Electric power storage device

Abstract

This electric power storage device comprises an electric power storage element, a holding member that holds the electric power storage element, and an exterior body that accommodates the electric power storage element and the holding member. The interior of the exterior body is provided with a first chamber and a second chamber that are formed by the holding member and the exterior body, and a joining portion in which the holding member and the exterior body are joined to each other. The electric power storage element is disposed in one of the first chamber or the second chamber. The holding member is provided with a through-hole that connects the first chamber and the second chamber.

Description

Power storage device

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

[0002] Patent Document 1 discloses an electricity storage system in which an electricity storage unit, which is formed by assembling a plurality of capacitor cells on a frame and unitizing them, is accommodated in a housing.

[0003] Japanese Patent Application Laid-Open No. 2007-110035

[0004] The space inside the housing is divided by a frame, and if a pressure difference occurs between the two spaces separated by the frame, the pressure difference may damage the storage elements and the like, potentially reducing the reliability of the storage device.

[0005] The present invention was made by the inventors of the present application by focusing on the above-mentioned problem, and aims to provide a power storage device that can suppress a decrease in reliability.

[0006] An energy storage device according to one embodiment of the present invention comprises an energy storage element, a holding member that holds the energy storage element, and an exterior body that houses the energy storage element and the holding member, the interior of the exterior body comprising a first chamber and a second chamber formed by the holding member and the exterior body, and a joint where the holding member and the exterior body are joined to each other, the energy storage element is disposed in one of the first chamber and the second chamber, and the holding member has a through hole that connects the first chamber and the second chamber.

[0007] According to the present invention, it is possible to provide a power storage device capable of suppressing a decrease in reliability.

[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 a first holding member according to an embodiment. FIG. 4 is a perspective view showing a part of the first holding member according to an embodiment, with transparency. FIG. 5 is a perspective view showing a second holding member according to an embodiment. FIG. 6 is a perspective view showing a part of the second holding member according to an embodiment, with transparency. FIG. 7 is a cross-sectional perspective view showing a joining structure between an exterior body and an energy storage unit according to an embodiment. FIG. 8 is a perspective view showing a part of the first holding member according to Modification 1, with transparency. FIG. 9 is a cross-sectional view showing a surrounding structure of a through hole in a first holding member according to Modification 2.

[0009] (1) An energy storage device according to one aspect of the present invention comprises an energy storage element, a holding member that holds the energy storage element, and an exterior body that houses the energy storage element and the holding member, the interior of the exterior body comprising a first chamber and a second chamber formed by the holding member and the exterior body, and a joint where the holding member and the exterior body are joined to each other, the energy storage element is disposed in one of the first chamber and the second chamber, and the holding member has a through hole that connects the first chamber and the second chamber.

[0010] According to the energy storage device described in (1) above, the holding member has a through-hole connecting the first chamber and the second chamber, so that the pressure difference between the first chamber and the second chamber can be suppressed by the through-hole. This suppresses damage to the energy storage element and the joints caused by the pressure difference. Therefore, it is possible to provide an energy storage device that can suppress a decrease in reliability.

[0011] (2) In the energy storage device described in (1) above, the joint may be formed in a continuous ring shape when viewed from the direction in which the holding member and the outer casing overlap, and the through hole may be positioned in a position surrounded by the joint.

[0012] According to the energy storage device described in (2) above, since the joint is formed in a continuous ring shape, the space partitioned by the holding member and the joint is highly sealed. Even in this case, since the through-hole is positioned so as to be surrounded by the joint, the difference in air pressure between the inside and outside of the space can be suppressed.

[0013] (3) The energy storage device described in (1) or (2) above may further include a bus bar electrically connected to the energy storage element, at least a portion of the bus bar being embedded in the holding member, and the through hole passing through the holding member and the bus bar.

[0014] According to the energy storage device described above in (3), at least a portion of the bus bar is embedded and integrated into the holding member, and a through hole is also formed in the bus bar. Therefore, even in the holding member in which the bus bar is insert-molded, the air pressure difference between the first chamber and the second chamber can be suppressed.

[0015] (4) In the energy storage device described in (3) above, the bus bar may include a main body portion that serves as a current path for the energy storage device, and a protrusion portion that protrudes from the main body portion in a direction away from the current path, and the through hole may be arranged in the protrusion portion.

[0016] In the energy storage device described in (4) above, if through holes are formed in the main body portions of the bus bars, the cross-sectional area of ​​the main body portions is reduced, resulting in high resistance. In this aspect, since through holes are formed in the protruding portions of the bus bars, the cross-sectional area of ​​the main body portions can be maintained, thereby preventing high resistance.

[0017] (5) The electricity storage device according to any one of (1) to (4) above may further include a breathable waterproof film covering the through-hole.

[0018] According to the electricity storage device described in (5) above, the breathable waterproof film covering the through-holes can prevent water from entering the first and second chambers while maintaining breathability.

