JP2011222128A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery capable of improving life characteristics and yield.SOLUTION: This lithium-ion secondary battery (secondary battery) 100 comprises an electrode group 40 with cathodes 10 that contain cathode active material layers 12 and anodes 20 that contain anode active material layers 22 and are placed in opposite to the cathodes 10 across separators 30, current collecting members 50 connected to the cathodes 10 and anodes 20, and a metal sheath container 60 encapsulating the electrode group 40 and the current collecting members 50 in addition to a nonaqueous electrolytic solution. The sheath container consists of an exterior can 70 and a sealing plate 80 that seals an opening of the exterior can 70. A pressurizing force is applied to the current collecting members 50 by the exterior can 70 and the sealing plate 80, and across these current collecting members 50, the electrode group 40 (cathodes 10 and anodes 20) is fixed within the sheath container 60 with no pressurizing force applied on the cathode active material layers 12 or anode active material layers 22.

Description

  The present invention relates to a 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 Document 1, for example.

Patent Registration No. 3482604

  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 long life such as a large capacity and 500 cycles or more has been demanded. In addition, demands for low prices are increasing, and high yields are required.

  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 and contraction of the active material layer during charging and discharging. This causes a disadvantage that the battery life is reduced. As a result, there arises a problem that the life characteristics and reliability are lowered.

  In addition, when an internal short circuit occurs during battery manufacture, there arises a problem that yield decreases. When attempting to increase the capacity of a lithium ion secondary battery, an extremely large amount of expensive positive electrode active material or electrolytic solution is used, resulting in a decrease in yield and an increase in product price. For this reason, the improvement of the manufacturing yield in a lithium ion secondary battery is very important.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a secondary battery capable of improving the yield.

  Another object of the present invention is to provide a reliable secondary battery having excellent life characteristics.

  In order to achieve the above object, a secondary battery according to one aspect of the present invention includes an electrode including an active material layer, a storage container that stores the electrode, and an exterior container that includes a sealing body that seals the storage container. ing. And the electrode is being fixed in the exterior container in the state in which the pressing force is not applied to the active material layer.

  In the secondary battery according to this one aspect, as described above, by preventing pressure from being applied to the active material layer of the electrode, even when the burr protrusion is generated on the electrode, the burr protrusion is generated. Since no pressing force is applied to the portion that is being performed, the occurrence of an internal short circuit due to a burr protrusion or the like can be suppressed. For this reason, generation | occurrence | production of the internal short circuit at the time of battery assembly can be suppressed. Thereby, 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 secondary battery.

  Moreover, in one situation, the positional displacement of the electrode can be suppressed by fixing the electrode in the outer container in a state where no pressing force is applied to the active material layer. Thereby, cycle characteristics can be improved. Therefore, by configuring as described above, life characteristics and reliability can be improved.

  Furthermore, in one aspect, by being configured as described above, it can be configured so that no pressing force is applied to the edge of the active material layer, so that when the active material layer expands and contracts due to charge / discharge of the battery , It is possible to suppress the occurrence of an internal short circuit (micro 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.

  The secondary battery according to the above aspect preferably further includes a current collecting member connected to the electrode, and the electrode is fixed in the outer container via the current collecting member. If comprised in this way, an electrode can be easily fixed in an exterior container in the state in which the pressing force is not applied to the active material layer.

  In this case, preferably, the pressing force is applied to the current collecting member by the storage container and the sealing body. If comprised in this way, since a current collection member can be fixed easily, the said electrode can be easily fixed in an exterior container via a current collection member.

  In the secondary battery according to the above aspect, the electrode preferably includes a positive electrode having a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, a negative electrode current collector, and the negative electrode current collector. Including a negative electrode active material layer formed on the body and a negative electrode disposed so as to face the positive electrode, and the positive electrode and the negative electrode are pressed against the positive electrode active material layer and the negative electrode active material layer, respectively. It is stored in the outer container in a state where it is not.

  In this case, preferably, a current collecting member connected to the electrode is provided, and the current collecting member is a first current collecting member connected to the positive electrode current collector and a second current collector connected to the negative electrode current collector. A pressing force is applied to each of the first current collecting member and the second current collecting member by the storage container and the sealing body. If comprised in this way, position shift of a positive electrode and a negative electrode can be suppressed effectively, suppressing that pressing force is added to an active material layer. Thereby, the cycle characteristics can be effectively improved and the occurrence of an internal short circuit can be effectively suppressed.

  In the configuration including the positive electrode and the negative electrode, each of the positive electrode current collector and the negative electrode current collector has a current collector exposed portion that is exposed without forming the positive electrode active material layer and the negative electrode active material layer. You may comprise so that pressing force may be applied to an electrical power collector exposure part with a container and a sealing body. Even in such a configuration, it is possible to effectively suppress the displacement of the positive electrode and the negative electrode while suppressing the pressing force from being applied to the active material layer.

  In the configuration including the positive electrode and the negative electrode, it is preferable that a separator is further provided between the positive electrode and the negative electrode, and the positive electrode, the separator, and the negative electrode are sequentially stacked to form a laminate. With this configuration, a highly reliable stacked secondary battery having excellent life characteristics can be obtained with a high yield.

  In this case, preferably, the laminate has a plurality of positive electrodes and negative electrodes, and the positive electrodes and the negative electrodes are alternately laminated. With this configuration, the capacity of the stacked secondary battery can be easily increased.

  In the configuration including the current collector connected to the positive electrode and the negative electrode, the positive electrode current collector and the negative electrode current collector are preferably exposed without forming the positive electrode active material layer and the negative electrode active material layer, respectively. The current collector exposed portion has a current collector exposed portion, and the current collector member includes a comb-like connection piece connected to the current collector exposed portion. If comprised in this way, since a current collection member can be easily connected to an electrode, the said electrode can be easily fixed in an exterior container via a current collection member. Thereby, an electrode can be more easily fixed in an exterior container in the state where pressing force is not applied to an active material layer. As a result, it is possible to more effectively suppress the displacement of the positive electrode and the negative electrode while suppressing the pressing force from being applied to the active material layer.

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

  The secondary battery according to the above aspect includes a current collecting member connected to the electrode, the electrode is disposed so as to face the sealing body, and the storage container includes a bottom surface portion facing the electrode. It is preferable that it is comprised. In this case, it is preferable that at least one of the sealing body and the bottom surface portion of the storage container is formed with a convex portion protruding toward the current collecting member. If comprised in this way, it can make it easy to press a current collection member with the said convex part. For this reason, since a current collection member can be easily fixed by pressing a current collection member with the said convex part, the said electrode can be easily fixed in an exterior container via a current collection member. it can.

  In the secondary battery according to the above aspect, preferably, at least one of the storage container and the sealing body is 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 secondary battery according to the above aspect, preferably, the storage container is formed in a square shape, the surface having the largest area is a bottom surface portion, and the electrode faces the bottom surface portion. It is arranged in the storage 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, a secondary battery capable of improving yield can be easily obtained.

  Further, according to the present invention, a highly reliable secondary battery having excellent life characteristics can be easily obtained.

