JP7139342B2 - Electrode mix for non-aqueous electrolyte secondary batteries - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrode mixture for non-aqueous electrolyte secondary batteries and the like.

In recent years, with the spread of portable electronic devices such as laptop computers, smartphones, portable game devices, and PDAs, secondary batteries are used as power sources in order to make these devices lighter and enable them to be used for a long time. There is a demand for miniaturization and high capacity. Furthermore, recently, with emphasis on portability and handling of batteries, rapid charging characteristics that enable charging with a large current in a short period of time have also become an important requirement.

Means for improving the rapid charging characteristics of a lithium secondary battery mainly include improvement of electrode constituent members.

A binder, which is an electrode component, is also one of the components that affect the performance of the secondary battery. A binder is used to firmly fix the structure of the electrode, but using a binder with a higher binding strength and toughness prevents the electrode from collapsing during battery charging and discharging, and improves cycle characteristics (i.e., longer life). Become). However, in general, a binder, which is one of the members constituting an electrode, has lower conductivity than an electrode active material, a conductive aid, and the like, and can cause resistance during charging and discharging. Electrodes cannot be formed with only active materials and conductive aids, and binders are indispensable for bonding members. Therefore, in order to improve battery performance, it is desired to develop an electrode that contains a binder and has a low resistance.

JP 2012-204203 A JP-A-2000-348730

The present invention has been made in view of the current state of the prior art described above, and its main object is to provide an electrode mixture that contains a binder and has a low resistance, and furthermore, to provide an electrode mixture containing a binder. An object of the present invention is to manufacture an electrode and provide an electrode mixture for a non-aqueous electrolyte secondary battery having the electrode.

As a result of intensive studies to solve the above problems, the present inventors have found that a specific binding agent, a specific cross-linking agent, and an electrode active material are included, and in particular, the binding agent and the cross-linking agent are mixed in a specific ratio. By using the electrode mixture for a non-aqueous electrolyte secondary battery contained in, it was found that an electrode with a low resistance value can be produced, and further improvements were repeated to complete the present invention.

The invention includes, for example, the subject matter described in the following sections.
Section 1.
containing an electrode active material, a cross-linking agent, and a binder;
The binder contains a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product,
the cross-linking agent is a metal chelate complex compound,
0.2 parts by mass or more and less than 10 parts by mass of the cross-linking agent is contained with respect to 100 parts by mass of the total amount of the binder and the cross-linking agent.
Electrode mixture for non-aqueous electrolyte secondary batteries.
Section 2.
Item 2. The electrode mixture for non-aqueous electrolyte secondary batteries according to Item 1, wherein the metal chelate complex compound is at least one selected from the group consisting of titanium chelate complex compounds and zirconium chelate complex compounds.
Item 3.
Item 3. The electrode mixture for a non-aqueous electrolyte secondary battery according to Item 1 or 2, wherein the cross-linking agent has two or more functional groups capable of reacting with a carboxyl group and/or a hydroxyl group.
Section 4.
Item 3. The electrode assembly for a non-aqueous electrolyte secondary battery according to Item 1 or 2, wherein the cross-linking agent has two or more identical or different functional groups selected from the group consisting of an alkoxy group and an acylate group. agent.
Item 5.
Item 5. The non-aqueous electrolyte secondary battery according to any one of Items 1 to 4, wherein the neutralized alkali metal ethylenically unsaturated carboxylic acid is a neutralized alkali metal acrylate and/or a neutralized alkali metal methacrylate. Electrode mixture for
Item 6.
Item 6. An electrode for a non-aqueous electrolyte secondary battery using the electrode mixture for a non-aqueous electrolyte secondary battery according to any one of Items 1 to 5.
Item 7.
Item 7. A nonaqueous electrolyte secondary battery comprising the electrode for a nonaqueous electrolyte secondary battery according to Item 6.
Item 8.
Item 8. An electrical device comprising the non-aqueous electrolyte secondary battery according to Item 7.
Item 9.
mixing an electrode active material, a cross-linking agent, and a binder;
Here, the cross-linking agent is a metal chelate complex compound, the binder is a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and the binder and the cross-linking agent are The cross-linking agent is mixed so that 0.2 parts by mass or more and less than 10 parts by mass with respect to the total amount of 100 parts by mass.
A method for producing an electrode mixture for a non-aqueous electrolyte secondary battery.

An electrode using the electrode mixture for a non-aqueous electrolyte secondary battery according to the present invention has high cyclability and a relatively low resistance value after cycling. In other words, by using the binder of the present invention for the electrode, the electrode is prevented from collapsing during battery charging and discharging, and the cycle characteristics are improved (that is, the life is extended), so the resistance after charging and discharging is low (that is, rate characteristics are improved and high output is possible).

An outline of one aspect of the electrode mixture for non-aqueous electrolyte secondary batteries included in the present invention will be shown. An outline of one mode when an electrode is prepared by applying the electrode mixture for a non-aqueous electrolyte secondary battery shown in FIG. 1 to a metal foil, drying, pressing, and heating is shown. An electrode mixture containing a binder containing a cross-linkable resin and an electrode active material, and the fact that when a cross-linking agent is further added to this, it can be the electrode mixture for a non-aqueous electrolyte secondary battery of the present invention, Give an overview.

Each embodiment of the present invention will be described in further detail below.

The electrode mixture for non-aqueous electrolyte secondary batteries included in the present invention contains an electrode active material (positive electrode or negative electrode active material), a cross-linking agent, and a binder. It comprises a copolymer of an alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and the cross-linking agent is a metal chelate complex compound. The binder and the cross-linking agent are contained in a specific ratio (0.2 parts by mass or more and less than 10 parts by mass of the cross-linking agent with respect to 100 parts by mass of the binder). The mixture is a composition (mixture composition) containing each of the above components. Moreover, the mixture is preferably in the form of slurry.

Moreover, the electrode mixture may contain, for example, a liquid medium (preferably water) in addition to the electrode active material, the cross-linking agent, and the binder. Furthermore, a conductive aid, a dispersing aid, and the like may be included.

(Binder)
The binder used in the present invention contains a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product. The copolymer is, for example, a copolymer obtained by copolymerizing a vinyl ester and an ethylenically unsaturated carboxylic acid ester, in the presence of an alkali containing an alkali metal, in a mixed solvent of an aqueous organic solvent and water. It can be obtained by saponifying with That is, vinyl alcohol itself is unstable and cannot be used directly as a monomer. It becomes a mode in which alcohol is polymerized as a monomer.

Examples of the vinyl ester include vinyl acetate, vinyl propionate, and vinyl pivalate. Vinyl acetate is preferred because the saponification reaction proceeds easily. These vinyl esters may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the ethylenically unsaturated carboxylic acid esters include methyl esters, ethyl esters, n-propyl esters, iso-propyl esters, n-butyl esters, and t-butyl esters of acrylic acid and methacrylic acid. Methyl acrylate and methyl methacrylate are preferred because the saponification reaction proceeds easily. These ethylenically unsaturated carboxylic acid esters may be used alone or in combination of two or more.

In addition, if necessary, other ethylenically unsaturated monomers copolymerizable with vinyl esters and ethylenically unsaturated carboxylic acid esters are used in addition to vinyl esters and ethylenically unsaturated carboxylic acid esters, may be copolymerized. A copolymer in which vinyl alcohol is polymerized as a monomer, which is obtained by saponifying the copolymer thus obtained, can also be used as a binder in the present invention.