[0019] (Embodiments) Hereinafter, with reference to the drawings, a description will be given of an energy storage device according to an embodiment of the present invention (including modifications thereof). Note that the embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement positions and connection forms shown in the following embodiments are 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 reference numerals are used for identical or similar components. 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.

[0020] In the following description and drawings, the X-axis direction is defined as the arrangement direction of the exterior body and exterior cover in the exterior body of the energy storage device, or the arrangement direction of multiple energy storage elements included in the energy storage device. The Y-axis direction is defined as the protruding direction of each lead terminal of an energy storage element. The Z-axis direction is defined as the arrangement direction of a pair of lead terminals included in an energy storage element, or the up-down direction. The X-axis direction, Y-axis direction, and Z-axis direction intersect with each other (orthogonal in the following embodiments and their modifications). Note that, depending on the usage mode, the Z-axis direction may not be the up-down direction. However, for convenience of explanation, the Z-axis direction will be described as the up-down direction below. In the following description, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. The same applies to the Y-axis direction and the Z-axis direction. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, may also include cases where the directions or attitudes are not strictly those. The phrase "two directions are perpendicular" does not only mean that the two directions are completely perpendicular, but also that they are substantially perpendicular, i.e., that there is a difference of about a few percent. In the following description, the term "insulating" means "electrically insulating." An insulating material has a volume resistivity of 1×10 ６ Ωm or more, more preferably 1×10 ７ Ωm or more, more preferably 1×10 １０ It is preferable that the material be made of a material with a resistance of Ωm or more.

[0021] [General Description of Energy Storage Device] First, a general description of an energy storage device 1 according to an embodiment will be given using Fig. 1 and Fig. 2. Fig. 1 is a perspective view showing the appearance of the energy storage device 1 according to an embodiment. Fig. 2 is an exploded perspective view showing each component of the energy storage device 1 according to an embodiment when disassembled.

[0022] The power storage device 1 is a device capable of charging with electricity from an external source and discharging electricity to an external source. In this embodiment, the power storage device 1 has a rectangular parallelepiped shape. A rectangular parallelepiped is a hexahedron with all sides formed of rectangles or squares. The power storage device 1 is a battery module (battery assembly) used for power storage, power supply, or the like. Specifically, the power storage device 1 is used as a battery for driving or starting the engine of a moving object such as an automobile, motorcycle, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, automatic guided vehicle (AGV), or electric railway vehicle. 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 be used as a stationary battery for home or business use.

[0023] 1 and 2 , the energy storage device 1 includes an energy storage unit 20 and an exterior body 10 that houses the energy storage unit 20. The exterior body 10 includes an exterior body main body 11 that houses the energy storage unit 20, and an exterior body lid 12 that covers the exterior body main body 11.

[0024] The exterior body 10 is a rectangular (box-shaped) container (module case) that constitutes the exterior body of the energy storage device 1. In other words, the exterior body 10 is a member that fixes the energy storage unit 20 and the like in predetermined positions and protects these elements from impacts and the like.

[0025] The exterior body main body 11 is a rectangular cylindrical member with a bottom that is open in the positive direction of the X axis, and the open portion is an opening 111. The opening 111 has a square shape in a plan view (as viewed in the X axis direction). In addition to the energy storage unit 20, the opening 111 of the exterior body main body 11 accommodates a plurality of bus bars (not shown) and fuses (not shown) held by the energy storage unit 20.

[0026] The exterior body lid 12 is a member that closes the opening 111 of the exterior body main body 11 and is joined to the exterior body main body 11 while closing the opening 111 from the positive direction of the X axis. A circuit board 35 is disposed outside the opening 111 at a position corresponding to the exterior body lid 12. That is, the circuit board 35 is housed between the exterior body main body 11 and the exterior body lid 12. The exterior body lid 12 has a pair of external terminals 81 (positive and negative). The external terminals 81 are electrically connected to the multiple energy storage elements 21 included in the energy storage unit 20 via the bus bars, fuses, and circuit board 35. The energy storage device 1 charges with electricity from the outside and discharges electricity to the outside via the external terminals 81. The external terminals 81 are formed of a conductive material made of a metal such as copper, a copper alloy, aluminum, an aluminum alloy, or nickel, or a combination thereof, or a conductive material other than a metal.

[0027] Here, each bus bar is a plate-like member that electrically connects the external terminal 81 and the energy storage element 21. Each bus bar is formed of a conductive member made of metal such as copper, copper alloy, aluminum, aluminum alloy, or nickel, or a combination thereof, or a conductive member other than metal.

[0028] The fuse is a member that protects the circuit board 35, the plurality of energy storage elements 21, etc. from a current exceeding the rated value. When a current exceeding the rated value flows, the fuse melts to interrupt the flow of current.

[0029] The circuit board 35 has multiple electrical components (not shown), and these multiple electrical components form a detection circuit that detects the state (temperature, voltage, current, etc.) of each storage element 21, and a control circuit that controls charging and discharging.

