Power storage device

Abstract

To provide a power storage device which has improved safety by a simple configuration.SOLUTION: A power storage device 1 comprises: a power storage element unit 50 including power storage elements 100 and bus bars 60 which are disposed on the lateral sides of the power storage elements 100 in the positive direction of the Z-axis and are electrically connected to the power storage elements 100; and bus bar covers 70. The bus bar covers 70 are a series of members which, when viewed from the positive direction of the Z-axis, cover the bus bars 60 and expose a region of the power storage element unit 50 where the bus bars 60 are not located. The bus bar covers 70 have first fixed parts 71 which are portions to be fixed to the power storage element unit 50. The first fixed parts 71 are provided at positions, on the bus bar covers 70, between both ends in the X-axis direction and also between both ends in the Y-axis direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an energy storage device including an energy storage element and a bus bar. [Background technology]

[0002] Conventionally, there has been a power storage device including a power storage element and a bus bar connected to the power storage element. Patent Document 1 discloses a bus bar module including a case having an opening, a bus bar housed in the opening of the case, a cover covering the opening, and a locking mechanism for fixing the cover to the case. In this bus bar module, the locking mechanism includes a locking portion that protrudes from the top wall of the cover and has a locking claw at its tip, and a lock receiving portion that is provided in the case and has a locking hole formed therein. A predetermined area of the top wall of the cover near the locking portion is provided with a flexible deformation portion that is more flexible than a portion outside the predetermined area. As a result, after the locking claw engages with the locking hole, the restoring force of the flexible deformation portion acts on the locking claw in a direction that pulls the locking hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-77566 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional busbar module, the busbar cover has a cover that covers the busbars. The busbar cover can be attached to the case by engaging the latches of the cover with latch holes in the case where the busbars are arranged. However, the conventional busbar cover is large enough to cover the entire structure (energy storage element unit) consisting of multiple busbars, the case, and multiple energy storage elements underneath, i.e., it has a relatively large rectangular shape in a plan view. Because misalignment of the busbar cover increases the possibility of contact (conduction) between the busbars and other components, such a relatively large busbar cover needs to have portions that are fixed to the energy storage element unit, for example, at both ends in the short direction in a plan view. Furthermore, to prevent the main body of the busbar cover from obscuring the connection points between the busbar cover and the energy storage element unit, a measure such as providing a notch in the main body of the busbar cover is required. As a result, the structure of the busbar cover becomes complex, which, for example, makes it difficult to improve manufacturing efficiency or increases manufacturing costs.

[0005] The present invention was made by the present inventors by focusing on the above-mentioned problem, and has an object to provide a power storage device with a simple configuration and improved safety. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an energy storage device comprising: an energy storage element unit including an energy storage element; and a bus bar arranged to the side of the energy storage element in a first direction and electrically connected to the energy storage element; and a bus bar cover which is a series of members that covers the bus bar when viewed from the first direction and exposes an area of the energy storage element unit where the bus bar is not arranged, wherein the bus bar cover has a first fixed portion which is a part that is fixed to the energy storage element unit, and the first fixed portion is provided at a position between both end portions of the bus bar cover in a second direction perpendicular to the first direction and between both end portions in a third direction perpendicular to the first direction and the second direction.

[0007] This configuration allows the busbar cover to be fixed at a position other than the end of the busbar cover in a plan view, for example. Therefore, for example, a single first fixed portion effectively securely fixes the busbar cover. Therefore, for example, the busbar cover is less likely to shift due to vibration or impact, resulting in electrical conduction between the busbar and other conductive members. Furthermore, the busbar cover can be realized using a member of a size and shape that substantially covers only the area where the busbar is arranged. This allows for the miniaturization of the energy storage element unit in which the busbar cover is arranged, or the amount of material required to form the busbar cover to be reduced. Furthermore, because the busbar cover does not cover the entire energy storage element unit when viewed from the first direction (plan view), for example, the connection points between the first fixed portion and the energy storage element unit are relatively easy to see. Therefore, the busbar cover can be easily positioned on the energy storage element unit. As such, the energy storage device according to this aspect is an energy storage device with improved safety despite its simple configuration.

[0008] The energy storage element unit may include a bus bar holder that holds the bus bar, and the bus bar holder may include a fixing portion that fixes the first fixed portion.

[0009] According to this configuration, the first fixing portion and the first fixed portion are combined on the busbar holder and the busbar cover, which are made of, for example, electrically insulating resin. This allows for a high degree of freedom in the size and shape of the first fixing portion and the first fixed portion. This makes it easy to perform the fixing operation or to form fixing portions and fixed portions that can obtain a large fixing force. In other words, the busbar cover can be more reliably fixed to the busbar holder.

[0010] The busbar cover may further have a second fixed portion, which is a portion fixed to the energy storage element unit, at at least one of both end portions in the second direction, which is the longitudinal direction of the busbar cover.