Furthermore, when copolymerizing the vinyl ester and the ethylenically unsaturated carboxylic acid ester (and optionally the other ethylenically unsaturated monomers), a cross-linking agent may also be combined for copolymerization. In the present invention, a copolymer obtained by saponifying the copolymer thus obtained is also included in the copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and is used as a binder. It can be preferably used as. That is, the copolymer of vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal may be an uncrosslinked resin or a crosslinked resin.

In this specification, the cross-linking agent used for preparing the cross-linked resin obtained in this way is referred to as "intra-resin cross-linking monomer", and the non-aqueous electrolyte secondary battery electrode combination according to the present invention is used. It is conceptually distinguished from the "crosslinking agent" that the agent contains. That is, the electrode mixture for a non-aqueous electrolyte secondary battery according to the present invention contains an electrode active material, a "crosslinking agent", and a binder, and the binder contains a crosslinked resin. Alternatively, an "intra-resin cross-linking monomer" may be used in the preparation of the cross-linkable resin. However, this is merely a conceptual distinction, and the substance used as the "crosslinking agent" and the substance used as the "intra-resin crosslinking monomer" may be the same substance.

Intra-resin cross-linking monomers include those having two or more reactive functional groups capable of copolymerization. The reactive functional group is a reactive functional group capable of copolymerization with a monomer that is a raw material for a copolymer of vinyl alcohol and an ethylenically unsaturated alkali metal neutralized product. Each of the two or more reactive functional groups is incorporated (bonded) into the backbone of another copolymer to crosslink. As the reactive functional group capable of copolymerization, a vinyl group is preferred. As the intra-resin cross-linking monomer, a monomer having two vinyl groups is preferably used. More specifically, the intra-resin cross-linking monomer is preferably divinylbenzene, for example. Further, for example, bifunctional acrylates, bifunctional methacrylates (eg, 2-hydroxy-3-acryloyloxypropyl methacrylate, polyethylene glycol diacrylate, etc.) are preferred. Furthermore, cross-linking agents having two or more vinyl sulfone groups can also be used as intra-resin cross-linking monomers, such as CH ₂ ═CH—SO ₂ —CH ₂ —CO—NH—(CH ₂ ) _n —NH Compounds represented by —CO—CH ₂ —SO ₂ —CH═CH ₂ (where n is a natural number of 1 to 6, with 2 or 3 being particularly preferred) are preferred. Commercial products of such compounds include, for example, VS-B and VS-C manufactured by Fuji Film.

As described above, the electrode mixture for non-aqueous electrolyte secondary batteries included in the present invention contains an electrode active material, a cross-linking agent, and a binder. Here, the electrode mixture for a non-aqueous electrolyte secondary battery is different from the electrode mixture containing the binder containing the crosslinked resin and the electrode active material, and is distinguished. That is, the portion derived from the "intra-resin cross-linking monomer" contained in the cross-linkable resin is not a "cross-linking agent". The intra-resin cross-linking monomer has already been used for cross-linking at the time of preparation of the cross-linkable resin and does not have cross-linking ability (in other words, the intra-resin cross-linking monomer already constitutes the cross-linked portion of the cross-linkable resin). is.

Furthermore, a composition after the electrode mixture for a non-aqueous electrolyte secondary battery included in the present invention is heat-treated and cross-linked with a cross-linking agent (for example, the mixture is applied to a metal plate or metal foil and heat-treated The electrode composition provided in the electrode for a non-aqueous electrolyte secondary battery prepared by the above) is also different from the electrode mixture containing the binder containing the crosslinked resin and the electrode active material, and is distinguished. be. In the composition, the cross-linking agent not only cross-links the copolymer contained in the binder, but also cross-links the copolymer contained in the binder and the electrode active material. can be crosslinked. Furthermore, when the electrode mixture for a non-aqueous electrolyte secondary battery included in the present invention is applied to a metal plate or metal foil and then heat-treated to obtain the composition (for example, when it is an electrode composition ), the cross-linking agent can also bind the metal plate or metal foil and the copolymer or electrode active material contained in the binder. In the electrode mixture containing the binder containing the crosslinkable resin and the electrode active material, a crosslinked portion derived from the intra-resin crosslinkable monomer exists in the crosslinkable resin. It has not been.

An outline of one embodiment of the electrode mixture for non-aqueous electrolyte secondary batteries included in the present invention is shown in FIG. In addition, FIG. 2 shows an outline of one mode when the electrode mixture is coated on a metal foil, dried, pressed, and heated to prepare an electrode. Further, the electrode mixture containing only the binder containing the cross-linkable resin and the electrode active material is different from the electrode mixture for the non-aqueous electrolyte secondary battery of the present invention, but the cross-linking agent is added thereto. FIG. 3 shows an outline of what can be the electrode mixture for the non-aqueous electrolyte secondary battery of the present invention in some cases.

As an example of the saponification reaction in this embodiment, the saponification reaction when a vinyl acetate/methyl acrylate copolymer is 100% saponified with potassium hydroxide (KOH) is shown below.

As shown above, the copolymer of vinyl alcohol and ethylenically unsaturated carboxylic acid alkali metal neutralized product according to the present embodiment is obtained by random copolymerization of vinyl ester and ethylenically unsaturated carboxylic acid ester. It is a substance obtained by saponifying an ester moiety derived from a monomer, and the bond between the monomers is a CC covalent bond. (Hereinafter, it may be described as a vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer saponified product. As is clear from the above description, "/" here indicates random copolymerization. show.)

In the copolymer of the present embodiment, the molar ratio of vinyl ester and ethylenically unsaturated carboxylic acid ester (vinyl alcohol/ethylenically unsaturated carboxylic acid alkali metal neutralized product) is preferably 95/5 to 5/95. , 95/5 to 50/50 is more preferred, and 90/10 to 60/40 is even more preferred. Within the range of 95/5 to 5/95, the polymer obtained after saponification is particularly favorably improved in holding power as a binder.

Therefore, in the obtained copolymer of vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal, the copolymer composition ratio is preferably 95/5 to 5/95, more preferably 95/5 to 50/ 50 is more preferred, and 90/10 to 60/40 is even more preferred.

The neutralized alkali metal ethylenically unsaturated carboxylic acid is preferably at least one selected from the group consisting of neutralized alkali metal acrylates and neutralized alkali metal methacrylates. Examples of the alkali metal of the neutralized alkali metal ethylenically unsaturated carboxylic acid include lithium, sodium, potassium, rubidium, and cesium, with potassium and sodium being preferred. Particularly preferred neutralized alkali metal ethylenically unsaturated carboxylic acids are selected from the group consisting of neutralized sodium acrylate, neutralized potassium acrylate, neutralized sodium methacrylate, and neutralized potassium methacrylate. At least one.

A vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer, which is a precursor of a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, is preferred from the viewpoint of obtaining a powdery copolymer. , Polymerized in a state in which monomers mainly composed of vinyl ester and ethylenically unsaturated carboxylic acid ester are suspended in an aqueous solution of a dispersant containing a polymerization catalyst to obtain polymer particles by a suspension polymerization method. things are preferred.

