリレート、エトキシポリエチレングリコールアクリレート、メトキシジエチレングリコールメタクリレート、エトキシジエチレングリコールアクリレート、メトキシジプロピレングリコールメタクリレート、メトキシジプロピレングリコールアクリレート、メトキシエチルメタクリレート、メトキシエチルアクリレート、２−エトキシエチルメタクリレート、２−エトキシエチルアクリレート、ブトキシエチルメタクリレート、ブトキシエチルアクリレート、フェノキシエチルメタクリレートおよびフェノキシエチルアクリレート等が挙げられる。

(Wherein R ⁵ is hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, or halogen, and R ⁶ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or the number of carbon atoms. 6 to 30 aryl groups, R ⁷ and R ⁸ are hydrogen or a methyl group [provided that R ⁷ and R ⁸ do not simultaneously become a methyl group], and n is an integer of 1 to 50. )
The monomer represented by can also be illustrated as a vinyl monomer. Specific examples of such vinyl monomers include methoxy polyethylene glycol methacrylate, ethoxy polyethylene glycol methacrylate, methoxy polyethylene glycol acrylate, ethoxy polyethylene glycol acrylate, methoxy diethylene glycol methacrylate, ethoxy diethylene glycol acrylate, methoxy dipropylene glycol methacrylate, Examples include methoxydipropylene glycol acrylate, methoxyethyl methacrylate, methoxyethyl acrylate, 2-ethoxyethyl methacrylate, 2-ethoxyethyl acrylate, butoxyethyl methacrylate, butoxyethyl acrylate, phenoxyethyl methacrylate, and phenoxyethyl acrylate.

  Among the vinyl polymers used in the present invention, a vinyl polymer obtained by using butyl acrylate, styrene, and acrylic acid is preferable because an electrode having optimum polarity and heat resistance can be obtained. Among them, butyl acrylate 30 A vinyl polymer obtained by using ~ 90 parts by mass, 10 to 70 parts by mass of styrene, and 1 to 10 parts by mass of acrylic acid is more preferable.

  Examples of the non-reactive emulsifier having a polyoxyalkylene ether chain used in the present invention include an anionic emulsifier having a polyoxyalkylene ether chain, a cationic emulsifier having a polyoxyalkylene ether chain, and a polyoxyalkylene ether chain. Nonionic emulsifiers and the like can be mentioned.

  Examples of the anionic emulsifier having a polyoxyalkylene ether chain include polyoxyalkylene alkyl sulfate salts; polyoxyalkylene alkyl aryl sulfate salts and the like.

  Examples of the cationic emulsifier having a polyoxyalkylene ether chain include polyoxyalkylene ether ammonium chloride.

  Examples of the nonionic emulsifier having a polyoxyalkylene ether chain include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene tridecyl ether. Ethylene alkyl ethers; polyoxyethylene aryl ethers such as polyoxyethylene distyrenated phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene nonyl phenyl ether;

Sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate, sorbitan distearate;

Polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polytetraoleic acid poly Polyoxyethylene sorbitan fatty acid esters such as oxyethylene sorbit; polyoxyethylene sorbitol fatty acid esters;

Glycerin fatty acid esters such as glycerol monostearate, glycerol monooleate, monoglyceride stearin, monoglyceride olein, monoglyceride stearin / olein;

  Examples thereof include polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, and polyethylene glycol monooleate.

  Moreover, the vinyl monomer represented by the said Formula (1) and Formula (2) can also be used as a nonionic emulsifier which has a polyoxyalkylene ether chain.

  Among the emulsifiers having a polyoxyalkylene ether chain used in the present invention, a nonionic emulsifier having a polyoxyalkylene ether chain is obtained because a lithium ion secondary battery having good affinity with lithium ions and improved cycle characteristics is obtained. Among them, polyoxyethylene alkyl ethers and polyoxyethylene aryl ethers are more preferable.

  The number of repeating units of the polyoxyalkylene ether chain in the emulsifier used in the present invention is preferably from 2 to 100, and is preferably from 5 to 50, since a vinyl polymer can be synthesized stably.

  The emulsifier used in the present invention is a non-reactive emulsifier. By using a non-reactive emulsifier, the resulting resin composition for lithium ion secondary battery electrodes can be obtained as a composition that does not impair the mobility of the polyoxyalkylene ether chain, which is believed to contribute to lithium ion transport. The inventors are thinking.

  The vinyl polymer of the present invention is obtained using a non-reactive emulsifier so that the ratio of the mass of the polyoxyalkylene ether chain to the total mass of vinyl monomers is 5 to 15% by mass. Specific examples of the polymerization include, for example, solution polymerization, suspension polymerization, emulsion polymerization, and the like, but since it is a production method that does not include any solvent component and is simple, suspension polymerization, Emulsion polymerization is preferable, and emulsion polymerization is more preferable because an aqueous coating agent having excellent coating film properties can be obtained.

  As an example of emulsion polymerization, with respect to 100 parts by mass of the total amount of vinyl monomers, 0.01 to 10 parts by mass of a radical polymerization initiator and 50 to 10,000 parts by mass of an aqueous medium are used. Polymerization can be performed at 0 to 100 ° C. in the presence. Moreover, it can carry out also in the redox polymerization which uses a radical polymerization initiator and a reducing agent together, and the usage-amount of the reducing agent in this case is 0.01-10 mass parts with respect to 100 mass parts of whole quantity of a vinyl monomer. It is. In this case, a compound that generates a polyvalent metal salt ion such as iron ion or copper ion can be used in combination as an accelerator.