[0030] The exterior body 11 and exterior body lid 12 of the exterior body 10 are formed from insulating materials 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 composite materials thereof, or from metals or the like with an insulating coating. This prevents the energy storage element 21 and the like from coming into contact with external metal members or the like. Note that the exterior body 10 may be formed from a conductive material such as metal as long as the electrical insulation of the energy storage element 21 and the like is maintained. The exterior body 11 and the exterior body lid 12 may be formed from the same material or different materials.

[0031] [Electricity storage unit] The electricity storage unit 20 includes an electricity storage element 21 and a holding member 22. In the present embodiment, an example is shown in which four electricity storage elements 21 are provided, but the number of installed electricity storage elements 21 may be one or more.

[0032] The energy storage element 21 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. In this embodiment, the energy storage element 21 is a pouch-type energy storage element having a flat shape, and a plurality of pouch-type energy storage elements 21 (four in this embodiment) are arranged side by side in the X-axis direction. The energy storage element 21 is not limited to a pouch-type energy storage element, and may be an energy storage element having a flat rectangular parallelepiped (prismatic) shape, a polygonal prism shape other than a rectangular parallelepiped, a cylindrical shape, an elongated cylindrical shape, or an elliptical cylindrical shape, and the size and shape thereof are not limited. The number of energy storage elements 21 arranged is also not particularly limited. The energy storage element 21 is not limited to a nonaqueous electrolyte secondary battery, and may be a secondary battery other than a nonaqueous electrolyte secondary battery, a capacitor, or a battery using a solid electrolyte. The energy storage element 21 may be a primary battery instead of a secondary battery. The plurality of energy storage elements 21 are arranged in the X-axis direction, and adjacent energy storage elements 21 may or may not be joined together with an adhesive or double-sided tape. Details of the energy storage elements 21 will be described later.

[0033] The holding member 22 is a member that holds the multiple energy storage elements 21. The holding member 22 includes a first holding member 23 and a second holding member 24 that holds the multiple energy storage elements 21 together with the first holding member 23. The first holding member 23 and the second holding member 24 are each an example of a holding member. Specifically, the first holding member 23 is arranged in the negative X-axis direction of the multiple energy storage elements 21 and is bonded to the energy storage elements 21 that are located at the ends of the multiple energy storage elements 21 in the negative X-axis direction with an adhesive or double-sided tape. The second holding member 24 is arranged in the positive X-axis direction of the multiple energy storage elements 21 and is bonded to the energy storage elements 21 that are located at the ends of the multiple energy storage elements 21 in the positive X-axis direction with an adhesive or double-sided tape. As a result, the first holding member 23 and the second holding member 24 hold the multiple energy storage elements 21 by sandwiching them in the X-axis direction. Note that at least one of the first holding member 23 and the second holding member 24 does not have to be bonded to the energy storage elements 21. In other words, both the first holding member 23 and the second holding member 24 do not have to be joined to the energy storage device 21 .

[0034] The first holding member 23 and the second holding member 24 are formed of 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 thereof, or a metal with an insulating coating. As a result, the first holding member 23 and the second holding member 24 prevent the plurality of energy storage elements 21 from becoming electrically conductive with external conductive members such as metal members. However, if such conduction is not necessary, the first holding member 23 and the second holding member 24 may be formed of an electrically conductive member such as metal. The first holding member 23 and the second holding member 24 may be formed of the same material or different materials.

[0035] Fig. 3 is a perspective view showing the first holding member 23 according to the embodiment. Fig. 4 is a perspective view showing a part of the first holding member 23 according to the embodiment. Fig. 4 shows a resin member provided in the first holding member 23 in a see-through manner.

[0036] 3 and 4 , the first holding member 23 is a member that supports a bus bar 31, which is one of the plurality of bus bars described above. Here, the bus bar 31 includes a first portion 311 that extends in the Z-axis direction and a second portion 312 that extends in the X-axis positive direction from an end of the first portion 311 in the Z-axis negative direction. The first portion 311 and the second portion 312 form a current path of the energy storage device 1.

[0037] The first holding member 23 is formed by insert-molding the bus bar 31 with the resin member described above. In other words, the first holding member 23 can be said to be an insert-molded body in which a part of the bus bar 31 is embedded in the resin member.

[0038] Specifically, the first holding member 23 includes a flat plate portion 25 that overlaps the energy storage element 21 at the end in the negative X-axis direction, and a bus bar support portion 26 that is disposed in the negative Y-axis direction of the flat plate portion 25. An edge portion 251 is provided on the periphery of the flat plate portion 25, and extends continuously along the entire periphery. The edge portion 251 protrudes from both sides in the X-axis direction relative to the flat plate portion 25 (see FIG. 7). A first groove 252 is formed on the end surface of the edge portion 251 in the negative X-axis direction, and extends continuously along the entire periphery.

