Method of producing electrode assembly for nonaqueous electrolyte secondary battery, electrode assembly, and battery

Abstract

To provide an electrode assembly for a nonaqueous electrolyte secondary battery that can exhibit electrode assembly formability as well as liquid-injection characteristics and liquid-impregnation characteristics of an electrolytic solution, and a method of producing the same.SOLUTION: There is provided a method of producing an electrode assembly for a nonaqueous electrolyte secondary battery, which includes: a preparation step of preparing a positive electrode plate, a negative electrode plate, and a separator, the separator including a base material and an adhesive layer that is placed on at least one side of the base material and that includes an adhesive resin; a stacking step of obtaining a stack including the positive electrode plate, the separator, and the negative electrode plate, while the adhesive layer of the separator is placed in contact with at least one of the positive electrode plate and the negative electrode plate; and a pressing step of pressing the stack at a temperature not higher than a glass transition point of the adhesion resin and at a pressure from 8 to 20 MPa to obtain an electrode assembly for a nonaqueous electrolyte secondary battery. An area ratio of the adhesive layer to the base material in a plan view of the separator is from 10 to 70%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for producing an electrode body for a non-aqueous electrolyte secondary battery, and further to an electrode body for a non-aqueous electrolyte secondary battery and a non-aqueous electrolyte secondary battery including the same. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2011-54502 (Patent Document 1) discloses a lithium-ion secondary battery in which a separator having an adhesive resin that exhibits adhesiveness when heated and an adhesive resin is present on at least one side of the substrate, and at least one of a positive electrode and a negative electrode are integrated with the adhesive resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-54502 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, since hot pressing is performed at a relatively high temperature (temperature 60 to 120°C), the adhesion between the electrode plate and the separator is high and the formability of the electrode body is improved, but the adhesion between the electrode plate and the separator becomes too high, and the impregnation of the nonaqueous electrolyte between the electrode plate and the separator may decrease in the process of manufacturing a nonaqueous electrolyte secondary battery (hereinafter also referred to as a battery). In addition, when the base material in the separator includes a porous film, the laminate is pressed at a relatively high temperature, so that the voids in the porous film are crushed, and the impregnation of the nonaqueous electrolyte into the inside of the separator may decrease.

[0005] An object of the present disclosure is to provide an electrode body for a non-aqueous electrolyte secondary battery, which is capable of satisfying both the formability of the electrode body and the injectability and impregnation ability of a non-aqueous electrolyte, and a method for producing the same. [Means for solving the problem]

