JP2000133248A - Manufacture of thin film type battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture thin film type batteries that are effectively free of short circuits and dendrites in a productive manner. SOLUTION: A positive electrode base forming step and a negative electrode base forming step form a positive active material layer and a negative active material layer on different long conductive carriers to produce a positive electrode base and a negative electrode base. A laminating step laminates the positive and negative electrode bases with their active material layers in face-to-face relation to form a battery laminate base. A cutting step cuts the battery laminate base generally across the length into battery laminates having a positive electrode 21 and a negative electrode 22. A part-cutting step cuts at least part of the battery laminate base or either electrode of each battery laminate before or after the cutting step to make one electrode smaller than the other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a thin-film battery.

[0002]

2. Description of the Related Art Thin-film batteries, such as thin-film lithium secondary batteries, in which a positive electrode, a negative electrode, and an electrolyte layer in which an electrolyte is held in a polymer are each formed in a thin film form, usually use a negative electrode active material as an electrode substrate. The anode is formed by laminating a negative electrode formed thereon and a positive electrode formed on a separate electrode substrate with a positive electrode active material, with an electrolyte layer interposed and the respective active material layers facing each other. Generally, a separator is interposed between the positive electrode and the negative electrode for the purpose of preventing a short circuit between the positive electrode and the negative electrode, and the area of the negative electrode is set smaller than the area of the positive electrode for the purpose of preventing generation of dendrite at an edge portion. , And smaller than the area of the separator. In order to obtain batteries having different sizes of the positive electrode and the negative electrode, there are great restrictions on the manufacturing process. That is, a positive electrode, a negative electrode, and a separator having different sizes are prepared in advance, and then these are laminated.

[0003]

However, in the above-described conventional manufacturing method, electrodes having different sizes are separately formed for each of the positive electrode and the negative electrode, and an electrolyte and a separator are formed on these electrodes to perform accurate alignment. There is a need. That is, not only is it necessary to handle the electrodes in a single sheet, but also it is necessary to perform accurate positioning, and thus there is a problem that productivity is poor and a defective rate is high. On the other hand, if the laminated raw material is cut after laminating the long raw materials of the positive electrode and the negative electrode, the above problem itself can be solved.
In this case, since the size of the positive electrode and the size of the negative electrode are the same, the above-described problem of the occurrence of short-circuit and dendrite occurs.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, in the method of cutting after the lamination of the webs, the lamination of the long webs was performed. The inventors have found that if only a part of the electrode is cut later to make the electrode smaller than the other electrode, a thin-film battery in which occurrence of short circuit and dendrite is prevented can be manufactured with high productivity, and the present invention has been completed. That is, the gist of the present invention is to provide a method of manufacturing a thin film battery comprising a positive electrode, a negative electrode, and a gel electrolyte layer formed between the positive electrode, the negative electrode, and (1) forming a positive electrode on a different long conductive support. A positive electrode raw material forming step of forming an active material layer and a negative electrode active material layer to obtain a positive electrode raw material and a negative electrode raw material, and a negative electrode raw material forming step, and (2) the positive electrode raw material and the negative electrode raw material, A laminating step of laminating the active material layers in a facing direction to obtain a raw battery laminate, and (3) cutting the raw battery laminate in a direction substantially perpendicular to the longitudinal direction to form a positive electrode and a negative electrode. (4) a cutting step of obtaining a battery laminate having
Before or after the cutting step, a partial cutting step of cutting at least a part of one electrode portion of the original battery stack or the battery stack, and reducing the size of the one electrode to be smaller than the other electrode. A method for manufacturing a thin film battery characterized by having

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Step of Forming Positive Electrode and Step of Forming Negative Electrode In the present invention, first, a positive electrode active material layer and a negative electrode active material layer are respectively formed on separate long conductive supports. . The active material layer for the positive and negative electrodes may be formed by any method, but it is preferable that the formed active material layer has a void that can be impregnated with an electrolyte component later. The same electrolyte as the electrolyte layer to be formed is formed in the gap, and this can be integrally formed with the electrolyte layer. As a preferable method, there is a method in which components constituting the active material are dispersed and coated with an appropriate solvent, and the resultant is coated on a long conductive support and dried. Alternatively, a method of pressing or spraying the active material layer component on a support may be used. By adding a calendering step to the formed coating film, it is possible to consolidate the coating film and increase the filling amount of the active material. The degree of consolidation is determined by the balance between the amount of the active material filled and the ionic conductivity of the electrolyte portion filling the void.
Note that an intermediate layer may be provided between the support and the active material layer to improve the adhesion between the support and the active material layer. For the same reason, the surface of the support may be subjected to a roughening treatment.

