Power storage element and power storage device

Abstract

This power storage element of the present embodiment is characterized by comprising an electrode body in which a plurality of electrode plates are layered, a container that accommodates the electrode body, and a pair of electrode terminals that are electrically continuous with the electrode body. The power storage element is also characterized in that: the container, when observed from a first direction, which is a prescribed horizontal direction, has a rectangular shape that is long in a second direction which is perpendicular to the first direction and horizontal, and among the four corners of the rectangular shape, at least two corners on one side in the vertical direction each have a notch; the notch comprises a terminal disposition surface that extends in an oblique direction that intersects both a long side and short side of the rectangular shape which is observed from the first direction, the long side being on the one side in the vertical direction, and the short side being on one side in the second direction of the rectangular shape or being on the other side in the second direction; and the electrode terminals are disposed on the respective terminal disposition surfaces.

Description

Energy storage element and energy storage device

[0001] The present invention relates to an energy storage element and an energy storage device including a plurality of energy storage elements.

[0002] A rectangular parallelepiped secondary battery (electricity storage element) has been known (see Patent Document 1). As shown in Fig. 9, this secondary battery 500 includes a battery case (container) 501 that houses a flat wound electrode body, and a positive electrode terminal 504 and a negative electrode terminal 505 that are disposed in the battery case 501.

[0003] Specifically, the battery case 501 includes a case body 502 that is a flat, box-shaped (rectangular parallelepiped) body with a bottom and an open top, and a lid 503 that closes the opening of the case body 502. A positive electrode terminal 504 that electrically connects to the positive electrode sheet of the flat wound electrode body, and a negative electrode terminal 505 that electrically connects to the negative electrode sheet of the flat wound electrode body are provided on the top surface of the battery case 501 (i.e., the lid 503). The positive electrode terminal 504 and the negative electrode terminal 505 are provided to protrude upward from the lid 503.

[0004] When a plurality of such secondary batteries 500 are arranged in a row and the corresponding terminals (positive electrode terminals 504 and negative electrode terminals 505) of adjacent secondary batteries 500 are housed in an element container 506 in a state where they are connected to each other by a bus bar B to form an energy storage device 507, the positive electrode terminals 504 and the negative electrode terminals 505 protrude upward from the battery case 501. As shown in FIG. 10 , therefore, a dead space DS (the range indicated by dots in FIG. 10 ) is generated between the upper surface of the battery case 501 and the upper inner wall surface of the element container 506, and the energy density inside the element container 506 is reduced, which in turn reduces the energy density of the energy storage device 507 itself.

[0005] JP 2020-129474 A

[0006] Therefore, the present embodiment aims to provide a storage element that can improve the energy density of a storage device when the storage element is housed in the storage device, and a storage device including this storage element.

[0007] The energy storage element of this embodiment comprises an electrode body formed by stacking a plurality of electrode plates; a container that houses the electrode body; and a pair of electrode terminals that are electrically connected to the electrode body. When viewed from a first direction that is a predetermined horizontal direction, the container has a rectangular shape that is elongated in a second horizontal direction that is perpendicular to the first direction, and has notched shapes at at least two corners on one side in the vertical direction out of four corners of the rectangular shape. Each of the notched shapes is formed by a terminal arrangement surface that extends along an inclined direction that intersects with each of the long side on one side in the vertical direction and each of the short side on one side in the second direction of the rectangular shape when viewed from the first direction, and each of the electrode terminals is provided on the terminal arrangement surface.

[0008] Furthermore, the energy storage device of this embodiment includes a plurality of energy storage elements of this embodiment arranged in the first direction, and at least one bus bar that electrically connects the corresponding electrode terminals of at least adjacent energy storage elements, and the corresponding terminal arrangement surfaces of the adjacent energy storage elements are arranged in the first direction along a common imaginary plane that extends in the inclination direction and the first direction.

[0009] As described above, according to the present invention, when the energy storage element is housed in an energy storage device, it is possible to reduce the dead space between the upper surface of the battery case and the upper inner wall surface of the element container, and this space can be used to increase the size of the energy storage element, thereby increasing the amount of effective active material in the electrode body in the energy storage device and improving the energy density of the energy storage device. Therefore, the present invention can provide an energy storage element that can improve the energy density of an energy storage device, and an energy storage device including this energy storage element.

[0010] FIG. 1 is a perspective view of an energy storage device according to this embodiment. FIG. 2 is an exploded perspective view of the energy storage device. FIG. 3 is a perspective view of an energy storage element included in the energy storage device. FIG. 4 is an exploded perspective view of the energy storage element. FIG. 5 is a diagram for explaining the configuration of an electrode body included in the energy storage element. FIG. 6 is a view of the energy storage element with an intermediate portion omitted. FIG. 7 is a vertical cross-sectional view of the energy storage device with an intermediate portion omitted. FIG. 8 is a perspective view of an energy storage element according to another embodiment. FIG. 9 is a perspective view of a conventional secondary battery. FIG. 10 is a vertical cross-sectional view of an energy storage device including the secondary battery.

[0011] (1) An energy storage element according to one embodiment of the present invention comprises: an electrode body formed by stacking a plurality of electrode plates; a container that houses the electrode body; and a pair of electrode terminals that are electrically connected to the electrode body. When viewed from a first direction that is a predetermined horizontal direction, the container has a rectangular shape that is elongated in a second horizontal direction that is perpendicular to the first direction, and at least two of the four corners of the rectangular shape have notched shapes on one side in the vertical direction, and each of the notched shapes is formed by a terminal arrangement surface that extends along an inclined direction that intersects with a long side on one side in the vertical direction and a short side on one side in the second direction of the rectangular shape when viewed from the first direction, or a short side on the other side in the second direction of the rectangular shape, and each of the electrode terminals is provided on the terminal arrangement surface.

[0012] According to one embodiment of the present invention, the electrode terminals are arranged along the terminal arrangement surfaces provided at the two corners of the rectangular shape when the container is viewed from the first direction. This reduces the dead space (excess space) caused by the protrusion of the electrode terminals when the storage element is housed in the element container and the dead space caused by the bus bar connection between the electrode terminals, thereby improving the energy density of the storage device when the storage element is housed in the storage device.

[0013] (2) In the energy storage device described in (1) above, the electrode terminals may be located within a projection area of ​​the terminal arrangement surface in the up-down direction and within a projection area of ​​the terminal arrangement surface in the second direction.

[0014] According to the energy storage element described in (2) above, when a plurality of energy storage elements are arranged in the first direction, unintentional contact between the electrode terminals of adjacent energy storage elements is suppressed. Also, when a plurality of energy storage elements are arranged in the first direction, protrusion of the electrode terminals from one edge position of each energy storage element in the vertical direction and protrusion of the electrode terminals from both edge positions of each energy storage element in the second direction are suppressed when viewed from the first direction.

[0015] (3) In the energy storage element described in (1) above, the electrode body may be configured by winding the electrode plate so that it has an elliptical shape when viewed from the second direction, and the container may have an elliptical shape corresponding to the electrode body when viewed from the second direction.

[0016] According to the energy storage element described in (3) above, when the wound electrode body is housed in a container, the gap between the outer periphery of the electrode body and the inner surface of the container becomes small, which increases the energy density of the energy storage element and enables the electrode body to be uniformly pressurized by the container, preventing deformation of the electrode body due to charging and discharging (see, for example, FIG. 8).

[0017] (4) An energy storage device according to one embodiment of the present invention comprises: a plurality of energy storage elements according to any one of (1) to (3) above, arranged in the first direction; and at least one bus bar that electrically connects the corresponding electrode terminals of at least adjacent energy storage elements, wherein the corresponding terminal arrangement surfaces of the adjacent energy storage elements are arranged in the first direction along a common imaginary plane that extends in the inclination direction and the first direction.

