Power storage unit and power storage device

Abstract

This power storage unit comprises: a first electrode body and a second electrode body in each of which a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector foil and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector foil are stacked; a first electrolyte and a second electrolyte composed of a potassium ion nonaqueous electrolyte or a sodium ion nonaqueous electrolyte; and a container that accommodates the first electrode body, the second electrode body, the first electrolyte, and the second electrolyte. The container integrally includes a first accommodation part that accommodates the first electrode body and the first electrolyte in a state in which the negative electrode plate of the first electrode body is electrically connected, and a second accommodation part that accommodates the second electrode body and the second electrolyte in a state in which the positive electrode plate of the second electrode body is electrically connected. The first accommodation part includes a positive electrode terminal insulated from the first accommodation part and electrically connected to the positive electrode plate of the first electrode body. The second accommodation part includes a negative electrode terminal insulated from the second accommodation part and electrically connected to the negative electrode plate of the second electrode body. The positive electrode current collector foil, the negative electrode current collector foil, the container, the positive electrode terminal, and the negative electrode terminal are formed of aluminum or an aluminum alloy.

Description

Energy storage unit and energy storage device

[0001] The present invention relates to an electricity storage unit and an electricity storage device.

[0002] Conventionally, a prismatic secondary battery included in a battery pack includes a wound electrode assembly in which a positive electrode plate and a negative electrode plate are wound, and a prismatic outer casing that houses the wound electrode assembly. The positive electrode plate is formed by applying a positive electrode active material to an aluminum foil, and the negative electrode plate is formed by applying a negative electrode active material to a copper foil (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-180650

[0004] In recent years, there has been a demand to reduce the amount of copper used in order to prevent short circuits caused by copper.

[0005] Therefore, an object of the present invention is to provide an electricity storage unit or the like that can reduce the amount of copper used.

[0006] An energy storage unit according to one aspect of the present invention includes a first electrode body and a second electrode body in which a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector foil and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector foil are stacked together; a first electrolyte and a second electrolyte each made of a potassium ion non-aqueous electrolyte or a sodium ion non-aqueous electrolyte; and a container for accommodating the first electrode body, the second electrode body, the first electrolyte, and the second electrolyte, wherein the container includes a first storage portion for accommodating the first electrode body and the first electrolyte in a state in which the negative electrode plate of the first electrode body is electrically connected to the first storage portion, and a second storage portion for accommodating the first electrolyte in a state in which the positive electrode plate of the second electrode body is electrically connected to the first storage portion. a second housing portion that houses the second electrode body and the second electrolyte in a connected state, the first housing portion being arranged outside the first housing portion insulated from the first housing portion and including a positive electrode terminal electrically connected to the positive electrode plate of the first electrode body; the second housing portion being arranged outside the second housing portion insulated from the second housing portion and including a negative electrode terminal electrically connected to the negative electrode plate of the second electrode body; and the positive electrode current collector foil, the negative electrode current collector foil, the container, the positive electrode terminal, and the negative electrode terminal are formed from aluminum or an aluminum alloy.

[0007] The present invention can provide an electricity storage unit or the like that can reduce the amount of copper used.

[0008] FIG. 1 is a perspective view showing the appearance of an energy storage device according to an embodiment. FIG. 2 is an exploded perspective view showing each component of an energy storage device according to an embodiment when disassembled. FIG. 3 is a perspective view showing each component of an energy storage unit according to an embodiment when disassembled. FIG. 4 is a perspective view showing a configuration of a first electrode body according to an embodiment. FIG. 5 is a cross-sectional view schematically showing an internal configuration of an energy storage unit according to an embodiment. FIG. 6 is a perspective view showing an electrical connection structure of two adjacent energy storage units out of a plurality of energy storage units according to an embodiment. FIG. 7A is a perspective view showing a container according to Modification 2. FIG. 7B is a perspective view showing a container according to Modification 2. FIG. 8 is an explanatory diagram showing an example of connection between a first balancer circuit and a second balancer circuit according to Modification 3.

[0009] (1) An energy storage unit according to one aspect of the present invention includes a first electrode body and a second electrode body, each of which is formed by stacking a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector foil and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector foil; a first electrolyte and a second electrolyte, each of which is a potassium ion non-aqueous electrolyte or a sodium ion non-aqueous electrolyte; and a container that accommodates the first electrode body, the second electrode body, the first electrolyte, and the second electrolyte, wherein the container includes a first storage portion that accommodates the first electrode body and the first electrolyte in a state where the negative electrode plate of the first electrode body is electrically connected; and a second storage portion that accommodates the first electrolyte and the first electrolyte in a state where the positive electrode plate of the second electrode body is electrically connected. the second electrode body and a second accommodation portion that accommodates the second electrolyte in a state where the first accommodation portion is connected to the first accommodation portion, the first accommodation portion being arranged outside the first accommodation portion in a state insulated from the first accommodation portion and comprising a positive electrode terminal that is electrically connected to the positive electrode plate of the first electrode body, the second accommodation portion being arranged outside the second accommodation portion in a state insulated from the second accommodation portion and comprising a negative electrode terminal that is electrically connected to the negative electrode plate of the second electrode body, and the positive electrode current collecting foil, the negative electrode current collecting foil, the container, the positive electrode terminal, and the negative electrode terminal are formed of aluminum or an aluminum alloy.

[0010] According to the energy storage unit described in (1) above, the first storage portion of the container contains a first electrolyte, and the second storage portion contains a second electrolyte. Here, the first electrolyte and the second electrolyte are potassium ion nonaqueous electrolytes or sodium ion nonaqueous electrolytes that do not alloy with aluminum. Therefore, the positive electrode current collector foil, the negative electrode current collector foil, the container, the positive electrode terminal, and the negative electrode terminal can be made of aluminum or an aluminum alloy. Therefore, the amount of copper used in the entire energy storage unit can be reduced.