[0006] The present invention provides the following method for producing an electrode assembly for a non-aqueous electrolyte secondary battery (hereinafter also referred to as an electrode assembly), an electrode assembly, and a battery. [1] A method for producing an electrode body for a non-aqueous electrolyte secondary battery, comprising the steps of: A preparation step of preparing a positive electrode plate, a negative electrode plate, a separator having a substrate and an adhesive layer containing an adhesive resin on at least one side of the substrate; a lamination step of placing the adhesive layer of the separator in contact with at least one of the positive electrode plate and the negative electrode plate to obtain a laminate including the positive electrode plate, the separator, and the negative electrode plate; a pressing step of pressing the laminate at a temperature equal to or lower than the glass transition point of the adhesive resin and at a pressure of 8 to 20 MPa to obtain an electrode body for a non-aqueous electrolyte secondary battery; Including, The method for producing an electrode assembly for a non-aqueous electrolyte secondary battery, wherein, in a plan view of the separator, an area ratio of the adhesive layer to the base material is 10 to 70%. [2] The method for producing an electrode assembly for a non-aqueous electrolyte secondary battery according to [1], wherein the substrate includes a porous film. [3] The method for producing an electrode body for a nonaqueous electrolyte secondary battery according to [1] or [2], wherein the temperature at which the laminate is pressed in the pressing step is 15 to 35°C. [4] The method for producing an electrode body for a nonaqueous electrolyte secondary battery according to any one of [1] to [3], wherein in the pressing step, the laminate is pressed for a time of 3 seconds or more and less than 30 seconds. [5] The method for producing an electrode body for a nonaqueous electrolyte secondary battery according to any one of [1] to [4], wherein the separator further comprises a heat-resistant layer, and in the lamination step, the separator is disposed so that the heat-resistant layer side faces the positive electrode plate. [6] An electrode assembly for a non-aqueous electrolyte secondary battery comprising a positive electrode plate, a separator, and a negative electrode plate, The separator includes a substrate including a porous film and an adhesive layer including an adhesive resin on at least one side of the substrate, In a plan view of the separator, an area ratio of the adhesive layer to the base material is 10 to 70%; At least one of the positive electrode plate and the negative electrode plate is disposed in contact with the adhesive layer, the adhesion strength between the substrate and at least one of the positive electrode plate and the negative electrode plate arranged in contact with the adhesive layer is 0.2 to 5.0 kN / m; the porous film has a porosity in a portion facing both a positive electrode active material-coated portion and a negative electrode active material-coated portion, and a porosity in a portion not facing at least one of the positive electrode active material and the negative electrode active material, the difference being 8.0% or less. [7] The electrode body for a nonaqueous electrolyte secondary battery according to [6], wherein the adhesive resin has a glass transition point of more than 35° C. [8] The separator further comprises a heat-resistant layer; 13. The electrode assembly for a non-aqueous electrolyte secondary battery according to claim 1, [6] or [7], wherein the separator is disposed so that the heat-resistant layer side faces the positive electrode plate. [9] A non-aqueous electrolyte secondary battery comprising the electrode body for a non-aqueous electrolyte secondary battery according to any one of [6] to [8]. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an electrode body for a non-aqueous electrolyte secondary battery, which is capable of satisfying both the formability of the electrode body and the injectability and liquid-containing property of a non-aqueous electrolyte, and a method for producing the same. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic flow chart showing a method for manufacturing an electrode assembly. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of a laminate. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing an example of a layer structure of a cylindrically wound laminate. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an example of a layer structure of an assembly laminate of laminates. [Diagram 5] FIG. 5 is a schematic diagram showing an example of the configuration of a wound type electrode body. [Figure 6]FIG. 6 is a schematic diagram showing an example of the configuration of a laminated electrode body. [Figure 7] FIG. 7 is a schematic diagram showing an example of the configuration of a nonaqueous electrolyte secondary battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment. In all of the drawings, the scale of each component is appropriately adjusted to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

[0010] In this specification, elements expressed in the singular form include the plural form unless otherwise specified. For example, a "particle" can mean not only "one particle" but also "an aggregate of particles (powder, powder, particle group)."

[0011] <Method of manufacturing electrode body for non-aqueous electrolyte secondary battery> The manufacturing method of the electrode assembly of the present disclosure includes a preparation step (A), a lamination step (B), and a pressing step (C) as shown in Fig. 1. In the preparation step (A), a positive electrode plate, a negative electrode plate, and a separator are prepared. The positive electrode plate, the negative electrode plate, and the separator are described later.

[0012] In the lamination step (B), the adhesive layer of the separator is arranged in contact with at least one of the positive and negative electrodes to obtain a laminate including the positive and negative electrodes. By arranging the adhesive layer of the separator in contact with at least one of the positive and negative electrodes, the adhesive strength between the separator and at least one of the positive and negative electrodes is improved, and the formability of the electrode body tends to be improved.

[0013] In the lamination step (B), at least a part of the separator is interposed between the positive electrode plate and the negative electrode plate to separate the positive electrode plate and the negative electrode plate. FIG. 2 shows an example of the layer structure of the laminate. The laminate 40 shown in FIG. 2 includes a positive electrode plate 10, a negative electrode plate 20, and a separator 30. At least a part of the separator 30 is interposed between the positive electrode plate 10 and the negative electrode plate 20. The separator 30 separates the positive electrode plate 10 and the negative electrode plate 20. At least one of the positive electrode plate 10 and the negative electrode plate 20 is bonded to the separator 30. The separator 30 may have an adhesive layer described later on one side or both sides. When the separator 30 has an adhesive layer described later, the positive electrode plate 10 and the negative electrode plate 20 can each be bonded to the separator 30 via an adhesive layer. The positive electrode plate, the negative electrode plate, and the separator may all have a rectangular planar shape in a plan view, or may be strip-shaped. The plan view of the positive electrode plate, the negative electrode plate, and the separator refers to a view from the thickness direction (the D-axis direction in FIG. 2).