[0018] According to one embodiment of the present invention, the electrode terminals are arranged along the terminal arrangement surfaces provided at the two corners of the rectangular shape when the container is viewed from the first direction. This reduces the dead space caused by the protrusion of the electrode terminals when multiple storage elements are housed in the storage device, thereby improving the energy density of the storage device.

[0019] (5) The energy storage device described in (4) above includes an element container in which at least one of a plurality of inner surfaces defining an internal storage space is a cooling surface, and the element container may house an energy storage element group including the plurality of energy storage elements and the at least one bus bar so that the energy storage element group is in contact with the cooling surface.

[0020] According to the energy storage device described in (5) above, the energy storage elements housed in the element container are cooled by being in contact with the cooling surface, and therefore, a temperature rise of the energy storage elements during charging and discharging is suppressed.

[0021] (6) In the energy storage device described in (5) above, the bus bar may be located within a projection area of ​​the terminal arrangement surface in the vertical direction and within a projection area of ​​the terminal arrangement surface in the second direction, when viewed from the first direction.

[0022] According to the energy storage device described in (6) above, the bus bars do not protrude outward in the second direction or to one side in the vertical direction when viewed from the first direction in the energy storage element group, thereby preventing the occurrence of dead space within the storage space due to the protrusion of the bus bars (see, for example, Figure 7).

[0023] An embodiment of the present invention will be described below with reference to Figures 1 to 7. Note that the names of the components in this embodiment are those used in this embodiment and may differ from the names of the components in the background art.

[0024] In the following description and drawings, the longitudinal direction of the energy storage element and the direction along the winding axis of the electrode body provided in the energy storage element are defined as the X-axis direction (second direction). The arrangement direction of the multiple energy storage elements and the thickness direction of the container of the energy storage element are defined as the Y-axis direction (first direction). The arrangement direction of the case lid and case body of the energy storage device, the arrangement direction of the bottom surface of the container body and the top surface of the lid, or the up-down direction are defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). In the following description, the term "insulation" means "electrical insulation." In this embodiment, for example, 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 and Z-axis directions.

[0025] An electric storage device is a device that can charge electricity from an external source and discharge electricity to an external source. The electric storage device 1 of this embodiment has a substantially rectangular parallelepiped shape as shown in FIG. 1 . The electric storage device 1 is a battery module (battery assembly) used for power storage or power supply purposes, and is used, for example, as a battery for driving or starting the engine of a moving object such as an automobile, motorcycle, personal watercraft, boat, snowmobile, agricultural machinery, construction machinery, 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, an automatic guided vehicle (AGV), and a hybrid electric train equipped with both a diesel engine and an electric motor. The power storage device 1 can also be used as a stationary battery for home or business use.

[0026] 2 and 3 , the energy storage device 1 includes an energy storage element group 3 including a plurality of energy storage elements 10 and at least one (a plurality in this embodiment) bus bar 30, and a case portion (element container) 2 that houses the energy storage element group 3. In addition to the above-mentioned components, the energy storage device 1 may also include restraining members (end plates, side plates, etc.) that restrain the plurality of energy storage elements 10, a bus bar holder that holds the bus bar 30, a bus bar cover, a circuit board that monitors or controls the charge state and discharge state of the energy storage elements 10, and electrical components such as a relay, a fuse, a shunt resistor, and a connector.

[0027] The case portion 2 has a case 20 having an accommodation space S therein, and a refrigerant pipe 26 for cooling the energy storage element group 3 via the case 20 .

[0028] The case 20 is a substantially rectangular parallelepiped (box-shaped) container (module case) that constitutes the exterior body (housing, outer shell) of the energy storage device 1, and the storage space S is also rectangular or substantially rectangular. That is, the case 20 has six (plural) inner surfaces 20S that define the storage space S, and each inner surface 20S is a flat, rectangular surface.

[0029] This case 20 accommodates the energy storage element group 3 in the accommodation space S, thereby fixing (holding) the energy storage element group 3 etc. in a predetermined position, thereby protecting each energy storage element 10 included in the energy storage element group 3 from impact, vibration, etc. In the case 20 of this embodiment, after each energy storage element 10 is compressed and accommodated in the case 20, each energy storage element 10 is fixed in the case 20 by the restoring force of the energy storage element 10.

[0030] The case 20 is a metal case formed from a metal member such as aluminum, aluminum alloy, stainless steel, iron, or plated steel sheet. Therefore, the case 20 can efficiently dissipate heat from each energy storage element 10 to the outside of the case 20, and can suppress or cool each energy storage element 10. If the case 20 is conductive, the inner surface of the case 20 may be coated with an insulating material to ensure insulation from the energy storage element group 3. The case 20 is not limited to being made of metal, and may be made of resin, etc.

[0031] Case 20 of this embodiment has case body 21 which has opening 21A and constitutes the main body of case 20, and case lid 25 which closes opening 21A. In addition, in case 20 of this embodiment, case body 21 and case lid 25 are made of the same material, but they may also be made of different materials.

[0032] The case body 21 is a rectangular cylinder with a bottom and has an opening 21A on the positive side in the Z-axis direction (upper side in FIG. 2), and accommodates the energy storage element group 3 and the like.

[0033] Specifically, the case body 21 has a plate-shaped bottom wall 22 that extends in a plane direction perpendicular to the Z-axis direction, and a peripheral wall 23 that extends from the peripheral edge of the bottom wall 22 to the positive side of the Z-axis direction. In this embodiment, the bottom wall 22 is rectangular, and the peripheral wall 23 is square-tube.

[0034] The peripheral wall 23 is configured by four rectangular plate-shaped side walls (a first side wall 231, a second side wall 232, a third side wall 233, and a fourth side wall 234) that are continuously arranged in the circumferential direction along the peripheral edge of the bottom wall 22. In the peripheral wall 23 of this embodiment, the first side wall 231 has a first general terminal 235, and the third side wall 233 has a second general terminal 236. The positions of the general terminals on the peripheral wall 23 are not limited. That is, the positions of the general terminals on the peripheral wall 23 vary depending on the terminal positions of the energy storage elements 10, the number of energy storage elements 10 arranged in the case 20 (number of stacks), the series / parallel relationship of the energy storage elements 10 and the energy storage element group 3 in the case 20, etc.

[0035] The first general terminal 235 is a terminal for inputting electricity from outside the case 20 to the energy storage element group 3 housed in the case 20, or for outputting electricity from the energy storage element group 3 to the outside of the case 20. In this embodiment, the first general terminal 235 is disposed at the end of the first side wall 231 on the negative side in the X-axis direction (the left side in FIG. 2 ) and on the positive side in the Z-axis direction.

[0036] The second general terminal 236 is a terminal for outputting electricity from the energy storage element group 3 housed in the case 20 to the outside of the case 20, or for inputting electricity from the outside of the case 20 to the energy storage element group 3. In this embodiment, the second general terminal 236 is disposed at the end of the third side wall 233 on the positive side in the X-axis direction (the right side in FIG. 2 ) and on the positive side in the Z-axis direction.

[0037] The case cover 25 is a portion or member that closes the rectangular opening 21A of the case body 21, and is a rectangular plate provided on the XY plane.

[0038] In the case 20 of this embodiment, the case body 21 and the case lid 25 configured as described above are joined by welding, melting, screwing, or the like, thereby sealing the storage space S.

