JP2012174452A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery having excellent heat resistance, pressure resistance, and airtightness by connecting a metallic outer body and electrode terminals by caulking.SOLUTION: A secondary battery 100 comprises an electrode group 40 comprising a positive electrode 10 and a negative electrode 20, an outer container 60 comprising an outer can 70 containing the electrode group 40 and a sealing plate 80 sealing an opening 73 of the outer can 70, a pair of electrode terminals 90 connected to the outer container 60 from outside the outer container 60 by caulking, and an electrolyte charged into the outer container 60.

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 small and light, high energy density, and can be repeatedly charged and discharged for a long time. There is a demand for a secondary battery that satisfies the following conditions. As a secondary battery that satisfies these requirements, a lithium ion secondary battery having a higher energy density than other secondary batteries is considered most promising. Various researches and developments have been conducted to develop better lithium ion secondary batteries.

In addition, in consideration of environmental problems such as global warming, lithium ion secondary batteries have been used in power storage systems used in solar power generation systems, wind power generation systems, and the like. In addition, as a measure against CO ₂ reduction and energy problems, there is an increasing expectation for the spread of hybrid vehicles (HEVs) and electric vehicles (EVs) with low fuel consumption and low exhaust gas. Development and commercialization of lithium-ion secondary batteries targeting the above are also in progress.

  Thus, the demand for lithium ion secondary batteries not only for portable devices but also for large-scale power is increasing. When a lithium ion secondary battery is used for power or an electric power storage system, it is necessary to increase the capacity in order to enable long-time discharge, and a longer life is also required.

  Lithium ion secondary batteries having various sizes and shapes have been proposed to suit these various uses. In a general lithium ion secondary battery, 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, thereby forming an electrode group. It is formed by pouring a non-aqueous electrolyte after being accommodated in the exterior body (storage container). And charging / discharging is performed by moving a lithium ion between a positive electrode and a negative electrode.

  As the shape of the electrode group, a winding type in which the electrode group is integrally wound and a laminated type in which a positive electrode, a separator, and a negative electrode are laminated in a flat plate shape are known. The wound electrode group is housed in a cylindrical can (exterior body) to form a cylindrical secondary battery (see Patent Document 1). On the other hand, the laminated electrode group may be covered with a laminate film (exterior body) to be a laminated secondary battery, or may be housed in a rectangular can to be a rectangular battery.

JP 2000-331656 A

  Such a lithium ion secondary battery generates heat and expands during charge and discharge, and thus requires heat resistance and pressure resistance. Moreover, since the electrolytic solution is enclosed, airtightness is also required. Here, in the cylindrical secondary battery, resin is used for a part of the lid which is a part of the outer package. The center part of the lid is made of metal since it becomes a positive electrode terminal, but a resin packing is used around the periphery to insulate from the outer can. Heat and pressure are also applied to the resin packing. Since the resin is weaker in heat and pressure than the metal and easily deteriorates, the durability of the secondary battery is reduced.

  In the laminate type secondary battery, since the resin surfaces of the laminate film are heat-welded, the resin is hard and brittle due to heat at the time of welding, and it is difficult to say that the durability is high.

  Moreover, in the said square battery, the electrode terminal is laser-welded to the through-hole of a metal exterior body. Since it is difficult to weld dissimilar materials by laser welding, the materials of the outer package and the electrode terminal are limited. Furthermore, since the resin containing the resin melts the resin in the vicinity of the welding by laser welding, a high-strength laminated steel sheet cannot be used as a material for the exterior body.

  An object of this invention is to provide the secondary battery excellent in heat resistance, pressure | voltage resistance, and airtightness by using the crimping technique for the connection of a metal exterior body and an electrode terminal.

  In order to achieve the above object, a secondary battery of the present invention includes an outer electrode container including an electrode group including a positive electrode and a negative electrode, a storage container that stores the electrode group, and a sealing body that seals an opening of the storage container. A pair of electrode terminals that are caulked and joined to the exterior container from the outside of the exterior container and an electrolytic solution filled in the exterior container are provided.

  According to this configuration, since the caulking technique is used for joining the outer container and the electrode terminal, it is not necessary to use heat welding or laser welding.

  The secondary battery according to claim 1, wherein the pair of electrode terminals are provided in the storage container of the outer container.

  Said secondary battery WHEREIN: It is preferable that said pair of electrode terminal is each provided in the side wall part which the said storage container opposes.

  In the above secondary battery, the pair of electrode terminals may be provided on the same side wall of the storage container.

  In the above secondary battery, the pair of electrode terminals may be provided on the sealing body of the exterior container.

  In the above secondary battery, at least one of the pair of electrode terminals includes a metal pedestal portion having a through hole, a metal terminal portion passed through the through hole, the terminal portion, and the pedestal portion. And the base part can be caulked and joined to the exterior container.

  Further, in the above secondary battery, at least one of the pair of electrode terminals includes a metal pedestal part and a metal terminal part integrally formed so as to protrude from the front and back of the pedestal part, It can be set as the structure by which a base part is caulked and joined to the said exterior container.

  Further, in the above secondary battery, the storage container is made of a double-sided laminate material in which an insulating resin is laminated on both surfaces of a metal plate, and the pair of electrode terminals includes a metal pedestal portion and front and back surfaces of the pedestal portion. And a metal terminal portion integrally formed so as to protrude into the outer casing, and the base portion can be caulked and joined to the outer container.

  Further, in the above secondary battery, the storage container is made of a single-sided laminate material in which an insulating resin is laminated on one side of a metal plate, and the one electrode terminal includes a metal first pedestal portion having a through-hole. A metal first terminal portion that is passed through the through hole, an insulating portion that insulates the first terminal portion and the first pedestal portion, and the first pedestal portion is caulked and joined, The electrode terminal has a metal second pedestal portion and a metal second terminal portion integrally formed so as to protrude from the front and back of the second pedestal portion, and the second pedestal portion is It can be set as the structure crimped and joined to an exterior container.

  In the above secondary battery, the thickness of the metal plate is preferably 0.5 mm or more and 2 mm or less.

  Further, in the above secondary battery, the storage container is made of a metal plate, and the pair of electrode terminals includes a metal base portion having a through hole, a metal terminal portion passed through the through hole, and An insulating part that insulates the terminal part and the pedestal part may be provided, and the pedestal part may be caulked and joined to the exterior container.

  In the above secondary battery, it is preferable that the caulking is a clamshell caulking.