Examples of the polymerization catalyst include organic peroxides such as benzoyl peroxide and lauryl peroxide, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile, with lauryl peroxide being particularly preferred.

The amount of the polymerization catalyst added is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, even more preferably 0.1 to 3% by mass, relative to the total mass of the monomers. If it is less than 0.01% by mass, the polymerization reaction may not be completed, and if it exceeds 5% by mass, binding of the finally obtained copolymer of vinyl alcohol and neutralized ethylenically unsaturated carboxylic acid alkali metal. The effect may not be sufficient.

As the dispersant used in the polymerization, an appropriate substance may be selected depending on the type and amount of the monomers used. Specifically, polyvinyl alcohol (partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol ), water-soluble polymers such as poly(meth)acrylic acid and its salts, polyvinylpyrrolidone, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose; water-insoluble inorganic compounds such as calcium phosphate and magnesium silicate. These dispersants may be used alone or in combination of two or more.

The amount of the dispersant used depends on the type of monomer used, etc., but is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, based on the total mass of the monomers. .

Further, water-soluble salts such as alkali metals and alkaline earth metals can be added in order to adjust the surface active effect of the dispersant. Examples include sodium chloride, potassium chloride, calcium chloride, lithium chloride, anhydrous sodium sulfate, potassium sulfate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, trisodium phosphate and tripotassium phosphate. A salt may be used individually by 1 type, and may be used in combination of 2 or more type.

The amount of the water-soluble salt used depends on the type and amount of the dispersant used, but is usually 0.01 to 10% by mass based on the mass of the aqueous dispersant solution.

The temperature for polymerizing the monomers is preferably -20 to 20°C, more preferably -10 to 10°C, relative to the 10-hour half-life temperature of the polymerization catalyst. For example, the 10-hour half-life temperature of lauryl peroxide is about 62°C.

When the 10-hour half-life temperature is less than -20°C, the polymerization reaction may not be completed. may not have sufficient binding effect.

The time for polymerizing the monomers depends on the type and amount of the polymerization catalyst used, the polymerization temperature, etc., but is usually several hours to several tens of hours.

After completion of the polymerization reaction, the copolymer is separated by a method such as centrifugation or filtration to obtain a water-containing cake. The obtained hydrous cake-like copolymer can be used for the saponification reaction as it is or, if necessary, dried.

The number average molecular weight of a polymer in this specification is a value determined by a molecular weight measuring apparatus equipped with a GFC column (for example, OHpak manufactured by Shodex) using DMF as a solvent. Examples of such a molecular weight measuring device include Waters 2695 and RI detector 2414.

The number average molecular weight of the copolymer before saponification is preferably 10,000 to 1,000,000, more preferably 50,000 to 800,000. By setting the number average molecular weight in the range of 10,000 to 1,000,000 before saponification, there is a tendency that the binding strength of the binder is further improved. Therefore, even if the electrode mixture (particularly the negative electrode mixture) is a water-based slurry, thick application of the slurry is facilitated.

The saponification reaction can be carried out, for example, in the presence of an alkali containing an alkali metal, in an aqueous organic solvent alone, or in a mixed solvent of an aqueous organic solvent and water. As the alkali containing an alkali metal used in the saponification reaction, conventionally known alkalis can be used, but alkali metal hydroxides are preferable, and from the viewpoint of high reactivity, sodium hydroxide and potassium hydroxide is particularly preferred.

The amount of the alkali is preferably 60-140 mol %, more preferably 80-120 mol %, relative to the number of moles of the monomer. If the amount of alkali is less than 60 mol %, the saponification may be insufficient, and even if it exceeds 140 mol %, no further effect is obtained and it is not economical.

For the saponification reaction, it is preferable to use only an aqueous organic solvent or a mixed solvent of an aqueous organic solvent and water. Examples of the aqueous organic solvent include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol and t-butanol; ketones such as acetone and methyl ethyl ketone; and mixtures thereof. Lower alcohols are preferred, and methanol is particularly preferred because it gives a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product having excellent binding effect and excellent resistance to mechanical shearing. and ethanol are preferred.

The aqueous organic solvent/water mass ratio in the mixed solvent of the aqueous organic solvent and water is preferably 30/70 to 85/15, more preferably 40/60 to 85/15, and further 40/60 to 80/20. preferable. If it deviates from the range of 30/70 to 85/15, the solvent affinity of the copolymer before saponification or the solvent affinity of the copolymer after saponification will be insufficient, and the saponification reaction will proceed sufficiently. may not be possible. When the ratio of the aqueous organic solvent is less than 30/70, not only does the binding strength as a binder decrease, but the viscosity increases significantly during the saponification reaction, so it is industrially used as a vinyl ester/ethylenically unsaturated carboxylic acid. It is difficult to obtain a saponified ester copolymer, and if the aqueous organic solvent is more than the ratio of 85/15, the obtained vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer saponified product has low water solubility. If used for , the adhesive strength after drying may be impaired. When the hydrous cake-like copolymer is directly used for the saponification reaction, the mass ratio of aqueous organic solvent/water includes the water in the hydrous cake-like copolymer.

The temperature for saponifying the vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer is preferably, for example, 20 to 60°C, more preferably 20 to 50°C, although it depends on the molar ratio of the monomers. If the saponification is performed at a temperature lower than 20°C, the saponification reaction may not be completed, and if the temperature exceeds 60°C, the inside of the reaction system may become viscous and cannot be stirred.

The saponification reaction time varies depending on the type and amount of alkali used, but the reaction is usually completed in about several hours.

When the saponification reaction is completed, it usually becomes a dispersion of the saponified copolymer in the form of paste or slurry. Solid-liquid separation is performed by a conventionally known method such as centrifugation or filtration, and the liquid-containing copolymer saponified product obtained by thoroughly washing with a lower alcohol such as methanol is dried to obtain spherical single particles or spherical particles. A copolymer saponified product, that is, a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product can be obtained as aggregated aggregated particles.

After the saponification reaction, the saponified copolymer is acid-treated with an acid such as inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid; organic acids such as formic acid, acetic acid, oxalic acid and citric acid. Using any alkali metal such as lithium oxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, dissimilar (that is, different alkali metals) vinyl alcohol and ethylenically unsaturated carboxylic acid Copolymers of neutralized acid alkali metals can also be obtained.

The conditions for drying the saponified liquid-containing copolymer are not particularly limited, but it is usually preferable to dry at a temperature of 30 to 120° C. under normal pressure or reduced pressure.

The drying time is usually several hours to several tens of hours depending on the pressure and temperature during drying.

The volume average particle size of the copolymer of vinyl alcohol and neutralized ethylenically unsaturated carboxylic acid alkali metal is preferably 1 to 200 μm, more preferably 10 to 100 μm. When the thickness is 1 μm or more, a more preferable binding effect can be obtained, and when the thickness is 200 μm or less, the water-based thickened liquid becomes more uniform and a preferable binding effect can be obtained. In addition, the volume average particle diameter of the copolymer was measured by installing a batch cell (eg, SALD-BC manufactured by Shimadzu Corporation) in a laser diffraction particle size distribution analyzer (eg, SALD-7100 manufactured by Shimadzu Corporation). - Values measured using propanol or methanol.

