Power storage element and power storage device

Abstract

Disclosed is a power storage element which comprises: an electrode body in which electrode plates are stacked; a container which houses the electrode body; and a terminal which is provided on the outer surface of the container and is electrically connected to the electrode body. The container has a shape based on a rectangular parallelepiped, and if the shape of the rectangular parallelepiped has a width (L), a height (H), and a thickness (T), the container satisfies the relationship of L > H > T. At least one of the four corners of a long side surface, which are composed of the sides in the width and the height directions, is a first cut part that is cut in a chamfered, triangular prism shape in the thickness direction of the rectangular parallelepiped, and the surface of the first cut part is provided with a gas discharge valve.

Description

Energy storage element and energy storage device

[0001] The present invention relates to an energy storage element and an energy storage device.

[0002] Patent Document 1 discloses a rectangular parallelepiped battery cell having a safety valve formed on one of its outer peripheral surfaces. In a battery system including such a battery cell, it is known that a gas exhaust duct for releasing gas discharged from the safety valve to the outside is disposed so as to protrude from the one outer peripheral surface of the battery cell.

[0003] JP 2009-170258 A

[0004] In recent years, there has been a demand for electricity storage devices to have simpler and less costly gas discharge structures to accommodate gas discharge from safety valves in electricity storage elements, and to improve the volumetric energy density of electricity storage devices including gas discharge mechanisms.

[0005] Therefore, an object of the present invention is to provide an electricity storage element that allows for a space-saving gas discharge structure, and to achieve a high energy density for an electricity storage device using the same.

[0006] A storage element according to one aspect of the present invention comprises an electrode assembly formed by stacking electrode plates, a container for accommodating the electrode assembly, and a terminal installed on the outer surface of the container and electrically connected to the electrode assembly, wherein the container is shaped based on a rectangular parallelepiped, and when the rectangular parallelepiped shape has width (L), height (H), and thickness (T), the relationship is L>H>T, and at least one of the four corners of the long side formed by the sides in the width direction (longitudinal direction) and height direction (vertical direction) is chamfered in the thickness direction of the rectangular parallelepiped and is a first notch cut out in the shape of a triangular prism, and a gas exhaust valve is provided on the surface of the first notch.

[0007] Furthermore, in a storage device using this storage element, when a group of storage elements is housed within the storage device, a triangular prism-shaped space with a series of cutouts can be formed between the inner surface of the outer casing and the group of storage elements.By using this space as a gas exhaust introduction path, it is possible to eliminate the gas exhaust structure that was separately required in conventional storage devices, and to improve the volumetric energy density of the storage device.

[0008] According to the present invention, it is possible to provide an electric storage element that allows for space-saving gas discharge structures, and an electric storage device with high energy density that uses the electric storage element.

[0009] 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 the appearance of an energy storage element according to an embodiment. FIG. 4 is an exploded perspective view showing each component of an energy storage element according to an embodiment when disassembled. FIG. 5 is an exploded perspective view of a container body according to an embodiment. FIG. 6 is an explanatory view for comparing the weld length of the container body according to the embodiment with the weld length of a comparative example. FIG. 7 is a perspective view showing a state in the middle of manufacturing an electrode body according to an embodiment. FIG. 8 is an explanatory view showing a gas flow path according to an embodiment. FIG. 9 is an explanatory view showing a state in which the electrode body is housed in a container according to an embodiment. FIG. 10 is a perspective view showing an energy storage element according to Modification 1. FIG. 11 is a perspective view showing an energy storage element according to Modification 2. FIG. 12 is a perspective view showing an energy storage element according to Modification 3.

[0010] (1) A storage element according to one aspect of the present invention comprises an electrode assembly formed by stacking electrode plates, a container for accommodating the electrode assembly, and a terminal installed on the outer surface of the container and electrically connected to the electrode assembly, wherein the container has a shape based on a rectangular parallelepiped, and when the shape of the rectangular parallelepiped has width (L), height (H), and thickness (T), the relationship is L>H>T, and at least one of the four corners of the long side formed by the sides in the width and height directions is chamfered in the thickness direction of the rectangular parallelepiped and is a first notch cut out in the shape of a triangular prism, and a gas exhaust valve is provided on the surface of the first notch.

[0011] According to the energy storage element described in (1) above, a first notch that is chamfered in the thickness direction of the rectangular parallelepiped is provided at the corner of the container of the energy storage element. When the energy storage element is housed in the exterior body of the energy storage device, the first notch forms a triangular prism-shaped space between the container and the exterior body. A gas discharge valve is provided in the first notch of the energy storage device. When the valve is open, gas is discharged from the gas discharge valve into the space, and this space can be used as a flow path for exhaust gas. In other words, the space can be used more effectively than in the conventional case where a separate gas flow path is provided. Therefore, an energy storage element that allows for space-saving gas discharge structures can be provided.

[0012] (2) In the energy storage element described in (1) above, a second notch may be formed at two corners of the long side surface of the container other than the first notch, the second notch being chamfered in the thickness direction of the rectangular parallelepiped and cut into a triangular prism shape, and the terminal may be arranged in the second notch.

[0013] According to the energy storage element described in (2) above, since the terminal is provided in the second notch, the welding length during container manufacturing can be shortened. This can improve the manufacturing efficiency of the energy storage element. Furthermore, by providing the terminal in the second notch, it is possible to store at least a portion of the terminal and bus bar in the triangular prism-shaped space, thereby reducing the excess space between the lid of the energy storage device and the top of the energy storage element. This can improve the volumetric energy density of the energy storage device.

[0014] (3) In the energy storage element described in (1) above, the container may have a first side surface adjacent to the first notch in the height direction, and a second side surface facing the first side surface across the long side surface, and the terminals may be arranged on each of the first side surface and the second side surface.

