WO2021166720A1

WO2021166720A1 - Non-aqueous electrolyte secondary battery and method for manufacturing same

Info

Publication number: WO2021166720A1
Application number: PCT/JP2021/004623
Authority: WO
Inventors: 智則前田
Original assignee: 三洋電機株式会社
Priority date: 2020-02-19
Filing date: 2021-02-08
Publication date: 2021-08-26
Also published as: JP2023037042A

Abstract

This non-aqueous electrolyte secondary battery comprises an electrode laminate made by laminating or winding a plurality of electrode laminate units in which a positive electrode plate and a negative electrode plate are laminated or wound with a separator interposed. The surface of the separator has an adhesive layer. In the plan view of the electrode laminate, the adhesive layer comprises a first region that has a relatively large adhesive strength, and exists discretely; and a second region that is other than the first region, and has a relatively small adhesive strength.

Description

Non-aqueous electrolyte secondary battery and its manufacturing method

This disclosure relates to a non-aqueous electrolyte secondary battery and a method for manufacturing the same.

In recent years, the demand for secondary batteries has been increasing in various situations. Among them, lithium ion secondary batteries as non-aqueous electrolyte secondary batteries using non-aqueous electrolytes are attracting attention because they can obtain high energy density. In this form of the secondary battery, a flat electrode body in which a positive electrode plate and a negative electrode plate are laminated in a plurality of layers via a separator is inserted into the exterior body. In the positive electrode plate, positive electrode mixture layers are provided on both sides of the positive electrode core body, and in the negative electrode plate, negative electrode mixture layers are provided on both sides of the negative electrode core body. The positive electrode active material and the negative electrode active material each have a structure capable of inserting and removing lithium ions. The separator is a porous substance that allows lithium ions to permeate, while preventing a short circuit due to electrical contact between the positive electrode plate and the negative electrode plate.

The positive electrode plate and the negative electrode plate are electrically connected to the current collector plate and inserted into the exterior body. The exterior body is sealed after injecting the electrolytic solution. In this secondary battery, an adhesive layer is provided on the surface of the separator so that direct contact between the positive and negative electrodes does not occur due to the shrinkage of the separator, and the positive electrode plate / separator and the negative electrode plate / separator are bonded by heat pressure bonding. I'm letting you.

Patent Document 1 describes a strip-shaped electrode before integration, with an object of suppressing the occurrence of a large warp over the entire electrode laminate composed of the first separator, the first electrode plate, the second separator, and the second electrode plate. It includes a pair of pressure rolls that continuously pressurize and integrate the laminated body in the thickness direction in the roll gap, and a warp regulating member 120 that regulates the movement of the strip-shaped electrode laminated body before integration in the thickness direction. An apparatus for manufacturing an electrode laminate is described.

JP-A-2019-125441

When the electrode and the separator are bonded to each other to manufacture an electrode laminate, it is necessary to bond the two with sufficient adhesive force. On the other hand, when the gap between the electrode and the separator disappears, the electrolyte permeation time increases. There is a problem that it ends up. Further, if the adhesive force between the electrode and the separator is excessive, the electrical characteristics may be deteriorated due to the decrease in the mobility of the electrolytic solution.

The non-aqueous electrolyte secondary battery according to the present disclosure includes an electrode laminate obtained by laminating or winding a plurality of electrode laminate units in which a first electrode plate and a second electrode plate are laminated or wound via a separator. The surface of the separator has an adhesive layer, and in a plan view of the electrode laminate, the adhesive layer is bonded to a first region in which the adhesive force is relatively large and discretely present, and a region other than the first region. It is a non-aqueous electrolyte secondary battery composed of a second region having a relatively small force.

In the present disclosure, when the electrolytic solution (non-aqueous electrolytic solution) is injected into the electrode laminate and permeated, the electrolytic solution permeates from the end portion to the central portion of the electrode laminate. If there is a second region where the adhesive force between the 1 electrode plate and between the separator and the second electrode plate is relatively smaller than that of the first region, the electrolytic solution easily permeates and the permeation rate is improved. Further, since the electrolytic solution easily permeates, the electrolytic solution easily permeates from the end portion to the central portion of the electrode laminate.

In one embodiment of the present disclosure, the first region and the second region are both linear and alternately arranged in a plan view of the electrode laminate.

Further, in another embodiment of the present disclosure, the first region is discretely arranged in a circular shape or an elliptical shape in a plan view of the electrode laminate.

Further, in still another embodiment of the present disclosure, the first region is arranged at an end or a corner in a plan view of the electrode laminate.