[0039] The busbar support portion 26 is provided at the end of the edge portion 251 in the negative Y-axis direction and supports the busbar 31. Specifically, the busbar support portion 26 includes a first support portion 261 extending in the Z-axis direction from the end of the edge portion 251 in the negative Y-axis direction, and a second support portion 262 extending in the positive X-axis direction from the end of the first support portion 261 in the negative Z-axis direction. Most of the first portion 311 of the busbar 31 is embedded in the resin member forming the first support portion 261, and the end of the first portion 311 in the positive Z-axis direction protrudes from the resin member. Two through holes 263 aligned in the Z-axis direction are provided at the end of the first support portion 261 in the negative Z-axis direction. Each through hole 263 penetrates the first support portion 261 in the X-axis direction. Therefore, each through hole 263 also penetrates the first portion 311 of the busbar 31 within the first support portion 261.

[0040] The majority of the second portion 312 of the bus bar 31 is embedded in the resin member that forms the second support portion 262, and the end of the second portion 312 in the positive direction of the X-axis protrudes from the resin member.

[0041] Forming through holes 263 in the first holding member 23 that holds the energy storage elements 21 may reduce the strength of the first holding member 23. On the other hand, forming through holes 263 in the bus bar 31, which is part of the current path, may increase the electrical resistance of the bus bar 31, making it more susceptible to temperature rise. Furthermore, when insert molding is performed to embed at least a portion of the bus bar 31 into the first holding member 23 and integrate it, it is necessary to hold the bus bar 31 in a mold. Therefore, by using the through holes 263 formed in the bus bar 31 to hold the bus bar 31 in a mold and molding it with resin, the through holes 263 can be formed in the first holding member 23 and the bus bar 31. As a result, the bus bar 31 is arranged around the through holes 263 in the first holding member 23, thereby reinforcing the area around the through holes 263 in the first holding member 23. Furthermore, by arranging the first holding member 23 around the through hole 263 of the bus bar 31, even if the bus bar 31 generates heat due to current, the heat is stored in the first holding member 23, thereby suppressing a temperature rise in the bus bar 31. The same can be said for the second holding member 24 and the through hole 273 of the bus bar 32, which will be described later.

[0042] Fig. 5 is a perspective view showing the second holding member 24 according to the embodiment. Fig. 6 is a perspective view showing a part of the second holding member 24 according to the embodiment. Fig. 6 shows a resin member provided in the second holding member 24 in a see-through manner.

[0043] 5 and 6 , the second holding member 24 is a member that supports the bus bar 32, which is one of the bus bars described above, the circuit board 35, and a fuse (not shown). The second holding member 24 is a member formed by insert molding the bus bar 32 with the resin member described above. In other words, the second holding member 24 can be considered an insert-molded body in which a portion of the bus bar 32 is embedded in the resin member.

[0044] Specifically, the second holding member 24 integrally includes a board support portion 27 and a detection line holding portion 28. The board support portion 27 is a portion that overlaps the energy storage element 21 at the end in the positive direction of the X-axis. The board support portion 27 supports a circuit board 35 and includes a surrounding wall 29 that continuously surrounds the entire periphery of the circuit board 35. The surrounding wall 29 is formed on the surface of the board support portion 27 in the positive direction of the X-axis.

[0045] The board support portion 27 supports a bus bar 32 and a fuse. The bus bar 32 is disposed within the end of the board support portion 27 facing in the negative Z-axis direction and extends along the Y-axis direction. Both ends of the bus bar 32 in the Y-axis direction protrude from the resin member that forms the board support portion 27, and the remaining portion is embedded in the resin member. The fuse is disposed outside the surrounding wall 29 on the surface of the board support portion 27 facing in the positive X-axis direction.

[0046] Two through holes 273 aligned in the Y-axis direction are provided in the substrate support portion 27 at a position surrounded by the surrounding wall 29. The two through holes 273 are disposed at positions corresponding to the bus bars 32 and penetrate the substrate support portion 27 in the X-axis direction. Therefore, the bus bars 32 inside the substrate support portion 27 are also penetrated by the through holes 273.

[0047] A detection line holder 28 extends in the negative X-axis direction from the end of the substrate support 27 in the negative Y-axis direction. The detection line holder 28 is a portion that holds a plurality of detection lines 36 (see FIG. 2 ) connected to the circuit board 35 in order to detect the state (temperature, voltage, current, etc.) of each storage element 21.

[0048] [Energy Storage Element] Next, the energy storage element 21 will be described in detail. As shown in Fig. 2, the plurality of energy storage elements 21 have the same basic structure, but their outer shapes are partially different. Specifically, the odd-numbered energy storage elements 21 counting from the negative X-axis direction have partially different outer shapes from the even-numbered energy storage elements 21 counting from the negative X-axis direction. In other words, the odd-numbered energy storage elements 21 have the same outer shape, and the even-numbered energy storage elements 21 have the same outer shape.

[0049] First, a description will be given of the basic structure of the energy storage element 21. The energy storage element 21 has an exterior film 210 and a pair of lead terminals 220 (positive and negative electrodes), and an electrode assembly (not shown), an electrolyte (non-aqueous electrolyte: not shown), and the like are contained inside the exterior film 210. There are no particular restrictions on the type of electrolyte as long as it does not impair the performance of the energy storage element 21, and any known material can be used as appropriate.