[0039] The refrigerant pipe 26 cools the energy storage element group 3 via the case 20 by circulating a refrigerant such as a gas or fluid therethrough, and in this embodiment, the refrigerant pipe 26 is arranged on the outer surface of the case 20 (not shown in FIG. 2 ). The refrigerant pipe 26 is joined to the case 20 by welding. In this embodiment, the refrigerant pipe 26 is arranged in a bellows shape on each outer surface of two side walls (the second side wall 232 and the fourth side wall 234) facing each other in the X-axis direction, on the lower surface of the bottom wall 22, and on the upper surface of the case lid 25. The refrigerant flows through the refrigerant pipe 26, thereby cooling the case 20 (the portion where the refrigerant pipe 26 is arranged), and as a result, at least one of the multiple inner surfaces 20S of the case 20 forms a cooling surface 20CS.

[0040] The cooling surface 20CS is a surface that can cool the energy storage element group 3 (more specifically, each energy storage element 10) housed in the housing space S of the case 20 by coming into contact with the energy storage element group 3 (more specifically, each energy storage element 10) (see FIG. 7 ). In the case 20 of this embodiment, the second side wall 232, the fourth side wall 234, the bottom wall 22, and the case lid 25 are cooled by refrigerant pipes 26 through which a refrigerant flows, and the inner surfaces 20S of these walls 232, 234, 22, and 25 each constitute a cooling surface 20CS. In other words, the case 20 of this embodiment has four cooling surfaces 20CS. Note that this embodiment has been described from the perspective of cooling the energy storage elements 10, but it goes without saying that the structure of this embodiment is useful not only for cooling but also for heating the energy storage elements 10 in an extremely low-temperature environment.

[0041] The energy storage element group 3 includes a plurality of energy storage elements 10 arranged in the Y-axis direction, each having a pair of electrode terminals 140 (a positive terminal 140A and a negative terminal 140B), and a plurality of bus bars 30 that connect (conduct) the corresponding electrode terminals 140 of adjacent energy storage elements 10. In the energy storage element group 3 of this embodiment, the plurality of energy storage elements 10 are arranged in the Y-axis direction such that the corresponding electrode terminals of adjacent energy storage elements 10 (more specifically, the electrode terminals 140 connected by the bus bars 30) have mutually opposite polarities (i.e., the positive terminal 140A and the negative terminal 140B are adjacent to each other in the Y-axis direction). As a result, the energy storage elements 10 of the energy storage element group 3 are connected in series to each other.

[0042] The energy storage element 10 charges with electricity from an external source and discharges electricity to the external source. The energy storage element 10 of this embodiment is a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery, but is not limited thereto. It may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may also be a primary battery that can use stored electricity without the user having to charge it, instead of a secondary battery. The energy storage element 10 may also be, for example, an all-solid-state lithium battery using a solid electrolyte, or a polymer lithium battery. The energy storage element 10 may also be a pouch-type energy storage element. The energy storage element 10 of this embodiment has a generally rectangular parallelepiped shape that is elongated in the X-axis direction. However, the shape of the energy storage element 10 is not limited to a generally rectangular parallelepiped shape, and may be a polygonal prism, an elongated cylinder, an elliptical cylinder, a cylindrical shape, or the like.

[0043] The energy storage element 10 of this embodiment has a shape in which the dimension in the X-axis direction is larger than the dimension in the Y-axis direction, specifically, a rectangular parallelepiped shape (square, rectangular) that is flat in the Y-axis direction and elongated in the X-axis direction. As shown in FIGS. 3 to 6 , this energy storage element 10 includes an electrode assembly 110 in which multiple electrode plates 113, 114 are stacked, a container 120 that houses the electrode assembly 110, and a pair of electrode terminals 140 that are electrically connected to the electrode assembly 110. The energy storage element 10 also includes a pair of external gaskets (insulating portions) 150 on the outside of the container 120. The energy storage element 10 also includes a pair of internal gaskets 160 and a pair of current collectors 170 inside the container 120.

[0044] The electrode body 110 is a storage element (power generating element) capable of storing electricity, and is formed by winding a plurality of electrode plates 113, 114 in a stacked state. The electrode body 110 of this embodiment has an elongated shape in the X-axis direction and an oval shape (racetrack shape) when viewed from the X-axis direction. The electrode body 110 has a larger dimension in the X-axis direction than in the Z-axis direction. The dimension of the electrode body 110 of this embodiment in the X-axis direction is, for example, 300 mm or more, specifically, approximately 500 mm to 1500 mm. Furthermore, the electrode body 110 of this embodiment has, for example, a dimension in the X-axis direction that is three times or more the dimension in the Z-axis direction. Specifically, the electrode body 110 has a main body portion 111 and a plurality of tab portions 112 protruding from the main body portion 111.

[0045] The multiple tab portions 112 are portions (connections) of the electrode body 110 that are connected (joined) to the current collector 170, and in the electrode body 110 of this embodiment, one tab portion 112 protrudes from each of both ends of the main body portion 111 in the X-axis direction. That is, the electrode body 110 has two tab portions 112. For example, a positive electrode tab portion 112a is disposed at the end of the main body portion 111 on the positive side in the X-axis direction, and a negative electrode tab portion 112b is disposed at the end of the main body portion 111 on the negative side in the X-axis direction. Note that the tab portions 112 shown in FIGS. 4 and 5 are an example of connections that are connected to the current collector 170, and this embodiment is not limited to this configuration.

[0046] Specifically, the electrode assembly 110 includes a positive electrode plate 113 , a negative electrode plate 114 , and separators 115 and 116 .

[0047] The positive electrode plate 113 has a positive electrode current collector foil 1131 which is a long strip of metal foil, and positive electrode active material layers 1132 which are disposed on both sides of the positive electrode current collector foil 1131 .

[0048] The positive electrode current collector foil 1131 is made of aluminum or an aluminum alloy. The positive electrode active material constituting the positive electrode active material layer 1132 is 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, LiMn２ O ４ and LiMn １．５ Ni ０．５ O ４ Spinel-type lithium manganese oxides such as α-NaFeO ２ LiMO having a type crystal structure ２ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) As the positive electrode active material used in the positive electrode active material layer 1132, any known material can be used as long as it is capable of absorbing and releasing charge transport ions.

[0049] Furthermore, a plurality of protruding pieces 1133 protruding outward are arranged at intervals on the edge on the positive side in the X-axis direction of the positive electrode plate 113. Each protruding piece 1133 is a portion where no positive electrode active material layer is disposed and the positive electrode current collector foil 1131 is exposed (a portion where no positive electrode active material layer is formed), and is a portion indicated by hatching in Fig. 5 .

[0050] The negative electrode plate 114 has a negative electrode current collector foil 1141 which is a long strip of metal foil, and negative electrode active material layers 1142 which are disposed on both sides of the negative electrode current collector foil 1141 .

[0051] The negative electrode current collector foil 1141 is made of copper or a copper alloy, etc. The negative electrode active material constituting the negative electrode active material layer 1142 is lithium metal, an alloy capable of absorbing and desorbing lithium, a carbon material (graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), silicon oxide, etc. Any known material can be used as the negative electrode active material used in the negative electrode active material layer 1142 as long as it is capable of absorbing and desorbing charge transport ions.

[0052] Furthermore, a plurality of protruding pieces 1143 protruding outward are arranged at intervals on the edge on the negative side in the X-axis direction of the negative electrode plate 114. Each protruding piece 1143 is a portion where no negative electrode active material layer is disposed and the negative electrode current collector foil 1141 is exposed (negative electrode active material layer non-formed portion), and is a portion indicated by hatching in Fig. 5 .

[0053] The separators 115, 116 are microporous sheets made of resin. Any known material can be used as the material for the separators 115, 116 as long as it does not impair the performance of the energy storage device 10. For example, the separators 115, 116 are woven fabric or nonwoven fabric that is insoluble in organic solvents, or a synthetic resin microporous film made of a polyolefin resin such as polyethylene.