[0015] According to the energy storage element described in (3) above, even when terminals are arranged on each of the first side surface and the second side surface, a gas exhaust valve is provided on the surface of the first notch, so that when an energy storage device is constructed using the energy storage element, the volumetric energy density of the energy storage device can be improved compared to when a separate gas flow path is provided.

[0016] (4) In the energy storage device described in any one of (1) to (3) above, the container may have a pair of curved wall portions on the upper and lower surfaces that connect a pair of long sides of the container.

[0017] According to the energy storage element described in (4) above, the upper and lower surfaces of the container are a pair of curved wall portions, and a gas exhaust valve is provided on the surface of the first notch, thereby enabling more effective use of space than when a separate gas flow path is provided. Furthermore, when a wound body having a winding axis in the longitudinal direction of a rectangular parallelepiped is used as the electrode body, the flat portion of the electrode body abuts on the inner wall of the flat portion of the container, and the curved portion of the electrode body abuts on the curved wall portion of the container, respectively. This makes it possible to apply uniform pressure to the electrode body from the container, and prevents deformation of the electrode body due to charging and discharging.

[0018] (5) In the energy storage element described in any one of (1) to (4) above, the electrode body may be chamfered at locations facing the first notch and the second notch of the container.

[0019] According to the energy storage element described in (5) above, the electrode body is also chamfered at the portions facing the first notch and the second notch, which prevents excess space from being generated due to the dimensional difference between the shape of the container and the shape of the electrode body, thereby making it possible to maximize the size of the active material forming portion of the electrode body and thereby increasing the charge / discharge capacity of the energy storage element.

[0020] (6) In a power storage device according to one aspect of the present invention, a plurality of the power storage elements according to any one of (1) to (5) above are stacked so that the first notched portions are continuous with each other.

[0021] According to the energy storage device described in (6) above, a triangular prism-shaped space can be formed in which the first missing portions of the plurality of energy storage elements are continuous in the stacking direction. Therefore, by using this space as a gas exhaust introduction path, the gas exhaust structure required in conventional energy storage devices can be eliminated. This makes it possible to reduce the size of the energy storage device, thereby improving the volumetric energy density of the energy storage device.

[0022] (Embodiments) Hereinafter, with reference to the drawings, an energy storage element according to an embodiment of the present invention (including its modified examples) will be described. 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 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 each component (each component) in this embodiment are those used in this embodiment and may differ from the names of each component (each component) in the background art.

[0023] In the following description and drawings, the longitudinal direction of the energy storage element, or the direction along the winding axis of the electrode body provided in the energy storage element, is defined as the X-axis direction. The thickness direction of the container of the energy storage element is defined as the Y-axis direction. The direction in which the bottom surface of the container body and the top surface of the lid of the container are aligned, or the up-down direction, is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect with each other (orthogonal in this embodiment). Note that, 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 is the up-down direction. In the following description, the term "insulation" 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.

[0024] 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.

[0025] [Description of the Energy Storage Device] First, a schematic configuration of an energy storage device 1 according to the present embodiment will be described. Fig. 1 is a perspective view showing the appearance of the energy storage device 1 according to the embodiment. Fig. 2 is an exploded perspective view showing each component of the energy storage device 1 according to the embodiment.

[0026] 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.

[0027] 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 elements 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 (positive electrode external terminals and negative electrode external terminals) for electrically connecting to an external device, but these are not shown or described here. In addition to the above components, the energy storage device 1 may also include restraining members (end plates, side plates, etc.) that restrain the plurality of energy storage elements 10, bus bar holders that hold the bus bars, bus bar covers, circuit boards that monitor or control the charge and discharge states of the energy storage elements 10, and electrical components such as relays, fuses, shunt resistors, and connectors.

[0028] The exterior body 2 is a substantially rectangular parallelepiped (box-shaped) container (module case or pack case) that constitutes the exterior body (housing, outer shell) of the energy storage device 1. The exterior body 2 houses the plurality of energy storage elements 10 and the plurality of spacers 20, etc., and fixes the plurality of energy storage elements 10 and the plurality of spacers 20, etc., in predetermined positions to protect them from impacts and the like. The exterior body also compresses the plurality of energy storage elements 10 from the outside, thereby suppressing expansion and deformation of the energy storage elements 10. The exterior body 2 is a metal exterior body formed from a metal member such as aluminum, aluminum alloy, stainless steel, iron, or plated steel sheet. The exterior body 2 may be formed from 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 from a conductive material, the inner surface of the exterior body 2 may be coated with an insulating material to ensure insulation between the energy storage elements 10 and the exterior body 2.

[0029] As shown in Fig. 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 bottomed rectangular cylindrical housing (chassis) with an opening 31 formed in the positive direction of the Z axis, and accommodates a plurality of energy storage elements 10, a plurality of spacers 20, and the like. While Fig. 2 shows a case where only one row of energy storage elements 10 is accommodated in the exterior body main body 30, the present invention is not limited to this, and it is also possible to accommodate a plurality of rows of energy storage elements 10 in the exterior body main body 30. Furthermore, in order to prevent interference between the rows of energy storage elements 10, partition plates may be provided between the rows of energy storage elements 10.

[0030] Specifically, the exterior body main body 30 has a bottom wall 32 and a side wall 33. The bottom wall 32 is a flat, rectangular portion of the bottom of the exterior body main body 30 in the negative Z-axis direction. The side wall 33 is a rectangular, annular wall extending from the outer periphery of the bottom wall 32 in the positive Z-axis direction and is provided continuously around the entire circumference of the bottom wall 32. The opening 31 is located inside the side wall 33. A pair of exhaust ports 37 is provided in the portion of the side wall 33 in the negative Z-axis direction. Of the pair of exhaust ports 37, one exhaust port 37 is located at a corner of a side surface parallel to the XZ plane in the negative Z-axis direction and the negative X-axis direction, and the other exhaust port 37 is located at a corner of a side surface parallel to the XZ plane in the negative Z-axis direction and the positive X-axis direction. Each exhaust port 37 connects the inside and outside of the exterior body 2 and serves as a gas exhaust path for exhausting gas discharged from the energy storage device 10 to the outside of the exterior body 2. Here, Figure 2 shows an example in which the exhaust ports 37 of the storage device 1 are provided at both the corners of the long side surfaces facing the negative Z-axis and negative X-axis directions and the corners of the long side surfaces facing the negative Z-axis and positive X-axis directions, but the positions and number of exhaust ports 37 can be changed depending on the number and positions of the safety valves of the storage elements.