[0014] 2, the laminate 40 may include two separators 30. The laminate 40 may include a single separator 30. For example, a positive electrode plate 10 may be sandwiched between two separators 30. For example, a negative electrode plate 20 may be sandwiched between two separators 30. The laminate 40 may be formed by stacking, for example, a separator 30 (first separator), a negative electrode plate 20, a separator 30 (second separator), and a positive electrode plate 10 in this order.

[0015] When the electrode body is a wound type described later, the laminate 40 can be wound in a spiral shape. For example, by winding the laminate around a cylindrical winding core, a cylindrical wound body 41 can be formed as shown in FIG.

[0016] When the electrode body is a laminate type described below, it is possible to laminate a plurality of laminates 40. By laminating a plurality of laminates 40, an assembled laminate 42 can be formed as shown in FIG.

[0017] In the pressing step (C), the laminate is pressed at a temperature below the glass transition temperature of the adhesive resin and at a pressure of 8 to 20 MPa to obtain an electrode body for a non-aqueous electrolyte secondary battery. By pressing the laminate at a temperature and pressure within the above range, the adhesion between the electrode plate and the separator becomes appropriate in the manufacturing process of the non-aqueous electrolyte secondary battery, and the impregnation of the non-aqueous electrolyte tends to be easily improved. In addition, when the base material in the separator includes a porous film, the voids are not easily crushed, the decrease in the impregnation of the non-aqueous electrolyte into the separator is suppressed, and the injection and impregnation of the non-aqueous electrolyte tend to be easily improved. In this specification, the pressure in the pressing step (C) is the pressure (surface pressure) applied to the surface of the laminate to be pressed.

[0018] The temperature at which the laminate is pressed may be, for example, 0 to 60° C., more preferably 10 to 40° C., and even more preferably 15 to 35° C. The time for which the laminate is pressed may be, for example, 1 second or more and less than 60 seconds, 3 to 30 seconds, and even more preferably 3 to 20 seconds.

[0019] When the electrode body is a wound type, the above-mentioned cylindrical wound body 41 is pressed in the radial direction to form a flat electrode body 50 as shown in Fig. 5. When the electrode body is a laminated type, the above-mentioned assembled laminate 42 is pressed to form a laminated electrode body 50 as shown in Fig. 6.

[0020] In a plan view of the separator, the area ratio of the adhesive layer to the substrate in the separator (hereinafter also referred to as the adhesive layer area ratio) is 10 to 70%. When the adhesive layer area ratio is in the above range, the adhesion between the electrode plate and the separator becomes appropriate, and the injectability and impregnation property of the non-aqueous electrolyte tend to be easily improved. From the viewpoint of the injectability and impregnation property of the non-aqueous electrolyte, the adhesive layer area ratio is preferably 10 to 60%. The adhesive layer area ratio is determined by the method described in the Examples section below.

[0021] The adhesive layer area ratio can be set within the above range, for example, by adjusting the type and number of the coating arrangement pattern of the adhesive layer present on the substrate. The coating arrangement pattern can be, for example, a pattern (stripe pattern) in which the adhesive resin is formed and the adhesive resin is not formed alternately in a groove shape, or a pattern (dot pattern) in which the adhesive resin is formed in a plurality of discontinuous circular shapes. These coating arrangement patterns may be arranged regularly or randomly.