[0054] The electrode assembly 110 is formed by winding the positive electrode plate 113, the negative electrode plate 114, and the separators 115 and 116 configured as described above in a stacked state. In the electrode assembly 110 of this embodiment, the positive electrode plate 113, the negative electrode plate 114, and the separators 115 and 116 are wound around a winding axis L extending in the X-axis direction using a winding core having an oval cross section (racetrack shape), thereby forming the wound electrode assembly 110. The winding axis L is a virtual axis that serves as the central axis when winding the positive electrode plate 113, the negative electrode plate 114, and the separators 115 and 116, and in this embodiment, the winding axis L is a straight line that passes through the center of the electrode assembly 110 and is parallel to the X-axis direction (see FIG. 5 ).

[0055] Furthermore, by winding the positive electrode plate 113, the negative electrode plate 114, and the separators 115 and 116 in a stacked state in order, the multiple protruding pieces 1133 of the positive electrode plate 113 overlap at the positive end of the main body 111 in the X-axis direction, and the multiple protruding pieces 1143 of the negative electrode plate 114 overlap at the negative end of the main body 111 in the X-axis direction.

[0056] In the electrode body 110, the positive electrode tab portion 112a is a portion where the multiple protruding pieces 1133 of the positive electrode plate 113 overlap. That is, the positive electrode tab portion 112a is a portion where the multiple pieces (protruding pieces 1133) provided on the electrode plate (positive electrode plate 113) of the same polarity among the multiple electrode plates (positive electrode plate 113 and negative electrode plate 114) are stacked.

[0057] Similarly, in the electrode body 110, the portion where the multiple protruding pieces 1143 of the negative electrode plate 114 overlap is the negative electrode tab portion 112b. That is, the negative electrode tab portion 112b is a portion where multiple pieces (protruding pieces 1143) provided on the electrode plate (negative electrode plate 114) of the same polarity among the multiple electrode plates (positive electrode plate 113 and negative electrode plate 114) are stacked.

[0058] As described above, the electrode body 110 has a main body portion 111 that constitutes the main body of the electrode body 110, and tab portions 112 (positive electrode tab portion 112a and negative electrode tab portion 112b) that protrude from each end portion in the X-axis direction of the main body portion 111. That is, the electrode body 110 has a pair of tab portions 112 that are constituted by the positive electrode tab portion 112a and the negative electrode tab portion 112b.

[0059] The main body portion 111 is an elongated cylindrical portion formed by winding together a portion of the positive electrode plate 113 where the positive electrode active material layer 1132 is disposed (formed, coated), a portion of the negative electrode plate 114 where the negative electrode active material layer 1142 is disposed (formed, coated), and separators 115 and 116. In the main body portion 111, the region where at least one of the positive electrode active material layer 1132 and the negative electrode active material layer 1142 is laminated is referred to as an active material layer formation portion. Furthermore, because the main body portion 111 has an elongated cylindrical shape, the outer surface (outer peripheral surface) of the main body portion 111 has curved portions 1111 at both ends in the Z-axis direction and flat portions 1112 at both ends in the Y-axis direction.

[0060] Curved portion 1111 is a surface that extends in the X-axis direction and is curved so as to be convex outward in the Z-axis direction (the side away from winding axis L). In this embodiment, curved portion 1111 is curved in a semicircular arc shape when viewed in the X-axis direction.

[0061] The flat portion 1112 is a flat surface extending in the X-axis direction and along the XZ plane connecting the ends of the pair of curved portions 1111. In a portion of the main body 111 corresponding to the flat portion 1112 (more specifically, a portion sandwiched between the pair of flat portions 1112 in the Y-axis direction), a plurality of electrode plates and separators (positive electrode plate 113, negative electrode plate 114, separators 115, 116) are stacked in the Y-axis direction.

[0062] The shape of the electrode body 110 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 at least one of the electrode plates and the separator is folded accordion-like (a form in which the separator is folded accordion-like and a rectangular electrode plate is sandwiched between it, a form in which the electrode plate and the separator are stacked and folded accordion-like, etc.).

[0063] The container 120 that houses the electrode body 110 configured as described above has a rectangular shape that is elongated in the X-axis direction (a horizontal direction perpendicular to the Y-axis direction) when viewed from the Y-axis direction (a predetermined horizontal direction), and has notches (notches 131, 132) at least in the two corners on the positive side in the Z-axis direction out of the four corners of the rectangle. These notches in the two corners on the positive side in the Z-axis direction are formed by inclined surfaces (terminal placement surfaces) 1211, 1221 that extend in inclined directions that intersect with the short and long sides of the rectangle when viewed from the Y-axis direction.

[0064] Specifically, the container 120 has an outer shape (approximately rectangular parallelepiped shape) based on a rectangular parallelepiped shape that is long in the X-axis direction and flat in the Y-axis direction. For example, the dimension of the container 120 in the X-axis direction is three or more times the dimension in the Z-axis direction. In Figures 3 and 6, the rectangular parallelepiped shape that serves as the basis is illustrated by a two-dot chain line L1.

[0065] The container 120 of this embodiment has an outer shape that is long and flat in the X-axis direction, with rectangular notches formed at the upper end of each end in the X-axis direction (the end on the positive side in the Z-axis direction). Furthermore, at the end on the positive side in the Z-axis direction of the container 120, notches 131 and 132 are spaced apart in the X-axis direction. Electrode terminals 140 are disposed in these notches 131 and 132, respectively.

[0066] Specifically, the first side end surface portion 121 is the end surface on the positive side in the X-axis direction of the container 120, has a first upper inclined surface (terminal arrangement surface) 1211 and a first side surface 1212, and is elongated in the Z-axis direction when viewed from the X-axis direction.

[0067] The first upper inclined surface 1211 is disposed at the upper end (the end on the positive side in the Z-axis direction) of the first side end surface portion 121, and is a rectangular plane inclined with respect to both the X-axis direction and the Z-axis direction when viewed from the Y-axis direction. That is, the first upper inclined surface 1211 is a plane that is positioned from the positive side in the Z-axis direction to the negative side in the Z-axis direction as it progresses from the negative side in the X-axis direction to the positive side in the X-axis direction when viewed from the Y-axis direction. Furthermore, the first side surface 1212 is a plane that extends downward from the lower end of the first upper inclined surface 1211, and is a rectangular plane that is parallel to the YZ plane and is elongated in the Z-axis direction.

[0068] The notch 131 of the first side end surface 121 is formed by the first upper inclined surface 1211. In other words, the notch 131 of the first side end surface 121 has a so-called chamfered corner (corner) on the positive side in the X-axis direction and on the positive side in the Z-axis direction of the container 120.

[0069] In addition, the second side end surface portion 122 is the end surface on the negative side in the X-axis direction of the container 120, and has a second upper inclined surface (terminal arrangement surface) 1221 and a second side surface 1222, and is elongated in the Z-axis direction when viewed from the X-axis direction.

[0070] The second upper inclined surface 1221 is located at the upper end (the end on the positive side in the Z-axis direction) of the second side end surface portion 122 and is a rectangular plane inclined with respect to both the X-axis direction and the Z-axis direction when viewed from the Y-axis direction. That is, the second upper inclined surface 1221 is a plane located from the positive side in the Z-axis direction to the negative side in the Z-axis direction as viewed from the Y-axis direction. Furthermore, the second side surface 1222 is a plane extending downward from the lower end of the second upper inclined surface 1221. In the container 120 of this embodiment, the second upper inclined surface 1221 has the same shape and size as the first upper inclined surface 1211, and the second side surface 1222 has the same shape and size as the first side surface 1212.

[0071] The notch 132 of the second side end surface 122 is formed by the second upper inclined surface 1221. In other words, the notch 132 of the second side end surface 122 has a so-called chamfered corner (corner) on the negative side in the X-axis direction and the positive side in the Z-axis direction of the container 120.