[0031] 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 hermetically sealed by being joined by welding, fusing, screwing, etc. The exterior body main body 30 and the exterior body lid 40 may be formed from members of the same material or from members of different materials.

[0032] The energy storage element 10 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. A plurality of energy storage elements 10 are stacked in the Y-axis direction within the exterior body 2. The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. Furthermore, the energy storage element 10 may be an all-solid-state lithium battery using a solid electrolyte, or a polymer lithium battery. Details of the energy storage element 10 will be described later.

[0033] The spacer 20 is an insulating plate or a heat insulating plate that is disposed adjacent to the energy storage element 10 in the positive or negative Y-axis direction of the energy storage element 10, and that insulates and / or heats the energy storage elements 10 from each other or from the exterior housing 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 heat insulating material such as mica.

[0034] Of the spacers 20, the spacers 20 arranged between adjacent energy storage elements 10 are intermediate spacers, and the two spacers 20 arranged at the ends of the energy storage elements 10 in the Y-axis direction are end spacers. All of 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 have a shape that corresponds to the outer shape of the container 100 of the energy storage elements 10. In other words, the spacer 20 is a rectangular parallelepiped that is elongated in the X-axis direction and flat in the XZ plane. In the case of the structure shown in FIG. 2 , the spacer 20 has a shape in which triangular prism-shaped notches 21 are formed at the bottom of both ends in the X-axis direction, which are in the negative Z-axis direction of the energy storage elements 10.

[0035] The bus bar is connected (joined) to the terminals 300 of the plurality of energy storage elements 10. Specifically, the plurality of bus bars are connected to the terminals 300 of the plurality of energy storage elements 10, and are electrically connected to the terminals 300 of the end energy storage elements 10 and to external terminals of the energy storage device 1. The connection form of the bus bar is not particularly limited, and the plurality of energy storage elements 10 may be connected in series or in parallel in any combination, or all of the energy storage elements 10 may be connected in series or in parallel. The bus bar and the terminal 300 are connected (joined) by welding or the like, but the connection form is not particularly limited. The bus bar is formed of a conductive member made of a metal such as aluminum, an aluminum alloy, copper, a copper alloy, or nickel, or a combination thereof, or a conductive member other than a metal.

[0036] [Energy Storage Element] Next, a schematic configuration of the energy storage element 10 according to the present embodiment will be described. Fig. 3 is a perspective view showing the appearance of the energy storage element 10 according to the embodiment. Fig. 4 is an exploded perspective view showing each component of the energy storage element 10 according to the embodiment.

[0037] The energy storage element 10 has a shape in which the length in the X-axis direction is longer than the Y-axis direction and the length in the X-axis direction is longer than the Z-axis direction. In particular, in this embodiment, the energy storage element 10 has a shape in which the length in the Z-axis direction is longer than the Y-axis direction. The energy storage element 10 includes a container 100, a pair of terminals 300 (positive electrode terminal 301, negative electrode terminal 302), and a pair of external gaskets 400. The container 100 accommodates a pair of internal gaskets 500, a pair of current collectors 600 (positive electrode current collector 601, negative electrode current collector 602), and an electrode assembly 700.

[0038] Here, when viewed from the negative Y-axis direction, a chamfered first notch 111 is formed at the corner of the long side surface 130 of the energy storage element 10 facing in the negative Z-axis direction and the positive X-axis direction. This first notch 111 continues to the long side surface 130 on the opposite side of the long side surface 130. When the opposite long side surface 130 is viewed from the positive Y-axis direction, the first notch 111 is formed at the corner of the long side surface 130 facing in the negative Z-axis direction and the positive X-axis direction, and continues to an inclined surface 112. A gas release valve 800 is provided on the inclined surface 112.

[0039] Similarly, when viewed from the negative Y-axis direction, a chamfered first notch 121 is formed at the corner of the long side surface 130 facing the negative Z-axis direction and the negative X-axis direction. This first notch 121 continues to the long side surface 130 on the opposite side of the long side surface 130, and this first notch 121 is formed at the corner of the opposite long side surface 130 facing the negative Z-axis direction and the negative X-axis direction, continuing to an inclined surface 122. A gas release valve 800 can also be provided on the inclined surface 122.

[0040] The components of the positive electrode (terminal 300, external gasket 400, internal gasket 500, current collector 600, etc.; the same applies below) are arranged in a first side region 110 in the positive direction of the X axis of the container 100 (here, the first side region 110 refers to the region in the positive direction of the X axis from an imaginary line extending from the boundary between the inclined surface 112 and the bottom surface 150 to the top surface 140 in the positive direction of the Z axis). In other words, the first side region 110a is the range from the end face of the container 100 in the positive direction of the X axis in which the components of the positive electrode are arranged. The first side region 110 is a portion in the X axis direction that is within a range of 1% to 15% of the length of the container 100 from the end face of the container 100 in the positive direction of the X axis.

[0041] The components of the negative electrode are arranged in a second side surface region 120 in the negative X-axis direction of the container 100 (here, the second side surface region 120 is a region in the negative X-axis direction from an imaginary line extending from the boundary between the inclined surface 122 and the bottom surface 150 to the top surface 140 in the positive Z-axis direction). In other words, the second side surface region 120 is the range from the end surface of the container 100 in the negative X-axis direction where the components of the negative electrode are arranged. The second side surface region 120 is a portion in the X-axis direction that is within a range of 1% to 15% of the length of the container 100 from the end surface of the container 100 in the negative X-axis direction.