Further, in the method for manufacturing a non-aqueous electrolyte secondary battery according to the present disclosure, a plurality of electrode laminate units in which a first electrode and a second electrode are laminated or wound via a separator are laminated or wound to form an electrode laminate. Using the step of making and the hot plates arranged on one side and the other side of the electrode laminate in the stacking direction and having irregularities formed on the surface, the electrode laminate is partially formed from both sides in the stacking direction. This is a method for manufacturing a non-aqueous electrolyte secondary battery, which comprises a step of specifically applying pressure and heat, and a step of inserting the electrode laminate into a battery case and injecting a non-aqueous electrolyte solution.

In one embodiment of the present disclosure, the area ratio of the region where pressure is not applied in the step of partially applying pressure and heat is 10% or more in a plan view of the electrode laminate.

According to the present disclosure, it is possible to shorten the electrolytic solution permeation time while maintaining the adhesive force between the electrode and the separator, and it is possible to suppress the deterioration of the electrical characteristics due to the decrease in the electrolyte mobility.

FIG. 1 is a block diagram of a non-aqueous electrolyte secondary battery of the embodiment. FIG. 2 is an explanatory diagram of pressure application of the non-aqueous electrolyte secondary battery of the embodiment. FIG. 3 is an explanatory view between the electrode and the separator of the non-aqueous electrolyte secondary battery of the embodiment. FIG. 4 is an explanatory view of permeation of the electrolytic solution of the non-aqueous electrolyte secondary battery of the embodiment. FIG. 5 is an explanatory view of an unimpregnated region of a conventional non-aqueous electrolyte secondary battery. FIG. 6 is an explanatory view of an unimpregnated region of the non-aqueous electrolyte secondary battery of the embodiment. FIG. 7 is a pressure application explanatory view (No. 1) of the non-aqueous electrolyte secondary battery of another embodiment. FIG. 8 is a pressure application explanatory view (No. 2) of the non-aqueous electrolyte secondary battery of another embodiment. FIG. 9 is a pressure application explanatory view (No. 3) of the non-aqueous electrolyte secondary battery of another embodiment. FIG. 10 is a pressure application explanatory view (No. 4) of the non-aqueous electrolyte secondary battery of another embodiment. FIG. 11 is a block diagram (No. 1) of the non-aqueous electrolyte secondary battery of another embodiment. FIG. 12 is a block diagram (No. 2) of the non-aqueous electrolyte secondary battery of another embodiment. FIG. 13 is a block diagram (No. 3) of the non-aqueous electrolyte secondary battery of another embodiment.

Hereinafter, embodiments according to the present disclosure will be described based on the drawings.

First, the outline of the square secondary battery will be explained. The square secondary battery (hereinafter, simply referred to as a secondary battery) according to the embodiment of the present disclosure is provided with an electrode body, an electrolyte, an exterior body containing the electrode body and the electrolyte, and positive electrode terminals and negative electrode terminals. It is provided with a sealing plate that closes the opening of the exterior body. The electrode body has a structure in which positive electrodes and negative electrodes are alternately laminated via a separator. The exterior body is, for example, a flat, substantially rectangular parallelepiped-shaped metal square container having one end opened in the height direction. The exterior body and the sealing plate are made of, for example, a metal material containing aluminum as a main component.

The electrolyte is preferably a non-aqueous electrolyte, and includes, for example, a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. As the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and a mixed solvent of two or more of these may be used. The non-aqueous solvent may contain a halogen substituent in which at least a part of hydrogen in these solvents is substituted with a halogen atom such as fluorine. As the electrolyte salt, for example, a lithium salt such as _{LiPF 6 is used.}

A positive electrode terminal and a negative electrode terminal are attached to the sealing plate. The sealing plate has an elongated rectangular shape, and a positive electrode terminal is arranged on one end side in the longitudinal direction and a negative electrode terminal is arranged on the other end side in the longitudinal direction of the sealing plate. The positive electrode terminal and the negative electrode terminal are external connection terminals that are electrically connected to other secondary batteries and loads, and are attached to the sealing plate via an insulating member.

The positive electrode includes a positive electrode tab that is electrically connected to the positive electrode terminal, and the negative electrode includes a negative electrode tab that is electrically connected to the negative electrode terminal. The positive electrode terminals are electrically connected to a group of positive electrode tabs in which a plurality of positive electrode tabs are laminated via a positive electrode current collector plate, and the negative electrode terminals are laminated with a plurality of negative electrode tabs via a negative electrode current collector plate. It is electrically connected to the negative electrode tab group. Further, the sealing plate is provided with a liquid injection unit for injecting a non-aqueous electrolytic solution and a gas discharge valve for opening and discharging gas when an abnormality occurs in the battery.

