JP2013218801A - Battery element structure manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a battery element structure.SOLUTION: The method comprises: a separator lamination step of laminating a separator 3 made of a nonwoven cloth 3a obtained by spinning from an active material layer side with an electro-spinning method on an electrode plate 10 having a belt-like metallic collector and an active material layer provided on one face side thereof. In the separator lamination step, a ground electrode 44 wider than the electrode plate 10 is arranged on the other face side of the metallic collector, and the metallic collector of the electrode plate 10 is electrically connected to the ground electrode 44. An insulation wall 45 is arranged on the ground electrode 44 on an outer side of a side end 10c of the electrode plate 10. A gap of 1-20 mm is preferably provided between the side end 10c of the electrode plate 10 and the insulation wall 45, and a gap of 0.01-10 mm is provided between the insulation wall 45 and the ground electrode 44. It is preferable that the insulation wall 45 is raised from the ground electrode 44.

Description

  The present invention relates to a method for producing a battery element structure. More specifically, the present invention relates to a method for producing a battery element structure including a separator made of a nonwoven fabric in which resin fibers spun by an electrospinning method are directly and efficiently deposited on an electrode plate.

  In recent years, with the reduction in size and cordlessness of various electronic devices, there has been an increasing demand for higher capacity and lighter weight of batteries used as power sources for driving them. Under such circumstances, secondary batteries, such as lithium ion secondary batteries, are attracting attention. This lithium ion secondary battery usually has a positive electrode and a negative electrode that are doped and dedoped with lithium ions, a separator interposed between the positive electrode and the negative electrode, and a lithium salt dissolved in an aprotic organic solvent. And a non-aqueous electrolyte solution impregnated in the separator. The electrode includes a current collector made of a metal foil and the like, and an active material layer formed on the surface of the current collector. The active material layer is usually an active material, a conductive agent, and these materials. And a binder that binds to the current collector.

  Furthermore, many of the separators currently used are made of a porous film made of a resin, for example, a porous film using a polyolefin resin such as polyethylene or polypropylene, and in addition, a laminate of such a porous film and a nonwoven fabric. A separator made of is also proposed. For example, a separator is known in which sheets made of a fiber assembly having a predetermined fiber diameter and fiber length are laminated on both surfaces of a mesh sheet surface (see, for example, Patent Document 1). And it is described that the sheet | seat which consists of this fiber assembly is formed in both surfaces of a mesh shaped sheet | seat by the electrospinning method.

A battery element having a separator made of a resin porous membrane and a fiber assembly formed by electrospinning as described in Patent Document 1 has a structure as shown in FIGS. That is, a separator S composed of a resin porous membrane P having a large number of through-holes P ₁ and a fiber assembly 3 c (nonwoven fabric) formed on the resin porous membrane P is formed between the positive electrode plate 11 and the negative electrode plate 12. Intervening between.

  There is also known a separator electrode integrated power storage element in which a separator made of a porous layer containing nanofibers formed by an electrospinning method is joined and integrated on the electrode surface (see, for example, Patent Document 2). It is described that an electrochemical element having a low internal resistance and a low internal short-circuit failure rate can be realized.

JP 2006-92829 A JP 2010-225809 A

  However, the porous film using a polyolefin resin or the like described in Patent Document 1 has low affinity with the electrolytic solution, and the retention of the electrolytic solution is not sufficient. Therefore, a lithium ion secondary battery using such a porous membrane as a separator has problems such as unstable power generation performance, insufficient strength of the separator, and limitations in increasing capacity. Moreover, although the separator described in Patent Document 2 may sufficiently function as a separator for a secondary battery, Cited Document 2 makes no mention of efficiently forming the separator on the electrode surface.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is a separator made of a nonwoven fabric in which resin fibers spun by an electrospinning method are directly and efficiently deposited on an electrode plate. It aims at providing the manufacturing method of a battery element structure provided with.