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 electrode group of the lithium ion secondary battery by 1st Embodiment of this invention. It is sectional drawing of the current collection member of the lithium ion secondary battery by 1st Embodiment of this invention. It is sectional drawing (figure in the state where the current collection member was attached) which showed a part of electrode group of the lithium ion secondary battery by 1st Embodiment of this invention. It is the perspective view which showed typically the electrode group and current collection member of the lithium ion secondary battery by 1st Embodiment of this invention. It is a perspective view (figure which showed the state before attaching a sealing board) of the lithium ion secondary battery by a 1st embodiment of the present invention. 1 is a perspective view of an outer can of a lithium ion secondary battery according to a first embodiment of the present invention. It is a top view of the armored can of 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 the side view (figure showing the electrode group in the state where the current collection member was connected) showing typically the electrode group of the lithium ion secondary battery by a 1st embodiment of the present invention. It is the perspective view which showed typically the electrode group of the lithium ion secondary battery by the modification of 1st Embodiment (The figure which showed typically the electrode group of the state to which the current collection member was connected). It is a disassembled perspective view of the lithium ion secondary battery by 2nd Embodiment of this invention. It is sectional drawing of the current collection member of the lithium ion secondary battery by 2nd Embodiment of this invention. It is the side view (figure which showed typically the electrode group of the state where the current collection member was connected) which showed typically the electrode group of the lithium ion secondary battery by a 2nd embodiment of the present invention. It is sectional drawing which showed typically the lithium ion secondary battery by 2nd Embodiment of this invention. It is the side view (figure showing the electrode group in the state where the current collection member was connected) showing typically the electrode group of the lithium ion secondary battery by the modification of a 2nd embodiment. It is sectional drawing which showed typically the lithium ion secondary battery by the modification of 2nd Embodiment. It is sectional drawing of the current collection member of the lithium ion secondary battery by 3rd Embodiment of this invention. It is a disassembled perspective view of the current collection member of the lithium ion secondary battery by 3rd Embodiment of this invention. It is the disassembled perspective view which showed a part of electrode group of the lithium ion secondary battery by 3rd Embodiment of this invention. It is the perspective view which showed typically the electrode group of the lithium ion secondary battery by 3rd Embodiment of this invention (The figure which showed typically the electrode group of the state to which the current collection member was connected). It is the perspective view which showed typically the electrode group of the lithium ion secondary battery by the 1st modification of 3rd Embodiment (The figure which showed typically the electrode group in the state where the current collection member was connected). It is a top view of the current collection member of the lithium ion secondary battery by the 2nd modification of 3rd Embodiment. It is a side view of the B direction of FIG. It is the perspective view which showed typically the electrode group of the lithium ion secondary battery by 4th Embodiment of this invention (The figure which showed typically the electrode group in the state where the current collection member was connected). It is a top view (figure which showed a part of electrode group in the state where the current collection member was connected) of the electrode group of the lithium ion secondary battery by 4th Embodiment of this invention. It is the disassembled perspective view (figure which showed a part of electrode group in the state where the current collection member was connected) which showed a part of electrode group of the lithium ion secondary battery by 4th Embodiment of this invention. It is a top view of the electrode group of the lithium ion secondary battery by the modification of 4th Embodiment (The figure which showed a part of electrode group in the state where the current collection member was connected). FIG. 9 is an exploded perspective view of a lithium ion secondary battery according to a fifth embodiment of the present invention. It is a top view (figure which showed a part of electrode group in the state where the current collection tab was attached) of the electrode group of the lithium ion secondary battery by 5th Embodiment of this invention. 1 is a partial cross-sectional view schematically showing a lithium ion secondary battery according to Example 1. FIG. 6 is a partial cross-sectional view schematically showing a lithium ion secondary battery according to Example 2. FIG. 6 is a partial cross-sectional view schematically showing a lithium ion secondary battery according to Comparative Example 1. 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 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 18 are views for explaining a 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. 1-18, 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). (See FIG. 1 and FIG. 2), a current collecting member 50 connected to the positive electrode 10 and the negative electrode 20, and a metal that encloses the electrode group 40 and the current collecting member 50 together with a non-aqueous electrolyte. The outer container 60 is provided. The positive electrode 10 and the negative electrode 20 are examples of the “electrode” in the present invention.

  As shown in FIGS. 1 and 5, the electrode group 40 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 40 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 40 a). . Note that the positive electrodes 10 and the negative electrodes 20 are alternately stacked one by one. The electrode group 40 is configured such that one positive electrode 10 is located between two adjacent negative electrodes 20. Further, a separator 30 is disposed on the outermost side of the electrode group 40.

  Specifically, the electrode group 40 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.

  As shown in FIGS. 6 and 7, the positive electrode 10 constituting the electrode group 40 has a configuration in which the positive electrode active material layer 12 is supported on both surfaces of the positive electrode current collector 11.

  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 collecting member 50 (see FIGS. 4 and 13) for taking out an electric current to the outside 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 40 has a configuration in which the negative electrode active material layer 22 is supported on both surfaces of the 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, for example, about 210 mm (see FIG. 7). 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 collecting member 50 (see FIGS. 4 and 13) for taking out an electric current to the outside is electrically connected to the current collector exposed portion 21a. 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.

  The separator 30 constituting the electrode group 40 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.

  Further, as shown in FIG. 10, the separator 30 has a shape larger than the application region (formation region N) of the positive electrode active material layer 12 and the application region (formation region M) of the negative electrode active material layer 22. . Specifically, as shown in FIGS. 5 and 10, for example, the separator 30 has a vertical length (direction corresponding to the X direction) of about 154 mm and a horizontal length (Y direction). Is formed in a rectangular shape having a length in the direction corresponding to the length of about 206 mm.

  The positive electrode 10 and the negative electrode 20 described above are arranged such that the current collector exposed portion 11a of the positive electrode 10 and the current collector exposed portion 21a of the negative electrode 20 are located on opposite sides of each other, and a separator 30 is interposed between the positive and negative electrodes. Are stacked.

  As shown in FIG. 1, the current collecting member 50 includes a positive current collecting member 50 a connected to the positive electrode 10 and a negative current collecting member 50 b connected to the negative electrode 20. The current collecting members 50a and 50b are respectively a main body 51 extending along the current collector exposed portions 11a and 21a (extending in the Y direction) and a comb-like shape provided on one side surface 51a of the main body 51. Connection piece 52. 11, the height h1 of the current collecting member 50 (height h1 of the main body 51) is the thickness of the electrode group 40 (see FIGS. 2 and 14) in the stacking direction (the positive electrode 10 and the separator 30). And the total thickness of the negative electrode 20). Specifically, the height h1 of the current collecting member 50 is configured to be about 12 mm to about 17 mm, for example. The positive electrode current collecting member 50a is an example of the “first current collecting member” of the present invention, and the negative electrode current collecting member 50b is an example of the “second current collecting member” of the present invention.

  In the first embodiment, the current collecting member 50 is made of a metal material, and the connection piece 52 is formed integrally with the main body 51. The comb-shaped connection piece 52 can be formed, for example, by slitting a metal material with a dicing saw or the like. As shown in FIG. 12, when the current collecting member 50 is a positive current collecting member 50a, the thickness of the connecting piece 52 is configured to be substantially equal to the interval between the adjacent positive electrodes 10. preferable. Further, since the positive electrode 10 (current collector exposed portion 11 a) is inserted between the adjacent connection pieces 52, the interval between the adjacent connection pieces 52 is substantially equal to the thickness of the positive electrode current collector 11. It is preferable that it is comprised. Similarly, when the current collecting member 50 is a negative current collecting member 50b, the thickness of the connecting piece 52 is preferably configured to be substantially equal to the interval between the adjacent negative electrodes 20. Moreover, it is preferable that the interval between the adjacent connection pieces 52 is configured to be substantially equal to the thickness of the negative electrode current collector 21.

  As a metal material constituting the current collecting member 50, for example, iron, titanium, aluminum, copper, nickel, stainless steel, or an alloy thereof can be used. The positive electrode current collecting member 50a and the negative electrode current collecting member 50b may be made of the same material or different materials. The current collecting member 50 can be made of the same material as the current collector, but may be made of a different material.