Various coating methods such as slide coating, extrusion die coating, reverse roll, gravure, knife coater, kiss coater, microgravure, knife coater, rod coater, blade coater and the like can be applied. Of course, it is also possible to combine these application methods. Further, depending on the wet state and viscosity of the paint, it is also possible to transfer and apply the wet paint already applied to another support. The thickness of the formed active material layer is usually 1 μm.
Above, preferably 5 μm or more, and usually 500 μm or less, preferably 300 μm or less. If the thickness is too large, the rate characteristics tend to decrease, and if it is too thin, the capacity tends to decrease. The long conductive support finally becomes an electrode base material of the battery. Therefore, usually metals or alloys such as aluminum and copper are used.

[0007] It is preferable that the obtained raw materials of the positive electrode and the negative electrode are each held with an electrolyte component by means of coating or the like before laminating them, for ease of production.
The electrolyte component may have the same composition as the electrolyte layer, or may have the same composition as the electrolyte layer by a predetermined treatment. For example, as a preferred embodiment, a liquid composed of a supporting electrolyte, a non-aqueous solvent, and a monomer is held as a component of the electrolyte by means such as coating, and then the monomer is polymerized by adding a polymerization treatment such as ultraviolet irradiation or heating. Then, a gel polymer electrolyte in which the formed polymer holds an electrolyte solution comprising an electrolyte salt and a non-aqueous solvent can be obtained.

In the above-mentioned electrolyte component holding step, since the electrolyte component is a raw material constituting the electrolyte layer, it is preferable that the electrolyte component be sufficiently present on the surface of the active material layer after coating. However, this does not apply to the case where a separator raw is present between the positive electrode raw material and the negative electrode raw material in the laminating step, and the separator raw material is impregnated with an electrolyte component, as described later. When the active material layer has a void, the electrolyte component applied in the above-mentioned electrolyte solution applying step is not only a raw material for forming the electrolyte layer, but also a raw material for the electrolyte charged in the void.

(2) Laminating Step The raw materials of the positive electrode and the negative electrode are then laminated in a state where the active material layers face each other in a state of being aligned in the longitudinal direction to obtain a raw battery laminate. At this time, it is preferable that the laminate is laminated with a long separator raw material interposed between the positive electrode raw material and the negative electrode raw material. As a result, the battery can easily prevent a short circuit. At this time, it is preferable to impregnate the raw material of the separator with an electrolyte component since the electrolyte layer can be formed. After lamination, it is also possible to cause the electrolyte component to exist between the positive electrode raw material and the negative electrode raw material, but as described above, preferably, the electrolyte component is applied to each raw material before lamination, And / or the separator is impregnated with the electrolyte component. In any case, when the above-mentioned electrolyte component contains a non-aqueous solvent, an electrolyte salt and a monomer, a polymerization step of polymerizing the monomer after lamination and before cutting and partially cutting the laminate raw material It is preferred to add As a result, it is possible to easily form a gel-like polymer electrolyte in which an electrolyte containing a non-aqueous solvent and an electrolyte salt is held in a polymer at a time. Also, in this case,
Since the clay of the electrolyte component is relatively low, it is easy to apply or impregnate. Examples of the polymerization method include a method of irradiating ultraviolet rays and a method of applying heat, and a method of thermally polymerizing by applying heat is preferable because the polymerization reaction proceeds uniformly.