The electrode body is divided into, for example, a first electrode group and a second electrode group. These electrode groups have the same laminated structure and dimensions as each other, and are arranged in a laminated manner in the thickness direction of the electrode body. At the upper end of each electrode group, a positive electrode tab group composed of a plurality of positive electrode tabs and a negative electrode tab group composed of a plurality of negative electrode tabs are formed and connected to each current collector plate of the sealing plate. The outer peripheral surface of these electrode groups is covered with a separator, and an independent battery reaction occurs in these electrode groups.

The electrode body includes a plurality of positive electrodes and a plurality of negative electrodes. The electrode group constituting the electrode body includes, for example, one more negative electrode than the positive electrode, and the negative electrodes are arranged on both sides in the thickness direction of the electrode group. One separator is arranged between the positive electrode and the negative electrode. Each of the electrode groups includes an adhesive layer and is manufactured using a thermal pressure bonding process. More specifically, the electrode laminate unit formed by laminating a plurality of electrode laminate units in which the positive electrode and the negative electrode are laminated via a separator is pressed in the lamination direction using a pair of hot plates to heat the electrode laminate. It is produced by applying pressure to the adhesive layer so that at least a part of the adhesive layer exhibits adhesive strength.

The positive electrode includes, for example, a positive electrode tab protruding to one side, and the negative electrode includes a negative electrode tab protruding to one side. In other words, the positive electrode and the negative electrode are laminated so that the tabs face the same direction. Further, the positive electrode tab is located on one end side in the lateral direction of the electrode body, the negative electrode tab is located on the other end side in the lateral direction of the electrode body, a plurality of positive electrode tabs are arranged in the thickness direction of the electrode body, and a plurality of negative electrode tabs are electrodes. They are stacked so as to line up in the thickness direction of the body.

The positive electrode has a positive electrode core body and a positive electrode mixture layer provided on the surface of the positive electrode core body. For the positive electrode core, a foil of a metal stable in the potential range of the positive electrode such as aluminum or an aluminum alloy, a film in which the metal is arranged on the surface layer, or the like can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive material, and a binder, and is preferably provided on both sides of the positive electrode core body. For the positive electrode, for example, a positive electrode mixture slurry containing a positive electrode active material, a conductive material, a binder, and the like is applied onto the positive electrode core, the coating film is dried, and then compressed to form the positive electrode mixture layer into the positive electrode core. It can be produced by forming on both sides of.

The positive electrode has a structure in which a positive electrode mixture layer composed of a positive electrode mixture is arranged over the entire surface of the positive electrode core body excluding the positive electrode tab (hereinafter referred to as “base”). The thickness of the positive electrode core is, for example, 5 μm to 20 μm, preferably 8 μm to 15 μm. The base of the positive electrode core has a quadrangular shape when viewed from the front, and the positive electrode tab protrudes from one side of the quadrangle. Generally, a single metal foil is processed to obtain a positive electrode core in which a base and a positive electrode tab are integrally molded.

Lithium transition metal composite oxide is used as the positive electrode active material. Metallic elements contained in the lithium transition metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In and Sn. , Ta, W and the like. Above all, it is preferable to contain at least one of Ni, Co and Mn. Examples of suitable composite oxides include lithium transition metal composite oxides containing Ni, Co and Mn, and lithium transition metal composite oxides containing Ni, Co and Al.

Examples of the conductive material contained in the positive electrode mixture layer include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. .. Further, these resins may be used in combination with a cellulose derivative such as carboxymethyl cellulose (CMC) or a salt thereof, polyethylene oxide (PEO), or the like.

The negative electrode has a negative electrode core body and a negative electrode mixture layer provided on the surface of the negative electrode core body and composed of a negative electrode mixture. As the negative electrode core, a metal foil such as copper that is stable in the potential range of the negative electrode, a film in which the metal is arranged on the surface layer, or the like can be used. The negative electrode mixture layer contains a negative electrode active material and a binder, and is preferably provided on both sides of the negative electrode core body. For the negative electrode, for example, a negative electrode mixture slurry containing a negative electrode active material and a binder is applied to the surface of the negative electrode core body, the coating film is dried, and then compressed to form the negative electrode mixture layer on both sides of the negative electrode core body. It can be produced by forming in.