  An example of emulsion polymerization will be described more specifically. First, a pre-emulsion is obtained in which a vinyl monomer and the emulsifier are added to water. The amount of water with respect to 100 parts by mass of the vinyl monomer at this time is not particularly limited, and may be determined in consideration of the performance and amount of the emulsifier. Here, in order to obtain a pre-emulsion in which the vinyl monomer is more satisfactorily dispersed in water, an emulsifier other than the emulsifier having a polyoxyalkylene ether chain may be added as long as the effect of the present invention is not impaired.

  Examples of the emulsifier other than the emulsifier having a polyoxyalkylene ether chain include an anionic emulsifier not having a polyoxyalkylene ether chain, and a cationic emulsifier not having a polyoxyalkylene ether chain.

  Examples of the anionic emulsifier include alkyl sulfates such as sodium dodecyl sulfate, potassium dodecyl sulfate and ammonium dodecyl sulfate; sodium dodecyl polyglycol ether sulfate; sodium sulforicinone; alkali metal salt of sulfonated paraffin; ammonium of sulfonated paraffin Alkyl sulfonates such as salts; sodium laurate, triethanolamine oleate, triethanolamine abiate, sodium laurate, potassium laurate, coconut oil soap, sodium myristate, sodium stearate, sodium palmitate, sodium oleate, olein Fatty acid salts such as potassium acid; sodium benzene sulfonate, alkali phenol High alkylnaphthalenesulfonate; naphthalenesulfonic acid-formalin condensate; mud alkoxyalkyl aryl sulfonates such as alkali metal sulfates of ethylene dialkyl sulfosuccinate salts.

  Examples of the cationic emulsifier include laurylamine hydrochloride, alkylbenzyldimethylammonium chloride, lauryltrimethylammonium chloride, alkylammonium hydroxide, polyoxyethylene alkylamine, and the like.

  Separately from the pre-emulsion, water containing an emulsifier having a polyoxyalkylene ether chain is prepared. The amount of water may be determined in consideration of the nonvolatile content of the target resin emulsion. The amount of the emulsifier may be appropriately adjusted so that the amount of the polyoxyalkylene ether chain in the sum of the emulsifier used in the preparation of the pre-emulsion is 5 to 15% by mass of the mass of the vinyl monomer. .

  After adding the emulsifier, the liquid temperature is raised to, for example, 50 to 90 ° C. And after making a reaction system into nitrogen atmosphere, a part of pre-emulsion is thrown into water. The amount to be charged is usually about 0 to 50% by mass of the total amount of the pre-emulsion. After adding a part of the pre-emulsion, the mixture is stirred for about 5 to 10 minutes.

  After stirring, a polymerization initiator is charged. Examples of the polymerization initiator include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate, azobisisobutyronitrile and its hydrochloride, and 2,2′-azobis (2-amidinopropane) dihydrochloride. Azo initiators such as 4,4′-azobis (4-cyanovaleric acid), peroxide initiators such as hydrogen peroxide, tertiary butyl hydroperoxide, cumene hydroperoxide, and the like.

  Furthermore, known redox initiators using these persulfates or peroxides in combination with reducing agents such as iron ions and sodium sulfooxylate formaldehyde, sodium pyrosulfite, and L-ascorbic acid can also be used.

  When the polymerization initiator is added, it is dissolved after being dissolved in ion exchange water. Here, although the usage-amount of a polymerization initiator is not restrict | limited in particular, For example, it is 0.05-5 mass parts normally with respect to 100 mass parts of vinyl monomers.

  After introducing the polymerization initiator, the mixture is stirred at a liquid temperature of 50 to 90 ° C. for about 5 to 30 minutes. Thereafter, the remaining pre-emulsion and a separately prepared polymerization initiator are further added. When adding, it is dripped normally over 1 to 5 hours. As a usage-amount of a polymerization initiator, it is 0.01-10 mass parts normally with respect to 100 mass parts of vinyl monomers.

  After dripping the whole quantity of a polymerization initiator, it stirs for 1 to 5 hours, and advances polymerization. After completion of the reaction, the reaction solution is cooled, and if necessary, the pH is adjusted with aqueous ammonia and dried to obtain a vinyl polymer used in the present invention.

  The active material used in the present invention includes a negative electrode active material and a positive electrode active material. Negative electrode active materials are mainly classified into carbon-based active materials and non-carbon-based active materials.

  Examples of the carbon-based active material include a carbonaceous material and a graphite material. The carbonaceous material generally indicates a carbon material having a low graphitization degree (low crystallinity) obtained by heat-treating (carbonizing) a carbon precursor at 2000 ° C. or lower. A graphitic material having high crystallinity close to that of graphite obtained by heat-treating at a temperature of 0 ° C. or higher is shown.

  Examples of the carbonaceous material include graphitizable carbon that easily changes the carbon structure depending on the heat treatment temperature, and non-graphitizable carbon having a structure close to an amorphous structure typified by glassy carbon. Examples of graphitizable carbon include carbon materials made from tar pitch obtained from petroleum and coal, such as coke, mesocarbon microbeads (MCMB), mesophase pitch-based carbon fibers, pyrolytic vapor-grown carbon fibers, etc. Is mentioned. MCMB is a carbon fine particle obtained by separating and extracting mesophase spherules produced in the process of heating pitches at around 400 ° C., and mesophase pitch-based carbon fiber is a mesophase pitch obtained by growing and coalescing the mesophase spherules. Is a carbon fiber made from a raw material.

  Examples of the non-graphitizable carbon include phenol resin fired bodies, polyacrylonitrile-based carbon fibers, pseudo-isotropic carbon, and furfuryl alcohol resin fired bodies (PFA).

  Examples of the graphite material include natural graphite and artificial graphite. Artificial graphite is mainly composed of artificial graphite heat-treated at 2800 ° C or higher, graphitized MCMB heat-treated MCMB-based carbon fiber at 2000 ° C or higher, and graphitized mesophase pitch-based carbon fiber heat-treated at 2000 ° C or higher. Etc. are used as the negative electrode active material.