[0072] In addition, in this container 120, both end faces opposing each other in the Y-axis direction are long side faces 123. Each long side face 123 is a flat surface that is parallel to the XZ plane and elongated in the X-axis direction, and both end portions in the X-axis direction have shapes corresponding to the first side end face portion 121 and the second side end face portion 122.

[0073] Of the two end faces of the container 120 in the Z-axis direction, the end face on the positive side in the Z-axis direction is a top surface 124 , and the end face on the negative side in the Z-axis direction is a bottom surface 125 .

[0074] The top surface 124 is a rectangular flat surface parallel to the XY plane and elongated in the X-axis direction, connecting the upper end of the first upper inclined surface 1211 of the first side end surface portion 121 and the upper end of the second upper inclined surface 1221 of the second side end surface portion 122. The bottom surface 125 is a rectangular flat surface parallel to the XY plane and elongated in the X-axis direction, connecting the lower end of the first side surface 1212 of the first side end surface portion 121 and the lower end of the second side surface 1222 of the second side end surface portion 122.

[0075] The container body 135 has a pair of long sides 123, a first side surface 1212, a second side surface 1222, and a bottom surface 125, and the container 120 of the energy storage element 10 is formed by assembling the lid body 136 to the container body 135. The lid body 136 also has a first upper inclined surface 1211, a second upper inclined surface 1221, and a top surface 124. In this embodiment, the surface (outer surface) of the container 120 is covered with an insulating member such as an insulating film to ensure insulation from adjacent energy storage elements 10 in the energy storage element group 3.

[0076] Specifically, the container body 135 has flat long side wall portions with long sides 123 at both ends in the Y-axis direction, rectangular short side wall portions with first side 1212 or second side 1222 at both ends in the X-axis direction, and a rectangular bottom wall portion with a bottom surface 125 at the negative end in the Z-axis direction.

[0077] The lid 136 is formed by bending both ends of a strip-shaped member obliquely. Specifically, the lid 136 has a rectangular plate-shaped inclined wall portion with a first upper inclined surface 1211 at the end on the positive side in the X-axis direction, and a rectangular plate-shaped inclined wall portion with a second upper inclined surface 1221 at the end on the negative side in the X-axis direction. The lid 136 also has a rectangular plate-shaped top wall portion with a top surface 124 at the end on the positive side in the Z-axis direction.

[0078] With this configuration, the container 120 is structured such that the electrode body 110 and the like are housed inside the container body 135, and then the container body 135 and the lid 136 are joined by welding or the like, thereby sealing the interior (housing space S). At this time, in order to prevent a short circuit due to contact between the electrode body 110 and the container body 135 or the lid 136, the electrode body 110 and the like are housed inside the container body 135 after being wrapped in a resin film or the like.

[0079] In this container 120, the dimension in the X-axis direction of the top wall portion (top surface 124) is the same as or approximately the same as the dimension in the X-axis direction of the main body portion 111 of the electrode body 110, and the distance in the Z-axis direction between the top wall portion and the bottom wall portion is the same as or approximately the same as the dimension in the Z-axis direction of the main body portion 111 of the electrode body 110. Therefore, in the electrode body 110 accommodated in the container 120 (more specifically, within the accommodation space S of the container 120), the positive end of the main body portion 111 in the Z-axis direction abuts against the top wall portion of the container 120, and the negative end of the main body portion 111 in the Z-axis direction abuts against the bottom wall portion of the container 120.

[0080] The material of the container 120 (container body 135 and lid 136) configured as above is not limited, but is preferably a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0081] Although not shown here, the lid 136 has a liquid injection portion, which is a portion for injecting an electrolyte into the container 120 when manufacturing the energy storage device 10.

[0082] Each of the pair of electrode terminals 140 (positive electrode terminal 140A and negative electrode terminal 140B) is a member that is electrically connected to the electrode body 110 via the current collector 170. The electrode terminals 140 are metal members that conduct electricity stored in the electrode body 110 to the external space of the energy storage element 10 and introduce electricity into the energy storage element 10 to store electricity in the electrode body 110. The material of the electrode terminals 140 is not limited, but the electrode terminals 140 (positive electrode terminal 140A and negative electrode terminal 140B) are formed of a conductive member such as aluminum, an aluminum alloy, copper, or a copper alloy, for example. The electrode terminals 140 are connected (joined) to the current collector 170 by crimping, welding, or the like, and are attached to the lid body 136.

[0083] Specifically, each electrode terminal 140 has a terminal body 141 disposed outside the container 120, and a shaft 145 protruding from the terminal body 141 and extending to the interior (into the accommodation space S) of the container 120. The electrode terminals 140 of this embodiment are disposed in the notches 131 and 132 (i.e., the first upper inclined surface 1211 and the second upper inclined surface 1221) of the container 120, respectively.

[0084] The terminal body 141 is provided on the first upper inclined surface 1211 (or the second upper inclined surface 1221). The terminal body 141 of this embodiment is a rectangular plate when viewed from the normal direction. The terminal body 141 is located within a projection area of ​​the first upper inclined surface 1211 (or the second upper inclined surface 1221) in the Z-axis direction and within a projection area of ​​the first upper inclined surface 1211 (or the second upper inclined surface 1221) in the X-axis direction. That is, the terminal body 141 is located within the cutout regions R1 and R2 of the container 120. The cutout regions R1 and R2 in this embodiment are the regions surrounded by the first upper inclined surface 1211 (or the second upper inclined surface 1221) and the two-dot chain line L1 in FIGS. 3 and 6 .

[0085] The terminal body 141 has a welding surface 141WS provided on the first upper inclined surface 1211 (or the second upper inclined surface 1221) on the surface of the terminal body 141. In other words, the terminal body 141 has the welding surface 141WS on the surface opposite to the surface on which the shaft portion 145 of the electrode terminal 140 is formed (the surface of the electrode terminal 140 that contacts the recess 150a of the outer gasket 150, which will be described later).

[0086] The shaft 145 extends into the container 120 through a through-hole 1211a (or 1221a) that penetrates in the Z-axis direction at a position corresponding to the first upper inclined surface 1211 (or the second upper inclined surface 1221) of the lid 136. The shaft 145 is connected (joined) to the current collector 170 by being crimped while passing through the external gasket 150, the lid 136, the internal gasket 160, and the current collector 170 in that order.

[0087] Each of the pair of external gaskets 150 is disposed between the container 120 and the electrode terminal 140 (more specifically, the terminal main body 141) to provide insulation between the container 120 and the electrode terminal 140. Each of the pair of external gaskets 150 also provides a seal between the peripheral edge of the through-hole 1211a (or 1221a) of the container 120 and the shaft portion 145 of the electrode terminal 140.

[0088] This external gasket 150 is 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 made by adding a filler to any of these.

[0089] Specifically, the external gasket 150 is a plate-like member sandwiched between the first upper inclined surface 1211 (or the second upper inclined surface 1221) and the terminal body 141. Its rectangular shape corresponds to the terminal body 141 when viewed in the normal direction of the terminal body 141. The external gasket 150 has a recess 150a into which the terminal body 141 fits. The recess 150a is formed on the surface opposite the first upper inclined surface 1211 (or the second upper inclined surface 1221) in the normal direction of the terminal body 141, and the depth of the recess 150a is smaller than the thickness of the terminal body 141. As a result, the terminal body 141 protrudes from the external gasket 150 (more specifically, from the periphery of the recess 150a) when viewed in the Y-axis direction (see FIG. 6 ). The external gasket 150 also has a through-hole 150b at a position corresponding to the shaft 145 of the electrode terminal 140.