When the liquid-containing saponified copolymer is dried and the resulting saponified copolymer has a volume average particle size of more than 100 μm, it is pulverized by a conventionally known pulverization method such as mechanical milling to obtain volume average particles. The diameter can be adjusted, for example, from 10 to 100 μm.

Mechanical milling is a method of applying an external force such as impact, tension, friction, compression, shear, etc. to the saponified copolymer. Mills, horizontal mills, attritor mills, jet mills, grinders, homogenizers, fluidizers, paint shakers, mixers and the like. For example, in a planetary mill, a saponified copolymer and balls are put together in a container, and the saponified copolymer powder is pulverized or mixed by mechanical energy generated by rotating and revolving. This method is known to pulverize to nano-order.

As the thickening effect in the binder of the copolymer of vinyl alcohol and the neutralized alkali metal ethylenically unsaturated carboxylic acid, the copolymer of vinyl alcohol and the neutralized alkali metal ethylenically unsaturated carboxylic acid is used. The viscosity of an aqueous solution containing 1% by mass is preferably 30 mPa·s to 10000 mPa·s, more preferably 40 to 5000 mPa·s. When the viscosity is 30 mPa·s or more, the viscosity of the prepared slurry electrode mixture is preferably obtained, and when the mixture is applied to a current collector, the mixture does not spread excessively and can be easily applied. The dispersibility of the active material and conductive aid in the agent is also improved. When the viscosity is 10,000 mPa·s or less, the viscosity of the mixture prepared is not too high, and it becomes easier to thinly and uniformly coat the current collector. The viscosity of the 1% by mass aqueous solution was measured using a BROOKFIELD rotational viscometer (model DV-I+), spindle No. It is a value measured at 5 and 50 rpm (liquid temperature 25°C).

A copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product can function as a binder for lithium ion secondary battery electrodes, which is excellent in binding strength and binding durability. The reason for this is that the copolymer of vinyl alcohol and the neutralized product of an ethylenically unsaturated carboxylic acid alkali metal strengthens the current collector, the active material, and the active materials themselves, although this is not intended to be a limited interpretation. By binding and having durability such that the electrode mixture will not peel off from the current collector or the active material will not fall off due to changes in the volume of the active material caused by repeated charging and discharging. , the capacity of the active material is not lowered.

In the lithium ion secondary battery electrode mixture (preferably electrode slurry) of the present embodiment, vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product are added as binders within a range that does not impair the effects of the present invention. Another water-based binder may be added to the copolymer with. In this case, the amount of the other water-based binder to be added is 80% by mass based on the total weight of the copolymer of vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal and the other water-based binder. It is preferably less than More preferably, it is less than 70% by mass. That is, in other words, the content of the copolymer of vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal in the binder is preferably 20% by mass or more and 100% by mass or less. Preferably, it is 30% by mass or more and 100% by mass or less. Furthermore, the lower limit may be, for example, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more.

Other water-based binder materials include, for example, carboxymethyl cellulose (CMC), acrylic resins such as polyacrylic acid, sodium polyacrylate and polyacrylate, sodium alginate, polyimide (PI), polytetrafluoroethylene ( PTFE), polyamide, polyamideimide, styrene-butadiene rubber (SBR), polyvinyl alcohol (PVA), ethylene acetate copolymer (EVA), and the like. These may be used individually by 1 type, and may use 2 or more types together. Among other water-based binders, acrylic resins represented by sodium polyacrylate, sodium alginate, polyimide and the like are preferably used, and acrylic resins are particularly preferably used.

(crosslinking agent)
The cross-linking agent used in the present invention is a metal chelate complex compound having cross-linking ability. Examples of the metal chelate complex compound include titanium chelate complex compounds, zirconium chelate complex compounds, and aluminum chelate complex compounds. Among them, titanium chelate complex compounds and zirconium chelate complex compounds are preferred, and titanium chelate complex compounds are more preferred.

The cross-linking agent (metal chelate complex compound) is a cross-linking agent having two or more (preferably 2, 3, or 4, more preferably 2) functional groups capable of reacting with carboxyl groups and/or hydroxyl groups. preferable. Moreover, the cross-linking agent is preferably a water-based cross-linking agent (water-soluble cross-linking agent). A functional group capable of reacting with a carboxyl group and/or a hydroxyl group refers to a functional group that reacts with a carboxyl group and/or a hydroxyl group to form a chemical bond. Like an alkoxy group, even if it is eliminated by a reaction, it is included if a bond is formed as a result. The necessity of a catalyst and the necessity of heating are not particularly limited. Preferred examples of such functional groups include an alkoxy group and an acylate group. The alkoxy group, for example, has 1 to 18 carbon atoms (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18) and straight or branched chain alkoxy groups. The acylate group includes, for example, a lactate group, a stearate group, an isostearate group and the like.

These functional groups react with the carboxyl groups and/or hydroxyl groups in the molecular chain of the copolymer of vinyl alcohol and the neutralized alkali metal ethylenically unsaturated carboxylic acid to give The copolymer with the hydrate is crosslinked to improve the mechanical strength. Two or more (preferably 2, 3, or 4, more preferably 2) functional groups capable of reacting with carboxyl groups and/or hydroxyl groups are present in the molecule of the cross-linking agent in order to act as a cross-linking agent. There is a need to. The functional groups present in one molecule of the cross-linking agent may be the same or different. The greater the number of functional groups, the greater the number of cross-linking points, which can improve the mechanical strength. is. Whether or not gelation occurs depends on the number of carboxyl groups and/or hydroxyl groups in the molecular chain of the copolymer of vinyl alcohol and the neutralized alkali metal ethylenically unsaturated carboxylic acid, as well as the relationship between the copolymer and the cross-linking agent. Since it also depends on the mixing ratio, it is possible to avoid gelation by adjusting these appropriately.

Examples of cross-linking agents (metal chelate complex compounds) having an alkoxy group and/or an acylate group include metal chelate compounds such as ORGATICS series manufactured by Matsumoto Fine Chemicals Co., Ltd.

Specific examples of titanium chelate complex compounds include titanium lactate ammonium salt, titanium lactate, titanium triethanolamine, titanium diethanolamine, titanium aminoethylaminoethanolate, titanium acetylacetonate, titanium tetraacetylacetonate, titanium Ethyl acetoacetate, titanium dodecylbenzenesulfonate compound, titanium phosphate compound, titanium octylene glycolate, titanium ethyl acetoacetate and the like are preferable, and among them, titanium lactate ammonium salt, titanium lactate, titanium triethanolamine, titanium diethanolamine. , and titanium aminoethylaminoethanolate are more preferred. More specifically, for example, (iC ₃ H ₇ O) ₂ Ti(C ₆ H ₁₄ NO ₃ ) ₂ , (HO) ₂ Ti[OCH(CH ₃ )COO ⁻ ] ₂ (NH ₄ ⁺ ) ₂ , (HO) ₂ Ti[OCH(CH ₃ )COOH] ₂ , (iC ₃ H ₇ O) Ti(OC ₂ H ₄ NHC ₂ H ₄ NH ₂ ) ₃ , (iC ₃ H ₇ O) ₂ Ti (C ₆ H ₇ O ₂ ) ₂ , Ti(C ₅ H ₇ O ₂ ) ₄ , (iC ₃ H ₇ O) ₂ Ti(C ₆ H ₉ O ₃ ) ₂ , Ti(Oi-C ₃ H ₇ ) ₄ , (C ₈ H ₁₇ O) ₂ Ti(O ₂ C ₈ H ₁₇ ) ₂ , (iC ₃ H ₇ O) ₂ Ti(C ₆ H ₉ O ₃ ) ₂ and the like.