[0022] The positive electrode plate includes a positive electrode collector and a positive electrode active material layer. The positive electrode plate may include a positive electrode active material layer on one side or both sides of the positive electrode collector. The positive electrode collector may be a sheet or foil made of a metal such as aluminum, nickel, titanium, or stainless steel, and is preferably an aluminum foil. When an aluminum foil is used as the positive electrode collector, its thickness may be, for example, 5 μm or more and 35 μm or less, and preferably 7 μm or more and 20 μm or less.

[0023] The positive electrode active material layer contains a positive electrode active material. The positive electrode active material is not particularly limited, and one or more of those generally used as positive electrode active materials for lithium ion secondary batteries can be used. For example, lithium composite oxides, lithium transition metal phosphate compounds (e.g., LiFePO4), etc. can be preferably used. Examples of lithium composite oxides include lithium nickel composite oxides, lithium cobalt composite oxides, lithium manganese composite oxides, and lithium nickel manganese composite oxides (e.g., LiNi 0.5 Mn 1.5 O4), lithium nickel manganese cobalt complex oxides (e.g. LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2) etc.

[0024] The positive electrode active material may be positive electrode active material particles. The average particle size of the positive electrode active material particles is not particularly limited, but may be generally 0.5 μm to 50 μm, typically 1 μm to 20 μm.

[0025] The positive electrode active material layer may contain a material other than the positive electrode active material, such as a conductive material or a binder. As the conductive material, for example, carbon black such as acetylene black (AB) or other carbon materials (such as graphite) can be preferably used. As the binder, for example, fluorine-based binders such as polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE) or rubber-based binders such as styrene butadiene rubber (SBR) can be preferably used. In addition, the positive electrode active material layer may contain materials other than those described above (for example, various additives, etc.) as long as the effect of the present invention is not impaired.

[0026] The content of the positive electrode active material in the positive electrode active material layer (i.e., the ratio of the positive electrode active material to the total mass of the positive electrode active material layer) is preferably about 70 mass% or more from the viewpoint of energy density. For example, it is more preferably 75 mass% to 99 mass%, and even more preferably 80 mass% to 97 mass%. The content of the conductive material in the positive electrode active material layer is preferably, for example, 0.1 mass% to 20 mass%, and more preferably 1 mass% to 15 mass%. The content of the binder in the positive electrode active material layer is preferably, for example, 0.5 mass% to 15 mass%, and more preferably 1 mass% to 10 mass%. In addition, when various additives such as a thickener are contained, the content of the additive in the positive electrode active material layer is, for example, preferably 7 mass% or less, and more preferably 5 mass% or less.

[0027] The positive electrode plate can be produced, for example, by applying a positive electrode slurry containing a positive electrode active material, a binder, and an arbitrary amount of a dispersion medium onto a positive electrode current collector, drying the slurry, and then compressing the slurry. The positive electrode plate can be cut to a predetermined planar size according to the electrode specifications.

[0028] The negative electrode plate includes a negative electrode collector and a negative electrode active material layer. The negative electrode plate may include a negative electrode active material layer on one side or both sides of the negative electrode collector. The negative electrode collector may be, for example, a sheet or foil made of a metal with good electrical conductivity, such as copper, nickel, titanium, stainless steel, etc. The negative electrode collector is preferably a copper foil. The dimensions are not particularly limited and may be appropriately determined according to the battery design. When copper foil is used, the thickness may be, for example, 5 μm or more and 35 μm or less, and preferably 7 μm or more and 20 μm or less.

[0029] The negative electrode active material layer includes a negative electrode active material. As the negative electrode active material, for example, a carbon material such as graphite, hard carbon, soft carbon, etc. can be used. The graphite may be natural graphite or artificial graphite, or may be amorphous carbon-coated graphite in which graphite is coated with an amorphous carbon material.

[0030] The negative electrode active material may be negative electrode active material particles. The average particle size of the negative electrode active material particles is not particularly limited, but is, for example, 0.1 μm to 50 μm, preferably 1 μm to 25 μm, and more preferably 5 μm to 20 μm.