[0042] An electrolyte solution (non-aqueous electrolyte) is sealed inside the container 100, but is not shown in the figure. There are no particular restrictions on the type of electrolyte solution, and various types can be selected as long as they do not impair the performance of the energy storage element 10. In addition to the above components, spacers arranged on the sides, above, or below the electrode assembly 700, an insulating film that wraps around the electrode assembly 700, etc. may also be arranged.

[0043] The container 100 is a case having an outer shape based on a rectangular parallelepiped that is long and flat in the X-axis direction. The rectangular parallelepiped that serves as the base for the container 100 has a width (L: length in the X-axis direction), height (H: length in the Z-axis direction), and thickness (T: length in the Y-axis direction) such that L > H > T. The width of the container 100 is at least three times its height. In FIG. 3 , the reference rectangular parallelepiped is illustrated by a two-dot chain line L1. Specifically, the container 100 has an outer shape that is long and flat in the X-axis direction, with triangular prism-shaped first notches 111 and 121 formed at the bottom of both ends in the X-axis direction. In other words, of the four corners of the long side of the reference rectangular parallelepiped, which are formed by the sides in the width and height directions, the first notches 111 and 121 are provided at the two corners in the negative Z-axis direction. When viewed from the reference rectangular parallelepiped, the first notches 111 and 121 can also be said to be chamfered. The first notched portions 111, 121 have inclined surfaces 112, 122 (surfaces) that are inclined in the XY plane and the YZ plane as a whole. Here, the inclined surfaces 112, 122 are illustrated as being generally flat, but may be curved surfaces.

[0044] Here, of the two end faces of the container 100 that face each other in the Z-axis direction, the end face facing the positive Z-axis direction is the top face 140, and the end face facing the negative Z-axis direction is the bottom face 150. Of the inclined faces 112, 122, the inclined face 112 facing the positive X-axis direction is continuous with the first side face 113 of the container 100 facing the positive X-axis direction and the bottom face 150. On the other hand, the inclined face 122 facing the negative X-axis direction is continuous with the second side face 123 of the container 100 facing the negative X-axis direction and the bottom face 150. At least one of the pair of inclined faces 112, 122 is provided with a gas exhaust valve 800. The gas exhaust valve 800 is a safety valve that releases pressure inside the container 100 when the pressure inside the container 100 rises excessively.

[0045] In this container 100, both end faces opposing each other in the Y-axis direction are long side faces 130. Each long side face 130 is a flat surface parallel to the XZ plane and elongated in the X-axis direction. The top surface 140 is the top surface of the container 100 connecting the upper end of the first side face 113 and the upper end of the second side face 123, and is a rectangular flat surface parallel to the XY plane and elongated in the X-axis direction. The bottom surface 150 is the bottom surface of the container 100 connecting the lower end of the inclined surface 112 and the lower end of the inclined surface 122, and is a rectangular flat surface parallel to the XY plane and elongated in the X-axis direction. The top surface 140 and the bottom surface 150 are continuous with the pair of long side faces 130.

[0046] 4, the container 100 includes a container body 160 and a lid 170, which are joined together. The lid 170 is a flat plate-shaped member having a top surface 140.

[0047] 5, the container body 160 is a box-like body that includes a pair of long side surfaces 130, a bottom surface 150, a first side surface 113, a second side surface 123, and inclined surfaces 112 and 122, and is open in the positive direction of the Z axis. The container body 160 is formed by welding a first member 161 and a second member 162 together.

[0048] 5 is an exploded perspective view showing an example of a method for assembling the container body 160 according to the embodiment. The first member 161 of the container body 160 includes a flat plate portion 163 having a long side surface 130 in the positive direction of the Y axis, and a peripheral wall portion 164 rising from the periphery of the flat plate portion 163. The peripheral wall portion 164 includes a bottom surface 150, a first side surface 113, a second side surface 123, and inclined surfaces 112 and 122. The second member 162 of the container body 160 is a flat plate-shaped member having the long side surface 130 in the negative direction of the Y axis. The first member 161 and the second member 162 are integrated by overlapping the peripheral edge of the second member 162 and the peripheral wall portion 164 of the first member 161 and joining (welding) them together.

[0049] FIG. 6 is an explanatory diagram for comparing the weld length of the container body 160 according to the embodiment with the weld length of the comparative example. (a) of FIG. 6 shows the outer shape of the end of the container body 160z1 according to the comparative example 1 in the positive X-axis direction, as viewed from the negative Y-axis direction. (b) of FIG. 6 shows the outer shape of the end of the container body 160z2 according to the comparative example 2 in the positive X-axis direction, as viewed from the negative Y-axis direction. (c) of FIG. 6 shows the outer shape of the end of the container body 160 according to the embodiment of the present invention in the positive X-axis direction, as viewed from the negative Y-axis direction. In (c) of FIG. 6, the outer shape of the container body 160z1 according to the comparative example 1 is indicated by a dashed line, and the outer shape of the container body 160z2 according to the comparative example 2 is indicated by a dashed line. The container body 160z1 according to the comparative example 1 does not have a first notch 111. The container body 160z2 according to the comparative example 2 has a rectangular notch 111z as viewed from the Y-axis direction.

[0050] Here, when the same electrode body 700 is used in Comparative Example 2 and this Example, it is considered that the length d1 of the first side of the rectangular cutout and the length d1 of the first side of the first notch of the present invention are approximately the same length. In Comparative Examples 1 and 2, the weld length at that location is the sum of the length d1 of the first side and the length d2 of the second side (d1 + d2). In contrast, in the container body 160 according to this embodiment, the weld length is the total length d of the inclined surface 112 as viewed from the Y-axis direction, so the weld length can be shorter than in Comparative Examples 1 and 2.