Commercially available products of such titanium chelate complex compounds include, for example, the Orgatics TC series manufactured by Matsumoto Fine Chemicals Co., Ltd. More specifically, for example, Orgatics TC-300, TC-310, TC-400 and TC. -315, TC-335, TC-500, and TC-510.

Zirconium chelate complex compounds include, for example, zirconyl chloride compounds, zirconium lactate ammonium salts, zirconium ammonium carbonate, and the like. More specific examples include (HO)Zr[OCH(CH ₃ )COO ⁻ ] ₃ (NH ₄ ⁺ ) ₃ and the like.

Commercially available products of such zirconium chelate complex compounds include, for example, Matsumoto Fine Chemicals Co., Ltd.'s ORGATICS ZA series, ORGATICS ZC series (eg, ORGATICS ZC-126, ZC-300, etc.) and San Nopco Co., Ltd.'s AZ Coat. 5800MT etc. are mentioned.

Examples of aluminum chelate complex compounds include aluminum trisacetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum trisethylacetoacetate, and more specifically Al(C ₅ H ₇ O ₂ ) ₃ . _{, Al ( C5H7O2} ) _{( C6H9O3} ) ₂ and _{Al ( C6H9O3} ) ₃ .

Commercially available products of such organoaluminum compounds include, for example, ORGATICS AL series manufactured by Matsumoto Fine Chemicals Co., Ltd.

A crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

The content of the cross-linking agent is 0.2 parts by mass or more and less than 10 parts by mass when the total mass of the cross-linking agent and the binder is 100 parts by mass. It is more preferably 0.3, 0.4, or 0.5 parts by mass or more, and even more preferably 0.6, 0.7, 0.8, 0.9, or 1 part by mass or more. Further, it is more preferably 9, 8, 7 or 6 mass parts or less, even more preferably 5 or 4 mass parts or less, and even more preferably 3 mass % or less. When the content ratio of the cross-linking agent is less than 10 parts by mass, the gelation of the electrode coating solution is less likely to proceed, and coating can be performed easily. Furthermore, the electrical resistance value of the electrode obtained by relatively increasing the ratio of the active material can be particularly favorably lowered. In addition, when the content ratio of the cross-linking agent is 0.2 parts by mass or more, the cross-linking effect is sufficiently exhibited, and the mechanical strength of the binder resin is high, and favorable battery performance is preferably obtained.

(Positive electrode active material)
As the positive electrode active material, a positive electrode active material used in this technical field can be used. For example, lithium iron phosphate ( _LiFePO4 ), lithium manganese phosphate ( _LiMnPO4 ), lithium cobalt phosphate ( _LiCoPO4 ), iron pyrophosphate _{( Li2FeP2O7} ), lithium _cobaltate composite oxide ₍ LiCoO2 ), spinel-type lithium manganate composite oxide (LiMn ₂ O ₄ ), lithium manganate composite oxide (LiMnO ₂ ), lithium nickelate composite oxide (LiNiO ₂ ), lithium niobate composite oxide (LiNbO ₂ ), lithium ferrate composite oxide (LiFeO ₂ ), lithium magnesium oxide composite oxide (LiMgO ₂ ), lithium calcium oxide composite oxide (LiCaO ₂ ), lithium cuprate composite oxide (LiCuO ₂ ), lithium zincate composite oxide (LiZnO ₂ ), lithium molybdate composite oxide (LiMoO ₂ ), lithium tantalate composite oxide (LiTaO ₂ ), lithium tungstate composite oxide (LiWO ₂ ), lithium-nickel-cobalt-aluminum composite oxide (LiNi _0.8 Co _0.15 Al _0.05 O ₂ ), lithium-nickel-cobalt-manganese composite oxide (LiNi _x Co _y Mn _1-x-y O ₂ where 0<x<1,0<y< 1, x+y<1), Li excess nickel-cobalt-manganese composite oxide, manganese nickel oxide (LiNi _0.5 Mn _1.5 O ₄ ), manganese oxide (MnO ₂ ), vanadium oxide, sulfur oxide materials, silicate-based oxides, and the like are preferably used. These can be used individually by 1 type or in combination of 2 or more types.

(Negative electrode active material)
The negative electrode active material is not particularly limited. A material capable of intercalating and deintercalating a large amount of lithium ions can be used as the material. As long as such materials are used, the effects of the present embodiment can be exhibited regardless of whether the material is a simple substance, an alloy, a compound, a solid solution, or a composite active material containing a silicon-containing material or a tin-containing material. As the silicon-containing material, in addition to Si (silicon), silicon oxide (preferably SiOx (0.05<x<1.95), more specifically, for example, SiO), or any of these with B, Mg , Ni, Ti, Mo, Co, Ca, Cr, Cu, Fe, Mn, Nb, Ta, V, W, Zn, C, N, and Sn. Partially substituted alloys, compounds, or solid solutions can be used. These can be referred to as silicon compounds. Examples of tin-containing materials include Ni ₂ Sn ₄ , Mg ₂ Sn, SnOx (0<x<2), SnO ₂ , SnSiO ₃ and LiSnO. As the carbon material, crystalline carbon, amorphous carbon, or both of them may be used. These materials can be used singly or in combination of two or more. In particular, at least one selected from the group consisting of silicon, silicon compounds and carbon materials is preferred. In particular, when silicon and/or a silicon compound and a carbon material are used in combination, the ratio of the carbon material to the silicon and/or silicon compound (carbon material/silicon or silicon compound) is 5/95 to 50 by mass. /50 is preferred. The upper limit of the mass ratio may be 10/90 or 15/85. Also, the lower limit of the mass ratio may be 40/60, 35/65, 30/70, or 25/75.

(Conductivity aid)
When using a conductive aid, the conductive aid is not particularly limited as long as it has conductivity. For example, powders of metals, carbon, conductive polymers, conductive glasses, etc. can be exemplified, acetylene black (AB), ketjen black (KB), carbon black (for example, SuperP (SP)), graphite, thermal black, furnace black, lamp black, channel black, roller black, disc black, soft carbon, hard carbon, graphene, amorphous carbon nanotubes (CNT), carbon nanofibers (e.g. Vapor Grown Carbon Fiber under the registered trademark VGCF) etc. These may be used singly or in combination of two or more. Although not particularly limited, the conduction aid is preferably contained in the electrode mixture at, for example, about 0.01 to 5% by mass, and more preferably about 0.02 to 3% by mass or 0.05 to 2% by mass. preferable.

(dispersion aid)
When a dispersing aid is used, examples of the dispersing aid include glucuronic acid, humic acid, glycine, polyglycine, aspartic acid, glutamic acid and the like.

(electrode mixture)
A cross-linking agent, a binder, and, if necessary, a liquid medium (preferably water) are added to the electrode active material (positive electrode active material or negative electrode active material) to form a paste-like slurry to form an electrode mixture (positive electrode mixture). agent or negative electrode mixture) is obtained. The binder may be used by dissolving it in water in advance, or the powder of the active material and the binder may be mixed in advance, and then water may be added and mixed. Also, when adding other components, they can be mixed into the slurry.