The negative electrode has a structure in which a negative electrode mixture layer is formed on the entire surface of the negative electrode core body except for the negative electrode tab. The thickness of the negative electrode core is, for example, 3 μm to 15 μm, preferably 5 μm to 10 μm. As in the case of the positive electrode, the base of the negative electrode core has a quadrangular shape in front view, and the negative electrode tab protrudes from one side of the quadrangle. Generally, a negative electrode core body in which a base portion and a negative electrode tab are integrally molded by processing one metal foil is obtained.

As the negative electrode active material, for example, a carbon-based active material that reversibly occludes and releases lithium ions is used. Suitable carbon-based active materials are natural graphite such as scaly graphite, massive graphite, earthy graphite, and graphite such as artificial graphite such as massive artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB). Further, as the negative electrode active material, a Si-based active material composed of at least one of Si and a Si-containing compound may be used, or a carbon-based active material and a Si-based active material may be used in combination.

As the binder contained in the negative electrode mixture layer, fluororesin, PAN, polyimide, acrylic resin, polyolefin or the like can be used as in the case of the positive electrode, but styrene-butadiene rubber (SBR) may be used. preferable. Further, the negative electrode mixture layer preferably further contains CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol (PVA) and the like. Above all, it is preferable to use SBR in combination with CMC or a salt thereof, PAA or a salt thereof.

The above is the outline of the square secondary battery, and next, the structure of the electrode group and the separator in the present embodiment will be further described.

FIG. 1 is a schematic cross-sectional view when the electrode group is cut in a plane substantially orthogonal to the height direction in the stacking direction.

As shown in FIG. 1, a separator 10, a negative electrode plate 12, a separator 10, and a positive electrode plate 14 are laminated, and a plurality of units composed of these electrode plates and separators are laminated to form an electrode laminated body 16.

The separator 10 has a base material and a heat-resistant layer provided on one side in the thickness direction of the base material, and further has an adhesive on at least one side, preferably both sides. The base material is composed of a porous sheet having ion permeability and insulating properties. The separator 10 is a porous base material containing at least one selected from, for example, polyolefin, polyvinylidene fluoride, polytetrafluoroethylene, polyimide, polyamide, polyamideimide, polyether sulfone, polyetherimide, and aramid as a main component. It may be composed of, and polyolefin is preferable, and polyethylene and polypropylene are particularly preferable. The heat-resistant layer is provided for the purpose of protecting the separator 10 when the positive electrode plate 14 and the negative electrode plate 12 are short-circuited to generate heat. The heat-resistant layer contains inorganic particles such as aluminum oxide, and is composed of, for example, a ceramic heat-resistant layer.

The adhesive is provided with a heat-resistant layer on the entire surface of one side surface of the separator 10 in the thickness direction by an existing method such as vapor deposition, and then the entire surface of one side surface of the separator 10 provided with the heat-resistant layer and the heat-resistant layer. It is formed by arranging a plurality of dot-shaped adhesives (dot-shaped portions) by printing or the like so that the area density is substantially constant over the entire other side surface of the separator 10.

Here, in the plurality of dot-shaped adhesives, the amount of each dot-shaped adhesive is substantially the same. Further, the number density of the dot-shaped adhesive is substantially constant over the entire area of one side surface and the entire area of the other side surface of the separator 10. The adhesive may be applied not only in dots but also on the entire surface of the separator. That is, the adhesive may be arranged so that the area density is substantially constant on at least one of the entire surface of one side surface and the entire surface of the other side surface of the separator, and the adhesive layer may be provided on at least one side surface of the separator. As the adhesive, known materials such as an acrylic resin adhesive, a urethane resin adhesive, an ethylene-vinyl acetate resin adhesive, an epoxy resin adhesive, or a fluororesin adhesive can be used.

The positive electrode plate 14 and the negative electrode plate 12 are alternately laminated via the separator 10 so that one side surface of the separator 10 on which the adhesive is arranged faces the positive electrode plate 14, and then the electrode laminate 16 is formed, and then the stacking direction. A part of the adhesive is melted by applying pressure and heat to the electrode laminate 16 from both sides in the lamination direction with the heat plates 18 arranged on one side and the other side. In this way, the separator 10 and the positive electrode plate 14 are adhered with an adhesive, and the separator 10 and the negative electrode plate 12 are adhered with an adhesive, so that the separator 10 is displaced with respect to the positive electrode plate 14 and the negative electrode plate 12. This prevents the power generation performance from deteriorating.

The positive electrode plate 14 has a positive electrode core body and a positive electrode mixture layer provided on the surface of the positive electrode core body. The positive electrode mixture layer contains a positive electrode active material, a conductive material, and a binder. For example, a positive electrode mixture slurry containing a positive electrode active material, a conductive material, a binder, and the like is applied onto a positive electrode core body to obtain a coating film. Is dried and then compressed to form a positive electrode mixture layer on the surface of the positive electrode core.

