JP2001015104A - Manufacture of electrode member and manufacture of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for an electrode member with reduced warp and excellent flatness formed with an active material layer containing an active material and a binder on a current collecting body. SOLUTION: In this manufacturing method for an electrode member formed with an active material layer containing an active material and a binder on a current collecting body, the active material layer is formed and then the electrode member is heat treated in a condition where tension and/or pressure are applied. The active material layer is formed by being dried after a coating containing an active material and a binder is coated on the current collecting body, or after the active material is formed, calendering treatment is applied and then heat treatment is applied. The electrode member is held in a substantially plate-like configuration and is heat treated, or after the electrode member is wound in a roll-like configuration, the electrode member is heated while running in a condition where tension is applied by a running system having a winding and unwinding mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an electrode member and a method for manufacturing a battery. More specifically, the present invention provides a method for producing an electrode member which is formed by forming an active material layer containing an active material and a binder on a current collector, has less warpage, and is excellent in flatness, and a method for making an electrolyte non-fluidized. The present invention relates to a method for manufacturing a battery suitable for a flat battery. The present invention is particularly suitable for producing a lithium secondary battery using a gel electrolyte obtained by holding a non-aqueous organic electrolyte with a polymer.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a battery using a non-fluid electrolyte instead of a conventional battery using an electrolytic solution. The use of a non-fluid electrolyte is safe because there is no fear of electrolyte leakage. In particular, compared to a battery using a non-aqueous electrolyte such as a lithium secondary battery, a battery using a gel electrolyte in which this electrolyte is held by a polymer maintains the electrical characteristics of the non-aqueous electrolyte while maintaining the electrical characteristics. Since safety can be improved, its development is active.

[0003] As a method of manufacturing a battery using the gel electrolyte as described above, an electrode member forming step (A) of forming an active material layer containing an active material and a binder on a current collector;
An electrolyte paint application step (B) in which the active material layer of the electrode member obtained in the electrode member formation step (A) holds an electrolyte paint, and an electrolyte paint obtained in the electrolyte paint application step (B). At least one of the held electrode members (a)
A stacking step (C) for obtaining a battery stack in which the positive electrode and the negative electrode are stacked via an electrolyte layer by stacking using seeds; and a non-flowing step for de-fluidizing the electrolyte paint before or after the stacking step A method having a chemical conversion step (D) has been proposed.

According to the above manufacturing method, there are the following advantages. That is, since the electrode member is formed by applying and drying a paint for an electrode, it is easy to increase the ratio of the active material in the electrode member to improve the capacity. In addition, since the production of the electrode member is performed separately from the handling of the electrolyte paint that requires moisture management, there is no need for moisture management, and the production cost can be reduced.

[0005]

However, in the above-mentioned manufacturing method, there is a problem that the electrode member is warped during the application of the electrolyte paint or the non-fluidization treatment. Even if it is not such a manufacturing method, if the current collector is made thinner in order to further improve the battery capacity, the electrode member will also be warped. Such warpage of the electrode member makes subsequent handling extremely difficult,
In particular, in the case of batteries stacked in a flat plate shape, it becomes more difficult to maintain flatness, which is a bigger problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to form an active material layer containing an active material and a binder on a current collector and to provide a flat plate with little warpage. An object of the present invention is to provide an excellent method for manufacturing an electrode member and a method for manufacturing a battery suitable for a flat battery in which an electrolyte is non-fluidized.

[0007]

The present inventor has made various studies and as a result, by performing a specific treatment on the electrode member,
The inventor has found that the above object can be achieved easily, and has completed the present invention.

That is, a first gist of the present invention is to provide a method for manufacturing an electrode member comprising an active material layer containing an active material and a binder formed on a current collector. And / or a method of manufacturing an electrode member, wherein the electrode member is subjected to heat treatment in a state where pressure is applied.

The second aspect of the present invention is to provide an electrode member forming step (A) for forming an active material layer containing an active material and a binder on a current collector, and the electrode member forming step (A). (B) an electrolyte paint application step in which the active material layer of the electrode member obtained in (1) holds an electrolyte paint, and (a) an electrode member obtained in the electrolyte paint application step (B) and holding the electrolyte paint A stacking step (C) in which a positive electrode and a negative electrode are stacked with an electrolyte layer interposed therebetween to obtain a battery stack by laminating at least one of the above, and immobilizing the electrolyte paint before or after the stacking step In the method for manufacturing a battery having a non-fluidizing step (D), the electrode is formed under tension and / or pressure between the electrode member forming step (A) and the electrolyte paint applying step (B). Heat treatment process to heat-treat the members It consists in the battery production method characterized by.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, a method for manufacturing an electrode member according to the present invention will be described. In the present invention, an electrode member is manufactured by forming an active material layer containing an active material and a binder on a current collector.