[0090] Each of the pair of internal gaskets 160 is disposed between the container 120 and the current collector 170 to provide insulation between the container 120 and the current collector 170. Each of the pair of internal gaskets 160 also provides a seal between the peripheral edge of the through-hole 1211a (or 1221a) of the container 120 and the shaft portion 145 of the electrode terminal 140.

[0091] Like the external gasket 150, the internal gasket 160 is 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 containing any of these with a filler added thereto.

[0092] Each of the pair of collectors 170 is arranged one on each side of the electrode body 110 in the X-axis direction, and is a component that connects (joins) the electrode body 110 and the electrode terminal 140 to establish electrical conductivity between the electrode body 110 and the electrode terminal 140.

[0093] Specifically, the current collector 170 has a first joint portion 171 that is connected (joined) to the tab portion 112 of the electrode body 110 by welding, crimping, or the like, a second joint portion 172 that is connected (joined) to the electrode terminal 140 by crimping, welding, or the like, and a connection portion 173 that connects the first joint portion 171 and the second joint portion 172. The first joint portion 171, the second joint portion 172, and the connection portion 173 are each a flat plate-like portion, and are formed by bending a single piece of sheet metal.

[0094] The tab portion 112 of the electrode assembly 110 is stacked in the Y-axis direction and has a tip that protrudes from the main body portion 111 in the X-axis direction, while the first bonding portion 171 that is bonded to the tab portion 112 is a plate-shaped member that extends in the YZ plane. Therefore, if the tip of the tab portion 112 and the first bonding portion 171 are simply in contact with each other in the X-axis direction, it is difficult to bond the tab portion 112 and the first bonding portion 171. Therefore, in this embodiment, the tab portion 112 of the electrode assembly 110 is bent in the Y-axis direction and bonded to the current collector 170. This ensures that the tab portion 112 and the first bonding portion 171 are reliably bonded, and also enables the electrode assembly 110 and the current collector 170 to be stored compactly inside the container 120.

[0095] The material of the current collector 170 is not limited, but for example, the positive current collector 170A is formed from a conductive material such as aluminum or an aluminum alloy, similar to the positive current collector foil 1131 of the electrode body 110, and the negative current collector 170B is formed from a conductive material such as copper or a copper alloy, similar to the negative current collector foil 1141 of the electrode body 110.

[0096] The energy storage elements 10 configured as described above are arranged in the energy storage element group 3 in the Y-axis direction such that the corresponding electrode terminals 140 of adjacent energy storage elements 10 (i.e., adjacent electrode terminals 140) have different polarities. That is, the multiple energy storage elements 10 are arranged in the Y-axis direction with both ends in the X-axis direction alternately inverted. At this time, the long side surfaces 123 of adjacent energy storage elements 10 face each other. Furthermore, at both ends in the X-axis direction of the energy storage element group 3, the notched portions 131, 132 of each energy storage element 10 are arranged alternately in the Y-axis direction.

[0097] The energy storage element group 3 is accommodated in the accommodation space S of the case 20 with the first side surface 1212, the second side surface 1222, the top surface 124, and the bottom surface 125 of each energy storage element 10 included in the energy storage element group 3 in contact with the corresponding cooling surfaces 20CS of the case 20 (in the example of this embodiment, the second side wall 232, the fourth side wall 234, the bottom wall 22, and the inner surfaces 20S of the case lid 25 of the case 20) (see FIG. 7 ). Furthermore, the energy storage element group 3 is accommodated in the accommodation space S of the case 20 with the outer long side surfaces 123 of each energy storage element 10 arranged at both ends in the Y-axis direction in contact with the corresponding inner surfaces 20S of the case 20 (in the example of this embodiment, the inner surfaces 20S of the first side wall 231 and the third side wall 233).

[0098] In this way, the storage element group 3 is accommodated in the case 20 so that each surface (first side surface 1212, second side surface 1222, top surface 124, bottom surface 125) of each storage element 10 constituting the storage element group 3 contacts the corresponding inner surface 20S of the case 20, thereby forming a first space S1 at the corner on the positive side of the X-axis direction and the positive side of the Z-axis direction within the case 20, and a second space S2 at the corner on the negative side of the X-axis direction and the positive side of the Z-axis direction within the case 20 (see Figure 7).

[0099] Each of the first space S1 and the second space S2 extends in the Y-axis direction from the inner surface 20S of the first side wall 231 to the inner surface 20S of the third side wall 233 inside the case 20. The bus bars 30 are arranged in the first space S1 and the second space S2.

[0100] Each of the plurality of bus bars 30 electrically connects the corresponding electrode terminals 140 of adjacent energy storage elements 10 (more specifically, the positive electrode terminals 140A and the negative electrode terminals 140B of adjacent energy storage elements 10), thereby connecting the plurality of energy storage elements 10 in series in the energy storage element group 3. The bus bars 30 are formed from a conductive metal member such as aluminum, an aluminum alloy, copper, a copper alloy, or nickel, or a combination thereof, or a conductive member other than a metal.

[0101] Specifically, the bus bar 30 is a plate-like portion that extends along the first upper inclined surface 1211 (or the second upper inclined surface 1221) and is elongated in the Y-axis direction. The dimension of the bus bar 30 in the Y-axis direction is such that the bus bar 30 overlaps with both of the two terminal main bodies 141 that are adjacent to each other in the Y-axis direction in the energy storage element group 3. In other words, the bus bar 30 is disposed so as to cover the surfaces of the terminal main bodies 141 of the two energy storage elements that are adjacent to each other in the Y-axis direction, at a position where the bus bar 30 straddles the terminal main bodies 141. The bus bar 30 may completely cover the surfaces of the terminal main bodies 141, or may only partially cover the surfaces of the terminal main bodies 141, leaving part of the surfaces of the terminal main bodies 141 exposed.

[0102] Each bus bar 30 is welded to the welding surfaces 141WS of the terminal main bodies 141 of two corresponding electrode terminals 140 (i.e., the positive terminal 140A and the negative terminal 140B adjacent in the Y-axis direction) of adjacent energy storage elements 10 in the energy storage element group 3, thereby connecting (establishing electrical continuity between) these two electrode terminals 140A, 140B. When the energy storage element group 3 is viewed from the Y-axis direction, each bus bar 30 is located within a first space S1 or a second space S2 (i.e., cutout regions R1, R2 continuous in the Y-axis direction) (see FIG. 7 ). Note that, in the present embodiment, the bus bar 30 has a plate-like shape, and the surfaces of the electrode terminals 140A, 140B are also illustrated as being flat, but the present invention is not limited to this configuration. At the joints between the bus bar 30 and the electrode terminals 140A, 140B, the bus bar 30 may have holes, and the electrode terminals 140A, 140B may have protrusions that fit into the holes in the bus bar 30. Furthermore, the electrode terminals 140A, 140B may have bolt portions and nut portions, and the nut portions may be screwed onto the bolt portions with the bolt portions inserted into the holes in the bus bar 30 (i.e., the bus bar 30 may be fastened by the bolt portions and the nut portions).

[0103] In addition, in the energy storage device 1 of this embodiment, the positive terminal 140A of the energy storage element 10 at the positive end in the Y-axis direction in the energy storage element group 3 is connected to the first general terminal 235 via a general terminal wire, and the negative terminal 140B of the energy storage element 10 at the negative end in the Y-axis direction in the energy storage element group 3 is connected to the second general terminal 236 via a general terminal wire.