[0011] (2) The energy storage device may include the energy storage unit described in (1), a first balancer circuit connected to the container and the positive electrode terminal, and a second balancer circuit connected to the container and the negative electrode terminal.

[0012] According to the storage device described in (2) above, the first balancer circuit is connected to the container and the positive electrode terminal, and the second balancer circuit is connected to the container and the negative electrode terminal, so that the voltage difference between the first electrode body and the second electrode body can be suppressed, and overcharging of one of the electrode bodies can be suppressed.

[0013] (3) In the energy storage device described in (2) above, a plurality of the energy storage units may be arranged, and of two adjacent energy storage units, the positive electrode terminal of one energy storage unit and the negative electrode terminal of the other energy storage unit may be electrically connected in series by a bus bar.

[0014] According to the energy storage device described in (3) above, even when two adjacent energy storage units are electrically connected in series with the positive electrode terminal of one energy storage unit and the negative electrode terminal of the other energy storage unit by a bus bar, the amount of copper used is reduced, so that short circuits caused by copper can be reduced and reliability can be improved.

[0015] (Embodiments) Hereinafter, with reference to the drawings, a description will be given of an energy storage unit and the like according to embodiments of the present invention (including modified examples thereof). Note that the embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. In each drawing, dimensions and the like are not strictly illustrated. In each drawing, the same or similar components are denoted by the same reference numerals. The names of the components (each component) in this embodiment are those used in this embodiment and may differ from the names of the components (each component) in the background art.

[0016] In the following description and drawings, the longitudinal direction of the container of the energy storage unit, and the direction along the winding axis of the electrode body provided in the energy storage unit, are defined as the X-axis direction. The thickness direction of the container of the energy storage unit is defined as the Y-axis direction. The direction in which the bottom and top surfaces of the container of the energy storage unit are aligned, or the up-down direction, is defined as the Z-axis direction. The X-axis direction, Y-axis direction, and Z-axis direction intersect with each other (orthogonal in this embodiment). Depending on the mode of use, the Z-axis may not be the up-down direction, but for ease of explanation, the following description will be made assuming that the Z-axis direction is the up-down direction. In the following description, when the term "insulation" is used, it means "electrical insulation". An insulating material has a volume resistivity of 1×10 ６ Ωm or more is preferable, and 1×10 ７ Ωm or more is more preferable, and 1×10 １０ More preferably, it is Ωm or more.

[0017] In the following description, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the direction or attitude is not strictly that. "Two directions are perpendicular" does not only mean that the two directions are completely perpendicular, but also means that the directions are substantially perpendicular, i.e., there is a difference of about a few percent.

[0018] [Electricity Storage Device] First, a schematic configuration of an electricity storage device 1 according to the present embodiment will be described. Fig. 1 is a perspective view showing the appearance of the electricity storage device 1 according to the embodiment. Fig. 2 is an exploded perspective view showing each component of the electricity storage device 1 according to the embodiment.

[0019] The power storage device 1 is a device capable of charging with electricity from an external source and discharging electricity to an external source, and in this embodiment, has a substantially rectangular parallelepiped shape. The power storage device 1 is used as a battery for driving or starting the engine of a moving object such as an automobile, a motorcycle, a personal watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, an automatic guided vehicle (AGV), or a rolling stock for an electric railway. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicle. Examples of the electric railway vehicle include a train, a monorail, a linear motor car, and a hybrid train equipped with both a diesel engine and an electric motor. The power storage device 1 may also be used as a stationary battery for home or business use.

[0020] As shown in Fig. 1 , the energy storage device 1 includes an exterior body 2. As shown in Fig. 2 , a plurality of energy storage units 10, a plurality of spacers 20, a plurality of bus bars, and the like are housed inside the exterior body 2. The energy storage device 1 also includes external terminals 11 (positive electrode external terminals and negative electrode external terminals) for electrically connecting to an external device. In addition to the above-mentioned components, the energy storage device 1 may also include restraining members (end plates, side plates, etc.) that restrain the plurality of energy storage units 10, bus bar holders that hold the bus bars, bus bar covers, circuit boards that monitor or control the charge state, discharge state, etc. of the energy storage units 10, and electrical components such as relays, fuses, shunt resistors, and connectors.

[0021] The exterior body 2 is a rectangular parallelepiped (box-shaped) container (module case) that constitutes the exterior body (housing, outer shell) of the energy storage device 1. A rectangular parallelepiped is a hexahedron with all faces formed of rectangles or squares. The exterior body 2 is disposed outside the plurality of energy storage units 10 and the plurality of spacers 20, etc., to house the plurality of energy storage units 10, the plurality of spacers 20, etc., and protect them from impacts and the like. The exterior body 2 is a metal exterior body formed of metal members such as aluminum, aluminum alloy, stainless steel, iron, and plated steel sheet. The exterior body 2 may be formed of an insulating material, such as any resin material that can be used for the spacers 20 described below. If the exterior body 2 is formed of a conductive material, the inner surface of the exterior body 2 may be coated with an insulating material to ensure insulation from the energy storage units 10.

[0022] 2 , the exterior body 2 includes an exterior body main body 30 that constitutes the main body of the exterior body 2, and an exterior body lid 40 that constitutes the lid of the exterior body 2. The exterior body main body 30 is a rectangular cylindrical housing (chassis) with a bottom and an opening 31 formed in the positive direction of the Z axis, and houses a plurality of energy storage units 10, a plurality of spacers 20, and the like. Although not shown, the exterior body 2 may be formed with an exhaust port that connects the inside and outside of the exterior body 2. This exhaust port exhausts gas discharged from the energy storage units 10 to the outside of the exterior body 2.

