JP2011222388A - Laminated secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated secondary battery capable of improving life characteristics and reliability.SOLUTION: A lithium-ion secondary battery (laminated secondary battery) 100 comprises an electrode group 50 with cathodes 10 that contain cathode active material layers 12 and anodes 20 that contain anode active material layers 22 and are placed opposite to the cathodes 10, a metallic sheath container 60 that encapsulates the electrode group 50 together with a nonaqueous electrolyte, and a swellable resin that is placed within the sheath container 60 and has a swelling property against the nonaqueous electrolyte. This swellable resin is dispersed in the active material layers of the electrode group 50, and a pressurizing force is applied to the electrode group 50 in a lamination direction by the swellable resin (active material layer) that swells as a result of a nonaqueous electrolyte being injected into the sheath container 60. At this point, the electrode group 50 has a pressurizing force applied to its cathode active material layers 12 and anode active material layers 22 except for (at least part of) edges of the cathodes 10 and anodes 20.

Description

  The present invention relates to a stacked secondary battery.

  In recent years, along with the rapid miniaturization and multi-functionalization of consumer mobile phones, portable electronic devices, personal digital assistants, etc., the battery that is the power source is compact, lightweight, high energy density, and repeated charging and discharging over a long period of time. There is a strong demand for the development of rechargeable batteries. As a secondary battery that satisfies these requirements, a lithium ion secondary battery having a higher energy density than other secondary batteries is the most promising, and various studies have been conducted to develop a better lithium ion secondary battery. Has been promoted.

In recent years, lithium ion secondary batteries have been used for power storage in consideration of environmental problems such as global warming. Furthermore, as measures against carbon dioxide (CO ₂ ) reduction and energy problems, there is an increasing expectation for the spread of hybrid vehicles (HEV: Hybrid Electric Vehicle) and electric vehicles (EV: Electric Vehicle) with low fuel consumption and low exhaust gas. Development and commercialization of lithium ion secondary batteries targeting on-vehicle batteries are also underway.

  Such a lithium ion secondary battery is generally packaged in such a manner that a positive electrode on which a positive electrode active material layer is formed and a negative electrode on which a negative electrode active material layer is formed are arranged so as to face each other with a separator interposed therebetween. After being stored in the body (storage container), a non-aqueous electrolyte is injected. And charging / discharging is performed by moving a lithium ion between a positive electrode and a negative electrode. An example of such a lithium ion secondary battery is described in Patent Documents 1 and 2, for example.

Patent Registration No. 3482604 JP 2000-149960 A

  As described above, the demand for lithium ion secondary batteries is increasing not only for portable devices such as cellular phones but also for large-scale power sources such as electric vehicles. As the demand for lithium ion secondary batteries increases, a longer life such as a large capacity and 500 cycles or more has been demanded.

  However, in such a lithium ion secondary battery, an internal short circuit may occur due to separation or removal of the active material from the active material layer due to expansion or contraction of the active material layer during charging and discharging. Generation | occurrence | production that a battery life falls by generation | occurrence | production arises. As a result, there arises a problem that the life characteristics and reliability are lowered.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a highly reliable stacked secondary battery having excellent life characteristics.

  In order to achieve the above object, a stacked secondary battery according to one aspect of the present invention includes a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer and arranged to face the positive electrode, An outer container including a laminate in which positive and negative electrodes are alternately laminated, a storage container for storing the laminate, and a sealing body for sealing the storage container, and disposed in the outer container and swellable with respect to the electrolyte And a swellable resin. And the pressing force is applied to the laminated body in the laminating direction by the swellable resin swollen by injecting the electrolytic solution into the exterior container.

  In the multilayer secondary battery according to this one aspect, as described above, the electrolyte solution is injected into the exterior container by disposing the swellable resin having swelling property with respect to the electrolyte solution in the exterior container. Thus, the swellable resin can be swollen. And pressing force can be applied to the laminated body accommodated in the exterior container by the swelling resin swollen by the injection of the electrolytic solution. Thereby, since the said laminated body can be fixed in an exterior container, the position shift of a laminated body can be suppressed. Therefore, it is possible to suppress the occurrence of an internal short circuit due to the occurrence of misalignment in the stacked body during expansion and contraction of the active material layer accompanying charging / discharging of the battery. As a result, cycle characteristics can be improved.

  Further, in one aspect, since the pressing force can be applied to the laminated body by the swellable resin swollen when the electrolytic solution is injected into the outer container, the positive electrode and the negative electrode are brought into close contact with each other by the pressing force. Can be made. For this reason, the cycle characteristics can be improved also by this.

  Therefore, the multilayer secondary battery according to one aspect can improve the life characteristics and reliability by being configured as described above.

  In the multilayer secondary battery according to the above aspect, preferably, the positive electrode and the negative electrode each have an edge and are pushed into regions of the positive electrode active material layer and the negative electrode active material layer excluding at least a part of the edge. Pressure is applied. If comprised in this way, it can suppress that the problem that the positive electrode and a negative electrode electrically short-circuit resulting from the burr | flash protrusion etc. which generate | occur | produce in an electrode edge part arises. Thereby, since generation | occurrence | production of the internal short circuit at the time of battery assembly can be suppressed, a yield can be improved. In addition, by improving the yield, it is possible to easily reduce the product price when manufacturing a large-capacity stacked secondary battery. Moreover, if comprised in this way, it can suppress effectively that an internal short circuit arises in the edge part (edge part) of an electrode at the time of expansion / contraction of the active material layer accompanying charging / discharging of a battery. Thereby, cycle characteristics can be improved effectively. In addition, the reliability can be further improved.

  In the multilayer secondary battery according to the above aspect, the positive electrode and the negative electrode are preferably applied with a pressing force in a region excluding the edge of the positive electrode active material layer and the edge of the negative electrode active material layer, respectively. Here, when the positive electrode active material layer and the negative electrode active material layer are formed by coating, swelled portions (projections) may be formed at the coating start end and coating end. In this case, when a pressing force is applied to the swelled portion (projecting portion), an internal short circuit may occur. However, if configured as described above, it is possible to suppress the pressing force from being applied to such a swelled portion (protruding portion), thereby suppressing the occurrence of an internal short circuit at the swelling portion (projecting portion). Can do. Thereby, since generation | occurrence | production of a short circuit can be suppressed effectively, a yield can be improved more easily.

  In the multilayer secondary battery according to the aforementioned aspect, a swellable resin is preferably dispersed in at least one of the positive electrode active material layer and the negative electrode active material layer. If comprised in this way, the active material layer which disperse | distributed swelling resin can be swollen by injecting electrolyte solution in an exterior container. And the pressing force can be applied to the laminated body accommodated in the exterior container by the active material layer swollen by the injection of the electrolytic solution. Thereby, cycle characteristics can be easily improved.

  In the laminated secondary battery according to the above aspect, preferably, a plate-like member made of a swellable resin is disposed between at least one of the sealing body and the laminated body and between the storage container and the laminated body. Yes. If comprised in this way, by pouring electrolyte solution in an exterior container, the plate-shaped member which consists of swelling resin will be swollen, and a pressing force will be easily applied to the laminated body accommodated in the exterior container. be able to.

  In this case, the plate-like member is preferably formed in a size corresponding to a region of the active material layer excluding the edge of the positive electrode active material layer and the edge of the negative electrode active material layer. With this configuration, it is possible to easily apply a pressing force to the region excluding the edge of the positive electrode active material layer and the edge of the negative electrode active material layer, so that the occurrence of an internal short circuit can be effectively suppressed. it can. Thereby, the reliability and the yield can be improved while improving the cycle characteristics.

  The multilayer secondary battery according to the above aspect may further include a separator disposed between the positive electrode and the negative electrode, and the separator may be made of the swellable resin. If comprised in this way, by pouring electrolyte solution in an exterior container, a separator can be swollen and a pressing force can be easily applied to the laminated body accommodated in the exterior container. In addition, the separator is disposed other than between the positive electrode and the negative electrode, and the separator disposed other than between the positive electrode and the negative electrode is swollen so that a pressing force is applied to the laminate housed in the outer container. It may be configured.

  In this case, preferably, the multilayer body includes a plurality of positive electrodes, separators, and negative electrodes, and the multilayer body is configured by sequentially stacking the positive electrodes, the separators, and the negative electrodes, and at least one of the plurality of separators. The part has a thickness different from other separators. If comprised in this way, since it can be made easy to adjust the pressing force applied to a laminated body, desired pressing force can be applied to a laminated body.

  In the stacked secondary battery according to the above aspect, the positive electrode and the negative electrode in the stacked body are preferably pressed in the stacking direction by the sealing body and the storage container. If comprised in this way, pressing force can be applied to a laminated body (a positive electrode and a negative electrode) more easily.

  In the multilayer secondary battery according to the above aspect, the swellable resin is selected from nitrile butadiene rubber, styrene butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride, polyvinyl alcohol, polyethylene oxide, propylene oxide, polystyrene, and polymethyl methacrylate. It is preferable that at least one kind is included.

  In the laminated secondary battery according to the above aspect, a gap is formed between the sealing body and the laminated body or between the storage container and the laminated body before the electrolyte solution is injected. May be. In this case, the gap C is preferably set to 0 mm <C <5 mm.

  In the stacked secondary battery according to the above aspect, preferably, the region to which the pressing force is applied in the positive electrode and the negative electrode is 1 mm or more from the outer edge of the positive electrode active material layer, or 1 mm from the outer edge of the negative electrode active material layer. This is the inner region. If comprised in this way, generation | occurrence | production of an internal short circuit can be suppressed easily.

  In the stacked secondary battery according to the above aspect, preferably, the positive electrode active material layer has a smaller plane area than the negative electrode active material layer, and the positive electrode and the negative electrode have a region where the pressing force is applied. It is a region 1 mm or more inside from the outer edge of the material layer. If comprised in this way, generation | occurrence | production of an internal short circuit can be suppressed more easily.

  In the stacked secondary battery according to the above aspect, a pressing force is preferably applied to a region 5 mm or more inside from the outer edges of the positive electrode active material layer and the negative electrode active material layer. If comprised in this way, generation | occurrence | production of an internal short circuit can be suppressed more easily.

  In the laminated secondary battery according to the above aspect, each of the storage container and the sealing body can be made of a metal material.

  In the stacked secondary battery according to the above aspect, the positive electrode and the negative electrode are preferably arranged to face the sealing body, and the storage container includes a bottom surface portion facing the positive electrode and the negative electrode, At least one of the bottom portions of the storage container is formed with a convex portion that protrudes toward the positive electrode and the negative electrode. If comprised in this way, a pressing force can be easily applied to the area | region of a positive electrode active material layer and a negative electrode active material layer except at least one part of the edge part of a positive electrode and a negative electrode.