[0104] The energy storage element 10 included in the energy storage device 1 described above includes an electrode assembly 110 in which a plurality of electrode plates 113, 114 are stacked, a container 120 that houses the electrode assembly 110, and a pair of electrode terminals 140 that are electrically connected to the electrode assembly 110. When viewed from a Y direction (first direction) that is a predetermined horizontal direction, the container 120 has a rectangular shape that is elongated in an X axis direction (second direction) that is perpendicular to the Y axis direction and is horizontal, and has notches in at least two of the four corners of the rectangle on one side in the vertical direction, and each of the notches is configured by a first upper inclined surface (terminal placement surface) 1211 or a second upper inclined surface (terminal placement surface) 1221 that extends along an inclination direction that intersects with each of the short sides and long sides of the rectangle when viewed from the Y axis direction. Each of the electrode terminals 140 is provided on the first upper inclined surface (terminal placement surface) 1211 or the second upper inclined surface (terminal placement surface) 1221.

[0105] According to the energy storage element 10 of one embodiment of the present invention, the electrode terminals 140 are arranged along the first upper inclined surface 1211 or the second upper inclined surface 1221 provided at two corners of the rectangular shape when the container 120 is viewed from the Y-axis direction, thereby reducing the dead space caused by the protrusion of the electrode terminals 140 when the energy storage element 10 is housed in the case portion 2 (see Figure 7), thereby improving the energy density of the energy storage device 1 when the energy storage element 10 is housed in the case portion 2.

[0106] Furthermore, in the energy storage device 1 of this embodiment, the electrode terminals 140 are located within a projection area of ​​the first upper inclined surface (terminal arrangement surface) 1211 or the second upper inclined surface (terminal arrangement surface) 1221 in the Z-axis direction, and within a projection area of ​​the first upper inclined surface 1211 or the second upper inclined surface 1221 in the X-axis direction (i.e., within the cutout areas R1 and R2). Therefore, when multiple energy storage elements 10 are arranged in the Y-axis direction, contact between the electrode terminals 140 of adjacent energy storage elements 10 is suppressed. Furthermore, when multiple energy storage elements 10 are arranged in the Y-axis direction, protrusion of the electrode terminals 140 of each energy storage element 10 in the Z-axis direction and protrusion of the electrode terminals 140 from both end edge positions of each energy storage element 10 in the X-axis direction are also suppressed when viewed from the Y-axis direction.

[0107] In addition, the energy storage device 1 of this embodiment comprises a plurality of energy storage elements 10 arranged in the Y-axis direction and at least one bus bar 30 that connects corresponding electrode terminals 140 of at least adjacent energy storage elements 10, and the corresponding first upper inclined surfaces (terminal arrangement surfaces) 1211 and second upper inclined surfaces (terminal arrangement surfaces) 1221 of adjacent energy storage elements 10 are arranged in the Y-axis direction along a virtual plane that extends in the inclination direction (the direction along the first upper inclined surface 1211 and the second upper inclined surface 1221 when viewed from the Y-axis direction) and the Y-axis direction.

[0108] In this way, in the energy storage device 1 of this embodiment, the electrode terminals 140 are arranged along the first upper inclined surfaces 1211 or the second upper inclined surfaces 1221 provided at two corners of the rectangular shape when the container 120 is viewed from the Y-axis direction, thereby reducing dead space caused by the protrusion of the electrode terminals 140 when multiple energy storage elements 10 are housed in the case portion 2. This makes it possible to improve the energy density of the energy storage device 1.

[0109] The energy storage device 1 of this embodiment also includes a case portion (element container) 2 in which at least one of a plurality of inner surfaces 20S that define the internal storage space S is a cooling surface 20CS, and the case portion 2 accommodates an energy storage element group 3 including a plurality of energy storage elements 10 and at least one bus bar 30 such that the energy storage element group 3 is in contact with the cooling surface 20CS. Therefore, the energy storage element group 3 accommodated in the case portion 2 is cooled by being in contact with the cooling surface 20CS, and thereby a temperature rise in the energy storage element group 3 during charging and discharging is suppressed.

[0110] Furthermore, in the energy storage device 1 of this embodiment, the busbar 30 is located within a projection area of ​​the first upper inclined surface (terminal arrangement surface) 1211 or the second upper inclined surface (terminal arrangement surface) 1221 in the Z-axis direction (vertical direction) and within a projection area of ​​the first upper inclined surface 1211 or the second upper inclined surface 1221 in the second direction (i.e., within the cutout areas R1 and R2) when viewed from the Y-axis direction. Therefore, in the energy storage element group 3, the busbar 30 does not protrude outward in the X-axis direction or in the Z-axis direction when viewed from the Y-axis direction. This makes it possible to prevent the generation of dead space in the storage space S of the case 2 due to the protrusion of the busbar 30 (see, for example, FIG. 7 ). On the other hand, if the storage space S is excessively large, this leads to a reduction in the effective electrode area of ​​the electrode body 110 in the energy storage element 10, leading to a reduction in the energy density of the energy storage device 1. Therefore, it is important to design the storage space S to an appropriate size. The appropriate size of the storage space S varies depending on the dimensions and capacity of the energy storage element 10, the dimensions of the electrode terminal 140, the dimensions of the bus bar 30, and the like.

[0111] Furthermore, when a plurality of energy storage elements 10 are housed in the case portion 2, a laser can be applied from the top surfaces of the plurality of energy storage elements 10 when laser welding the electrode terminals 140 of the energy storage elements 10 to the bus bar 30. This simplifies the bus bar welding process for the plurality of energy storage elements 10, while achieving a low-resistance connection structure in which the contact area between the bus bar 30 and the electrode terminals 140 and the area of ​​the bus bar 30 are large.

[0112] The energy storage element and energy storage device of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, or part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, part of the configuration of one embodiment can be deleted.

[0113] In the energy storage device 1 of the above embodiment, the energy storage elements 10 constituting the energy storage element group 3 are connected in series by the bus bars 30, but the present invention is not limited to this configuration. The energy storage elements 10 constituting the energy storage element group 3 may be connected in parallel by the bus bars 30.

[0114] Specifically, it is also possible to make parallel connections within the storage element group 3, and in this case, the corresponding electrode terminals 140 of adjacent storage elements 10 (i.e., adjacent electrode terminals 140) with the same polarity may be arranged in the Y-axis direction, and the adjacent storage elements 10 may be joined with a bus bar 30.

[0115] In this case, the bus bar 30 connection between the energy storage elements 10 may not only be between adjacent energy storage elements 10, but may also be between a plurality of energy storage elements 10 connected by a single bus bar 30.

[0116] In addition, although the present embodiment illustrates a case in which only one energy storage element group 3 is housed in the case 20, a plurality of energy storage element groups 3 may be housed. Also, a partition structure may be provided between the plurality of energy storage element groups 3. Furthermore, with regard to the electrical connection between the plurality of battery element groups 3, the plurality of battery element groups 3 may be electrically connected in series or in parallel.

[0117] In the energy storage element 10 of the above embodiment, the notches 131, 132 in which the electrode terminals 140 are arranged are provided in the upper two of the four corners when the container 120 is viewed from the Y-axis direction, but this configuration is not limiting. The notches 131, 132 in which the electrode terminals 140 are arranged may also be provided in the lower two of the four corners when the container 120 is viewed from the Y-axis direction.

[0118] Furthermore, in the energy storage element 10 of the above embodiment, the notch 131 on the positive side in the X-axis direction and the notch 132 on the negative side have the same shape and size, but they may be different. That is, the inclination angle of the first upper inclined surface 1211 and the second upper inclined surface 1221 with respect to the Z-axis direction may be slightly different. Specifically, the difference in the inclination angle may be such that it does not cause any problems when the electrode terminals 140 are busbar-welded.

[0119] Furthermore, in the energy storage element 10 of the above embodiment, the shape of the container 120 as viewed in the X-axis direction is rectangular, but this configuration is not limited thereto. For example, the container 120A may be oval as viewed in the X-axis direction, as shown in FIG. 8 . That is, the container 120A may have a shape based on a flat, oval cylinder. With this configuration, the container 120A is shaped to conform to the outer surface of the electrode body 110, which reduces dead space (excess space) inside the container 120A compared to a rectangular container, thereby improving the energy density inside the container 120A of the energy storage element 10A.