The present invention is as follows.
1. A band-shaped metal current collector,
An electrode plate comprising an active material layer provided on one side of the metal current collector,
A method for producing a battery element structure comprising a separator lamination step of laminating a separator made of a nonwoven fabric by spinning from the active material layer side by an electrospinning method,
In the separator lamination step, a ground electrode wider than the electrode plate is disposed on the other surface side of the metal current collector, and the metal current collector and the ground electrode are electrically connected,
An insulating wall is disposed on the ground electrode outside the side end of the electrode plate.
2. A gap of 1 to 20 mm is opened between the side end portion of the electrode plate and the insulating wall. The manufacturing method of the battery element structure described in 2.
3. A gap of 0.01 to 10 mm is provided between the insulating wall and the ground electrode, and the insulating wall is in a state of floating from the ground electrode. Or 2. The manufacturing method of the battery element structure described in 2.

In the electrospinning method, resin fibers are more easily spun on the exposed ground electrode than on the electrode plate provided with the active material layer. In the manufacturing method of this invention, the insulating wall is arrange | positioned in the part located in the outer side of the side edge part of an electrode plate among the exposed surfaces of an earth electrode. Therefore, spinning of the resin fiber is suppressed in the portion of the ground electrode where the insulating wall is disposed, and unnecessary nonwoven fabric can be prevented from being formed in this portion. As a result, resin fibers are efficiently deposited on the electrode plate, and separators made of nonwoven fabric are efficiently laminated. In addition, a separator with a more uniform thickness can be obtained, and since resin fibers are concentrated and deposited on the electrode plate, the time required for stacking the separators can be shortened.
In addition, when a gap of 1 to 20 mm is opened between the side edge of the electrode plate and the insulating wall, the ground electrode is exposed at the gap, and resin fibers are deposited on the exposed surface, A nonwoven fabric is formed. Thereby, a separator will also be laminated | stacked also on the side end surface of an electrode plate, and the short circuit in the side end part of an electrode plate can be prevented.
Furthermore, when a gap of 0.01 to 10 mm is opened between the insulating wall and the earth electrode, and the insulating wall is in a state of floating from the earth electrode, an electrode plate is placed on the earth electrode. When the electrode plate is transferred together with the ground electrode, the insulating wall and the ground electrode are not in contact with each other and can be transferred smoothly. If the gap is too large, the resin fibers may flow toward the gap and be deposited on the ground electrode. However, if the gap is 5 mm or less, such a problem can be suppressed.

It is a schematic diagram for demonstrating a mode that the separator which consists of a nonwoven fabric formed by the electrospinning method is laminated | stacked on the electrode plate on a ground electrode. It is a typical perspective view of the electrode plate in which the active material layer was provided in the one surface side of the metal electrical power collector. It is a schematic diagram of the cross section of a mode that the separator is laminated | stacked on the electrode plate of FIG. It is a typical perspective view for demonstrating the battery element structural body of this invention by which the separator which consists of a nonwoven fabric was laminated | stacked on the electrode plate. It is a schematic diagram for demonstrating the shape of an insulating wall. It is a schematic diagram for demonstrating the shape of an insulating wall. It is a schematic diagram for demonstrating the shape of an insulating wall. It is a schematic diagram for demonstrating the shape of an insulating wall. It is a typical perspective view for demonstrating the conventional battery element provided with the separator which consists of a resin-made porous membrane and the fiber assembly laminated | stacked on this resin-made porous membrane by the electrospinning method. It is typical sectional drawing in the location where the positive electrode plate of the battery element of FIG. 9 is not laminated | stacked.

Hereinafter, the present invention will be described in detail with reference to FIGS.
The items shown here are for illustrative purposes and exemplary embodiments of the present invention, and are the most effective and easy-to-understand explanations of the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this respect, it is not intended to illustrate the structural details of the present invention beyond what is necessary for a fundamental understanding of the present invention. It will be clear to those skilled in the art how it is actually implemented.

[1] Method for Producing Battery Element Constituent Comprising Separator Laminating Step The method for producing battery element constituting body 100 (see FIG. 4) of the present invention includes a strip-shaped metal current collector 10a and one surface of the metal current collector 10a A separator laminating step of laminating a separator 3 made of nonwoven fabric 3a by spinning from the active material layer 10b side by an electrospinning method to an electrode plate 10 (see FIG. 2) provided with an active material layer 10b provided on the side; (As shown in FIG. 1, the spun resin fibers are directly deposited on the electrode plate 10, and the separator 3 made of the nonwoven fabric 3a is laminated).

