JP5609616B2 - Conductive protective layer forming paste for current collecting laminates such as non-aqueous secondary batteries - Google Patents

Description

  The present invention relates to a paste for forming a conductive protective layer of a current collecting laminate such as a non-aqueous secondary battery such as a lithium secondary battery or an electric double layer capacitor, a current collecting laminate and an electrode laminate, and further a lithium secondary battery And a non-aqueous secondary battery such as an electric double layer capacitor.

  The lithium secondary battery includes a positive electrode in which a positive electrode mixture layer containing a positive electrode active material such as a lithium-containing composite oxide is provided on a positive electrode current collector such as an aluminum foil, and a negative electrode current collector such as an aluminum foil. A negative electrode mixture layer including a negative electrode active material such as a carbonaceous material, and a nonaqueous electrolytic solution including an electrolyte salt such as a lithium salt and an organic solvent.

  In the lithium secondary battery having such a configuration, there is a problem that the current collector is anodized and corroded due to the action of an electrolyte such as a lithium salt contained in the electrolytic solution, and cycle characteristics and battery capacity are deteriorated. is there.

  In order to prevent or suppress such corrosion of the current collector, Patent Document 1 proposes forming a surface protective layer containing a heterocyclic compound on the current collector. Moreover, in patent document 2, in order to prevent the corrosion of the positive electrode collector (aluminum foil) by the lithium imide salt which is electrolyte salt on a collector, noble metals, alloys, conductive ceramics, semiconductors, organic semiconductors and It has been proposed to form a protective layer containing at least one material selected from conductive polymers. Examples of the conductive polymer include polyaniline, polypyrrole, polyacene, polydisulfide, and polyparaphenylene. One method of forming a protective layer using a conductive polymer is to cast or apply a mixed solution in which a conductive polymer, a binder, and dopan (aromatic sulfonic acid ester) are dissolved in a solvent, and then heat and dry. Illustrated.

  Patent Document 3 describes that a conductive adhesive film is formed by spray-coating a slurry containing carbon black on a current collector (paragraph [0039]).

  Patent Document 4 discloses a positive electrode in which a conductive coating layer is formed on a current collector using polyvinylidene fluoride (PVDF) as a binder, and polytetrafluoroethylene (PTFE) is further formed thereon as a binder. A positive electrode current collector including a positive electrode mixture layer formed by applying a mixture at a specific thickness has excellent high-rate discharge characteristics and charge / discharge cycle characteristics, and has a simple manufacturing process and a large battery capacity. It is described that the next battery is given.

Japanese Patent Laid-Open No. 10-162833 JP 2002-203562 A JP 2008-117574 A JP 2001-351612 A

  However, the conductive protective layer formed by applying a conventional conductive paste does not have sufficient adhesion to the current collector, and in some cases, the electrode may be peeled off from the current collector.

  In particular, the electrode winding method (winding type or spiral type) used as a small and high-capacity lithium secondary battery requires particularly high flexibility, and peeling of the electrode is fatal. It will be something.

  The present invention relates to a conductive protective layer forming paste with improved adhesion between a conductive protective layer and a current collector, a current collector laminate having the conductive protective layer, an electrode, a lithium secondary battery, and an electric secondary battery. An object is to provide a non-aqueous secondary battery such as a multilayer capacitor.

  The present invention relates to a conductive protective layer forming paste for protecting a current collector, comprising a fluororesin dispersion (a) having a functional group having affinity or reactivity with the current collector and a conductive filler (b).

  As the fluororesin of the fluororesin dispersion (a), a structural unit (a1) derived from a fluorine-containing perhaloolefin, a structural unit (a2) derived from a vinyl ether and / or a structural unit (a3) derived from a vinyl ester The fluorine-containing copolymer containing is preferable.

  In addition, the fluororesin of the fluororesin dispersion (a) has a functional group having affinity or reactivity with the current collector other than the structural unit (a2) derived from vinyl ether and the structural unit (a3) derived from vinyl ester. The structural unit (a4) derived from the monomer to have may be included.

  The conductive filler (b) may be a particulate filler, a fibrous filler, or a combination thereof. Preferably, a conductive carbon filler is used.

  The conductive filler (b) is preferably included in an amount of 5 to 300 parts by mass with respect to 100 parts by mass of the fluororesin particles in the fluororesin dispersion (a).

  The fluororesin dispersion (a) may be an aqueous dispersion or an organosol.

  The present invention also relates to a current collecting laminate in which a conductive protective layer (A) obtained by applying the conductive protective layer forming paste of the present invention is provided on a current collector (B).

  The volume resistivity of the conductive protective layer (A) is preferably 0.001 to 50 Ω · cm.

  The present invention also relates to an electrode laminate in which an electrode mixture layer (C) is provided on the conductive protective layer (A) of the current collector laminate of the present invention.

  Furthermore, the present invention also relates to a nonaqueous secondary battery, particularly a lithium secondary battery, or an electric double layer capacitor, comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte, and at least one of the positive electrode and the negative electrode is the electrode laminate of the present invention. Related.

  According to the present invention, a conductive protective layer-forming paste with improved adhesion between the conductive protective layer and the current collector, a current collector laminate having the conductive protective layer, an electrode, a lithium secondary battery, A non-aqueous secondary battery such as an electric double layer capacitor can be provided.

  The conductive protective layer forming paste of the present invention includes a fluororesin dispersion (a) having a functional group having affinity or reactivity with a current collector and a conductive filler (b).

  Hereinafter, each component will be described.

(A) Fluororesin dispersion having functional group having affinity or reactivity with current collector In the present invention, the fluororesin of the fluororesin dispersion (a) has affinity or reactivity with the current collector. Any fluororesin having a functional group may be used, among which a structural unit (a1) derived from a fluorine-containing perhaloolefin, a structural unit (a2) derived from a vinyl ether, and / or a structural unit (a3) derived from a vinyl ester. Further, if necessary, the fluorine-containing copolymer comprising a structural unit (a4) derived from a monomer having a functional group having affinity or reactivity with a current collector different from the structural units (2a) and (a3) Is preferred.

  The structural unit (a1) derived from the fluorine-containing perfluoroolefin has a function of increasing oxidation resistance, and specifically, tetrafluoroethylene (TFE) and chlorotrifluoroethylene (CTFE) having a high fluorine content. The structural unit derived from) can be illustrated preferably.

  When the content of the structural unit (a1) in the fluorine-containing copolymer is increased, the alkali resistance tends to be strong, and when the content is low, the alkali resistance tends to be weak. In this respect, the content ratio of the structural unit (a1) is preferably 25 to 50 mol%, more preferably 30 to 50 mol%, and particularly preferably 40 to 50 mol%.