[0031] The negative electrode active material layer may contain components other than the negative electrode active material, such as a binder, a thickener, etc. As the binder, for example, styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), etc. may be used. As the thickener, for example, carboxymethyl cellulose (CMC), etc. may be used.

[0032] The thickness of the negative electrode active material layer is not particularly limited, but may be, for example, 10 μm to 300 μm, and preferably 20 μm to 200 μm. The content of the negative electrode active material in the negative electrode active material layer is preferably 90 mass% or more, and more preferably 95 mass% to 99 mass%. The content of the binder in the negative electrode active material layer is preferably 0.1 mass% to 8 mass% and more preferably 0.5 mass% to 3 mass%. The content of the thickener in the negative electrode active material layer is preferably 0.3 mass% to 3 mass% and more preferably 0.5 mass% to 2 mass%.

[0033] The negative electrode plate can be produced, for example, by applying a negative electrode slurry containing a negative electrode active material, a binder, and an arbitrary amount of a dispersion medium onto a negative electrode current collector, drying the slurry, and then compressing the slurry. The negative electrode plate can be cut to a predetermined planar size according to the electrode specifications.

[0034] The separator includes a substrate and an adhesive layer including an adhesive resin on at least one side of the substrate. The separator is interposed between the positive electrode plate and the negative electrode plate and can separate the positive electrode plate and the negative electrode plate. The separator is electrically insulating.

[0035] The substrate may include a porous film. The substrate may be, for example, substantially composed of a porous film. The porous film may be a resin film. The resin film may contain, for example, polyolefin or the like. The resin film may contain, for example, at least one selected from the group consisting of polyethylene (PE) and polypropylene (PP). The substrate may have, for example, a single-layer structure. The substrate may be, for example, substantially composed of a PE layer. The substrate may have, for example, a multi-layer structure. The substrate may be formed by laminating, for example, a PP layer, a PE layer, and a PP layer in this order. The resin film may have, for example, a thickness of 3 to 50 μm, may have a thickness of 3 to 30 μm, or may have a thickness of 5 to 15 μm.

[0036] The separator has an adhesive layer on one or both sides of the substrate. The adhesive layer can bond at least one of the positive and negative plates to the separator (substrate) by, for example, press molding. The adhesive layer includes an adhesive resin. The glass transition point of the adhesive resin may be, for example, above 35°C, and may be 40°C or higher or 50°C or higher. The glass transition point of the adhesive resin may be, for example, 70°C or lower or 60°C or lower, and may be 80°C or lower. Examples of the adhesive resin include resin particles such as fluorine-based resin, acrylic resin, urethane resin, ethylene vinyl acetate resin, and epoxy resin. Examples of the fluorine-based resin include polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), and the like.

[0037] The separator may further include a heat-resistant layer. The heat-resistant layer may have a function of suppressing the shrinkage of the separator due to heat during charging and discharging of the battery. The heat-resistant layer may include, for example, inorganic particles and a binder. The inorganic particles include, for example, ceramic particles such as alumina, boehmite, aluminum hydroxide, silica, titania, etc. As the binder, the resin material as described above as the constituent material of the adhesive layer may be appropriately used. In the heat-resistant layer, the mixing ratio (mass ratio) of the inorganic particles and the binder is preferably 98:2 to 50:50, more preferably 95:5 to 70:30. The thickness of the heat-resistant layer may be, for example, 1 to 10 μm, or 1 to 5 μm. The heat-resistant layer may be disposed on one side or both sides of the substrate. The heat-resistant layer is preferably disposed on the side of the separator facing the positive electrode plate. When the separator includes a heat-resistant layer, the separator may be disposed directly on the substrate, or may be disposed between the substrate and the adhesive layer.

[0038] <Electrode body for non-aqueous electrolyte secondary battery> The electrode assembly of the present disclosure includes a positive electrode plate, a separator, and a negative electrode plate. The electrode assembly may be a wound type electrode assembly 50 shown in Fig. 5. The electrode assembly may be a laminated type electrode assembly 50 shown in Fig. 6. The above description applies to the positive electrode plate, the separator, and the negative electrode plate.