  In the separator lamination step, a ground electrode 44 wider than the electrode plate 10 is disposed on the other surface side of the metal current collector 10a, and the metal current collector 10a and the ground electrode 44 are electrically connected. An insulating wall 45 is disposed on the ground electrode 44 outside the side end portion 10 c of the electrode plate 10. In addition, when the electrode plate 10 is a positive electrode plate or a negative electrode plate, the separator 3 made of the nonwoven fabric 3a can be laminated in the same manner on each active material layer 10b side.

(1) Ground electrode and insulating wall The ground electrode 44 is wider than the electrode plate 10, and is on the other side of the metal current collector 10a provided on the electrode plate 10, that is, on the side opposite to the surface on which the active material layer 10b is provided. Placed on the surface. As a result, the metal current collector 10a and the ground electrode 44 come into contact with each other and are electrically connected. The ground electrode 44 is disposed such that the side portion thereof protrudes from the electrode plate 10 (see FIG. 3).

  By arranging so that the side portion of the ground electrode 44 protrudes from the electrode plate 10 and is exposed, the resin solution is discharged evenly in the width direction of the electrode plate 10 during spinning (the discharged resin in FIG. 1). See solution 3b). Thereby, the nonwoven fabric 3a which is more uniform in the width direction of the electrode plate 10 and has little variation in thickness, that is, the separator 3 can be laminated on the active material layer 10b. The form of the ground electrode 44 is not particularly limited, but it is a belt-like sheet or foil in order to be electrically connected by being placed on the other surface side of the belt-like metal current collector 10a and brought into contact therewith. Is preferred. Further, the material of the ground electrode 44 is not particularly limited as long as it has sufficient conductivity, but is preferably a metal. As the ground electrode 44, a metal sheet, a metal foil, or the like can be used. A foil or the like can be used.

  An insulating wall 45 is disposed on the ground electrode 44 exposed outside the side end portion 10 c of the electrode plate 10. The insulating wall 45 prevents the discharged resin solution from flowing in the direction of the highly conductive ground electrode 44 during electrospinning, so that resin fibers are not sufficiently deposited on the active material layer 10b having low conductivity. To do. Therefore, the insulating wall 45 may be made of a material having high electrical insulation, and a molded body made of synthetic resin, synthetic rubber, or the like can be used. Regardless of the type of the synthetic resin and the synthetic rubber, normally, the insulating material 45 is sufficiently higher in insulation than the active material layer 10 b, and a molded body using various synthetic resins and synthetic rubbers can be used as the insulating wall 45.

  The shape of the insulating wall 45 is not particularly limited. In order to prevent the discharged resin solution from flowing in the direction of the highly conductive ground electrode 44 exposed to the outside of the side end portion 10c of the electrode plate 10, the exposed portion of the ground electrode 44 is sufficiently covered. I can do it. As shown in FIG. 1, the insulating wall 45 may be a wall body that is disposed in the longitudinal direction on the exposed portion of the ground electrode 44 along the side end portion 10 c of the electrode plate 10. The shape of the insulating wall 45 is not particularly limited. For example, the insulating wall 45 has a substantially rectangular parallelepiped shape as shown in FIG. 1, a substantially cylindrical shape as shown in FIG. 5, a substantially rectangular tube shape as shown in FIG. A hollow cylindrical shape or a cylindrical shape obtained by hollowing out a truncated cone from a prism as shown in FIG.

Moreover, a side end portion 10c of the electrode plate 10, but may have no gap between the insulating wall 45, preferably a gap S ₁ is being opened as shown in FIG. If an appropriate gap is opened and the ground electrode 44 is exposed here, the discharged resin solution flows in the direction of the exposed highly conductive ground electrode 44. As a result, the resin fiber is deposited on the surface of the side end portion 10c of the electrode plate 10 and the separator 3 made of the nonwoven fabric 3a is laminated, thereby preventing a short circuit at the side end portion 10c of the electrode plate 10. The dimensions of the gap _{S 1} is not particularly limited, can be 1 to 20 mm, 2 to 15 mm, it is particularly preferably 5 to 10 mm.