  The structural unit (a2) derived from vinyl ether and / or the structural unit (a3) derived from vinyl ester is a structural unit having a functional group having affinity or reactivity with the current collector, and adhesion to the current collector. It has a function to improve.

  The structural unit (a2) derived from vinyl ether has improved affinity because the oxygen atom constituting the ether structure has affinity or reactivity with the current collector and is bonded to the metal of the current collector. . In addition, the structural unit (a3) derived from the vinyl ester has improved affinity because the oxygen atom constituting the ester structure has affinity or reactivity with the current collector and binds to the metal of the current collector. I am letting.

  Specific examples of the vinyl ether that gives the structural unit (a2) include one or two types of non-fluorinated vinyl ethers such as ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether; and fluorine-based vinyl ethers such as perfluoro (alkyl vinyl ether). The above can be illustrated.

  Of these, non-fluorinated vinyl ethers or hydroxyl group-containing non-fluorinated vinyl ethers are preferred from the viewpoint of good reactivity and affinity with the metal of the current collector, and particularly hydroxyl-containing non-fluorine-based compounds such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether. Vinyl ether is preferred from the viewpoint of more easily binding to a metal.

  When the content ratio of the structural unit (a2) in the fluorinated copolymer increases, the contact area between the fluorinated copolymer and the current collector tends to increase, and the fluorinated copolymer tends to cover the metal itself. In addition, when the amount is small, the contact area between the fluorine-containing copolymer and the current collector tends to be small. In this respect, the content ratio of the structural unit (a2) is preferably 10 to 30 mol%, more preferably 15 to 30 mol%, and particularly preferably 15 to 27 mol%.

  Specific examples of the vinyl ester that gives the structural unit (a3) include one or more of vinyl benzoate, vinyl acetate, vinyl pivalate, vinyl versatate, and the like.

  Of these, vinyl benzoate, vinyl pivalate, and vinyl versatate are preferable from the viewpoint of good flexibility.

  When the content ratio of the structural unit (a3) in the fluorinated copolymer is increased, the solvent solubility is increased and the battery tends to be dissolved in the electrolyte when the battery is produced. When the content is decreased, the solvent solubility is deteriorated. There is a tendency. In this respect, the content of the structural unit (a3) is preferably 20 to 55 mol%, more preferably 20 to 50 mol%, and particularly preferably 20 to 48 mol%.

  The total content of the structural units (a2) and (a3) in the fluorine-containing copolymer is preferably 45 to 70 mol%, more preferably 50 to 70 mol%, and particularly preferably 55 to 70 mol%.

  The structural unit (a4) having a functional group having affinity or reactivity with the current collector is a structural unit other than the structural units (a2) and (a3). Examples of the functional group having affinity or reactivity with the current collector of the structural unit (a4) include a carboxyl group and its alkyl ester derivative group, a hydroxyl group, an epoxy group, a silicon-containing group, a sulfonic acid group, and a phosphoric acid group. Can be given. In particular, a carboxyl group excellent in affinity or reactivity with the metal constituting the current collector and a silicon-containing group such as an alkyl ester derivative group, a hydroxyl group, and a silyl group are preferable.

  Monomers that give the structural unit (a4) include, for example, monobasic unsaturated carboxylic acids such as acrylic acid, crotonic acid, and vinyl acetic acid and alkyl esters thereof; dibasic unsaturated carboxylic acids such as maleic acid and fumaric acid And monoalkyl esters thereof; 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, Hydroxyl-containing single quantities such as 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, glycerol monoallyl ether Vinyl trimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinylmethyldiethoxysilane, vinyltris (β-methoxyethoxy) silane, trimethoxysilylethyl vinyl ether, triethoxysilyl Ethyl vinyl ether, trimethoxysilylbutyl vinyl ether, methyldimethoxysilylethyl vinyl ether, trimethoxysilylpropyl vinyl ether, triethoxysilylpropyl vinyl ether, vinyltriisopropenyloxysilane, vinylmethyldiisopropenyloxysilane, triisopropenyloxysilylethyl vinyl ether, Triisopropenyloxysilylpropyl vinyl ether, triisopropenyl Luoxysilylbutyl vinyl ether, vinyltris (dimethyliminooxy) silane, vinyltris (methylethyliminooxy) silane, vinylmethylbis (dimethyliminooxy) silane, vinyldimethyl (dimethyliminooxy) silane, tris (dimethyliminooxy) silylethyl Vinyl ether, methylbis (dimethyliminooxy) silylethyl vinyl ether, tris (dimethyliminooxy) silylbutyl vinyl ether, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meta ) Acryloyloxypropylmethyldimethoxysilane, γ- (meth) acryloyloxypropyltriisopropenyloxysilane, γ- (meth) acryloyl Silyl group-containing vinyl monomers such as ruoxypropyltris (β-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltris (dimethyliminooxy) silane, and allyltrimethoxysilane; sulfonic acid groups such as butenesulfonic acid Containing monomer: One or two or more of phosphoric acid group-containing monomers such as mono (2-acryloyloxyethyl) dihydrogen phosphate.

  Of these, monobasic unsaturated carboxylic acid or dibasic unsaturated carboxylic acid and monoalkyl ester thereof are preferable, particularly acrylic acid, from the viewpoint of good hydrogen bonding strength with the hydroxyl group on the metal surface constituting the current collector. And monobasic unsaturated carboxylic acids such as crotonic acid and vinyl acetic acid are preferred.

  When the structural unit (a4) is included, the oxidation resistance may be deteriorated. From this viewpoint, the content ratio of the structural unit (a4) in the fluorine-containing copolymer is preferably 0 to 2 mol%, more preferably 0 to 1 mol%, and particularly preferably 0.5 to 1.0 mol%.