The negative electrode plate 12 has a negative electrode core body and a negative electrode mixture layer provided on the surface of the negative electrode core body and composed of a negative electrode mixture. As the negative electrode core, a metal foil such as copper that is stable in the potential range of the negative electrode, a film in which the metal is arranged on the surface layer, or the like can be used. The negative electrode mixture layer contains a negative electrode active material and a binder, and is preferably provided on both sides of the negative electrode core body. In the negative electrode plate 12, for example, a negative electrode mixture slurry containing a negative electrode active material, a binder, and the like is applied to the surface of the negative electrode core body, the coating film is dried, and then compressed to form the negative electrode mixture layer into the negative electrode core body. It is produced by forming on both sides of. The electrode laminate 16 is inserted into an outer can as a battery case, a non-aqueous electrolyte solution is injected into the outer can, and then the injection portion is sealed with a blind rivet to form a non-aqueous electrolyte secondary battery. Will be done.

Conventionally, the heating plates 18 arranged on one side and the other side of the electrode laminate 16 uniformly apply pressure and heat to the electrode laminate 16 from both sides in the laminate direction, thereby forming one of the adhesives. The part is melted and the separator 10 and the positive electrode plate 14 are adhered with an adhesive, and the separator 10 and the negative electrode plate 12 are adhered with an adhesive. In this case, the space between the separator 10 and the positive electrode plate 14 and The gap between the separator 10 and the negative electrode plate 12 disappears, and the permeation time of the non-aqueous electrolyte solution increases. Further, although sufficient adhesive force is required between the separator 10 and the positive electrode plate 14 and between the separator 10 and the negative electrode plate 12, if the adhesive force is excessive, the mobility of the non-aqueous electrolyte solution is lowered. The electrical characteristics of the secondary battery may deteriorate due to this.

Therefore, in the present embodiment, the surface of the hot plate 18, that is, the surface in contact with the electrode laminate 16 is not a flat surface but an uneven surface, and pressure and heat are applied to the electrode laminate 16 on the uneven surface to apply pressure and heat to the electrode. Pressure and heat are applied non-uniformly to the laminate 16. Since the pressure and the amount of heat applied to the convex portion of the hot plate 18 are relatively large, the adhesive force between the separator 10 and the electrode plates (positive electrode plate 14 and negative electrode plate 12) is relatively large. On the contrary, since the pressure and the amount of heat applied are relatively small in the recesses of the hot plate 18, the adhesive force between the separator 10 and the electrode plates (positive electrode plate 14 and negative electrode plate 12) is relatively small. Therefore, between the separator 10 of the electrode laminate 16 and the electrode plates (positive electrode plate 14 and negative electrode plate 12), there is a first region having a relatively large adhesive force, and other regions having a relatively large adhesive force. A small second region is created. The uneven surface of the hot plate 18 may be formed, for example, by forming a plurality of grooves having a predetermined depth linearly extending in a plan view of the electrode laminate 16 at predetermined intervals.

FIG. 2 shows a plan view of the electrode laminate 16 when pressure and heat are applied to the electrode laminate 16 from both sides in the lamination direction by a hot plate 18 having an uneven surface. A negative electrode tab 20 is formed on the negative electrode plate 12, and a positive electrode tab 22 is formed on the positive electrode plate 14. By forming a plurality of linear grooves on the surface of the hot plate 18 in parallel with each other at predetermined intervals, the electrode laminate 16 is linearly pressured with the first region 100 as shown in FIG. , Second regions 102 to which no pressure is applied are alternately formed. In the first region 100, pressure and heat are applied to melt the adhesive, and the separator 10 and the positive electrode plate 14 are adhered, and the separator 10 and the negative electrode plate 12 are adhered to each other. On the other hand, in the second region 102, since no pressure is applied, the separator 10 and the positive electrode plate 14 are not adhered, and the separator 10 and the negative electrode plate 12 are also not adhered. Therefore, the second region 102 has a relatively smaller adhesive force than the first region 100. Since the first region 100 and the second region 102 are formed by the irregularities on the surface of the hot plate 18 arranged at predetermined intervals, the first region 100 and the second region 102 are discrete in the plan view of the electrode laminate 16. Is formed in.

In this way, the first region 100 and the second region 102 are formed discretely in a plan view, and the adhesive force between the separator 10 and the negative electrode plate 12 and the separator 10 and the positive electrode plate 14 are non-uniform, and the water is not water. The electrolytic solution is injected to impregnate the electrode laminate 16.