[0039] At least one of the positive electrode plate and the negative electrode plate is disposed in contact with the adhesive layer. The adhesion between the substrate and at least one of the positive electrode plate and the negative electrode plate disposed in contact with the adhesive layer may be, for example, 0.2 to 5.0 kN / m. When the adhesion is in the above range, the formability of the electrode body and the injectability and impregnation of the non-aqueous electrolyte tend to be compatible. The adhesion is measured according to the method for measuring the adhesion described in the Examples section below. The adhesion may be preferably 0.5 to 5.0 kN / m from the viewpoint of the formability of the electrode body and the injectability and impregnation of the non-aqueous electrolyte.

[0040] When the substrate includes a porous film, the difference in porosity (hereinafter also referred to as reduced porosity) between the portion of the substrate in the separator facing at least one of the positive electrode plate and the negative electrode plate (also referred to as the electrode plate facing portion) and the portion not facing the positive electrode plate and the negative electrode plate (also referred to as the electrode plate non-facing portion) can be, for example, 8.0% or less. The reduced porosity is determined according to the method described in the Examples section below. The porosity reduction rate is preferably 4.0% or less, more preferably 3.0% or less, from the viewpoint of the injection property and the liquid impregnation property of the non-aqueous electrolyte, and may be, for example, 1.5% or more.

[0041] <Nonaqueous electrolyte secondary battery> FIG. 7 is a schematic diagram showing an example of the configuration of a battery in this embodiment. The battery 100 can be used for any purpose. For example, the battery 100 may be used as a main power source or a power source for power assist in an electric vehicle or the like. A battery module or a battery pack may be formed by connecting a plurality of batteries 100. The battery 100 may have a rated capacity of, for example, 1 to 300 Ah.

[0042] The battery 100 includes an electrode assembly 50 and a non-aqueous electrolyte (not shown). As shown in FIG. 1, the battery 100 may further include an exterior body 90. The exterior body 90 houses the electrode assembly 50 and the non-aqueous electrolyte. The exterior body 90 is rectangular (flattened rectangular parallelepiped). The exterior body 90 may be made of, for example, an aluminum (Al) alloy. The electrode assembly 50 may be housed in the exterior body 90 with pressure applied in the thickness direction (the D-axis direction in FIG. 7).

[0043] The exterior body 90 may include, for example, a sealing plate 91 and an exterior can 92. The sealing plate 91 closes the opening of the exterior can 92. For example, the sealing plate 91 and the exterior can 92 may be joined by laser processing or the like. The exterior body 90 may have any shape. The exterior body 90 may be, for example, in a pouch shape. That is, the exterior body 90 may be a pouch made of an Al laminate film or the like.

[0044] The sealing plate 91 is provided with a positive electrode terminal 81 and a negative electrode terminal 82. The sealing plate 91 may further be provided with an injection port (not shown), a gas exhaust valve (not shown), and the like. A non-aqueous electrolyte can be injected into the exterior body 90 from the injection port. The injection port can be closed by, for example, a sealing plug. The positive electrode current collecting member 71 connects the positive electrode terminal 81 and the electrode body 50. The positive electrode current collecting member 71 may be, for example, an Al plate. The negative electrode current collecting member 72 connects the negative electrode terminal 82 and the electrode body 50. The negative electrode current collecting member 72 may be, for example, a copper (Cu) plate.

[0045] The non-aqueous electrolyte is typically a liquid in which an electrolyte salt (in other words, a supporting salt) is dissolved or dispersed in a non-aqueous solvent. As the non-aqueous solvent, various organic solvents such as carbonates, ethers, esters, nitriles, sulfones, and lactones that are used in general electrolytes of lithium ion secondary batteries can be used without any particular limitation. Among them, carbonates are preferable, and specific examples thereof include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (MFEC), difluoroethylene carbonate (DFEC), monofluoromethyl difluoromethyl carbonate (F-DMC), and trifluorodimethyl carbonate (TFDMC). Such non-aqueous solvents can be used alone or in appropriate combination of two or more.