[0050] The exterior film 210 is a sheet-like exterior body formed of a laminate film, and contains an electrode assembly, an electrolyte solution, and the like, sealed under reduced pressure. The exterior film 210 is composed of two rectangular laminate films stacked in the X-axis direction. The two laminate films are joined (sealed) by heat welding or the like, sandwiching a pair of lead terminals 220 between them. The two laminate films are joined (sealed) by heat welding or the like at locations that do not correspond to the pair of lead terminals 220. The laminate film is a flexible film composed of multiple layers, including a metal layer such as aluminum and a resin layer such as polypropylene (PP) or polyethylene (PE), and the resin layer is disposed at the welding locations (sealed portions). The exterior film 210 may also be constructed by forming a single laminate film into a bag shape and joining the ends of the laminate film together by heat welding.

[0051] The lead terminals 220 are conductive plate-like members (lead plates) electrically connected to the electrode assembly and are disposed so as to penetrate the exterior film 210 and be exposed therefrom. In this embodiment, a pair of lead terminals 220 aligned in the Z-axis direction are disposed so as to protrude in the negative Y-axis direction from the end of the exterior film 210 in the negative Y-axis direction. Specifically, the positive electrode lead terminal 220 is a lead terminal electrically connected to the positive electrode plate of the electrode assembly, and the negative electrode lead terminal 220 is a lead terminal electrically connected to the negative electrode plate of the electrode assembly. In other words, the lead terminals 220 are metal electrode terminals for guiding electricity stored in the electrode assembly to the external space of the energy storage element 21 and for introducing electricity into the internal space of the energy storage element 21 to store electricity in the electrode assembly. The lead terminals 220 are formed of aluminum, an aluminum alloy, copper, a copper alloy, or the like.

[0052] The electrode assembly is an electricity storage element (power generating element) formed by stacking a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate is a current collector foil made of a metal such as aluminum or an aluminum alloy, on which a positive electrode active material layer is formed. The negative electrode plate is a current collector foil made of a metal such as copper or a copper alloy, on which a negative electrode active material layer is formed. Any known material capable of absorbing and releasing charge-transporting ions can be used as the active material for the positive electrode active material layer and the negative electrode active material layer. The separator can be a microporous resin sheet or nonwoven fabric. In this embodiment, the electrode assembly is formed by stacking electrode plates (positive electrode plates and negative electrode plates) in the X-axis direction. The electrode assembly may be of any shape, such as a wound electrode assembly formed by winding electrode plates (positive electrode plates and negative electrode plates), a stacked electrode assembly formed by stacking multiple flat electrode plates, or a bellows-shaped electrode assembly formed by folding electrode plates in a bellows shape.

[0053] [Joint Structure Between Exterior Body and Energy Storage Unit] Next, a description will be given of the joint structure between the exterior body 10 and the energy storage unit 20. Fig. 7 is a cross-sectional perspective view showing the joint structure between the exterior body 10 and the energy storage unit 20 according to the embodiment. Specifically, Fig. 7 is a cross-sectional perspective view showing a cut surface including line VII-VII in Fig. 1.

[0054] 7 , the first holding member 23 of the energy storage unit 20 is joined to the exterior body main body 11 of the exterior body 10. Specifically, the exterior body main body 11 has a bottom frame 113 that protrudes in the positive direction of the X axis formed on an inner bottom surface 112 that faces the opening 111 in the X axis direction. The bottom frame 113 is provided continuously along the entire periphery of the inner bottom surface 112. The bottom frame 113 is disposed at a predetermined distance in the Z axis direction from the inner surface 11 a of the exterior body main body 11.

[0055] The bottom frame 113 is inserted into the first groove 252 of the first holding member 23 via adhesive 253. In this way, the first groove 252 and the bottom frame 113 are joined by being adhered with the adhesive 253. In other words, the first groove 252, the bottom frame 113, and the adhesive 253 are an example of a joint that joins the first holding member 23 and the exterior body 10 to each other. Here, the case where the first holding member 23 and the exterior body 10 are joined with adhesive 253 has been exemplified, but the first holding member 23 and the exterior body 10 may also be joined by thermal welding. In this case, the thermal welding portion is an example of a joint. This joint is formed in a continuous ring shape when viewed from the direction in which the first holding member 23 and the inner bottom surface 112 of the exterior body main body 11 overlap (the X-axis direction).