As the current collector, for example, aluminum,
Examples include metal foils such as iron and copper, and polymer films having a metal thin film formed on the surface may also be used. Furthermore,
Expanded metal or punched metal may be used. Such a perforated current collector is effective in reducing the weight of the battery itself, that is, improving the weight energy density. Can also be changed freely.

By previously roughening the surface of the current collector, the effect of binding to the positive and negative electrode layers can be improved. Examples of the surface roughening method include blasting, a rolling method using a rough surface roll, abrasive cloth fixed with abrasive particles, a grindstone,
A mechanical polishing method for polishing with a wire brush provided with an emery buff, a steel wire or the like, an electrolytic polishing method, a chemical polishing method, and the like.

Further, an undercoat primer layer can be formed on the current collector. The function of the primer layer is
Improves the adhesion of the positive electrode or negative electrode active material coating layer to the current collector, reduces the internal resistance of the battery by improving the adhesion compared to the case where no primer layer is provided, reduces the current from the current collector during the charge / discharge cycle test process This is to prevent a rapid decrease in capacity due to detachment of the coating film.

The composition material of the undercoat primer layer is a resin to which conductive particles such as carbon black, graphite, and metal powder are added, and a conductive organic conjugated resin. -The type is not particularly limited as long as it has electrochemical stability.
From the viewpoint of not reducing the capacity, as the conductive particles, carbon black or graphite that can also function as an active material is used.As the resin, polyaniline, polypyrrole, polyacene, a disulfide-based compound, or a polysulfide-based compound that can function as an active material is used. It is preferable to use a compound or the like.

In the case of a composition containing a resin to which conductive particles are added as a main component, the ratio of the resin to the conductive particles is usually 1%.
To 300% by weight, preferably 5 to 100% by weight. If the proportion of the resin is too low, the coating strength of the primer layer will decrease, and if it is too high, the conductivity will decrease and battery characteristics will deteriorate. The thickness of the primer layer is usually 0.05 to 1
0 μm, preferably 0.1 to 1 μm. If the film thickness is too thin, application becomes difficult and uniformity cannot be ensured. If the film thickness is too thick, the volume capacity of the battery is impaired.

The lower limit of the thickness of the current collector is usually 1 μm, preferably 3 μm, and the upper limit is usually 50 μm, preferably 20 μm.
μm. If the current collector is too thick, the capacity of the battery is disadvantageous. If the current collector is too thin, the strength of the current collector decreases. In the present invention, since the electrode member is subjected to heat treatment as described later, the electrolyte solution is reduced even if the rigidity of the electrode is reduced by reducing the thickness of the current collector in the electrode member used for a flat battery. Since the electrode does not warp during the impregnation or the non-fluidization treatment, a thin current collector can be preferably used, and the capacity of the battery can be increased.

In the case of a lithium battery, a transition metal oxide of a transition metal such as Fe, Co, Ni, Mn, a composite oxide of lithium and a transition metal, and a transition metal sulfide can be used as the positive electrode active material. . Specifically, MnO, V ₂ O ₅ ,
Examples include transition metal oxide powders such as V ₆ O ₁₃ and TiO ₂ , composite oxide powders of lithium and transition metals such as lithium nickelate and lithium cobalt oxide, and transition metal sulfide powders such as TiS ₂ and FeS. Examples of the organic compound include a conductive polymer such as polyaniline. These inorganic compounds and organic compounds may be used as a mixture.
When the positive electrode active material is granular, the particle size is usually 1 to 3 from the viewpoint of improving battery characteristics such as rate characteristics and cycle characteristics.
It is 30 μm, preferably 1 to 10 μm.

In the case of a lithium battery, the negative electrode active material includes lithium metal, lithium alloy, graphite, core, and the like.
Use a box or the like. When the negative electrode active material is granular, the particle size is generally 1 to 50 μm, preferably 1 to 50 μm, from the viewpoint of improving battery characteristics such as initial efficiency, rate characteristics, and cycle characteristics.
It is 5 to 30 μm.