Furthermore, between the insulating wall 45 and the ground electrode 44, as long as the transport of the ground electrode 44 is not hindered, or may be in contact, but is preferably a gap S ₂ are opened (see FIG. 3). It is opened gap S _2, if it is a state where the insulating wall 45 is floated from the ground electrode 44, damage due to rubbing between the insulating wall 45 and the ground electrode 44, and further can be prevented from being damaged. The dimensions of the clearance _{S 2} is not particularly limited, can be 0.01 to 10 mm, 0.01～8Mm, it is particularly preferably 0.01 to 5 mm. If the ground electrode 44 is a metal foil such as an aluminum foil or a metal sheet and the insulating wall 45 is a molded body using a synthetic resin or the like, it is easy to slip on each other, and the gap between the ground electrode 44 and the insulating wall 45 is 0. Even if it is as small as 0.01 mm, damage and breakage of the ground electrode 44 can be sufficiently prevented.

(2) Electrospinning method In the electrospinning method, a resin solution obtained by dissolving a spinnable resin in a solvent is discharged from a nozzle to an electrostatic field formed between electrodes to perform spinning. Then, the resin fiber is directly deposited on the electrode plate 10, whereby the separator 3 made of the nonwoven fabric 3a is laminated. Most of the solvent evaporates and evaporates until the resin solution reaches the electrode plate 10, but if necessary, spinning can be performed under an atmosphere in which the solvent is removed under heating and / or reduced pressure. .

  Examples of the method for discharging the resin solution to the electrostatic field include a method in which the resin solution is supplied from a container to a nozzle that opens to the electrostatic field and discharged. In this way, the resin can be made into a fiber by discharging the resin solution from a nozzle opened at a predetermined position of the electrostatic field and spinning the resin solution by an electric field. Further, the solution temperature at the time of discharging and spinning of the resin solution can be from room temperature (20 to 30 ° C.) to the boiling point of the solvent, and can be easily discharged and spun at room temperature. On the other hand, the relative humidity is not particularly limited, but may be 10 to 70%, and preferably 20 to 60%. Furthermore, the thickness of the nonwoven fabric 3a, that is, the separator 3, can be easily adjusted by the discharge amount of the resin solution, the transfer speed of the electrode plate, and the like.

  As shown in FIGS. 1 and 3, the electrostatic field is formed with the resin solution container 41 and the nozzle 42 side as the voltage application side and the electrode plate 10 as the ground side. The applied voltage is not particularly limited, but can be 5 to 50 kV, preferably 5 to 35 kV, particularly 10 to 25 kV. As the electrode on the voltage application side, the nozzle 42 itself can be used, or an electrode attached to the nozzle 42 or the like can be used. The electrode can be formed of an inorganic or organic material having conductivity, and in particular, a metal is often used. In addition, an electrode in which a conductive material is coated on the surface of a molded body made of an insulating material may be used.

Hereinafter, the method of depositing the nonwoven fabric 3a on the electrode plate 10 using the electrospinning apparatus 4 of FIGS.
The number of nozzles 42 is not particularly limited, and may be one or plural as shown in FIGS.

  Further, the inner diameter of the nozzle 42 is not particularly limited, and although it depends on the fiber diameter and the like, it can be 5 to 500 μm, preferably 5 to 200 μm, and particularly preferably 5 to 100 μm. When the inner diameter of the nozzle 42 is 5 to 500 μm, the resin solution can be supplied to the nozzle 42 at a sufficient speed, and the nonwoven fabric 3 a made of resin fibers having a predetermined diameter can be efficiently formed. The material of the nozzle 42 is not particularly limited and may be metal or non-metal, but a metal is preferable because it can be used as an electrode on the voltage application side as described above. In the case where the nozzle 42 is made of a non-metal, a conductive material such as a metal can be disposed inside and used as an electrode.