  In this case, preferably, the convex portion has a substantially planar pressing surface corresponding to the region of the active material layer excluding the edge of the positive electrode active material layer and the edge of the negative electrode active material layer. If comprised in this way, pressing force can be more easily applied to the area | region of the positive electrode active material layer and negative electrode active material layer except at least one part of the edge part of a positive electrode and a negative electrode. In addition, since it is possible to suppress the pressing force from being concentrated at one point by applying a pressing force to the laminate with a substantially flat pressing surface, due to the pressing force being concentrated at one point, Generation | occurrence | production of the problem that a crack is formed in an active material layer can be suppressed. Thereby, the fall of the cycle characteristic resulting from a crack being formed can be suppressed. In addition, for example, when the tip of the convex portion is steep, there is an inconvenience that an internal short circuit is likely to occur, while the inconvenience can be avoided by making the pressing surface substantially planar as described above. it can.

  In the configuration including the convex portion, preferably, the convex portion is integrally formed on at least one of the sealing body and the bottom surface portion of the storage container. If comprised in this way, a convex part can be easily formed in at least one of a sealing body and the bottom face part of a storage area. In addition, even when the convex portion is formed, it is possible to suppress an increase in the number of parts.

  In the stacked secondary battery according to the above aspect, at least one of the storage container and the sealing body is preferably coated with a polymer laminate on the inner surface of the battery. The coating with the polymer laminate material may be applied to both the battery inner side and the battery outer side.

  In the stacked secondary battery according to the above aspect, preferably, the storage container is formed in a square shape, the surface having the largest area is the bottom surface portion, and the positive electrode and the negative electrode face the bottom surface portion. Thus, it is stored in the exterior container. If comprised in this way, a high capacity | capacitance square secondary battery can be obtained easily. Moreover, if comprised in this way, the workability | operativity at the time of accommodating an electrode (a positive electrode and a negative electrode) in a storage container can be improved.

  As described above, according to the present invention, it is possible to easily obtain a highly reliable stacked secondary battery having excellent life characteristics.

1 is an exploded perspective view of a lithium ion secondary battery according to a first embodiment of the present invention. 1 is an exploded perspective view of a lithium ion secondary battery according to a first embodiment of the present invention. 1 is an overall perspective view of a lithium ion secondary battery according to a first embodiment of the present invention. 1 is a plan view of a lithium ion secondary battery according to a first embodiment of the present invention. It is the perspective view which showed the structure of the electrode group of the lithium ion secondary battery by 1st Embodiment of this invention. It is the perspective view which showed the structure of the positive electrode of the lithium ion secondary battery by 1st Embodiment of this invention. It is the top view which showed the structure of the positive electrode of the lithium ion secondary battery by 1st Embodiment of this invention. It is the perspective view which showed the structure of the negative electrode of the lithium ion secondary battery by 1st Embodiment of this invention. It is the top view which showed the structure of the negative electrode of the lithium ion secondary battery by 1st Embodiment of this invention. It is sectional drawing which showed the structure of the exterior can of the lithium ion secondary battery by 1st Embodiment of this invention. It is the top view which showed the structure of the exterior can of the lithium ion secondary battery by 1st Embodiment of this invention. It is the top view which looked at the sealing board of the lithium ion secondary battery by 1st Embodiment of this invention from the back surface side. It is sectional drawing (figure which showed the state before pouring of a non-aqueous electrolyte) which showed typically the lithium ion secondary battery by 1st Embodiment of this invention. It is sectional drawing (sectional drawing along the AA of FIG. 3) which showed typically the lithium ion secondary battery by 1st Embodiment of this invention. It is sectional drawing (sectional drawing along the BB line of FIG. 3) which showed typically the lithium ion secondary battery by 1st Embodiment of this invention. It is a disassembled perspective view of the lithium ion secondary battery by 2nd Embodiment of this invention. It is sectional drawing (figure corresponding to the cross section along the AA line of FIG. 3) which showed typically the lithium ion secondary battery by 2nd Embodiment of this invention. It is sectional drawing (the figure corresponding to the cross section along the BB line of FIG. 3) which showed typically the lithium ion secondary battery by 2nd Embodiment of this invention. It is a disassembled perspective view of the lithium ion secondary battery by 3rd Embodiment of this invention. It is the fragmentary sectional view (figure which showed the state before pouring of nonaqueous electrolyte) which simplified and showed the lithium ion secondary battery by Example 1. FIG. It is the fragmentary sectional view (figure which showed the state after pouring of a nonaqueous electrolyte) which simplified and showed the lithium ion secondary battery by Example 1. FIG. It is the fragmentary sectional view (figure which showed the state before pouring of nonaqueous electrolyte) which simplified and showed the lithium ion secondary battery by Example 2. FIG. It is the fragmentary sectional view (figure which showed the state after pouring of a nonaqueous electrolyte) which simplified and showed the lithium ion secondary battery by Example 2. FIG. It is the fragmentary sectional view (figure which showed the state before pouring of nonaqueous electrolyte) which simplified and showed the lithium ion secondary battery by Example 3. FIG. It is the fragmentary sectional view (figure which showed the state after pouring of a non-aqueous electrolyte) which simplified and showed the lithium ion secondary battery by Example 3. FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. In the following embodiments, a case where the present invention is applied to a stacked lithium ion secondary battery which is an example of a stacked secondary battery will be described.

(First embodiment)
1 and 2 are exploded perspective views of a lithium ion secondary battery according to a first embodiment of the present invention. FIG. 3 is an overall perspective view of the lithium ion secondary battery according to the first embodiment of the present invention. FIG. 4 is a plan view of the lithium ion secondary battery according to the first embodiment of the present invention. 5 to 15 are views for explaining the lithium ion secondary battery according to the first embodiment of the present invention. FIG. 4 shows a state in which the sealing plate 80 originally provided is removed so that the inside of the lithium ion secondary battery can be seen. First, with reference to FIGS. 1-15, the lithium ion secondary battery 100 by 1st Embodiment of this invention is demonstrated.

  As shown in FIGS. 1 to 4, the lithium ion secondary battery 100 according to the first embodiment has a rectangular flat shape (see FIG. 3), and includes a positive electrode 10 (see FIG. 1) and a negative electrode 20 (FIG. 1). Electrode group 50 (see FIG. 1 and FIG. 2), and a metal outer container 60 that encloses the electrode group 50 together with a non-aqueous electrolyte.

  As shown in FIGS. 1 and 5, the electrode group 50 further includes a separator 30 for suppressing a short circuit between the positive electrode 10 and the negative electrode 20. The positive electrode 10 and the negative electrode 20 are arranged so as to face each other with the separator 30 in between. The electrode group 50 includes a plurality of positive electrodes 10, negative electrodes 20, and separators 30. The positive electrode 10, the separator 30, and the negative electrode 20 are sequentially stacked to form a stacked structure (laminated body 50 a). . Note that the positive electrodes 10 and the negative electrodes 20 are alternately stacked one by one. The electrode group 50 is configured such that one positive electrode 10 is positioned between two adjacent negative electrodes 20. Further, a separator 30 is disposed on the outermost side of the electrode group 50.

  Specifically, the electrode group 50 includes, for example, 24 positive electrodes 10, 25 negative electrodes 20, and 50 separators 30. The positive electrodes 10 and the negative electrodes 20 are alternately sandwiched between the separators 30. Are stacked.

  The positive electrode 10 constituting the electrode group 50 has a configuration in which the positive electrode active material layer 12 is supported on both surfaces of the positive electrode current collector 11 as shown in FIGS. 6 and 7.

  The positive electrode current collector 11 has a function of collecting the positive electrode active material layer 12. The positive electrode current collector 11 is made of, for example, a metal foil such as aluminum, titanium, stainless steel, nickel, iron, or an alloy foil made of these alloys, and has a thickness of about 1 μm to about 500 μm (for example, about 20 μm). It has the thickness of. The positive electrode current collector 11 is preferably an aluminum foil or an aluminum alloy foil, and the thickness is preferably 20 μm or less.

  In addition to the above, the positive electrode current collector 11 may be, for example, an aluminum or copper surface treated with carbon, nickel, titanium, silver or the like for the purpose of improving conductivity and oxidation resistance. . For these, the surface can be oxidized. Further, a clad material of copper and aluminum, a clad material of stainless steel and aluminum, or a plating material combining these metals may be used. A current collector in which two or more metal foils are bonded together can also be used. Furthermore, the positive electrode current collector 11 has a film shape, a sheet shape, a net shape, a punched or expanded shape, a lath body, a porous body, a foamed body, a formed body of fiber groups, etc. in addition to the foil shape. There may be.

The positive electrode active material layer 12 includes a positive electrode active material that can occlude and release lithium ions. Examples of the positive electrode active material include an oxide containing lithium. Specific examples include LiCoO ₂ , LiFeO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , and compounds in which transition metals in these oxides are partially substituted with other metal elements. Among these, in a normal use, it is preferable to use a material that can utilize 80% or more of the amount of lithium held by the positive electrode for the battery reaction. As a result, the safety of the secondary battery against accidents such as overcharging can be enhanced. Examples of such a positive electrode active material include a compound having a spinel structure such as LiMn ₂ O ₄ and LiMPO ₄ (M is at least one element selected from Co, Ni, Mn, and Fe). Examples thereof include compounds having an olivine structure. Among these, a positive electrode active material containing at least one of Mn and Fe is preferable from the viewpoint of cost. Furthermore, from the viewpoint of safety and charging voltage, it is preferable to use LiFePO ₄ . In LiFePO ₄ , since all oxygen (O) is bonded to phosphorus (P) by a strong covalent bond, release of oxygen due to a temperature rise hardly occurs. Therefore, it is excellent in safety.

  In addition, the thickness of the positive electrode active material layer 12 is preferably about 20 μm to 2 mm, and more preferably about 50 μm to 1 mm.

  Further, the configuration of the positive electrode active material layer 12 is not particularly limited as long as it includes at least the positive electrode active material. For example, the positive electrode active material layer 12 may include other materials such as a conductive material, a thickener, and a binder in addition to the positive electrode active material.

  The conductive material is not particularly limited as long as it is an electron conductive material that does not adversely affect the battery performance of the positive electrode 10. For example, carbon black, acetylene black, ketjen black, graphite (natural graphite, artificial graphite), carbon fiber, etc. These carbonaceous materials and conductive metal oxides can be used. Among these, as the conductive material, carbon black and acetylene black are preferable from the viewpoints of electron conductivity and coatability.