  In the first embodiment, the current collector member 50a for the positive electrode has the connecting piece 52 electrically connected to the current collector exposed portion 11a of the positive electrode current collector 11, and the current collector member 50b for the negative electrode. The connecting piece 52 is electrically connected to the current collector exposed portion 21 a of the negative electrode current collector 21. Therefore, as shown in FIG. 14, the current collector member 50 a for the positive electrode is disposed on one side in the X direction with respect to the electrode group 40, and the current collector member 50 b for the negative electrode is disposed on the electrode group 40. It is arranged on the other side in the X direction. Further, the connecting pieces 52 of the current collecting members 50a and 50b are respectively connected to the current collector exposed portion 11a of the positive electrode current collector 11 and the current collector exposed portion 21a of the negative electrode current collector 21 by welding or ultrasonic bonding. Connection can be fixed. In addition, the connection fixation of the current collection member 50 and an electrode can also be performed using a conductive adhesive etc. other than welding and ultrasonic bonding, for example.

  The nonaqueous electrolytic solution sealed together with the electrode group 40 and the current collecting member 50 in the outer container 60 is not particularly limited, but examples of the solvent include ethylene carbonate (EC), propylene carbonate, butylene carbonate, diethyl Esters such as carbonate (DEC), dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, dioxolane, diethyl ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, Polar solvents such as dimethyl sulfoxide, sulfolane, methyl sulfolane, acetonitrile, methyl formate, and 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), L (1) Lithium salts such as Cl (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), LiAlCl ₄ (lithium tetrachloride aluminate) and the like can be mentioned. 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 40 is a large flat rectangular container. As shown in FIGS. 1 to 3, the exterior can 70 that houses the electrode group 40 and the current collecting member 50, and the exterior can 70. And a sealing plate 80 that seals. Further, the outer can 70 in which the electrode group 40 is accommodated is double-wrapped 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. 15 and 16, an opening 73 for inserting the electrode group 40 (see FIG. 14) 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 40 (see FIG. 14) to which the current collecting member 50 is connected can be accommodated so that the electrode surface faces the bottom surface 71. . Specifically, the outer can 70 has, for example, a longitudinal length (Y-direction length L in FIG. 16) of about 164 mm, and a lateral length (in the X-direction in FIG. 16). The length W) is about 228 mm. The depth of the outer can 70 is, for example, about 20 mm.

  Further, the outer can 70 has an electrode terminal 74 formed on a side wall portion 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. 2, 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 continues to the outer peripheral end of the panel portion 81 and extends upward, and a chuck wall And a folded portion 83 connected to the outer peripheral end of the portion 82. Further, as shown in FIGS. 2 and 3, 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.

  Also, as shown in FIGS. 4 and 14, the electrode group 40 described above is such that the positive electrode 10 (see FIG. 5) and the negative electrode 20 (see FIG. 5) face the bottom surface 71 of the outer can 70. It is stored in the outer can 70. Further, as shown in FIG. 14, the current collecting members 50 connected to the electrode group 40 are disposed at both ends in the X direction inside the outer can 70. Further, as shown in FIG. 4, the current collector 50a connected to the current collector exposed portion 11a (see FIG. 7) of the positive electrode 10 and the current collector exposed portion 21a (see FIG. 9) of the negative electrode 20 were connected. The current collecting members 50b are electrically connected to the electrode terminals 74 of the outer can 70 via the current collecting leads 5, respectively. Thereby, the positive electrode 10 and the negative electrode 20 are electrically connected with the electrode terminal 74 of the armored can 70 through the current collection member 50 and the current collection lead 5, respectively. The current collector lead 5 may be made of the same material as the current collector, but may be made of a different material.

  As shown in FIG. 17, 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. In FIG. 17, the description of the separator 30 is omitted.

  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. Accordingly, as shown in FIGS. 17 and 18, the main body 51 of the current collecting member 50 (50a, 50b) is stacked in the stacking direction by the outer can 70 (bottom surface 71) and the sealing plate 80 (panel 81). The pressing force is applied in the depth direction of the outer can 70 (Z direction). At this time, in order to prevent the outer container 60 and the current collecting member 50 from being electrically short-circuited, the outer container 60 and the current collecting member 50 are indirectly contacted via, for example, an insulating material. Yes. Specifically, for example, an insulating resin or the like is applied to a portion of the current collecting member 50 that contacts the outer container 60. In addition, for example, an insulating sheet (not shown) made of a resin material or the like may be interposed between the current collecting member 50 and the outer container 60 (the sealing plate 80 and the outer can 70). Furthermore, it is also preferable to coat a polymer laminate material or the like on the surface inside the battery of the outer container 60.

  Further, in the first embodiment, the current collecting members 50a and 50b are fixed in the outer container 60 by applying a pressing force to the current collecting member 50 (50a, 50b) by the outer can 70 and the sealing plate 80. It has become a state. For this reason, the positive electrode 10 connected to the current collecting member 50 a and the negative electrode 20 connected to the current collecting member 50 b are also fixed in the outer container 60.

  Furthermore, in the first embodiment, pressing force is applied to the current collecting members 50a and 50b by the outer can 70 and the sealing plate 80, while the electrode group 40 (the positive electrode 10 and the negative electrode 20) has a stacking direction ( (Z direction) is configured so that no pressing force is applied. That is, in the first embodiment, as shown in FIGS. 10 and 17, the positive electrode active material layer 12 (formation region N of the positive electrode active material layer 12) and the negative electrode active material layer 22 (formation region M of the negative electrode active material layer 22). The electrode group 40 (the positive electrode 10 and the negative electrode 20) is fixed in the outer container 60 via the current collecting member 50 (50a, 50b) in a state in which no pressing force is applied to.

  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.

  In the lithium ion secondary battery 100 according to the first embodiment, as described above, the electrode group 40 (the positive electrode 10 and the negative electrode 20) is fixed in the outer container 60 in a state where no pressing force is applied to the active material layer. Thereby, the position shift of the positive electrode 10 and the negative electrode 20 can be suppressed. Thereby, cycle characteristics can be improved. Therefore, by configuring as described above, life characteristics and reliability can be improved.

  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, by preventing the pressing force from being applied to the positive electrode active material layer 12 and the negative electrode active material layer 22, in the formation process (cutting process) of the positive electrode 10 and the negative electrode 20, Even when burr protrusions are generated on the cut surfaces of the positive electrode 10 and the negative electrode 20, it is possible to prevent the positive electrode 10 and the negative electrode 20 from being short-circuited by the burr protrusions. 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. Therefore, by configuring as described above, a large-capacity lithium ion secondary battery 100 can be obtained with a high yield.

  Further, in the first embodiment, by preventing the pressing force from being applied to the positive electrode active material layer 12 and the negative electrode active material layer 22, even when protrusions are formed at the application start end and application end of the active material layer. And it can suppress that pressing force is added to such a protrusion part. 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, the current collection member 50a connected with the collector exposed part 11a of the positive electrode 10 and the current collection member 50b connected with the current collector exposed part 21a of the negative electrode 20 are provided, These current collection members By fixing the positive electrode 10 and the negative electrode 20 in the outer container 60 through 50a and 50b, the outer container can be easily applied in a state where no pressing force is applied to the positive electrode active material layer 12 and the negative electrode active material layer 22. The positive electrode 10 and the negative electrode 20 can be fixed in 60.