The kind of the binder is not particularly limited as long as it is stable to the active material, the electrolyte, the battery reaction, the production process of the electrode member and the like. Various resins composed of a polymer are preferably used. Specific examples thereof include alkane-based polymers such as polyethylene, polypropylene, and poly-1,1-dimethylethylene; unsaturated polymers such as polybutadiene and polyisoprene; polystyrene, polymethylstyrene, polyvinylpyridine, and poly-N-vinylpyrrolidone. Ring-based polymers such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid,
Acrylic derivative polymers such as polymethacrylic acid and polyacrylamide; fluorine resins such as polyvinyl fluoride, polyvinylidene fluoride and polytetrafluoroethylene;
C such as polyacrylonitrile and polyvinylidene cyanide
N-group-containing polymers; polyvinyl alcohol-based polymers such as polyvinyl acetate and polyvinyl alcohol; halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride;
Conductive polymers such as polyaniline; and polymers such as cellulose-based and alkoxyether-based polymers.

Further, a mixture of the above-mentioned polymers and the like, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer and the like may be used. The molecular weight of these resins is usually 10,000 to 300,000.
0, preferably 100000-1,000,000. If the molecular weight is too low, the coating strength of the active material layer will decrease, and if it is too high, the viscosity will increase and it will be difficult to form an electrode member.

In the present invention, polyvinylidene fluoride is recommended as the binder. The use of polyvinylidene fluoride is not only preferable in terms of battery performance and productivity, but also has a remarkable effect of the present invention of preventing warpage of the electrode member. In this case, the polyvinylidene fluoride may be a copolymer of vinylidene fluoride and another monomer component as long as the polymer has a segment of polyvinylidene fluoride.

The binder is used in an amount of usually 0.1 to 30 parts by weight, preferably 1 to 2 parts by weight, per 100 parts by weight of the active material.
0 parts by weight. If the amount of the binder used is too small, the strength of the electrode member is reduced, and if it is too large, the impregnation of the electrolyte paint in the production of the battery is reduced, or the ionic conductivity of the battery is reduced.

The electrode member may contain additives, such as conductive materials and reinforcing materials, which exhibit various functions, powders, fillers, and the like, if necessary. As a conductive material, usually,
Examples include carbon powder such as acetylene black, carbon black, and graphite, and fibers and foils of various metals.
In particular, carbon powder having a DBP oil absorption of 120 cc / 100 g or more, and preferably 150 cc / 100 g or more, is recommended from the viewpoint of electrolyte solution retention.

The electrode member according to the present invention is formed by binding an active material on a current collector with a binder. As such a binding method, a method in which an active material and a binder are dispersed in a solvent capable of dissolving the binder to form a coating, the coating is applied to a current collector, and then dried is suitably adopted.
As a disperser, a ball mill, a sand mill, a twin-screw kneader, or the like can be used. Examples of the coating device include slide coating and extrusion type die coating, reverse roll, gravure, knife coater, kiss coater, microgravure, knife coater, rod coater, blade coater, and the like. Considering this, the extrusion method is preferable.

If a calender treatment for consolidation is performed on the dried coating film, it is preferable from the viewpoint of improving the coating film strength and adhesiveness. In the calendering process, the temperature may be applied at the same time, and it is particularly preferable that the below-described heating process performed on the electrode member is performed after the above-described calendering step. In this case, since the distortion generated in the calendering process is removed in the heat treatment process, the arbitrariness of the calendering conditions is increased. Preferably, the calender pressure is usually 1 to 2000 kg / cm, preferably 10 to 500 kg / cm. . If it is too low, a sufficient consolidation effect cannot be obtained. If it is too high, the coating film will be crushed too much and battery characteristics will be reduced, or it will be easy to peel off from the substrate. Normal temperature is sufficient for the calendering step, but a temperature lower than the decomposition temperature of the binder may be added as necessary. In particular, it is preferable to keep the melting point of the binder or lower.

In the present invention, as described above, after forming the active material layer, it is important to heat-treat the electrode member while applying tension and / or pressure. As a method of applying tension, a method of pulling while holding both ends of the electrode member with a fixing jig can be adopted. As a pressurization method,
A method of pressing the electrode member, specifically, a method of pressing the electrode member between metal plates can be employed.