[0023] Specifically, the exterior body main body 30 includes a bottom wall 32 and a side wall 33. The bottom wall 32 is a flat, rectangular portion located at the end of the exterior body main body 30 in the negative Z-axis direction. The side wall 33 is a rectangular, annular wall extending in the positive Z-axis direction from the outer peripheral edge of the bottom wall 32, and is provided continuously around the entire circumference of the bottom wall 32. The opening 31 is located inside the side wall 33.

[0024] The exterior body lid 40 is a flat, rectangular member that closes the rectangular opening 31 of the exterior body main body 30. The exterior body main body 30 and the exterior body lid 40 are joined by welding, fusing, screwing, or the like to form a tight seal (sealed). The exterior body main body 30 and the exterior body lid 40 may be formed of members made of the same material, or may be formed of members made of different materials. On the top surface of the exterior body lid 40, a pair of external terminals 11 are arranged side by side in the Y-axis direction at the end in the positive direction of the X-axis.

[0025] The spacer 20 is a flat plate-like member that is arranged alongside the energy storage unit 10 in the Y-axis direction and provides insulation and / or heat between the energy storage unit 10 and other members. The spacer 20 is an insulating plate or heat insulating plate that is arranged adjacent to the energy storage unit 10 in the positive or negative Y-axis direction of the energy storage unit 10 and provides insulation and / or heat between the energy storage units 10 and each other or between the energy storage unit 10 and the exterior body 2. The spacer 20 is formed from an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or a composite material containing any of these materials and a filler added thereto, or a material having heat insulating properties such as mica.

[0026] Of the spacers 20, the spacers 20 arranged between adjacent energy storage units 10 are intermediate spacers, and the two spacers 20 arranged at the ends of the plurality of energy storage units 10 in the Y-axis direction are end spacers. All the spacers 20 may be formed of the same material, or some of the spacers 20 may be formed of different materials. When viewed from the Y-axis direction, the spacers 20 are formed in the shape of a rectangular parallelepiped that is elongated in the X-axis direction.

[0027] The spacers 20 may be cooling plates. In this case, the spacers 20 are made of a material with high thermal conductivity, such as metal. In this case, it is preferable that the surfaces of the spacers 20 are subjected to an insulating treatment. All of the plurality of spacers 20 may be cooling plates, or at least one of them may be a cooling plate.

[0028] The busbars are connected (joined) to terminals (first terminals 300a and second terminals 300b described below) of the multiple energy storage units 10. Specifically, the multiple busbars connect the terminals of the multiple energy storage units 10 to each other and electrically connect the terminals of the end energy storage units 10 to the external terminal 11. That is, one busbar may connect the terminals of the multiple energy storage units 10 to each other, or may connect the terminals to the external terminal 11. The connection form of the busbars is not particularly limited, and the multiple energy storage units 10 may be connected in series or in parallel in any combination, or all of the energy storage units 10 may be connected in series or in parallel. The busbars and the terminals are connected (joined) by welding or the like, but the connection form is not particularly limited. The busbars are formed of a conductive metal member such as aluminum, an aluminum alloy, copper, a copper alloy, or nickel, or a combination thereof, or a conductive material other than a metal. However, from the viewpoint of reducing the amount of copper used, it is preferable that the busbars be formed of a material other than copper or a copper alloy. From the viewpoint of reducing the weight of the bus bar, it is more preferable that the bus bar be made of aluminum or an aluminum alloy.

[0029] [Electricity storage unit] Next, the configuration of the electricity storage unit 10 in this embodiment will be described. The electricity storage unit 10 is a secondary battery that can charge and discharge electricity. More specifically, the electricity storage unit 10 is a non-aqueous electrolyte secondary battery such as a potassium ion secondary battery, and is a non-pouch type battery. The electricity storage unit 10 may also be a capacitor. The electricity storage units 10 are arranged in the Y-axis direction.

[0030] Fig. 3 is a perspective view showing each component of the energy storage unit 10 according to the embodiment when disassembled. As shown in Fig. 3, the energy storage unit 10 includes a container 100, a first terminal 300a, a second terminal 300b, a first outer gasket 400a, and a second outer gasket 400b. Housed inside the container 100 are a first inner gasket 500a, a second inner gasket 500b, a first terminal current collector 600a, a second terminal current collector 600b, a first housing current collector 650a, a second housing current collector 650b, a first electrode body 700a, and a second electrode body 700b.

[0031] The container 100 is a rectangular container having an outer shape (rectangular parallelepiped) based on a rectangular parallelepiped. Specifically, the container 100 has an outer shape of a rectangular parallelepiped that is elongated in the X-axis direction. The container 100 includes a container body 110, a lid 120, and a bottom body 130, and the container body 110, the lid 120, and the bottom body 130 are assembled together to form the rectangular parallelepiped shape.

[0032] The container body 110 is a rectangular parallelepiped cylinder with both ends in the Z-axis direction open. The container body 110 has a partition wall 111 in the middle in the X-axis direction, which divides the internal space of the container body 110 into two spaces, each of which penetrates in the Z-axis direction. The container body 110 is formed by extrusion molding.

[0033] The lid 120 is a rectangular metal plate that is long in the X-axis direction and closes two openings in the positive direction of the Z-axis of the container body 110. A first through-hole 121a through which the first terminal 300a passes is formed at the end of the lid 120 in the negative direction of the X-axis. Meanwhile, a second through-hole 121b through which the second terminal 300b passes is formed at the end of the lid 120 in the positive direction of the X-axis.

[0034] When the lid body 120 and the bottom body 130 are welded and assembled to the container body 110, a first storage section 140a is formed inside the container 100 in the negative direction of the X-axis based on the partition wall 111, and a second storage section 140b is formed in the positive direction of the X-axis based on the partition wall 111.