  Further, in the above secondary battery, it is preferable that the overlap at the time of the folding is 50% or more.

  In the above secondary battery, it is preferable that the storage container and the sealing body are double-sealed.

  Moreover, in the above secondary battery, it is preferable that the overlap when performing the double-tightening sealing is 70% or more.

  According to the present invention, a secondary battery having excellent heat resistance, pressure resistance, and airtightness can be realized by caulking and joining electrode terminals. In addition, since the electrode terminals are caulked and joined from the outside of the battery, when the internal pressure of the battery rises, a force is applied to the caulking joined part in a direction that weakens the joining, and the joining strength is designed appropriately. It can also have the role of a safety valve. Also, dissimilar materials that were difficult to be welded by laser welding can be easily joined by caulking. Further, the caulking is advantageous in that the production speed is high.

It is a disassembled perspective view of the lithium ion secondary battery of 1st Embodiment of this invention. It is a disassembled perspective view of the lithium ion secondary battery of 1st Embodiment of this invention. 1 is an overall perspective view of a lithium ion secondary battery according to a first embodiment of the present invention. It is a top view of the lithium ion secondary battery of 1st Embodiment of this invention. It is the perspective view which showed the structure of the electrode group of the lithium ion secondary battery of 1st Embodiment of this invention. It is the perspective view which showed the structure of the positive electrode of the lithium ion secondary battery of 1st Embodiment of this invention. It is the top view which showed the structure of the positive electrode of the lithium ion secondary battery of 1st Embodiment of this invention. It is the perspective view which showed the structure of the negative electrode of the lithium ion secondary battery of 1st Embodiment of this invention. It is the top view which showed the structure of the negative electrode of the lithium ion secondary battery of 1st Embodiment of this invention. It is sectional drawing which showed the structure of the electrode group of the lithium ion secondary battery of 1st Embodiment of this invention. It is a perspective view of the armored can of the lithium ion secondary battery of 1st Embodiment of this invention. It is a top view of the armored can of the lithium ion secondary battery of 1st Embodiment of this invention. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is a front view of the electrode terminal of the lithium ion secondary battery of 1st Embodiment of this invention. It is the BB sectional view taken on the line of FIG. 14A. It is principal part sectional drawing of the state in which the electrode terminal before crimping joining in the lithium ion secondary battery of 1st Embodiment of this invention was attached to the exterior container. It is principal part sectional drawing of the state in which the electrode terminal in the lithium ion secondary battery of 1st Embodiment of this invention was crimped and joined to the exterior container. It is a whole perspective view of the lithium ion secondary battery of 2nd Embodiment of this invention. It is a front view of the electrode terminal of the lithium ion secondary battery of 2nd Embodiment of this invention. It is the EE sectional view taken on the line of FIG. 17A. It is a whole perspective view of the lithium ion secondary battery of 3rd Embodiment of this invention. It is a front view of the other electrode terminal of the lithium ion secondary battery of this invention. 19B is a cross-sectional view taken along line FF in FIG. 19A. It is a front view of the further another electrode terminal of the lithium ion secondary battery of this invention. It is the GG sectional view taken on the line of FIG. 20A. It is principal part sectional drawing of the state in which the electrode terminal before crimping joining in the lithium ion secondary battery of this invention was attached to the exterior container.

  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. In the present invention, caulking or caulking joining refers to joining that is crimped so as to enclose two members, as represented by brazing caulking.

(First embodiment)
1 and 2 are exploded perspective views of the lithium ion secondary battery according to the 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 top view of the lithium ion secondary battery according to the first embodiment of the present invention. FIGS. 5-15B is a figure for demonstrating the lithium ion secondary battery of 1st Embodiment of this 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.

  The lithium ion secondary battery 100 of 1st Embodiment has square flat shape (refer FIG. 3), as shown in FIGS. 1-4, and the positive electrode 10 (refer FIG. 1) and the negative electrode 20 (FIG. 1). Electrode group 40 (see FIG. 1 and FIG. 2), and an outer container 60 that encloses the electrode group 40 together with a non-aqueous electrolyte. 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 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.

  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 stacked with the separators 30 interposed therebetween.

  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, one treated with aluminum or titanium for the purpose of improving conductivity and oxidation resistance. A current collector in which two or more metal foils are bonded together can also be used. A current collector in which a metal is coated on a resin 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. As a positive electrode active material, the oxide containing lithium is mentioned, for example. 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 contain 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, etc. include 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, and water can be used.

  The positive electrode 10 described above is obtained by mixing a positive electrode active material, a conductive material, a thickening material, 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 150 mm, for example, and a length g1 in the X direction of about 320 mm, for example. In addition, 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 150 mm, and the length g11 in the X direction is, for example, About 300 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. The current collector exposed portion 11a is electrically connected to a current collector lead 5 (see FIG. 4), which will be described later, for taking out current to the outside. 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 a negative electrode active material layer 22 is supported on both surfaces of a negative electrode current collector 21.

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

  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. As the lithium transition metal oxide, for example, when lithium titanate typified by Li ₄ Ti ₅ O ₁₂ is used, the deterioration of the negative electrode 20 is reduced, so that the battery life 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 that is larger than the width w1 of the positive electrode 10 (see FIG. 7), for example, about 154 mm, and has a length g2 in the X direction. The length of the positive electrode 10 is longer than the length g1 (see FIG. 7), for example, about 324 mm.

  Further, 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 154 mm, and the length g21 in the X direction is, for example, It is about 304 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. . The current collector exposed portion 21a is electrically connected to a current collector lead 5 (see FIG. 4), which will be described later, for extracting a current to the outside. The four edge portions 23 in the negative electrode active material layer 22 are in the positive electrode 10 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 14.

  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, the separator 30 has, for example, a vertical length (a length in a direction corresponding to the X direction) of about 310 mm and a horizontal length (Y direction). Is formed in a rectangular shape having a length of about 160 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, and a separator 30 is interposed between the positive and negative electrodes. Are stacked.

  The nonaqueous electrolytic solution enclosed with the electrode group 40 in the outer container 60 is not particularly limited, but examples of the solvent include ethylene carbonate (EC), propylene carbonate, butylene carbonate, diethyl carbonate (DEC), Esters such as dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, dioxolane, diethyl ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, dimethyl sulfoxide, sulfolane, Polar solvents such as methylsulfolane, acetonitrile, methyl formate, methyl acetate can be used. These solvents may be used alone, or two or more kinds may be mixed and used as a mixed solvent.