[0056] The second holding member 24 of the energy storage unit 20 is joined to the exterior body lid 12 of the exterior body 10. Specifically, the exterior body lid 12 has a lid frame 123 formed on an inner top surface 121 facing the opening 111 in the positive X-axis direction, the lid frame 123 protruding in the negative X-axis direction. The lid frame 123 is continuous in an annular shape within the inner top surface 121. The lid frame 123 is disposed at a predetermined distance in the Z-axis direction from the inner surface 12a of the exterior body lid 12. A second groove 124 is formed by the lid frame 123 and the inner surface 12a of the exterior body lid 12. The tip end (the end in the positive X-axis direction) of the surrounding wall 29 of the second holding member 24 is inserted into the second groove 124 via adhesive 243. In this manner, the surrounding wall 29 of the second holding member 24 is joined by being adhered to the second groove 124 of the exterior body lid 12 by the adhesive 243 along its entire periphery. In other words, the surrounding wall 29, the second groove 124, and the adhesive 243 are an example of a joint that joins the second holding member 24 and the exterior body 10 to each other. Here, the case where the second holding member 24 and the exterior body 10 are joined using the adhesive 243 has been exemplified, but the second holding member 24 and the exterior body 10 may also be joined by thermal welding. In this case, the thermal welding portion is an example of a joint. This joint is formed in a continuous ring shape when viewed from the direction in which the second holding member 24 and the inner top surface 121 of the exterior body lid 12 overlap (the X-axis direction).

[0057] In this way, in the energy storage unit 20, the first holding member 23 is joined to the exterior body main body 11 and the second holding member 24 is joined to the exterior body lid 12, so that three major spaces are formed within the exterior body 10. Specifically, these spaces are a first end space 14 defined by the first holding member 23 and the inner bottom surface 112 of the exterior body main body 11, a second end space 15 defined by the second holding member 24 and the inner top surface 121 of the exterior body lid 12, and an intermediate space 16 defined by the first holding member 23 and the second holding member 24. A plurality of energy storage elements 21 are arranged in the intermediate space 16.

[0058] Here, when the first holding member 23 is used as a reference, the first end space 14 is an example of a first chamber, and the intermediate space 16 is an example of a second chamber. The first end space 14 and the intermediate space 16 are connected by the through holes 263 of the first holding member 23. Even if the energy storage elements 21 in the intermediate space 16 expand and the internal pressure of the intermediate space 16 increases, the through holes 263 suppress the air pressure difference between the first end space 14 and the intermediate space 16. Furthermore, even if the energy storage device 1 is used under an air pressure lower or higher than the internal pressure of the first end space 14 and the first end space 14 expands or contracts, the through holes 263 suppress the air pressure difference between the first end space 14 and the intermediate space 16. Therefore, damage to the energy storage elements 21 or the joints (the first groove 252, the bottom frame 113, and the adhesive 253) caused by the air pressure difference can be suppressed. In particular, if the joints (first groove 252, bottom frame 113, and adhesive 253) are damaged, the force of the first holding member 23 to hold the energy storage element 21 decreases. As a result, when the energy storage device 1 vibrates, the energy storage element 21 is more likely to move inside the energy storage device 1. As a result, there is a problem that short circuits are more likely to occur inside and outside the energy storage element 21. Therefore, by connecting the first end space 14 and the intermediate space 16 by each through hole 263 of the first holding member 23, short circuits inside and outside the energy storage element 21 can be suppressed.

[0059] On the other hand, when the second holding member 24 is used as a reference, the second end space 15 is an example of a first chamber, and the intermediate space 16 is an example of a second chamber. The second end space 15 and the intermediate space 16 are connected by the through holes 273 of the second holding member 24. Even if the energy storage elements 21 in the intermediate space 16 expand and the internal pressure of the intermediate space 16 increases, the through holes 273 suppress the air pressure difference between the second end space 15 and the intermediate space 16. Here, the through holes 273 are located at positions surrounded by the surrounding wall 29 of the substrate support portion 27, i.e., at positions surrounded by the joint portion. Therefore, even in the highly sealed space of the second end space 15 surrounded by the surrounding wall 29, the air pressure difference can be suppressed by the through holes 273. Furthermore, even if the energy storage device 1 is used under an air pressure lower or higher than the internal pressure of the second end space 15 and the second end space 15 expands or contracts, the air pressure difference between the second end space 15 and the intermediate space 16 is suppressed by the through holes 273. Therefore, damage to the energy storage elements 21 or the joints (surrounding wall 29, second groove 124, and adhesive 243) caused by the air pressure difference can be suppressed. In particular, if the joints (surrounding wall 29, second groove 124, and adhesive 243) are damaged, the force of the second holding member 24 to hold the energy storage elements 21 will decrease. As a result, when the energy storage device 1 vibrates, the energy storage elements 21 will be more likely to move inside the energy storage device 1. As a result, there is a problem in that short circuits will be more likely to occur inside and outside the energy storage elements 21. Therefore, by connecting the second end space 15 and the intermediate space 16 via each of the through holes 273 in the second holding member 24, short circuits inside and outside the energy storage elements 21 can be suppressed.