  As the thickener, for example, polyethylene glycols, celluloses, polyacrylamides, poly N-vinyl amides, poly N-vinyl pyrrolidones and the like can be used. Among these, as the thickener, celluloses such as polyethylene glycols and carboxymethyl cellulose (CMC) are preferable, and CMC is particularly preferable.

  The binder serves to bind the active material particles and the conductive material particles, for example, a fluorine-based polymer such as polyvinylidene fluoride (PVdF), polyvinylpyridine, polytetrafluoroethylene, or a polyolefin such as polyethylene or polypropylene. A polymer, styrene butadiene rubber, or the like can be used.

  Examples of the solvent for dispersing the positive electrode active material, the conductive material, the binder, and the like include, for example, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, Organic solvents such as N-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran can be used.

  The positive electrode 10 described above is obtained by mixing a positive electrode active material, a conductive material, a thickener and a binder, and adding a suitable solvent to form a paste-like positive electrode mixture. It is formed by compressing to dry the electrode and increasing the electrode density as necessary.

  Further, as shown in FIG. 7, the positive electrode 10 has a rectangular shape in plan view, and includes four edge portions 14 (two edge portions 14a in the X direction and two edge portions in the Y direction). 14b). In the first embodiment, the positive electrode 10 has a width w1 in the Y direction of about 146 mm, for example, and a length g1 in the X direction of about 208 mm, for example. Further, in the application region (formation region) of the positive electrode active material layer 12, the width w11 in the Y direction is the same as the width w1 of the positive electrode 10, for example, about 146 mm, and the length g11 in the X direction is, for example, It is about 196 mm. For this reason, the positive electrode active material layer 12 formed in the coating region is formed in a rectangular shape when seen in a plan view, and has four edge portions 13 (two edge portions 13a along the X direction, in the Y direction). It has two edges 13b) along.

  The positive electrode 10 has a current collector exposed portion 11a at one end in the X direction where the positive electrode active material layer 12 is not formed and the surface of the positive electrode current collector 11 is exposed. A current collector lead 5 (see FIG. 4 and FIG. 13), which will be described later, is electrically connected to the current collector exposed portion 11a. The four edge portions 13 in the positive electrode active material layer 12 are the same as those in the positive electrode 10 except for one side (the edge portion 13b on the current collector exposed portion 11a side) of the two edge portions 13b along the Y direction. It coincides with the edge 14.

  As shown in FIGS. 8 and 9, the negative electrode 20 constituting the electrode group 50 has a configuration in which a negative electrode active material layer 22 is supported on both surfaces of a negative electrode current collector 21.

  The negative electrode current collector 21 has a function of collecting the negative electrode active material layer 22. The negative electrode current collector 21 is made of, for example, a metal foil such as copper, nickel, stainless steel, iron, or a nickel plating layer, or an alloy foil made of these alloys, and has a thickness of about 1 μm to about 100 μm (for example, about 16 μm) in thickness. The negative electrode current collector 21 is preferably a metal foil made of copper or stainless steel, and the thickness is preferably 4 μm or more and 20 μm or less.

  Moreover, the negative electrode current collector 21 has a film shape, a sheet shape, a net shape, a punched or expanded shape, a lath body, a porous body, a foamed body, a formed body of fiber groups, etc. in addition to the foil shape. There may be.

The negative electrode active material layer 22 includes a negative electrode active material that can occlude and release lithium ions. As the negative electrode active material, for example, a material containing lithium or a material capable of occluding and releasing lithium is used. Further, in order to constitute a high energy density battery, it is preferable that the potential for insertion / extraction of lithium is close to the deposition / dissolution potential of metallic lithium. Typical examples thereof include particulate natural graphite or artificial graphite (scale-like, lump-like, fibrous, whisker-like, spherical, pulverized particle-like, etc.). As the negative electrode active material, artificial graphite obtained by graphitizing mesocarbon microbeads, mesophase pitch powder, isotropic pitch powder, or the like may be used. Further, graphite particles having amorphous carbon attached to the surface can also be used. Furthermore, lithium transition metal oxides, lithium transition metal nitrides, transition metal oxides, silicon oxides, and the like can also be used. For example, when lithium titanate typified by Li ₄ Ti ₅ O ₁₂ is used as the lithium transition metal oxide, the deterioration of the negative electrode 20 is reduced, so that the life of the battery can be extended.

  The thickness of the negative electrode active material layer 22 is preferably about 20 μm to 2 mm, and more preferably about 50 μm to 1 mm.

  Further, the configuration of the negative electrode active material layer 22 is not particularly limited as long as it includes at least a negative electrode active material. For example, the negative electrode active material layer 22 may include other materials such as a conductive material, a thickener, and a binder in addition to the negative electrode active material. In addition, what can be used for the positive electrode active material layer 12 can be used for other materials, such as a electrically conductive material, a thickener, and a binder.

  The negative electrode 20 described above is obtained by mixing a negative electrode active material, a conductive material, a thickener and a binder, and adding a suitable solvent to form a paste-like negative electrode mixture. It is formed by compressing to dry the electrode and increasing the electrode density as necessary.

  Further, as shown in FIG. 9, the negative electrode 20 has a rectangular shape in plan view, and includes four edge portions 24 (two edge portions 24a in the X direction and two edge portions in the Y direction). 24b). Further, the negative electrode 20 is formed in a larger planar area than the positive electrode 10 (see FIGS. 7 and 8). In the first embodiment, the negative electrode 20 has a width w2 in the Y direction larger than the width w1 (see FIG. 7) of the positive electrode 10, for example, about 150 mm, and the length g2 in the X direction is The length of the positive electrode 10 is longer than the length g1 (see FIG. 7), for example, about 210 mm. In addition, in the application region (formation region) of the negative electrode active material layer 22, the width w21 in the Y direction is the same as the width w2 of the negative electrode 20, for example, about 150 mm, and the length g21 in the X direction is, for example, About 200 mm. For this reason, the negative electrode active material layer 22 formed in the coating region is formed in a rectangular shape in plan view, and has four edge portions 23 (two edge portions 23a along the X direction, in the Y direction). It has two edges 23b) along.

  In addition, the negative electrode 20 has a current collector exposed portion 21 a in which the surface of the negative electrode current collector 21 is exposed without forming the negative electrode active material layer 22 at one end in the Y direction, like the positive electrode 10. . A current collector lead 5 (see FIG. 4 and FIG. 13), which will be described later, is electrically connected to the current collector exposed portion 21a to extract an electric current to the outside. The four edge portions 23 in the negative electrode active material layer 22 are in the negative electrode 20 except for one side (the edge portion 23b on the current collector exposed portion 21a side) of the two edge portions 23b along the Y direction. It coincides with the edge 24.

  Here, in 1st Embodiment, the swelling resin which has swelling property with respect to nonaqueous electrolyte solution is disperse | distributed in the active material layer of an electrode. For this reason, the lithium ion secondary battery 100 of 1st Embodiment is comprised so that the active material layer in which swelling resin was disperse | swelled after injection | pouring of a non-aqueous electrolyte.

  The swellable resin may be dispersed in both the positive electrode active material layer 12 and the negative electrode active material layer 22, or may be dispersed in either the positive electrode active material layer 12 or the negative electrode active material layer 22. Also good. The swellable resin may be dispersed in a part of the active material layers of the plurality of active material layers.

  Swellable resins dispersed in the active material layer are nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVdF), polyvinyl alcohol (PVA), polyethylene oxide (PEO). , Propylene oxide, polystyrene, and at least one selected from polymethyl methacrylate are preferable.

  The separator 30 constituting the electrode group 50 is preferably a separator having sufficient strength and capable of holding a large amount of electrolyte. From such a viewpoint, polyethylene, polypropylene, having a thickness of 10 μm to 50 μm and a porosity of 30% to 70%, Alternatively, a microporous film or a nonwoven fabric containing an ethylene-propylene copolymer is preferable.

  In addition to the above, the separator 30 may be, for example, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, polyether (polyethylene oxide, polypropylene). Oxide), cellulose (carboxymethylcellulose, hydroxypropylcellulose), poly (meth) acrylic acid, microporous film made of a polymer such as poly (meth) acrylate, and the like can be used. Furthermore, a multilayer film obtained by superimposing these microporous films can also be used.

  The thickness of the separator 30 is preferably 5 μm to 100 μm, and more preferably 10 μm to 30 μm. Further, the porosity of the separator 30 is preferably 30% to 90%, and more preferably 40% to 80%. If the thickness of the separator 30 is smaller than 5 μm, the mechanical strength of the separator 30 is insufficient, causing an internal short circuit of the battery. On the other hand, when the thickness of the separator 30 is larger than 100 μm, the distance between the positive electrode and the negative electrode is increased, and the internal resistance of the battery is increased. On the other hand, when the porosity is lower than 30%, the content of the non-aqueous electrolyte decreases and the internal resistance of the battery increases. On the other hand, if the porosity is higher than 90%, the positive electrode 10 and the negative electrode 20 are brought into physical contact, causing an internal short circuit of the battery. Further, the separator 30 may be used by stacking a plurality of separators in consideration of mechanical strength, non-aqueous electrolyte content, battery internal resistance, ease of internal short circuit of the battery, etc., depending on the thickness and porosity. Is possible.

  The separator 30 has a shape larger than the application region (formation region) of the positive electrode active material layer 12 and the application region (formation region) of the negative electrode active material layer 22. Specifically, the separator 30 has, for example, a vertical length (a length corresponding to the X direction) of about 154 mm and a horizontal length (a length corresponding to the Y direction) of about 154 mm. It is formed in a 206 mm rectangular shape.

  As shown in FIGS. 1 and 5, the positive electrode 10 and the negative electrode 20 described above are arranged such that the current collector exposed portion 11 a of the positive electrode 10 and the current collector exposed portion 21 a of the negative electrode 20 are positioned on opposite sides. The separator 30 is laminated between the positive electrode and the negative electrode.

  The nonaqueous electrolytic solution sealed together with the electrode group 50 in the outer container 60 is not particularly limited, but examples of the solvent include ethylene carbonate (EC), propylene carbonate, butylene carbonate, diethyl carbonate (DEC), Esters such as dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, dioxolane, diethyl ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, dimethyl sulfoxide, sulfolane, Polar solvents such as methylsulfolane, acetonitrile, methyl formate, methyl acetate can be used. These solvents may be used alone, or two or more kinds may be mixed and used as a mixed solvent.