The above-mentioned polymerization step can be provided, if necessary, after a cutting step or a partial cutting step described later.
The polymerization conditions at the time of thermal polymerization need to consider the thermal stability and the like of each material forming the electrolyte layer.
The temperature is set to 00 ° C, preferably 70 to 90 ° C. The shorter the polymerization time is, the lower the polymerization time is, usually, 5 minutes or less, preferably 3 minutes or less, from the viewpoint of productivity, decomposition of materials, and the like. In addition, the positive electrode layer, electrolyte layer, and negative electrode layer are integrally molded and then gelled,
Since no interface exists in the gel electrolyte between the negative electrode layer and the electrolyte layer, battery characteristics can be improved. The sheet integrally formed of the positive electrode / electrolyte layer / negative electrode prepared as described above is cut into a desired size, and if necessary, laminated to form a thin-film battery.

(3) Cutting Process The battery laminate raw material obtained by laminating the positive electrode raw material and the negative electrode raw material is then subjected to a longitudinal cutting process before or after a partial cutting process described later. The battery is completely cut in a substantially vertical direction to form a battery stack. That is, in the cutting step, the positive electrode raw material and the negative electrode raw material, and in some cases, the separator raw material are simultaneously cut at a time, respectively, to obtain a battery stack having a generally rectangular shape. As the cutting method, the same method as the method used in the partial cutting step described later can be used, but since it is not necessary to strictly control the cutting depth as in the partial cutting step, a punching die or the like is used. You may cut | disconnect by punching with a cutting blade.

(4) Partial cutting step The battery laminate obtained by laminating the positive electrode material and the negative electrode material, or the battery laminate obtained by cutting the laminate material, At least a part of one of the electrode portions is cut off so that the size of the one electrode is smaller than that of the other electrode. When the raw battery laminate is partially cut, there is a cutting step after that. Therefore, in the partial cutting process, only a cut is made in one electrode of the long raw material. Further, when the battery stack is partially cut, a cut is formed in one electrode of the stack.

It is preferable to partially cut the positive electrode side as an electrode to be partially cut, from the viewpoint of preventing short circuit and generation of dendrite. As the cutting direction of the partial cutting, when partially cutting the original battery stack, it is usually a direction substantially perpendicular to the long direction, but when cutting the battery stack,
There is no major problem in any direction of the rectangular laminated body, and it can be partially cut in the same direction as that cut in the cutting step or in a direction substantially perpendicular thereto. However, also in the latter case, in the width direction of the raw material, by cutting the width of the raw material and the width of the active material layer, cutting in particular is not necessary. Of course, partial cutting is 1
It may be performed at a plurality of locations for one battery stack. The cutting depth at the time of partial cutting is not less than the depth at which the electrode to be partially cut is cut, but if there is a separator between the electrodes, the separator is set to such a depth that the separator is not cut. Is preferred.

As a method for partial cutting, a disk-shaped blade made by molding high-hardness fine particles such as diamond with a resin or the like, a metal saw using high-speed steel or carbide or a diamond tip, a rotary blade such as a router, A method using a knife such as a cutter knife or a razor, a single-blade round blade, a knife blade such as an ultrasonic cutter, a die-cut type blade represented by a Thomson blade, or a guillotine blade is exemplified. The cutting speed for a rotary blade or knife blade is usually 10 mm / min to 100 / m
in, more preferably 100 mm / min to 50 m /
min. If the speed is too slow, the productivity is extremely poor. If the speed is too fast, the edge accuracy is poor and a short circuit is likely to occur.

For example, when a metal saw is used, the number of rotations of the rotary blade is 100 rpm to 10,000 rpm, more preferably 300 rpm to 5000 rpm. Even if the number of rotations is too slow or too fast, the edge accuracy at the time of cutting is poor and short-circuiting is likely to occur. In the partial cutting step, only one of the electrodes is usually cut, so it is necessary to make the cutting depth strict, and usually some control is required. That is, preferably, the position in the thickness direction of the cut portion from the reference position of the battery stack or the original battery stack is measured, and the cutting depth is controlled based on the result. As a control method, for example, an electrode substrate surface near a cutting point is set as a reference position, and an LD
There is a method of irradiating light, receiving the reflected light by a light receiving element, and converting the intensity of the light into an electric signal. At this time, a knife or the like for cutting is attached to, for example, the piezo element, and the piezo element is distorted by an electric signal proportional to the light intensity input to the light receiving element to control the knife position.