The amount of the liquid medium (preferably water) used is not particularly limited, but for example, when the total of the active material, the cross-linking agent, and the binder is 100% by mass, the amount is 40% by mass or more and 2000% by mass or less. More preferably 50% by mass or more and 1000% by mass or less, and even more preferably 60% by mass or more and 500% by mass or less.
A binder is used for the purpose of bonding active materials to each other and bonding them to a current collector. That is, it is used to form a good active material layer when the slurry is applied on both current collectors and dried.

The amount of the binder used is also not particularly limited, but for example, it is preferably 0.5% by mass or more with respect to the total mass of the electrode active material, the cross-linking agent, and the binder, and 1 mass % or more, more preferably 2% by mass or more. Also, it is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less. When the amount of the binder is equal to or less than the upper limit, the proportion of the active material is not relatively too small, and a high capacity can be obtained during charging and discharging of the battery. Moreover, when it is at least the lower limit, a more preferable binding force can be obtained, preferable cycle life characteristics can be obtained, and the tendency of aggregation due to insufficient viscosity of the slurry to occur is reduced.

The electrode mixture may be a positive electrode mixture or a negative electrode mixture, and is particularly preferably a negative electrode mixture.

Although not particularly limited, in the electrode mixture, the content of the electrode active material is preferably 80% by mass or more, more preferably 85% by mass or more, and more preferably 90% by mass or more. More preferred.

Although not particularly limited, the total content of the cross-linking agent and the binder in the electrode mixture is preferably less than 20% by mass, more preferably less than 15% by mass, and less than 10% by mass. More preferred.

(positive electrode)
The positive electrode can be made using techniques used in the art.

The current collector of the positive electrode is not particularly limited as long as it is a material that has electronic conductivity and can conduct electricity to the retained positive electrode material. For example, conductive substances such as C, Ti, Cr, Mo, Ru, Rh, Ta, W, Os, Ir, Pt, Au, Al, alloys containing two or more of these conductive substances (for example, stainless steel ) can be used. From the viewpoints of high electrical conductivity, good stability in the electrolyte, and good oxidation resistance, the current collector is preferably C, Al, stainless steel, or the like, and from the viewpoint of material cost, Al or the like is preferable.

The shape of the current collector is not particularly limited, but a foil-like base material, a three-dimensional base material, or the like can be used. However, if a three-dimensional substrate (metal foam, mesh, woven fabric, non-woven fabric, expanded, etc.) is used, an electrode with a high capacitance density can be obtained even with a binder that lacks adhesion to the current collector. . In addition, high rate charge/discharge characteristics are also improved.

(negative electrode)
The negative electrode can be made using techniques used in this technical field.

The current collector of the negative electrode is not particularly limited as long as it is a material that has electronic conductivity and can conduct electricity to the retained negative electrode material. For example, conductive substances such as C, Cu, Ni, Fe, V, Nb, Ti, Cr, Mo, Ru, Rh, Ta, W, Os, Ir, Pt, Au, Al, and two types of these conductive substances Alloys (eg, stainless steel) containing the above may be used. Alternatively, Fe may be plated with Cu. From the viewpoints of high electrical conductivity, good stability in the electrolytic solution, and good oxidation resistance, the current collector is preferably C, Ni, stainless steel, or the like, and more preferably Cu or Ni from the viewpoint of material cost.

The shape of the current collector is not particularly limited, but a foil-like base material, a three-dimensional base material, or the like can be used. Among them, when a three-dimensional base material (foam metal, mesh, woven fabric, non-woven fabric, expanded base material, etc.) is used, even with a binder that lacks adhesion to the current collector, an electrode with a high capacity density can be obtained. is obtained. In addition, high rate charge/discharge characteristics are also improved.

(battery)
A non-aqueous electrolyte secondary battery of the present embodiment can be obtained by using the electrode for the non-aqueous electrolyte secondary battery of the present embodiment. As the nonaqueous electrolyte secondary battery, for example, a lithium ion secondary battery is preferable.

Among the non-aqueous electrolyte secondary batteries of the present embodiment, a lithium ion secondary battery needs to contain lithium ions, and therefore lithium salts are preferable as the electrolyte salt. This lithium salt is not particularly limited, but specific examples include lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, and lithium trifluoromethanesulfonate imide. . These lithium salts can be used singly or in combination of two or more. Since the above lithium salt has high electronegativity and is easily ionized, it is excellent in charge-discharge cycle characteristics and can improve the charge-discharge capacity of the secondary battery.

As the solvent for the electrolyte, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone and the like can be used, and these solvents can be used alone or in combination of two or more. Propylene carbonate alone, a mixture of ethylene carbonate and diethyl carbonate, or γ-butyrolactone alone is particularly preferred. The mixing ratio of the mixture of ethylene carbonate and diethyl carbonate can be arbitrarily adjusted within the range of 10% by volume or more and 90% by volume or less of one of the components.

Also, the electrolyte of the lithium secondary battery of the present embodiment may be a solid electrolyte or an ionic liquid.

The lithium secondary battery having the structure described above can function as a lithium secondary battery with excellent life characteristics.

Although the structure of the lithium secondary battery is not particularly limited, it can be applied to existing battery forms and structures such as stacked batteries and wound batteries.

(Electrical equipment)
The non-aqueous electrolyte secondary battery equipped with the negative electrode of the present embodiment has excellent life characteristics and can be used as a power source for various electric devices (including vehicles that use electricity).

Examples of electrical equipment include portable TVs, notebook computers, tablets, smartphones, computer keyboards, computer displays, desktop computers, CRT monitors, computer racks, printers, integrated computers, wearable computers, word processors, mice, hard disks, and personal computers. Peripherals, irons, air conditioners, refrigerators, hot air heaters, hot carpets, clothes dryers, futon dryers, humidifiers, dehumidifiers, window fans, blowers, ventilation fans, toilet seats with washing function, car navigation systems, flashlights, lighting equipment , portable karaoke machine, microphone, air purifier, sphygmomanometer, coffee grinder, coffee maker, kotatsu, mobile phone, game machine, music recorder, music player, disc changer, radio, shaver, juicer, shredder, water purifier, dish dryer machine, car components, stereo, speakers, headphones, walkie-talkie, trouser press, vacuum cleaner, body fat scale, weight scale, health meter, movie player, electric kettle, electric razor, desk lamp, electric pot, electronic game console, portable game console , electronic dictionary, electronic notebook, electromagnetic cooker, calculator, electric cart, electric wheelchair, electric tools, electric toothbrush, hair paste, haircutting equipment, telephone, clock, intercom, electric insect killer, hot plate, toaster, dryer, electric drill , water heater, panel heater, grinder, soldering iron, video camera, facsimile machine, food processor, massage machine, miniature light bulb, mixer, sewing machine, rice cake maker, remote control, water cooler, cooler, whisk, electronic instrument , motorcycles, toys, lawn mowers, floats, bicycles, automobiles, hybrid automobiles, plug-in hybrid automobiles, electric automobiles, railroads, ships, airplanes, emergency storage batteries, and the like.

In this specification, the term "comprising" includes "consisting essentially of" and "consisting of."

Also, the various characteristics (property, structure, function, etc.) described for each of the embodiments of the invention described above may be combined in any way to identify subject matter encompassed by the invention. That is, the invention encompasses all subject matter consisting of any and all possible combinations of the features described herein.