  In the first embodiment, by forming the current collecting member 50 (50a, 50b) so as to have the comb-like connection pieces 52 connected to the current collector exposed portions 11a and 21a, The current collecting member 50 (50a, 50b) can be connected and fixed to the positive electrode 10 and the negative electrode 20. Thereby, the said electrode group (the positive electrode 10 and the negative electrode 20) can be easily fixed in the exterior container 60 via the current collection member 50 (50a, 50b). Thereby, the electrode group 40 (the positive electrode 10 and the negative electrode 20) can be fixed in the outer container 60 in a state where no pressing force is applied to the positive electrode active material layer 12 and the negative electrode active material layer 22. . As a result, the displacement of the positive electrode 10 and the negative electrode 20 can be more effectively suppressed while suppressing the pressing force from being applied to the positive electrode active material layer 12 and the negative electrode active material layer 22.

  Furthermore, in the first embodiment, the current collecting members 50a and 50b can be easily fixed by applying a pressing force to the current collecting members 50a and 50b by the outer can 70 and the sealing plate 80. The positive electrode 10 and the negative electrode 20 can be easily fixed in the outer container 60 via the current collecting members 50a and 50b. Thereby, the position shift of the positive electrode 10 and the negative electrode 20 can be effectively suppressed while suppressing the pressing force from being applied to the positive electrode active material layer 12 and the negative electrode active material layer 22. As a result, the cycle characteristics can be effectively improved and the occurrence of an internal short circuit can be effectively suppressed.

  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.

(Modification of the first embodiment)
FIG. 19 is a perspective view schematically showing an electrode group of a lithium ion secondary battery according to a modification of the first embodiment. In FIG. 19, the electrode group 40 in a state where the current collecting member 50 is connected is schematically shown. Next, a lithium ion secondary battery according to a modification of the first embodiment will be described with reference to FIG. Note that, in FIG. 19, corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  In the lithium ion secondary battery according to the modification of the first embodiment, as shown in FIG. 19, the connecting piece 52 of the current collecting members 50a and 50b is screwed to the current collector exposed portion 11a of the positive electrode current collector 11. And the current collector exposed portion 21a of the negative electrode current collector 21 are connected and fixed.

  Specifically, the current collector is exposed between the connection pieces 52 of the current collector 50 (50a, 50b) and the current collector exposed portions 11a and 21a between the connection pieces 52 of the current collector 50 (50a, 50b). A through hole (not shown) communicating in the stacking direction (Z direction) is formed in a state where the portions 11a and 21a are inserted. Then, when the screw 110 is inserted into the through hole and tightened, the connection piece 52 of the current collecting members 50 a and 50 b is connected to the current collector exposed portion 11 a of the positive electrode current collector 11 and the current collector 21. It is connected and fixed to the electric body exposed portion 21a. At this time, the screw 110 may be tightened through a washer, a spacer, or the like as necessary. In the modification of the first embodiment, screws are fixed at two locations.

  Other configurations of the modified example of the first embodiment are the same as those of the first embodiment. The effect of the modification of the first embodiment is the same as that of the first embodiment.

(Second Embodiment)
FIG. 20 is an exploded perspective view of a lithium ion secondary battery according to the second embodiment of the present invention, and FIG. 21 is a cross-sectional view of a current collecting member of the lithium ion secondary battery according to the second embodiment of the present invention. . FIG. 22 is a side view schematically showing an electrode group of the lithium ion secondary battery according to the second embodiment of the present invention, and FIG. 23 schematically shows the lithium ion secondary battery according to the second embodiment of the present invention. FIG. 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, 11 and 20 to 23. 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 FIGS. 20 and 21, in the configuration of the first embodiment, the height h2 of the current collecting member 250 (height h2 of the main body 251). However, it is comprised so that it may become smaller than the height h1 (refer FIG. 11) of the current collection member 50 of the said 1st Embodiment. Specifically, in the second embodiment, the height h2 of the current collecting member 250 is configured to be about 10 mm to about 11 mm, for example.

  As shown in FIG. 23, the current collecting member 250 includes a positive current collecting member 250 a connected to the positive electrode 10 and a negative current collecting member 250 b connected to the negative electrode 20. . As shown in FIG. 21, the current collecting member 250 has the same configuration as the current collecting member 50 of the first embodiment shown in FIG. 11 except that the height h2 of the main body 251 is small. Have.

  In the second embodiment, as shown in FIG. 20 and FIG. 23, a convex portion 85 is formed on the panel portion 81 of the sealing plate 80 so as to protrude toward the current collecting member 250 (in the Z direction). 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 (see FIG. 23). Further, the convex portions 85 of the sealing plate 80 are formed at two positions of the panel portion 81 so as to correspond to the respective main body portions 251 of the current collecting members 250 (250a, 250b). It is formed in an elongated shape so as to extend along the main body 251. In FIG. 23, the description of the separator is omitted.

  Further, similarly to the sealing plate 80, a convex portion 76 that protrudes toward the current collecting member 250 (in the Z direction) is formed on the bottom surface portion 71 of the outer can 70. The convex portion 76 is formed integrally with the bottom surface portion 71 of the outer can 70 and has a substantially flat pressing surface 76a. The pressing surface 76 a of the convex portion 76 is formed in substantially the same shape as the pressing surface 85 a of the convex portion 85 formed on the sealing plate 80. That is, the convex portions 76 of the outer can 70 are also formed at two locations on the bottom surface portion 71 so as to correspond to the main body portion 251 of the current collecting member 250 and extend along the main body portion 251 of the current collecting member 250. It is formed in an elongated shape.

  Then, by attaching the sealing plate 80 to the outer can 70, as shown in FIG. 23, the current collecting member 250 (250a, 250b) is formed by the convex portion 85 of the sealing plate 80 and the convex portion 76 of the outer can 70. A pressing force is applied to the main body 251. Thus, the current collecting members 250a and 250b are fixed in the outer container 60, and the positive electrode 10 (see FIG. 23) connected to the current collecting member 250a and the negative electrode connected to the current collecting member 250b. 20 (see FIG. 23) is also fixed in the outer container 60.

  In the second embodiment, as shown in FIGS. 22 and 23, a pressing force is applied to the current collecting member 250 (250a, 250b) by the convex portion 85 of the sealing plate 80 and the convex portion 76 of the outer can 70. On the other hand, even when the height h2 (see FIG. 21) of the current collecting member 250 is small, the electrode group 40 (the positive electrode 10 and the negative electrode 20) is configured not to be pressed. Therefore, in the second embodiment, as in the first embodiment, current collection is performed in a state where no pressing force is applied to the positive electrode active material layer 12 (see FIG. 7) and the negative electrode active material layer 22 (see FIG. 9). The electrode group 40 (the positive electrode 10 and the negative electrode 20) is fixed in the outer container 60 through the member 250.

  Other configurations of the second embodiment are the same as those of the first embodiment. In addition, as in the modification of the first embodiment, the connecting piece 52 of the current collecting member 250 (250a, 250b) is screwed to the current collector exposed portion 11a (see FIG. 6) of the positive electrode current collector 11 (see FIG. 6). It is also possible to connect and fix to the current collector exposed portion 21a (see FIG. 8) of the negative electrode current collector 21 (see FIG. 8).

  In 2nd Embodiment, as mentioned above, by forming the convex parts 85 and 76 in the sealing plate 80 and the exterior can 70, respectively, the current collecting member 250 (250a, 250b) is formed by the convex parts 85 and 76. Can be easily pressed. For this reason, the current collection member 250 (250a, 250b) can be easily fixed in the exterior container 60 by pressing the current collection member 250 (250a, 250b) with the convex portions 85 and 76. As a result, the electrode group 40 (the positive electrode 10, the positive electrode 10, the positive electrode 10, and the negative electrode active material layer 22 is not easily applied to the positive electrode active material layer 12 and the negative electrode active material layer 22 through the current collecting members 250 a and 250 b. The negative electrode 20) can be fixed.