[0060] Furthermore, in terms of the vibration direction, when the energy storage device 1 vibrates in the X-axis direction, a force is applied from the energy storage element 21 in the intermediate space 16 to the portion of the first holding member 23 or the second holding member 24 that faces the energy storage element 21 in the X-axis direction (the flat plate portion 25 or the substrate support portion 27). As a result, the first holding member 23 or the second holding member 24 may deform toward the opposite side of the intermediate space 16 in the X-axis direction. In other words, the force of the first holding member 23 or the second holding member 24 to hold the energy storage element 21 in the X-axis direction may decrease. Therefore, by providing a joint in the negative X-axis direction relative to the flat plate portion 25 or the positive X-axis direction relative to the substrate support portion 27, deformation of the first holding member 23 or the second holding member 24 in the X-axis direction can be suppressed. Therefore, a decrease in the force of the first holding member 23 or the second holding member 24 to hold the energy storage element 21 can be suppressed.

[0061] [Effects, etc.] As described above, according to the present embodiment, the first holding member 23 has the through-hole 263 connecting the first end space 14 (first chamber) and the intermediate space 16 (second chamber), so the pressure difference between the first end space 14 and the intermediate space 16 can be suppressed by the through-hole 263. Furthermore, the second holding member 24 has the through-hole 273 connecting the second end space 15 (first chamber) and the intermediate space 16 (second chamber), so the pressure difference between the second end space 15 and the intermediate space 16 can be suppressed by the through-hole 273. As a result, damage to the energy storage elements 21 and joints caused by the pressure difference can be suppressed. Therefore, it is possible to provide an energy storage device 1 that can suppress a decrease in reliability.

[0062] Because the joint portion (surrounding wall 29, second groove 124, and adhesive 243) on the second holding member 24 side is formed in a continuous ring shape, the space partitioned by the second holding member 24 and the joint portion is highly airtight. Even in such a case, because the through hole 273 is positioned in a position surrounded by the joint portion, the air pressure difference between the second end space 15 and the intermediate space 16 can be suppressed.

[0063] At least a portion of the bus bar 31 is embedded in and integrated with the first holding member 23, and a through hole 263 is also formed in the bus bar 31. Therefore, even in the first holding member 23 in which the bus bar 31 is insert-molded, the air pressure difference between the first end space 14 and the intermediate space 16 can be suppressed.

[0064] Similarly, at least a portion of the bus bar 32 is embedded and integrated into the second retaining member 24, and a through hole 273 is also formed in the bus bar 32, so that even in the second retaining member 24 in which the bus bar 32 is insert-molded, the air pressure difference between the second end space 15 and the intermediate space 16 can be suppressed.

[0065] [Explanation of 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.

[0066] (Modification 1) In Modification 1, a case will be described in which a through hole is also arranged in a position surrounded by a joint portion in the first holding member. Fig. 8 is a perspective view showing a part of a first holding member 23a according to Modification 1 in a see-through manner. Fig. 8 is a view corresponding to Fig. 4.

[0067] 8, no through-holes are formed in the first support portion 261a of the first holding member 23a and the first portion 311a of the bus bar 31a. Specifically, the bus bar 31a includes a main body portion 33a that serves as a current path for the energy storage device 1, and a protrusion portion 34a that protrudes from the main body portion 33a in a direction away from the current path.

[0068] The main body 33a includes a first portion 311a and a second portion 312a. The protrusion 34a protrudes in the positive Y-axis direction from the end of the first portion 311a in the negative Z-axis direction, thereby protruding in a direction away from the current path. The tip of the protrusion 34a is located in a position surrounded by the first groove 252a of the first holding member 23a. A through-hole 264a is formed in the tip of the protrusion 34a, penetrating the flat plate portion 25a in the X-axis direction. Therefore, the through-hole 264a is located in a position surrounded by the first groove 252a.

[0069] In this way, the through hole 264a is arranged at a position surrounded by the joint (first groove 252a, bottom frame 113 and adhesive 253) on the first retaining member 23a side, so that the difference in air pressure between the inside and outside of the space partitioned by this joint can be suppressed.

[0070] If a through hole were formed in the main body 33a of the busbar 31a, the cross-sectional area of ​​the main body would be reduced, resulting in high resistance. In this modification, the through hole 264a is formed in the protruding portion 34a of the busbar 31a, thereby maintaining the cross-sectional area of ​​the main body 33a and preventing high resistance. Furthermore, by providing the protruding portion 34a that protrudes from the main body 33a in a direction away from the current path, even if the busbar 31a generates heat due to current, the heat is stored in the protruding portion 34a, thereby preventing a temperature rise in the busbar 31a.

[0071] (Variation 2) In Variation 2, a case where the through hole is covered with a breathable waterproof membrane will be described. Here, the through hole of the first holding member will be described as an example, but the same applies to the through hole of the second holding member.

[0072] 9 is a cross-sectional view showing the structure surrounding the through hole 263b of the first holding member 23b according to Modification 2. As shown in FIG. 9, a breathable waterproof membrane 50b covering the through hole 263b is laminated on the surface of the bus bar 31b facing the negative X-axis direction. Specifically, the breathable waterproof membrane 50b has sufficient breathability to achieve pressure equilibrium between the first end space 14 and the intermediate space 16. The breathability of the breathable waterproof membrane 50b can be measured in accordance with the "air resistance" specified in JIS P8117:2009.