FIG. 3 is a partially enlarged view of the boundary between the separator 10 and the negative electrode plate 12 (or the positive electrode plate 14) when impregnated with the non-aqueous electrolytic solution. A gap 50 exists between the separator 10 and the negative electrode plate 12, and residual air 52 exists in the gap 50. When impregnated with the non-aqueous electrolytic solution, the non-aqueous electrolytic solution permeates from the end portion of the electrode laminate 16 toward the central portion thereof, and the residual air 52 in the void 50 is replaced with the non-aqueous electrolytic solution. Assuming that the atmospheric pressure is P0 and the osmotic pressure is P, the pressure of the residual air is the atmospheric pressure P0. .. When the separator 10 and the negative electrode plate 12 are adhered, residual air stays in the void 50 and the permeation rate decreases, but the separator 10 and the negative electrode plate 12 are not adhered or adhered. When the force is relatively small, the residual air can move in the void 50 and escape to the outside of the electrode laminate 16, so that the non-aqueous electrolyte solution easily permeates into the void 50.

FIG. 4 schematically shows the state of permeation of the non-aqueous electrolyte solution in the present embodiment. In the first region 100, the adhesive force between the separator 10 and the electrode plates (negative electrode plate 12 and positive electrode plate 14) is relatively large, and the structure is such that residual air in the void 50 is difficult to escape, so that the permeation rate of the non-aqueous electrolytic solution is high. Relatively small. Further, the second region 102 has a structure in which the adhesive force between the separator 10 and the electrode plate is relatively small (including the case where the adhesive force is zero) and the residual air in the void 50 is easily released, so that the non-aqueous electrolytic solution can be used. The penetration rate is relatively high. By forming the second region 102 in which the non-aqueous electrolytic solution easily permeates into the electrode laminate 16 in this way, the impregnation characteristics of the non-aqueous electrolytic solution can be improved.

5 and 6 schematically show the electrode laminate 16 after being impregnated with the non-aqueous electrolytic solution. FIG. 5 shows a non-water-free case in which the surface of the hot plate 18 is flattened and pressure and heat are uniformly applied to the electrode laminate 16 to bond the separator 10 and the electrode plates (negative electrode plate 12 and positive electrode plate 14). The unimpregnated region 200 of the electrolytic solution is shown. Since the non-aqueous electrolyte solution permeates from the end portion of the electrode laminate 16 toward the center portion, an unimpregnated region 200 is generated in the center portion of the electrode laminate 16. On the other hand, FIG. 6 shows an unimpregnated region 200 of the electrode laminate 16 of the embodiment in which the first region 100 and the second region 102 are formed. Since the permeation rate of the non-aqueous electrolytic solution is relatively high in the second region 102 and the structure is such that it is more easily permeated from the end to the center, the unimpregnated region 200 is also relatively small.

The non-aqueous electrolyte is less likely to permeate into the central portion of the electrode laminate 16 than the end portion. However, in the present embodiment, it can be said that the permeability of the non-aqueous electrolyte is particularly improved in the central portion of the electrode laminate 16.

In Japanese Patent Application Laid-Open No. 2019-125441, the strip-shaped electrode laminate before integration is continuously pressurized in the thickness direction in the gap portion of the roll having a groove to be integrated, but the target is only the first. It is a laminate composed of a separator, a first electrode plate, a second separator, and a second electrode plate, and it is an object to suppress the occurrence of a large warp, and the entire electrode laminate 16 is impregnated with a non-aqueous electrolyte solution. It does not improve the characteristics.

Further, in the present embodiment, as shown in FIG. 2, a plurality of first regions 100 are linearly formed at predetermined intervals in a plan view of the electrode laminate 16, but the formation region or existence of the first region 100 is not necessarily present. The aspect is not limited to this.

For example, as shown in FIG. 7, a plurality of first regions 100 may be formed linearly and diagonally at predetermined intervals in a plan view of the electrode laminate 16. Such a first region 100 can be formed by forming a groove of the hot plate 18 at an angle. Further, as shown in FIG. 8, a plurality of first regions 100 may be formed so as to be scattered in a circular shape or an elliptical shape in a plan view of the electrode laminate 16. Such a first region 100 can be formed by discretely forming circular or elliptical convex portions of the hot plate 18. Further, as shown in FIG. 9, in the plan view of the electrode laminate 16, the first region 100 may be locally formed in the vicinity of two sides facing each other. Further, as shown in FIG. 10, the first region 100 may be locally formed in the vicinity of the four corners in the plan view of the electrode laminate 16.