  Further, in the second embodiment, by pressing the current collecting member 250 with the convex portions 85 and 76, even when the active material layer expands and contracts due to charge / discharge, a pressing force is not applied to the active material layer. Can be configured.

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

(Modification of the second embodiment)
FIG. 24 is a side view schematically showing an electrode group of a lithium ion secondary battery according to a modification of the second embodiment. FIG. 25 is a cross-sectional view schematically showing a lithium ion secondary battery according to a modification of the second embodiment. FIG. 24 schematically shows the electrode group 40 in a state where the current collecting member 250 is connected. In FIG. 25, the separator is omitted. Next, with reference to FIG. 24 and FIG. 25, the lithium ion secondary battery by the modification of 2nd Embodiment is demonstrated. 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 according to the modification of the second embodiment, the current collecting member 250 (250a, 250b) is formed by the convex portion 85 of the sealing plate 80 and the convex portion 76 of the outer can 70, as shown in FIGS. ) In the Z direction is applied to the connecting piece 52. Thereby, in the exterior container 60, the electrode group 40 (the positive electrode 10 and the negative electrode 20) is fixed together with the current collecting members 250a and 250b.

  In this case, the connecting piece 52 of the current collecting member 250 (250a, 250b) is exposed to the current collector exposed portion 11a of the positive electrode current collector 11 and the current collector exposed to the negative electrode current collector 21 by welding or screwing. Even if it is not fixed to the portion 21a, it is possible to suppress the displacement of the positive electrode 10 and the negative electrode 20. However, the connection piece 52 of the current collector 250 (250a, 250b) is connected to the current collector exposed portion 11a of the positive electrode current collector 11 and the current collector exposed portion 21a of the negative electrode current collector 21 by welding or screwing. The connection may be fixed. As in the modification of the first embodiment, the connection pieces 52 of the current collecting members 250a and 250b are connected to the current collector exposed portion 11a of the positive electrode current collector 11 and the current collector exposed to the negative electrode current collector 21 by screwing. When connecting and fixing to the portion 21a, the current collecting member 250 may be fixed by applying a pressing force to the screw portion (head portion of the screw). Alternatively, the current collecting member 250 and the electrode (electrode group 40) may be fixed by avoiding the screwing portion and configuring the connecting piece 52 to be pressed.

  Other configurations of the modified example of the second embodiment are the same as those of the second embodiment. The effect of the modification of the second embodiment is the same as that of the first and second embodiments.

(Third embodiment)
FIG. 26 is a cross-sectional view of a current collecting member of a lithium ion secondary battery according to the third embodiment of the present invention, and FIG. 27 is an exploded view of the current collecting member of the lithium ion secondary battery according to the third embodiment of the present invention. It is a perspective view. FIG. 28 is an exploded perspective view showing a part of the electrode group of the lithium ion secondary battery according to the third embodiment of the present invention, and FIG. 29 shows the lithium ion secondary battery according to the third embodiment of the present invention. It is the perspective view which showed the electrode group typically. 28 and 29 schematically show the electrode group 40 with the current collecting member 350 connected thereto. Next, with reference to FIGS. 26-29, the lithium ion secondary battery by 3rd Embodiment of this invention is demonstrated. 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 according to the third embodiment, as shown in FIGS. 26 and 27, unlike the first and second embodiments, the current collecting member 350 in which each connection piece 52 is formed separately. It has. The current collecting member 350 includes a plurality of plate-like members 310 having step portions 311, and the plurality of plate-like members 310 are connected by screws 320 and nuts 330. The plate-like member 310 has a thin plate portion 312 having a small thickness, which is a bottom surface portion of the step portion 311, and a thick plate portion 313 having a thickness larger than that of the thin plate portion 312. It functions as the connection piece 52 of the member 350. On the other hand, a through-hole 313a penetrating in the thickness direction is formed in a predetermined region of the thick plate portion 313. A screw 320 is inserted into the through-hole 313a and tightened, whereby one current collecting member 350 is formed. Is assembled. Note that the thick plate portion 313 is connected by the screw 320, whereby the main plate portion 351 of the current collecting member 350 is configured by the connected thick plate portion 313. In the third embodiment, the thick plate portion 313 is fixed by screws.

  Thus, in the lithium ion secondary battery according to the third embodiment, since the connection piece 52 (plate-like member 310) of the current collecting member 350 is formed as a separate body, as shown in FIG. 10 and the negative electrode 20) can be assembled to the current collecting member 350 (see FIGS. 26 and 27) after the connection piece 52 is connected and fixed in advance to the current collector exposed portion 11a (21a) of the negative electrode 20). Thereby, as shown in FIG. 29, the current collecting member 350 can be easily connected and fixed to the electrode (electrode group 40). Note that the current collecting member 350 includes a positive electrode current collecting member 350a connected to the positive electrode (current collector exposed portion of the positive electrode current collector) and a negative electrode (negative electrode current collector), as in the first and second embodiments. And a current collecting member 350b for a negative electrode connected to the current collector exposed portion of the electric body.

  The configuration other than the current collecting member 350 of the third embodiment is the same as that of the first or second embodiment.

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

(First Modification of Third Embodiment)
FIG. 30 is a perspective view schematically showing an electrode group of a lithium ion secondary battery according to a first modification of the third embodiment. In FIG. 30, the electrode group 40 in a state where the current collecting member 350 is connected is schematically shown. Next, with reference to FIG. 17, FIG. 28 and FIG. 30, a lithium ion secondary battery according to a first modification of the third embodiment will be described. In FIG. 30, corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  In the lithium ion secondary battery according to the first modification of the third embodiment, as shown in FIG. 30, a step portion 340 is formed in the main body portion 351 of the current collecting member 350, and the bottom portion of the step portion 340 is screwed. It has been stopped. Accordingly, the head of the screw 320 is configured not to protrude from the upper surface of the main body 351, and the nut 330 (see FIG. 28) is configured not to protrude from the lower surface of the main body 351.

  Other configurations of the first modification of the third embodiment are the same as those of the third embodiment.

  In the first modification of the third embodiment, as described above, the sealing plate is configured such that the head portion of the screw 320 and the nut 330 (see FIG. 28) do not protrude from the main body portion 351 of the current collecting member 350. When the pressing force is applied to the main body 351 of the current collecting member 350 by 80 (see FIG. 17) and the outer can 70 (see FIG. 17), the sealing plate 80 (see FIG. 17) and the outer can 70 (see FIG. 17) The contact area of the current collecting member 350 with the main body 351 can be increased. Accordingly, as shown in FIG. 17, the current collecting member 350 can be easily fixed in the outer container 60, and it is possible to make it difficult for the current collecting member 350 to be displaced.

  Other effects of the first modification of the third embodiment are the same as those of the third embodiment.

(Second Modification of Third Embodiment)
FIG. 31 is a plan view of a current collecting member of a lithium ion secondary battery according to a second modification of the third embodiment. FIG. 32 is a side view in the B direction of FIG. Next, with reference to FIG. 31 and FIG. 32, the lithium ion secondary battery by the 2nd modification of 3rd Embodiment is demonstrated. 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 according to the second modification of the third embodiment, as shown in FIGS. 31 and 32, the current collecting member 350 (plate member 310) is integrated by a clip 360. As in the first modification of the third embodiment, the current collecting member 350 has a step portion 340 formed in the main body portion 351, and a plurality of plate-like members 310 are integrally formed in the step portion 340. It is fixed.

  Other configurations of the second modification of the third embodiment are the same as those of the first modification of the third embodiment. Moreover, you may make it the structure which does not provide a level | step-difference part in the main-body part 351 of the current collection member 350 like the said 3rd Embodiment.