  As the non-carbon-based active material, lithium metal can be used, and simple metals and alloys that form alloys with lithium, oxides and sulfides thereof, and the like are used.

  Examples of single metals and alloys forming lithium alloys include compounds containing metals such as Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, and Zn. Is mentioned. Among these, silicon (Si), tin (Sn) or lead (Pb) simple metals, alloys containing these atoms, or compounds of these metals are used.

  Examples of oxides and sulfides include oxides, carbides, nitrides, silicides, sulfides, and phosphides. Among these, lithium-containing metal composite oxide materials containing a metal element selected from the group consisting of oxides such as tin oxide, manganese oxide, titanium oxide, niobium oxide, vanadium oxide, Si, Sn, Pb and Ti atoms are used. ing.

  As the lithium-containing metal composite oxide, a lithium titanium composite oxide represented by LixTiyMzO4 (0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, 0 ≦ z ≦ 1.6, M is , Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb), among which Li4 / 3Ti5 / 3O4, Li1Ti2O4, Li4 / 5Ti11 / 5O4 are used.

  Among these, an active material having almost no surface functional group is preferable because a high dispersibility improvement effect due to a small particle size of the insoluble component can be obtained. In the active material having almost no surface functional group, the insoluble component of the semi-water-soluble polymer is present between the particles, so that the dispersion of the slurry proceeds due to the osmotic pressure effect. Since the osmotic pressure effect increases as the particle size of the insoluble component decreases, the dispersion of the slurry advances and the stability improves, so that the uniformity of the obtained electrode also improves. As such an active material, a carbon-based active material is preferable.

  As the positive electrode active material, an active material capable of occluding and releasing lithium ions is used, and the positive electrode active material is roughly classified into an inorganic compound and an organic compound. Examples of the positive electrode active material made of an inorganic compound include transition metal oxides, transition metal sulfides, lithium-containing composite metal oxides of lithium and transition metals, and the like. Examples of the transition metal include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Mo.

Transition metal oxides include MnO, MnO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , Cu ₂ V ₂ O ₃ , amorphous V ₂ O—P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O _{13 and the} like can be mentioned. Among them, MnO, V ₂ O ₅ , V ₆ O ₁₃ and TiO ₂ are preferable from the viewpoint of cycle stability and capacity.

The transition metal _sulfide, TiS _2, TiS _3, amorphous _MoS 2, FeS, and the like.

  The structure of the lithium-containing composite metal oxide is not particularly limited, and examples thereof include a layered structure, a spinel structure, and an olivine structure.

As the lithium-containing composite metal oxide having a layered structure, lithium-containing composite oxide mainly composed of lithium-containing cobalt oxide (LiCoO ₂ ), lithium-containing nickel oxide (LiNiO ₂ ), and Co—Ni—Mn composite oxide. Products, lithium-containing composite oxides having a Ni-Mn-Al composite oxide as a main structure, lithium-containing composite oxides having a Ni-Co-Al composite oxide as a main structure, and the like.

Lithium manganate as the lithium-containing composite metal oxide having a spinel structure (LiMn ₂ O ₄₎ and _Li which part was replaced by other transition metals of _{Mn [Mn 3/2 M 1} /2] O 4 ( wherein M may be Cr, Fe, Co, Ni, Cu or the like.

LiXMPO ₄ (wherein, M is Mn, Fe, Co, Ni, Cu, Mg, Zn, V, Ca, Sr, Ba, Ti, Al, Si, LiXMPO ₄ as the lithium-containing composite metal oxide having an olivine structure) An olivine type lithium phosphate compound represented by at least one selected from B and Mo, 0 ≦ X ≦ 2).

  As the organic compound, for example, a conductive polymer such as polyacetylene or poly-p-phenylene can be used.

  An iron-based oxide having poor electrical conductivity may be used as an electrode active material covered with a carbon material by allowing a carbon source material to be present during reduction firing. These compounds may be partially element-substituted. The positive electrode active material for a lithium ion secondary battery may be a mixture of the above inorganic compound and organic compound.

  In the present invention, the particle diameter of the active material used is usually 1 to 50 μm, preferably 2 to 30 μm. When the particle diameter is in the above range, the amount of the binder when preparing the slurry composition to be described later can be reduced, the decrease in the capacity of the battery can be suppressed, and the slurry composition is suitable for coating. It becomes easy to adjust the viscosity, and a uniform electrode can be obtained.

  The amount of the active material used is usually 1 to 1000 times, preferably 2 to 500 times, more preferably 3 to 500 times, and particularly preferably 5 to 300 times based on the weight of the vinyl polymer.

  If necessary, various fillers, organic pigments, inorganic pigments, extender pigments, rust inhibitors and the like can be added to the resin composition for a lithium ion secondary electrode of the present invention. These may be used alone or in combination of two or more.

  Examples of the filler include barium sulfate, barium titanate, silicon oxide powder, finely divided silicon oxide, silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, mica, and alumina. Is mentioned.

  As the filler, those having various particle sizes can be used, and can be added to such an extent that the physical properties of the present resin and its composition are not impaired. Such an appropriate amount is in the range of about 5 to 80% by mass, and preferably used after being uniformly dispersed. As a dispersion method, it is possible to carry out dispersion by a known roll, bead mill, high-speed dispersion or the like, and the surface of the particles may be modified in advance with a dispersion treatment agent.

  Examples of the organic pigment include azo pigments; copper phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green, and quinacridone pigments.