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

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

  The exterior container 60 that encloses the electrode group 40 is a large flat rectangular container. As shown in FIGS. 1 to 3, an exterior can 70 that houses the electrode group 40 and the like, and a sealing plate that seals the exterior can 70. 80. Further, the outer can 70 in which the electrode group 40 is accommodated is sealed with a sealing plate 80 (preferably a double-tightened seal). 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 by, for example, drawing a metal plate, and has a bottom surface 71 and a side wall 72. As shown in FIGS. 11 and 12, through-holes 76 and 76 into which the electrode terminals 90 and 90 are inserted are provided in the respective side wall portions 72 parallel to the Y direction so as to face each other by punching or the like. . The through hole 76 has an elliptical shape as shown in FIG. 11, for example, and the periphery thereof is bent outward to such an extent that it can be crimped to the electrode terminal 90 to form a through hole folded portion 76 a.

  In addition, an opening 73 for inserting the electrode group 40 is provided at one end of the outer can 70 (on the side opposite to the bottom surface portion 71). The outer can 70 is formed in a rectangular can, and the area of the substantially rectangular opening 73 is larger than the area of the substantially rectangular bottom surface 71. That is, the corners 72a at the four corners of the side wall 72 are linearly expanded from the bottom surface 71 side to the opening 73 side. Furthermore, a container folding portion 75 for performing a winding sealing (preferably a double winding sealing) is provided at the periphery of the opening 73 of the outer can 70.

  The inner diameter of the outer can 70 is such that the electrode group 40 can be accommodated so that the electrode surface faces the bottom surface 71. Specifically, in the outer can 70, for example, the length in the vertical direction of the bottom surface portion 71 (the length L in the Y direction in FIG. 12) is about 180 mm. The length (length W in the X direction in FIG. 12) is about 350 mm. The depth of the outer can 70 is, for example, about 40 mm.

  The sealing plate 80 is formed, for example, by pressing a metal plate. As shown in FIG. 2, the sealing plate 80 includes a panel portion 81 having a substantially flat rectangular shape 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 And a folded portion 83 connected to the outer peripheral end of the wall portion 82. Furthermore, as shown in FIG.2 and FIG.3, the injection hole 84 for inject | pouring a non-aqueous electrolyte is formed in the one side of a 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 are made of a material resistant to an electrolytic solution, for example, a metal plate such as iron, stainless steel, or aluminum, a steel plate obtained by nickel plating on iron, a steel plate obtained by applying aluminum plating, or the like. Can be used. Since iron is an inexpensive material, it is preferable from the viewpoint of price, but in order to ensure long-term reliability, a metal plate made of stainless steel (SUS), aluminum, or the like or a steel plate in which iron is nickel-plated (Fe It is more preferable to use a steel plate (Fe—Al) or the like that is obtained by applying aluminum plating to -Ni) or iron.

  In addition to the above, a laminate material (laminate plate) obtained by laminating the surface of a metal plate with a polymer material can also be used. In this case, a single-sided laminated material laminated on one side (battery inner side or outer side) or a double-sided laminated material laminated on both sides can be appropriately used. By using the laminate material, the strength of the outer can 70 is improved as compared with the case of using only the metal plate. In addition, a metal plate that is not very resistant to the electrolytic solution can be used by laminating the outside of the battery with a polymer material that is resistant to the electrolytic solution. Further, the exterior of the battery can be suppressed by laminating the outside of the battery with a polymer material.

  In addition, the thickness of a metal plate can be about 0.5 mm-about 2 mm (for example, about 0.8 mm). The metal plate may be anything in the case of a double-sided laminated material, but it is necessary to use a single-sided laminated material to the outside of the battery or a material that is resistant to the electrolyte when not laminated. Moreover, as a polymer material to be laminated, polyethylene (PE), polypropylene (PP), or the like can be used.

  In such a double-winding sealing between the outer can 70 and the sealing plate 80, the overlapping degree (polymerization rate) of the double-winding, that is, the folding part 83 and the container folding part 75 with respect to the length of the double-clamping part. By setting the ratio of the length of the overlapping portion to 70% or more, it is possible to sufficiently ensure the strength and airtightness that can withstand the increase in the internal pressure of the battery.

  In addition, electrode terminals 90 and 90 are caulked and joined to the through holes 76 and 76 of the outer can 70 from the outside of the battery, respectively. As shown in FIGS. 14A and 14B, the electrode terminal 90 includes a metal pedestal portion 91 having a through-hole 91a, a metal terminal portion 92 passed through the through-hole 91a, a terminal portion 92, and a pedestal portion 91. And an insulating portion 93 that insulates the

  The pedestal portion 91 has an elliptical shape slightly larger than the through hole 76 of the outer can 70, and the periphery thereof is bent inward so that it can be caulked and joined to the through hole folded portion 76a to form a pedestal folded portion 91b. When caulking and joining, as shown in FIG. 15A, the base folding portion 91b is attached so as to cover the through-hole folding portion 76a.

  The terminal portion 92 is a flat metal terminal having a size that does not contact the through hole 91a. The insulating part 93 is a donut-shaped insulating material having a through-hole 93a, and an insulating resin such as rubber can be used. A groove is formed on the outer periphery of the insulating portion 93, and the groove is fitted into the through hole 91 a of the pedestal portion 91. Further, the terminal portion 92 is inserted into the through hole 93a without a gap.

  Then, as shown in FIG. 15A, after the base folding portion 91b is arranged so as to cover the through-hole folding portion 76a, it is caulked and joined as shown in FIG. 15B (preferably, helix and caulking). The electrode terminal 90 is fixed from the outside of the outer can 70. In addition, it is possible to obtain higher airtightness by applying a sealing material (not shown) to the part to be crimped.

  In FIG. 15B, the length C is a length in which the vicinity of the tip of the through hole folding portion 76a and the vicinity of the tip of the base folding portion 91b overlap, and the length D is from the inside of the bent portion of the through hole folding portion 76a. It is the length to the inside of the bent part of the base folding part 91b. Here, by setting the overlapping degree (polymerization rate) of the crimped joints, that is, the ratio of the length C to the length D to 50% or more, the strength (pressure resistance) and airtightness that can withstand the increase in the internal pressure of the battery. Sex can be secured.