Preferable specific fluorine-containing copolymers include, for example, tetrafluoroethylene / hydroxyethyl vinyl ether / vinyl versatate copolymer, tetrafluoroethylene / hydroxybutyl vinyl ether / vinyl versatate copolymer, tetrafluoroethylene / hydroxy A TFE copolymer comprising structural units (a1), (a2), and (a3) such as butyl vinyl ether / vinyl benzoate / vinyl versatate copolymer;
A CTFE copolymer comprising structural units (a1), (a2) and (a3) such as chlorotrifluoroethylene / hydroxyethyl vinyl ether / vinyl versatate copolymer;
Tetrafluoroethylene / ethyl vinyl ether / maleic acid copolymer, tetrafluoroethylene / ethyl vinyl ether / monoethyl maleate copolymer, tetrafluoroethylene / ethyl vinyl ether / monooleyl maleate copolymer, tetrafluoroethylene / ethyl vinyl ether / fumaric acid A TFE copolymer comprising a structural unit (a1), (a2) and (a4) such as a copolymer, tetrafluoroethylene / ethyl vinyl ether / monoethyl fumarate copolymer;
Tetrafluoroethylene / vinyl acetate / maleic acid copolymer, tetrafluoroethylene / vinyl versatic acid / maleic acid copolymer, tetrafluoroethylene / vinyl pivalate / maleic acid copolymer, tetrafluoroethylene / vinyl acetate / maleic acid Acid monoethyl copolymer, tetrafluoroethylene / vinyl versatate / monoethyl maleate copolymer, tetrafluoroethylene / vinyl pivalate / monoethyl maleate copolymer, tetrafluoroethylene / vinyl acetate / monooleyl maleate copolymer Tetrafluoroethylene / vinyl versatate / monooleyl maleate copolymer, tetrafluoroethylene / vinyl pivalate / monooleyl maleate copolymer, tetrafluoroethylene / vinyl acetate / fumarate Copolymer, tetrafluoroethylene / vinyl versatate / fumaric acid copolymer, tetrafluoroethylene / vinyl pivalate / fumaric acid copolymer, tetrafluoroethylene / vinyl acetate / monoethyl fumarate copolymer, tetrafluoroethylene / Vinyl versatate / monoethyl fumarate copolymer, tetrafluoroethylene / vinyl pivalate / monoethyl fumarate copolymer, tetrafluoroethylene / vinyl acetate / monooleyl fumarate copolymer, tetrafluoroethylene / vinyl versatate A TFE copolymer composed of structural units (a1), (a3) and (a4), such as: / monooleyl fumarate copolymer, tetrafluoroethylene / vinyl pivalate / monooleyl fumarate copolymer;
Tetrafluoroethylene / hydroxyethyl vinyl ether / vinyl benzoate / vinyl versatic acid / crotonic acid copolymer, tetrafluoroethylene / hydroxybutyl vinyl ether / vinyl versatic acid / acrylic acid copolymer, tetrafluoroethylene / hydroxybutyl vinyl ether / Vinyl benzoate / vinyl versatate / acrylic acid copolymer, tetrafluoroethylene / hydroxybutyl vinyl ether / vinyl versatate / vinyl acetate copolymer, tetrafluoroethylene / hydroxybutyl vinyl ether / vinyl benzoate / vinyl versatate / One or more of TFE copolymers comprising structural units (a1), (a2), (a3) and (a4) such as vinyl acetate copolymer.

  The number average molecular weight (Mn) of the fluorinated copolymer used in the present invention is 5,000 to 20,000, preferably 10,000 to 20,000. When the number average molecular weight increases, the solvent solubility tends to decrease, and when it decreases, the weather resistance tends to cause problems.

  Further, the glass transition temperature (Tg) is preferably 10 to 60 ° C., and more preferably 20 to 40 ° C. from the viewpoint of good workability during electrode production.

  As the fluororesin having a functional group having affinity or reactivity with the current collector, one or more of, for example, carboxyl group-containing PVDF and silyl group-containing PVDF may be used in addition to the above-mentioned fluorine-containing copolymer. it can. These fluoropolymers may be used in combination with the above fluorocopolymer.

  The fluororesin dispersion (a) may be an aqueous dispersion or an organosol.

  As the aqueous dispersion, a fluororesin dispersion (dispersion) obtained by emulsion polymerization is preferable. The fluororesin particles in the aqueous dispersion are preferably dispersed as primary particles (average particle size is 0.1 to 0.5 μm).

  When used in an aqueous dispersion, the solvent is water. However, an organic solvent may be added from the viewpoint of improving applicability. Examples of organic solvents include ketones such as methyl ethyl ketone, acetone, cyclohexanone, and dibutyl ketone; amides such as N-methylpyrrolidone, dimethylacetamide, and dimethylformamide; butyl acetate, amyl acetate, butyl propionate, ethyl cellosolve, methyl cellosolve, and the like Examples of such esters include: polar solvents such as ethers such as tetrahydrofuran, diglyme and triglyme; and aromatic solvents such as toluene and xylene. Alcohols and ketones may be used in combination.

  The solid content (fluororesin particle) concentration of the fluororesin aqueous dispersion is preferably 1 to 80% by mass, more preferably about 10 to 70% by mass from the viewpoint of good stability of the aqueous dispersion.

  Examples of the organosol include those obtained by phase-shifting a fluororesin dispersion (dispersion) obtained by emulsion polymerization into an organic solvent. Examples of organic solvents include ketones such as methyl ethyl ketone, acetone, cyclohexanone, and dibutyl ketone; amides such as N-methylpyrrolidone, dimethylacetamide, and dimethylformamide; butyl acetate, amyl acetate, butyl propionate, ethyl cellosolve, methyl cellosolve, and the like Examples of such esters include: polar solvents such as ethers such as tetrahydrofuran, diglyme and triglyme; and aromatic solvents such as toluene and xylene. Alcohols and ketones may be used in combination.

  The solid content (fluororesin particle) concentration of the fluororesin organosol is preferably 1 to 40% by mass, more preferably about 5 to 20% by mass from the viewpoint of good stability.

  In the present invention, in addition to the above fluororesins, other resins, preferably tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyamideimide (PAI), polyimide (PI), polyvinylidene fluoride ( PVDF) and / or tetrafluoroethylene (TFE) -vinylidene fluoride (VDF) copolymer may be included. These other resins can be mixed in the form of an aqueous dispersion or an organosol. When these resins are used in combination, the adhesion with the current collector is further improved. In addition, fluorine or non-fluorine rubber may be used in combination.

  The proportion of the other resin is 300 parts by mass or less, and further 200 parts by mass or less with respect to 100 parts by mass of the fluororesin (solid content).

(B) Conductive filler The conductive filler (b) used in the present invention refers to a filler having a volume resistivity of 1 × 10 ⁻⁹ to 1 Ω · cm. A preferred volume resistivity is 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ Ω · cm.

  Examples of the conductive filler (b) include a conductive carbon filler. Moreover, although a conductive metal filler can be used, it is desirable to use the conductive metal filler in combination with a conductive carbon filler. Examples of the conductive metal filler include titanic acid and silicon oxide.

  These conductive fillers may be particulate fillers, fibrous fillers, or combinations thereof.

  Examples of the particulate carbon filler include ketjen black, acetylene black, nanoporous carbon, graphite (natural graphite, artificial graphite), furnace black, channel black, etc. Among them, the chemical resistance and conductivity are good, and the composition From the viewpoint of good fluidity, nanoporous carbon and graphite are preferred, and from the viewpoint of good chemical resistance and electrical conductivity, ketjen black and acetylene black are preferred. The average primary particle diameter is preferably 0.02 to 50 nm, and more preferably 0.025 to 40 nm from the viewpoint of good conductivity.