  In the second modification of the third embodiment, as described above, the current collecting member 350 (plate-like member 310) is integrated with the clip 360, so that a screw is formed as in the first modification of the third embodiment. Since there is no need to provide holes (through holes), the number of manufacturing steps can be reduced accordingly.

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

(Fourth embodiment)
FIG. 33 is a perspective view schematically showing an electrode group of the lithium ion secondary battery according to the fourth embodiment of the present invention. FIG. 34 is a plan view of an electrode group of a lithium ion secondary battery according to a fourth embodiment of the present invention. FIG. 35 is an exploded perspective view showing a part of an electrode group of a lithium ion secondary battery according to a fourth embodiment of the present invention. 33 and 34 schematically show the electrode group 40 with the current collecting member 450 connected thereto. Next, with reference to FIGS. 33-35, the lithium ion secondary battery by 4th Embodiment of this invention is demonstrated. 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 according to the fourth embodiment, a current collecting member 450 is constituted by a plurality of strip-shaped metal plates 410 as shown in FIGS. The metal plate 410 constituting the current collecting member 450 has substantially the same size as the current collector exposed portions 11a and 21a, and a through hole 411 penetrating in the thickness direction is formed in each predetermined region. . In addition, a similar through hole 11b is formed in the current collector exposed portion 11a (21a) of the electrode (positive electrode 10, negative electrode 20) at a position corresponding to the through hole 411 of the metal plate 410. In addition, the said current collection member 450 is the same as the said 1st-3rd embodiment, The current collection member 450a for positive electrodes connected to a positive electrode (current collector exposed part of a positive electrode current collector), and a negative electrode (negative electrode current collection). And a current collecting member 450b for a negative electrode connected to a current collector exposed portion of the electric body). The metal plate 410 constituting the positive electrode current collector member 450a is formed in substantially the same size as the current collector exposed portion 11a of the positive electrode current collector, and the metal plate 410 constituting the negative electrode current collector member 450b. Is formed in substantially the same size as the current collector exposed portion 21a of the negative electrode current collector.

  As shown in FIG. 35, one metal plate 410 (410a) is disposed between adjacent electrodes (positive electrode 10 and negative electrode 20). The thickness of the metal plate 410a disposed between the electrodes is preferably configured to be equal to the distance between adjacent electrodes. On the other hand, the metal plate 410 (410b) disposed on the outermost side of the current collecting member 450 is formed to have a thickness that is equal to or greater than the thickness of the metal plate 410a disposed between the electrodes. preferable. The specific thickness of the metal plate 410b disposed on the outermost side of the current collecting member 450 can be set to, for example, about 1 mm to 2 mm.

  The plurality of metal plates 410 are connected by screws 420 and nuts 430. The current collecting member 450 is configured by integrating the plurality of metal plates 410. At this time, the screws 420 are inserted into the through holes 411 and 11b and tightened, so that the current collecting member 450 (450a, 450b) is connected to the current collector exposed portion 11a of the positive electrode current collector and the negative electrode current collector. It is connected and fixed to the current collector exposed portion 21a. In the fourth embodiment, the current collecting member 450 (metal plate 410) is fixed with screws at two locations.

  As described above, the current collecting member 450 of the lithium ion secondary battery according to the fourth embodiment is composed of the metal plate 410 functioning as a connection piece. Unlike the first to third embodiments, the main body portion is arranged. It has a configuration that does not have. For this reason, the storage space for the current collecting member 450 in the exterior container can be reduced by the amount that does not include the main body.

  Configurations other than the current collecting member 450 of the fourth embodiment are the same as those of the first and second embodiments.

(Modification of the fourth embodiment)
FIG. 36 is a plan view of an electrode group of a lithium ion secondary battery according to a modification of the fourth embodiment. In FIG. 36, the electrode group 40 in a state where the current collecting member 450 is connected is schematically shown. Next, with reference to FIG. 36, the lithium ion secondary battery by the modification of 4th Embodiment is demonstrated. In FIG. 36, corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  In the modification of the fourth embodiment, as shown in FIG. 36, the length in the Y direction of the metal plate 410 constituting the current collecting member 450 is longer than the length in the Y direction of the current collector exposed portion 11a (21a). It is configured to be long. A through hole (not shown) penetrating in the thickness direction is formed in one end and the other end of the metal plate 410 in the Y direction. The through hole is formed in a region that does not overlap with the current collector exposed portion 11a (21a) when seen in a plan view. Therefore, in the modified example of the fourth embodiment, unlike the fourth embodiment, the through-hole into which the screw 420 is inserted into the current collector exposed portion 11a (21a) of the electrode (positive electrode 10, negative electrode 20). Is not formed. Then, when the screw 420 is inserted and tightened into the through hole (not shown), the current collector member 450 is exposed to the current collector exposed portion 11a of the positive electrode current collector and the current collector exposed to the negative electrode current collector. It is fixedly connected to the portion 21a.

  Other configurations of the modified example of the fourth embodiment are the same as those of the fourth embodiment.

  In the modification of the fourth embodiment, by configuring the current collector member 450 as described above, the current collector member 450 can be connected to the positive electrode current collector without forming a through hole in the current collector exposed portion 11a (21a). The current collector exposed portion 11a of the body and the current collector exposed portion 21a of the negative electrode current collector can be connected and fixed. For this reason, since it is not necessary to form a through-hole in the electrical power collector exposure part 11a (21a), a manufacturing man-hour can be reduced by that much.

  Other effects of the modified example of the fourth embodiment are the same as those of the fourth embodiment.

(Fifth embodiment)
FIG. 37 is an exploded perspective view of a lithium ion secondary battery according to a fifth embodiment of the present invention. FIG. 38 is a plan view of an electrode group of a lithium ion secondary battery according to a fifth embodiment of the present invention. Next, with reference to FIG. 10, FIG. 37 and FIG. 38, a lithium ion secondary battery according to a fifth embodiment of the present invention will be described. 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 according to the fifth embodiment, as shown in FIGS. 37 and 38, strip-shaped collectors are respectively formed on 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. A power tab 550 is connected. The current collecting tab 550 is an example of the “current collecting member” in the present invention.

  In the fifth embodiment, the current collecting tab 550 is electrically connected to the electrode terminal 74 of the outer can 70. As shown in FIG. 37, the sealing plate 80 and the outer can 70 are respectively provided with convex portions 85 and 76 similar to those of the second embodiment. A pressing force is applied to the current collector exposed portions 11 a and 21 a, which are attachment regions of the current collecting tab 550, by the convex portion 85 of the sealing plate 80 and the convex portion 76 of the outer can 70.

  Furthermore, in the fifth embodiment, as in the first to fourth embodiments, the electrode group 40 (the positive electrode 10 and the negative electrode 20) is configured such that no pressing force is applied in the stacking direction (Z direction). . That is, in the fifth embodiment, the positive electrode active material layer 12 (formation region N of the positive electrode active material layer 12 (see FIG. 10)) and the negative electrode active material layer 22 (formation region M of the negative electrode active material layer 22 (see FIG. 10)). The electrode group 40 (the positive electrode 10 and the negative electrode 20) is fixed in the outer container 60 in a state where no pressing force is applied to the outer container 60).

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

  The effects of the fifth embodiment are the same as those of the first embodiment.

  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 and 2 and the lithium ion secondary battery according to Comparative Example 1 corresponding to the first and second embodiments, respectively, were produced. FIGS. 39 and 40 are partial cross-sectional views showing simplified lithium ion secondary batteries according to Examples 1 and 2, respectively. FIG. 41 shows a simplified lithium ion secondary battery according to Comparative Example 1. FIG.