The nonaqueous electrolytic solution may contain an electrolyte supporting salt. Examples of the electrolyte supporting salt include LiClO ₄ , LiBF ₄ (lithium borofluoride), LiPF ₆ (lithium hexafluorophosphate), LiCF ₃ SO ₃ (lithium trifluoromethanesulfonate), LiF (lithium fluoride), LiCl. Examples thereof include lithium salts such as (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), LiAlCl ₄ (lithium tetrachloride aluminate) and the like. These may be used singly or in combination of two or more.

  The concentration of the electrolyte supporting salt is not particularly limited, but is preferably 0.5 mol / L to 2.5 mol / L, and more preferably 1.0 mol / L to 2.2 mol / L. When the concentration of the electrolyte support salt is less than 0.5 mol / L, the carrier concentration for carrying charges in the non-aqueous electrolyte is lowered, and the resistance of the non-aqueous electrolyte may be increased. Further, when the concentration of the electrolyte supporting salt is higher than 2.5 mol / L, the dissociation degree of the salt itself is lowered, and there is a possibility that the carrier concentration in the non-aqueous electrolyte does not increase.

  The exterior container 60 that encloses the electrode group 50 is a large flat rectangular container. As shown in FIGS. 1 to 3, an exterior can 70 that houses the electrode group 50 and the like, and a sealing plate that seals the exterior can 70. 80. In addition, the outer can 70 that houses the electrode group 50 is double-sealed and sealed with a sealing plate 80. The outer can 70 is an example of the “storage container” in the present invention, and the sealing plate 80 is an example of the “sealing body” in the present invention.

  The outer can 70 is formed, for example, by performing deep drawing or the like on a metal plate, and has a bottom surface portion 71 and a side wall portion 72. As shown in FIGS. 10 and 11, an opening 73 for inserting the electrode group 50 (see FIG. 13) is provided at one end of the outer can 70 (opposite the bottom surface portion 71). The outer can 70 is formed in a rectangular can, and the surface having the largest area is a bottom surface portion 71.

  The inner diameter of the outer can 70 is such that the electrode group 50 can be accommodated so that the electrode surface faces the bottom surface 71. Specifically, the outer can 70 has, for example, a length in the vertical direction (length L in the Y direction in FIG. 11) of about 164 mm, and a length in the horizontal direction (in the X direction in FIG. 11). The length W) is about 228 mm. As shown in FIG. 13, the depth D of the outer can 70 is, for example, about 20 mm.

  As shown in FIGS. 10 and 11, the outer can 70 has an electrode terminal 74 formed on a side wall 72 on one side in the Y direction. Further, a container folding portion 75 for performing double-tightening sealing is provided at the periphery of the opening 73 of the outer can 70.

  The sealing plate 80 is formed, for example, by pressing a metal plate. As shown in FIG. 12, the sealing plate 80 includes a substantially flat panel portion 81 that closes the opening 73 of the outer can 70, a chuck wall portion 82 that extends upward and continues to the outer peripheral end of the panel portion 81, and a chuck wall. And a folded portion 83 connected to the outer peripheral end of the portion 82. Further, as shown in FIGS. 1 and 12, a liquid injection hole 84 for injecting a non-aqueous electrolyte is formed on one side in the X direction. The liquid injection hole 84 is formed in a size of φ2 mm, for example.

  The outer can 70 and the sealing plate 80 can be formed using, for example, a metal plate such as iron, stainless steel, or aluminum, a steel plate obtained by applying nickel plating to iron, a steel plate obtained by applying aluminum plating, or the like. Since iron is an inexpensive material, it is preferable in terms of price, but in order to ensure long-term reliability, a metal plate made of stainless steel, aluminum, or the like, or a steel plate or aluminium plated with nickel is used. It is more preferable to use a polished steel plate or the like. In addition to the above, a polymer laminate material (laminate plate) obtained by laminating the surface of a metal plate with a polymer material can also be used. In this case, it is preferable that at least the surface on the inner side of the battery is coated. In addition, the thickness of a metal plate can be about 0.4 mm-about 1.2 mm (for example, about 1.0 mm), for example.

  As shown in FIGS. 4, 14, and 15, the electrode group 50 is configured such that the positive electrode 10 (see FIG. 1) and the negative electrode 20 (see FIG. 1) face the bottom surface 71 of the outer can 70. Thus, it is stored in the outer can 70. The accommodated electrode group 50 includes a current collector exposed portion 11a (see FIG. 7) of the positive electrode 10 and a current collector exposed portion 21a (see FIG. 9) of the negative electrode 20 through the current collector lead 5, respectively. The electrode terminal 74 of the can 70 is electrically connected. The current collector lead 5 may be made of the same material as the current collector, but may be made of a different material. Further, a collector electrode (current collector member) is connected to each of the positive electrode 10 and the negative electrode 20, and the electrode group 50 and the electrode terminal 74 are electrically connected via the collector electrode. Also good.

  14 and 15, the opening 73 of the outer can 70 is double-wrapped and sealed with the sealing plate 80. Specifically, the sealing plate 80 is attached to the outer can 70 by crimping the tip portion of the folded portion 83 of the sealing plate 80 so as to be wound around the container folding portion 75 of the outer can 70.

  Further, the panel portion 81 of the sealing plate 80 is located below the peripheral edge of the opening 73 of the outer can 70 by the chuck wall portion 82 (on the bottom surface 71 side) by a predetermined distance.

  In the first embodiment, as shown in FIG. 13, the sealing plate 80 and the electrode group 50 are not in contact with each other in the state before the nonaqueous electrolyte is injected, and the sealing plate 80 and the electrode group 50 are not in contact with each other. A gap 95 is formed between them. It is preferable that the gap C of the gap portion 95 is configured to be smaller than 5 mm. That is, in the lithium ion secondary battery 100 according to the first embodiment, it is preferable that the interval C is set to satisfy 0 mm <C <5 mm. In addition, the electrode group 50 is fixed in the outer container 60 in order to prevent the displacement of the electrode group 50 accommodated in the outer container 60 before the non-aqueous electrolyte is injected. preferable. At this time, the electrode group 50 may be fixed using a collecting electrode (current collecting member) connected to the electrode.

  The nonaqueous electrolytic solution is injected, for example, under reduced pressure from the liquid injection hole 84 after the opening 73 of the outer can 70 is sealed with the sealing plate 80. And after installing the metal ball | bowl 90 (refer FIG. 3) of the diameter substantially the same as the liquid injection hole 84 in the liquid injection hole 84, the liquid injection hole 84 is sealed by resistance welding, laser welding, etc.

  In the lithium ion secondary battery 100 according to the first embodiment, when the battery internal pressure rises during overcharge or in a high temperature state, a safety valve for opening the battery internal pressure (in order to avoid danger such as battery explosion) ( (Not shown) is provided. And the sealing board 80 is attached with the sealing intensity | strength in which the pressure resistance of a sealing part becomes more than the operating pressure of a safety valve so that the exterior container 60 may not open before this safety valve operates.

  Here, in the first embodiment, after the opening 73 of the outer can 70 is sealed with the sealing plate 80, the non-aqueous electrolyte is injected to swell the active material layer in which the swellable resin is dispersed. However, due to the swelling of the active material layer, as shown in FIGS. 14 and 15, a pressing force is applied to the electrode group 50 (the positive electrode 10 and the negative electrode 20). That is, in the first embodiment, after injecting the non-aqueous electrolyte, the outer can 70 and the sealing plate 80 apply a pressing force in the stacking direction (depth direction of the outer can 70; Z direction) to the electrode group 50. It is configured to be.

  As shown in FIG. 7 and FIG. 9, the region to which the pressing force is applied in the positive electrode 10 and the negative electrode 20 The region 15 or the region 25 inside the negative electrode active material layer 22 separated from the outer edge of the negative electrode active material layer 22 by a distance b (b1 to b4). The distance a from the outer edge of the positive electrode active material layer 12 in the positive electrode 10 and the distance b from the outer edge of the negative electrode active material layer 22 in the negative electrode 20 are each preferably 1 mm or more, and more preferably 5 mm or more. In the first embodiment, since the positive electrode 10 has a smaller plane area than the negative electrode 20, the area where the pressing force is applied to the positive electrode 10 and the negative electrode 20 is 5 mm or more from the outer edge of the positive electrode active material layer 12. It is preferable to be in the region 15 inside the positive electrode active material layer 12 separated by a distance a. If comprised in this way, also in the negative electrode 20, a pressing force is applied in the area | region 25 inside the negative electrode active material layer 22 separated from the outer edge of the negative electrode active material layer 22 by the distance b of 5 mm or more.

  In the first embodiment, as shown in FIGS. 14 and 15, the positive electrode active material layer 12 and the negative electrode active material excluding the edge (end) 14 of the positive electrode 10 and the edge (end) 24 of the negative electrode 20 are used. In order to apply a pressing force to the region of the material layer 22, a convex portion 85 is formed on the sealing plate 80.

  Specifically, in the lithium ion secondary battery 100 of the first embodiment, the sealing plate 80 is configured to face the electrodes (the positive electrode 10 and the negative electrode 20), and the panel portion 81 of the sealing plate 80 includes The convex portion 85 that protrudes (in the Z direction) toward the electrode group 50 (the positive electrode 10 and the negative electrode 20) is formed. The convex portion 85 is formed integrally with the sealing plate 80 by pressing or the like, and has a substantially flat pressing surface 85a. The electrode group 50 is pressed in the stacking direction (Z direction) by the pressing surface 85a of the convex portion 85, and the four edge portions 13 of the positive electrode active material layer 12 and the four edge portions 23 of the negative electrode active material layer 22 are excluded. A pressing force is applied in the region 15 of the positive electrode active material layer 12 and in the region 25 of the negative electrode active material layer 22. For this reason, in the first embodiment, as shown in FIGS. 14 and 15, the region P to which the pressing force is applied by the convex portion 85 corresponds to the formation region M of the negative electrode active material layer 22 and the positive electrode active material layer 12. It is located inside the formation region N.

  As shown in FIG. 13, the pressing surface 85 a of the convex portion 85 has a substantially rectangular shape when seen in a plan view, and has a plane area smaller than the plane area of the positive electrode active material layer 12 (see FIG. 7). Is formed. The length L11 in the X direction of the pressing surface 85a is smaller than the length g1 in the X direction of the positive electrode active material layer 12 (see FIG. 7), for example, about 194 mm. Further, the length L12 of the pressing surface 85a in the Y direction is smaller than the width w1 (see FIG. 7) of the positive electrode active material layer 12 in the Y direction, for example, about 144 mm.