The heat treatment in the present invention is preferably performed while the electrode member is held substantially in a flat plate shape. When the above-mentioned tension and pressure are too low, the effect of the present invention cannot be sufficiently obtained, and when too high, the electrode agent may be broken. The lower limit of the tension is usually 0.001 kg / cm, preferably 0.01 kg / cm, and the upper limit is usually 100 kg / cm.
cm, preferably 50 kg / cm. The lower limit of the pressure is usually 0.001 kg / cm ² , preferably 0.01 kg / cm ² , and the upper limit is usually 10 kg / cm ² ,
Preferably, it is 0.1 kg / cm ² .

Examples of the heating means for applying tension to the electrode member include a means for blowing hot air and a means for heating with infrared rays. The heating means for applying pressure to the electrode member includes a means for sandwiching the electrode member. Means for preheating a metal plate to be used for the above. As a particularly preferable method of the heat treatment, a roll-shaped electrode member is unwound.
A method in which a traveling system having a winding device travels under tension and a heating treatment is performed by providing a heating zone along the traveling system has high productivity and can be preferably used.

The above-mentioned heating is performed so as to exceed a higher temperature of the glass transition point of the binder used for the electrode member or the room temperature (25 ° C.) (hereinafter, such a temperature is abbreviated as a reference heating temperature). Done. The preferred range of the heating temperature varies depending on the binder used for the electrode member, but is preferably selected as follows. That is, the lower limit of the heating temperature is preferably selected from a temperature 50 ° C. higher than the reference heating temperature, more preferably 100 ° C. higher than the reference heating temperature, and the lower limit of the heating temperature is preferably the decomposition temperature of the binder, more preferably the binder From the melting point of If the heating temperature is too low, it is necessary to lengthen the heating time, and if it is too high, the energy loss increases and the electrode member may be damaged.

If there is a problem in the stability of the electrode member with respect to the heat treatment, the heat treatment may be performed in an atmosphere such as nitrogen substitution, argon substitution, dry air, or vacuum. In general, when the active material layer is formed only on one side of the current collector, significant warpage occurs. However, such a problem is overcome by the present invention, and in the present invention, only one side of the current collector is used. It is possible to form an active material layer on the substrate. The electrode member obtained by the manufacturing method of the present invention is converted into an electrode (a positive electrode or a negative electrode) by causing the active material layer to hold the electrolyte paint and make it non-fluid as described later.

Next, a method for manufacturing a battery according to the present invention will be described. The manufacturing method of the present invention includes an electrode member forming step (A), an electrolyte paint applying step (B), a laminating step (C), and a non-fluidizing step (D). A feature of the present invention is that a heat treatment step is provided between the electrode member forming step (A) and the electrolyte paint applying step (B), in which the electrode member is subjected to a heat treatment under tension and / or pressure. Exists. That is, in the present invention, the above-described steps described below are performed subsequent to the above-described method for manufacturing an electrode member (electrode member forming step).

In the electrolyte paint application step (B), the electrolyte paint is held on the active material layer of the electrode member obtained in the electrode member formation step (A). The electrolyte paint is classified into a monomer-containing electrolyte paint (1) and a polymer-containing electrolyte paint (2) that can be gelled by cooling depending on the type of the non-fluidizing step (D).

The electrolyte for forming the electrolyte paint is prepared by dissolving the supporting electrolyte in a solvent. In the case of a lithium battery, a non-aqueous organic solvent is used as a solvent, and a lithium salt is used as a supporting electrolyte.

As the above-mentioned non-aqueous organic solvent, a solvent having a relatively high dielectric constant is suitable. Specific examples of such a solvent include ethylene carbonate, cyclic carbonates such as propylene carbonate, dimethyl carbonate, diethyl carbonate, acyclic carbonates such as ethyl methyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane and the like. Grimes, γ
And one or more mixtures of lactones such as -butyllactone, sulfur compounds such as sulfolane, and nitriles such as acetonitrile.

In the above, one selected from cyclic carbonates such as ethylene carbonate and propylene carbonate, and acyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.
A solvent containing one or more species is suitable from the viewpoint of battery performance. In the point that the effect of preventing warpage in the present invention is remarkable, a solvent having a relative dielectric constant of 10 or more such as ethylene carbonate, propylene carbonate, γ-butyl lactone, or acetonitrile is more preferable, and a solvent containing ethylene carbonate or propylene carbonate is more preferable. Is particularly preferred.