[0035] The first housing portion 140a accommodates a first inner gasket 500a, a first terminal current collector 600a, a first housing portion current collector 650a, a first electrode assembly 700a, and a first electrolyte (not shown), while the second housing portion 140b accommodates a second inner gasket 500b, a second terminal current collector 600b, a second housing portion current collector 650b, a second electrode assembly 700b, and a second electrolyte (not shown).

[0036] Although not shown here, a first liquid injection portion and a first gas exhaust valve are formed in the lid 120 or the bottom 130 at a location corresponding to the first storage portion 140a. The first liquid injection portion is a portion for injecting the first electrolyte into the first storage portion 140a during manufacturing. The first gas exhaust valve is a safety valve that releases pressure in the event of an excessive increase in pressure inside the first storage portion 140a. Similarly, a second liquid injection portion for injecting the second electrolyte into the second storage portion 140b and a second gas exhaust valve, which is a safety valve that releases pressure in the second storage portion 140b, are formed in the lid 120 or the bottom 130 at a location corresponding to the second storage portion 140b.

[0037] With this configuration, the container 100 accommodates the first electrode body 700a and the like in the first accommodation portion 140a, accommodates the second electrode body 700b and the like in the second accommodation portion 140b, and then the container body 110, the lid body 120, and the bottom body 130 are joined by welding or the like, thereby sealing the interior. The container 100 (container body 110, lid body 120, and bottom body 130) is made of aluminum or an aluminum alloy.

[0038] The first electrolyte and the second electrolyte are potassium ion non-aqueous electrolytes (nonaqueous electrolytic solutions). Specifically, the first electrolyte and the second electrolyte are composed of a potassium salt dissolved primarily in a non-aqueous solvent. When the container 100 and the negative electrode plate 750 of the first electrode body 700a are electrically connected, the lithium salt may alloy with the container 100, so it is preferable that the lithium salt does not exceed the impurity level.

[0039] The non-aqueous solvent can be appropriately selected from known non-aqueous solvents. Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate (EC) or propylene carbonate (PC), chain carbonates such as ethyl methyl carbonate (EMC), carboxylic acid esters, phosphate esters, sulfonic acid esters, ethers, amides, and nitriles. The non-aqueous solvent may be a compound in which some of the hydrogen atoms contained in these compounds are substituted with halogen.

[0040] Potassium salts include potassium hexafluorophosphate (KPF ６ A plurality of potassium salts may be used. The first electrolyte may contain an additive such as biphenyl.

[0041] In addition to the above components, the inside of the first storage section 140a and the second storage section 140b may contain spacers arranged to the side, above, or below the first electrode body 700a or the second electrode body 700b, or insulating films that encase the first electrode body 700a or the second electrode body 700b, etc.

[0042] Next, the components corresponding to the first housing portion 140a will be described in detail. The components corresponding to the first housing portion 140a are the first terminal 300a, the first terminal current collector 600a, the first housing portion current collector 650a, the first outer gasket 400a, the first inner gasket 500a, and the first electrode body 700a.

[0043] The first terminal 300a is electrically connected to the first electrode body 700a via the first terminal current collector 600a. The first terminal 300a is made of aluminum or an aluminum alloy. The first terminal 300a is connected (joined) to the first terminal current collector 600a by crimping, welding, or the like, and is attached to the cover 120.

[0044] In the present embodiment, the first terminal 300a has a terminal body 310a and a shaft 320a protruding from the terminal body 310a. The terminal body 310a is a portion that protrudes outward (in the positive direction of the Z axis) from the lid 120. The shaft 320a is inserted into a first through-hole 121a of the lid 120 and penetrates the lid 120. The shaft 320a is connected (joined) to the first terminal current collector 600a by being crimped while passing through the lid 120, the first outer gasket 400a, the first inner gasket 500a, and the first terminal current collector 600a.

[0045] The first terminal current collector 600a is disposed in the first accommodation portion 140a in the negative X-axis direction of the first electrode body 700a. The first terminal current collector 600a is connected (joined) to the first electrode body 700a and the first terminal 300a, and is a conductive current collecting member that electrically connects the first electrode body 700a and the first terminal 300a. The first terminal current collector 600a is made of aluminum or an aluminum alloy.

[0046] The first storage unit current collector 650a is disposed in the first storage unit 140a in the positive direction of the X axis of the first electrode body 700a. The first storage unit current collector 650a is connected (joined) to the first electrode body 700a and the lid body 120, and is a conductive current collecting member that electrically joins the first electrode body 700a and the container 100. The first storage unit current collector 650a is made of aluminum or an aluminum alloy.

[0047] The first outer gasket 400a is a plate-shaped, rectangular insulating sealing member that is disposed between the lid 120 and the first terminal 300a and provides insulation and sealing between the lid 120 and the first terminal 300a. The first inner gasket 500a is a plate-shaped, rectangular insulating sealing member that is disposed between the lid 120 and the first terminal current collector 600a in the first storage section 140a and provides insulation and sealing between the lid 120 and the first terminal current collector 600a. The first outer gasket 400a and the first inner gasket 500a are examples of an insulating positive electrode insulator that insulates the first terminal 300a and the first terminal current collector 600a from the container 100. The first outer gasket 400a and the first inner gasket 500a are formed from an electrically insulating resin such as PP, PE, PS, PPS, PPE (including modified PPE), PET, PBT, PEEK, PFA, PTFE, PES, ABS resin, or a composite material made by adding filler to any of these.

[0048] Fig. 4 is a perspective view showing the configuration of a first electrode assembly 700a according to an embodiment. Specifically, Fig. 4 shows the configuration of the first electrode assembly 700a in a partially developed state, with the wound electrode plates in the first electrode assembly 700a. As shown in Fig. 4, the first electrode assembly 700a has a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762.