(5) Others The unit cell obtained through the cutting step and the partial cutting step is as follows:
Finally, the terminals electrically connected to the electrode base material are housed in a container so as to be exposed to the outside. At this time, a plurality of unit cells may be stored in the container. Usually, unit cells are stored in a container in a sheet form. In the unit cell obtained through the cutting step and the partial cutting step, an electrode base material or an active material layer partially cut at an end may still remain. These may be left as long as they do not impair the function of the battery, but are usually removed before being housed in a container from the viewpoint of preventing the occurrence of short-circuit and dendrite. Examples of the removing method include a method of picking and peeling an end portion, a method of bonding and peeling off with a tape, and a method of scraping off.

A preferred embodiment of the present invention will be described below with reference to FIGS. 1 and 2 are schematic views for explaining the manufacturing method of the present invention. The positive electrode raw material 1 obtained by applying the positive electrode active material layer coating material to a long metal foil and then drying is unwound from a roll 2 and then contains an electrolyte salt, a non-aqueous solvent and a monomer by a coater 3. The electrolyte component is applied. Similarly, the negative electrode raw material 4 obtained by applying the negative electrode active material layer coating material to a long metal foil and then drying is unwound from a roll 5, and then the same electrolyte component is applied by a coater 6. Applied. The long separator web 7 is also unwound from the roll 8 and the same electrolyte component is applied by the coater 9.

Each raw material is pressed and laminated by a pair of rollers 10 having a slight space. After the lamination, the laminated body is heated by the heater 11, the monomers in the electrolyte component are polymerized, and the electrolyte becomes a gel-like polymer electrolyte. Next, the laminate is
A rectangular sheet 1 cut in a direction substantially perpendicular to the long direction
3 is obtained. Next, a part of the positive electrode 21 of the rectangular sheet 13 is cut at a predetermined distance from the cut end surface (indicated by a dotted line 14 in FIG. 2). The unit cell 24 having the negative electrode 22, the electrolyte layer 23 having the separator, and the positive electrode 21 'having a smaller area than the negative electrode 22 and the electrolyte layer 23 is obtained by the partial cutting described above. At this time, while performing feedback control while monitoring the cutting depth,
Perform a partial cut. The remaining positive electrode portion 25 generated by the partial cutting is then removed. In the above preferred embodiment, the width of the raw material of the positive electrode and the negative electrode is smaller than the width of the raw material of the separator. As described above, by reducing the width of the raw material of the positive electrode and the negative electrode itself to be smaller than the raw material of the separator, or by reducing the width of the active material layer to be smaller than the width of the raw material of the separator, particularly in the width direction of the electrode. There is no need to cut a part.

There are no particular restrictions on the materials that can be used for the positive electrode, the negative electrode, and the electrolyte layer. Hereinafter, the case of a lithium secondary battery using a preferably used polymer electrolyte will be described. The positive electrode active material layer usually contains a positive electrode active material capable of inserting and extracting lithium ions and a binder. In the case of a binder with respect to 100 parts by weight of the active material, preferably 0.1 to 30 parts by weight, more preferably 1 to 1 part by weight.
5 parts by weight. If the amount of the binder is too small, a strong active material layer cannot be formed, and the object of the present invention in which the active material layer holds the active material cannot be achieved. If the amount of the binder is too large, not only has an adverse effect on the energy density and cycle characteristics, but also when the active material layer contains an electrolyte component, it is difficult to impregnate the electrolyte component because the amount of voids in the active material layer is reduced. .

Examples of the positive electrode active material include various inorganic compounds such as a transition metal oxide, a composite oxide of lithium and a transition metal, and a transition metal sulfide. Here, Fe, Co, Ni, Mn, or the like is used as the transition metal. In particular,
Transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ and TiO ₂ , lithium nickelate, lithium cobaltate,
Examples thereof include a composite oxide powder of lithium and a transition metal such as lithium manganate, and a transition metal sulfide powder such as TiS ₂ , FeS, and MoS ₂ . These compounds may be partially substituted with elements in order to improve their properties. Further, organic compounds such as polyaniline, polypyrrole, polyacene, disulfide compounds, polysulfide compounds, and N-fluoropyridinium salts can also be used. These inorganic compounds and organic compounds may be used as a mixture.