  In the first embodiment, the convex portion 85 is separated from the outer edge of the positive electrode active material layer 12 by a distance a from the inner region 15 of the positive electrode active material layer 12 or the outer edge of the negative electrode active material layer 22 by a distance b. A pressing force is applied to almost the entire surface of the inner region 25 of the negative electrode active material layer 22. The area of the positive electrode 10 and the negative electrode 20 to which the pressing force is applied is preferably 10% or more and 99% or less, more preferably 20% or more and 98% or less of the plane area of the positive electrode active material layer 12. .

  Further, the dispersion amount (content) of the swellable resin dispersed in the active material layer is such that when the non-aqueous electrolyte is injected and the active material layer swells, the gap between the sealing plate 80 and the electrode group 50 is reduced. The gap 95 is filled and the electrode group 50 comes into contact with the sealing plate 80, and the swelling of the active material layer is further suppressed between the sealing plate 80 and the outer can 70, and the electrode group 50 (positive electrode 10, negative electrode 20) is laminated. The amount is set such that the pressing force in the direction is applied. Further, the pressing force applied to the electrode group 50 is the restraint rate by the sealing plate 80 and the outer can 70 (the thickness of the electrode group 50 when the active material layer is freely swollen (the total thickness of the positive electrode 10, the negative electrode 20, and the separator 30). ) And the swelling ratio of the active material layer (swelling resin) so that a desired pressing force can be obtained. Content (dispersion amount)) and the gap C of the gap portion 95 are adjusted. The swelling ratio (dispersion amount) of the active material layer and the gap C of the gap portion 95 are adjusted so that the constraint ratio of the electrode group 50 is about 3% to 30% (for example, about 10%). Is preferred.

  In the lithium ion secondary battery 100 according to the first embodiment, as described above, the swelling resin is dispersed in at least one of the positive electrode active material layer 12 and the negative electrode active material layer 22, thereby providing non-water in the outer container 60. When the electrolytic solution is injected, the active material layer in which the swellable resin is dispersed can be swollen. And the pressing force of the lamination direction can be applied to the electrode group 50 (the positive electrode 10 and the negative electrode 20) accommodated in the exterior container 60 by the active material layer swollen by the injection of the non-aqueous electrolyte. Thereby, since the electrode group 50 (the positive electrode 10, the negative electrode 20) can be fixed in the exterior container 60, the position shift of the electrode group 50 (the positive electrode 10, the negative electrode 20) can be suppressed. As a result, it is possible to suppress the occurrence of an internal short circuit due to the displacement of the electrode group 50 (the positive electrode 10 and the negative electrode 20) during expansion and contraction of the active material layer accompanying charging / discharging of the battery.

  In the first embodiment, the positive electrode active material layer 12 and the negative electrode active material excluding the edge (end) 14 of the positive electrode 10 and the edge 24 of the negative electrode 20 when pressing force is applied to the positive electrode 10 and the negative electrode 20. By being configured to press against the region of the layer 22, it is possible to suppress the pressing force from being applied to the edge 14 of the positive electrode 10 and the edge 24 of the negative electrode 20.

  Here, each of the positive electrode 10 and the negative electrode 20 uses a long strip-shaped current collector sheet, and the positive electrode active material layer 12 or the negative electrode active material layer 22 is applied to the current collector sheet by a predetermined method. It is produced by cutting into individual electrode lengths. For the application of the active material layer to the current collector sheet, for example, the current collector exposed portions 11a and 21a that do not apply the active material layer are provided after applying the length necessary for forming one electrode. Further, a so-called intermittent application method (hereinafter referred to as “intermittent application method”) in which an operation of applying an active material layer for the next electrode is repeated is used. Further, as another coating method, for example, a coating method (hereinafter referred to as “continuous coating method”) in which the current collector exposed portions 11a and 21a are positioned at one end on the side orthogonal to the longitudinal direction and are continuously coated. Sometimes used.

  When the continuous coating method as described above is employed, when the long current collector sheet is cut, the active material layer and the current collector supporting the active material layer are simultaneously cut. Therefore, burr protrusions are generated on the cut surface of the current collector, and the cut surface of the active material layer and the vicinity of the cut surface are unstable due to the impact during cutting. Part of the material layer is likely to slide down.

  On the other hand, when the intermittent application method is adopted, the current collector exposed portions 11a and 21a are cut, so that the problem of sliding off of the active material layer hardly occurs. However, in the case of the intermittent application method, depending on the viscosity of the mixture paste and the like, raised portions may be formed at the application start end and application end of the active material layer. That is, a protrusion may be formed at the end (edge) of the active material layer. Further, there may be a step in the boundary portion between the non-coated part (current collector exposed part) of the current collector and the active material layer.

  Therefore, in the first embodiment, as described above, the positive electrode 10 and the edge (end) 14 of the positive electrode 10 and the edge (end) 24 of the negative electrode 20 are configured so as not to be pressed. Even when burr protrusions are generated on the cut surfaces of the positive electrode 10 and the negative electrode 20 in the formation process (cutting process) of the negative electrode 20, it is possible to suppress the short circuit between the positive electrode 10 and the negative electrode 20 due to the burr protrusion. . In addition, even if the active material layer becomes unstable at the cutting surface and the vicinity of the cutting surface due to impact at the time of cutting, and a part of the active material layer is likely to slide down at the edge of the active material layer, Since it is possible to suppress the pressing force from being applied to the appropriate part, it is possible to suppress the sliding off of the active material. Thereby, generation | occurrence | production of the internal short circuit resulting from the slid down active material penetrating the separator 30 can be suppressed. As a result, the occurrence of an internal short circuit can be suppressed during battery assembly or the like, so that a large capacity lithium ion secondary battery 100 can be obtained with a high yield.

  Further, in the first embodiment, a pressing force can be applied to the electrode group 50 by the swellable resin swollen by injecting the non-aqueous electrolyte into the outer container 60, so that the pressing force causes the positive electrode. 10 and the negative electrode 20 can be brought into close contact via the separator 30. Thereby, life characteristics such as cycle characteristics can be improved. Further, by applying a pressing force to the positive electrode 10 and the negative electrode 20, it is possible to suppress the displacement of the electrode, and this can also improve the cycle characteristics. Therefore, by configuring as described above, life characteristics and reliability can be improved.

  In the first embodiment, the positive electrode active material layer 12 excluding the four edge portions 13 of the positive electrode active material layer 12 and the four edge portions 23 of the negative electrode active material layer 22 by the outer can 70 and the sealing plate 80, respectively. Even when protrusions are formed at the application start end and application end of the active material layer by applying a pressing force in the region 15 and the region 25 of the negative electrode active material layer 22, the pressing force is applied to such a protrusion. Can be suppressed. In addition, even when a step is generated at the boundary portion between the current collector exposed portion and the active material layer, it is possible to suppress the pressing force from being applied to the step portion. For this reason, it is possible to suppress the occurrence of the inconvenience that the separator 30 is damaged due to the pressing force being applied to the region where the protruding portion or the step is formed. Thereby, since the contact with the positive electrode active material layer 12 and the negative electrode active material layer 22 resulting from damage of the separator 30 can be suppressed, generation | occurrence | production of an internal short circuit can also be suppressed by this.

  Furthermore, in 1st Embodiment, since it can comprise so that pressing force may not be applied to the edge part 14 of the positive electrode 10, and the edge part 24 of the negative electrode 20 by comprising as mentioned above, charging / discharging of a battery is possible. During the expansion and contraction of the active material layer, it is possible to suppress the occurrence of an internal short circuit at the edge (end) of the electrode. Therefore, the cycle characteristics can be improved also by this. In addition, reliability can be improved.

  As described above, in the lithium ion secondary battery 100 according to the first embodiment, in addition to improving the life characteristics and reliability, it is possible to improve the yield. The secondary battery 100 can be provided at a low price.

  Moreover, in 1st Embodiment, by forming the convex part 85 which protrudes toward the positive electrode 10 and the negative electrode 20 in the sealing board 80 which seals the opening part 73 of the armored can 70, this convex part 85 makes it easy. A pressing force can be applied to the regions of the positive electrode active material layer 12 and the negative electrode active material layer 22 excluding the edge (end) 14 of the positive electrode 10 and the edge (end) 24 of the negative electrode 20.

  In the first embodiment, by forming the convex portion 85 integrally with the sealing plate 80, the convex portion 85 can be easily formed on the sealing plate 80. In addition, even when the convex portion 85 is formed on the sealing plate 80, an increase in the number of parts can be suppressed.

  Moreover, in 1st Embodiment, when applying the pressing force by the convex part 85 (pressing surface 85a) of the sealing board 80 by forming the said convex part 85 so that it may have a substantially planar pressing surface 85a, It is possible to suppress the pressing force from being concentrated on one point of the active material layer. For this reason, it can suppress that the problem that a crack generate | occur | produces in an active material layer resulting from pressing force being concentrated on one point arises. Thereby, the fall of the cycle characteristic resulting from a crack generating in an active material layer can be suppressed. When the tip of the convex portion is steep (for example, when the tip of the convex portion is sharp), an internal short circuit is likely to occur. On the other hand, as described above, the pressing surface 85a of the convex portion 85 is The occurrence of an internal short circuit can be suppressed by adopting a substantially planar shape.

  The lithium ion secondary battery 100 according to the first embodiment configured as described above can be suitably used as a stationary power storage battery that requires a long life. Moreover, it can use suitably also as storage batteries for vehicle-mounted use, such as a hybrid vehicle (HEV) and an electric vehicle (EV). In addition, the lithium ion secondary battery 100 according to the first embodiment is suitable for a storage battery having a single battery capacity of 10 Ah or more, and particularly suitable for a large capacity storage battery having a single battery capacity of 50 Ah or more.

(Second Embodiment)
FIG. 16 is an exploded perspective view of a lithium ion secondary battery according to a second embodiment of the present invention. 17 and 18 are cross-sectional views schematically showing a lithium ion secondary battery according to a second embodiment of the present invention. Next, a lithium ion secondary battery 200 according to a second embodiment of the present invention will be described with reference to FIGS. 6 to 9, 13 and 16 to 18. In addition, in each figure, the same code | symbol is attached | subjected to a corresponding component, and the overlapping description is abbreviate | omitted.

  In the lithium ion secondary battery 200 according to the second embodiment, as shown in FIG. 16, a plate-shaped or sheet-shaped resin member 210 is disposed between the electrode group 50 and the bottom surface portion 71 of the outer can 70. Yes. The resin member 210 is made of a resin material that swells with respect to the nonaqueous electrolytic solution. The resin member 210 is an example of the “plate member” in the present invention. The swellable resin constituting the resin member 210 is nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyvinylidene fluoride, as in the swellable resin shown in the first embodiment. It is preferable that at least one selected from (PVdF), polyvinyl alcohol (PVA), polyethylene oxide (PEO), propylene oxide, polystyrene, and polymethyl methacrylate is included.