  Examples of fibrous carbon fillers include carbon fibers, carbon nanotubes, and carbon nanofibers. Among them, carbon nanotubes and carbon nanofibers are preferable because of their good conductivity, and carbon fibers, particularly produced by a gas phase method. The carbon fiber obtained is preferable from the viewpoint of good cost performance. The fibrous carbon has an average fiber diameter of 500 nm or less, preferably 0.1 to 200 nm, and more preferably 1 to 200 nm from the viewpoint of good conductivity. Further, the ratio of average fiber length / average fiber diameter is preferably 5 or more, and more preferably 10 or more from the viewpoint of good conductivity. Moreover, it is preferable that it is 1000 or less, Furthermore, 500 or less from the point which preparation of a composition is easy.

  In particular, the filler to be blended is preferably a filler that is at least one selected from the group consisting of ketjen black, acetylene black, nanoporous carbon, graphite, carbon fiber, carbon nanotube, and carbon nanofiber.

  The particulate carbon filler and the fibrous carbon filler may be used in combination. When used in combination, for example, the conductivity aspect ratio of the protective film can be further easily controlled, and the conductivity of the protective film can be further improved as compared with the single use. The mixing ratio (mass ratio) of the particulate carbon filler / fibrous carbon filler is preferably 10/90 or more, and more preferably 20/80 or more from the viewpoint of giving good fluidity to the composition. Further, it is preferably 90/10 or less, and more preferably 80/20 or less from the viewpoint of easy control of the conductive aspect ratio in the protective film.

  The compounding quantity of an electroconductive filler (b) is 5-300 mass parts with respect to 100 mass parts of functional group containing fluororesin (solid content) (a). When less than 5 mass parts, the electroconductivity of a protective film becomes inadequate and is unpreferable. On the other hand, when the amount exceeds 300 parts by mass, the preparation of the composition becomes difficult, which is not preferable. A preferred lower limit is 5 parts by mass from the viewpoint of good conductivity of the protective film. A preferable upper limit is 200 parts by mass from the viewpoint of good stability during molding, and 100 parts by mass from the viewpoint of easy preparation of the composition. Within this range, a conductive carbon filler and a metal filler may be used in combination. These combinations are particulate carbon filler and particulate and / or fibrous metal filler, fibrous carbon filler and particulate and / or fibrous metal filler, and are appropriately selected according to the required performance. . The mixing ratio may be appropriately selected in consideration of the degree and weight of conductivity of each filler, the elasticity and flexibility of the generated conductive layer, and the like.

  In addition to or in place of the conductive filler (b), a nonconductive filler (volume resistivity exceeds 1 Ω · cm) may be used in combination. Examples of the nonconductive filler include a nonconductive carbon filler, a nonconductive inorganic oxide filler, and a nonconductive resin filler. Specifically, non-conductive carbon black, non-conductive Austin black, non-conductive graphite (natural graphite, artificial graphite), non-conductive carbon nanotube, non-conductive graphitized carbon black, etc. Carbon filler: non-conductive such as silica, silicate, clay, diatomaceous earth, montmorillonite, talc, calcium carbonate, calcium silicate, barium sulfate, fatty acid calcium, titanium oxide, bengara, boron nitride, aluminum nitride, magnesium oxide, alumina Inorganic oxide filler; polyethylene, heat-resistant engineering plastics, PTFE-based tetrafluoroethylene and ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), etc. Rimmer (although the functional group-containing fluorine resin (a) is excluded), such as a non-conductive resin filler such as polyimide and the like. The blending amount may be appropriately selected in consideration of the effect of blending and the degree and weight of conductivity of the conductive filler (b), the elasticity and flexibility of the generated conductive layer, and the like.

(C) Other components The conductive paste of the present invention is prepared by adding a conductive filler (b) to a functional group-containing fluororesin dispersion (a).

  In the present invention, the blending ratio of the functional group-containing fluororesin (solid content) (a) and the conductive filler (b) is the ratio described in the protective layer. Moreover, the quantity of a solvent should just be an quantity used as the density | concentration suitable for coating.

  In the conductive protective layer-forming paste of the present invention, a processing aid and an adhesive (silane coupling agent, epoxy, phenol resin) that cures by crosslinking are further used unless the object of the present invention is impaired. Also good.

  Preparation of the conductive protective layer-forming paste of the present invention may be achieved by mixing the components by an ordinary mixing method.

  The conductive protective layer (A) in the present invention is formed by applying the conductive protective layer forming paste of the present invention to the current collector (B) to constitute a current collector laminate.

  A conventionally well-known method may be sufficient as the formation method of an electroconductive protective layer (A). For example, apply to the current collector by roller coating, brush coating, dip coating, spray coating, gravure coating, coil coating, curtain flow coating, etc., and let it dry naturally or heat at ambient temperature To form a protective layer.

  The conductive protective layer (A) thus obtained can control the volume resistivity in the range of 0.001 to 50 Ω · cm, and if necessary, 0.001 to 10 Ω · cm, further 1 Ω · cm or less. A highly conductive protective layer can be provided.

  The thickness of the conductive protective layer may be appropriately selected in the range of 0.5 to 50 μm. For example, from the viewpoint of reducing resistance, it is 0.5 μm or more, more preferably 1.0 μm or more. To 50 μm or less, more preferably 10 μm or less.

  Next, the current collector will be described.

  The present invention is particularly effective for a material that is corroded by a lithium salt in an electrolytic solution. As a material constituting such a current collector, for example, aluminum or an alloy thereof, stainless steel, nickel or an alloy thereof, titanium or an alloy thereof, a material obtained by treating carbon or titanium on the surface of aluminum or stainless steel, or the like is used. Among these, aluminum and aluminum alloys are mentioned as current collectors that are particularly protected. These materials can also be used after oxidizing the surface. Further, it is preferable that the surface of the current collector is roughened to improve the adhesion. The thickness of the current collector is usually in the range of 5 to 30 μm.

  The current collecting laminate of the present invention may be used for a positive electrode or a negative electrode. In particular, a great effect is exhibited when used for a positive electrode in which the current collector is severely corroded.

  The present invention also relates to an electrode laminate in which an electrode mixture layer (C) is provided on the conductive protective layer (A) of the current collector laminate of the present invention.

  The electrode mixture forming the electrode mixture layer (C) contains an electrode active material and a binder, and if necessary, is prepared by blending other materials. In the present invention, a conventionally known positive electrode mixture and negative electrode mixture can be used, but an electrode mixture having a high voltage specification is particularly effective.

The positive electrode active material is particularly preferably a lithium-containing transition metal composite oxide that produces a high voltage. For example, the formula (1): Li _a Mn _2-b M ¹ _b O ₄ (where 0.9 ≦ a; 0 ≦ b ≦ 1.5; M ¹ is selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si and Ge Lithium manganese spinel composite oxide represented by the formula (2): LiNi _1-c M ² _c O ₂ (where 0 ≦ c ≦ 0.5; M ² is Fe, Lithium represented by at least one metal selected from the group consisting of Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge) nickel composite oxide, or LiCo in ^{_{1-d M 3 d O 2}} ( wherein, 0 ≦ d ≦ 0.5; M 3 At least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge) Lithium-cobalt composite oxide is preferable.