EXAMPLES The present embodiment will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. Note that Gr indicates graphite.

(Preparation of binder)
(Production Example 1) Synthesis of Vinyl Ester/Ethylenically Unsaturated Carboxylic Acid Ester Copolymer 768 g of water was added to a 2 L reaction vessel equipped with a stirrer, thermometer, _N2 gas inlet tube, reflux condenser and dropping funnel. , and 12 g of anhydrous sodium sulfate were charged, and N ₂ gas was blown to deoxygenate the system. Subsequently, 1 g of partially saponified polyvinyl alcohol (degree of saponification 88%) and 1 g of lauryl peroxide were charged and the internal temperature was raised to 60° C., followed by 104 g (1.209 mol) of methyl acrylate and 155 g (1.802 mol) of vinyl acetate. was added dropwise from the dropping funnel over 4 hours, and the internal temperature was kept at 65° C. for 2 hours to complete the reaction. After that, 288 g of a vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer (water content of 10.4% by mass) was obtained by filtering off the solid content. The obtained polymer was dissolved in DMF and then filtered with a filter. The number average molecular weight determined by a molecular weight measuring device (2695 manufactured by Waters, RI detector 2414) was 188,000.

(Production Example 2) Preparation of saponified vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer Into the same reaction tank as above, 450 g of methanol, 420 g of water, 132 g (3.3 mol) of sodium hydroxide, and the 288 g of the obtained hydrous copolymer (water content of 10.4% by mass) was charged, and saponification reaction was carried out at 30° C. for 3 hours while stirring. After completion of the saponification reaction, the resulting saponified copolymer was washed with methanol, filtered and dried at 70° C. for 6 hours to give a saponified copolymer of vinyl ester/ethylenically unsaturated carboxylic acid ester (vinyl alcohol and ethylene 193 g of a copolymer with a polyunsaturated carboxylic acid neutralized with an alkali metal (alkali metal is sodium) was obtained. The volume average particle size of the vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer saponified product was 180 μm. The volume average particle diameter was measured by a laser diffraction particle size distribution analyzer (SALD-7100 manufactured by Shimadzu Corporation).

(Production Example 3) Pulverization of the saponified vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer 193 g of the saponified vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer was placed in a jet mill (manufactured by Nippon Pneumatic Industry Co., Ltd.). LJ) to obtain 173 g of finely powdered vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer saponified product. The particle size of the resulting saponified copolymer was measured with a laser diffraction particle size distribution analyzer (SALD-7100 manufactured by Shimadzu Corporation), and the volume average particle size was 39 μm. In the following, the saponified vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer obtained in Production Example 3 was used in the study as copolymer [1].

The viscosity of a 1 mass % aqueous solution of copolymer [1] was 1,630 mPa·s, and the copolymer composition ratio of vinyl ester and ethylenically unsaturated carboxylic acid ester was 6/4 in terms of molar ratio. The viscosity of the 1% by mass aqueous solution was measured using a rotational viscometer manufactured by BROOKFIELD (model DV-I+). Measured under conditions of 5 and 50 rpm (liquid temperature 25°C).

(Production example 4)
In Production Example 1, 25.9 g (0.301 mol) of methyl acrylate and 232.8 g (2.704 mol) of vinyl acetate were substituted for 104 g (1.209 mol) of methyl acrylate and 155 g (1.802 mol) of vinyl acetate. A vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer saponified product was obtained in the same manner as in Production Examples 1 to 3 except that the copolymer was used. The vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer saponified product was designated as copolymer [2].

The volume average particle size of copolymer [2] was 34 μm. The viscosity of a 1 mass % aqueous solution of copolymer [2] was 50 mPa·s, and the copolymer composition ratio of vinyl ester and ethylenically unsaturated carboxylic acid ester was 9/1. The volume average particle size and the viscosity of a 1% by mass aqueous solution were measured in the same manner as for copolymer [1].

(Examination of amount of cross-linking agent)
(Example 1)
SiO (average particle size 5-10 μm: manufactured by Hitachi Chemical Co., Ltd.) 18.8 parts by mass, Gr (G1: manufactured by Jiangxi Shishin Technology Co., Ltd.) 75.2 parts by mass (SiO / Gr = 2/8 mass ratio), SP (SuperP: carbon black manufactured by Timcal) 1.0 parts by mass, copolymer [1] obtained in Production Example 3 4.95 parts by mass, organotitanium compound cross-linking agent (manufactured by Matsumoto Fine Chemicals Co., Ltd., TC-400) 0 05 parts by mass and 100 parts by mass of water were mixed to prepare a negative electrode mixture slurry.

After the resulting mixture was applied to an electrolytic copper foil having a thickness of 10 μm and dried, pressure was applied using a roll press (manufactured by Ohno Roll Co., Ltd.) to adhere and bond the electrolytic copper foil and the coating film. Then, heat treatment (120° C. under reduced pressure for 12 hours) was performed to prepare a negative electrode. The active material layer (coating film) had a thickness of 50 μm, and the negative electrode had a basis weight of 10 mg/cm ² .

(Example 2)
In Example 1, instead of 4.95 parts by mass of copolymer [1], 4.9 parts by mass of copolymer [1] was used, and an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) 0 A negative electrode was prepared in the same manner as in Example 1, except that 0.1 part by mass of an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemicals Co., Ltd.) was used instead of 0.05 part by mass. The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

(Example 3)
In Example 1, instead of 4.95 parts by mass of copolymer [1], 4.65 parts by mass of copolymer [1] was used, and an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) 0 A negative electrode was prepared in the same manner as in Example 1, except that 0.35 parts by mass of an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) was used instead of 0.05 parts by mass. The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

(Comparative Example A)
In Example 1, in place of 4.95 parts by mass of copolymer [1], the same procedure as in Example 1 was performed except that only 5.0 parts by mass of copolymer [1] was mixed without adding a cross-linking agent. A negative electrode was produced. The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

(Comparative example 1)
In Example 1, instead of 4.95 parts by mass of copolymer [1], 4.995 parts by mass of copolymer [1] was used, and an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) 0 A negative electrode was prepared in the same manner as in Example 1, except that 0.005 part by mass of an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) was used instead of 0.05 part by mass. The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

(Reference example 1)
In Example 2, instead of 4.95 parts by mass of copolymer [1], 4.5 parts by mass of copolymer [1] was used, and an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) 0 An attempt was made to prepare a negative electrode slurry in the same manner as in Example 1, except that 0.5 parts by mass of an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.) was used instead of 0.05 parts by mass. However, it was difficult to coat the electrodeposited copper foil.