  Further, the resin solution in the resin solution container 41 is transferred from the resin solution container 41 to the nozzle 42 and supplied by a solution supply device, for example, a constant flow pump or the like (not shown). The resin solution is discharged from the opening of the nozzle 42, and the spun resin fibers are directly deposited on the electrode plate 10 to form the nonwoven fabric 3 a, thereby forming the separator 3.

  The distance between the opening of the nozzle 42 and the electrode plate 10 is preferably set based on the charge amount, the inner diameter of the nozzle, the concentration of the resin solution, the discharge amount of the resin solution, and the like. For example, when the applied voltage is about 10 kV, the distance can be 50 to 200 mm. Furthermore, as described above, the applied electrostatic potential can be 5 to 50 kV, preferably 5 to 35 kV, and more preferably 10 to 25 kV. This potential can be set based on a known technique.

  Further, the solvent used for the resin solution is vaporized and evaporated according to conditions while the resin solution is discharged toward the electrode plate 10 and being spun, and the resin fibers are spun to form the nonwoven fabric 3a. The In this step, when the atmospheric temperature is, for example, room temperature (20 to 30 ° C.), generally, the solvent is evaporated in the whole amount until the resin solution reaches the electrode plate 10. However, when the transpiration of the solvent is insufficient, the nonwoven fabric 3a can be formed under heating and / or under reduced pressure. The ambient temperature may be room temperature (20 to 30 ° C.) depending on the viscosity of the resin solution, the type of solvent, etc., and it is sufficient to raise the temperature to about 50 ° C. even when heating.

  Furthermore, in the manufacturing method of the battery element structure of the present invention, the spun resin fibers are directly deposited on the electrode plate 10 to form the nonwoven fabric 3a, which becomes the separator 3. In this case, the spun resin fibers may be directly deposited on one surface of the electrode plate 10 on which the active material layer 10b is provided to form the nonwoven fabric 3a (see FIGS. 1 and 3). The nonwoven fabric 3a may be formed by directly depositing resin fibers. When the nonwoven fabric 3a is formed on both surfaces of the electrode plate 10, the active material layer 10b is usually provided on both surfaces of the electrode plate 10, but may be provided only on one surface.

(3) Electrode Plate As the “electrode plate 10”, there are a positive electrode plate and a negative electrode plate, and each electrode plate 10 usually binds a band-shaped metal current collector 10a, an active material, and an active material. And a binding resin for forming the active material layer 10b on the surface of the metal current collector 10a (see the electrode plate 10 in FIG. 2).

  As the metal current collector 10a, a material excellent in oxidation resistance is used for the positive electrode, and a material excellent in reduction resistance is used for the negative electrode. As the metal current collector 10a for the positive electrode, for example, aluminum, stainless steel or the like is used, and as the metal current collector 10a for the negative electrode, for example, copper, nickel, stainless steel or the like is used. Further, the metal current collector 10a has a strip shape, and the form thereof is not particularly limited, and examples thereof include a foil and a mesh. An aluminum foil is often used for the positive electrode, and a copper foil is often used for the negative electrode. Furthermore, although the thickness of the metal current collector 10a is not particularly limited, it can be 5 to 30 μm for both the positive electrode and the negative electrode, and is preferably 5 to 20 μm, particularly 7 to 15 μm.

The active material is not particularly limited, and a known active material can be used depending on the type of battery. For example, in the case of a lithium ion secondary battery, various lithium-containing transition metal oxides can be used as the positive electrode active material. Examples of the lithium-containing transition metal oxide include LiCoO ₂ , LiNiO ₂ , LiNiCoO ₂ , LiMn ₂ O _{4 and the} like. Further, as the negative electrode active material, a carbon material that can be doped / undoped with lithium ions can be used. Examples of the carbon material include materials obtained by sintering a resin such as polyacrylonitrile, a phenol resin, a phenol novolac resin, and cellulose, and artificial graphite and natural graphite. As this negative electrode active material, lithium titanate, a lithium alloy, or the like can be used. Although the thickness of the active material layer 10b to be formed is not particularly limited, both the positive electrode and the negative electrode active material layer 10b can be 10 to 50 μm, particularly 15 to 35 μm.