[0046] As the electrolyte salt, for example, lithium salts such as LiPF6, LiBF4, and lithium bis(fluorosulfonyl)imide (LiFSI) can be used, and LiPF6 is preferred. The concentration of the electrolyte salt is not particularly limited, but is preferably 0.7 mol / L or more and 1.3 mol / L or less. The non-aqueous electrolyte may contain various additives such as film-forming agents such as oxalate complexes, gas generating agents such as biphenyl (BP) and cyclohexylbenzene (CHB), and thickeners, in addition to the above-mentioned components, as long as the effects of the present invention are not significantly impaired. EXAMPLES

[0047] The present invention will be described in more detail below with reference to examples. In the examples, "%" and "parts" are by mass % and parts by mass unless otherwise specified.

[0048] [Separator] A separator was prepared which had a heat-resistant layer on one side of a PE film and adhesive layers containing an adhesive resin (glass transition temperature 35° C. or higher) on both sides of the heat-resistant layer.

[0049] [Method of measuring adhesion] The electrode bodies prepared in the examples and comparative examples were cut into pieces measuring 2 cm x 7 cm. The adhesion between the substrate and the positive electrode plate was measured at a tensile speed of 50 mm / min using a method conforming to JIS K6854-1. When the adhesion is 0.2 kN / m or more, it is determined that the adhesion between the separator and the electrode plate is sufficiently secured and the formability of the electrode body is good.

[0050] [Method for evaluating adhesive layer area ratio] The electrode assembly produced in the examples and comparative examples was disassembled, and the separator was separated. After that, the separator was set on the stage of the microscope so that the surface for which the adhesive coverage rate was to be calculated was facing up, and it was observed at a magnification of 10 to 200 times. At this time, if there was an adhesive coating arrangement pattern, the magnification was adjusted so that at least one period could be observed. Only the adhesive-covered areas in the observation range were made identifiable by binarization processing, and the adhesive layer area ratio was calculated.

[0051] [Method for evaluating impregnation of non-aqueous electrolyte] The ends of the electrode bodies prepared in the examples and comparative examples were immersed in a non-aqueous electrolyte solution placed in a tray and removed after 6 hours. The electrode bodies for impregnation evaluation were then disassembled, and the height of the non-aqueous electrolyte solution permeated from the immersed end was measured, and the impregnation of the non-aqueous electrolyte solution was evaluated according to the following criteria. ◎: Non-aqueous electrolyte has permeated to a height of 9cm or more 〇: The height of the non-aqueous electrolyte penetration is 6cm or more but less than 9cm △: The height of the non-aqueous electrolyte penetration is 3 cm or more but less than 6 cm ×: The non-aqueous electrolyte penetrated to a depth of less than 3 cm

[0052] [Method for evaluating reduced porosity] The electrode bodies prepared in the examples and comparative examples were disassembled, and the separators were taken out. The true densities ρt of the substrate in the separator at the plate facing portion and the plate non-facing portion were determined by a gas replacement method. He gas was used. The porosity of the substrate at the plate facing portion and the plate non-facing portion was calculated by the formula: (1-ρ / ρt)×100 using the apparent density ρ calculated from the thickness, area, and weight of the separator. The porosity reduction rate was calculated by the formula: (1-porosity of the plate facing portion / porosity of the plate non-facing portion)×100. When the porosity reduction rate is 8.0% or less, it is judged that the pores are not crushed by pressing, and the non-aqueous electrolyte is poured and impregnated well.

[0053] <Example 1> The positive and negative plates were laminated with a separator between them to produce a laminate. The laminate was pressed at a press temperature of 25°C, a press pressure of 10 MPa, and a press time of 3 seconds to produce an electrode body. The obtained electrode body was evaluated for the adhesion between the electrode plate and the separator, the adhesive layer area ratio, the impregnation speed, and the reduced porosity. The results are shown in Table 1.