Examples of the lithium salt include LiPF ₆ ,
LiAsF ₆ , LiSbF ₆ , LiBF ₄ , LiClO ₄ ,
LiI, LiBr, LiCl, LiAlCl, LiHF
₂ , LiSCN, LiSO ₃ CF _{2 and the} like. Among them, LiPF ₆ and LiClO ₄ are preferable. The content of the lithium salt in the electrolyte is usually 0.5 to 2.5 m.
ol / L.

Examples of the polymerizable monomer used in the monomer-containing electrolyte paint (1) include monomers having an unsaturated double bond such as an acryloyl group, a methacryloyl group, a vinyl group and an allyl group. Specific examples thereof include acrylic acid, methyl acrylate, ethyl acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol monoacrylate, ethoxyethyl methacrylate, methoxyethyl methacrylate, ethoxyethoxyethyl methacrylate, and polyethylene glycol. Monomethacrylate, N, N diethylaminoethyl acrylate, N, N dimethylaminoethyl acrylate, glycidyl acrylate, allyl acrylate, acrylonitrile, N-vinylpyrrolidone, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate Acrylate,
Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polyalkylene glycol diacrylate,
In addition to polyalkylene glycol dimethacrylate, trifunctional monomers such as trimethylolpropane alkoxylate triacrylate and pentaerythritol alkoxylate triacrylate, and tetrafunctional or higher monomers such as pentaerythritol alkoxylate tetraacrylate and ditrimethylolpropane alkoxylate tetraacrylate No.

In the case of the monomer-containing electrolyte paint (1), the non-fluidizing step (D) comprises polymerizing the above-mentioned monomer by heat, ultraviolet rays, electron beams or the like. In this case, a polymerization initiator may be used to effectively promote the polymerization. Examples of the polymerization initiator include benzoin, benzyl, acetophenone, benzophenone, Michler's ketone, biacetyl, benzoyl peroxide, and t-
Butyl peroxy neodecanoate, α-cumyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, 1-cyclohexyl-1-methylethyl peroxy neodecanoate, t-amyl peroxy neodecanoate Peroxy neodecanoates such as noate, t-
Butyl peroxy neoheptanoate, α-cumyl peroxy neo heptanoate, t-hexyl peroxy neo heptanoate, 1-cyclohexyl-1-methylethyl peroxy neo heptanoate, t-amyl peroxy heptanoate Peroxyneoheptanoates such as ate.

Examples of the polymerizable monomer include, in addition to the above, polymers such as polyesters, polyamides, polycarbonates, and polyimides formed by polycondensation, polyurethanes, and the like.
It is also possible to use a monomer which produces a polymer produced by polyaddition such as polyurea.

As the polymer used in the polymer-containing electrolyte coating material (2), a polymer that dissolves in an electrolyte at a high temperature and forms a gel electrolyte at a normal temperature is preferably used. Specific examples of such polymers include ring polymers such as polyvinylpyridine and poly-N-vinylpyrrolidone; polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, Acrylic derivative polymers such as polyacrylic acid and polymethacrylic acid polyacrylamide; fluorine resins such as polyvinyl fluoride and polyvinylidene fluoride;
C such as polyacrylonitrile and polyvinylidene cyanide
N-group-containing polymers; polyvinyl alcohol-based polymers such as polyvinyl acetate and polyvinyl alcohol; and halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride. Further, it may be a mixture of the above-mentioned polymers and the like, a modified product, a derivative, a random copolymer, an alternating copolymer, a graft copolymer, a block copolymer, and the like.

As described later, since the electrolyte and the electrolyte used in the lithium battery have polarity, it is preferable that the above-mentioned polymer also has a certain degree of polarity. The molecular weight of these polymers is usually 10,000 to 50,000.
00 range. If the molecular weight is too low, it will be difficult to form a gel, and if the molecular weight is too high, the viscosity will be high and handling will be difficult.

The concentration of the polymer in the electrolyte is preferably 0.1 to 30% by weight. If the concentration is less than 0.1% by weight, it becomes difficult to form a gel, the retention of the electrolyte is reduced, and problems of flow and liquid leakage occur. If the concentration is more than 30% by weight, the viscosity becomes too high, causing difficulty in the process, and the proportion of the electrolytic solution is reduced, the ionic conductivity is reduced, and the battery characteristics such as rate characteristics are deteriorated.

In the laminating step (C), the positive electrode is laminated by using at least one of the electrode members (a) obtained in the electrolyte paint applying step (B) and holding the electrolyte paint. And a battery laminate in which the negative electrode is laminated via an electrolyte layer.