[0049] The positive electrode plate 740 is an electrode plate in which a positive electrode active material layer 742 made of a positive electrode active material is disposed on both sides of a positive electrode current collector foil 741, which is a long strip-shaped metal foil. The positive electrode current collector foil 741 is formed from aluminum or an aluminum alloy. Any known material can be used as the positive electrode active material as long as it is capable of absorbing and releasing potassium ions. Specifically, KMO is used as the positive electrode active material. ２ Layered oxides such as KMPO ４ , K. ４ M ３ (P.O. ４ ) P ２ O ７ Polyanionic metal oxides such as KxM(CN) ６Examples of the positive electrode active material include potassium hexacyanometallates such as those mentioned above. Here, "M" is a metal element such as Ti, V, Cr, Fe, Co, Ni, Cu, and Zn. Furthermore, the positive electrode active material is preferably a positive electrode active material that can be doped and dedoped with potassium ions.

[0050] The negative electrode plate 750 is an electrode plate in which a negative electrode active material layer 752 made of a negative electrode active material is disposed on both sides of a negative electrode current collector foil 751, which is a long strip of metal foil. The negative electrode current collector foil 751 is formed of aluminum or an aluminum alloy. Any known material can be used as the negative electrode active material as long as it is capable of absorbing and releasing potassium ions. Specific examples of the negative electrode active material include carbon materials capable of absorbing and releasing potassium ions, simple substances or intermetallic compounds of elements that alloy with potassium, and oxides containing these elements. The negative electrode active material is preferably a negative electrode active material that can be doped and dedoped with potassium ions.

[0051] Examples of carbon materials capable of absorbing and releasing potassium ions include those containing graphite; soft carbon, which is an example of low-crystalline carbon; fullerene; carbon nanomaterials in general; polyacene; carbon black (e.g., ketjen black, acetylene black, channel black, lamp black, oil furnace black, thermal black); hard carbon; and the like.

[0052] Examples of elements that alloy with potassium include Ge, Sn, Pb, In, Zn, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Au, Cd, Hg, Ga, Tl, C, N, Sb, Bi, O, S, Se, Te, and Cl.

[0053] The separators 761, 762 are microporous sheets made of resin. Any known material can be used as the material for the separators 761, 762 as long as it does not impair the performance of the battery. The separators 761, 762 may be made of a woven fabric or nonwoven fabric insoluble in organic solvents, or a synthetic resin microporous film made of a polyolefin resin such as polyethylene. The separators 761, 762 may also be a laminated film formed by laminating a heat-resistant porous layer and a porous film.

[0054] The first electrode assembly 700a is formed by winding a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762. The first electrode assembly 700a is formed by stacking the positive electrode plate 740, the separator 761, the negative electrode plate 750, and the separator 762 in this order and winding them. In this embodiment, the positive electrode plate 740, the negative electrode plate 750, and the separators 761 and 762 are wound around a winding axis L extending in the X-axis direction, thereby forming the wound first electrode assembly 700a. The winding axis L is an imaginary axis that serves as the central axis when winding the positive electrode plate 740, the negative electrode plate 750, and the separators 761 and 762. In this embodiment, the winding axis L is a straight line that passes through the center of the first electrode assembly 700a and is parallel to the X-axis direction.

[0055] A plurality of protruding pieces 743 protruding outward are arranged at intervals on the edge of the positive electrode plate 740 in the negative X-axis direction. Similarly, a plurality of protruding pieces 753 protruding outward are arranged at intervals on the edge of the negative electrode plate 750 in the positive X-axis direction. The plurality of protruding pieces 743 are portions where no positive electrode active material layer is disposed and the positive electrode current collector foil 741 is exposed (positive electrode active material layer non-formed portions). The plurality of protruding pieces 753 are portions where no negative electrode active material layer is disposed and the negative electrode current collector foil 751 is exposed (negative electrode active material layer non-formed portions). In FIG. 4 , the active material layer non-formed portions (positive electrode active material layer non-formed portions, negative electrode active material layer non-formed portions) are indicated by diagonal lines.

[0056] When the positive electrode plate 740, the negative electrode plate 750, and the separators 761, 762 are wound, the multiple protruding pieces 743 of the positive electrode plate 740 substantially overlap at the end face (one end face) of the main body 710 in the negative X-axis direction, and the multiple protruding pieces 753 of the negative electrode plate 750 substantially overlap at the end face (the other end face) in the positive X-axis direction. The portion of the positive electrode plate 740 where the multiple protruding pieces 743 overlap is the positive electrode tab portion 721. In other words, the positive electrode tab portion 721 is a portion where multiple pieces (protruding pieces 743) of the same polarity electrode plates (positive electrode plate 740) among the multiple electrode plates (positive electrode plate 740 and negative electrode plate 750) are stacked. The first terminal current collector 600a is connected (joined) to the positive electrode tab portion 721. Therefore, the first terminal current collector 600a is at a positive electrode potential. In other words, the first terminal current collector 600a is an example of a positive electrode current collector. Furthermore, the first terminal 300a connected to the first terminal current collector 600a has a positive electrode potential and is used as a positive electrode terminal.

[0057] Similarly, the portion of the negative electrode plate 750 where the multiple protruding pieces 753 overlap is the negative electrode tab portion 722. In other words, the negative electrode tab portion 722 is a region where multiple pieces (protruding pieces 753) of the same polarity electrode plate (negative electrode plate 750) among the multiple electrode plates (positive electrode plate 740 and negative electrode plate 750) are stacked. The first housing current collector 650a is connected (joined) to the negative electrode tab portion 722. Therefore, the first housing current collector 650a has a negative electrode potential. In other words, the first housing current collector 650a is an example of a negative electrode current collector. Furthermore, the portion of the lid 120 connected to the first housing current collector 650a is part of the first housing portion 140a, and therefore the first housing portion 140a has a negative electrode potential.