  In the second embodiment, unlike the first embodiment, the swellable resin is not dispersed in the active material layer of the electrode. That is, in the second embodiment, the pressing force is not applied to the electrode group 50 due to the swelling of the active material layer, but as shown in FIGS. 17 and 18, the electrode group 50 and the bottom surface portion 71 of the outer can 70 are formed. By the swelling of the resin member 210 disposed therebetween, a pressing force in the stacking direction (depth direction of the outer can 70; Z direction) is applied to the electrode group 50.

  In the second embodiment, as shown in FIG. 13, the sealing plate 80 and the electrode group 50 are not in contact with each other in the state before the non-aqueous electrolyte is injected, and the sealing plate 80 and the electrode group 50 are not in contact with each other. A gap portion 95 is formed between them. In addition, it is preferable that the gap C of the gap portion 95 is set so as to satisfy 0 mm <C <5 mm, as in the first embodiment.

  Moreover, as shown in FIGS. 16-18, the panel part 81 of the sealing board 80 is formed with the convex part 85 similar to the said 1st Embodiment.

  In addition, the resin member 210 disposed between the electrode group 50 and the outer can 70 has a substantially rectangular shape in plan view, and is formed in a size smaller than the positive electrode active material layer 12. Yes. That is, the resin member 210 according to the second embodiment includes the inside of the region 15 inside the positive electrode active material layer 12 separated from the outer edge of the positive electrode active material layer 12 shown in FIG. 7 by a distance a and the negative electrode shown in FIG. The active material layer 22 is formed in a size that can be accommodated in a region 25 inside the negative electrode active material layer 22 that is separated from the outer edge of the active material layer 22 by a distance b. Specifically, the resin member 210 is formed in substantially the same shape as the pressing surface 85a (see FIG. 13) of the convex portion 85 formed on the sealing plate 80, for example.

  In the lithium ion secondary battery 200 of the second embodiment configured as described above, the electrode group 50 is pressed in the stacking direction (Z direction) via the resin member 210. The resin member 210 and the sealing plate The four convex portions 85 of the positive electrode active material layer 12 (see FIGS. 6 and 7) have four edges 13 (see FIGS. 6 and 7) and the negative electrode active material layer 22 (see FIGS. 8 and 9). In the region 15 (see FIGS. 6 and 7) of the positive electrode active material layer 12 and in the region 25 (see FIGS. 8 and 9) of the negative electrode active material layer 22 except for one edge 23 (see FIGS. 8 and 9). A pressing force is applied to the. Therefore, in the second embodiment, the region P where the pressing force is applied by the swelling of the resin member 210 is positioned inside the formation region M of the negative electrode active material layer 22 and the formation region N of the positive electrode active material layer 12. is doing.

  In the second embodiment, the thickness of the resin member 210 and the gap C between the gap portions 95 (see FIG. 13) so that the pressing force applied to the electrode group 50 (the positive electrode 10 and the negative electrode 20) becomes a desired pressing force. ) Has been adjusted. The thickness of the resin member 210 may be determined so that a desired pressing force is applied to the electrode group 50 (the positive electrode 10 and the negative electrode 20) in consideration of an increase in thickness due to swelling.

  Other configurations of the second embodiment are the same as those of the first embodiment.

  In the second embodiment, as described above, the non-aqueous electrolyte is injected into the outer container 60 by disposing the resin member 210 made of a swellable resin between the sealing plate 80 and the electrode group 50. Thus, the resin member 210 made of a swellable resin is swollen, and a pressing force can be easily applied to the electrode group 50 (the positive electrode 10 and the negative electrode 20) housed in the outer container 60.

  In the second embodiment, the resin member 210 is made of the negative electrode active material layer 22 in the region 15 of the positive electrode active material layer 12 excluding the edge portion 13 of the positive electrode active material layer 12 and in the region 15 of the negative electrode active material layer 22. By forming a size that fits within the region 25, it is possible to easily apply a pressing force to the region excluding the edge 13 of the positive electrode active material layer 12 and the edge 23 of the negative electrode active material layer 22. Generation | occurrence | production of a short circuit can be suppressed effectively. Thereby, the reliability and the yield can be improved while improving the cycle characteristics.

  In the second embodiment, a short circuit between the outer can 70 and the electrode group 50 can be suppressed by arranging the resin member 210 made of a resin material between the outer can 70 and the electrode group 50.

  The resin member 210 may be fixed in advance to the bottom surface 71 of the outer can 70. As described above, if the resin member 210 is fixed to the bottom surface portion 71 of the outer can 70 in advance, the displacement of the resin member 210 can be suppressed, and therefore, the positive electrode can be more easily passed through the resin member 210. A pressing force can be applied in the region 15 of the active material layer 12 (see FIG. 7) and in the region 25 of the negative electrode active material layer 22 (see FIG. 9).

  Other effects of the second embodiment are the same as those of the first embodiment.

(Third embodiment)
FIG. 19 is an exploded perspective view of a lithium ion secondary battery according to a third embodiment of the present invention. Next, with reference to FIG. 13 and FIG. 19, the lithium ion secondary battery 300 by 3rd Embodiment of this invention is demonstrated. Note that, in FIG. 19, corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  The lithium ion secondary battery 300 according to the third embodiment is configured by combining the first embodiment and the second embodiment. Specifically, as shown in FIG. 19, a plate-shaped or sheet-shaped resin member 210 is disposed between the electrode group 50 (laminated body 50 a) and the bottom surface portion 71 of the outer can 70. In addition, a swellable resin having a swellability with respect to the non-aqueous electrolyte is dispersed in the active material layer of the electrode. Therefore, in the third embodiment, the pressing force in the stacking direction (the depth direction of the outer can 70; the Z direction) is applied to the electrode group 50 by the swelling of the active material layer and the swelling of the resin member 210. Has been.

  In the third embodiment, the dispersion amount of the swellable resin dispersed in the active material layer so that the pressing force applied to the electrode group 50 (the positive electrode 10 and the negative electrode 20) becomes a desired pressing force, the resin member 210. And the gap C (see FIG. 13) of the gap 95 are adjusted.

  Other configurations of the third embodiment are the same as those of the first and second embodiments. The effects of the third embodiment are the same as those of the first and second embodiments.

(Fourth embodiment)
Unlike the first to third embodiments, the lithium ion secondary battery according to the fourth embodiment is configured such that a pressing force in the stacking direction is applied to the electrode group by swelling of the separator. That is, in this 4th Embodiment, the separator is comprised from swelling resin which has swelling property with respect to a non-aqueous electrolyte. In addition, as swelling resin, the swelling resin similar to 1st-3rd embodiment can be used.

  In addition, the separator may be configured such that a part of the separators has a swelling rate different from that of other separators by changing the configuration of the swellable resin. Moreover, you may give the function which applies pressing force to an electrode group to the separator by comprising the separator of some separators with a swelling resin. Furthermore, you may comprise so that the increase amount of the thickness by swelling may differ by making a part of separator of a some separator into the thickness different from another separator.

  Specifically, for example, the separator disposed on the outermost side of the electrode group may be configured to have a higher swelling ratio than other separators, or the thickness of the separator disposed on the outermost side of the electrode group. May be configured to be larger than other separators. Further, for example, a plurality of separators may be stacked on the outermost side of the electrode group.

  Other configurations of the fourth embodiment are the same as those of the first to third embodiments. In addition, you may combine the structure of 4th Embodiment with the structure of the said 1st-3rd embodiment.

  In the fourth embodiment, as described above, the separator is made of a swellable resin so that the separator made of the swellable resin swells and is easily accommodated in an outer container (positive electrode, negative electrode). A pressing force can be applied.

  As described above, the pressing force applied to the electrode group can be easily adjusted by changing the thickness, swelling rate, etc., for some separators.

  Other effects of the fourth embodiment are the same as those of the first to third embodiments.

  Examples of the present invention will be described below. In addition, this invention is not limited to the Example shown below.

  The lithium ion secondary batteries of Examples 1 to 3 and the lithium ion secondary battery according to Comparative Example 1 corresponding to the first to third embodiments, respectively, were produced. 20 and FIG. 21 are partial cross-sectional views showing a simplified lithium ion secondary battery according to Example 1. FIGS. 22 and 23 show a simplified lithium ion secondary battery according to Example 2. It is a fragmentary sectional view. 24 and 25 are partial cross-sectional views showing a simplified lithium ion secondary battery according to Example 3. FIG. 20, FIG. 22, and FIG. 24 show the state before the non-aqueous electrolyte is injected, and FIGS. 21, 23, and 25 show the state after the non-aqueous electrolyte is injected. Yes.

<Example 1>
In Example 1, as shown in FIG. 20 and FIG. 21, the active material layer of the electrode is swollen after the non-aqueous electrolyte is injected by dispersing the swellable resin in the active material layer of the electrode. By suppressing the swelling of the layer between the sealing plate 80 and the outer can 70, a pressing force is applied to the electrode group 50. That is, in Example 1, a swellable resin was additionally dispersed in the active material layer of the electrode shown below. In Example 1, the positive electrode active material layer region and the negative electrode excluding the four edges of the positive electrode active material layer and the four edges of the negative electrode active material layer by forming the convex portions 85 on the sealing plate 80. It was comprised so that pressing force might be applied to the area | region of an active material layer. Specifically, the pressing force is applied to a region inside the positive electrode active material layer that is separated from the outer edge of the positive electrode active material layer by a distance of 2 mm. Note that polyethylene oxide was used as the swellable resin dispersed in the active material layer. In addition, the swelling resin was dispersed in the negative electrode active material layer so that, when freely swollen, the increase in thickness of the electrode group 50 due to swelling was about 3 mm. Further, the gap C of the gap portion 95 between the electrode group 50 and the sealing plate 80 was set to about 2 mm.

<Example 2>
In Example 2, as shown in FIGS. 22 and 23, a resin member 210 made of a swellable resin is disposed between the electrode group 50 and the outer can 70, and the resin member 210 is pressed against the electrode group 50 by swelling. The pressure was applied. The resin member 210 was formed using nitrile butadiene rubber. Furthermore, the resin member 210 was formed in a size corresponding to a region inside the positive electrode active material layer that was separated from the outer edge of the positive electrode active material layer by a distance of 3 mm. The sealing plate 80 was provided with a convex portion 85 similar to that in Example 1. The thickness of the resin member 210 was set to about 1 mm, and the gap C of the gap portion 95 between the electrode group 50 and the sealing plate 80 was set to about 1.5 mm.