  As shown in FIG. 4, the electrode group 40 includes an outer can 70 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 inside. Further, as shown in FIG. 4, the current collector exposed portion 11 a (see FIG. 7) of the positive electrode 10 and the current collector exposed portion 21 a (see FIG. 9) of the negative electrode 20 are respectively connected to the electrode terminals via the current collector leads 5. 90 is electrically connected. The current collector lead 5 may be made of the same material as the current collector, but may be made of a different material.

  Since the electrode terminal 90 and the electrode group 40 are electrically connected after the outer can 70 and the electrode terminal 90 are caulked and joined, the electrode group 40 is taken out of the outer can 70 in consideration of connection workability. In this state, it is desirable to connect the current collecting lead 5.

  As shown in FIG. 13, 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. The sealing plate 80 seals the opening 73 over the entire circumference. In addition, it is possible to obtain higher airtightness by applying a sealing material (not shown) to the part to be crimped.

  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. Thereby, the electrode group 40 (laminated body 40a) is pressed in the stacking direction (depth direction of the outer can 70; Z direction) by the outer can 70 and the sealing plate 80 in a state of being accommodated in the outer container 60. The positive electrode 10 and the negative electrode 20 are in close contact with the separator 30 in between.

  Further, as shown in FIG. 13, the length U in the lateral direction (X direction) of the outer bottom surface 71 a that is outside the bottom surface portion 71 is the lateral direction (X direction) of the outer top surface 81 a that is outside the panel portion 81. Is slightly shorter than the length V. Similarly, the length of the outer bottom surface 71a in the vertical direction (Y direction) is slightly shorter than the length of the outer top surface 81a in the vertical direction (Y direction). Therefore, the concave portion formed by the outer top surface 71a and the outer bottom surface 71a have a shape that fits substantially. Therefore, since a plurality of lithium ion secondary batteries 100 can be stacked by being substantially fitted vertically, it can be used as an assembled battery. The depth of the recess formed by the panel part 81 and the chuck wall part 82 after sealing (the height of the chuck wall part 82) is preferably about 1 to 20 mm.

  When the outer can 70 and the sealing plate 80 are double-wrapped and sealed as shown in FIG. 13, whether the outer can 70 and the sealing plate 80 are electrically connected or insulated is a combination of the materials of the outer can 70 and the sealing plate 80. It is as follows when divided according to.

  First, the combination in which the outer can 70 and the sealing plate 80 are electrically connected is a metal plate that is not laminated as the sealing plate 80 when the single-sided laminated material laminated on the inner side of the battery is used for the outer can 70, or the inner side or the outer side of the battery. When a single-sided laminated material laminated on the side is used and a single-sided laminated material laminated on the outer side of the battery is used for the outer can 70, a non-laminated metal plate or a single-sided laminated material laminated on the outer side of the battery is used as the sealing plate 80. When a non-laminated metal plate is used for the outer can 70, a non-laminated metal plate or a single-sided laminated material laminated on the inside or outside of the battery is used as the sealing plate 80.

  On the other hand, the combination in which the outer can 70 and the sealing plate 80 are insulated is such that when a single-sided laminate material laminated on the battery inner side is used for the outer can 70, a double-sided laminate material is used as the sealing plate 80, and the outer can 70 has a battery. When a single-sided laminated material laminated on the outer side is used, a single-sided laminated material or a double-sided laminated material laminated on the battery inner side is used as the sealing plate 80, and when a double-sided laminated material is used for the outer can 70, the sealing plate 80 is laminated. If a metal plate that is not laminated or a single-sided laminate material or a double-sided laminate material laminated on the inside or outside of the battery is used, and a metal plate that is not laminated on the outer can 70 is used, a double-sided laminate material is used as the sealing plate 80 It is.

  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 89 (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 of the first embodiment, when the battery internal pressure rises during overcharge or in a high temperature state, a safety valve (in order to release 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. Further, instead of providing a safety valve, the pressure resistance of the sealing portion of the outer container 60 may be designed to be about the operating pressure of the safety valve, and the battery internal pressure may be released by opening the sealing portion when the battery internal pressure increases.

  Further, by caulking and joining the electrode terminal 90 from the outside of the battery, when the internal pressure of the battery rises, a force is applied to the caulking joining portion in a direction that weakens the joining, so that the joining strength should be designed appropriately. Thus, the electrode terminal 90 can also function as a safety valve. The bonding strength is determined by the material and thickness of the pedestal 91 of the outer can 70 and the electrode terminal 90, the polymerization rate of caulking bonding, and the like.

  When the electrode terminal 90 operates as a safety valve, that is, when the electrode terminal 90 is detached from the outer can 70 due to an increase in internal pressure, it is desirable that at least one end of the current collecting lead 5 (see FIG. 4) is disconnected. As a result, the power supply is stopped, so that safety is improved. In order to disconnect the current collecting lead 5 when the caulking joint of the electrode terminal 90 is released, it is preferable that the caulking joining is rapidly released when the internal pressure of the battery exceeds a predetermined value.

  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. Further, the unit cell preferably has a weight of 1 kg or more. Moreover, it is preferable to modularize by connecting the single cells in series in units of 8 cells. Furthermore, it is preferable to operate two modules in combination at an average of 48V or more. In addition, it is preferable to use electric power obtained by a solar cell or wind power generation, midnight electric power, or the like for charging.

  An example of the lithium ion secondary battery 100 according to the first embodiment will be described below together with its manufacturing method.

[Production of positive electrode]
First, the active material LiFePO ₄ (90 parts by weight), the conductive material acetylene black (5 parts by weight), the binder styrene butadiene rubber (3 parts by weight), and the thickener CMC (2 parts by weight). Then, water was added as appropriate and dispersed to prepare a positive electrode mixture slurry. Next, the positive electrode mixture slurry was uniformly applied to both surfaces of an aluminum current collector (positive electrode current collector) having a thickness of 20 μm and dried, and then compressed by a roll press to a thickness of 400 μm. Finally, the positive electrode (positive electrode plate) was produced by cutting into a desired size. The size of the positive electrode active material layer was 150 mm long and 300 mm wide, and the positive electrode (positive electrode current collector) was 150 mm long and 320 mm wide.

[Production of negative electrode]
After mixing natural graphite (98 parts by weight) as an active material, styrene butadiene rubber (1 part by weight) as a binder, and CMC (1 part by weight) as a thickener, water is appropriately added and dispersed. Thus, a negative electrode mixture slurry was prepared. Next, this negative electrode mixture slurry was uniformly applied on both sides of a copper current collector (negative electrode current collector) having a thickness of 16 μm and dried, and then compressed by a roll press to a thickness of 350 μm. Finally, the negative electrode (negative electrode plate) was produced by cutting into a desired size. The size of the negative electrode active material layer applied region was 154 mm long and 304 mm wide, and the size of the negative electrode (negative electrode current collector) was 154 mm long and 324 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) obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume ratio of 3: 7.