  Further, the positive electrode preferably contains a conductive auxiliary such as artificial graphite or nickel powder. In this case, although content of a conductive support agent is not specifically limited, When a positive electrode active material is 100 mass parts, it can be 10 mass parts or less, Especially 5-10 mass parts. On the other hand, although it is not necessary to contain a conductive support agent in a negative electrode, you may make it contain.

  In addition, as the binding resin, polyvinylidene fluoride, a fluorocopolymer of vinylidene fluoride and hexafluoropropylene, perfluoromethyl vinyl ether, tetrafluoroethylene, etc., and a fluororesin such as polytetrafluoroethylene, styrene- In addition to styrene copolymer resins such as butadiene copolymer and styrene-acrylonitrile copolymer, carboxymethyl cellulose, polyimide, and the like can be used. These binding resins may be used alone or in combination of two or more. Although the usage-amount of binder resin is not specifically limited, When a positive electrode active material and a negative electrode active material are 100 mass parts, it can be set as 3-30 mass parts, especially 7-25 mass parts.

(4) Resins used for spinning Resins that can be spun are not particularly limited. Examples of the resin include polyacrylonitrile, polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene succinate, polyethylene, polypropylene, polyvinylidene fluoride, polyhexafluoropropylene, polyethylene oxide, and polypropylene. Examples thereof include oxide, polyvinylidene chloride, cellulose, carboxymethyl cellulose and the like. Further, as the resin, polyacrylonitrile, polyethylene terephthalate, polypropylene or the like is preferable. Further, these resins may be used alone or in combination of two or more if a common good solvent is present.

  Also, the solvent for dissolving the resin is not particularly limited, but the resin can be sufficiently dissolved, and can be easily vaporized and evaporated while the resin solution is discharged and reaches the electrode plate. Solvents that do not remain in the resin fibers are preferable. Examples of such solvents include N, N-dimethylformamide, N, N-dimethylacetamide, methylene chloride, chloroform, carbon tetrachloride, cyclohexane, benzene, toluene, acetone, methyl ethyl ketone, methanol, ethanol, isopropanol, tetrahydrofuran, Examples include cyclohexanone, pyridine, acetonitrile, N-methylpyrrolidone and the like. As the solvent, a polar solvent is preferable, and an amide solvent such as N, N-dimethylformamide is particularly preferable. These solvents may be used alone or in combination of two or more.

  The resin content in the resin solution is also not particularly limited. However, when the resin solution is 100% by mass, the resin content can be 2 to 20% by mass, 4 to 15% by mass, particularly 6 to 10%. It is preferable that it is mass%. If the resin content is 2 to 20% by mass, a resin fiber having a predetermined diameter and a required amount can be easily formed. Further, when the content is too high, the solution viscosity is increased, the resin solution is hardly discharged, and spinning is not difficult.

The thickness of the nonwoven fabric 3a used as the separator 3 is not specifically limited, It can be 10-50 micrometers, It is preferable that it is 10-40 micrometers, especially 15-35 micrometers. Furthermore, the diameter of the resin fiber which comprises the nonwoven fabric 3a is not specifically limited, What is necessary is just 100-1000 nm, and it is preferable that it is 150-800 nm, especially 250-600 nm. Also, the basis weight of the nonwoven fabric 3a is not particularly limited, may be a 1 to 10 g / ^{m 2,} 1 to 6 g / ^{m 2,} it is particularly preferably 2-5 g / ^{m 2.} In addition, a fiber diameter observes the multiple places (for example, 10 places) of the nonwoven fabric 3a with an optical microscope, measures the diameter of the multiple (for example, 10) resin fibers in each visual field, and calculates an average value. Can be obtained.