<Example 1>
In Example 1, as shown in FIG. 39, a pressing force is applied to the main body of the current collecting member 50 by the sealing plate 80 and the outer can 70, and the positive electrode 10 and the negative electrode 20 are connected to the outer container via the current collecting member 50. 60 to be fixed within. However, the positive electrode 10 (positive electrode active material layer) and the negative electrode 20 (negative electrode active material layer) were configured so that no pressing force was applied. In Example 1, the connecting piece of the current collecting member 50 and the current collector exposed portion were connected and fixed by ultrasonic welding. The current collecting member 50 was made of aluminum on the positive electrode side and copper on the negative electrode side.

<Example 2>
In Example 2, as shown in FIG. 40, convex portions 85 and 76 are formed on the sealing plate 80 and the outer can 70, respectively, so that a pressing force is applied to the current collecting member 250 by the convex portions 85 and 76. Configured. However, as in Example 1, the positive electrode 10 (positive electrode active material layer) and the negative electrode 20 (negative electrode active material layer) were configured so that no pressing force was applied. In Example 2, as in Example 1, the connecting piece of the current collecting member 250 and the current collector exposed portion were connected and fixed by ultrasonic welding. The current collecting member 250 was made of aluminum on the positive electrode side and copper on the negative electrode side, as in Example 1.

<Comparative example 1>
In the comparative example 1, as shown in FIG. 41, it was comprised so that pressing force might not be applied to either a current collection member or an electrode. That is, in Comparative Example 1, the positive electrode 10 and the negative electrode 20 are not fixed in the outer container 60. In Comparative Example 1, the same current collecting member 250 as in Example 2 was used. Further, the connecting piece of the current collecting member 250 and the current collector exposed portion were connected and fixed with screws.

<Common to Examples 1 and 2 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 electrode (positive electrode plate) of Examples 1 and 2 and Comparative Example 1 was produced 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 and 2 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.

  Moreover, the connection piece of the current collection member was connected to the collector exposure part of a positive electrode, and the collector exposure part of a negative electrode, respectively.

  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 is 164 mm long, 228 mm wide, and 20 mm deep.

  And after accommodating an electrode group (laminated body) and the current collection member in this exterior can, the sealing board was mounted and the battery was sealed by double winding. In Examples 1 and 2, the sealing plate is attached so that a pressing force is applied to the current collecting member. The pressing force applied to the current collecting member was a pressing force capable of fixing the current collecting member. On the other hand, in the comparative example 1, it was comprised so that pressing force might not be applied to a current collection member, when a sealing board was attached.

  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 and 2 and Comparative Example 1 were produced.

  The lithium secondary battery batteries according to Examples 1 and 2 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 (the 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-50Hz. 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, the positive electrode and the negative electrode are fixed in the outer container via the current collecting member in a state where no pressing force is applied to the positive electrode (positive electrode active material layer) and the negative electrode (negative electrode active material layer). In Examples 1 and 2, it was confirmed that the number of defective batteries generated was reduced as compared with Comparative Example 1 in which the positive electrode and the negative electrode were not fixed. Specifically, in Example 1, the number of defective batteries was one, and in Example 2, the number of defective batteries was 0, whereas in Comparative Example 1, the number of defective batteries was five. As a result, the number of occurrences was very high. This is considered to be because, in Examples 1 and 2, it is difficult for an internal short circuit due to a burr protrusion or the like to occur because no pressing force is applied to the positive electrode active material layer and the negative electrode active material layer. It is done. In Comparative Example 1 as well, no pressing force is applied to the positive electrode active material layer and the negative electrode active material layer. However, in Comparative Example 1, since the positive electrode and the negative electrode are not fixed, the position of the electrode is shifted during battery assembly. It is thought that it is easy to occur. And since it becomes easy to generate | occur | produce an internal short circuit due to the position shift of the electrode at the time of battery assembly, it is thought that the number of defective batteries increased compared with the Example.

  Further, in Examples 1 and 2, 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 92%, and in Example 2, the capacity retention after 200 cycles was 90%. It was. As described above, the reason why the high capacity retention ratio was obtained in Examples 1 and 2 is that the positive electrode and the negative electrode are fixed through the current collecting member by applying a pressing force to the current collecting member. This is thought to be because the positional deviation between the positive electrode and the negative electrode was prevented. On the other hand, in Comparative Example 1, the capacity retention rate was 81%, 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 the first comparative example, unlike the example, no pressing force is applied to the current collecting member. Therefore, the positive electrode and the negative electrode are not fixed, and the positive electrode and the negative electrode are easily misaligned. It is considered that the capacity retention after 200 cycles was lowered.

  Further, in Examples 1 and 2, it was confirmed that the capacity retention after the vibration test was improved as compared with Comparative Example 1. Specifically, in Examples 1 and 2, the capacity retention after the vibration test was 99%, and almost no capacity reduction was observed. On the other hand, in Comparative Example 1, the capacity retention after the vibration test was 90%, and the capacity retention due to vibration was significantly reduced. This is considered to be because in Examples 1 and 2, since the positive electrode and the negative electrode are fixed in the outer container, the positional displacement of the electrodes is less likely to occur due to vibration. On the other hand, in Comparative Example 1, since the positive electrode and the negative electrode are not fixed in the outer container, the electrode is displaced with respect to vibration, which is considered to decrease the capacity retention rate.

  As described above, by fixing the electrodes (positive electrode and negative electrode) in the outer container in a state where no pressing force is applied to the positive electrode (positive electrode active material layer) and the negative electrode (negative electrode active material layer), the yield and lifetime are increased. It was confirmed that characteristics and reliability 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 fifth embodiments (including modifications), an example in which the present invention is applied to a stacked lithium ion secondary battery has been described. However, the present invention is not limited to this, for example, winding The present invention may be applied to a lithium ion secondary battery.

  Moreover, in the said 1st-5th embodiment (a modification is included), although the example which applied this invention to the lithium ion secondary battery (nonaqueous electrolyte secondary battery) which is an example of a secondary battery was shown, The present invention is not limited to this, and 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.

  Moreover, in the said 1st-5th embodiment (a modification is included), although the example which formed the active material layer on both surfaces of the electrical power collector was shown, this invention is not restricted to this, On the single surface of an electrical power collector. Only the active material layer may be formed. 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-5th embodiment (a modification is included), although the example which used non-aqueous electrolyte as an electrolyte of a secondary battery was shown, this invention is not limited to this, Other than non-aqueous electrolyte For example, a gel electrolyte, a solid polymer electrolyte, an inorganic solid electrolyte, a molten salt, or the like may be used as the electrolyte.

  Moreover, in the said 1st-5th embodiment (a modification is included), although the example which double-sealed the opening part of the exterior can with the sealing board was shown, this invention is not limited to this, The exterior can The sealing method may be a method other than the double wrap sealing. For example, the outer can may be sealed by welding the sealing plate to the outer can.

  In the first to fifth embodiments (including modifications), the negative electrode (negative electrode active material layer) is configured to be larger than the positive electrode (positive electrode active material layer). The invention is not limited to this, and 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 than the negative electrode (negative electrode active material layer)). The active material layer) may be configured to be larger.

  In addition, in the said 1st-5th embodiment (a modification is included), about the magnitude | size, shape, etc. of an exterior container, it can change variously. In addition, the configurations of the first to fifth embodiments (including modifications) described above can be combined as appropriate.