[0051] After the electrode body 700 and the like are housed in the container body 160 in which the first member 161 and the second member 162 are integrated, the container body 160 and the lid 170 are joined by welding or the like, thereby sealing the interior of the container 100. In this embodiment, the container body 160 in which the first member 161 and the second member 162 are integrated is exemplified, but the container body may be made of a single member. In this case, the container body 160 made of a single member can be manufactured by pressing or drawing a metal plate.

[0052] The material of the container 100 (container body 160 and lid 170) is not particularly limited, but is preferably a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet. Although not shown here, the lid 170 has a liquid injection portion formed therein. The liquid injection portion is a portion for injecting an electrolyte into the container 100 during the manufacture of the energy storage element 10.

[0053] 3 and 4 , the terminals 300 are terminals (positive electrode terminal and negative electrode terminal) electrically connected to the electrode body 700 via the current collector 600. In other words, the terminals 300 are metal members for conducting electricity stored in the electrode body 700 to the external space of the energy storage element 10 and for introducing electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode body 700. The material of the terminals 300 is not particularly limited, and the terminals 300 are formed, for example, from a conductive material such as aluminum, an aluminum alloy, copper, or a copper alloy. The terminals 300 are connected (joined) to the current collector 600 by crimping, welding, or the like, and are attached to the lid 170.

[0054] In the present embodiment, terminal 300 has terminal body 330 and shaft 340 protruding from terminal body 330. Terminal body 330 is a portion that protrudes outward from the terminal installation surface of container 100. Here, the terminal installation surface is top surface 140. Through holes 171, 172 through which shaft 340 passes are formed in lid 170 at locations corresponding to each terminal installation surface. Shaft 340 is connected (joined) to current collector 600 by being crimped in a state in which it passes through the terminal installation surface, external gasket 400, internal gasket 500, and current collector 600.

[0055] The current collectors 600 are arranged one each in the positive and negative X-axis directions of the electrode assembly 700, and are connected (joined) to the electrode assembly 700 and the terminal 300. These current collectors (positive electrode current collector 601 and negative electrode current collector 602) are conductive current collectors that electrically connect the electrode assembly 700 and the terminal 300. Specifically, the current collector 600 integrally includes a pair of legs 630 that are connected (joined) to the active material-free portion 720 of the electrode assembly 700 (described later) by welding, crimping, or the like, and a terminal joint 640 that is connected (joined) to the terminal 300 by crimping, welding, or the like, as described above. Each leg 630 and terminal joint 640 is a flat plate-shaped portion formed by bending a single sheet of metal. Each leg 630 extends from the terminal joint 640 in the negative Z-axis direction. The material of the current collector 600 is not particularly limited, but for example, the positive electrode current collector 601 is formed of a conductive material such as aluminum or an aluminum alloy, similar to the positive electrode current collector foil 741 of the electrode body 700 described later, and the negative electrode current collector 602 is formed of a conductive material such as copper or a copper alloy, similar to the negative electrode current collector foil 751 of the electrode body 700 described later.

[0056] The outer gasket 400 is a plate-shaped, rectangular insulating sealing member that is disposed between the lid 170 of the container 100 and the terminal 300, and provides insulation and a seal between the lid 170 and the terminal 300. The inner gasket 500 is a plate-shaped, rectangular insulating sealing member that is disposed between the lid 170 and the current collector 600, and provides insulation and a seal between the lid 170 and the current collector 600. The external gasket 400 and the internal gasket 500 are formed from an electrically insulating resin such as 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), ABS resin, or a composite material obtained by adding a filler to any of these resins.

[0057] [Electrode body] Fig. 7 is a perspective view showing an electrode body 700 according to an embodiment in the middle of its manufacture. As shown in Fig. 7, the electrode body 700 is an electricity storage element (power generation element) formed by winding electrode plates and capable of storing electricity. The electrode body 700 has an elongated shape extending in the X-axis direction and has an oval shape when viewed from the X-axis direction.

[0058] Specifically, the electrode assembly 700 includes two electrode plates, a positive electrode plate 740 and a negative electrode plate 750, and two separators 760, namely separators 761 and 762, as separators.

[0059] The positive electrode plate 740 is an electrode plate in which a positive electrode active material layer 742 is formed on the surface of a positive electrode current collector foil 741, which is a long, strip-shaped current collector foil (metal foil) made of a metal such as aluminum or an aluminum alloy. The negative electrode plate 750 is an electrode plate in which a negative electrode active material layer 752 is formed on the surface of a negative electrode current collector foil 751, which is a long, strip-shaped current collector foil (metal foil) made of a metal such as copper or a copper alloy. The positive electrode current collector foil 741 and the negative electrode current collector foil 751 may be made of any known material that is stable against oxidation-reduction reactions during charge and discharge, such as nickel, iron, stainless steel, titanium, baked carbon, conductive polymers, conductive glass, or an Al—Cd alloy. The positive electrode active material used in the positive electrode active material layer 742 and the negative electrode active material used in the negative electrode active material layer 752 may be any known material that is capable of absorbing and releasing charge-transport ions.

[0060] As a positive electrode active material, LiMPO ４ , LiMSiO ４ , LiMBO ３ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), polyanion compounds such as lithium titanate, LiMn ２ O ４ or LiMn １．５ Ni ０．５ O ４ Spinel-type lithium manganese oxides such as LiMO ２(M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) and the like can be used. Examples of the negative electrode active material include lithium metal, lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloy), alloys capable of absorbing and releasing lithium, carbon materials (graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), silicon oxides, metal oxides, and lithium metal oxides (Li ４ Ti ５ O １２ etc.), polyphosphate compounds, or Co, commonly called conversion anodes ３ O ４ or Fe ２ Examples of the metal include compounds of transition metals such as P and elements of Groups 14 to 16.