  Examples of the inorganic pigment include chromates such as chrome lead, zinc chromate and molybdate orange; ferrocyanides such as bitumen, titanium oxide, zinc white, bengara, iron oxide; metal oxides such as chromium carbide green, Cadmium yellow, cadmium red; metal sulfides such as mercury sulfide; selenides; sulfates such as lead sulfate; silicates such as ultramarine; carbonates, cobalt biored; phosphates such as manganese purple; aluminum powder, zinc dust Metal powders such as brass powder, magnesium powder, iron powder, copper powder and nickel powder; carbon black and the like.

  In addition, any of other coloring, rust prevention, and extender pigments can be used. These may be used alone or in combination of two or more.

  The lithium ion secondary battery of the present invention has an electrode obtained by using the resin composition of the present invention.

  The electrode is formed, for example, by applying a paste-like mixture containing the composition of the present invention to a metal foil to form a coating layer, followed by drying and pressure bonding.

  The solvent used for the preparation of the mixture preferably contains at least one of N-methyl-2-pyrrolidone, γ-butyrolactone, cyclohexanone, and xylene. Particularly preferred is N-methyl-2-pyrrolidone from the viewpoint of solubility.

  Among the steps of forming the electrode layer, at least the step of drying at a temperature of 125 ° C. or lower until the amount of the solvent contained in the coating layer is 40% or less of the initial content at least at the beginning of the drying step It is preferable to include. Thus, by drying at a low temperature of 125 ° C. or lower until the amount of the solvent is 40% or less of the initial content at least in the initial stage of the drying step, the distribution state of the binder component in the electrode layer is optimized, Through the subsequent drying and pressure-bonding steps, an optimal adhesion state between the electrode layer and the metal foil is obtained, and charge / discharge characteristics are improved.

  The lithium ion secondary battery of the present invention is preferably obtained by using a composition containing a carbon-based active material among the resin compositions of the present invention because an electrode having good conductivity can be obtained.

  The lithium ion secondary battery of the present invention includes a negative electrode obtained using the electrolytic solution and the composition of the present invention, and is manufactured according to a conventional method using parts such as a separator as necessary. For example, the following method is mentioned. That is, the positive electrode and the negative electrode are overlapped via a separator, wound or folded according to the shape of the battery, put into a battery container, injected with an electrolyte, and sealed. The shape of the battery may be any of a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, and the like.

Any electrolyte solution may be used as long as it is generally used for a lithium ion secondary battery, and an electrolyte that functions as a battery may be selected according to the type of the negative electrode active material and the positive electrode active material. As the electrolyte, for example, any conventionally known lithium salt can be used. LiClO ₄ , LiBF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiB10Cl 10, LiAlCl 4, LiCl, LiBr, _{LiB (C2H 5) 4, CF} 3 SO 3 Li, CH 3 SO 3 Li, LiCF 3 SO 3, LiC 4 F 9 S0 3, Li (CF 3 SO 2) 2N, such as a lower fatty acid lithium carboxylate and the like.

  The solvent for dissolving the electrolyte (electrolyte solvent) is not particularly limited as long as it is usually used, but carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, and diethyl carbonate; γ-butyl Lactones such as lactones; ethers such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; 1,3-dioxolane, 4 -Oxolanes such as methyl-1,3-dioxolane; nitrogen-containing compounds such as acetonitrile and nitromethane; methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, etc. Organic acid esters; inorganic acid esters such as phosphoric acid triesters and carbonic acid diesters such as dimethyl carbonate, diethyl carbonate and dipropyl carbonate; diglymes; triglymes; sulfolanes; oxazolidinones such as 3-methyl-2-oxazolidinone A sultone such as 1,3-propane sultone, 1,4-butane sultone, naphtha sultone, etc., or a mixture of two or more of them can be used.

  The present invention will be described below with reference to examples and comparative examples. “Part” and “%” in this example are based on mass unless otherwise specified.

Synthesis Example 1 (Synthesis of vinyl polymer)
Preparation of pre-emulsion 312.0 parts of butyl acrylate (hereinafter abbreviated as BA), 264 parts of styrene, 18 parts of acrylic acid (hereinafter abbreviated as AA) and glycidyl methacrylate (hereinafter abbreviated as GMA) 6.0 Parts: Emulgen A-500 [polyoxyethylene distyrenated phenyl ether (nonionic emulsifier) manufactured by Kao Corporation, polyoxyethylene ether chain content: 90%] 15 parts, Neugen TDS-500F [Daiichi Kogyo Polyoxyethylene tridecyl ether (nonionic emulsifier) manufactured by Pharmaceutical Co., Ltd., Polyoxyethylene ether chain content: 90%, 15 parts, Neogen S-20F [Daiichi Kogyo Seiyaku Co., Ltd. linear alkylbenzene suphon] Sodium acid (anionic emulsifier); active ingredient 20%] and latemul E-118B [Kao Corporation Polyoxyethylene alkyl ether sodium sulfate (anionic emulsifier); 25% active ingredient, polyoxyethylene ether chain content: 76%] An emulsifier obtained by dissolving 6.0 parts in 202.5 parts ion-exchanged water A pre-emulsion (A1) was prepared by dispersing in an aqueous solution.

-Preparation of polymerization initiator solution for dropping 1.5 parts of sodium persulfate and 6 parts of ion exchange water were put in a beaker and sufficiently stirred and dissolved at room temperature to prepare a polymerization initiator solution for dropping (B1). In addition, 1.2 parts of sodium persulfate and 42 parts of ion-exchanged water were placed in a beaker and sufficiently stirred and dissolved at room temperature to prepare a dropping polymerization initiator solution (B2).