Specifically, LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , or LiNi _1/3 Co _1/3 Mn _1/3 O ₂ has an energy density. It is preferable in that a high and high output lithium secondary battery can be provided.

In addition, a positive electrode active material such as LiFePO ₄ , LiNi _0.8 Co _0.2 O ₂ , Li _1.2 Fe _0.4 Mn _0.4 O ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiV ₃ O ₆ may be used.

  The compounding amount of the positive electrode active material is preferably 50 to 99% by mass, more preferably 80 to 99% by mass of the positive electrode mixture, from the viewpoint of high battery capacity.

Examples of the negative electrode active material include carbon materials, and also include metal oxides and metal nitrides capable of inserting lithium ions. Examples of carbon materials include natural graphite, artificial graphite, pyrolytic carbons, cokes, mesocarbon microbeads, carbon fibers, activated carbon, and pitch-coated graphite. Metal oxides capable of inserting lithium ions include tin and Examples of the metal compound include silicon and titanium, such as tin oxide, silicon oxide, and lithium titanate. Examples of the metal nitride include Li _2.6 Co _0.4 N.

  The compounding amount of the negative electrode active material is preferably 50 to 99% by mass, more preferably 80 to 99% by mass of the negative electrode mixture, from the viewpoint of high battery capacity.

  Examples of the binder include fluorine resin, non-fluorine resin, rubber and the like.

  Examples of the fluororesin include PTFE and PVDF. PTFE may be a homopolymer of tetrafluoroethylene, or modified PTFE in which a small amount of other monomers such as hexafluoropropylene (HFP) and perfluoro (alkyl vinyl ether) (PAVE) are copolymerized. Also good.

  Examples of non-fluorinated resins include polyacrylic acid. Examples of the rubber include ethylene / propylene / diene copolymer rubber (EPDM) and styrene / butadiene copolymer rubber (SBR).

  The blending amount of the binder is preferably 0.5 to 15% by mass, more preferably 0.5 to 10% by mass of the electrode mixture from the viewpoint of high battery capacity.

  Other components include fluorine resins such as TFE / HFP copolymer resins and ETFE and VdF copolymer resins for improving the adhesion of electrode mixtures and for improving the utilization of active materials; Fluororubber and acrylic rubber for improving; Cellulosic resin such as cellulose acetate for improving withstand voltage; Additives used for manufacturing electrodes of lithium secondary batteries, such as conductive materials, thickeners, other heavy metals Examples include coalescence and surfactant. Examples of the conductive material include conductive carbon black such as acetylene black and ketjen black; and carbonaceous materials such as graphite and carbon fiber.

  When these components are required, the electrode mixture layer (C) is formed by appropriately mixing using an appropriate solvent, preparing a composition for forming an electrode mixture as a uniform mixture, and conducting the current collecting laminate. It can carry out by methods, such as a spin coat, a blade coat, a roll coat, and a dip coat, on a protective layer (A).

  The electrode subjected to the drying treatment is usually further subjected to a rolling treatment, if necessary, and then cut and processed into a predetermined thickness and size to obtain an electrode for a lithium secondary battery. The rolling process and the cutting process may be ordinary methods.

  In the electrode laminate of the present invention, since the current collector is protected from the lithium salt in the electrolytic solution by the protective layer using PTFE as the binder, corrosion of the current collector can be suppressed even at a high operating voltage, cycle characteristics, etc. The deterioration of battery characteristics can be suppressed.

  The present invention also relates to a non-aqueous secondary battery, particularly a lithium secondary battery. The lithium secondary battery of the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, and uses the electrode laminate of the present invention as the positive electrode and / or the negative electrode.

  In addition, when using electrodes other than the electrode of this invention for one of a positive electrode or a negative electrode, those positive electrodes or negative electrodes can use a conventionally well-known electrode. However, it is preferable to use the electrode of the present invention for the positive electrode, which has a large flexibility problem.

  The non-aqueous electrolyte is not particularly limited as long as it is an electrolyte containing an electrolyte salt and an organic solvent for dissolving the electrolyte salt and is used in a lithium secondary battery.

Examples of the electrolyte include known electrolyte salts such as LiPF ₆ , LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) _2. Examples of the organic solvent include ethylene carbonate and dimethyl Hydrocarbon solvents such as carbonate, methyl ethyl carbonate, diethyl carbonate, propylene carbonate; fluorine solvents such as HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H, CF ₃ COOCF ₃ , CF ₃ COOCH ₂ CF ₃ , and mixtures thereof Although a solvent etc. can be illustrated, it is not limited only to these.

  A separator may be disposed in the lithium secondary battery of the present invention. There is no restriction | limiting in particular as a separator, A microporous polyethylene film, a microporous polypropylene film, a microporous ethylene propylene copolymer film, a microporous polypropylene / polyethylene two-layer film, a microporous polypropylene / polyethylene / polypropylene three-layer film Etc. In addition, a film in which an aramid resin is coated on a separator made for the purpose of improving safety such as a short circuit caused by Li dentrite, or a film in which a resin containing polyamideimide and an alumina filler is coated on a separator can be given (for example, JP, 2007-299612, A, JP, 2007-324073, A).

  The lithium secondary battery of the present invention is useful as a large-sized lithium secondary battery for a hybrid vehicle or a distributed power source, a small-sized lithium secondary battery such as a mobile phone or a personal digital assistant.

  The present invention also relates to an electric double layer capacitor using the electrode of the present invention. The basic structure of the electric double layer capacitor is the same as the conventional one except that the electrode of the present invention is used as the electrode.

  EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

  The measurement method and evaluation method employed in the present invention are as follows.

(Film thickness measurement)
It measures using quick macro MDQ-30M made from Mitutoyo Corporation.

(Measurement of volume resistivity)
The volume resistivity is measured by the 4-terminal method using Loresta-GP manufactured by Mitsubishi Chemical Analytech Co., Ltd.

(Adhesiveness between current collector and conductive protective layer)
A conductive protective layer is applied to one surface of an aluminum foil having a thickness of 15 μm so as to have a thickness of 5 μm. The electrode was cut into a width of 2.0 cm and a length of 10 cm, cellophane tape (manufactured by Nichiban Co., Ltd., registered trademark) was attached to the electrode surface, the electrode was fixed, and the tape was applied to 50 mm / min according to JISK6854-2. The strength (N / cm) when peeled in the 180 ° direction at a speed is measured five times, and the adhesiveness is evaluated from the average value.