[0058] The shape of the first electrode body 700a is not limited to a wound type, but may be a stack type in which flat electrode plates are stacked, or a shape in which the electrode plates and / or separators are folded accordion-like (a form in which the separator is folded accordion-like to sandwich a rectangular electrode plate, a form in which the electrode plate and separator are stacked and then folded accordion-like, etc.).

[0059] Next, the components corresponding to the second housing portion 140b will be described in detail. As shown in Fig. 3, the components corresponding to the second housing portion 140b are a second terminal 300b, a second terminal current collector 600b, a second housing portion current collector 650b, a second outer gasket 400b, a second inner gasket 500b, and a second electrode body 700b.

[0060] The second terminal 300b is a terminal electrically connected to the second electrode body 700b via the second terminal current collector 600b. The second terminal 300b is made of aluminum or an aluminum alloy. The second terminal 300b is connected (joined) to the second terminal current collector 600b by crimping, welding, or the like, and is attached to the lid 120.

[0061] In the present embodiment, the second terminal 300b has a terminal body 310b and a shaft 320b protruding from the terminal body 310b. The terminal body 310b is a portion that protrudes outward (in the positive direction of the Z axis) from the lid 120. The shaft 320b is inserted into a second through-hole 121b of the lid 120 and penetrates the lid 120. The shaft 320b is connected (joined) to the second terminal current collector 600b by being crimped while passing through the lid 120, the second outer gasket 400b, the second inner gasket 500b, and the second terminal current collector 600b.

[0062] The second terminal current collector 600b is disposed in the second accommodation portion 140b in the positive direction of the X-axis of the second electrode body 700b. The second terminal current collector 600b is connected (joined) to the second electrode body 700b and the second terminal 300b, and is a conductive current collecting member that electrically connects the second electrode body 700b and the second terminal 300b. The second terminal current collector 600b is made of aluminum or an aluminum alloy.

[0063] The second storage unit current collector 650b is disposed in the second storage unit 140b in the negative X-axis direction of the second electrode body 700b. The second storage unit current collector 650b is connected (joined) to the second electrode body 700b and the lid 120 of the container 100, and is a conductive current collecting member that electrically joins the second electrode body 700b and the container 100. The second storage unit current collector 650b is made of aluminum or an aluminum alloy.

[0064] The second outer gasket 400b is a rectangular, plate-shaped insulating seal member disposed between the lid 120 and the second terminal 300b, providing insulation and sealing between the lid 120 and the second terminal 300b. The second inner gasket 500b is a rectangular, plate-shaped insulating seal member disposed between the lid 120 and the second terminal current collector 600b in the second storage section 140b, providing insulation and sealing between the lid 120 and the second terminal current collector 600b. The second outer gasket 400b and the second inner gasket 500b are examples of insulating negative electrode insulators that insulate the second terminal 300b and the second terminal current collector 600b from the container 100. The second outer gasket 400b and the second inner gasket 500b are formed from the same material as the first outer gasket 400a and the first inner gasket 500a.

[0065] The second electrode body 700b has basically the same structure as the first electrode body 700a (see FIG. 4). The second housing current collector 650b is connected (joined) to the positive electrode tab portion 721 of the second electrode body 700b. Therefore, the second housing current collector 650b has a positive electrode potential. In other words, the second housing current collector 650b is an example of a positive electrode current collector. Furthermore, the portion of the lid 120 connected to the second housing current collector 650b is part of the second housing portion 140b, and therefore the second housing portion 140b has a positive electrode potential.

[0066] The second terminal current collector 600b is connected (joined) to the negative electrode tab portion 722 of the second electrode body 700b. Therefore, the second terminal current collector 600b has a negative electrode potential. In other words, the second terminal current collector 600b is an example of a negative electrode current collector. Furthermore, the second terminal 300b connected to the second terminal current collector 600b has a negative electrode potential and is used as a negative electrode terminal.

[0067] Fig. 5 is a cross-sectional view schematically showing the internal configuration of the energy storage unit 10 according to the embodiment. As shown in Fig. 5, as described above, the portion of the lid 120 that is part of the first storage section 140a is at a negative electrode potential, and the portion of the lid 120 that is part of the second storage section 140b is at a positive electrode potential. Therefore, it can be said that the first storage section 140a and the second storage section 140b are electrically connected in series.

[0068] Furthermore, the energy storage device 1 includes a first balancer circuit 190a and a second balancer circuit 190b for each energy storage unit 10. The first balancer circuit 190a and the second balancer circuit 190b are included on the circuit board. The first balancer circuit 190a and the second balancer circuit 190b are balancer circuits that suppress the voltage difference between the first electrode body 700a and the second electrode body 700b by discharging the electrode body with a relatively higher voltage out of the first electrode body 700a and the second electrode body 700b. The first balancer circuit 190a is electrically connected to the first housing portion 140a and the first terminal 300a. The second balancer circuit 190b is electrically connected to the second housing portion 140b and the second terminal 300b. The first balancer circuit 190 a and the second balancer circuit 190 b may cooperate with each other among the power storage units 10 to reduce the difference in the remaining amount of electricity among the power storage units 10 .

[0069] 6 is a perspective view showing the electrical connection structure of two adjacent energy storage units 10 among the plurality of energy storage units 10 according to the embodiment. As shown in FIG. 6 , of the two adjacent energy storage units 10, one energy storage unit 10 is disposed with its second terminal 300b in the positive direction of the X-axis, and the other energy storage unit 10 is disposed with its first terminal 300a in the positive direction of the X-axis. The second terminal 300b of one energy storage unit 10 is at a negative electrode potential, and the first terminal 300a of the other energy storage unit 10 is at a positive electrode potential. The first terminal 300a and the second terminal 300b are electrically connected in series by a bus bar 199. The other adjacent energy storage units 10 are also electrically connected in series by other bus bars (not shown).