<Example 3>
In Example 3, as shown in FIGS. 24 and 25, the swellable resin is dispersed in the active material layer of the electrode, and the resin member 210 made of the swellable resin is disposed between the electrode group 50 and the outer can 70. did. The electrode group 50 is configured to be pressed by swelling of the active material layer and the resin member 210. In addition, as in Example 1, polyethylene oxide was used for the swellable resin dispersed in the active material layer. That is, in Example 3, the swellable resin was additionally dispersed in the active material layer of the electrode shown below. In addition, the resin member 210 was formed using nitrile butadiene rubber as in Example 2. Further, the sealing plate 80 was provided with a convex portion 85 similar to that in Example 1. The swellable resin was dispersed in the negative electrode active material layer so that the increase in thickness of the electrode group 50 due to swelling was about 2 mm. The thickness of the resin member 210 was about 0.5 mm, and the gap C of the gap portion 95 between the electrode group 50 and the sealing plate 80 was set to about 1.5 mm.

<Comparative example 1>
In Comparative Example 1, a lithium ion secondary battery was produced in the same manner except that no pressing force was applied to the electrode group by the sealing plate and the outer can.

<Common to Examples 1 to 3 and Comparative Example 1>
[Production of positive electrode]
First, 90 parts by weight of LiFePO _{4 as} an active material, 50 parts by weight of acetylene black as a conductive material, and 5 parts by weight of polyvinylidene fluoride as a binder were mixed, and N-methyl-2-pyrrolidone was appropriately added and dispersed. Thus, the positive electrode mixture slurry was prepared. Next, this positive electrode mixture slurry was uniformly applied to a foamed aluminum current collector (positive electrode current collector) having a thickness of 1 mm, dried, and then compressed by a roll press to a thickness of 500 μm. Finally, the positive electrodes (positive electrode plates) of Examples 1 to 3 and Comparative Example 1 were manufactured by cutting into a desired size. The area of the positive electrode active material layer applied was 146 mm long and 196 mm wide, and the positive electrode (positive electrode current collector) was 146 mm long and 208 mm wide.

[Production of negative electrode]
After 90 parts by weight of natural graphite (Chinese natural graphite) and 10 parts by weight of polyvinylidene fluoride were mixed, N-methyl-2-pyrrolidone was appropriately added and dispersed to prepare a negative electrode mixture slurry. Next, this negative electrode mixture slurry was uniformly applied to a foamed nickel current collector (negative electrode current collector) having a thickness of 1 mm, dried, and then compressed by a roll press to a thickness of 500 μm. Finally, the negative electrodes (negative electrode plates) of Examples 1 to 3 and Comparative Example 1 were prepared by cutting into a desired size. The size of the area where the active material layer of the negative electrode was applied was 150 mm long and 200 mm wide, and the size of the negative electrode (negative electrode current collector) was 150 mm long and 210 mm wide.

[Preparation of non-aqueous electrolyte]
A non-aqueous electrolyte was prepared by dissolving 1 mol / L of LiPF ₆ in a mixed solution (solvent) in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 30:70.

[Assembly of secondary battery]
By laminating the positive electrode plate and the negative electrode plate in the order of the positive electrode plate, the separator, the negative electrode plate, the separator,... So that the separator enters between the positive electrode plate and the negative electrode plate. Formed. At this time, 24 positive plates and 25 negative plates were used so that the negative plates were located outside the positive plates. Further, by using 50 separators, the separator was positioned on the outermost side of the electrode group (laminated body).

  As the separator, a microporous polyethylene film having a thickness of 20 μm was used. The size of the separator was 154 mm in length and 206 mm in width so as to be larger than the size on which the active material layers of the positive electrode plate and the negative electrode plate were applied.

  As the outer container, an outer can and a sealing plate were formed by processing a steel plate having a thickness of about 1.0 mm plated with nickel. The inner diameter of the outer can was 164 mm long, 228 mm wide, and 20 mm deep. And after accommodating an electrode group (laminated body) in this exterior can, the sealing board was mounted and the battery was sealed by double winding.

  Subsequently, a predetermined amount of non-aqueous electrolyte was injected under reduced pressure from a φ2 mm injection hole provided in advance on the sealing plate. After the injection, a metal ball having the same diameter as the injection hole was placed in the injection hole, and the injection hole was sealed by resistance welding. In this way, 30 batteries of Examples 1 to 3 and Comparative Example 1 were produced. In Examples 1 to 3, the swellable resin swells due to the injection of the non-aqueous electrolyte, and a pressing force is applied to the electrode group, whereas in Comparative Example 1, a pressing force is applied to the electrode group. Absent.

  The lithium secondary battery batteries according to Examples 1 to 3 and Comparative Example 1 manufactured as described above were inspected, and defective batteries and non-defective batteries were selected. When the voltage was 0 V at the time of battery manufacture (during battery assembly), it was considered that an internal short circuit had occurred, so such a battery was excluded as a defective battery. And the characteristic evaluation was performed with respect to the battery judged to be a good product.

  Specifically, the remaining battery excluding the defective battery is charged with a constant current and a constant voltage for 5 hours up to 3.5 V, and then discharged with a constant current up to 2 V, thereby obtaining a battery capacity (initial battery). Capacity). And using this battery, the cycle test was done on the said charging / discharging conditions in 45 degreeC temperature environment. Thereafter, the discharge capacity after 200 cycles was measured, and the ratio (capacity retention) obtained by dividing the battery capacity at that time by the initial discharge capacity (initial battery capacity) was evaluated.

  Furthermore, a vibration test was performed using the battery subjected to the cycle test, and the capacity retention after the vibration test was calculated. Specifically, the battery whose discharge capacity after 200 cycles was measured was recharged to obtain a fully charged state. And the battery made into the full charge state was attached to the vibration apparatus, and the vibration was added to one direction (longitudinal direction; X direction) for 8 hours on the conditions of frequency 10Hz-55Hz. Thereafter, the discharge capacity of the battery was measured, and the ratio divided by the charge capacity was calculated as the capacity retention rate (%).

  These results are shown in Table 1 below. In Table 1, the capacity retention after 200 cycles indicates the average value of the batteries subjected to the cycle test. Further, the capacity retention after the vibration test indicates an average value of the batteries subjected to the vibration test.

  As shown in Table 1 above, in Examples 1 to 3 in which pressing force was applied to the positive electrode (positive electrode active material layer) and the negative electrode (negative electrode active material layer) by swelling of the swellable resin, no pressing force was applied. Compared to Comparative Example 1, it was confirmed that the number of defective batteries generated was reduced. Specifically, in Example 1, the number of defective batteries was one, and in Examples 2 and 3, the number of defective batteries was zero, whereas in Comparative Example 1, the number of defective batteries was five. As a result, the number of occurrences was much higher than that in Examples.

  In Examples 1 to 3, when a pressing force is applied to the electrode group (positive electrode, negative electrode), the pressing force is applied to a region excluding the edge of the positive electrode active material layer and the edge of the negative electrode active material layer. This is considered to be because the occurrence of an internal short circuit due to the burr protrusion or the like was suppressed. In Comparative Example 1, since no pressing force is applied to the electrode group, no pressing force is applied to the edge of the positive electrode active material layer and the edge of the negative electrode active material layer, while the pressing force is applied to the electrode group. It is considered that the positional deviation of the electrode group (positive electrode, negative electrode) is likely to occur because no is added. Then, when the electrode is displaced during battery assembly, an internal short circuit due to the electrode displacement is likely to occur. As a result, it is considered that the number of defective batteries was increased as compared with Examples 1 to 3.

  In Examples 1 to 3, it was confirmed that the capacity retention after 200 cycles was improved as compared with Comparative Example 1. Specifically, in Example 1, the capacity retention after 200 cycles was 93%, in Example 2, the capacity retention after 200 cycles was 92%, and in Example 3, the capacity retention after 200 cycles was A high capacity retention rate of 91% and 90% or more was obtained. As described above, the reason why the high capacity retention ratios were obtained in Examples 1 to 3 was that the positive electrode active material layer and the negative electrode active material layer were subjected to a pressing force, whereby the positive electrode (positive electrode active material layer) and the negative electrode ( This is considered to be because the negative electrode active material layer) was in close contact with each other and the positional displacement of the electrodes was prevented. On the other hand, in Comparative Example 1, the capacity retention was 84%, which was very low. This may be because the positive electrode and the negative electrode are displaced during expansion and contraction of the active material layer due to charging / discharging of the battery, and an internal short circuit (micro short circuit) occurs at the edge (end) of the electrode. . That is, in Comparative Example 1, unlike the example, since no pressing force is applied to the electrode group (positive electrode, negative electrode), displacement of the positive electrode and the negative electrode is likely to occur, and thus capacity retention after 200 cycles is maintained. The rate is thought to have decreased.

  Furthermore, in Examples 1 to 3, it was confirmed that the capacity retention after the vibration test was improved as compared with Comparative Example 1. Specifically, in Example 1, the capacity retention after the vibration test is 98%, in Example 2, the capacity retention after the vibration test is 96%, and in Example 3, the capacity retention after the vibration test is A high capacity retention rate of 95% or more was obtained in all cases, and almost no capacity reduction was observed. On the other hand, in Comparative Example 1, the capacity retention after the vibration test was 86%, and the decrease in the capacity retention due to vibration was recognized remarkably. This is because in Examples 1 to 3, since the positive electrode and the negative electrode are fixed in the outer container by applying a pressing force to the electrode group, it is difficult for the electrode to be displaced due to vibration. It is thought that. On the other hand, in Comparative Example 1, since no pressing force is applied to the electrode group, the electrode is displaced with respect to the vibration, which is considered to decrease the capacity retention rate.

  As described above, it is possible to improve the life characteristics and reliability by applying a pressing force to the electrode group (positive electrode, negative electrode) by swelling the swellable resin by injecting the non-aqueous electrolyte. Was confirmed. In addition, when applying a pressing force, by applying a pressing force to the region excluding the edge of the positive electrode active material layer (positive electrode) and the edge of the negative electrode active material layer (negative electrode), an internal short circuit during battery assembly is suppressed. Thus, it was confirmed that the yield can be improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first to fourth embodiments, the example in which the present invention is applied to a lithium ion secondary battery (non-aqueous electrolyte secondary battery) which is an example of a stacked secondary battery has been described. However, the present invention may be applied to non-aqueous electrolyte secondary batteries other than lithium ion secondary batteries. Moreover, you may apply this invention to secondary batteries other than a nonaqueous electrolyte secondary battery. Furthermore, the present invention can also be applied to secondary batteries that will be developed in the future.