(Examination of cross-linking agent species)
(Example 4)
In Example 2, instead of 0.1 part by mass of the organic titanium compound cross-linking agent (manufactured by Matsumoto Fine Chemical Co., Ltd., TC-400), 0.1 part by mass of the organic titanium compound cross-linking agent (manufactured by Matsumoto Fine Chemical Co., Ltd., TC-300) was added. A negative electrode was produced in the same manner as in Example 2, except that it was used. The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

(Example 5)
In Example 2, instead of 0.1 part by mass of the organic titanium compound cross-linking agent (Matsumoto Fine Chemical Co., Ltd., TC-400), 0.1 part by mass of the organic titanium compound cross-linking agent (Matsumoto Fine Chemical Co., Ltd., TC-315) was added. A negative electrode was produced in the same manner as in Example 2, except that it was used. The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

(Example 6)
In Example 2, instead of 0.1 part by mass of the organic titanium compound cross-linking agent (Matsumoto Fine Chemical Co., Ltd., TC-400), 0.1 part by mass of the organic zirconia compound cross-linking agent (San Nopco Co., Ltd., AZ-Coat 5800MT) was added. A negative electrode was produced in the same manner as in Example 2, except that it was used. The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

(Comparative example 2)
In Example 2, instead of 0.1 part by mass of an organic titanium compound cross-linking agent (TC-400, manufactured by Matsumoto Fine Chemical Co., Ltd.), 0.1 part by mass of an epoxy-based cross-linking agent (Denacol EX-810, manufactured by Nagase Chemtech Co., Ltd.) A negative electrode was produced in the same manner as in Example 2, except for using . The thickness of the active material layer was 50 μm, and the basis weight of the negative electrode was 10 mg/cm ² .

Table 1 summarizes the cross-linking agents used in the above Examples.

Table 2 shows the composition of each negative electrode.

(positive electrode)
(Example A)
Active material (Li (Ni0.8Co0.1Mn0.1) O2: manufactured by Beijing Dangsheng Technology Co., Ltd.) 95 parts by mass, copolymer [1] 3 parts by mass as a binder, acetylene black (Denka black: manufactured by Denka ) and 100 parts by mass of water were mixed to prepare a slurry positive electrode mixture.

After coating and drying the mixture on an aluminum foil having a thickness of 10 μm, the aluminum foil and the coating film are closely bonded by a roll press machine (manufactured by Ohno Roll Co., Ltd.), and then heat treated (under reduced pressure, 120 ° C. , 12 hours or more) to prepare a positive electrode. The positive electrode had a positive electrode capacity density of 1.6 mAh/cm ² (average thickness of the active material layer: 50 μm). In addition, the positive electrode was used as the positive electrode in any of the studies described below.

(Battery assembly)
Using the negative electrodes obtained in Examples 1 to 7, Comparative Examples A and 1 and 2, and the positive electrode obtained in Example A, PP (Celgard #2500: manufactured by Celgard) as a separator, and an electrolytic solution, A small pouch cell of 20 mAh equipped with an EC/DEC (1/1 v/v %) + 1% by mass VC solution (manufactured by Kishida Chemical Co., Ltd.) containing LiPF6 1 mol/L electrolyte was prepared.

PP indicates polypropylene, LiPF6 lithium hexafluorophosphate, EC ethylene carbonate, DEC diethyl carbonate, and VC vinylene carbonate.

<High rate discharge test after aging>
Using the pouch cell produced as described above, a DC-IR resistance value was calculated by conducting aging and high-rate discharge tests according to the procedures shown in (1) to (10) below.
Test temperature: 30°C
Cutoff potential: 2.5-4.3 V (vs. Li+/Li)
(1) In CC (CV) charge/CC discharge, 10 cycles of aging were performed under the conditions of 0.2C (0.05C)/0.2C. At this time, the average discharge voltage value at the end of aging was recorded.
* Described in order of charging/discharging. In brackets is the termination current of CV.
(2) Three cycles were performed under the conditions of 0.2C (0.05C)/0.5C, and the average discharge voltage value at the third cycle was recorded.
(3) Two cycles were performed at 0.2C (0.05C)/0.2C.
(4) The discharge rate in (2) was set to 0.7 C, and 3 cycles were performed, and the average discharge voltage value at the 3rd cycle was recorded.
(5) Two cycles were performed at 0.2C (0.05C)/0.2C.
(6) The discharge rate in (2) was set to 1.0 C and 3 cycles were performed, and the average discharge voltage value at the 3rd cycle was recorded.
(7) Two cycles of 0.2C (0.05C)/0.2C were performed.
(8) The discharge rate of (2) was set to 2.0C, and 3 cycles were performed, and the average discharge voltage value at the 3rd cycle was recorded.
(9) A graph was created in which the horizontal axis represents the discharge current (rate) and the vertical axis represents the average discharge voltage. At that time, the average voltage values at 0.2, 0.5, 0.7, 1.0 and 2.0C were input.
(10) The slope of the graph was taken as the DC-IR value (Ω).
In addition, the test was conducted under these conditions using all the produced pouch cells.
Table 3 shows the DC-IR values calculated by the test.

<Cycle test>
A cycle test was performed in the following procedure using each pouch cell that had been subjected to the high-rate discharge test as described above.
Test temperature: 30°C
Cutoff potential: 2.5-4.3 V (vs. Li+/Li)
Cycle rate: 0.5C (0.05C)/0.5C
Number of cycles: 100
After cycling, the capacity retention rate was calculated using the following formula. Table 3 shows the results.
* Capacity retention rate (%) = [Discharge capacity after 100 cycles (mAh/g)]/[Initial discharge capacity after aging (mAh/g)] x 100

<High rate discharge test after 100 cycles>
A high-rate discharge test was performed using each pouch cell that had undergone the cycle test as described above. The test method and conditions were the same as those of the post-aging high-rate discharge test.
Table 3 shows the DC-IR values calculated by the test.

It can be said that the lower the DC-IR resistance value (Ω), the better the battery performance (discharge characteristics), and the higher the capacity retention rate (%), the better the battery performance (cycle characteristics).

Claims (9)

containing an electrode active material, a cross-linking agent, and a binder;
The binder contains a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product,
the cross-linking agent is a metal chelate complex compound,
0.2 parts by mass or more and less than 10 parts by mass of the cross-linking agent is contained with respect to 100 parts by mass of the total amount of the binder and the cross-linking agent.
Electrode mixture for non-aqueous electrolyte secondary batteries. The electrode mixture for a non-aqueous electrolyte secondary battery according to claim 1, wherein the metal chelate complex compound is at least one selected from the group consisting of titanium chelate complex compounds and zirconium chelate complex compounds. 3. The electrode mixture for a non-aqueous electrolyte secondary battery according to claim 1, wherein said cross-linking agent has two or more functional groups capable of reacting with a carboxyl group and/or a hydroxyl group. 3. The electrode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the cross-linking agent has two or more identical or different functional groups selected from the group consisting of an alkoxy group and an acylate group. Mixture. The non-aqueous electrolyte secondary according to any one of claims 1 to 4, wherein the neutralized alkali metal ethylenically unsaturated carboxylic acid is a neutralized alkali metal acrylate and/or a neutralized alkali metal methacrylate. Electrode mixture for batteries. An electrode for a non-aqueous electrolyte secondary battery using the electrode mixture for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 5. A nonaqueous electrolyte secondary battery comprising the electrode for a nonaqueous electrolyte secondary battery according to claim 6 . An electrical device comprising the non-aqueous electrolyte secondary battery according to claim 7 . mixing an electrode active material, a cross-linking agent, and a binder;
Here, the cross-linking agent is a metal chelate complex compound, the binder is a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and the binder and the cross-linking agent are The cross-linking agent is mixed so that 0.2 parts by mass or more and less than 10 parts by mass with respect to the total amount of 100 parts by mass.
A method for producing an electrode mixture for a non-aqueous electrolyte secondary battery.

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