[0054] <Examples 2 to 8 and Comparative Examples 1 to 8> An electrode assembly was produced in the same manner as in Example 1, except that the pressing temperature, pressing pressure, and pressing time in Example 1 were set as shown in Table 1, and that the adhesive layer was formed on the separator so as to achieve the adhesive surface coverage rate shown in Table 1. The results are shown in Table 1.

[0055] [Table 1]

[0056] As shown in Table 1, in Examples 1 to 8 according to the present disclosure, sufficient adhesion and impregnation speed of the nonaqueous electrolyte were ensured, and an electrode body with a small reduced porosity was obtained. Therefore, it is understood that the present disclosure can provide an electrode body for a nonaqueous electrolyte secondary battery and a manufacturing method thereof that can achieve both the formability of the electrode body and the injectability and impregnation property of the electrolyte. [Explanation of symbols]

[0057] 10 positive electrode plate, 11 positive electrode current collector, 12 positive electrode active material layer, 20 negative electrode plate, 21 negative electrode current collector, 22 negative electrode active material layer, 30 separator, 40 laminate, 41 cylindrical wound body, 42 assembled laminate, 50 electrode body, 71 positive electrode current collector, 72 negative electrode current collector, 81 positive electrode terminal, 82 negative electrode terminal, 90 exterior body, 91 sealing plate, 92 exterior can, 100 battery.

Claims

1. A method for producing an electrode body for a non-aqueous electrolyte secondary battery, comprising: A preparation step of preparing a positive electrode plate, a negative electrode plate, a separator having a substrate and an adhesive layer containing an adhesive resin on at least one side of the substrate; a lamination step of placing the adhesive layer of the separator in contact with at least one of the positive electrode plate and the negative electrode plate to obtain a laminate including the positive electrode plate, the separator, and the negative electrode plate; a pressing step of pressing the laminate at a temperature equal to or lower than the glass transition point of the adhesive resin and at a pressure of 8 to 20 MPa to obtain an electrode body for a non-aqueous electrolyte secondary battery; Including, In a plan view of the separator, an area ratio of the adhesive layer to the base material is 10 to 70%.

2. The method for producing an electrode assembly for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the substrate comprises a porous film.

3. 2. The method for producing an electrode body for a non-aqueous electrolyte secondary battery according to claim 1, wherein the temperature at which the laminate is pressed in the pressing step is 15 to 35°C.

4. 2 . The method for producing an electrode body for a non-aqueous electrolyte secondary battery according to claim 1 , wherein in the pressing step, the laminate is pressed for a time period of 3 seconds or more and less than 30 seconds.

5. 2 . The method for producing an electrode body for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the separator further comprises a heat-resistant layer, and in the lamination step, the separator is disposed so that the heat-resistant layer side faces the positive electrode plate.

6. An electrode assembly for a non-aqueous electrolyte secondary battery comprising a positive electrode plate, a separator, and a negative electrode plate, The separator includes a substrate including a porous film and an adhesive layer including an adhesive resin on at least one side of the substrate, In a plan view of the separator, an area ratio of the adhesive layer to the base material is 10 to 70%; At least one of the positive electrode plate and the negative electrode plate is disposed in contact with the adhesive layer, the adhesion strength between the substrate and at least one of the positive electrode plate and the negative electrode plate arranged in contact with the adhesive layer is 0.2 to 5.0 kN / m; the porous film has a porosity in a portion facing both a positive electrode active material-coated portion and a negative electrode active material-coated portion, and a porosity in a portion not facing at least one of the positive electrode active material and the negative electrode active material, the difference being 8.0% or less.

7. 7. The electrode body for a non-aqueous electrolyte secondary battery according to claim 6, wherein the adhesive resin has a glass transition point of more than 35°C.

8. The separator further comprises a heat-resistant layer; 7. The electrode assembly for a non-aqueous electrolyte secondary battery according to claim 1, wherein the separator is disposed such that the heat-resistant layer side faces the positive electrode plate.

9. A non-aqueous electrolyte secondary battery comprising the electrode body for a non-aqueous electrolyte secondary battery according to claim 6.

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