Synthesis of vinyl polymer emulsion In a 1 L reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet, 264 parts of ion exchange water, Leocol TD90 [polyethylene glycol nonionic emulsifier manufactured by Lion Corporation, poly Oxyethylene ether chain content: 65%] 6.0 parts were added, and the temperature was raised to 78 ° C. over 30 minutes under a nitrogen seal. After 42.3 parts of pre-emulsion (A1) was added to this reaction vessel and stirred for 5 minutes, a polymerization initiator solution for dropping (B1) was added and reacted at 80 ° C. for 5 minutes. Next, 803.7 parts of the remaining pre-emulsion (A1) and the polymerization initiator solution for dripping (B2) are dropped over 3 hours, and then held for another 60 minutes to lower the electrolyte substance concentration in the system. The mixture was emulsion polymerized while being cooled, and then cooled. Using ammonia water and ion exchange water, the pH was adjusted to 7.6 and the non-volatile content was adjusted to 49.7% to obtain a resin emulsion. This is referred to as (EM-1).

  In this synthesis example, the ratio of the mass of the polyoxyalkylene ether chain in the emulsifier having a polyoxyethylene ether chain to the total amount of the raw materials for the vinyl polymer was 5.2%. Moreover, the usage-amount of the emulsifier which has a polyoxyethylene ether chain was 6.25% with respect to the total amount of the raw material of a vinyl polymer.

Synthesis example 2 (same as above)
-Preparation of pre-emulsion 212.0 parts of butyl acrylate (hereinafter abbreviated as BA), 176 parts of styrene, 15 parts of acrylic acid (hereinafter abbreviated as AA) and 2.0 parts of γ-methacryloxypropyltrimethoxysilane 20 parts of Emulgen A-500 [polyoxyethylene distyrenated phenyl ether (nonionic emulsifier) manufactured by Kao Corporation, polyoxyethylene ether chain content: 90%], Neugen TDS-500F [Daiichi Kogyo Seiyaku Co., Ltd.] Polyoxyethylene tridecyl ether (nonionic emulsifier) manufactured by Co., Ltd., Polyoxyethylene ether chain content: 90%, 20 parts, Neogen S-20F [Daiichi Kogyo Seiyaku Co., Ltd. linear alkylbenzene sulphonic acid] Sodium (anionic emulsifier); 10 parts of active ingredient] and Latemul E-118B [Kao Corporation Sodium polyoxyethylene alkyl ether sulfate (anionic emulsifier): 25% active ingredient, polyoxyethylene ether chain content: 76%] Disperse 8.0 parts in 200 parts of ion-exchanged water in an aqueous solution. To prepare a pre-emulsion (A2).

・ Preparation of polymerization initiator solution for dropping Add 0.25 parts of sodium persulfate and 1.0 part of ion-exchanged water into a beaker and dissolve with sufficient stirring at room temperature to prepare a polymerization initiator solution for dropping (B3). did. Further, 1.0 part of sodium persulfate and 40.0 parts of ion-exchanged water were placed in a beaker and sufficiently stirred and dissolved at room temperature to prepare a polymerization initiator solution for dropping (B4).

Synthesis of vinyl polymer emulsion In a 1 L reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet, 348 parts of ion-exchanged water, Leocol TD90 [polyethylene glycol nonionic emulsifier manufactured by Lion Corporation, poly Oxyethylene ether chain content: 65%] 8.0 parts were added and heated to 78 ° C. over 30 minutes under a nitrogen seal. After adding 33.2 parts of pre-emulsion (A2) to the reaction vessel and stirring for 5 minutes, a polymerization initiator solution (B3) for dropping was added and reacted at 80 ° C. for 5 minutes. Next, 629.8 parts of the remaining pre-emulsion (A2) and the polymerization initiator solution for dropping (B4) are dropped over 3 hours, and then held for another 60 minutes to lower the electrolyte substance concentration in the system. The mixture was emulsion polymerized while being cooled, and then cooled. Using ammonia water and ion-exchanged water, the pH was adjusted to 7.5 and the non-volatile content was 39.3% to obtain a resin emulsion. This is referred to as (EM-2).

  In this synthesis example, the ratio of the mass of the polyoxyalkylene ether chain in the emulsifier having a polyoxyethylene ether chain to the total amount of the raw materials for the vinyl polymer was 10.5%. Moreover, the usage-amount of the emulsifier which has a polyoxyethylene ether chain was 12.4% with respect to the total amount of the raw material of a vinyl polymer.

Synthesis example 3 (same as above)
-Preparation of pre-emulsion 212.0 parts of butyl acrylate (hereinafter abbreviated as BA), 176 parts of styrene, 15 parts of acrylic acid (hereinafter abbreviated as AA) and 2.0 parts of γ-methacryloxypropyltrimethoxysilane 24 parts of Emulgen A-500 [polyoxyethylene distyrenated phenyl ether (nonionic emulsifier) manufactured by Kao Corporation, polyoxyethylene ether chain content: 90%], Neugen TDS-500F [Daiichi Kogyo Seiyaku Co., Ltd. Polyoxyethylene tridecyl ether (nonionic emulsifier) manufactured by Co., Ltd., Polyoxyethylene ether chain content: 90%, 24 parts, Neogen S-20F [Daiichi Kogyo Seiyaku Co., Ltd. linear alkylbenzene sulphonic acid] Sodium (anionic emulsifier); active ingredient 20%] and latemul E-118B [Kao Corporation Sodium polyoxyethylene alkyl ether sulfate (anionic emulsifier); 25% active ingredient, polyoxyethylene ether chain content: 76%] Disperse an emulsifier in 10 parts of ion-exchanged water in 200 parts of an aqueous solution. Thus, a pre-emulsion (A3) was prepared.