[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, 50 positive plates and 51 negative plates were used so that the negative plate was located outside the positive plate. Further, by using 102 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 160 mm in length and 310 mm in width so as to be larger than the size on which the active material layers of the positive electrode plate and the negative electrode plate were applied.

  As the outer container, an outer can and a sealing plate were formed by processing a steel plate having a thickness of about 0.8 mm plated with nickel. The inner diameter of the outer can was 180 mm in the bottom portion, 350 mm in the bottom portion, and 40 mm in depth. As the electrode terminals, a positive electrode terminal having a pedestal portion made of stainless steel and a terminal portion made of aluminum, and a negative electrode terminal having a pedestal portion made of stainless steel and a terminal portion made of copper were formed.

  Then, after the electrode terminal was folded and joined to the outer can, the electrode group and the electrode terminal were electrically connected via the current collecting lead 5, and the electrode group and the electrode terminal were accommodated in the outer can. Subsequently, a sealing plate was placed, and the battery was sealed by double winding. Moreover, it comprised so that a pressing force might be added to the electrode group to the lamination direction by attaching a sealing board. At this time, a pressing force was applied to the electrode group with the sealing plate so that the ratio of the pressing amount with respect to the thickness of the electrode group in the stacking direction was 10%. Specifically, the sealing plate was fixed at a position where it was pushed in by about 1 mm from a state where the electrode group and the sealing plate were in direct or indirect contact.

  Subsequently, a predetermined amount of nonaqueous electrolyte was injected under reduced pressure from a φ2 mm injection hole provided in advance on the sealing plate. After the liquid injection, a metal sphere having the same diameter as the liquid injection hole was placed in the liquid injection hole, and the liquid injection hole was sealed by resistance welding, whereby the lithium ion secondary battery 100 was obtained.

(Second Embodiment)
16 is an overall perspective view of the lithium ion secondary battery of the second embodiment of the present invention, FIG. 17A is a front view of the electrode terminal of the lithium ion secondary battery of the second embodiment of the present invention, FIG. 17B is a cross-sectional view taken along the line EE of FIG. 17A.

  The lithium ion secondary battery 200 of the second embodiment is different from the lithium ion secondary battery 100 of the first embodiment in that both electrode terminals are provided on the same side wall portion of the outer can and the arrangement of the accompanying members. Unlike other configurations, the configuration is the same as that of the lithium ion secondary battery 100 of the first embodiment.

  The only difference between the outer can 270 and the outer can 70 of the first embodiment is the position and size of the through hole 276. Only one through hole 276 is provided in the side wall portion 272 parallel to the Y direction. The through hole 276 has an elliptical shape as shown in FIG. 16, for example, and the periphery thereof is bent outward to the extent that it can be crimped to the electrode terminal 290 to form a through hole folded portion (not shown).

  The electrode terminals 290 are caulked and joined to the through holes 276 of the outer can 270 from the outside of the battery. As shown in FIGS. 17A and 17B, the electrode terminal 290 includes a metal pedestal portion 291 having through holes 291a and 291b, and metal terminal portions 292 and 292 respectively passed through the through holes 291a and 291b. An insulating portion 293 that insulates the terminal portion 292 and the pedestal portion 291 is provided.

  The pedestal portion 291 has an elliptical shape slightly larger than the through hole 276 of the outer can 270, and the periphery thereof is bent inward to the extent that it can be crimped to the through hole folded portion 276a to form a pedestal folded portion 291b. When caulking and joining, the pedestal folded portion 291b is attached so as to cover the through hole folded portion.

  The terminal portion 292 is a flat metal terminal having a size that does not contact the through hole 291a. The insulating portion 293 is an insulating material having two through holes 293a and 293b, and an insulating resin such as rubber can be used. A groove is formed on the outer periphery of the insulating portion 293, and the groove is fitted in the through hole 291 a of the pedestal portion 291. In addition, terminal portions 292 are inserted into the through holes 293a and 293b without any gaps.

  Then, in accordance with FIG. 15A, the base folded portion 291b is arranged so as to cover the through-hole folded portion 276a, and then caulked and joined in accordance with FIG. The terminal 290 is fixed from the outside of the outer can 270. In addition, it is possible to obtain higher airtightness by applying a sealing material (not shown) to the part to be crimped.

  Moreover, in the lithium ion secondary battery 200 of 2nd Embodiment, it can connect with a short current collection lead by arranging the collector exposed part of a positive electrode and a negative electrode in the same side as the terminal part 290 in an electrode group. In the above description, the pedestal portion 291 of the electrode terminal 290 is single, but two electrode terminals 90 of the first embodiment may be arranged.

  Thus, the secondary battery of this invention can be utilized also for the use which takes out an electrode terminal from the same side surface.

(Third embodiment)
FIG. 18 is an overall perspective view of the lithium ion secondary battery according to the third embodiment of the present invention.

  Unlike the lithium ion secondary battery 100 of the first embodiment, the lithium ion secondary battery 300 of the third embodiment differs from the lithium ion secondary battery 100 of the first embodiment in that both electrode terminals are provided on the sealing plate and the arrangement of members accompanying the electrode terminals. Since other configurations including the configuration of 90 are the same as those of the lithium ion secondary battery 100 of the first embodiment, different points will be described in detail below.

  The sealing plate 380 is different from the sealing plate 80 of the first embodiment in that it has two through holes 386 and 386. It is preferable to provide the through holes 386 and 386 near the current collector exposed portion of the electrode group because the current collecting lead can be shortened. FIG. 18 shows a case where the electrode group 40 of the first embodiment is used, and the through holes 386 and 386 are provided near the end portion of the sealing plate 380 in the X direction.

  Since the electrode terminal 90 of the first embodiment is used as the electrode terminal, the through hole 386 has an elliptical shape as shown in FIG. 18, for example, and its periphery is bent outward to the extent that it can be caulked and joined to the electrode terminal 90. A hole folding portion (not shown) is formed.

  The electrode terminals 90 and 90 are caulked and joined to the through holes 386 and 386 of the sealing plate 380 from the outside of the battery, respectively.

  Then, after the base folded portion 91b is arranged so as to cover the through-hole folded portion according to FIG. 15A, it is caulked and joined in accordance with FIG. 90 is fixed from the outside of the sealing plate 380. In addition, it is possible to obtain higher airtightness by applying a sealing material (not shown) to the part to be crimped.

  In addition, although the two electrode terminals 90 of 1st Embodiment were used in the above, you may use the electrode terminal 290 of 2nd Embodiment.

  Thus, the secondary battery of this invention can be utilized also for the use which takes out an electrode terminal from an upper surface (sealing board).

(Other embodiments of electrode terminal)
19A is a front view of another electrode terminal of the lithium ion secondary battery of the present invention, and FIG. 19B is a cross-sectional view taken along line FF of FIG. 19A.

  As shown in FIGS. 19A and 19B, the electrode terminal 490 includes a metal pedestal portion 491 and a metal terminal portion 492 integrally formed so as to protrude from the front and back of the pedestal portion 491. Therefore, the base part 491 and the terminal part 492 are electrically connected. The electrode terminal 490 can be used in place of the electrode terminals of the first to third embodiments by appropriately using a laminate material for the outer can and the sealing plate.

  For example, when this electrode terminal 490 is connected to the outer can 70 of the first embodiment, the pedestal portion 491 has an elliptical shape slightly larger than the through hole 76 of the outer can 70, and the periphery thereof is caulked and joined to the through hole folded portion 76 a. A base folding portion 491b is formed by being bent inward as much as possible.

  Then, according to FIG. 15A, after the pedestal folded portion 491b is arranged so as to cover the through-hole folded portion 76a, it is caulked and joined so as to conform to FIG. The electrode terminal 490 is fixed from the outside of the outer can 70. In addition, it is possible to obtain higher airtightness by applying a sealing material (not shown) to the part to be crimped.

  Since the electrode terminal 490 is a metal integrally molded product and can be manufactured at a lower cost than the electrode terminal 90 of the first embodiment, the cost can be reduced when it is used when the pedestal portion and the terminal portion may be conductive.

(Still another embodiment of electrode terminal)
20A is a front view of still another electrode terminal of the lithium ion secondary battery of the present invention, and FIG. 20B is a cross-sectional view taken along the line GG of FIG. 20A.

  As shown in FIGS. 20A and 20B, the electrode terminal 590 includes a metal pedestal portion 591 having a through hole 591a, a metal terminal portion 592 passed through the through hole 591a, a terminal portion 592, and a pedestal portion 591. And an insulating portion 593 for insulating the. This electrode terminal 590 can be used in place of the electrode terminal of the first to third embodiments.

  When this electrode terminal 590 is connected to the outer can, the pedestal portion 591 has a circular shape slightly larger than the through-hole of the outer can, and the periphery thereof is bent inward so that it can be caulked and joined to the through-hole folded portion of the outer can. Thus, a base folding portion 591b is formed.

  The terminal portion 592 is a cylindrical metal terminal having a size that does not contact the through hole 591a. The insulating portion 593 is a donut-shaped insulating material having a through hole 593a, and an insulating resin such as rubber can be used. A groove is formed on the outer periphery of the insulating portion 593, and the groove is fitted into the through hole 591a of the pedestal portion 591. In addition, the terminal portion 592 is inserted in the through hole 593a without any gap.

  Then, in accordance with FIG. 15A, the pedestal folded portion 591b is disposed so as to cover the through hole folded portion of the outer can, and then caulked and joined in accordance with FIG. Thus, the electrode terminal 590 is fixed from the outside of the outer can. In addition, it is possible to obtain higher airtightness by applying a sealing material (not shown) to the part to be crimped.

  In this manner, the electrode terminal 590 is easily caulked by making the pedestal portion 591 circular. Note that the electrode terminal 590 may be integrally formed of metal like the electrode terminal 490 shown in FIGS. 19A and 19B so that the pedestal portion and the terminal portion are electrically connected.

(Other mounting forms before caulking and joining of electrode terminals)
FIG. 21 is a cross-sectional view of a state in which the electrode terminal before caulking is attached to the exterior container. FIG. 21 is a view in which the folding angle of the base folding portion 91b of the electrode terminal 90 and the through hole folding portion 76a of the outer can 70 is changed in FIG. 15A.

  The angle after the folding of the pedestal folded portion 91b of the electrode terminal 90 and the through hole folded portion 76a of the outer can 70 is made tighter than the state of FIG. It becomes difficult to come off until it is caulked after being attached to it, and it becomes easy to work. Further, since the amount of caulking is reduced, it becomes easy to caulk. FIG. 21 shows the first embodiment as an example, but the present invention can be similarly applied to the second and third embodiments.

  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 each of the embodiments described above, 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 thereto, and for example, the present invention is applied to a wound lithium ion secondary battery. The invention may be applied.

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

  In each of the above embodiments, an example in which the active material layer is formed on both surfaces of the current collector has been described. However, the present invention is not limited to this, and the active material layer may be formed only on one surface of the current collector. Good. 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, you may disperse | swell the swelling resin which has swelling property with respect to a non-aqueous electrolyte in the active material layer of an electrode. Examples of the swelling resin include nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVdF), polyvinyl alcohol (PVA), polyethylene oxide (PEO), propylene oxide, polystyrene A resin comprising at least one selected from polymethyl methacrylate can be used.

  In each of the above embodiments, an example in which a non-aqueous electrolyte is used as the electrolyte of the secondary battery has been shown. However, the present invention is not limited to this, and other than the non-aqueous electrolyte, such as a gel electrolyte, a polymer solid An electrolyte, an inorganic solid electrolyte, a molten salt, or the like may be used as the electrolyte.

  In each of the above embodiments, the example in which the opening of the outer can is double-wrapped with a sealing plate is shown. However, the present invention is not limited to this, and the sealing method for the outer can is double-wrapped. Other methods may be used. For example, the outer can may be sealed by welding the sealing plate to the outer can.

  In each of the above embodiments, the negative electrode (negative electrode active material layer) is configured to be larger than the positive electrode (positive electrode active material layer). However, the present invention is not limited to this, and the positive electrode ( The positive electrode active material layer) and the negative electrode (negative electrode active material layer) may be configured to have the same size, and the positive electrode (positive electrode active material layer) is larger than the negative electrode (negative electrode active material layer). You may comprise as follows.

  In each of the above embodiments, an example in which the current collector exposed portion is formed at one end of the current collector has been described. However, the present invention is not limited thereto, and the current collector exposed portion may be, for example, a current collector. It may be formed at both ends.

  Examples corresponding to the respective embodiments will be described below. Examples 1 to 13 correspond to the first embodiment, Examples 14 to 18 correspond to the second embodiment, and Examples 19 to 20 correspond to the third embodiment.

Example 1
The lithium ion secondary battery of Example 1 corresponds to the first embodiment, and the electrode terminals of the negative electrode and the positive electrode are the metal integrated terminals shown in FIGS. 19A and 19B (the positive electrode is aluminum and the negative electrode is copper), and the outer can The sealing plate was a double-sided laminate in which PE (0.02 mm thickness) was laminated on both sides of SUS (0.8 mm thickness). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are insulated.

(Example 2)
The lithium ion secondary battery of Example 2 corresponds to the first embodiment, and the negative electrode terminal is made of copper and the metal integrated molding terminal shown in FIGS. 19A and 19B and the positive electrode terminal is shown in FIGS. 14A and 14B. The insulating terminal, the outer can, and the sealing plate shown in the above were made SUS (0.8 mm thickness). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 3)
The lithium ion secondary battery of Example 3 corresponds to the first embodiment, and the negative electrode terminal and the positive electrode terminal are the insulating terminals, the outer can, and the sealing plate shown in FIGS. 14A and 14B. ). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

Example 4
The lithium ion secondary battery of Example 4 corresponds to the first embodiment, and the negative electrode terminal is made of an insulating terminal shown in FIGS. 14A and 14B, and the positive electrode terminal is made of aluminum as shown in FIGS. 19A and 19B. The metal integrated molded terminal shown and the outer can were made of aluminum (1 mm thickness), and the sealing plate was made of Fe-Al (1 mm thickness). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 5)
The lithium ion secondary battery of Example 5 corresponds to the first embodiment, the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, the outer can is aluminum (1 mm thick), and the sealing plate is Fe-Al (1 mm thickness) was used. Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 6)
The lithium ion secondary battery of Example 6 corresponds to the first embodiment, the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, the outer can is SUS (0.8 mm thickness), the sealing The plate was Fe-Ni (0.8 mm thick). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 7)
The lithium ion secondary battery of Example 7 corresponds to the first embodiment, the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, the outer can is Fe-Al (1 mm thickness), and the sealing The plate was aluminum (1 mm thickness). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 8)
The lithium ion secondary battery of Example 8 corresponds to the first embodiment. The negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, the outer can is aluminum (1 mm thick), and the sealing plate is A single-sided laminated material in which PE (0.05 mm thick) was laminated on the battery inner side of aluminum (1 mm thick) was used. Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

Example 9
The lithium ion secondary battery of Example 9 corresponds to the first embodiment. The negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, and the outer can is made of iron (0.8 mm thickness). A double-sided laminated material obtained by laminating PE (0.03 mm thickness) on the surface and aluminum (0.8 mm thickness) as the sealing plate. Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are insulated.

(Example 10)
The lithium ion secondary battery of Example 10 corresponds to the first embodiment, the negative and positive electrode terminals are the insulating terminals shown in FIGS. 14A and 14B, and the outer can is an iron (0.8 mm thick) battery. A single-sided laminated material in which PE (0.02 mm thickness) was laminated on the inner side, and a double-sided laminated material in which PE (0.02 mm thickness) was laminated on both sides of iron (0.8 mm thickness) as the sealing plate. Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are insulated.

(Example 11)
The lithium ion secondary battery of Example 11 corresponds to the first embodiment, the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, the outer can and the sealing plate are Fe—Ni (1 mm thick). ) Was laminated on the outside of the battery with PE (0.02 mm thickness). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 12)
The lithium ion secondary battery of Example 12 corresponds to the first embodiment, the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, the outer can and the sealing plate are iron (0.8 mm thick). ) Was laminated on the inside of the battery with PE (0.03 m thickness). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 13)
The lithium ion secondary battery of Example 13 corresponds to the first embodiment. The negative and positive electrode terminals are the insulating terminals shown in FIGS. 14A and 14B, and the outer can is made of aluminum (0.8 mm thick). A PE (0.03 mm thick) double-sided laminate and a sealing plate made of Fe-Al (0.8 mm thick). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 14)
The lithium ion secondary battery of Example 14 corresponds to the second embodiment. The negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 17A and 17B, the outer can and the sealing plate are Fe—Ni (0. 8 mm thick). In addition, one example of the first embodiment is followed except that in the electrode group, the current collector exposed portions of the positive electrode and the negative electrode are aligned on the same side as the terminal portion. Therefore, the outer can and the sealing body are electrically connected.

(Example 15)
The lithium ion secondary battery of Example 15 corresponds to the second embodiment. The negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 17A and 17B, the outer can and the sealing plate are Fe-Al (1 mm thick). ). In addition, one example of the first embodiment is followed except that in the electrode group, the current collector exposed portions of the positive electrode and the negative electrode are aligned on the same side as the terminal portion. Therefore, the outer can and the sealing body are electrically connected.

(Example 16)
The lithium ion secondary battery of Example 16 corresponds to the second embodiment, the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 17A and 17B, the outer can and the sealing plate are iron (0.8 mm thick). ) Was laminated on both sides with PE (0.02 mm thickness). In addition, one example of the first embodiment is followed except that in the electrode group, the current collector exposed portions of the positive electrode and the negative electrode are aligned on the same side as the terminal portion. Therefore, the outer can and the sealing body are insulated.

(Example 17)
The lithium ion secondary battery of Example 17 corresponds to the second embodiment. The negative and positive electrode terminals are the insulating terminals shown in FIGS. 17A and 17B, and the outer can is Fe-Ni (0.8 mm thick). The sealing plate was made of aluminum (0.8 mm thickness). In addition, one example of the first embodiment is followed except that in the electrode group, the current collector exposed portions of the positive electrode and the negative electrode are aligned on the same side as the terminal portion. Therefore, the outer can and the sealing body are electrically connected.

(Example 18)
The lithium ion secondary battery of Example 18 corresponds to the second embodiment, the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 17A and 17B, the outer can and the sealing plate are aluminum (1 mm thick). did. In addition, one example of the first embodiment is followed except that in the electrode group, the current collector exposed portions of the positive electrode and the negative electrode are aligned on the same side as the terminal portion. Therefore, the outer can and the sealing body are electrically connected.

(Example 19)
The lithium ion secondary battery of Example 19 corresponds to the third embodiment, and the negative electrode terminal and the positive electrode terminal are the insulating terminals shown in FIGS. 14A and 14B, the outer can, and the sealing plate are Fe—Ni (0. 8 mm thick). Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are electrically connected.

(Example 20)
The lithium ion secondary battery of Example 20 corresponds to the third embodiment, and the negative electrode terminal and the positive electrode terminal are made of the insulating terminal shown in FIGS. 14A and 14B, the outer can, and the sealing plate made of aluminum (1 mm thick). A double-sided laminate in which PE (0.02 mm thick) was laminated on both sides was used. Other configurations follow one example of the first embodiment. Therefore, the outer can and the sealing body are insulated.

(Evaluation results of Examples 1 to 20)
The lithium ion secondary battery of Examples 1-20 was produced and evaluated as follows. A constant current and constant voltage charge was performed at a charge voltage of 3.5 V for 5 hours, and then a low current discharge up to 2.5 V was performed to measure a battery capacity (initial battery capacity). And the cycle test was done on said charging / discharging conditions in the environment whose ambient temperature is 45 degreeC. As a result, in all the examples, the capacity retention with respect to the initial discharge capacity was 93% or more even after 200 cycles. There was no liquid leakage from the electrode terminals or the like.

  Next, various lithium ion secondary batteries of Example 3 were produced by changing the overlapping degree (polymerization rate) of the caulking joint between the outer can and the electrode terminal, and the hermeticity was evaluated. In this evaluation, a hole was formed in the bottom of the outer can so that pressure could be applied to the inside of the battery, and no electrolyte solution was added. These batteries were held in water, the inside of the outer can was gradually pressurized, and airtightness was evaluated by examining the leakage of bubbles. As a result, in the lithium ion secondary battery having a polymerization rate of 50% or more, even if the pressure in the outer can exceeds 1 MPa, air bubbles are not observed from the caulked joint portion between the outer can and the electrode terminal, and the airtightness is maintained. It was.

  Next, the airtightness of the lithium ion secondary battery of Example 5 and the lithium ion secondary battery in which the pedestal portion of the electrode terminal of Example 5 was changed to aluminum were evaluated. As a result, in both lithium ion secondary batteries, even if the pressure in the outer can exceeded 1 MPa, no air bubbles were observed from the caulked joint portion between the outer can and the electrode terminal, and the airtightness was maintained. And in both lithium ion secondary batteries, the electrode terminal came off at a stretch when the pressure in the outer can exceeded 5 MPa. Therefore, it can be said that the electrode terminal functions as a safety valve.

  As mentioned above, it can be said that the lithium ion secondary battery of Examples 1-20 satisfy | fills the fixed performance calculated | required by a secondary battery.

5 Current collector lead 10 Positive electrode (electrode)
DESCRIPTION OF SYMBOLS 11 Positive electrode collector 11a Current collector exposed part 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 Laminated body 60 Exterior container 70, 370 Exterior can (storage container)
71 Bottom surface portion 71a Outer bottom surface 72 Side wall portion 73 Opening portion 75 Container return portion 76, 276 Through hole 80 Sealing plate (sealing body)
81 Panel part 81a Outer top surface 82 Chuck wall part 83 Folding part 84 Injection hole 90, 290, 490, 590 Electrode terminal 91, 291, 491, 591 Pedestal part 91a, 291a, 591a Through hole 91b, 291b, 491b, 591b Base folding part 92, 292, 492, 592 Terminal part 93, 293, 593 Insulating part 93a, 293a, 293b, 593a Through hole 100, 200, 300 Lithium ion secondary battery (secondary battery)
386 Through hole

Claims (15)

An electrode group including a positive electrode and a negative electrode;
An exterior container including a storage container that stores the electrode group and a sealing body that seals an opening of the storage container;
A pair of electrode terminals that are caulked and joined to the exterior container from the outside of the exterior container;
A secondary battery comprising: an electrolyte solution filled in the outer container.   The secondary battery according to claim 1, wherein the pair of electrode terminals are provided in the storage container of the outer container.   The secondary battery according to claim 2, wherein the pair of electrode terminals are provided on opposite side walls of the storage container.   The secondary battery according to claim 2, wherein the pair of electrode terminals are provided on the same side wall portion of the storage container.   The secondary battery according to claim 1, wherein the pair of electrode terminals are provided on the sealing body of the outer container. At least one of the pair of electrode terminals includes a metal base portion having a through hole, a metal terminal portion passed through the through hole, and an insulating portion that insulates the terminal portion and the base portion. Have
The secondary battery according to claim 1, wherein the pedestal is caulked and joined to the exterior container. At least one of the pair of electrode terminals has a metal pedestal portion and a metal terminal portion integrally formed so as to protrude from the front and back of the pedestal portion,
The secondary battery according to claim 1, wherein the pedestal is caulked and joined to the exterior container. The storage container is made of a double-sided laminate in which an insulating resin is laminated on both sides of a metal plate,
The pair of electrode terminals includes a metal pedestal portion and a metal terminal portion integrally formed so as to protrude from the front and back of the pedestal portion, and the pedestal portion is caulked and joined to the exterior container. The secondary battery according to claim 2. The storage container is made of a single-sided laminated material in which an insulating resin is laminated on one side of a metal plate,
One of the electrode terminals insulates a metal first pedestal portion having a through hole, a metal first terminal portion passed through the through hole, and the first terminal portion and the first pedestal portion. And the first pedestal portion is caulked and joined,
The other electrode terminal has a metal second pedestal portion and a metal second terminal portion integrally formed so as to protrude from the front and back of the second pedestal portion, and the second pedestal portion is The secondary battery according to claim 2, wherein the secondary battery is caulked and joined to the outer container.   The secondary battery according to claim 8 or 9, wherein a thickness of the metal plate is 0.5 mm or more and 2 mm or less. The storage container is made of a metal plate,
The pair of electrode terminals includes a metal pedestal portion having a through hole, a metal terminal portion passed through the through hole, and an insulating portion that insulates the terminal portion and the pedestal portion, The secondary battery according to claim 2, wherein the pedestal portion is caulked and joined to the exterior container.   The secondary battery according to any one of claims 1 to 10, wherein the caulking is a crease caulking.   The secondary battery according to claim 12, wherein an overlap at the time of the folding is 50% or more.   The secondary battery according to claim 1, wherein the storage container and the sealing body are double-tightened and sealed.   The secondary battery according to claim 14, wherein an overlap when performing the double winding sealing is 70% or more.

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