[0061] The separator 760 (separators 761, 762) is a microporous insulating sheet made of resin or the like. Any known material can be used as the material for the separator 760 as long as it does not impair the performance of the energy storage device 10. Examples of the separator 760 include woven fabric, nonwoven fabric, and porous resin film. Among these examples, porous resin film is preferred from the viewpoint of strength, and nonwoven fabric is preferred from the viewpoint of electrolyte retention. Polyolefins such as polyethylene and polypropylene are preferred from the viewpoint of shutdown function, and polyimide, aramid, and the like are preferred from the viewpoint of oxidative decomposition resistance. A composite material of these resins may also be used for the separator 760. The separators 761 and 762 may be formed of the same material or different materials.

[0062] The electrode assembly 700 is formed by alternately stacking and winding the positive electrode plates 740 and negative electrode plates 750 configured as described above and the separators 761 and 762. That is, the electrode assembly 700 is formed by stacking and winding the positive electrode plates 740, the separator 761, the negative electrode plates 750, and the separator 762 in this order. In this embodiment, the electrode assembly 700 is a wound electrode assembly formed by winding the positive electrode plates 740, the negative electrode plates 750, etc. around a winding axis L extending in the X-axis direction. The winding axis L is an imaginary axis that serves as the central axis when winding the positive electrode plates 740, the negative electrode plates 750, etc., and in this embodiment, is a straight line that passes through the center of the electrode assembly 700 and is parallel to the X-axis direction.

[0063] Specifically, the electrode body 700 is wound with a positive electrode plate 740 and a negative electrode plate 750 interposed between separators 761, 762 so as to be offset from each other in a direction along the winding axis L (the winding axis direction, the X-axis direction in this embodiment). The positive electrode plate 740 and the negative electrode plate 750 have active material-free portions 720 at their respective ends in the offset direction, where the positive electrode active material layer 742 and the negative electrode active material layer 752 are not formed (coated) and the positive electrode current collector foil 741 and the negative electrode current collector foil 751 are exposed. In other words, the electrode body 700 has, at one end in the winding axis direction, the positive electrode active material-free portions 720 formed by stacking and bundling the ends of the positive electrode current collector foil 741, and, at the other end in the winding axis direction, the negative electrode active material-free portions 720 formed by stacking and bundling the ends of the negative electrode current collector foil 751.

[0064] As described above, the electrode body 700 includes an electrode body main body portion 710 that constitutes the main body of the electrode body 700, and a pair of (positive and negative) active material non-forming portions 720 that protrude from the electrode body main body portion 710 in both the positive and negative X-axis directions. The electrode body main body portion 710 is an elongated cylindrical portion formed by winding the active material forming portions 713 of the electrode plates (positive electrode plate 740 and negative electrode plate 750) and the separator 760. As a result, the electrode body main body portion 710 includes a pair of curved portions 711 on both sides in the Z-axis direction and a pair of flat portions 712 on both sides in the Y-axis direction. In other words, the electrode body 700 includes the curved portions 711 and the flat portions 712 that are formed by winding the positive electrode plate 740 and the negative electrode plate 750 around the winding axis L.

[0065] The curved portions 711 are curved in a semicircular arc shape so as to protrude in the Z-axis direction when viewed from the X-axis direction, and are curved portions extending in the X-axis direction. The flat portions 712 are a pair of rectangular, flat portions extending parallel to the XZ plane, connecting the ends of the pair of curved portions 711. The curved shape of the curved portions 711 is not limited to a semicircular arc shape. The outer surface of the flat portion 712 facing the Y-axis direction is not limited to being flat, and the outer surface may be slightly concave or slightly bulged. In the flat portion 712, multiple wound electrode plates and separators (positive electrode plate 740, negative electrode plate 750, separators 761, 762) are stacked in the Y-axis direction.

[0066] With the above configuration, the electrode assembly 700 has a long (horizontally elongated) shape in which the length in the winding axis direction (X-axis direction) is longer than the height direction (Z-axis direction) and thickness direction (Y-axis direction). In other words, the length of the electrode assembly 700 in the X-axis direction is longer than the lengths of the electrode assembly 700 in both the Y-axis direction and the Z-axis direction. In this embodiment, the length of the electrode assembly 700 in the X-axis direction is preferably 300 mm or more, more preferably 500 mm or more, but may be shorter than 300 mm. In this embodiment, the length of the electrode assembly 700 in the X-axis direction is 1500 mm or less, but may be longer than 1500 mm.

[0067] The electrode body 700 manufactured by winding has a pair of corners 771, 772 in the negative Z-axis direction at both ends in the X-axis direction cut out by cutting. At this time, a pair of active material-free portions 720 (positive and negative electrodes) protruding from the electrode body main body 710 on both sides in the X-axis direction are cut out, while the electrode body main body 710 is not cut out. As a result, the portions of the electrode body 700 facing the first notched portions 111, 121 are chamfered (see FIG. 4 ). Here, because the electrode body main body 710 is not cut out, a decrease in storage capacity due to a decrease in the effective power generation area within the energy storage element 10 can be prevented.

[0068] The shape of the electrode body 700 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 in an accordion-like manner (a form in which the separator is folded in an accordion-like manner to sandwich a rectangular electrode plate, a form in which the electrode plate and separator are stacked and then folded in an accordion-like manner, etc.).

[0069] [Gas flow path within the exterior body] Next, the gas flow path S provided within the exterior body 2 will be described. Fig. 8 is an explanatory diagram showing the gas flow path S according to the embodiment. Here, the gas exhaust valve 800 is indicated by a dashed line. In this description, the gas flow path S corresponding to the first notch 111 of the energy storage element 10 is shown, but the same applies to the first notch 121.

[0070] As shown in Fig. 8 , multiple energy storage elements 10 are arranged in the same orientation within the exterior housing 2, and therefore the first notch 111 of each energy storage element 10 is continuous in the Y-axis direction. Therefore, a continuous space in the Y-axis direction is formed by the first notch 111 of each energy storage element 10 and the notch 21 of each spacer 20. This space is the gas flow path S. The gas flow path S is connected to an exhaust port 37 (see Fig. 2 ) in the positive direction of the X-axis, and gas that has passed through the gas flow path S is discharged from the exhaust port 37.