  In the first to fourth embodiments, the inner region of the positive electrode active material layer and the inner side of the negative electrode active material layer excluding the four edges of the positive electrode active material layer and the four edges of the negative electrode active material layer. Although an example in which the pressing force is applied to the region has been shown, the present invention is not limited to this, and the region in which the pressing force is applied to the electrode group is at least a part of the edge of the positive electrode or the edge of the negative electrode. What is necessary is just the area | region of the active material layer except at least one part. For example, a pressing force is applied to a region inside the positive electrode active material layer and a region inside the negative electrode active material layer, excluding the three edges of the positive electrode active material layer and the three edges of the negative electrode active material layer. May be. In this case, for example, a pressing force may be applied to one side (the edge on the collector exposed portion side) of the two edges along the Y direction in the positive electrode active material layer. Similarly, for example, a pressing force may be applied to one side (the edge on the current collector exposed portion side) of two edges along the Y direction in the negative electrode active material layer. Furthermore, for example, in the positive electrode and the negative electrode, a pressing force may be applied to a part of the edge, or a pressing force may be applied to at least one of the four edges.

  Moreover, in the said 1st-4th embodiment, although the example which formed the active material layer on both surfaces of the electrical power collector was shown, this invention is not limited to this, An active material layer is formed only on the single surface of an electrical power collector. May be. Moreover, you may comprise so that the electrode (positive electrode, negative electrode) which formed the active material layer only in the single side | surface of a collector may be included in a part of electrode group.

  Moreover, in the said 1st-4th embodiment, although the example which double-sealed and sealed the opening part of the exterior can with the sealing board was shown, this invention is not limited to this, The sealing method of an exterior can is double. A method other than the wrapping seal may be used. For example, the outer can may be sealed by welding the sealing plate to the outer can.

  Moreover, in the said 1st-4th embodiment, although the example comprised so that the negative electrode (negative electrode active material layer) might become larger than the positive electrode (positive electrode active material layer), this invention is not limited to this. The positive electrode (positive electrode active material layer) and the negative electrode (negative electrode active material layer) may be configured to have the same size, or the positive electrode (positive electrode active material layer) is more than the negative electrode (negative electrode active material layer). You may comprise so that may become large. In this case, the region where the pressing force is applied to the electrode (electrode group) is preferably a region separated by 1 mm or more from the outer edge of the smaller one of the positive electrode and the negative electrode. When the negative electrode is smaller than the positive electrode, the area to which the pressing force is applied can be 10% or more and 99% or less with respect to the application area of the negative electrode active material layer.

  Further, in the first to fourth embodiments, the example in which the positive electrode and the negative electrode are arranged so that the current collector exposed portion of the positive electrode and the current collector exposed portion of the negative electrode are located on the opposite sides is shown. The invention is not limited to this, and the positive electrode and the negative electrode may be arranged so that the current collector exposed portion of the positive electrode and the current collector exposed portion of the negative electrode are located on the same side.

  Moreover, in the said 1st-4th embodiment, although the example which formed the electrical power collector exposure part in the end of an electrical power collector was shown, this invention is not restricted to this, The said electrical power collector exposure part is, for example, It may be formed at both ends of the current collector.

  Moreover, in the said 1st-4th embodiment, although the example which formed the convex part in the sealing plate was shown, this invention is not restricted to this, The bottom surface of an exterior can is formed without forming a convex part in a sealing plate. A convex portion may be formed toward the portion. Moreover, you may make it form a convex part in both the sealing board and the bottom face part of an exterior can.

  In the first to fourth embodiments, the shape, size, protrusion amount, and the like of the protrusions can be changed as appropriate. Also, the size and shape of the outer container can be variously changed.

  In addition, the configurations of the first to fourth embodiments described above can be combined as appropriate.

  Moreover, in the said 1st-4th embodiment, although the example which formed the convex part integrally in the sealing board was shown, this invention is not restricted to this, The said convex part can also be formed separately. Also when forming a convex part in the bottom face part of an exterior can, a convex part can be formed separately as above. Moreover, a convex part can also be integrally formed in the bottom face part of an exterior can.

  Moreover, although the example which formed one convex part in the sealing board was shown in the said 1st-4th embodiment, this invention is not restricted to this, Even if it forms two or more convex parts in a sealing board Good. Also when forming a convex part in the bottom face part of an exterior can, two or more convex parts can be formed like the above.

  Moreover, in the said 2nd and 3rd embodiment, although the example which distribute | arranged the resin member which consists of swelling resin between the electrode group and the bottom face part of the armored can was shown, this invention is not restricted to this, The above The resin member can be disposed between the electrode group and the sealing plate, or can be disposed both between the electrode group and the bottom surface of the outer can and between the electrode group and the sealing plate.

  In the second and third embodiments, it is possible to adopt a configuration in which no convex portion is formed on the sealing plate.

  In the second and third embodiments, a plurality of resin members made of a swellable resin may be placed between the electrode group and the bottom surface of the outer can. Further, a plurality of resin members may be arranged in parallel and arranged between the electrode group and the bottom surface portion of the outer can. The same configuration can be applied when a resin member is disposed between the electrode group and the sealing plate.

DESCRIPTION OF SYMBOLS 10 Positive electrode 11 Positive electrode collector 11a Current collector exposed part 12 Positive electrode active material layer 13, 14 Edge 20 Negative electrode 21 Negative electrode current collector 21a Current collector exposed part 22 Negative electrode active material layer 23, 24 Edge 30 Separator 50 Electrode Group 50a Laminate 60 Exterior container 70 Exterior can (storage container)
71 Bottom face part 72 Side wall part 73 Opening part 74 Electrode terminal 75 Container return part 80 Sealing plate (sealing body)
81 Panel portion 82 Chuck wall portion 83 Folded portion 84 Injection hole 85 Convex portion 85a Press surface 90 Metal ball 95 Gap portion 100, 200, 300 Lithium ion secondary battery (stacked type secondary battery)
210 Resin member (plate member)

Claims (20)

A positive electrode including a positive electrode active material layer;
A negative electrode including a negative electrode active material layer and arranged to face the positive electrode;
A laminate in which the positive electrode and the negative electrode are alternately laminated;
An outer container including a storage container for storing the laminate, and a sealing body for sealing the storage container;
A swellable resin disposed in the outer container and having a swelling property with respect to the electrolyte solution;
The laminated secondary battery is characterized in that a pressing force is applied in the laminating direction by the swellable resin swollen by injecting an electrolyte into the exterior container.   The positive electrode and the negative electrode each have an edge, and a pressing force is applied to regions of the positive electrode active material layer and the negative electrode active material layer excluding at least a part of the edge. The stacked secondary battery according to claim 1.   3. The positive electrode and the negative electrode, respectively, wherein a pressing force is applied to a region excluding an edge of the positive electrode active material layer and an edge of the negative electrode active material layer, respectively. The laminated secondary battery as described.   The multilayer secondary battery according to claim 1, wherein the swellable resin is dispersed in at least one of the positive electrode active material layer and the negative electrode active material layer. .   The plate-like member made of the swellable resin is disposed between at least one of the sealing body and the laminated body and between the storage container and the laminated body. The laminated secondary battery according to any one of -4.   The plate-like member is formed in a size corresponding to a region of the active material layer excluding an edge portion of the positive electrode active material layer and an edge portion of the negative electrode active material layer. The laminated secondary battery as described. A separator disposed between the positive electrode and the negative electrode;
The stacked secondary battery according to claim 1, wherein the separator is made of the swellable resin. The laminate includes a plurality of the positive electrode, the separator, and the negative electrode,
The laminate is configured by sequentially laminating the positive electrode, the separator, and the negative electrode,
The multilayer secondary battery according to claim 7, wherein at least a part of the plurality of separators has a thickness different from that of other separators.   The laminate according to any one of claims 1 to 8, wherein the positive electrode and the negative electrode in the laminate are pressed in the stacking direction by the sealing body and the storage container. Type secondary battery.   The swellable resin includes at least one selected from nitrile butadiene rubber, styrene butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride, polyvinyl alcohol, polyethylene oxide, propylene oxide, polystyrene, and polymethyl methacrylate. The multilayer secondary battery according to any one of claims 1 to 9. Before the electrolyte is injected, a gap is formed between the sealing body and the laminated body or between the storage container and the laminated body,
11. The multilayer secondary battery according to claim 1, wherein the gap C is 0 mm <C <5 mm.   The region to which the pressing force is applied in the positive electrode and the negative electrode is a region that is 1 mm or more inside from the outer edge of the positive electrode active material layer, or a region that is 1 mm or more inside from the outer edge of the negative electrode active material layer. The multilayer secondary battery according to any one of claims 1 to 11. The positive electrode active material layer has a smaller planar area than the negative electrode active material layer,
13. The stacked type according to claim 1, wherein a region to which a pressing force is applied in the positive electrode and the negative electrode is a region that is 1 mm or more inside from an outer edge of the positive electrode active material layer. Secondary battery.   14. The stacked type two according to claim 1, wherein a pressing force is applied to a region 5 mm or more inside from an outer edge of each of the positive electrode active material layer and the negative electrode active material layer. Next battery.   The stacked secondary battery according to claim 1, wherein each of the storage container and the sealing body is made of a metal material. The positive electrode and the negative electrode are arranged so as to face the sealing body, and the storage container includes a bottom surface part facing the positive electrode and the negative electrode,
The convex part which protrudes toward the said positive electrode and the said negative electrode is formed in at least one of the said sealing body and the bottom face part of the said storage container, The any one of Claims 1-15 characterized by the above-mentioned. The laminated secondary battery as described.   The convex portion has a substantially planar pressing surface corresponding to a region of the active material layer excluding an edge of the positive electrode active material layer and an edge of the negative electrode active material layer. The laminated secondary battery according to 1.   18. The stacked secondary battery according to claim 16, wherein the convex portion is formed integrally with at least one of the sealing body and a bottom surface portion of the storage container.   19. The laminated mold according to claim 1, wherein at least one of the sealing body and the storage container has a battery inner surface coated with a polymer laminate material. Next battery. The storage container is formed in a square shape, and the surface with the largest area is the bottom surface part,
The multilayer secondary battery according to any one of claims 1 to 19, wherein the positive electrode and the negative electrode are accommodated in the exterior container so as to face the bottom surface portion.

Images