[0120] Specifically, in the container 120A, the top surface 124A has an arc shape that is convex upward when viewed from the X-axis direction, and the bottom surface 125A has an arc shape that is convex downward when viewed from the X-axis direction. Furthermore, the container 120 is not limited to a rectangular or oval shape when viewed from the X-axis direction. The container 120 may have a circular or polygonal shape when viewed from the X-axis direction. That is, the container 120 only needs to have a rectangular shape that is elongated in the X-axis direction when viewed from the Y-axis direction and have notches at two of its four corners on one side in the Z-axis direction.

[0121] Furthermore, there are no limitations on the specific shape of each terminal body 141. While each terminal body 141 in the above embodiment has a rectangular shape when viewed from the normal direction of the welding surface 141WS, it may also have, for example, a circular, oval, or elliptical shape.

[0122] In addition, in the storage element group 3 of the above embodiment, multiple storage elements 10 are arranged so that adjacent storage elements 10 are in contact with each other, but spacers, insulating members, etc. may also be arranged between adjacent storage elements 10 in the Y-axis direction.

[0123] Furthermore, in the above embodiment, the case body 21 is a bottomed, rectangular cylindrical member having a height in the Z-axis direction sufficient to accommodate the energy storage device 10 and an opening 21A, and the case lid 25 is a rectangular, plate-like member extending in the X-axis and Y-axis directions. However, this embodiment is not limited to this. The case lid 25 does not simply have to be a plate-like member made of a single plate. Instead, it can have four side walls continuously arranged circumferentially along the periphery, like the case body 21, to form a bottomed, rectangular cylindrical member with its bottom located opposite the case body 21 in the Z-axis direction. In other words, the case lid 25 can also be a square-shaped (box-shaped) member with a top surface that is a plate-like member located on the positive side of the Z-axis direction, side walls arranged along the Z-axis from this top surface, and an opening on the negative side of the Z-axis direction.

[0124] By using the above-described modified case lid and simultaneously lowering the height of the side walls of the case body 21 compared to the configuration shown in FIG. 2 , it is possible to combine the case body 21 and the modified case lid to form the case 20 as an upper case and a lower case. The height of the inner walls of the first to fourth side walls 231 to 234 of the case body 21 in the Z-axis direction shown in FIG. 2 is half the height of the energy storage device 10 in the Z-axis direction, allowing the case body 21 to accommodate the lower half of the energy storage device 10 in the Z-axis direction. Furthermore, the height of the inner walls of the side walls in the modified case lid is half the height of the energy storage device 10 in the Z-axis direction, allowing the case lid to accommodate the upper half of the energy storage device 10 in the Z-axis direction. It is also possible to appropriately select one and two-thirds of the overall height in the Z-axis direction shown in FIG. 2 rather than dividing the height exactly in half. In this case, it is also possible to accommodate the terminal portion 140 of the energy storage device 10 and the connection portion of the bus bar 30 in the internal space of the modified case lid (upper case). When an upper case and a lower case having such a structure are used, when welding the bus bar 30 to the terminal portion 140 of the energy storage element 10, the side walls of the case main body 21 (lower case) do not interfere with the terminal portion 140 and the bus bar 30, thereby improving the workability of welding the bus bar 30.

[0125] In the above embodiment, the refrigerant pipes 26 are provided with one line on each side of the case 20, and four lines are arranged on the four sides of the case 20, but this embodiment is not limited to this. The refrigerant pipes 26 may be bent from the first side to the second side of the case 20, so that they are provided across two sides of the case 20.

[0126] 1...Energy storage device, 2...Case portion (element container), 20...Case, 20CS...Cooling surface, 20S...Inner surface, 21...Case main body, 21A...Opening, 22...Bottom wall, 23...Peripheral wall, 231...First side wall, 232...Second side wall, 233...Third side wall, 234...Fourth side wall, 235...First main terminal, 236...Second main terminal, 25...Case lid body, 26...Refrigerant tube, 3...Energy storage element group, 30...Bus bar, 10, 10A...Energy storage element, 110...Electrode body, 111...Main body portion, 1111...Curved portion, 1112...flat portion, 112...tab portion, 112a...positive electrode tab portion, 112b...negative electrode tab portion, 113...positive electrode plate (electrode plate), 1131...positive electrode current collecting foil, 1132...positive electrode active material layer, 1133...projecting piece, 114...negative electrode plate (electrode plate), 1141...negative electrode current collecting foil, 1142...negative electrode active material layer, 1143...projecting piece, 115, 116...separator, 120, 120A...container, 121...first side end surface portion, 1211...first upper inclined surface (terminal arrangement surface), 1211a...through hole, 121 2...first side surface, 122...second side end surface portion, 1221...second upper inclined surface (terminal arrangement surface), 1222...second side surface, 123...long side surface, 124, 124A...top surface, 125, 125A...bottom surface, 131, 132...notch portion, 135...container body, 136...lid body, 140...electrode terminal, 140A...positive electrode terminal, 140B...negative electrode terminal, 141...terminal body portion, 141WS...welding surface, 145...shaft portion, 150...external gasket, 150a...recess, 150b...through hole, 160 ...internal gasket, 170...current collector, 170A...positive electrode current collector, 170B...negative electrode current collector, 171...first joint, 172...second joint, 173...connection, 500...secondary battery, 501...battery case, 502...case body, 503...lid, 504...positive electrode terminal, 505...negative electrode terminal, 506...element container, 507...energy storage device, B...bus bar, DS...dead space, L...winding axis, R1, R2...notched area, S...accommodation space, S1...first space, S2...second space

Claims

1. An energy storage element comprising: an electrode assembly formed by stacking a plurality of electrode plates; a container that houses the electrode assembly; and a pair of electrode terminals that are electrically connected to the electrode assembly, wherein the container has a rectangular shape that, when viewed from a first direction that is a predetermined horizontal direction, is elongated in a second horizontal direction that is perpendicular to the first direction, and at least two of the four corners of the rectangle have cutout shapes at one side in the vertical direction, each of the cutout shapes being formed by a terminal arrangement surface that is arranged along an inclined direction that intersects with each of the long side of the rectangle as viewed from the first direction on one side in the vertical direction and each of the short side of the rectangle on one side in the second direction or the short side on the other side in the second direction, and each of the electrode terminals is provided on the terminal arrangement surface.

2. The energy storage element according to claim 1, wherein the electrode terminals are located within a projection area of ​​the terminal arrangement surface in the vertical direction and within a projection area of ​​the terminal arrangement surface in the second direction.

3. The energy storage element described in claim 1, wherein the electrode body is constructed by winding the electrode plates so that they have an elliptical shape when viewed from the second direction, and the container has an elliptical shape corresponding to the electrode body when viewed from the second direction.

4. An energy storage device comprising: a plurality of energy storage elements according to any one of claims 1 to 3 lined up in the first direction; and at least one bus bar that electrically connects the corresponding electrode terminals of at least adjacent energy storage elements, wherein the corresponding terminal arrangement surfaces of the adjacent energy storage elements are lined up in the first direction along a common imaginary plane that extends in the tilt direction and the first direction.

5. The energy storage device according to claim 4, comprising an element container in which at least one of a plurality of inner surfaces defining an internal storage space is a cooling surface, the element container housing a group of energy storage elements including the plurality of energy storage elements and the at least one bus bar so that the group of energy storage elements is in contact with the cooling surface.

6. The energy storage device according to claim 5, wherein the bus bar is located within a projection area of ​​the terminal arrangement surface in the vertical direction and within a projection area of ​​the terminal arrangement surface in the second direction when viewed from the first direction.

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