[0071] As described above, the width d1 of the first notch 111 is related to the size of the active material-free portion 720 of the electrode assembly 700 housed within the energy storage element 10. Therefore, as shown in Figure 8, increasing the width d1 of the first notch 111 is undesirable because it reduces the effective power generation area of ​​the energy storage element 10. Furthermore, it is also undesirable for the width d1 of the first notch 111 to be too small in order to accommodate the components involved in current collection of the electrode assembly 700 (such as the terminal 300, external gasket 400, internal gasket 500, and current collector 600) within the width d1 of the first notch 111. For this reason, assuming that the width d1 is constant, the gas discharge characteristics of the energy storage device 1 are significantly affected by the angle α between the inclined surface 112 of the container body 160 and the extension of the bottom surface 150 shown in Figure 8.

[0072] If the angle α is too small, the flow path area of ​​the gas flow path S will be small, which may make smooth exhaust difficult. On the other hand, if the angle α is too large, it will be difficult to secure the space necessary to accommodate the components involved in current collection of the electrode body 700 within the energy storage element 10 (such as the terminal 300, the external gasket 400, the internal gasket 500, and the current collector 600). From the viewpoint of securing the flow path area while also securing the space within the energy storage element 10 for accommodating the components involved in current collection, the angle α is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably 44° to 46°. The same applies to the inclined surface 122.

[0073] Furthermore, the larger the electrical capacity of the energy storage element 10, the larger the amount of gas likely to be released from the gas release valve 800. For this reason, it is desirable to make the gas release valve 800 larger. Here, when a gas release valve is provided in a rectangular cutout portion, as in the container body 160z2 of Comparative Example 2, the gas release valve is formed within the length d1 of the first side portion of the cutout portion or the length d2 of the second side portion of the cutout portion. In this embodiment, the gas release valve 800 can be disposed on the inclined surface 112 that is longer than the lengths d1 and d2, which allows the gas release valve 800 to be made larger, and in this respect, the present disclosure is also advantageous.

[0074] [Explanation of Effects] As described above, according to the embodiment, the container 100 of the energy storage element 10 is provided with the chamfered first notches 111, 121. Therefore, when the energy storage element 10 is housed in the outer casing 2, the first notches 111, 121 can form a space between the container 100 and the outer casing 2. Furthermore, the gas discharge valve 800 is provided on the inclined surfaces 112, 122 of the first notches 111, 121. Therefore, the space can be used as a flow path (gas flow path S) for gas discharged from the gas discharge valve 800. In other words, compared to a case where a separate gas flow path is provided, a compact and low-cost energy storage element 10 can be provided, and the energy density of the energy storage device 1 can be improved.

[0075] Fig. 9 is an explanatory diagram showing a state in which the electrode body 700 is housed in the container 100 according to the embodiment. As shown in Fig. 9, the electrode body 700 also has chamfered portions facing the first notched portions 111, 121, which makes it possible to suppress the generation of excess space between the electrode body 700 and the inner surface of the container 100 of the energy storage element 10. This allows the electrode body 700 to be made as large as possible, making it possible to increase the electrical capacity and further the volumetric energy density of the energy storage element 10.

[0076] [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.

[0077] (Variation 1) In the above embodiment, the terminal 300 is provided on the top surface 140 of the container 100, but the terminal may be provided on an outer surface other than the top surface. In this variation 1, an energy storage element in which a terminal is provided on each of a first side surface and a second side surface will be described. FIG. 10 is a perspective view showing an energy storage element 10a according to variation 1. As shown in FIG. 10 , one terminal 300a and an external gasket 400a are provided on the first side surface 113a of the container 100a. The other terminal 300a and an external gasket (not shown) are provided on the second side surface 123a of the container 100a. Even when the terminals 300a are provided on each of the first side surface 113a and the second side surface 123a, the gas exhaust valve 800 is provided on the inclined surfaces 112, 122 of the first notches 111, 121. Therefore, the volumetric energy density of the energy storage device 1 using the energy storage element 10 can be improved compared to when a separate gas flow path is provided.

[0078] (Variation 2) In the above embodiment, an example has been given of the energy storage element 10 in which a pair of first notches 111, 121 are provided at the corners of the bottom of the container 100. In this variation 2, a description will be given of the energy storage element 10 in which notches are also provided at the corners of the top of the container.

[0079] FIG. 11 is a perspective view showing an energy storage device 10b according to Modification 2. As shown in FIG. 11 , the container 100b of the energy storage device 10b has chamfered second notches 115b and 125b formed at two corners other than the first notches 111 and 121 when viewed from the Y-axis direction. That is, the container 100b has an outer shape that is a long and flat rectangular parallelepiped in the X-axis direction, with triangular prism-shaped first notches 111 and 121 formed at the bottom of both ends in the X-axis direction and triangular prism-shaped second notches 115b and 125b formed at the top. The second notches 115b and 125b have inclined surfaces 116b and 126b. Of the inclined surfaces 116b and 126b, the inclined surface 116b in the positive direction of the X-axis is continuous with the first side surface 113b facing the positive direction of the X-axis in the container 100 and with the top surface 140b. On the other hand, the inclined surface 126b in the negative X-axis direction is continuous with the second side surface 123b facing the negative X-axis direction and the top surface 140b of the container 100. A terminal 300b is installed on each of the inclined surfaces 116b and 126b via an external gasket 400b.

[0080] In this way, since the terminals 300b are provided in the second notches 115b and 125b, the welding length during container manufacturing can be shortened. This can improve the manufacturing efficiency of the energy storage elements 10b. Furthermore, by providing the terminals 300b in the second notches 115b and 125b, the terminals 300b and at least a portion of the bus bars connected to these terminals 300b can be housed in a triangular prism-shaped space, thereby reducing the space between the lid (exterior body lid 40) of the energy storage device 1 and the top of the energy storage elements 10b. This can improve the volumetric energy density of the energy storage device 1 using the energy storage elements 10b.