Further, in the present embodiment, as shown in FIG. 11, a separator, a negative electrode plate, a separator, and a positive electrode plate are laminated, and a plurality of units composed of these electrode plates and separators are laminated to form a negative electrode tab 20 and a positive electrode tab 22. Although the above-mentioned battery structure 250 has been illustrated, the battery structure is not limited to this, and for example, as shown in FIG. 12, even a battery structure 300 in which a separator, a negative electrode plate, a separator, and a positive electrode plate are wound. Well, or instead of the negative electrode tab 20 and the positive electrode tab 22, the battery structure 400 has a negative electrode 21 formed on one end side and a positive electrode 23 formed on the other end side around which the separator, the negative electrode plate, the separator, and the positive electrode plate are wound. May be good. In short, it can be applied to an electrode laminate formed by combining a plurality of laminate units composed of a separator, a negative electrode plate, a separator, and a positive electrode plate.

In the present embodiment, by forming the second region 102 having a relatively small adhesive force (including the case where it is not adhered), the residual air 52 can be easily released and the non-aqueous electrolytic solution can be easily permeated. However, if the abundance ratio of the second region 102 is excessive, the overall adhesive strength between the separator 10 and the electrode plates (negative electrode plate 12 and positive electrode plate 14) decreases, and on the other hand, the abundance ratio of the second region 102 If the amount is too small, the effect of improving the permeation rate of the non-aqueous electrolyte solution will be diminished. Therefore, it is preferable to adjust the abundance ratio of the second region 102 in consideration of the balance between the two. As an example, in the plan view of the electrode laminate 16, the abundance area of the second region 102 is 10% or more and 50%. It is preferably as follows. The ratio of the existing area may change depending on the existing form of the first region 100. However, regardless of the existence form of the first region 100, the existing area of the second region 102 is required to be at least 10% or more from the viewpoint of shortening the non-aqueous electrolyte permeation time.

Hereinafter, examples will be described.

<Example>
<Preparation of positive electrode>
Positive electrode mixture layers were formed on both sides of an aluminum foil having a thickness of 13 μm. The thickness of the positive electrode mixture layer was 62 μm on one side after the compression treatment. The length of the positive electrode plate in the lateral direction was 76.5 mm. The width (length in the lateral direction) of the current collecting tab portion where the positive electrode core was exposed was 19.6 mm. The length of the positive electrode plate in the longitudinal direction was 138.9 mm. The positive electrode mixture layer contains lithium nickel cobalt manganese composite oxide as a positive electrode active material, acetylene black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder in a mass ratio of 97: 2: 1. I tried to include it in.

<Manufacturing of negative electrode>
Negative electrode mixture layers were formed on both sides of a copper foil having a thickness of 8 μm. The thickness of the negative electrode mixture layer was set to 76 μm on one side after the compression treatment. The length of the negative electrode plate in the lateral direction was 78.2 mm. The width (length in the lateral direction) of the current collecting tab portion where the negative electrode core was exposed was set to 18.2 mm. The length of the negative electrode plate in the longitudinal direction was 142.8 mm. The negative electrode mixture layer contained graphite as a negative electrode active material, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) as a binder in a mass ratio of 98: 1: 1.

<Separator>
As the separator, a ceramic heat-resistant layer was coated on one side of a polyethylene single-layer base material, and an adhesive layer made of an acrylic resin was applied on both sides of the separator. The thickness of the base material layer of the separator was 12 μm, the thickness of the heat-resistant layer was 4 μm, and the width was 80.7 mm. Here, the amounts of the single dot-shaped adhesives were made to be substantially the same. Further, the number density of the dot-shaped adhesives was set to be substantially constant on one side surface of the separator.

<Preparation of non-aqueous electrolyte>
A mixed solvent was prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) at a volume ratio (25 ° C., 1 atm) of 30:30:40. _{LiPF 6} was added to this mixed solvent so as to have a concentration of 1.15 mol / L to prepare a non-aqueous electrolyte solution.

<Preparation of electrode body>
The number of laminated positive electrode plates was 35, and the number of laminated negative electrode plates was 36. An electrode laminate was prepared by insulating the positive electrode and the negative electrode so that the current collecting tabs of the positive electrode and the negative electrode did not overlap each other and laminating the positive electrode and the negative electrode.

Then, as an example, linear irregularities were formed obliquely on the surface, and a pressure of 2 MPa was applied from both sides in the stacking direction of the electrode laminate using a hot plate set at 100 ° C. In the plan view of the electrode laminate 16, the area ratio of the first region to which pressure is applied and the second region to which pressure is not applied is
1st area: 2nd area = 67%: 33%
Met.