In a preferred embodiment of the present invention, the respective electrode members for the positive electrode and the negative electrode obtained in the electrode member forming step (B) are used, and one of the electrodes (usually the negative electrode) is made of a material such as lithium foil. It can be composed of metal itself.

In a preferred embodiment of the present invention, the electrolyte layer disposed between the positive electrode and the negative electrode is formed by using a sheet prepared by dipping in an electrolyte paint.
However, the method for forming the electrolyte layer is not limited to such a method. When the electrolyte paint is held on the active material layer of at least one of the electrode members in the electrolyte paint coating step (B), the electrolyte is formed between the positive electrode and the negative electrode. A method of holding an amount of the electrolyte paint sufficient to form an electrolyte layer may be used.

As the sheet (film) for supporting the electrolyte paint, various porous membranes and non-woven fabrics used as battery separators can be used. Specifically, papers such as paper and Japanese paper, Examples include cloths made from various natural and synthetic fibers, and commercially available filters used for separation and purification. In particular, the method of using a polymer porous film and simultaneously performing the non-fluidization treatment of the positive electrode, the electrolyte layer, and the negative electrode has a structure in which the non-fluidized electrolyte is continuous,
Excellent in strength and ionic conduction. The lower limit of the thickness of the sheet is usually 5 μm, preferably 10 μm, and the upper limit is usually 200 μm, preferably 150 μm, more preferably 80 μm.

In the non-fluidizing step (D), the electrolyte paint is non-fluidized. The non-fluidizing step (D) is preferably performed after the laminating step (C) from the viewpoint of reducing the internal resistance and improving the cycle characteristics and the rate characteristics.
The method of the non-fluidizing step (D) is appropriately selected depending on the type of the electrolyte paint as described above.

In the packaging process after the lamination process, the battery laminate obtained as described above is sealed in a case. In this case, a plurality of battery stacks are stacked as needed. When sealing the battery stack in the case after stacking,
It is necessary to prevent the electrode member from warping until it is sealed in the case, and the effect of the present invention for preventing warpage is remarkably exhibited.
Examples of the case include a lightweight and thin laminated film. As the laminate film, a film composed of a laminate material of a metal foil and a polymer film can be suitably used. Vacuum sealing is preferably adopted, and the battery stack is sealed in a case while maintaining the flat plate shape. In addition, for convenience such as mounting of the battery in a device, it is possible to enclose the battery in a case and then store a plurality of cases in a rigid outer case if necessary.

[0049]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention can be appropriately modified and practiced without changing the gist thereof. I can do it. Parts in the composition indicate parts by weight.

Examples 1 to 17 and Comparative Examples 1 to 6 First, a positive electrode paint and a negative electrode paint having the following compositions were prepared. That is, all the following raw materials were kneaded for 2 hours by a kneader to obtain a paste. The polyvinylidene fluoride used was
Glass transition temperature is -40C, melting point is 160-170C,
The decomposition temperature is 350 ° C.

[0051]

<Table 1> <Composition of positive electrode paint> Lithium cobaltate 90 parts Acetylene black 5 parts Polyvinylidene 5 parts N-methylpyrrolidone 80 parts

[0052]

[Table 2] <Composition of negative electrode paint> 90 parts of graphite (particle size 15 μm) 10 parts of polyvinylidene fluoride 100 parts of N-methylpyrrolidone

Next, an electrolyte paint having the following composition was prepared. That is, all the following raw materials were dissolved by mixing and stirring.

[0054]

[Table 3] <Composition of electrolyte paint> Tetraethylene glycol diacrylate 14 parts Polyethylene oxide triacrylate 7 parts Lithium perchlorate 21 parts Polymerization initiator 1 part Additive (spirodilactone) 14 parts Electrolyte solution (propylene carbonate) 120 parts Electrolyte (ethylene carbonate) 120 parts

Next, the positive electrode paint was applied on a 20 μm-thick aluminum current collector base material, and the negative electrode paint was applied on a 20 μm-thick copper current collector base material by extrusion die coating. A porous electrode member was prepared in which the substance was bound on the current collector by a binder. After this, use a roll press (calendar)
The electrode member was consolidated at a linear pressure of 200 kgf / cm.