Synthesis Example 1 (Synthesis of fluorinated copolymer)
A stainless steel autoclave with a capacity of 6000 ml was charged with 2891 g of butyl acetate, 638.0 g of versatile vinyl acid (VV9) consisting of 9 carbon atoms, 156.7 g of 4-hydroxybutyl vinyl ether (HBVE), and cooled to 5 ° C. The operation of substituting with nitrogen under reduced pressure was repeated three times. Finally, the pressure was reduced again to charge 481.7 g of tetrafluoroethylene. The temperature was raised to 65.0 ° C. with stirring, and 12.5 g of a peroxide polymerization initiator (Perroyl 355 manufactured by NOF Corporation) was charged to initiate polymerization. At the same time, a mixture of 639.0 g of VV9 and 156.7 g of HBVE was continuously charged over 1.5 hours. At that temperature, an initiator was charged and reacted for 3 hours, and an additional 12.5 g of a polymerization initiator (Perroyl 355) was charged. Further the temperature was 4 hours, the reactor internal pressure to stop the reaction at the time when decreased from 1.4MPaG (14.5kgf / cm ² G) to ^{0.2MPaG (2.1kgf / cm 2 G)} , hydroxyl group-containing An aqueous dispersion of a fluorinated copolymer was obtained. The polymerization yield was 92.3%. The obtained fluorine-containing copolymer was analyzed by ¹⁹ F-NMR, ¹ H-NMR and elemental analysis. As a result, it was found that the fluorine-containing copolymer was 45 mol% tetrafluoroethylene, 39 mol% VV9 and 16 mol% HBVE. The copolymer had a number average molecular weight (Mn) of 1.5 × 10 ⁴ and a glass transition temperature (Tg) of 35 ° C.

Synthesis Examples 2-8
An aqueous dispersion of a hydroxyl group-containing fluorine-containing copolymer was obtained in the same manner as in Example 1 except that the monomers listed in Table 1 were used for copolymerization. Table 1 shows the composition (mol%), number average molecular weight (Mn), and glass transition temperature (Tg) of the resulting fluorinated copolymer.

In addition, the symbol of the monomer of Table 1 is the following compounds.
TFE: Tetrafluoroethylene CTFE: Chlorotrifluoroethylene HBVE: 4-hydroxybutyl vinyl ether HEVE: 4-hydroxyethyl vinyl ether VBz: Vinyl benzoate VV9: Vinyl ester of aliphatic carboxylic acid having 9 carbon atoms (Beoba manufactured by Shell Chemical Co., Ltd.) 9)
CA: Crotonic acid VA: Vinyl acetate

Example 1
50 g of acetylene black (average particle size 35 nm) as the conductive filler (b) was increased to 100 g of the hydroxyl group-containing fluorine-containing copolymer aqueous dispersion obtained in Synthesis Example 1 (adjusted to a solid content concentration of 20% by mass). 2 g of acrylic resin (A10H manufactured by Toa Gosei Co., Ltd.) was added as a sticking agent to prepare a conductive protective layer forming paste. Next, this paste was uniformly applied on the positive electrode current collector (aluminum foil having a thickness of 15 μm) to form a conductive fluorine-containing resin layer (thickness of 5 μm) on one surface, and heated at 80 ° C. with a hot air dryer at 10 ° C. After drying for a minute, pressing was performed to form a conductive fluorine-containing resin layer (total thickness: 10 μm) on one side. Next, after evacuating with a vacuum dryer, drying was performed at 120 ° C. for 1 hour to prepare a positive electrode current collector laminate having a conductive protective layer formed on one side. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Examples 2-8
Applied to positive electrode current collector (15 μm thick aluminum foil) in the same manner as in Example 1 except that the hydroxyl group-containing fluorine-containing copolymers obtained in Synthesis Examples 2 to 8 were used as the fluororesin (a). Then, a positive electrode current-collecting laminate having a conductive protective layer formed on one side was produced. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 9
The hydroxyl group-containing fluorine-containing copolymer obtained in Synthesis Example 1 and FEP aqueous dispersion (ND110 manufactured by Daikin Industries, Ltd.) are mixed at a solid content ratio of 6/4 to obtain a fluororesin aqueous dispersion (solid content concentration 20). 100 g) was prepared. Into this aqueous dispersion, 50 g of acetylene black (average particle size 35 nm) as a conductive filler (b) and 1 g of carboxymethyl cellulose (CMC) as a thickener were added to prepare a conductive protective layer forming paste. Next, this paste was uniformly applied on the positive electrode current collector (aluminum foil having a thickness of 15 μm) to form a conductive fluorine-containing resin layer (thickness of 5 μm) on one surface, and heated at 80 ° C. with a hot air dryer at 10 ° C. After drying for a minute, pressing was performed to form a conductive fluorine-containing resin layer (total thickness: 10 μm) on one side. Next, after vacuuming with a vacuum dryer, drying was performed at 250 ° C. for 10 hours to produce a positive electrode current collector laminate having a conductive protective layer formed on one side. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 10
The hydroxyl group-containing fluorine-containing copolymer obtained in Synthesis Example 1 and FEP aqueous dispersion (ND110 manufactured by Daikin Industries, Ltd.) are mixed at a solid content ratio of 6/4, and then converted to methyl isobutyl ketone (MIBK). In addition, 100 g of an organosol adjusted to a solid content concentration of 20% by mass was prepared. 50 g of acetylene black (average particle size 35 nm) as the conductive filler (b) was added thereto to prepare a conductive protective layer forming paste. Next, this paste was uniformly applied on the positive electrode current collector (aluminum foil having a thickness of 15 μm) to form a conductive fluorine-containing resin layer (thickness of 5 μm) on one surface, and heated at 80 ° C. with a hot air dryer at 10 ° C. After drying for a minute, pressing was performed to form a conductive fluorine-containing resin layer (total thickness: 10 μm) on one side. Next, after vacuuming with a vacuum dryer, drying was performed at 250 ° C. for 10 hours to produce a positive electrode current collector laminate having a conductive protective layer formed on one side. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 11
In Example 9, a conductive protective layer forming paste was prepared in the same manner except that ketjen black was used instead of acetylene black, and a positive electrode current collector (15 μm thick aluminum) was prepared in the same manner as in Example 9. The positive electrode current-collecting laminated body in which the electroconductive protective layer was formed in the single side | surface was produced. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 12
A conductive protective layer was prepared in the same manner as in Example 9 except that vapor grown carbon fiber (average fiber diameter: 100 nm, fiber length: 10 μm, VGCF @ manufactured by Showa Denko KK) was used instead of acetylene black. A forming paste was prepared, applied to a positive electrode current collector (a 15 μm thick aluminum foil) and dried in the same manner as in Example 9 to produce a positive electrode current collector laminate having a conductive protective layer formed on one side. . About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 13
A conductive protective layer forming paste was prepared in the same manner as in Example 9, except that the amount of acetylene black was changed to 150 g. A positive electrode current collector (a 15 μm thick aluminum foil) was prepared in the same manner as in Example 9. ) And dried to prepare a positive electrode current collector laminate having a conductive protective layer formed on one side. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 14
In Example 9, a conductive protective layer forming paste was prepared in the same manner except that the amount of acetylene black was changed to 2.5 g, and a positive electrode current collector (thickness of 15 μm) was prepared in the same manner as in Example 9. The positive electrode current-collecting laminated body in which the electroconductive protective layer was formed in the single side | surface was produced. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 15
The hydroxyl group-containing fluorine-containing copolymer obtained in Synthesis Example 1 and a TFE / VDF copolymer aqueous dispersion (VT470 manufactured by Daikin Industries, Ltd.) were mixed at a solid content ratio of 6/4, and then methyl isobutyl ketone. 100 g of an organosol which was phase-inverted to (MIBK) and further adjusted to a solid content concentration of 20% by mass was prepared. 50 g of acetylene black (average particle size 35 nm) as the conductive filler (b) was added thereto to prepare a conductive protective layer forming paste. Next, this paste was uniformly applied on the positive electrode current collector (aluminum foil having a thickness of 15 μm) to form a conductive fluorine-containing resin layer (thickness of 5 μm) on one surface, and heated at 80 ° C. with a hot air dryer at 10 ° C. After drying for a minute, pressing was performed to form a conductive fluorine-containing resin layer (total thickness: 10 μm) on one side. Next, after vacuuming with a vacuum dryer, drying was performed at 250 ° C. for 10 hours to produce a positive electrode current collector laminate having a conductive protective layer formed on one side. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 16
The hydroxyl group-containing fluorine-containing copolymer obtained in Synthesis Example 1 and a TFE / VDF copolymer aqueous dispersion (VT470 manufactured by Daikin Industries, Ltd.) were mixed at a solid content ratio of 8/2, and then N-methyl 100 g of an organosol which was phase-inverted to pyrrolidone (NMP) and further adjusted to a solid content concentration of 20% by mass was prepared. 50 g of acetylene black (average particle size 35 nm) as the conductive filler (b) was added thereto to prepare a conductive protective layer forming paste. Next, this paste was uniformly applied on the positive electrode current collector (aluminum foil having a thickness of 15 μm) to form a conductive fluorine-containing resin layer (thickness of 5 μm) on one surface, and heated at 80 ° C. with a hot air dryer at 10 ° C. After drying for a minute, pressing was performed to form a conductive fluorine-containing resin layer (total thickness: 10 μm) on one side. Next, after vacuuming with a vacuum dryer, drying was performed at 250 ° C. for 10 hours to produce a positive electrode current collector laminate having a conductive protective layer formed on one side. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 17
In Example 1, a positive electrode current collector laminate in which a conductive protective layer was formed on one side was prepared in the same manner except that a thin steel plate (15 μm thick) was used instead of the aluminum foil as the current collector. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Example 18
In Example 1, a positive electrode current collector laminate in which a conductive protective layer was formed on one side was prepared in the same manner except that a copper foil (15 mm thickness) was used instead of the aluminum foil as the current collector. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