Further, as a comparative example, a pressure of 2 MPa was applied from both sides in the stacking direction of the electrode laminate using a hot plate having a flat surface and set to 100 ° C.

<Battery assembly>
The exposed portion of the positive electrode core body in which a plurality of sheets were laminated was electrically connected to the positive electrode terminal via the positive electrode current collector. Further, the exposed portion of the negative electrode core body in which a plurality of sheets are laminated is electrically connected to the negative electrode terminal via the negative electrode current collector. The positive electrode terminal and the negative electrode terminal were fixed to the sealing body via insulating members, respectively. The sealing body is provided with a gas discharge valve that opens when a predetermined pressure is applied. The positive electrode current collector, the positive electrode terminal, and the sealing body were made of aluminum or an aluminum alloy, respectively. The negative electrode current collector and the negative electrode terminal were made of copper or a copper alloy, respectively. The electrode body was joined to the sealing body in a state where the two electrode groups were overlapped with each other, and then inserted into an outer can as a battery case with one side open with an insulating sheet made of a resin material interposed therein. .. As the outer can, for example, one made of aluminum or an aluminum alloy was used. The sealing body was fitted into the opening of the outer can, and the fitting portion between the sealing body and the outer can was laser welded. The sealing body was made of aluminum or an aluminum alloy. By injecting a non-aqueous electrolyte solution into the outer can from the electrolyte solution injection port and then sealing the electrolyte solution injection port with a blind rivet, the external dimensions are 148 mm in width × 91 mm in height × 26. A 5 mm square non-aqueous electrolyte secondary battery was prepared.

<Test method>
The battery of the example and the battery of the comparative example produced as described above were produced, and then disassembled to confirm the non-aqueous electrolyte impregnated region in the plan view of the electrode laminate. In addition, the amount of excess non-aqueous electrolyte that did not permeate the electrode laminate and the internal impedance (AC-IR) as the electrical characteristics of the electrode laminate were measured.

Table 1 shows the results.

As shown in Table 1, the area of the unimpregnated region in the central portion of the comparative example was 18.0%, whereas in the example, it was remarkably reduced to 7.6%. Further, the excess liquid was 8.29 g in the comparative example, whereas it was 4.27 g in the example, which was significantly reduced. Further, the internal impedance (AC-IR) was 0.603 mΩ in the comparative example, whereas it was remarkably reduced to 0.585 mΩ in the example.

In this way, it was confirmed that in the examples, the unimpregnated area was improved by about 10% as compared with the comparative example, and the electrical characteristics were also improved accordingly.

In the comparative example, the time until the area of the non-impregnated region becomes a sufficiently small level (impregnation time) is about 10 hours, but in the example, it is about 6.5 hours, and it is confirmed that it can be shortened by about 3.5 hours. Was done.

10 Separator 12 Negative electrode plate 14 Positive electrode plate 16 Electrode laminate 18 Hot plate 20 Negative electrode tab 22 Positive electrode tab 100 First region 102 Second region

Claims

An electrode laminate obtained by laminating or winding a plurality of electrode laminate units in which a first electrode plate and a second electrode plate are laminated or wound via a separator is provided.
The surface of the separator has an adhesive layer and
In a plan view of the electrode laminate, the adhesive layer is composed of a first region in which the adhesive force is relatively large and discretely present, and a second region other than the first region in which the adhesive force is relatively small. ,
Non-aqueous electrolyte secondary battery.
In a plan view of the electrode laminate, the first region and the second region are both linear and alternately arranged.
The non-aqueous electrolyte secondary battery according to claim 1.
In the plan view of the electrode laminate, the first region is discretely arranged in a circular or elliptical shape.
The non-aqueous electrolyte secondary battery according to claim 1.
In a plan view of the electrode laminate, the first region is arranged at an end or a corner.
The non-aqueous electrolyte secondary battery according to claim 1.
A step of creating an electrode laminate by laminating or winding a plurality of electrode laminate units in which the first electrode and the second electrode are laminated or wound via a separator.
Using a hot plate arranged on one side and the other side of the electrode laminate in the stacking direction and having irregularities formed on the surface, pressure and heat are partially applied to the electrode laminate from both sides in the stacking direction. And the process of giving
The step of inserting the electrode laminate into the battery case and injecting the non-aqueous electrolytic solution,
A method for manufacturing a non-aqueous electrolyte secondary battery.
In the step of partially applying pressure and heat, the area ratio of the region where pressure is not applied is 10% or more in the plan view of the electrode laminate.
The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 5.