・ Preparation of polymerization initiator solution for dripping)
0.25 parts of sodium persulfate and 1.0 parts of ion exchange water were put into a beaker and sufficiently stirred and dissolved at room temperature to prepare a dropping polymerization initiator solution (B5). Further, 1.0 part of sodium persulfate and 40.0 parts of ion exchange water were put into a beaker and sufficiently stirred and dissolved at room temperature to prepare a dropping polymerization initiator solution (B6).

Synthesis of vinyl polymer emulsion In a 1 L reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet, 348 parts of ion-exchanged water, Leocol TD90 [polyethylene glycol nonionic emulsifier manufactured by Lion Corporation, poly Oxyethylene ether chain content: 65%] 10 parts were added and heated to 78 ° C. over 30 minutes under a nitrogen seal. After adding 33.8 parts of pre-emulsion (A3) to this reaction vessel and stirring for 5 minutes, a polymerization initiator solution for dropping (B5) was added and reacted at 80 ° C. for 5 minutes. Next, 641.2 parts of the remaining pre-emulsion (A3) and the polymerization initiator solution for dropping (B2) are dropped over 3 hours, and then held for another 60 minutes, thereby reducing the electrolyte substance concentration in the system. The mixture was emulsion polymerized while being cooled, and then cooled. Using ammonia water and ion-exchanged water, the pH was adjusted to 7.5 and the non-volatile content was 39.3% to obtain a resin emulsion. This is referred to as (EM-3).

  In this synthesis example, the ratio of the mass of the polyoxyalkylene ether chain in the emulsifier having a polyoxyethylene ether chain to the total amount of the raw materials for the vinyl polymer was 12.6%. Moreover, the usage-amount of the emulsifier which has a polyoxyethylene ether chain was 15% with respect to the total amount of the raw material of a vinyl polymer.

Synthesis Example 4 (Synthesis of vinyl polymer for comparison)
Preparation of pre-emulsion 312.0 parts of butyl acrylate (hereinafter abbreviated as BA), 264 parts of styrene, 18 parts of acrylic acid (hereinafter abbreviated as AA) and glycidyl methacrylate (hereinafter abbreviated as GMA) 6.0 Parts: Emulgen A-500 [polyoxyethylene distyrenated phenyl ether (nonionic emulsifier) manufactured by Kao Corporation, polyoxyethylene ether chain content: 90%] 12 parts, Neugen TDS-500F [Daiichi Kogyo Polyoxyethylene tridecyl ether (nonionic emulsifier) manufactured by Pharmaceutical Co., Ltd., polyoxyethylene ether chain content: 90%] 12 parts, Neogen S-20F [Daiichi Kogyo Seiyaku Co., Ltd. linear alkylbenzene suphon] Acid sodium (anionic emulsifier); active ingredient 20%] 6.0 parts and latemul E-118B [Kao Corporation Sodium polyoxyethylene alkyl ether sulfate (anionic emulsifier) manufactured by the company; active ingredient 25%, polyoxyethylene ether chain content: 76%] emulsifier aqueous solution in which 5.0 parts are dissolved in 202.5 parts ion-exchanged water A pre-emulsion (A4) was prepared by dispersing in.

-Preparation of polymerization initiator solution for dropping 1.5 parts of sodium persulfate and 6 parts of ion exchange water were put into a beaker and sufficiently stirred and dissolved at room temperature to prepare a polymerization initiator solution for dropping (B7). In addition, 1.2 parts of sodium persulfate and 42 parts of ion-exchanged water were placed in a beaker and sufficiently stirred and dissolved at room temperature to prepare a dropping polymerization initiator solution (B8).

Synthesis of vinyl polymer emulsion In a 1 L reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet, 264 parts of ion exchange water, Leocol TD90 [polyethylene glycol nonionic emulsifier manufactured by Lion Corporation, poly Oxyethylene ether chain content: 65%] 5.0 parts were added, and the temperature was raised to 78 ° C. over 30 minutes under a nitrogen seal. After adding 41.9 parts of pre-emulsion (A4) to this reaction vessel and stirring for 5 minutes, a polymerization initiator solution for dropping (B7) was added and reacted at 80 ° C. for 5 minutes. Next, 795.6 parts of the remaining pre-emulsion (A4) and the polymerization initiator solution for dropping (B8) are dropped over 3 hours, and then held for another 60 minutes to lower the electrolyte substance concentration in the system. The mixture was emulsion polymerized while being cooled, and then cooled. Using ammonia water and ion-exchanged water, the pH was adjusted to 7.5 and the non-volatile content was adjusted to 49.5% to obtain a resin emulsion. This is referred to as (em-1).

  In this synthesis example, the ratio of the mass of the polyoxyalkylene ether chain in the emulsifier having a polyoxyethylene ether chain to the total amount of the raw materials for the vinyl polymer was 4.3%. Moreover, the usage-amount of the emulsifier which has a polyoxyethylene ether chain was 5% with respect to the total amount of the raw material of a vinyl polymer.

Synthesis example 5 (same as above)
-Preparation of pre-emulsion 212.0 parts of butyl acrylate (hereinafter abbreviated as BA), 176 parts of styrene, 15 parts of acrylic acid (hereinafter abbreviated as AA) and 2.0 parts of γ-methacryloxypropyltrimethoxysilane Emulgen A-500 [Polyoxyethylene distyrenated phenyl ether (nonionic emulsifier) manufactured by Kao Corporation, polyoxyethylene ether chain content: 95%] 28 parts, Neugen TDS-500F [Daiichi Kogyo Seiyaku Co., Ltd. Polyoxyethylene tridecyl ether (nonionic emulsifier) manufactured by Co., Ltd., polyoxyethylene ether chain content: 90%, 28 parts, Neogen S-20F [Daiichi Kogyo Seiyaku Co., Ltd. linear alkylbenzene sulphonic acid] Sodium (anionic emulsifier); active ingredient 20%,] 14 parts and latemul E-118B [Kao Corporation Sodium polyoxyethylene alkyl ether sulfate (anionic emulsifier); 25% active ingredient, polyoxyethylene ether chain content: 76%] Disperse an emulsifier in which 12 parts are dissolved in 200 parts of ion-exchanged water in an aqueous solution. As a result, a pre-emulsion (A5) was prepared.