Reference example 1
In Example 1, a similar method was used except that PVDF having no functional group (made by Kureha Chemical Co., Ltd., trade name: KF-7200) was used instead of the hydroxyl group-containing fluorine-containing copolymer obtained in Synthesis Example 1. A conductive protective layer forming paste was prepared, applied to a positive electrode current collector (aluminum foil having a thickness of 15 μm) and dried in the same manner as in Example 1, and a positive electrode current collector having a conductive protective layer formed on one side. A laminate was produced. About the obtained positive electrode current collection laminated body, the adhesiveness and volume resistivity of a collector and a conductive protective layer were measured. The results are shown in Table 2.

  From Table 2, the conductive protective layer of the laminated current collector obtained in the example is firmly bonded to the current collector, and all except for Reference Example 1 have a high conductive protection of 1.0 Ω / cm or less. You can see that it is layered.

Example 19
LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , carbon black and PVDF (manufactured by Kureha Chemical Co., Ltd., trade name: KF-1000) were formed on the positive electrode current-collecting laminate of the present invention produced in Example 1. The positive electrode active material mixed in 90/3/7 (mass% ratio) was dispersed in N-methyl-2-pyrrolidone to uniformly apply a positive electrode material mixture slurry and dried to obtain a positive electrode material mixture layer ( A thickness of 50 μm) was formed, and then compression molding was performed with a roller press to produce a positive electrode laminate.

  Using the obtained positive electrode laminate, a coin-type lithium secondary battery was produced in the following manner, and the discharge capacity and cycle characteristics were examined. The results are shown in Table 3.

(Production of coin-type battery)
The positive electrode laminate is punched into a diameter of 1.6 mm with a punching machine to produce a circular positive electrode.

  Separately, styrene-butadiene rubber dispersed with distilled water was added to artificial graphite powder so as to have a solid content of 6% by mass, and mixed with a disperser to form a slurry. A negative electrode current collector (thickness 10 μm) On the copper foil) and dried to form a negative electrode mixture layer, followed by compression molding with a roller press machine, and punched into a diameter of 1.6 mm with a punching machine to produce a circular negative electrode To do.

The above-mentioned circular positive electrode is opposed to the positive electrode and the negative electrode with a microporous polyethylene film (separator) having a thickness of 20 μm, and an electrolytic solution (EC / MEC = 30/70 vol% electrolyte salt dissolving solvent is LiPF _6. Is added to a concentration of 1.0 mol / liter), and after the electrolyte has sufficiently penetrated the separator, etc., it is sealed, precharged and aged, and then a coin-type lithium secondary A battery is produced.

(Measurement of battery characteristics)
The discharge capacity and cycle characteristics of the coin-type lithium secondary battery were examined as follows.

(Discharge capacity)
When the charge / discharge current is indicated by C, measurement is performed under the following charge / discharge measurement conditions with 5 mA as 1C. The evaluation is performed using an index with the result of the discharge capacity of Reference Example 1 as 100.

Charging / discharging conditions Charging: Holds until the charging current becomes 1 / 10C at 1.0C, 4.7V (CC / CV charging)
Discharge: 1C 3.0Vcut (CC discharge)

Examples 20 to 35 and Reference Example 2
A positive electrode laminate and a coin-type lithium secondary battery were produced in the same manner as in Example 19 except that the positive electrode current collectors of Examples 2 to 17 and Reference Example 1 were used. (Discharge capacity) was examined. The results are shown in Table 3.