The active material of the positive electrode generally has a particle size of 1 to 3.
0 μm, especially 1 to 10 μm, rate characteristics,
Battery characteristics such as cycle characteristics are further improved. As the binder used for the positive electrode active material layer, polyethylene,
Alkane-based polymers such as polypropylene and poly-1,1-dimethylethylene; unsaturated polymers such as polybutadiene and polyisoprene; polymers having a ring such as polystyrene, polymethylstyrene, polyvinylpyridine and poly-N-vinylpyrrolidone; Acrylic derivative polymers such as methyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl fluoride,
Fluorinated resins such as polyvinylidene fluoride and polytetrafluoroethylene; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide; polyvinyl alcohol polymers such as polyvinyl acetate and polyvinyl alcohol; polyvinyl chloride and polyvinylidene chloride Various resins such as a halogen-containing polymer and a conductive polymer such as polyaniline can be used. In addition, a mixture of the above-described polymers, a modified substance, a derivative, a random copolymer,
Even an alternating copolymer, a graft copolymer, a block copolymer, or the like can be used. Also, inorganic compounds such as silicate and glass can be used. However, in order to achieve the object of the present invention, it is not preferable to use a resin that easily dissolves in the electrolytic solution. The weight average molecular weight of the resin is preferably 10,000 to 1,000,000, and more preferably 20,000 to 300,000. If it is too low, the strength of the coating film decreases, which is not preferable. If it is too high, the viscosity becomes high and it becomes difficult to form an active material layer.

The positive electrode active material layer may contain additives, such as a conductive material and a reinforcing material, exhibiting various functions such as a reinforcing material, a powder, and a filler, if necessary. The conductive material is not particularly limited as long as it can impart conductivity by being mixed in an appropriate amount with the above active material, but is usually carbon powder such as acetylene black, carbon black, graphite, and various metal fibers and foils. Is mentioned. Various inorganic materials as reinforcement,
Organic spherical or fibrous fillers can be used. The thickness of the positive electrode active material layer is usually 1 μm or more, preferably 10 μm or more, usually 500 μm or less, preferably 200 μm or less.
m or less.

As the electrode base material of the positive electrode, generally, a foil such as a metal such as an aluminum foil or a copper foil, or an alloy is used. The thickness is usually 1 to 50 μm, preferably 1 to 30 μm. If the thickness is too small, the mechanical strength becomes weak, which causes a problem in production. If it is too thick, the capacity of the battery as a whole decreases. The negative electrode active material layer basically conforms to the configuration of the positive electrode active material layer except that the active material is an active material for a negative electrode. Examples of the negative electrode active material used for the negative electrode include carbon-based active materials such as graphite and coke. These carbon-based active materials can be used in the form of a mixture with a metal, a salt thereof, or an oxide, or a coating. In addition, oxides such as silicon, tin, zinc, manganese, iron, and nickel, or sulfates, and metal lithium and Li-A
1, a lithium alloy such as Li-Bi-Cd and Li-Sn-Cd, a lithium transition metal nitride, silicon and the like can also be used. The particle size of these negative electrode active materials is usually 1 to 50 μm.
m, especially 15 to 30 μm, is preferable because battery characteristics such as initial efficiency, rate characteristics, and cycle characteristics are improved.

Next, the polymer electrolyte will be described. In the present invention, preferably, the voids in the active material layers of the positive electrode and the negative electrode are filled with a gel-like polymer electrolyte, and the ion conduction of lithium ions moves to the gel-like electrolyte layer through the gel-like electrolyte. As a result, the nonaqueous electrolytic solution of all of the positive electrode, the negative electrode and the electrolyte layer becomes gel-like, and a safe lithium secondary battery without liquid leakage can be obtained.