Next, while the roll-shaped electrode member is run under tension in a running system having an unwinding and winding device, the electrode member is provided on the way of the running system and the electrode member is held in a substantially flat shape. Heat treatment was performed in the obtained heating zone. In addition, some samples were cut out separately and subjected to a heat treatment in a state where press pressure was applied by a flat plate press. Table 5 shows the tension, pressure, heating temperature, and heating time employed in each of the examples and the comparative examples.

An electrolyte paint is applied to the heat-treated positive and negative electrode members, and a polymer porous film prepared by immersing the electrolyte paint in the electrolyte paint is interposed therebetween.
A flat unit having a positive electrode and a negative electrode formed on a current collector containing an active material and a binder by heating for 0 minutes to make the electrolyte non-fluid, and having a non-fluidized electrolyte component A battery element was formed. A tab for taking out current was connected to the terminal battery element, and a vacuum-sealed and stored in a bag-like case formed by facing a laminate film made of an aluminum film and a polymer film to obtain a flat battery.

<Evaluation of Characteristics> As evaluations in the above Examples and Comparative Examples, the warpage (flatness) of the electrode members during the impregnation with the electrolyte was visually evaluated. The results are shown in Tables 5 and 6. The criteria for visual evaluation of warpage are as follows.

[0059]

○: Substantially no warp, no difficulty in laminating positive electrode, negative electrode, porous film, and subsequent non-fluidizing treatment. Δ: Warpage is slight, and care must be taken in positioning and lamination in laminating a positive electrode, a negative electrode, and a porous film. It is necessary to hold the laminate lightly in the subsequent non-fluidization treatment. X: The warpage is large and the electrode agent curls. Positioning and lamination of the positive electrode, the negative electrode and the porous film are extremely difficult. It is necessary to hold the laminate firmly in the subsequent non-fluidization treatment.

[0060]

[Table 5]

[0061]

[Table 6]

[0062]

According to the present invention as described above, a method for producing an electrode member which is formed by forming an active material layer containing an active material and a binder on a current collector, has less warpage, and is excellent in flatness, Further, a method for producing a battery suitable for a flat battery in which the electrolyte is not fluidized is provided, and the industrial value of the present invention is remarkable.

Continued on front page F-term (reference)

Claims (11)

[Claims] 1. A method for manufacturing an electrode member comprising forming an active material layer containing an active material and a binder on a current collector, wherein after forming the active material layer, a tension and / or pressure is applied. A method for manufacturing an electrode member, comprising heating the electrode member. 2. The method according to claim 1, wherein a coating containing an active material and a binder is applied on a current collector and then dried to form an active material layer. 3. The method according to claim 1, wherein a calendering process is performed after the formation of the active material, followed by a heating process. 4. The method according to claim 1, wherein the heat treatment is performed while the electrode member is held substantially in a flat plate shape. 5. The method according to claim 1, wherein after the electrode member is wound in a roll shape, the electrode member is subjected to a heat treatment while running under tension in a running system having an unwinding and winding device. Production method. 6. The method according to claim 1, wherein an active material layer is formed only on one side of the current collector. 7. An electrode member forming step (A) for forming an active material layer containing an active material and a binder on a current collector, and the active material of the electrode member obtained in the electrode member forming step (A). Electrolyte paint application process (B) to hold electrolyte paint in layer
And a positive electrode and a negative electrode are laminated via an electrolyte layer by laminating using at least one of the electrode members (a) obtained in the electrolyte paint coating step (B) and holding the electrolyte paint. (C) to obtain a battery laminate comprising
And a method for producing a battery having a non-fluidizing step (D) for defluidizing the electrolyte paint before or after the laminating step, wherein the electrode member forming step (A) and the electrolyte paint applying step (B) A heat treatment step of subjecting the electrode member to heat treatment in a state where tension and / or pressure is applied therebetween. 8. The active material of the positive electrode and the negative electrode used in the electrode member forming step (A) is an active material capable of inserting and extracting lithium ions, and the electrolyte used in the electrolyte paint applying step (B) is lithium ion. The method according to claim 7, further comprising: 9. The binder used in the electrode member forming step (A) contains polyvinylidene fluoride, and the electrolyte raw material used in the electrolyte paint coating step (B) contains a solvent having a relative dielectric constant of 10 or more. 9. The production method according to 7 or 8. 10. The manufacturing method according to claim 7, further comprising a packaging step of enclosing the battery stack in a case after the stacking step. 11. The method according to claim 7, wherein in the packaging step, the battery laminate is sealed in a case while being maintained in a flat shape.