  From Table 3, it can be seen that the discharge capacity of all the electrodes of the Examples is higher than that of Reference Example 2 because the resistance is small due to the influence of the conductive protective layer. Therefore, it turns out that there exists an effect rather than apply | coating a conductive protective layer to a collector.

Example 36
(Electric double layer capacitor)
50 g of acetylene black (average particle size 35 nm) as the conductive filler (b) was increased to 100 g of the hydroxyl group-containing fluorine-containing copolymer aqueous dispersion obtained in Synthesis Example 1 (adjusted to a solid content concentration of 20% by mass). 2 g of acrylic resin (A10H manufactured by Toa Gosei Co., Ltd.) was added as a sticking agent to prepare a conductive protective layer forming paste. Next, this paste was uniformly applied onto an edged aluminum (product number: 20CB, thickness: about 20 μm) manufactured by Nippon Electric Power Storage Co., Ltd., and a conductive fluorine-containing resin layer (thickness: 7 μm) was formed on both sides. It dried for 10 minutes at 80 degreeC with the hot air dryer. Next, after drawing a vacuum with a vacuum dryer, drying was performed at 120 ° C. for 1 hour to prepare a current collecting laminate.

8 parts by mass of PVDF, 100 parts by mass of activated carbon (product number: RP20, surface area: 1700 m ² / g) manufactured by Kuraray Chemical Co., Ltd., 3 parts by mass of Denka Black (conducting aid) manufactured by Denki Kagaku Kogyo Co., Ltd. 12 parts by mass of Ketjen Black manufactured by Lion Co., Ltd. was mixed to produce a mixture slurry for electrodes.

Conductive layer double-sided coating Both sides of the etched aluminum were coated on the both sides of the electrode mixture slurry (positive electrode 103 μm, negative electrode 80 μm) to form an electrode mixture (activated carbon) layer to produce an electrode. The density of the obtained electrode mixture layer was 0.52 g / cm ³ . Hereinafter, the current collector, the conductive layer, and the electrode mixture layer are collectively referred to as an electrode.

Example 37
(Production of diameter 18φ wound body)
The electrode 1 of Example 36 and Reference Example 3 produced above was cut to a width of 30 mm, and this electrode and a TF45-30 (separator) made by Nippon Kogyo Paper Industries Co., Ltd. cut to a width of 34 mm were wound together for EDLC. Winded by machine. At that time, a tab lead for electrode drawing was connected by caulking to the electrode to produce a cylindrical wound body having a diameter of 16 mm.

(Preparation of electrolyte)
Sulfolane, HCF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H and dimethyl carbonate were mixed at a volume ratio of 65/15/20 to prepare an electrolyte salt dissolving solvent. When triethylmethylammonium tetrafluoroborate (TEMA · BF ₄ ) was added to the electrolyte salt dissolving solvent so as to have a concentration of 1.2 mol / liter, it was uniformly dissolved.

(Production of φ18 wound cell)
After the cylindrical winding body, cylindrical aluminum case, and rubber packing are vacuum dried, the cylindrical winding body is inserted into the cylindrical aluminum case in a dry chamber, and then the electrolyte is injected and sealed through the rubber packing. Thus, a wound cell (φ18 mm × 40 mm) was produced. The produced wound cell was measured for internal resistance by the following method and found to be 10.5 mΩ.

(Measurement of internal resistance)
The electric double layer capacitor starts to be charged with a constant current of 500 mA. When a predetermined charging voltage is reached, the voltage is maintained to be constant voltage charging, and charging is completed when constant voltage charging is performed for 5 minutes. Next, immediately after the end of charging, discharging is performed at a constant current of 15 mA until reaching 0V. This charging / discharging operation is performed for 3 cycles, and the internal resistance is calculated by the relationship of R = ΔV / I from the voltage value 0.1 seconds after the end of the third cycle discharge.

Reference example 3
The electrode mixture slurry prepared in Example 36 was directly applied to both sides of the etched aluminum used in Example 36 without applying a conductive layer (positive electrode 96 μm, negative electrode 73 μm) to form an electrode mixture (activated carbon) layer. Then, an electrode was produced. The density of the obtained electrode mixture layer was 0.52 g / cm ³ as in Example 36.

  A φ18 wound cell was prepared in the same manner as in Example 36 except that the obtained electrode was used, and the internal resistance was measured and found to be 12.2 mΩ.

  The results of Example 36 and Reference Example 3 indicate that the electrode of Example 36 has a lower resistance than Reference Example 3 due to the influence of the conductive protective layer, and the conductive protective layer is applied to the current collector. It can be seen that this is effective in improving the characteristics of the electric double layer capacitor.

Claims (12)

Look containing a fluorine resin dispersion (a) a conductive filler (b) having a functional group having a current collector and affinity or reactivity,
The fluororesin of the fluororesin dispersion (a) is derived from a structural unit (a1) derived from a fluorine-containing perhaloolefin, a structural unit (a2) derived from a hydroxyl group-containing non-fluorinated vinyl ether, and / or a vinyl ester. A conductive protective layer forming paste for protecting a current collector, which is a fluorine-containing copolymer containing the structural unit (a3) . The fluororesin of the fluororesin dispersion (a) has a functional group having affinity or reactivity with the current collector other than the structural unit (a2) derived from vinyl ether and the structural unit (a3) derived from vinyl ester. claim 1, wherein the conductive protective layer forming paste containing a structural unit (a4) derived from a monomer. The conductive filler (b) is a particulate filler, a fibrous filler or a combination thereof in which claim 1 or 2 electroconductive protective layer forming paste according to. The conductive protective layer forming paste according to any one of claims 1 to 3 , wherein the conductive filler (b) is a conductive carbon filler. The conductive filler (b) is contained in an amount of 5 to 300 parts by mass with respect to 100 parts by mass of the fluororesin having a functional group (solid content) in the fluororesin dispersion (a) having the functional group. 5. The conductive protective layer forming paste according to any one of 4 above. The fluorine resin dispersion (a) is, according to claim 1 to 5 in any one of the description of the conductive protective layer forming paste is an aqueous dispersion. The conductive protective layer forming paste according to any one of claims 1 to 5 , wherein the fluororesin dispersion (a) is an organosol. Collector laminate claims 1-7 electroconductive protective layer forming paste applied conductive protective layer obtained according to any one of (A) is provided on the collector (B) . The current collecting laminate according to claim 8, wherein the conductive protective layer (A) has a volume resistivity of 0.001 to 50 Ω · cm. The electrode laminated body by which an electrode mixture layer (C) is provided on the electroconductive protective layer (A) of the current collection laminated body of Claim 8 or 9 . A lithium secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein at least one of the positive electrode and the negative electrode is the electrode laminate according to claim 10 . An electric double layer capacitor comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein at least one of the positive electrode and the negative electrode is an electrode laminate according to claim 10 .