In the present invention, preferably, a fluid electrolyte which can be a gel polymer electrolyte is applied as an electrolyte component, and after the application, the polymer electrolyte is formed by a predetermined treatment. As such an electrolyte component, those containing an electrolytic solution composed of an electrolytic salt such as a lithium salt and a solvent and a monomer are preferable. In this case, the electrolytic solution is retained in the polymer by polymerizing the monomer later. Examples of such a polymer include those formed by polycondensation of polyester, polyamide, polycarbonate, and polyimide; those formed by polyaddition such as polyurethane and polyurea; acrylic derivative-based polymers such as polymethyl methacrylate; Although there are those produced by addition polymerization of polyvinyl acetate and the like such as polyvinyl acetate and polyvinyl chloride, etc., in the present invention, it is preferable that the active material layer is impregnated and polymerized. It is desirable to use a polymer produced by addition polymerization in which no by-product is generated during the polymerization.

The electrolyte salt contained in the electrolytic solution is stable as an electrolyte with respect to the positive electrode active material and the negative electrode active material, and migrates for lithium ions to undergo an electrochemical reaction with the positive electrode active material or the negative electrode active material. Any non-aqueous substance that can be used can be used. LiPF ₆ in particular, LiAsF _6, LiSbF _6, Li
BF ₄ , LiClO ₄ , LiI, LiBr, LiCl,
LiAlCl, LiHF ₂ , LiSCN, LiSO ₃ C
F _2, and the like. Among these, LiP
F ₆ and LiClO ₄ are preferred. The content of these electrolyte salts in the electrolyte is generally 0.5 to 2.5 mol.
/ L.

The electrolytic solution in which these electrolytes are dissolved is not particularly limited, but a non-aqueous solvent having a relatively high dielectric constant is preferably used. Specifically, cyclic carbonates such as ethylene carbonate and propylene carbonate, acyclic carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, glymes such as tetrahydrofuran, 2-methyltetrahydrofuran and dimethoxyethane, γ-butyl lactone and the like Lactones,
One or a mixture of two or more of sulfur compounds such as sulfolane and nitriles such as acetonitrile can be mentioned. Of these, especially ethylene carbonate,
One or more mixed solutions selected from cyclic carbonates such as propylene carbonate, and non-cyclic carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferred. Further, those obtained by substituting a part of hydrogen atoms of these molecules with halogen or the like can also be used.

As the polymer constituting the gel electrolyte, a polymer capable of holding an appropriate amount of the electrolytic solution to form a gel is used. Usually, since the above-mentioned electrolytic solution has polarity, it is preferable that the polymer also has a certain degree of polarity. As aforementioned,
When a polymer is formed by addition polymerization, an impregnating liquid is prepared by mixing a monomer having at least one reactive unsaturated group in the molecule with the electrolyte usually in an amount of about 1 to 20% by weight. At this time, if the monomer has a highly polar group such as ethylene oxide, propylene oxide, phenylene oxide, phenylene sulfide, cyano, and carbonate in the molecule, it is possible to impart appropriate polarity to the produced polymer, and it is preferable. A good gel can be formed. The gel may be formed of only a linear polymer, but the number of reactive groups in the monomer is controlled to have a branched structure,
Forming a branched structure is preferable because mechanical properties and the like are improved.

Examples of the monomer having a reactive unsaturated group include acrylic acid, methyl acrylate, ethyl acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol monoacrylate, ethoxyethyl methacrylate, and methoxyethyl. Methacrylate, ethoxyethoxyethyl methacrylate, polyethylene glycol monomethacrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, glycidyl acrylate, allyl acrylate, 2-methoxyethoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate, acrylonitrile , N-vinylpyrrolidone, diethylene glycol diacrylate, triethyl Glycol diacrylate,
Tetraethylene glycol diacrylate, polyethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and the like can be used. Alternatively, they may be used in combination.