[0070] [Explanation of Effects] As described above, according to the embodiment, the first storage portion 140a of the container 100 contains a first electrolyte, and the second storage portion 140b contains a second electrolyte. Here, the first electrolyte and the second electrolyte are potassium ion nonaqueous electrolytes that do not alloy with aluminum. Therefore, the positive electrode current collector foil 741, the negative electrode current collector foil 751, the container 100, the first terminal 300a, and the second terminal 300b can be made of aluminum or an aluminum alloy. Therefore, the amount of copper used in the energy storage unit 10 can be reduced.

[0071] Furthermore, if each collector (first terminal collector 600a, second terminal collector 600b, first storage section collector 650a, second storage section collector 650b) is also formed from aluminum or an aluminum alloy, the amount of copper used in the energy storage unit 10 can be further reduced.

[0072] The container 100 is a monoblock container in which the first container portion 140a and the second container portion 140b are integrated, and therefore can be easily formed by extrusion molding.

[0073] Since the first balancer circuit 190a is connected to the container 100 and the first terminal 300a (positive terminal), and the second balancer circuit 190b is connected to the container 100 and the second terminal 300b (negative terminal), the voltage difference between the first electrode body 700a and the second electrode body 700b can be suppressed, and overcharging of one of the electrode bodies can be prevented.

[0074] Even when the first terminal 300a of one of two adjacent energy storage units 10 and the second terminal 300b of the other energy storage unit 10 are electrically connected in series by a bus bar 199, the amount of copper used is reduced, thereby preventing short circuits caused by copper and improving reliability.

[0075] Here, a prismatic container has a greater effect of suppressing the expansion of the electrode assembly than a pouch-shaped container or a cylindrical container. Furthermore, in the case of a cylindrical container, expansion may be suppressed by integrating it with glass wool or the like, but because the cylindrical container and the glass wool are integrated, disassembly is difficult and recyclability is poor. In contrast, a prismatic container is restrained by a restraining member that is easy to disassemble, thereby suppressing expansion. Separation of the restraining member and the prismatic container is also easy, so recyclability can also be improved. In other words, in this embodiment, the container 100, which is a prismatic container, can enhance the expansion suppression effect on the first electrode assembly 700a and the second electrode assembly 700b while also improving recyclability.

[0076] Here, it is assumed that the energy storage unit 10 is a lithium ion battery. In a lithium ion battery, it is difficult to electrically connect the negative electrode plate 750 of the first electrode body 700a and the positive electrode plate 740 of the second electrode body 700b to the container 100.

[0077] If aluminum or an aluminum alloy is used for the container 100, the container 100 electrically connected to the negative electrode plate 750 of the first electrode body 700a will form an alloy with lithium, resulting in holes in the container 100.

[0078] When stainless steel is used for the container 100, if a segregation layer of the stainless steel is present in the container 100, this segregation layer may form an alloy with lithium, resulting in the formation of a hole in the container 100.

[0079] If the container 100 is made of iron, plated steel, or the like, the container 100 electrically connected to the positive electrode plate 740 of the second electrode body 700b will dissolve due to the positive electrode potential, resulting in holes being formed in the container 100.

[0080] In this embodiment, the first electrolyte and the second electrolyte are potassium ion non-aqueous electrolytes that do not alloy with aluminum, so that the above-described damage to the container 100 can be suppressed.

[0081] (Modifications) Modifications of the above-described embodiment will be described below. In the following description, the same parts as those in the above-described embodiment or other modifications will be denoted by the same reference numerals, and the description thereof may be omitted.

[0082] [Modification 1] In Modification 1, another shape of the container will be described. In the above embodiment, the container 100 has an outer shape of a rectangular parallelepiped, but the container may have any outer shape based on a rectangular parallelepiped.

[0083] 7A and 7B are perspective views showing containers 100c and 100d according to Modification 2. The container 100c shown in FIG. 7A has an outer shape based on a rectangular parallelepiped, with corners facing the negative X-axis direction and the positive Z-axis direction and corners facing the positive X-axis direction and the positive Z-axis direction cut out in rectangular shapes. A first terminal 300a and a first outer gasket 400a are disposed in the cutout 171c of the container 100c facing the negative X-axis direction. Meanwhile, a second terminal 300b and a second outer gasket 400b are disposed in the cutout 171c of the container 100c facing the positive X-axis direction. A container having at least one corner cut out like this rectangular parallelepiped may be included in the category of rectangular containers.

[0084] The container 100d shown in FIG. 7B has a rectangular parallelepiped-like shape with a top surface 172d and a bottom surface 173d that are convexly curved. Specifically, the top surface 172d of the container 100d is a curved surface that protrudes in the positive direction of the Z axis when viewed in the X axis direction. A first terminal 300a is disposed on the top surface 172d via a first outer gasket 400a, and a second terminal 300b is disposed on the top surface 172d via a second outer gasket 400b. The bottom surface 173d of the container 100d is a curved surface that protrudes in the negative direction of the Z axis when viewed in the X axis direction. In this way, a rectangular container may include a container in which at least one surface of the rectangular parallelepiped is a curved surface.

[0085] [Variation 2] In the above embodiment, the first electrolyte in the first storage portion 140a and the second electrolyte in the second storage portion 140b are potassium ion nonaqueous electrolytes. However, at least one of the first electrolyte and the second electrolyte may be a sodium ion nonaqueous electrolyte. Because sodium ion nonaqueous electrolytes do not alloy with aluminum, even in this case, the positive electrode current collector foil 741, the negative electrode current collector foil 751, the container 100, the first terminal 300a, the second terminal 300b, and each current collector can be formed of aluminum or an aluminum alloy. This reduces the amount of copper used in the entire energy storage device 1. Furthermore, it also reduces short circuits caused by copper.