[0073] More specifically, the breathable waterproof membrane 50b is a member made of a waterproof and breathable material. Examples of materials that can be used to form the breathable waterproof membrane 50b include Gore-Tex (registered trademark) and TEMISH (registered trademark). This allows the breathable waterproof membrane 50b to maintain the breathability of the through-hole 263b while also maintaining waterproofness. The breathable waterproof membrane 50b may be installed in any location that covers the through-hole 263b. Other possible locations include the surface of the bus bar 31b facing the positive direction of the X-axis and at least one of both surfaces of the first support portion 261b in the X-axis direction. If the first end space 14 and the intermediate space 16 are connected by the through-hole 263b, for example, there is a risk that the electrolyte in the energy storage element 21 will leak and infiltrate from the intermediate space 16 into the first end space 14. This could adversely affect components disposed in the first end space 14. Therefore, by arranging the breathable waterproof membrane 50b so as to cover the through-hole 263b, it is possible to suppress the pressure difference between the first end space 14 and the intermediate space 16 while suppressing other adverse effects.

[0074] (Others) While the energy storage device 1 according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. In other words, the embodiment disclosed herein is illustrative in all respects and is not restrictive, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0075] In the above embodiment, the exterior film 210 has a rectangular shape when viewed from the X-axis direction, but the exterior film 210 may have any shape. Other shapes of the exterior film 210 include polygonal shapes other than rectangular, oval shapes, elliptical shapes, and circular shapes.

[0076] In the above embodiment, the joint is formed in a continuous ring shape, but the joint may be formed in an intermittent ring shape, or may not be formed in a ring shape.

[0077] In the above embodiment, the case where the through-hole 263 of the first holding member 23 passes through the bus bar 31 has been exemplified, but the through-hole may be provided in a position that does not correspond to the bus bar. The same applies to the second holding member.

[0078] In the above embodiment, the case where two holding members, the first holding member 23 and the second holding member 24, are arranged inside the exterior body 10 has been exemplified, but any number of holding members may be provided as long as it is one or more. It is sufficient that a through hole is formed in at least one of the first holding member 23 and the second holding member 24.

[0079] In the above embodiment, an example is given of a pair of lead terminals 220 protruding from the first side 214 of the exterior film 210, but one of the pair of lead terminals 220 may protrude from the first side 214 of the exterior film 210, and the other lead terminal 220 may protrude from a side other than the first side 214 of the exterior film 210.

[0080] Any combination of the components included in the embodiments and their modifications is also included within the scope of the present invention.

[0081] The present invention can be applied to an electricity storage device or the like that includes an electricity storage element such as a lithium ion secondary battery.

[0082] DESCRIPTION OF SYMBOLS 1 Energy storage device 10 Exterior body 11 Exterior body main body 12 Exterior body cover 14 First end space (first chamber) 15 Second end space (first chamber) 16 Intermediate space (second chamber) 20 Energy storage unit 21 Energy storage element 22 Holding member 23, 23a, 23b First holding member 24 Second holding member 25, 25a Flat plate portion 26 Bus bar support portion 27 Board support portion 28 Detection line holding portion 29 Surrounding wall (joint portion) 31, 31a, 31b, 32, 32a Bus bar 33a Main body portion 34a Protrusion 50b Breathable waterproof membrane 113 Bottom frame (joint portion) 124 Second groove (joint portion) 243, 253 Adhesive (joint portion) 251 Edge portion 252, 252a First groove (joint part) 261, 261a, 261b First support part 262 Second support part 263, 263b, 264a, 273 Through hole 311, 311a First part 312, 312a Second part

Claims

1. An energy storage device comprising: an energy storage element; a holding member that holds the energy storage element; and an exterior body that houses the energy storage element and the holding member, wherein the interior of the exterior body comprises: a first chamber and a second chamber formed by the holding member and the exterior body; and a joint where the holding member and the exterior body are joined to each other, the energy storage element is disposed in one of the first chamber and the second chamber, and the holding member is provided with a through hole that connects the first chamber and the second chamber.

2. The energy storage device according to claim 1, wherein the joint is formed in a continuous ring shape when viewed from the direction in which the holding member and the exterior body overlap, and the through hole is positioned in a position surrounded by the joint.

3. The energy storage device according to claim 1 or 2, further comprising a bus bar electrically connected to the energy storage element, wherein at least a portion of the bus bar is embedded in the holding member, and the through hole passes through the holding member and the bus bar.

4. The energy storage device according to claim 3, wherein the bus bar comprises a main body portion that forms a current path for the energy storage device, and a protrusion portion that protrudes from the main body portion in a direction away from the current path, and the through hole is disposed in the protrusion portion.

5. The electricity storage device according to claim 1 or 2, further comprising a breathable waterproof membrane covering the through-hole.

Images