The porosity of the nonwoven fabric 3a to be the separator 3 is not particularly limited, and can be 50 to 85%. It is preferably 55 to 85%, particularly 60 to 80%, and more preferably 65 to 80%. When the porosity is 50 to 85%, particularly 65 to 80%, the separator 3 having sufficient strength and high ion conductivity can be obtained. The porosity can be calculated based on the following formula.
Porosity (%) = 100− {weight per unit / (density of resin used for forming nonwoven fabric 3a × thickness of nonwoven fabric)} × 100
(However, the basis weight of the nonwoven fabric 3a is g / m ² , the resin density is g / cm ³ , and the thickness of the nonwoven fabric 3a is μm)

[2] Battery The battery element structure produced by the method of the present invention is useful for a battery element of a secondary battery, particularly a lithium ion secondary battery. Hereinafter, a lithium ion secondary battery will be described as an example of the battery. .
As described above, the electrode plate 10 usually includes a metal current collector 10a, an active material, and a binding resin for binding the active material to form the active material layer 10b on the surface of the current collector. Have.

  Various lithium salts are used as the electrolyte impregnated in the separator 3. Examples of the lithium salt include lithium perchlorate, lithium hexafluorophosphate, lithium borofluoride, lithium hexafluoroarsenate, lithium trifluorosulfonate, lithium perfluoromethylsulfonylimide, lithium perfluoroethylsulfonylimide, and the like. It is done. These lithium salts may be used alone or in combination of two or more.

  Various lithium salts that are electrolytes are usually dissolved in a non-aqueous solvent and used as a non-aqueous electrolyte. As the non-aqueous solvent, a polar organic solvent having 10 or less carbon atoms generally used in lithium ion secondary batteries can be used without particular limitation. Examples of the polar organic solvent include propylene carbonate, ethylene, and the like. Examples thereof include carbonate, butylene carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, sulfolane, acetonitrile, and a mixed solvent in which these solvents are mixed. The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.2 to 2 molar.

  For example, when the battery is a lithium ion secondary battery, the battery element in which the positive electrode plate 11 and the negative electrode plate 12 are laminated via the separator 3 is accommodated in the exterior material, and a non-aqueous electrolyte is injected. Then, it can be manufactured by sealing the opening. Moreover, the injection method of the non-aqueous electrolyte is preferably a vacuum injection method, but is not particularly limited to this method. Furthermore, the battery element before being housed in the exterior material may be pre-impregnated with the non-aqueous electrolyte solution, and after storing the battery element impregnated with the non-aqueous electrolyte solution in the exterior material, if necessary A non-aqueous electrolyte may be injected.

  In a so-called film-clad battery using a flexible laminated material such as an aluminum laminate film as the exterior material, the electrode plate 10 and the separator 3 are preferably bonded and integrated. In this case, the electrode plate 10 and the separator 3 are usually fused by thermocompression bonding. However, in the battery element structure manufactured by the method of the present invention, the nonwoven fabric 3a to be the separator 3 is electroded by electrospinning. It is formed directly on the plate 10, and the electrode plate 10 and the separator 3 are integrated sufficiently firmly. Therefore, it is not particularly necessary to perform thermocompression bonding, but it is also possible to perform thermocompression bonding and integrate more firmly.

  Furthermore, the exterior material is not particularly limited, and examples thereof include a steel can, an aluminum can, and the like in addition to the above-described flexible laminated material such as an aluminum laminate film. Also, the external shape of the lithium ion secondary battery is not particularly limited, and may be determined by the type of exterior material, but it is a flat type such as a cylindrical type or a square type (see batteries 81 and 82 in FIG. 6), a button type, or the like. There are many cases.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
1 and 3, the resin fibers were deposited on the electrode plate 10, and the separator 3 made of the nonwoven fabric 3a was laminated.
As the electrode plate 10, a negative electrode plate 12 having a width of 56 mm was used in which artificial graphite was bound as an active material to a copper foil (metal current collector 10 a) (an active material layer 10 b was formed). Moreover, as the resin solution, a dimethylformamide solution of polyacrylonitrile (the content of the resin is 6.0% by mass when the solution is 100% by mass) was used. Furthermore, a voltage of 20 kV was applied with the nozzle 42 side as the voltage application side and the negative electrode plate 12 side as the ground side, thereby forming an electrostatic field.