As a method for polymerizing these monomers, there are methods using heat, ultraviolet rays, electron beams, etc., but a method using heat which is easy to integrally form the positive electrode layer / electrolyte layer / negative electrode layer is effective. In this case, in order for the reaction to proceed effectively, a polymerization initiator that reacts with heat may be added to the electrolyte to be impregnated. Usable thermal polymerization initiators include azo compounds such as azobisisobutyronitrile, dimethyl 2,2'-azobisinbutyrate, benzoyl peroxide, cumene hydroperoxide, t-butylperoxy-2-ethylhexano. Peroxides such as ate can be used, and those which are preferable in terms of reactivity, polarity, safety, etc. may be used alone or in combination. The electrolyte of the electrolyte layer is preferably impregnated in a separator made of a porous membrane or a nonwoven fabric. The thickness of the electrolyte layer is usually 1μ
m, preferably 5 μm or more, and usually 500 μm or less, preferably 200 μm or less. If it is too thick, the capacity tends to decrease, and if it is too thin, the insulation tends to decrease.

[0031]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist. The raw materials used in both the examples and comparative examples are as follows.
Vacuum dried at 0 ° C for 24 hours. Resin and electrolyte are 110 ° C.
For 4 hours, and the monomer was used after being dehydrated with a molecular sieve. Example 1 First, a paint for a positive electrode active material layer and a paint for a negative electrode active material layer were prepared according to the following compositions. The following were used as raw materials for the positive electrode paint and the negative electrode paint.

[0032]

Table 1 Positive electrode active material LiCoO ₂ powder (manufactured by Nippon Chemical Co., Ltd.) Conductive material Acetylene black (manufactured by Denki Kagaku Kogyo) Negative electrode active material SFG15: graphite (manufactured by TIMCAL) Binder Polyvinylidene fluoride (manufactured by Kureha Chemical) Solvent N-methylpyrrolidone (Mitsubishi Chemical)

[0033]

[Table 2] (Coating composition of positive electrode active material layer) LiCoO ₂ powder 90.0 parts Acetylene black 5.0 parts Polyvinylidene fluoride 5.0 parts N-methylpyrrolidone 100.0 parts

[0034]

[Table 3] (Negative electrode active material layer coating composition) SFG15 90.0 parts Polyvinylidene fluoride 10.0 parts N-methylpyrrolidone 100.0 parts

Each of the above materials was kneaded and dispersed in a ball mill for 8 hours to form a coating. Next, the coating for the positive electrode active material layer was coated on a long aluminum foil having a thickness of 20 μm to a thickness of 100 μm by an extrusion day coating method.
And dried to obtain a positive electrode raw material. Further, the negative electrode active material layer coating material was applied on a long copper foil having a thickness of 20 μm using a doctor blade so that the film thickness became 150 μm, and dried to obtain a negative electrode raw material. Thereafter, each active material layer was dried at 240 ° C. The sheet provided with the above-mentioned positive electrode / negative electrode active material layer on the current collector was subjected to calendering (pressure) treatment to give a final film thickness of 75 μm for the positive electrode and 60 μm for the negative electrode.

Each of the positive and negative electrode raw materials thus obtained was impregnated with the following electrolyte components, and a 20-μm-thick porous polyethylene separator impregnated with the same electrolyte components was prepared. The positive electrode raw material and the negative electrode raw material are placed in a state where the active material layers are opposed to each other, and
It was sent out between book rolls and laminated to obtain a raw battery laminate. The obtained laminate raw material was heated at 90 ° C. for 3 minutes to polymerize the monomer, and the electrolyte components in the active material layer and the electrolyte layer were gelled to obtain a sheet having a polymer electrolyte.

[0037]

[Table 4] Electrolyte component Electrolyte PC: Propylene carbonate (manufactured by Mitsubishi Chemical Corporation) Supporting electrolyte LiClO ₄ (manufactured by Wako Pure Chemical Industries) Additive 1,6-Dioxaspiro [4,4] nonane-2,7-dione (hereinafter referred to as “ spiro ") (Aldrich) Monomer Photomer4050 Photomer4158 Polyethylene oxide resin having an acrylic group at the terminal (Henkel) Crosslinking initiator Trignox21 (Kakuyaku Aguso)

[0038]

(Table 5) (Composition) PC 78 parts LiClO ₄ 7 parts spiro 5 parts Photomer 4050 6.7 parts Photomer 4158 3.3 parts Trignox 21 1.0 parts