[0081] (Modification 3) In the above embodiment, the energy storage device 10 has flat top surface 140 and bottom surface 150. In Modification 3, an energy storage device having curved top surface and bottom surface will be described.

[0082] 12 is a perspective view showing an energy storage device 10c according to Modification 3. A top surface 140c of a container 100c provided in the energy storage device 10c is a curved surface that is convex in the positive Z-axis direction when viewed from the X-axis direction. The top surface 140c has a uniform shape over its entire length in the X-axis direction. Furthermore, a bottom surface 150c of the container 100c is a curved surface that is convex in the negative Z-axis direction when viewed from the X-axis direction. The bottom surface 150c has a uniform shape over its entire length in the X-axis direction.

[0083] Specifically, the wall portion of the container 100c having the top surface 140c is a curved wall portion 141c having a curved plate shape that is convex in the positive Z-axis direction when viewed from the X-axis direction. The curved wall portion 141c is disposed opposite the curved portion 711 of the electrode assembly 700 in the positive Z-axis direction, and this shape can reduce the excess space between the container 100 and the electrode assembly 700 of the energy storage device 10.

[0084] The wall portion of the container 100c having the bottom surface 150c is a curved wall portion 151c having a curved plate shape that is convex in the negative Z-axis direction when viewed from the X-axis direction. The curved wall portion 151c is disposed opposite the curved portion 711 of the electrode body 700 in the negative Z-axis direction, and its shape can reduce the excess space between the container 100 and the electrode body 700.

[0085] In the container 100c, the wall portion having each long side surface 130c is a flat plate-shaped flat wall portion 131c. Each flat wall portion 131c is arranged at a position sandwiching the electrode assembly 700 in the Y-axis direction (stacking direction). A pair of flat wall portions 131c is connected to each other by a pair of curved wall portions 141c, 151c. The pair of flat wall portions 131c abuts against a flat portion 712 of the electrode assembly 700.

[0086] One terminal 300c and an external gasket 400c are disposed on a first side surface 113c of the container 100c, and the other terminal 300c and an external gasket (not shown) are disposed on a second side surface 123c of the container 100c.

[0087] Each of the first notches 111c, 121c is chamfered so as to cut out a part of the pair of flat wall portions 131c and a part of the curved wall portion 151c. In this way, even in the energy storage element 10c having a pair of flat wall portions 131c and a pair of curved wall portions 141c, 151c, the gas release valve 800 is provided on at least one of the inclined surfaces 112c, 122c of the first notches 111c, 121c, so that the volumetric energy density of the energy storage device 1 using the energy storage element 10c can be improved compared to when a separate gas flow path is provided.

[0088] Furthermore, since each flat wall portion 131c abuts entirely against each flat portion 712 of the electrode body 700, and each curved wall portion 141c, 151c abuts entirely against each curved portion 711, the electrode body 700 can be compressed by the container 100 in response to expansion of the curved portion 711 in the same manner as expansion of the flat portion 712. This makes it possible to suppress local damage due to deformation of the electrode body 700.

[0089] (Others) Although the energy storage element according to the embodiment of the present invention (including its modified examples, the same applies hereinafter) has been described above, the present invention is not limited to the above-described embodiment. The embodiment disclosed herein is an example in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0090] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention.

[0091] The present invention can be applied to an energy storage device such as a lithium ion secondary battery.

[0092] REFERENCE SIGNS LIST 1 Energy storage device 2 Exterior body 10, 10a, 10b, 10c Energy storage element 20 Spacer 21 Cutout portion 30 Exterior body main body 31 Opening 32 Bottom wall 33 Side wall 37 Exhaust port 40 Exterior body lid 100, 100a, 100b, 100c Container 110 First side region 111, 111c, 121, 121c First cutout portion 112, 112c, 116b, 122, 122c, 126b Inclined surface (surface) 113, 113a, 113b, 113c First side 115b, 125b Second cutout portion 120 Second side region 123, 123a, 123b, 123c Second side 130, 130c Long side 131c Flat wall portion 140, 140b, 140c Top surface 141c Curved wall portion 150, 150c Bottom surface 151c Curved wall portion 160, 160z1 Container body 161 First member 162 Second member 163 Flat plate portion 164 Peripheral wall portion 170 Lid body 300, 300a, 300b, 300c Terminal 700 Electrode body 771, 772 Corner portion 800 Gas exhaust valve d Total length d1, d2 Length L Winding axis L1 Two-dot chain line S Gas flow path α Angle

Claims

1. An energy storage element comprising: an electrode assembly formed by stacking electrode plates; a container for accommodating the electrode assembly; and terminals installed on the outer surface of the container and electrically connected to the electrode assembly, wherein the container is shaped based on a rectangular parallelepiped, and when the rectangular parallelepiped shape has width (L), height (H), and thickness (T), the relationship is L>H>T, and at least one of the four corners of the long side formed by the sides in the width and height directions is a first notch that is triangular prism-shaped in the thickness direction of the rectangular parallelepiped and is cut out in a chamfered shape, and a gas release valve is provided on the surface of the first notch.

2. The energy storage element according to claim 1, wherein chamfered, triangular prism-shaped second cutouts are formed in the two corners of the long side surface of the container other than the first cutout, and the terminals are arranged in the second cutouts.

3. The energy storage element according to claim 1, wherein the container has a first side surface adjacent to the first notch in the height direction and a second side surface opposite the first side surface, and the terminals are arranged on each of the first side surface and the second side surface.

4. The energy storage device according to any one of claims 1 to 3, wherein the container has a pair of curved wall portions on its upper and lower surfaces connecting the pair of long sides of the container.

5. The energy storage element according to any one of claims 1 to 3, wherein the electrode body is chamfered at a location facing the first notch.

6. An electricity storage device in which a plurality of the electricity storage elements according to any one of claims 1 to 3 are stacked so that the first notches are continuous with each other.

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