  In addition, a ground electrode 44 made of an aluminum foil having a width of 200 mm was disposed on the lower surface of the copper foil of the negative electrode plate 12 so that the center lines of the respective longitudinal directions coincided with each other. As a result, the ground electrode 44 was exposed on both sides of the negative electrode plate 12 in the width direction. Thereafter, an insulating wall 45 made of synthetic resin was disposed on the ground electrode 44 and on the side of the nozzle 42. A 10 mm gap was formed between the side edge of the negative electrode plate 12 and the insulating wall 45, and a 5 mm gap was formed between the bottom surface of the insulating wall 45 and the surface of the ground electrode 44. In this way, the negative electrode plate 12 and the ground electrode 44 are transferred, and the spun resin fibers are directly deposited on the negative electrode plate 12. As a result, the nonwoven fabric 3a is made of fibers having an average diameter of 250 nm and has a thickness of 25 μm. Separator 3 was laminated.

  In the present embodiment, the insulating wall 45 is disposed on the exposed surface of the ground electrode 44 at a portion located outside the side end portion of the electrode plate 10. Therefore, in the portion of the ground electrode 44 where the insulating wall 45 is disposed, the spinning of the resin fiber is suppressed, and it is possible to prevent unnecessary nonwoven fabric 3a from being formed in this portion. As a result, the resin fibers were efficiently deposited on the electrode plate, and the separator 3 made of the nonwoven fabric 3a was efficiently laminated. In addition, the separator 3 having a more uniform thickness can be obtained, and the resin fibers are concentrated and deposited on the electrode plate 10, so that the time required for stacking the separators 3 can be shortened.

  Furthermore, since the separator 3 having a more uniform thickness was formed, the stress concentration due to the non-uniform thickness was eliminated, and the strength of the separator 3 was higher than the conventional one. Thus, since the strength of the separator 3 can be increased without increasing the thickness of the separator 3, it is expected that the adverse effect of increasing the thickness of the separator 3 will be reduced. That is, by increasing the thickness of the separator 3, there is little problem that the ion conductivity is lowered and the energy density is lowered. Furthermore, it is not necessary to use a resin porous membrane having low ion conductivity for the purpose of reinforcing the separator 3 or the like.

  It should be noted that the above description is for illustrative purposes only and is not to be construed as limiting the invention. Although the invention has been described with reference to exemplary embodiments, it is to be understood that the language used in the description and illustration of the invention is illustrative and exemplary rather than restrictive. As detailed herein, modifications may be made in the embodiments within the scope of the appended claims without departing from the scope or spirit of the invention. Although specific structures, materials, and embodiments have been referred to in the detailed description of the invention herein, it is not intended to limit the invention to the disclosure herein, but rather, the invention is claimed. It covers all functionally equivalent structures, methods and uses within the scope.

  The present invention can be used in the technical field of batteries, in particular, secondary batteries such as lithium ion secondary batteries.

DESCRIPTION OF SYMBOLS 100; Battery element structural body, 10; Electrode plate, 10a; Metal collector, 10b; Active material layer, 10c; Side edge part of electrode plate, 3; Separator, 3a; Nonwoven fabric, 3b; 3c; Fiber assembly, 4; Electrospinning device, 41; Resin solution container, 42; Nozzle, 43; High voltage generator, 44; Earth electrode, 45; Insulating wall, P: Resin porous membrane, P ₁ ; Through hole, S; separator.

Claims (3)

A band-shaped metal current collector,
An electrode plate comprising an active material layer provided on one side of the metal current collector,
A method for producing a battery element structure comprising a separator lamination step of laminating a separator made of a nonwoven fabric by spinning from the active material layer side by an electrospinning method,
In the separator lamination step, a ground electrode wider than the electrode plate is disposed on the other surface side of the metal current collector, and the metal current collector and the ground electrode are electrically connected,
An insulating wall is disposed on the ground electrode outside the side end of the electrode plate.   The manufacturing method of the battery element structure according to claim 1, wherein a gap of 1 to 20 mm is opened between a side end portion of the electrode plate and the insulating wall. A gap of 0.01 to 10 mm is opened between the insulating wall and the ground electrode,
The method of manufacturing a battery element assembly according to claim 1, wherein the insulating wall is in a state of being floated from the ground electrode.

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