・ Preparation of polymerization initiator solution for dropping Add 0.25 parts of sodium persulfate and 1.0 part of ion-exchanged water into a beaker and dissolve with sufficient stirring at room temperature to prepare a polymerization initiator solution for dropping (B9). did. Further, 1.0 part of sodium persulfate and 40.0 parts of ion exchange water were placed in a beaker and sufficiently stirred and dissolved at room temperature to prepare a dropping polymerization initiator solution (B10).

Synthesis of vinyl polymer emulsion In a 1 L reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet, 348 parts of ion-exchanged water, Leocol TD90 [polyethylene glycol nonionic emulsifier manufactured by Lion Corporation, poly Oxyethylene ether chain content: 65%] 10 parts were added and heated to 78 ° C. over 30 minutes under a nitrogen seal. After adding 34.4 parts of pre-emulsion (A5) to this reaction vessel and stirring for 5 minutes, a polymerization initiator solution (B9) for dropping was added and reacted at 80 ° C. for 5 minutes. Next, 652.6 parts of the remaining pre-emulsion (A5) and the polymerization initiator solution for dropping (B10) are added dropwise over 3 hours, and then held for another 60 minutes to lower the electrolyte substance concentration in the system. The mixture was emulsion polymerized while being cooled, and then cooled. Using ammonia water and ion-exchanged water, the pH was adjusted to 7.5 and the non-volatile content was 39.3% to obtain a resin emulsion. This resin emulsion was poor in stability and contained aggregates. This is referred to as (em-2).

In this synthesis example, the ratio of the mass of the polyoxyalkylene ether chain in the emulsifier having the polyoxyethylene ether chain to the total amount of the vinyl polymer raw material was 15.5%. Moreover, the usage-amount of the emulsifier which has a polyoxyethylene ether chain was 18.0% with respect to the total amount of the raw material of a vinyl polymer.
Synthesis example 6 (same as above)
Preparation of preemulsion 312.0 parts of butyl acrylate (hereinafter abbreviated as BA), 264 parts of styrene, 18 parts of acrylic acid (hereinafter abbreviated as AA), glycidyl methacrylate (hereinafter abbreviated as GMA) 6.0 Parts, and 14.4 parts of methoxypolyethylene glycol methacrylate (polyoxyethylene ether chain content: 80%), Emulgen A-500 [polyoxyethylene distyrenated phenyl ether (nonionic emulsifier) manufactured by Kao Corporation], Polyoxyethylene ether chain content: 90%] 12 parts, Neugen TDS-500F [Daiichi Kogyo Seiyaku Co., Ltd. polyoxyethylene tridecyl ether (nonionic emulsifier, polyoxyethylene ether chain content: 90%) )] 12 parts, Neogen S-20F [Daiichi Kogyo Seiyaku Co., Ltd. linear alkylben] Zensusulfonate sodium (anionic emulsifier); 6.0 parts of active ingredient] and Latemul E-118B [Polysodium polyoxyethylene alkyl ether sulfate (anionic emulsifier) manufactured by Kao Corporation; 25% active ingredient, polyoxyethylene ether Chain content: 76%] A pre-emulsion (A6) was prepared by dispersing 5.0 parts in an aqueous emulsifier solution dissolved in 202.5 parts of ion-exchanged water.

・ Preparation of polymerization initiator solution for dripping)
1.5 parts of sodium persulfate and 6 parts of ion-exchanged water were placed in a beaker and sufficiently stirred and dissolved at room temperature to prepare a dropping polymerization initiator solution (B7). In addition, 1.2 parts of sodium persulfate and 42 parts of ion-exchanged water were placed in a beaker and sufficiently stirred and dissolved at room temperature to prepare a dropping polymerization initiator solution (B8).

Synthesis of vinyl polymer emulsion In a 1 L reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet, 264 parts of ion exchange water, Leocol TD90 [polyethylene glycol nonionic emulsifier manufactured by Lion Corporation, poly Oxyethylene ether chain content: 65%] 5.0 parts were added, and the temperature was raised to 78 ° C. over 30 minutes under a nitrogen seal. After adding 41.9 parts of pre-emulsion (A4) to this reaction vessel and stirring for 5 minutes, a polymerization initiator solution for dropping (B7) was added and reacted at 80 ° C. for 5 minutes. Next, 795.6 parts of the remaining pre-emulsion (A4) and the polymerization initiator solution for dropping (B8) are dropped over 3 hours, and then held for another 60 minutes to lower the electrolyte substance concentration in the system. The mixture was emulsion polymerized while being cooled, and then cooled. Using ammonia water and ion-exchanged water, the pH was adjusted to 7.5 and the non-volatile content was adjusted to 49.5% to obtain a resin emulsion. This is referred to as (em-3).

  In this synthesis example, the ratio of the mass of polyoxyalkylene ether chain in the emulsifier having polyoxyethylene ether chain (including methoxypolyethylene glycol methacrylate) to the total amount of vinyl polymer raw material (including methoxypolyethylene glycol methacrylate) is The amount of the emulsifier having a polyoxyethylene ether chain (including methoxypolyethylene glycol methacrylate) is 4.0% with respect to the total amount of the vinyl polymer raw materials (including methoxypolyethylene glycol methacrylate). %Met.