[0086] The sodium ion non-aqueous electrolyte (nonaqueous electrolyte solution) is composed of a non-aqueous solvent and a sodium salt dissolved therein. ６ Examples of the sodium salt include sodium salts such as NaMO. Multiple sodium salts may be used. In this case, any known material can be used as the positive electrode active material for forming the positive electrode active material layer 742 as long as it is capable of absorbing and releasing sodium ions. Specifically, examples of the positive electrode active material include NaMO. ２ Layered oxides such as NaMPO ４ And Na ４ M ３ (P.O. ４ ) P ２ O ７ Polyanionic sodium metalates such as Na ｘ M(CN) ６ and sodium hexacyanometallates such as those mentioned above. Here, "M" is a metal element such as Ti, V, Cr, Fe, Co, Ni, Cu, and Zn. The positive electrode active material is preferably a positive electrode active material that can be doped and dedoped with sodium ions.

[0087] On the other hand, any known material can be used as the negative electrode active material forming the negative electrode active material layer 752 as long as it is capable of absorbing and releasing sodium ions. Specific examples of the negative electrode active material include sodium metal, an alloy capable of absorbing and releasing sodium, and carbon materials (soft carbon, hard carbon). The negative electrode active material is preferably one that can be doped and dedoped with sodium ions.

[0088] Both the first storage section 140a and the second storage section 140b may contain a sodium ion nonaqueous electrolyte, or one may contain a sodium ion nonaqueous electrolyte and the other may contain a potassium ion nonaqueous electrolyte.

[0089] [Modification 3] In the above embodiment, the case where the first balancer circuit 190a is electrically connected to the first accommodation portion 140a and the first terminal 300a, and the second balancer circuit 190b is electrically connected to the second accommodation portion 140b and the second terminal 300b has been exemplified. However, it is sufficient that the first balancer circuit 190a is electrically connected to the container 100 and the first terminal 300a, and the second balancer circuit 190b is electrically connected to the container 100 and the second terminal 300b. Modification 3 describes one example of this.

[0090] 8 is an explanatory diagram showing an example of a connection between the first balancer circuit 190a and the second balancer circuit 190b according to Modification Example 3. As shown in FIG. 8, the first balancer circuit 190a and the second balancer circuit 190b are connected branching off from the lid 120 of the container 100. In this state, the first balancer circuit 190a is connected to the first terminal 300a, and the second balancer circuit 190b is connected to the second terminal 300b. Even in this connection configuration, the voltage difference between the first electrode body 700a and the second electrode body 700b can be reduced, and overcharging of one of the electrode bodies can be prevented.

[0091] The first balancer circuit 190a may be connected to any location on the container 100. The same applies to the second balancer circuit 190b.

[0092] (Others) While the energy storage unit and the like according to the embodiments of the present invention (including its modified examples, the same applies hereinafter) have been described above, the present invention is not limited to the above-described embodiments. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0093] In the above embodiment, the first terminal current collector 600a, the first housing current collector 650a, the second terminal current collector 600b, and the second housing current collector 650b are formed of aluminum or an aluminum alloy. However, at least one of the first terminal current collector 600a, the first housing current collector 650a, the second terminal current collector 600b, and the second housing current collector 650b may be formed of another conductive material.

[0094] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention.

[0095] The present invention can be applied to an electricity storage unit including an electricity storage unit such as a secondary battery.

[0096] REFERENCE SIGNS LIST 1 Energy storage device 10 Energy storage unit 100, 100c, 100d Container 110 Container body 111 Partition wall 120 Lid body 130 Bottom body 140a First storage section 140b Second storage section 190a First balancer circuit 190b Second balancer circuit 199 Bus bar 300a First terminal (positive electrode terminal) 300b Second terminal (negative electrode terminal) 600a First terminal current collector 600b Second terminal current collector 650a First storage section current collector 650b Second storage section current collector 700a First electrode body 700b Second electrode body 710 Body part 721 Positive electrode tab part 722 Negative electrode tab part 740 Positive electrode plate 741 Positive electrode current collector foil 742 Positive electrode active material layer 750 Negative electrode plate 751 Negative electrode current collector foil 752 Negative electrode active material layer

Claims

a first electrode body and a second electrode body, each of which is formed by stacking a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector foil and a negative electrode plate having a negative electrode active material layer formed on a negative electrode current collector foil; a first electrolyte and a second electrolyte each consisting of a potassium ion non-aqueous electrolyte or a sodium ion non-aqueous electrolyte; a container that accommodates the first electrode body, the second electrode body, the first electrolyte, and the second electrolyte; The container comprises: a first storage section that stores the first electrode body and the first electrolyte in a state in which the negative electrode plate of the first electrode body is electrically connected; a second storage section that stores the second electrode body and the second electrolyte in a state where the positive electrode plate of the second electrode body is electrically connected to the second electrode body, the first housing portion is disposed outside the first housing portion in a state insulated from the first housing portion and includes a positive electrode terminal electrically connected to a positive electrode plate of the first electrode body; the second housing portion is disposed outside the second housing portion in a state insulated from the second housing portion, and includes a negative electrode terminal electrically connected to the negative electrode plate of the second electrode body; the positive electrode current collector foil, the negative electrode current collector foil, the container, the positive electrode terminal, and the negative electrode terminal are formed of aluminum or an aluminum alloy; Energy storage unit. 　 The power storage unit according to claim 1; a first balancer circuit connected to the container and the positive terminal; a second balancer circuit connected to the container and the negative terminal; Energy storage device. 　 a plurality of the power storage units are arranged, and of two adjacent power storage units, the positive electrode terminal of one power storage unit and the negative electrode terminal of the other power storage unit are electrically connected in series by a bus bar; The power storage device according to claim 2 .

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