  Moreover, in the said 1st-4th embodiment (a modification is included), although the example which attached the current collection member to both the positive electrode and the negative electrode was shown, this invention is not restricted to this, One of a positive electrode and a negative electrode is shown. Only the current collecting member may be attached. In this case, the electrode to which the current collecting member is not attached is preferably configured so as not to be displaced by using a method such as applying a pressing force to the current collector exposed portion.

  Moreover, in the said 1st-4th embodiment (a modification is included), although the example comprised so that an electrode was fixed via a current collection member was shown, this invention is not restricted to this, A sealing board and exterior You may comprise so that an electrode may be fixed without interposing a current collection member by applying pressing force to the collector exposed part of an electrode with a can. In this case, in order to suppress the pressing force from being applied to the active material layer of the electrode, by increasing the length in the X direction of the current collector exposed portion, a region away from the active material layer in the current collector exposed portion It is preferable that a pressing force is applied to the.

  Moreover, in the said 1st-4th embodiment (a modification is included), the example which fixed the current collection member in the exterior container was shown by applying pressing force to a current collection member with an exterior can and a sealing board. However, the present invention is not limited to this, and the current collecting member may be fixed in the outer container by a method other than the method of applying a pressing force to the current collecting member with the outer can and the sealing plate. For example, the current collecting member may be fixed in the outer container using an adhesive or the like.

  In the first to fourth embodiments (including modifications), a rib for preventing displacement is provided on at least one of the sealing plate and the outer can in order to suppress displacement of the current collecting member. Alternatively, a groove portion into which the current collecting member is fitted may be provided.

  In the modification of the first embodiment, the connection piece of the current collecting member and the current collector exposed portion of the electrode are screwed and fixed at two locations, but the present invention is not limited thereto, It may be fixed with screws at one place or three or more places. Further, in the third and fourth embodiments (including the modified examples), when assembling the current collecting member, an example in which screws are fixed at two locations has been shown, but the present invention is not limited to this, and the first embodiment As in the modified example, it may be fixed with screws at one place or three or more places. In addition, when performing such screwing fixation, you may make it tighten a screw via a washer, a spacer, etc. as needed.

  Moreover, in the said 2 embodiment, although the example which formed the convex part in both the sealing board and the exterior can was shown, this invention is not limited to this, It seems that a convex part is formed only in one of a sealing board and an exterior can. It may be.

  Moreover, in the said 2 embodiment, although the example which formed the convex part integrally in the sealing board and the exterior can was shown, this invention is not restricted to this, You may form the said convex part separately.

  Moreover, in the said 2nd Embodiment, although the example comprised so that pressing force might be applied to a current collection member with the convex part formed in the sealing plate and the exterior can, this invention is not restricted to this, A sealing plate and exterior This insulating member is formed by interposing an insulating member having a predetermined thickness between at least one of the sealing plate and the current collecting member and between the outer can and the current collecting member without forming a convex portion on the can. For example, a pressing force may be applied to the current collecting member through the like.

  In the second embodiment, the shape or size of the convex portion can be variously changed within a range in which the current collecting member can be pressed. Further, the protruding amount of the convex portion can be appropriately adjusted so that a desired pressing force is applied to the current collecting member.

  Moreover, in the 1st modification of the said 3rd Embodiment, although the step part was formed in the main-body part of a current collection member, the example comprised so that the head part and nut of a screw might not protrude from a main-body part was shown. In addition to the stepped portion, for example, a counterbore process or the like may be performed so that the screw and the nut do not protrude from the main body portion of the current collecting member.

  Moreover, in the said 4th Embodiment (a modification is included), although the example assembled to the current collection member by screwing and fixing a some metal plate was shown, this invention is not limited to this, 3rd Embodiment As shown in the second modified example, the current collecting member may be assembled by fixing a plurality of metal plates using clips or the like. In the third embodiment (including modifications), the current collector exposed portion of the electrode may be sandwiched vertically using two metal plates arranged on the outermost side of the current collecting member. Good.

5 Current collector lead 10 Positive electrode (electrode)
DESCRIPTION OF SYMBOLS 11 Positive electrode collector 11a Current collector exposed part 11b Through-hole 12 Positive electrode active material layer 20 Negative electrode (electrode)
DESCRIPTION OF SYMBOLS 21 Negative electrode collector 21a Current collector exposed part 22 Negative electrode active material layer 30 Separator 40 Electrode group 40a Laminate 50, 250, 350, 450 Current collecting member 50a, 250a, 350a, 450a Current collecting member for positive electrode (first Current collector)
50b, 250b, 350b, 450b Current collecting member for negative electrode (second current collecting member)
51,251,351 Main body 52 Connection piece 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 76, 85 Convex part 76a, 85a Press surface 80 Sealing plate (sealing body)
81 Panel part 82 Chuck wall part 83 Folding part 84 Injection hole 100, 200 Lithium ion secondary battery (secondary battery)
110, 320, 420 Screw 310 Plate member 311 Stepped portion 312 Thin plate portion 313 Thick plate portion 360 Clip 410, 410a, 410b Metal plate 411 Through hole 550 Current collecting tab (current collecting member)

Claims (13)

An electrode including an active material layer;
An exterior container including a storage container for storing the electrode and a sealing body for sealing the storage container;
The secondary battery, wherein the electrode is fixed in the outer container in a state in which no pressing force is applied to the active material layer. A current collecting member connected to the electrode;
The secondary battery according to claim 1, wherein the electrode is fixed in the exterior container via the current collecting member.   The secondary battery according to claim 2, wherein a pressing force is applied to the current collecting member by the storage container and the sealing body. The electrode includes a positive electrode having a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, a negative electrode current collector, and a negative electrode active material layer formed on the negative electrode current collector. And including a negative electrode arranged to face the positive electrode,
The positive electrode and the negative electrode are housed in the exterior container in a state where no pressing force is applied to the positive electrode active material layer and the negative electrode active material layer, respectively. The secondary battery according to any one of 3. A current collecting member connected to the electrode;
The current collecting member includes a first current collecting member connected to the positive electrode current collector and a second current collecting member connected to the negative electrode current collector,
The secondary battery according to claim 4, wherein a pressing force is applied to each of the first current collecting member and the second current collecting member by the storage container and the sealing body. The positive electrode current collector and the negative electrode current collector each have a current collector exposed portion that is exposed without forming the positive electrode active material layer and the negative electrode active material layer,
The secondary battery according to claim 4, wherein a pressing force is applied to the current collector exposed portion by the storage container and the sealing body. A separator disposed between the positive electrode and the negative electrode;
The secondary battery according to claim 4, wherein a laminate is configured by sequentially laminating the positive electrode, the separator, and the negative electrode. The laminate has a plurality of positive electrodes and negative electrodes,
The secondary battery according to claim 7, wherein the positive electrode and the negative electrode are alternately stacked. The positive electrode current collector and the negative electrode current collector each have a current collector exposed portion that is exposed without forming the positive electrode active material layer and the negative electrode active material layer,
The secondary battery according to claim 5, wherein the current collecting member includes a comb-like connection piece connected to the current collector exposed portion.   The secondary battery according to claim 1, wherein each of the storage container and the sealing body is made of a metal material. A current collecting member connected to the electrode;
The electrode is disposed so as to face the sealing body, and the storage container includes a bottom portion facing the electrode,
The convex part which protrudes toward the said current collection member is formed in at least one of the said sealing body and the bottom face part of the said storage container, The Claim 1 characterized by the above-mentioned. Secondary battery.   The secondary battery according to claim 1, wherein at least one battery inside of the storage container and the sealing body is coated with a polymer laminate material. The storage container is formed in a square shape, and the surface with the largest area is the bottom surface part,
The secondary battery according to claim 1, wherein the electrode is stored in the storage container so as to face the bottom surface portion.

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