The above thin sheet was cut into an electrode size of 40 mm × 50 mm using a punching die. The positive electrode layer was partially cut using a rotary blade on the rectangular laminate obtained by the cutting. The part of the partial cutting was 1.0 mm from the cut end face of the punching die. The rotating blade uses a super hard metal saw and cutting speed 20
The cutting depth from the electrode substrate surface was feedback-controlled to 70 μm at 0 mm / min and a rotation speed of 1000 rpm.
After the partial cutting, the positive electrode material remaining on the end separator was removed by bonding to a tape. The positive electrode and the negative electrode are provided with terminals to be electrically connected to the electrode substrate, and sealed in a flexible vacuum pack to form a thin-layer lithium secondary battery.
0 pieces were created and evaluated. The evaluation was performed by counting the number of batteries in which a short circuit occurred after charge / discharge, and microscopic observation of the end face of the unit cell after charge / discharge. The results are shown in Table 1.

Comparative Example 1 Twenty thin-layer batteries were prepared and evaluated in the same manner as in Example 1 except that the positive electrode layer was not partially cut. The results are shown in Table 1.

[0041]

[Table 6]

[0042]

According to the present invention, by cutting a part of the electrode after laminating the electrode, it is possible to manufacture a battery with reduced short circuit and dendride generation with high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a preferred embodiment of the present invention.

FIG. 2A is a schematic perspective view showing a part of a sheet obtained after a cutting step, which is partially cut, and FIG. 2B is a schematic perspective view showing a unit cell obtained after a part is cut.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive raw material 2,5,8 Roll 3,6,9 Coater 4 Negative raw material 5 Separator raw material 12 Cutter 21,21 'Positive electrode 22 Negative electrode 23 Electrolyte layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Makoto Sato 370 Yenzo, Chigasaki-shi, Kanagawa F-term in Mitsubishi Chemical Engineering Corporation (reference) 5H029 AJ14 AK02 AK03 AK05 AK16 AK18 AL01 AL02 AL04 AL06 AL07 AL11 AL12 AM00 AM02 AM03 AM04 AM05 AM07 AM16 BJ04 BJ12 CJ04 CJ11 CJ22 DJ04 DJ07 HJ04

Claims (6)

[Claims] 1. A method for manufacturing a thin film battery comprising a positive electrode, a negative electrode and a gel electrolyte layer formed between them, comprising: (1) a positive electrode active material layer on a different long conductive support; And a negative electrode raw material forming step of forming a positive electrode raw material and a negative electrode raw material by forming a negative electrode active material layer and a negative electrode active material layer, respectively. (2) The positive electrode raw material and the negative electrode raw material are formed as an active material layer. (3) a battery having a positive electrode and a negative electrode by cutting the battery laminate raw material in a direction substantially perpendicular to the longitudinal direction to obtain a battery laminate raw material; A cutting step of obtaining a laminate, and (4) cutting at least a part of one electrode portion of the original battery laminate or the battery laminate before or after the cutting step;
A method for manufacturing a thin-film battery, comprising a partial cutting step of reducing the size of the one electrode compared to the other electrode. 2. The method according to claim 1, wherein in the partial cutting step, a position in a thickness direction of a cut portion from a reference position of the original battery stack or the battery stack is measured, and a cutting depth is controlled based on the result. 3. The method for producing a thin-film battery according to item 1. 3. A long separator raw material is interposed between the positive electrode raw material and the negative electrode raw material in the laminating step.
Or the manufacturing method of the thin film type battery as described in 2. 4. The method of manufacturing a thin-film battery according to claim 1, further comprising an electrolyte component holding step of holding an electrolyte component in each of the positive electrode raw material and the negative electrode raw material before the laminating step. Method. 5. The electrolyte component according to claim 4, wherein the electrolyte component contains a non-aqueous solvent, an electrolyte salt and a monomer, and after application, the monomer is polymerized into a polymer, and the non-aqueous solvent and the electrolyte salt are retained in the polymer. A method for manufacturing a thin-film battery. 6. The method according to claim 5, further comprising a polymerization step for polymerizing the monomer after the laminating step and before the cutting step and the partial cutting step.