Example 1
A resin emulsion (EM-1) according to the present invention having a solid content of 50% in a solid content of 1.5 parts, sodium carboxymethylcellulose, 6.5 parts of acetylene black, and 91 parts of spherical graphite. The resin composition 1 for lithium ion secondary battery electrodes was obtained. After applying the obtained slurry to one side of a 30 μm thick copper foil, it was dried in a hot air oven at 60 ° C. for 10 minutes and further dried under reduced pressure in a hot air oven at 85 ° C. overnight to form an electrode. . The prepared electrode was cooled to room temperature and then pressed so that the electrode density was 1.3 g / cm ³ . The obtained electrode had a thickness of 80 μm including the copper foil.

  The flexibility of the obtained electrode, the adhesion of the electrode copper foil and the cured resin composition, and the cycle characteristics were evaluated according to the following methods.

<Method for evaluating electrode flexibility>
The electrode was cut into a square of 8 cm square to obtain a test piece. This test piece was wound around a rod having a diameter of 2 mm and 10 mm, and the surface of the electrode was visually observed. Evaluation was made according to the following criteria.

(Double-circle): Even if it winds around a 2 mm diameter stick, peeling of copper foil and hardened resin is not seen.
○: The above-mentioned peeling occurs when wound on a rod having a diameter of 2 mm, but the above-mentioned peeling does not occur when wound on a rod having a diameter of 10 mm.
X: The above peeling occurs even when wound on a rod having a diameter of 10 mm.

<Evaluation of adhesion between copper foil of electrode and cured resin composition>
The electrode was cut into a square of 8 cm square to obtain a test piece. Using this test piece, a cross-cut test and an adhesive tape test were conducted and evaluated according to the following criteria.

○: No peeling is observed in a cross cut (100 square) test of 1 mm × 1 mm, and the copper foil is not exposed by subsequent peeling of the adhesive tape.
Δ: No peeling is observed in the cross cut (100 square) test of 1 mm × 1 mm, and the copper foil is exposed partially or almost on the front surface in the subsequent peeling of the adhesive tape.
X: At the time of cross cut (100 squares) of 1 mm x 1 mm, peeling is observed and the copper foil is exposed.

The electrode was cut into a circle having an area of 1.539 cm ² and dried under vacuum at 80 ° C. for 24 hours. This electrode is placed in a nickel-plated iron battery can container so that the electrode layer surface faces a lithium foil through a porous polypropylene film having a thickness of 25 μm, and a six-volume mixture of ethylene carbonate and diethyl carbonate in an equal volume mixture. A non-aqueous electrolyte solution in which lithium phosphate LiPF6 was dissolved at a rate of 1 mol / liter was injected and sealed to prepare a lithium ion secondary battery. About the obtained lithium ion secondary battery, the capacity | capacitance maintenance factor (%) was measured with the following method.

<Measurement method of cycle characteristics [capacity retention rate (%)]>
Charging capacity at the second cycle (unit = mAh / g (per active material)) and charging capacity at the 100th cycle (units) from 0V to 1.5V with a positive electrode made of metal lithium and a constant current constant voltage charging method of 0.2C = MAh / g (per active material)), the ratio of the charge capacity at the 100th cycle to the charge capacity at the 2nd cycle is calculated as a percentage, and this is used as the capacity retention rate (%). The larger this value is, the better the result is.

Examples 2, 3 and Comparative Examples 1-3
Except for using the resin composition (EM-1) of the present invention, (EM-2), (EM-3) and (em-1) to (em-3), respectively, except that each was used as in Example 1. Thus, resin compositions 2 and 3 for lithium ion secondary battery electrodes and resin compositions 1 'to 3' for lithium ion secondary battery electrodes for comparison were obtained. Evaluation was performed in the same manner as in Example 1 using these compositions. The evaluation results are shown in Table 1.

Claims (7)

A resin composition for a lithium ion secondary battery electrode comprising a vinyl polymer obtained by polymerizing a vinyl monomer in the presence of a non-reactive emulsifier having a polyoxyalkylene ether chain and an active material, Lithium ion secondary, wherein the vinyl polymer is obtained using the emulsifier so that the ratio of the mass of the polyoxyalkylene ether chain to the total mass of the vinyl monomer is 5 to 15%. The manufacturing method of the resin composition for battery electrodes. Method of preparing the emulsifier is a lithium-ion secondary battery electrode resin composition according to claim 1, wherein the nonionic emulsifier. The method for producing a resin composition for a lithium ion secondary battery electrode according to claim 2, wherein the nonionic emulsifier is a polyoxyethylene alkyl ether or a polyoxyethylene aryl ether. The method for producing a resin composition for a lithium ion secondary battery electrode according to claim 1, wherein the number of repeating units of the polyoxyethylene ether chain is 5 to 50. 2. The lithium ion catalyst according to claim 1, wherein the vinyl polymer is obtained using the emulsifier such that the ratio of the mass of the polyoxyalkylene ether chain to the total mass of the vinyl monomers is 5 to 13%. The manufacturing method of the resin composition for secondary battery electrodes. The said vinyl polymer is a thing obtained by using 30-90 mass parts of butyl acrylate, 10-70 mass parts of styrene, and 1-10 mass parts of acrylic acid, The any one of Claims 1-5. The manufacturing method of the resin composition for lithium ion secondary battery electrodes. A resin composition for a lithium ion secondary battery electrode comprising a vinyl polymer obtained by polymerizing a vinyl monomer in the presence of a non-reactive emulsifier having a polyoxyalkylene ether chain and a carbon-based active material. A negative electrode obtained by using the composition obtained by using the emulsifier so that the ratio of the mass of the polyoxyalkylene ether chain to the total mass of the vinyl monomer is 5 to 15%. A method for producing a lithium ion secondary battery , comprising: