JP2011071044A - Bipolar secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bipolar secondary battery capable of further improving the sealing characteristics. <P>SOLUTION: In the bipolar secondary battery 100, a plurality of bipolar electrodes 110, in which a positive-electrode active material layer 113 is formed on one face of a current collector 111 and a negative-electrode active material layer 112 is formed on the other face are laminated in a plurality numbers via a separator 140. The bipolar secondary battery has a first sealing member 122, arranged on one face by surrounding the negative electrode active material layer and a second sealing member 120, arranged on the other face by surrounding the negative electrode active material layer. Moreover, the bipolar secondary battery has a first protruding part 123, installed at the first sealing member and protruded from the end part of the current collector and a second protrusion part 121 installed at the second sealing member and protruded from the end part of the current collector, and then the bipolar secondary battery has a folded part 130 in which the first protrusion part and the second protrusion part are folded toward the end part of the current collector. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bipolar secondary battery.

  A bipolar secondary battery generally has a configuration in which a plurality of bipolar electrodes, each having a positive electrode active material layer formed on one surface of a current collector and a negative electrode active material layer formed on the other surface, are stacked via a separator. Have. For example, as described in Patent Document 1, a seal member for preventing leakage of the electrolyte is provided near the end of the current collector.

JP 2007-122881 A

  By the way, the seal member is partly provided so as to protrude from the end portion of the current collector, and is disposed on the one surface side of the current collector and the other surface side of the current collector. A gap is generated in the portion that protrudes from the end of the current collector with the seal member. For this reason, for example, when a bipolar electrode, a separator, and the like are sealed with an exterior material, a force is applied, and the seal members protruding from the end portions of the current collector are deformed so as to sandwich the gap.

  The present inventors paid attention to this, and tried to further improve the sealing performance by suppressing the deformation of the sealing member.

  In order to achieve the above object, a bipolar secondary battery of the present invention comprises a bipolar electrode in which a positive electrode active material layer is formed on one surface of a current collector and a negative electrode active material layer is formed on the other surface. It has the structure laminated | stacked via this. The bipolar secondary battery includes a first seal member disposed on one surface surrounding the positive electrode active material layer, and a second seal member disposed on the other surface surrounding the negative electrode active material layer. Have. The bipolar secondary battery includes a first protruding portion provided on the first seal member and protruding from the end portion of the current collector, and a second protruding portion provided on the second seal member and extending from the end portion of the current collector. And a protruding portion. The bipolar secondary battery has a folded portion formed by folding the first protruding portion and the second protruding portion toward the end of the current collector.

  Since the bipolar secondary battery of the present invention has a fold-in portion and suppresses deformation of the first seal member and the second seal member, the sealing performance can be further improved.

It is a schematic perspective view which shows typically the outline | summary of a bipolar lithium ion secondary battery. It is sectional drawing which follows the 2-2 line of FIG. (A) is the partial expanded sectional schematic for demonstrating folding of the 1st sealing member and the 2nd sealing member, (B) is the partial expanded schematic sectional view of the electric power generation element of 1st Embodiment. (A) is the partial expanded sectional schematic for demonstrating folding of one separator, (B) is the partial expanded schematic sectional view of the electric power generation element of 2nd Embodiment. It is a partial expansion schematic sectional drawing of the electric power generation element of 3rd Embodiment. It is a partial expansion schematic sectional drawing of the electric power generation element of 4th Embodiment. (A) is the partial expanded sectional schematic for demonstrating folding of one separator and another separator, (B) is the partial expanded schematic sectional view of the electric power generation element of 5th Embodiment. It is a partial expansion schematic sectional drawing of the electric power generation element of 6th Embodiment. It is a partial expanded schematic sectional drawing of the electric power generation element of 7th Embodiment. It is a top view which shows the example of a sealing member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments described below, members having functions common to the respective embodiments are denoted by similar reference numerals, and redundant description is omitted.

<First Embodiment>
Referring to FIG. 1, the bipolar lithium ion secondary battery 100 of the first embodiment has a substantially rectangular and flat shape. And the positive electrode tab 104 and the negative electrode tab 106 for taking out electric power from the opposite side edge part are pulled out. The bipolar lithium ion secondary battery 100 includes a power generation element 102 that actually undergoes a charge / discharge reaction and an exterior material 108 that seals the power generation element 102.

  As the exterior material 108, a laminate film, polyethylene, polypropylene, polycarbonate, or the like can be suitably used. The laminate film is obtained by coating a metal foil made of a metal (including an alloy) such as aluminum, stainless steel, nickel, or copper with an insulating synthetic resin film such as a polypropylene film.

  As shown in FIG. 2, the power generation element 102 has a positive electrode active material layer 113 electrically connected to one surface of the current collector 111 and a negative electrode electrically connected to the other surface of the current collector 111. It has a plurality of bipolar electrodes 110 on which an active material layer 112 is formed.

  The power generation element 102 has a configuration in which a plurality of bipolar electrodes 110 are stacked with a separator 140 interposed therebetween. A positive electrode active material layer 113 of one bipolar electrode 110 and a negative electrode active material layer 112 of another bipolar electrode 110 adjacent to one bipolar electrode 110 face each other with a separator 140 interposed therebetween. In addition, the negative electrode active material layer 112 of one bipolar electrode 110 and the positive electrode active material layer 113 of another bipolar electrode 110 adjacent to the one bipolar electrode 110 face each other with a separator 140 interposed therebetween.

  The adjacent positive electrode active material layer 113, separator 140, and negative electrode active material layer 112 constitute one single cell layer. Therefore, it can be said that the bipolar lithium ion secondary battery 100 has a configuration in which single battery layers are stacked.

  In the outermost layer current collectors 105 and 107 located on the outermost side in the stacking direction, the positive electrode active material layer 113 or the negative electrode active material layer 112 is formed only on one side. However, the positive electrode active material layer 113 or the negative electrode active material layer 112 may be formed on both surfaces. The bipolar lithium ion secondary battery 100 has current collector plates 101 and 103 adjacent to the outermost layer current collectors 105 and 107, which extend to the outside of the exterior material 108 to form the positive electrode tab 104 or the negative electrode tab 106. To do.

  As shown in FIG. 3, the bipolar lithium ion secondary battery 100 includes a first seal disposed on one surface of the current collector 111 so as to surround the positive electrode active material layer 113 in order to prevent leakage of the electrolytic solution. A member 122 and a second seal member 120 disposed on the other surface of the current collector 111 so as to surround the negative electrode active material layer 112 are included. The first seal member 122 and the second seal member 120 insulate the current collectors from each other.

  The material of the current collector 111 is not particularly limited, but specific examples include, for example, iron, chromium, nickel, manganese, titanium, molybdenum, vanadium, niobium, aluminum, copper, silver, gold, platinum, and carbon. Preferred is at least one current collector material selected from the group, more preferably at least one material selected from the group consisting of aluminum, titanium, copper, nickel, silver, or stainless steel (SUS). These may be used in a single layer structure (for example, in the form of a foil), may be used in a multilayer structure composed of different kinds of layers, or clad materials (for example, nickel and the like) coated with these layers. Aluminum clad material, copper and aluminum clad material) may also be used. Alternatively, a plating material of a combination of these current collector materials can be preferably used. Further, the current collector 111 may be a current collector material in which the surface of a metal (excluding aluminum) as the current collector material is covered with aluminum as another current collector material. In some cases, a current collector 111 in which two or more metal foils as the current collector material are bonded together may be used. The above materials are excellent in corrosion resistance, conductivity, workability, and the like.

  The current collector 111 may include a conductive resin. Preferably, the current collector 111 is made of a conductive resin layer. The resin layer has conductivity, essentially contains a resin, and plays a role of the current collector 111.

  In order for the resin layer to have conductivity, a specific form includes a form in which the polymer material constituting the resin is a conductive polymer. The conductive polymer is selected from materials that are conductive and have no conductivity with respect to ions used as charge transfer media. These conductive polymers are considered to be conductive because the conjugated polyene system forms an energy band. As a typical example, a polyene-based conductive polymer that has been put into practical use in an electrolytic capacitor or the like can be used.

  In addition, in order for the resin layer to have conductivity, a specific form includes a form in which the resin layer includes a resin and a conductive filler (conductive material). The conductive filler (conductive material) is selected from materials having conductivity. Preferably, from the viewpoint of suppressing ion permeation in the resin layer having conductivity, it is desirable to use a material that does not have conductivity with respect to ions used as the charge transfer medium. Specific examples include, but are not limited to, aluminum materials, stainless steel (SUS) materials, carbon materials such as graphite and carbon black, silver materials, gold materials, copper materials, and titanium materials.

  The positive electrode active material layer 113 includes a positive electrode active material. In addition, a conductive auxiliary agent, a binder, and the like can be included. Examples of the positive electrode active material include a lithium-transition metal oxide, a lithium-transition metal phosphate compound, and a lithium transition metal sulfate compound.

  The negative electrode active material layer 112 includes a negative electrode active material. In addition, a conductive auxiliary agent, a binder, and the like can be included. Examples of the negative electrode active material include carbon materials, lithium-transition metal compounds, metal materials, and lithium-metal alloy materials.

  The separator 140 is not particularly limited, and a known separator can be used. Examples thereof include polyolefin resins such as a microporous polyethylene film, a microporous polypropylene film, and a microporous ethylene-propylene copolymer film, and porous films or nonwoven fabrics such as aramid, polyimide, and cellulose, and laminates thereof.

  The separator 140 holds the electrolyte. The electrolyte is, for example, a polymer gel electrolyte (gel polymer electrolyte) or a liquid electrolyte.

  Here, the gel electrolyte (polymer gel electrolyte) refers to an electrolyte solution held in a matrix polymer (host polymer). Examples of the matrix polymer include a polymer having polyethylene oxide in the main chain or side chain (PEO), a polymer having polypropylene oxide in the main chain or side chain (PPO), polyethylene glycol (PEG), polyacrylonitrile (PAN), poly Methacrylic acid ester, polyvinylidene fluoride (PVdF), copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN), poly (methyl acrylate) (PMA), poly (methyl methacrylate) (PMMA) ) And the like. In addition, mixtures of the above-described polymers, modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers, and the like can also be used. Among these, it is desirable to use PEO, PPO and their copolymers, PVdF, PVdF-HFP.

Moreover, as an electrolytic solution (plasticizer), it is possible to use an electrolytic solution usually used for a lithium ion battery. And such electrolyte, an electrolyte salt are those dissolved in a solvent, as the electrolyte _{salt, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiSbF 6, LiAlCl 4, Li 2 B 10 Cl 10, _{LiI, LiBr, LiCl, LiAlCl,} LiHF 2, inorganic acid anion salts such as _{LiSCN, LiCF 3 SO 3, Li} (CF 3 SO 2) 2 N, LiBOB ( lithium bis oxide borate), LiBETI (lithium bis (perfluoro And an organic acid anion salt such as Li (C ₂ F ₅ SO ₂ ) ₂ N). These electrolyte salts may be used alone or in the form of a mixture of two or more. As the solvent, ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethoxyethane. , Sulfolane, acetonitrile and the like. Such an electrolytic solution can be used as a liquid electrolyte.

  The first seal member 122 and the second seal member 120 can use, for example, a rubber-based resin that is in close contact with the current collector 111 by being deformed under pressure. In addition, the first seal member 122 and the second seal member 120 preferably use a heat-sealable resin such as an olefin resin that is in close contact with the current collector 111 by heat-pressing and heat-sealing. can do.

  The rubber resin is not particularly limited, but is preferably a rubber resin selected from the group consisting of silicon rubber, fluorine rubber, olefin rubber, and nitrile rubber. These rubber-based resins are excellent in sealing properties, alkali resistance, chemical resistance, durability / weather resistance, heat resistance, etc., and should be maintained for a long period of time without degrading their excellent performance and quality even in the use environment. Can do.

  The resin that can be heat-sealed is not particularly limited as long as it can exhibit an excellent sealing effect as a seal portion under any usage environment of the power generation element 102. A resin selected from the group consisting of silicon, epoxy, urethane, polybutadiene, olefinic resins (polypropylene, polyethylene, etc.), and paraffin wax is preferable. These heat-sealable resins are excellent in sealing properties, alkali resistance, chemical resistance, durability / weather resistance, heat resistance, etc., and even in the usage environment, these excellent performance and quality are not deteriorated for a long time. Can be maintained.

  The bipolar lithium ion secondary battery 100 includes a first protruding portion 123 provided on the first seal member 122 and protruding from an end of the current collector 111, and a second seal member 120 provided on the current collector 111. And a second protruding portion 121 protruding from the end portion.

  The bipolar lithium ion secondary battery 100 has a folded portion 130 formed by folding the first protruding portion 123 and the second protruding portion 121 toward the end of the current collector 111. The sum of the thickness of the first seal member 122 and the thickness of the second seal member 120 is preferably equal to or greater than the thickness of the current collector 111. Preferably, the sum of the thickness of the first seal member 122 and the thickness of the second seal member 120 is equal to the thickness of the current collector 111 + the thickness of the separator 140 × 0.5 or less.

  The first seal member 122 disposed on one bipolar electrode 110 and the second seal member 120 disposed on the other bipolar electrode 110 overlap each other to form a positive electrode active material layer 113, a separator 140, and The negative electrode active material layer 112 is surrounded and sealed. In addition, the second seal member 120 disposed on one bipolar electrode 110 and the first seal member 122 disposed on another bipolar electrode 110 overlap each other, and the positive electrode active material layer 113 and the separator are overlapped with each other. 140 and the negative electrode active material layer 112 are enclosed and sealed. The bipolar lithium ion secondary battery 100 has a first protruding portion 123 and a second protruding portion 121 along the entire outer periphery of the current collector 111, and is folded along the entire outer periphery of the current collector 111. A unit 130 is provided.

  A plurality of bipolar lithium ion secondary batteries 100 can be connected in series or in parallel to form a battery module, and a plurality of battery modules can be further connected in series or in parallel to form a battery pack. In the battery module, a plurality of bipolar lithium ion secondary batteries 100 are stacked and accommodated in a module case, and the bipolar lithium ion secondary batteries 100 are connected in parallel.

  The produced battery modules are connected to each other using an electrical connection member such as a bus bar, and are stacked in a plurality of stages.

  The effect of the first embodiment will be described.

  Unlike this embodiment, when the 1st protrusion part 123 and the 2nd protrusion part 121 are extended without being folded in, a clearance gap will arise between them. For example, when sealing with the exterior material 108, a force is applied, and the first seal member 122 and the second seal member 120 are deformed so as to sandwich the gap. In particular, the first seal member 122 and the second seal member 120 positioned on the outer side in the stacking direction are greatly deformed as compared with the first seal member 122 and the second seal member 120 positioned on the center side in the stacking direction. To do.

  On the other hand, the bipolar lithium ion secondary battery 100 has a folding portion 130 and suppresses deformation of the first seal member 122 and the second seal member 120, so that the sealing performance is improved, and thus the long-term reliability is improved. Can be planned.

  In the present embodiment, the sum of the thickness of the first seal member 122 and the thickness of the second seal member 120 is equal to or greater than the thickness of the current collector 111. That is, the thickness of the folding part 130 is equal to or greater than the gap. Accordingly, the surface pressure is easily applied and the sealing members are in close contact with each other, so that the sealing performance is excellent.

  Unlike the present embodiment, the folding portion 130 is provided only at a part of the outer periphery of the current collector 111. If the current collector 111 contains a resin, There exists a possibility that it melt | dissolves and it comes out to the outer side of a sealing member, and the micro short circuit of current collectors may arise. On the other hand, in this embodiment, since the folding part 130 is provided along the whole outer periphery of the electrical power collector 111, the above-mentioned micro short circuit of electrical power collectors can be suppressed and it is preferable.

  Further, in this embodiment, since the folded portion 130 is formed by folding the first protruding portion 123 and the second protruding portion 121, they are integrated and, for example, another member such as a spacer is disposed in the gap. Excellent seismic vibration resistance.

  By using a metal material as the material of the current collector 111, conductivity, heat resistance, and strength can be improved. Further, by using a conductive resin as the material of the current collector 111, the current collector 111 can be reduced in weight, and the output density per weight of the battery can be improved. In addition, by using a conductive resin as the material of the current collector 111, elution like a metal material can be suppressed and solvent resistance can be improved.

  When the positive electrode active material layer 113 contains a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound as a positive electrode active material, a battery having excellent capacity and output characteristics can be configured.

  When the negative electrode active material layer 112 includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material as a negative electrode active material, a battery having excellent capacity and output characteristics can be configured.

  Since the bipolar lithium ion secondary battery 100 includes a liquid electrolyte or a gel electrolyte and ions are transported more efficiently than an all-solid electrolyte that does not include an electrolytic solution, the ion conductivity can be improved and thus the output can be improved.

Second Embodiment
Referring to FIG. 4, the second embodiment is substantially the same as the first embodiment, but the folding portion 231 is different from the first embodiment, and the first seal member 222A and the second seal member 220A are different. Touch each other.

  In the second embodiment, the end of the separator 240 protrudes between the first seal member 222A and the second seal member 220 and between the first seal member 223 and the second seal member 220A. Yes. The folding portion 231 has a configuration in which the end of one separator 240 is folded between the first protruding portion 223 and the second protruding portion 221. The thickness of the separator 240 is preferably the same as the thickness of the current collector 211 or larger than the thickness of the current collector 211.

  The first seal member 222 and the second seal member 220A seal the separator 240 by heat sealing. The first seal member 222A and the second seal member 220 seal the separator 240 by heat sealing.

  The effect of 2nd Embodiment is described.

  The bipolar lithium ion secondary battery of the second embodiment has a folding part 231 and suppresses deformation of the first seal member 222 and the second seal member 220, so that the sealing performance is improved, and thus long-term reliability is achieved. Can be improved.

  In the present embodiment, the separator 240 has the same thickness as the current collector 211 or thicker than the current collector 211. That is, the thickness of the folding part 231 is equal to or greater than the gap between the first protruding part 223 and the second protruding part 221. Accordingly, the surface pressure is easily applied, and the seal members are in close contact with each other and the seal member and the separator 240 are in close contact with each other.

  In the present embodiment, since the end portion of the separator 240 protrudes from the seal member, it is possible to improve heat dissipation and consequently suppress deterioration of the electrolytic solution.

  Unlike the present embodiment, the folding portion 231 is provided only in a part of the outer periphery of the current collector 211. When the current collector 211 contains a resin, the current collector 211 is There exists a possibility that it melt | dissolves and it comes out to the outer side of a sealing member, and the micro short circuit of current collectors may arise. On the other hand, in this embodiment, since the folding part 231 is provided along the whole outer periphery of the electrical power collector 211, it can suppress the micro short circuit between the above electrical power collectors, and is preferable.

  By using a metal material as the material of the current collector 211, the conductivity, heat resistance, and strength can be improved. Further, by using a conductive resin as the material of the current collector 211, the current collector 211 can be reduced in weight, and the output density per weight of the battery can be improved. In addition, by using a conductive resin as the material of the current collector 211, elution like a metal material can be suppressed and solvent resistance can be improved.

  When the positive electrode active material layer 213 includes a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound as a positive electrode active material, a battery having excellent capacity and output characteristics can be configured.

  When the negative electrode active material layer 212 includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material as a negative electrode active material, a battery having excellent capacity and output characteristics can be configured.

  The bipolar lithium ion secondary battery according to the second embodiment includes a liquid electrolyte or a gel electrolyte, and ions are transported more efficiently than an all-solid electrolyte that does not include an electrolyte solution. Can be planned.

<Third Embodiment>
If it demonstrates in FIG. 5, 3rd Embodiment is substantially the same as 2nd Embodiment, However, The point which further has the spacer 332 arrange | positioned between the 1st protrusion part 323 and the 2nd protrusion part 321 is. Different from the second embodiment.

  The spacer 332 can be formed of, for example, a thermoplastic resin such as polypropylene or polyethylene, or a thermosetting resin such as epoxy. The spacer 332 preferably has a lower melting point than the first seal member 322 and the second seal member 320. The thickness of the spacer 332 is preferably the same as the thickness of the current collector 311 or thicker than the current collector 311.

  The effects of the third embodiment will be described.

  The bipolar lithium ion secondary battery of the third embodiment has a folding part 331 and a spacer 332, and suppresses deformation of the first seal member 322 and the second seal member 320, thereby improving the sealing performance. As a result, long-term reliability can be improved.

  In this embodiment, the separator 340 has the same thickness as the current collector 311 or thicker than the current collector 311, and the spacer 332 has the same thickness as the current collector 311, or It is thicker than the current collector 311. That is, the thickness of the folding part 331 and the thickness of the spacer 332 are greater than or equal to the gap. Accordingly, the surface pressure is easily applied, and the sealing member is excellent because the sealing member, the sealing member and the separator 340, and the sealing member and the spacer 332 are in close contact with each other.

  In the present embodiment, since the end portion of the separator 340 protrudes from the seal member, it is possible to improve heat dissipation and to suppress deterioration of the electrolytic solution.

  Unlike the present embodiment, when the folded portion 331 and the spacer 332 are provided only at a part of the outer periphery of the current collector 311, and the current collector 311 contains a resin, the current collector is collected when the seal member is heat-sealed. There is a possibility that the body 311 melts and comes out of the seal member, and a short circuit between the current collectors 311 occurs. On the other hand, in this embodiment, since the folding portion 331 and the spacer 332 are provided along the entire outer periphery of the current collector 311, the above-described minute short circuit between the current collectors 311 can be suppressed, which is preferable.

  By using a metal material as the material of the current collector 311, conductivity, heat resistance, and strength can be improved. Further, by using a conductive resin as a material for the current collector 311, the current collector 311 can be reduced in weight, and the output density per weight of the battery can be improved. In addition, by using a conductive resin as a material for the current collector 311, elution like a metal material can be suppressed and solvent resistance can be improved.

  When the positive electrode active material layer 313 contains a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound as a positive electrode active material, a battery having excellent capacity and output characteristics can be configured.

  When the negative electrode active material layer 312 includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material as a negative electrode active material, a battery having excellent capacity and output characteristics can be configured.

  The bipolar lithium ion secondary battery of the third embodiment includes a liquid electrolyte or a gel electrolyte, and ions are transported more efficiently than an all-solid electrolyte that does not include an electrolytic solution. Can be planned.

<Fourth embodiment>
As shown in FIG. 6, the fourth embodiment has a configuration combining the configuration of the first embodiment and the configuration of the second embodiment. That is, the bipolar lithium ion secondary battery of the fourth embodiment includes the folding part 430 having the same configuration as the folding part 130 of the first embodiment and the folding part 431 having the same configuration as the folding part 231 of the second embodiment. And have.

  The folding part 430 is provided in the first seal member 422 and protrudes from the end of the current collector 411. The folding part 430 is provided in the second seal member 420 and protrudes from the end of the current collector 411. 2 has a configuration in which the protruding portion 421 is folded toward the end of the current collector 411. The sum of the thickness of the first seal member 422 and the thickness of the second seal member 420 is preferably equal to or greater than the thickness of the current collector 411. Preferably, the sum of the thickness of the first seal member 422 and the thickness of the second seal member 420 is equal to the thickness of the current collector 411 + the thickness of the separator 440 × 0.5 or less.

  The folding part 431 has a configuration in which the end of the separator 440 is folded between the first protruding part 423 and the second protruding part 421. The thickness of the separator 440 is preferably the same as that of the current collector 411 or thicker than that of the current collector 411.

  The effect of 4th Embodiment is described.

  The bipolar lithium ion secondary battery has a folding part 430 and a folding part 431, and suppresses deformation of the first seal member 422 and the second seal member 420, so that the sealing performance is improved, and thus long-term reliability is achieved. Can be improved.

  In the present embodiment, the sum of the thickness of the first seal member 422 and the thickness of the second seal member 420 is equal to or greater than the thickness of the current collector 411. In addition, the thickness of the separator 440 is the same as that of the current collector 411 or thicker than that of the current collector 411. That is, the thickness of the folding part 430 and the folding part 431 is more than a clearance. Accordingly, the surface pressure is easily applied, and the seal members are in close contact with each other and between the seal member and the separator 440, so that the sealing performance is excellent.

  In the present embodiment, since the end portion of the separator 440 protrudes from the seal member, it is possible to improve heat dissipation and to suppress deterioration of the electrolytic solution.

  Unlike this embodiment, when the folding parts 430 and 431 are provided only in a part of the outer periphery of the current collector 411, and the current collector 411 contains a resin, the current collector is used when the sealing member is heat-sealed. There is a possibility that 411 melts and comes out of the seal member, causing a short circuit between the current collectors. On the other hand, in this embodiment, since the folding parts 430 and 431 are provided along the entire outer periphery of the current collector 411, the above-described minute short circuit between the current collectors can be suppressed, which is preferable.

  Further, in this embodiment, the folding part 430 is formed by folding the protruding part 423 of the first seal member 422 and the protruding part 421 of the second seal member 420. The seismic vibration resistance is superior compared to the case of disposing another member.

  By using a metal material as the material of the current collector 411, conductivity, heat resistance, and strength can be improved. Further, by using a conductive resin as a material for the current collector 411, the current collector 411 can be reduced in weight, and the output density per weight of the battery can be improved. In addition, by using a conductive resin as a material for the current collector 411, elution like a metal material can be suppressed and solvent resistance can be improved.

  When the positive electrode active material layer 413 includes a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound as a positive electrode active material, a battery having excellent capacity and output characteristics can be configured.

  When the negative electrode active material layer 412 includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material as a negative electrode active material, a battery having excellent capacity and output characteristics can be configured.

  The bipolar lithium ion secondary battery of the fourth embodiment includes a liquid electrolyte or a gel electrolyte, and ions are transported more efficiently than an all-solid electrolyte that does not include an electrolytic solution. Can be planned.

<Fifth Embodiment>
Referring to FIG. 7, the fifth embodiment is substantially the same as the first embodiment, but the folding portion 533 is different from the first embodiment, and the first seal member 522A and the second seal member 520A are different. Touch.

  In the fifth embodiment, the end of one separator 540 protrudes from between the first seal member 522 and the second seal member 520A, and the first seal member 522A and the second seal member 520 The end of the other separator 540 protrudes from between. The first seal member 522 and the second seal member 520A seal one separator 540 by heat sealing. Further, the first seal member 522A and the second seal member 520 seal the other separator 540 by heat fusion.

  The folding portion 533 has a configuration in which the end portion of one separator 540 and the end portion of the other separator 540 are folded between the first protruding portion 523 and the second protruding portion 521. The total thickness of one separator 540 and the other separator 540 is preferably the same as the thickness of the current collector 511 or thicker than the current collector 511.

  The effect of 5th Embodiment is described.

  The bipolar lithium ion secondary battery has a folding part 533 and suppresses deformation of the first seal member 523 and the second seal member 521, so that it is possible to improve the sealing performance and thus improve the long-term reliability. .

  In this embodiment, the sum of the thickness of one separator 540 and the thickness of the other separator 540 is the same as the thickness of the current collector 511 or thicker than the current collector 511. That is, the thickness of the folding part 533 is greater than or equal to the gap. Accordingly, the surface pressure is easily applied, and the seal members are in close contact with each other, and the seal member and the separator 540 are in close contact with each other.

  In the present embodiment, since the end portion of the separator 540 protrudes from the seal member, it is possible to improve heat dissipation and to suppress deterioration of the electrolytic solution.

  Unlike this embodiment, when the folding part 533 is provided only in a part of the outer periphery of the current collector 511, and the current collector 511 contains a resin, the current collector 511 is used when the sealing member is heat-sealed. There exists a possibility that it melt | dissolves and it comes out to the outer side of a sealing member, and the micro short circuit of current collectors may arise. On the other hand, in this embodiment, since the folding part 533 is provided along the whole outer periphery of the electrical power collector 511, it can suppress the short circuit between the above electrical power collectors, and is preferable.

  By using a metal material as the material of the current collector 511, conductivity, heat resistance, and strength can be improved. Further, by using a conductive resin as a material for the current collector 511, the current collector 511 can be reduced in weight, and the output density per weight of the battery can be improved. In addition, by using a conductive resin as the material of the current collector 511, elution like a metal material can be suppressed and solvent resistance can be improved.

  When the positive electrode active material layer 513 includes a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound as a positive electrode active material, a battery having excellent capacity and output characteristics can be configured.

  When the negative electrode active material layer 512 includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material as a negative electrode active material, a battery having excellent capacity and output characteristics can be configured.

  The bipolar lithium ion secondary battery of the fifth embodiment includes a liquid electrolyte or a gel electrolyte, and ions are transported more efficiently than an all-solid electrolyte that does not include an electrolytic solution. Can be planned.

<Sixth Embodiment>
Referring to FIG. 8, the sixth embodiment is substantially the same as the fifth embodiment, except that it further includes a spacer 632 disposed between the first protruding portion 623 and the second protruding portion 621. Different from the fifth embodiment.

  The spacer 632 can be formed of, for example, a thermoplastic resin such as polypropylene or polyethylene, or a thermosetting resin such as epoxy. The spacer 632 preferably has a lower melting point than the first seal member and the second seal member. The thickness of the spacer 632 is preferably the same as the thickness of the current collector 611 or larger than the thickness of the current collector 611.

  The effect of 6th Embodiment is described.

  The bipolar lithium ion secondary battery according to the sixth embodiment includes the folding portion 633 and the spacer 632, and suppresses deformation of the first seal member and the second seal member. Reliability can be improved.

  In this embodiment, the separator 640 has the same thickness as the current collector 611 or thicker than the current collector 611, and the spacer 632 has the same thickness as the current collector 611, or Thicker than the thickness of the current collector 611. That is, the thickness of the folding part 633 and the thickness of the spacer 632 are greater than or equal to the gap. Accordingly, the surface pressure is easily applied, and the seal members are in close contact with each other, the seal member and the separator 640, and the seal member and the spacer 632 are in close contact with each other.

  In the present embodiment, since the end portion of the separator 640 protrudes from the seal member, it is possible to improve heat dissipation and consequently suppress deterioration of the electrolytic solution.

  Unlike this embodiment, when the folding part 633 is provided only in a part of the outer periphery of the current collector 611, and the current collector 611 contains a resin, the current collector 611 is used when the sealing member is heat-sealed. There exists a possibility that it melt | dissolves and it comes out to the outer side of a sealing member, and the micro short circuit of current collectors may arise. On the other hand, in the bipolar lithium ion secondary battery of this embodiment, since the folding portion 633 and the spacer 632 are provided along the entire outer periphery of the current collector 611, the above-described minute short circuit between the current collectors can be suppressed. preferable.

  By using a metal material as the material of the current collector 611, conductivity, heat resistance, and strength can be improved. Further, by using a conductive resin as the material of the current collector 611, the current collector 611 can be reduced in weight, and the output density per weight of the battery can be improved. In addition, by using a conductive resin as the material of the current collector 611, elution like a metal material can be suppressed and solvent resistance can be improved.

  When the positive electrode active material layer 613 includes a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound as a positive electrode active material, a battery having excellent capacity and output characteristics can be configured.

  When the negative electrode active material layer 612 includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material as a negative electrode active material, a battery having excellent capacity and output characteristics can be configured.

  The bipolar lithium ion secondary battery according to the sixth embodiment includes a liquid electrolyte or a gel electrolyte, and ions are transported more efficiently than an all-solid electrolyte that does not include an electrolytic solution. Can be planned.

<Seventh embodiment>
As shown in FIG. 9, the seventh embodiment has a configuration combining the configuration of the first embodiment and the configuration of the fifth embodiment. That is, the bipolar lithium ion secondary battery of the seventh embodiment includes a folding part 730 having the same configuration as that of the folding part 130 of the first embodiment and a folding structure having the same configuration as that of the folding part 533 of the fifth embodiment. Part 733.

  The folding part 730 is provided in the first seal member 722 and protrudes from the end of the current collector 711, and the folding part 730 is provided in the second seal member 720 and protrudes from the end of the current collector 711. The two protruding portions 721 are folded toward the end of the current collector 711. The sum of the thickness of the first seal member 722 and the thickness of the second seal member 720 is preferably equal to or greater than the thickness of the current collector 711. Preferably, the sum of the thickness of the first seal member 722 and the thickness of the second seal member 720 is equal to or less than the thickness of the current collector 711 + the thickness of the separator 740.

  The folding portion 733 has a configuration in which the end portion of one separator 740 and the end portion of the other separator 740 are folded between the first protruding portion 723 and the second protruding portion 721. The sum of the thickness of one separator 740 and the thickness of the other separator 740 is preferably the same as the thickness of the current collector 711 or thicker than the current collector 711.

  The effect of 7th Embodiment is described.

  The bipolar lithium ion secondary battery has a folding part 730 and a folding part 733, and suppresses deformation of the first seal member 722 and the second seal member 720, so that the sealing performance is improved, and thus long-term reliability is achieved. Can be improved.

  In the present embodiment, the sum of the thickness of the first seal member 722 and the thickness of the second seal member 720 is equal to or greater than the thickness of the current collector 711. The total thickness of one separator 740 and the other separator 740 is the same as the thickness of the current collector 711 or thicker than the current collector 711. That is, the thickness of the folding part 730 and the folding part 733 is more than a clearance. Accordingly, the surface pressure is easily applied, and the seal members are in close contact with each other and the seal member and the separator 740 are in close contact with each other.

  In the present embodiment, since the end portion of the separator 740 protrudes from the seal member, it is possible to improve heat dissipation and to suppress deterioration of the electrolyte.

  Unlike this embodiment, when the folding parts 730 and 733 are provided only at a part of the outer periphery of the current collector 711 and the current collector 711 contains a resin, the current collector is subjected to heat sealing. There is a possibility that 711 melts and comes out of the seal member, causing a short circuit between the current collectors. On the other hand, in this embodiment, since the folding portions 730 and 733 are provided along the entire outer periphery of the current collector 711, it is preferable that the above-described minute short-circuit between the current collectors can be suppressed.

  In this embodiment, since the folding part 730 is formed by folding the protruding part 723 of the first seal member 722 and the protruding part 721 of the second seal member 720, the spacers are integrated, for example, in the gap. The seismic vibration resistance is superior compared to the case of disposing another member.

  By using a metal material as the material of the current collector 711, conductivity, heat resistance, and strength can be improved. Further, by using a conductive resin as the material of the current collector 711, the current collector 711 can be reduced in weight, and the output density per weight of the battery can be improved. Further, by using a conductive resin as a material for the current collector 711, elution like a metal material can be suppressed and solvent resistance can be improved.

  When the positive electrode active material layer 713 includes a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound as a positive electrode active material, a battery having excellent capacity and output characteristics can be configured.

  When the negative electrode active material layer 712 includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material as a negative electrode active material, a battery having excellent capacity and output characteristics can be configured.

  The bipolar lithium ion secondary battery of the seventh embodiment includes a liquid electrolyte or a gel electrolyte, and ions are transported more efficiently than an all-solid electrolyte that does not include an electrolytic solution. Can be planned.

  Next, Examples 1 to 7 and a comparative example will be described. First, a configuration common to each example and comparative example will be described.

<Positive electrode active material layer>
In preparation of the positive electrode active material layer, a positive electrode active material, a conductive additive, a binder, and a slurry viscosity adjusting solvent were mixed at a predetermined ratio to prepare a positive electrode slurry. LiMn204 was used as the positive electrode active material. Acetylene black was used as a conductive aid. Polyvinylidene fluoride (PVDF) was used as a binder. N-methyl-2-pyrrolidone (NMP) was used as a slurry viscosity adjusting solvent. The ratio of each material is 85% by weight of the positive electrode active material, 5% by weight of the conductive additive, and 10% by weight of the binder.

  And the positive electrode slurry was apply | coated to one side of the electrical power collector comprised from the polyethylene (PE) containing an electroconductive filler, and it was made to dry, and formed the positive electrode active material layer. It pressed so that the thickness of a positive electrode active material layer might be set to 60 micrometers.

<Negative electrode active material layer>
In preparing the negative electrode active material layer, a negative electrode active material, a binder, and a slurry viscosity adjusting solvent were mixed at a predetermined ratio to prepare a negative electrode slurry. Hard carbon was used as the negative electrode active material. Polyvinylidene fluoride (PVDF) was used as a binder. N-methyl-2-pyrrolidone (NMP) was used as a slurry viscosity adjusting solvent. The proportion of each material is 90% by weight of the negative electrode active material and 10% by weight of the binder.

  And the negative electrode slurry was apply | coated to the single side | surface of the collector comprised from the polyethylene (PE) containing an electroconductive filler, and it was made to dry and the negative electrode active material layer was formed. It pressed so that the thickness of a negative electrode active material layer might be set to 50 micrometers. In this way, a bipolar electrode is produced in which a positive electrode active material layer is formed on one side of a conductive polymer film as a current collector and a negative electrode active material layer is formed on one side.

<Current collector>
As a conductive layer, a conductive polymer material in which a carbon material was dispersed in a polyethylene resin was formed into a film by stretching and used. The thickness is 100 μm.

  The bipolar electrode was cut to a size of 140 × 90 mm. The peripheral part 10 mm of each of the positive electrode active material layer and the negative electrode active material layer was sealed. That is, the dimensions of the positive electrode active material layer and the negative electrode active material layer were 120 × 70 mm, respectively.

<Electrolyte>
As an electrolytic solution, 1M LiPF ₆ / EC + DEC (solvent volume ratio 1: 1) was used. Here, EC is ethylene carbonate, and DEC is diethyl carbonate.

<Separator>
A separator made of polyethylene (PE) was used. The thickness of the separator is 35 μm.

<Seal member>
As shown in FIG. 10, the seal member is a frame type and is a polyethylene (PE) film. The seal member is disposed around the positive electrode active material layer and the negative electrode active material layer of the bipolar electrode. The seal member has a substantially rectangular shape, and one side thereof protrudes from the end of the current collector. One side of the seal member provided with the protruding portion is used as a liquid injection portion for injecting the electrolytic solution.

<Example 1>
In Example 1, a spacer was inserted into a gap (see FIG. 1A) between the protruding portion and the protruding portion of the seal member protruding from the end portion of the current collector. The spacer is made of polypropylene (PP). The spacer thickness is 70 μm and the other dimensions are 160 × 30 μm. Six bipolar electrodes were produced, and spacers were inserted into the gaps between the protruding portion and the protruding portion for all bipolar electrodes.

  After inserting a spacer between the protruding part and the protruding part, press and apply heat and pressure to three sides of the sealing member different from the liquid injection part (one side where the protruding part is provided and the spacer is inserted) The member was fused to the current collector. The pressing conditions are 0.1 MPa, 140 ° C. and 5 seconds.

  Six bipolar electrodes were stacked. Heat and pressure are applied to the three sides of the sealing member different from the liquid injection part from the stacking direction and pressed, and the overlapping sealing members are fused together. The pressing conditions are 0.2 MPa, 140 ° C., and 5 seconds. At this stage, the liquid injection part remains open, and the laminated body of bipolar electrodes has a bag-like configuration in which three sides of the sealing member are sealed.

  After injecting the electrolytic solution from the liquid injection part, the liquid injection part was closed by vacuum-sealing to produce a bipolar lithium ion secondary battery. In vacuum sealing, a bipolar electrode laminate is sandwiched from the lamination direction by an Al plate as a current collector plate. Then, the laminate of the Al plate and the bipolar electrode was covered with an aluminum laminate film, pressurized by atmospheric pressure, and vacuum sealed. The vacuum sealing increases the contact between the Al plate and the bipolar electrode.

  The thickness of the Al plate is 100 μm. Moreover, the dimension of the Al plate is 130 × 80 mm, and covers the entire projection surface on which the bipolar electrode is projected in the thickness direction. Further, a part of the Al plate extends to form a positive electrode tab or a negative electrode tab.

<Example 2>
Example 2 is substantially the same as Example 1, except that spacers are not inserted into the gaps between the protruding part and the protruding part for all six bipolar electrodes, but only for the two bipolar electrodes, A spacer was inserted between the protruding part. When the bipolar electrodes were stacked, the two bipolar electrodes with the spacers inserted were arranged on the outermost side in the stacking direction. That is, the two bipolar electrodes with the spacer inserted sandwich the other four bipolar electrodes.

<Example 3>
Example 3 corresponds to the first embodiment described above. That is, the folding part was formed by folding the protruding part toward the end of the current collector. Six bipolar electrodes were produced, and folds were formed for all bipolar electrodes.

  After forming the folding part, heat and pressure are applied to three sides of the sealing member different from the liquid injection part (one side where the protruding part is provided and the folding part is formed), and the sealing member is fused to the current collector. I let you. The pressing conditions are 0.1 MPa, 140 ° C. and 5 seconds.

  Six bipolar electrodes were stacked. Heat and pressure are applied to the three sides of the sealing member different from the liquid injection part from the stacking direction and pressed, and the overlapping sealing members are fused together. The pressing conditions are 0.2 MPa, 140 ° C., and 5 seconds. The injection of the electrolytic solution and the vacuum sealing are the same as in Example 1.

<Example 4>
Example 4 corresponds to the fifth embodiment described above. That is, the folded portion was formed by folding the end portions of the two separators between the protruding portion and the protruding portion.

  In the same manner as in Example 1, a sealing member was fused to the bipolar electrode, and then six bipolar electrodes were laminated. And the edge part of two separators was folded between the protrusion part and the protrusion part. Heat and pressure are applied from the laminating direction to three sides of the sealing member different from the liquid injection part (one side of the sealing member provided with the protruding part), and the overlapping sealing members are fused. The pressing conditions are 0.2 MPa, 140 ° C., and 5 seconds. The injection of the electrolytic solution and the vacuum sealing are the same as in Example 1.

<Example 5>
Example 5 corresponds to the second embodiment described above. That is, the folding part was formed by folding the end part of one separator between the protruding part and the protruding part.

  In the same manner as in Example 1, a sealing member was fused to the bipolar electrode, and then six bipolar electrodes were laminated. And the edge part of one separator was folded between the protrusion part and the protrusion part. Heat and pressure are applied from the laminating direction to three sides of the sealing member different from the liquid injection part (one side of the sealing member provided with the protruding part), and the overlapping sealing members are fused. The pressing conditions are 0.2 MPa, 140 ° C., and 5 seconds. The injection of the electrolytic solution and the vacuum sealing are the same as in Example 1.

<Example 6>
Example 6 corresponds to the third embodiment described above. That is, a folded portion was formed by folding the end portion of one separator between the protruding portion and the protruding portion, and a spacer was inserted between the protruding portion and the protruding portion.

  In the same manner as in Example 1, a sealing member was fused to the bipolar electrode, and then six bipolar electrodes were laminated. And the edge part of one separator was folded between the protrusion part and the protrusion part, and the spacer was inserted. The spacer is the same as that described in the first embodiment.

  Heat and pressure were applied from the laminating direction to three sides of the sealing member different from the liquid injection part (one side of the sealing member provided with the protruding part), and the overlapping sealing members were fused. The pressing conditions are 0.2 MPa, 140 ° C., and 5 seconds. The injection of the electrolytic solution and the vacuum sealing are the same as in Example 1.

<Example 7>
Example 7 is substantially the same as Example 1, but the spacer thickness differs between Example 7 and Example 1. In Example 7, the thickness of the spacer is 110 μm. Since the seventh embodiment is the same as the first embodiment with respect to the other configurations and the like, the duplicate description is omitted.

<Comparative example>
The comparative example is substantially the same as the first embodiment, but differs from the first embodiment in that no spacer is provided. That is, in the comparative example, there is no spacer, and there is a gap between the protruding portion and the protruding portion.

  In the same manner as in Example 1, a sealing member was fused to the bipolar electrode, and then six bipolar electrodes were laminated. The press after the lamination, the injection of the electrolytic solution, and the vacuum sealing are the same as in Example 1.

  Examples and comparative examples are summarized in Table 1.

  About each of an Example and a comparative example, the capacity | capacitance maintenance factor was calculated | required after battery preparation. The capacity retention ratio is (discharge capacity after storage test / battery capacity at the time of initial discharge) × 100%. First, initial charge / discharge was performed at 0.5 C for 5 hours. Here, the upper limit voltage in each unit cell layer is 4.2V. Then, the storage test of 25 degreeC and 45 degreeC was performed for 1 week by SOC (State Of Charge) 100%, and the capacity | capacitance measurement after a storage was performed by the charge / discharge measurement of 0.5C. The evaluation results are shown in Table 2.

  From the evaluation results, it can be confirmed that the capacity retention rate of the example is higher than that of the comparative example. Since it can be said that the higher the capacity retention rate, the smaller the loss of capacity and the more it is possible to prevent leakage of the electrolyte solution, the evaluation results show that the folded portion and the spacer are effective in improving the sealing performance.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the bipolar secondary battery is preferably a lithium ion secondary battery in terms of energy density and output density, but is not limited thereto. The bipolar secondary battery may be, for example, a sodium ion secondary battery, a potassium ion secondary battery, a nickel metal hydride secondary battery, or a nickel cadmium secondary battery.

  Moreover, the bipolar secondary battery may have the folding part 231 of the second embodiment and the folding part 533 of the fifth embodiment.

100 Bipolar lithium ion secondary battery (corresponding to a bipolar secondary battery),
101, 103 current collector plate,
102 power generation elements,
104 positive electrode tab,
106 negative electrode tab,
108 exterior materials,
110, 210, 310, 410, 510, 610, 710 Bipolar electrode,
111, 211, 311, 411, 511, 611, 711 current collector,
112, 212, 312, 412, 512, 612, 712 negative electrode active material layer,
113, 213, 313, 413, 513, 613, 713 positive electrode active material layer,
122, 222, 322, 422, 522, 622, 722 first sealing member,
222A, 522A first seal member,
123, 223, 323, 423, 523, 623, 723, first protruding portion,
120, 220, 320, 420, 520, 620, 720 second sealing member,
220A, 520A second seal member,
121, 221, 321, 421, 521, 621, 721, second protruding portion,
140 separator,
240, 340, 440 separator (corresponding to the separator of claim 2)
540, 640, 740 Separator (corresponding to the separator of claim 3)
130, 430, 730 Folding part (corresponding to the folding part of claim 1),
231, 331, 431 Folding part (corresponding to the folding part of claim 2),
533, 633, 733 Folding part (corresponding to the folding part of claim 3),
332, 632 Spacer.

Claims (10)

A bipolar secondary battery in which a positive electrode active material layer is formed on one surface of a current collector and a negative electrode active material layer is formed on the other surface, and a plurality of bipolar electrodes are stacked via a separator,
A first seal member disposed on the one surface so as to surround the positive electrode active material layer;
A second seal member disposed on the other surface surrounding the negative electrode active material layer;
A first protruding portion provided on the first seal member and protruding from an end of the current collector;
A second protruding portion provided on the second seal member and protruding from an end of the current collector;
A bipolar secondary battery comprising: a first protruding portion and a bent portion formed by folding the second protruding portion toward an end of the current collector. A bipolar secondary battery in which a positive electrode active material layer is formed on one surface of a current collector and a negative electrode active material layer is formed on the other surface, and a plurality of bipolar electrodes are stacked via a separator,
A first seal member disposed on the one surface so as to surround the positive electrode active material layer;
A second seal member disposed on the other surface surrounding the negative electrode active material layer;
A first protruding portion provided on the first seal member and protruding from an end of the current collector;
A second protruding portion provided on the second seal member and protruding from an end of the current collector;
A folded portion in which an end portion of the separator protruding from between the first seal member and the second seal member is folded between the first protruding portion and the second protruding portion; A bipolar secondary battery. A bipolar secondary battery in which a positive electrode active material layer is formed on one surface of a current collector and a negative electrode active material layer is formed on the other surface, and a plurality of bipolar electrodes are stacked via a separator,
A first seal member disposed on the one surface so as to surround the positive electrode active material layer;
A second seal member disposed on the other surface surrounding the negative electrode active material layer;
A first protruding portion provided on the first seal member and protruding from an end of the current collector;
A second protruding portion provided on the second seal member and protruding from an end of the current collector;
One end of the separator that protrudes from between the first seal member and the second seal member, and another separator that protrudes from between the first seal member and the second seal member. A bipolar secondary battery, the end portion of which includes a folded portion formed by folding between the first protruding portion and the second protruding portion.   The bipolar secondary battery which has at least any one of the folding part of Claim 1, the folding part of Claim 2, and the folding part of Claim 3.   The bipolar secondary battery according to any one of claims 1 to 4, further comprising a spacer disposed between the first protruding portion and the second protruding portion.   The sum of the thickness of the first seal member and the thickness of the second seal member and / or the thickness of the spacer is equal to or greater than the thickness of the current collector. The bipolar secondary battery according to one.   The bipolar secondary battery according to any one of claims 1 to 6, wherein the current collector includes a metal material or a conductive resin.   The bipolar secondary battery according to claim 1, wherein the positive electrode active material layer includes a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium transition metal sulfate compound. .   The bipolar secondary battery according to any one of claims 1 to 8, wherein the negative electrode active material layer includes a carbon material, a lithium-transition metal compound, a metal material, or a lithium-metal alloy material.   The bipolar secondary battery according to any one of claims 1 to 9, comprising a liquid electrolyte or a gel electrolyte.

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