[0011] According to this configuration, the bus bar cover that is elongated in the second direction is fixed at its intermediate portion in the longitudinal direction (a portion other than both ends) and also at its end portions in the longitudinal direction. In this way, the bus bar cover is fixed at multiple fixing portions, which suppresses misalignment or deformation due to vibration or impact, and thereby further improves the safety of the energy storage device.

[0012] The energy storage element unit may further include a spacer that is arranged in a position facing the energy storage element in the second direction and that is aligned with the first fixed portion in the first direction.

[0013] According to this configuration, the fixed portion is provided by utilizing the space above the spacer, which is equivalent to the thickness of the spacer. This makes it easy to ensure work space for fixation, such as heat staking, fastening, or press-fitting, and also makes it easy to obtain sufficient fixation force. Furthermore, if the size of the fixed portion in the second direction is relatively large to ensure sufficient fixation force, for example, a thicker spacer can be disposed by utilizing the space below the fixed portion. This improves the impact resistance of the energy storage device or improves the thermal insulation performance between the energy storage elements, thereby further improving the safety of the energy storage device.

[0014] The bus bars may be arranged in a row in the second direction, and the first fixed portion may be arranged between two adjacent bus bars when viewed from the first direction.

[0015] According to this configuration, for example, the first fixed portion, which is a part of the bus bar cover made of an insulating material, is positioned between two adjacent bus bars, and the first fixed portion can function as a portion that prevents direct electrical conduction between these bus bars. Furthermore, if two bus bars are spaced a relatively long distance apart from a safety perspective, it is possible to utilize that long distance to form the first fixed portion with a relatively large width in the second direction. This improves the fixing force of the bus bar cover by the first fixed portion, or simplifies the process of fixing the first fixed portion to the energy storage element unit (fixing process). [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a power storage device with a simple configuration and improved safety. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view showing the appearance of a power storage device according to an embodiment; [Figure 2] FIG. 2 is an exploded perspective view of the electricity storage device according to the embodiment. [Figure 3] FIG. 2 is a perspective view showing the appearance of an energy storage element and a spacer according to an embodiment. [Figure 4] 4 is a perspective view showing the structural relationship between an energy storage element unit and a bus bar cover according to the embodiment. FIG. [Figure 5] FIG. 2 is a perspective view showing the structural relationship between a bus bar holder and a bus bar cover according to the embodiment. [Figure 6] 10 is a plan view of the bus bar cover fixed to the bus bar holder according to the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, with reference to the drawings, a description will be given of an energy storage device according to an embodiment of the present invention (including its modified examples). Note that the embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, in each drawing, dimensions and the like are not strictly illustrated. Furthermore, in each drawing, the same or similar components are assigned the same reference numerals.

[0019] In the following description and drawings, the longitudinal direction of the exterior body of the energy storage device, the arrangement direction of multiple energy storage elements, or the opposing direction of the long side surfaces of the containers of the energy storage elements is defined as the X-axis direction. The lateral direction of the exterior body of the energy storage device, the opposing direction of the short side surfaces of the containers of the energy storage elements, or the arrangement direction of a pair of electrode terminals of one energy storage element is defined as the Y-axis direction. The arrangement direction of the main body and lid of the exterior body of the energy storage device, the arrangement direction of the bus bar holder and the energy storage element unit, or the up-down direction is defined as the Z-axis direction. The X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the mode of use, the Z-axis may not be the up-down direction; however, for convenience of explanation, the following description will be made assuming that the Z-axis direction is the up-down direction.

[0020] In the following description, 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. Furthermore, simply referring to the "X-axis direction" means either or both directions parallel to the X-axis. The same applies to terms related to the Y-axis and Z-axis.

[0021] Furthermore, expressions indicating relative directions or attitudes, such as "parallel" and "orthogonal," also include cases where the directions or attitudes are not strictly those. For example, "two directions are orthogonal" does not only mean that the two directions are completely orthogonal, but also means that the two directions are substantially orthogonal, i.e., there is a difference of, for example, a few percent.

[0022] (Embodiment) [1. General description of the power storage device] First, a schematic configuration of an energy storage device 1 according to an 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 of the energy storage device 1 according to the embodiment. FIG. 3 is a perspective view showing the appearance of an energy storage element 100 and a spacer 130 according to the embodiment. FIG. 4 is a perspective view showing the structural relationship between an energy storage element unit 50 according to the embodiment and a bus bar cover 70. FIG. 4 illustrates a state in which a plurality of bus bars 60 and a bus bar holder 30 have been separated from an energy storage element string 101 including a plurality of energy storage elements 100, and the bus bar cover 70 has been separated from the energy storage element unit 50. Furthermore, FIG. 4 does not illustrate an electrical device 40 arranged on the bus bar holder 30.

[0023] In addition to the components shown in FIG. 2 and subsequent figures, wiring and the like connected to the electrical device 40 are housed inside the exterior body 10, but illustration and description of these components will be omitted as appropriate.

[0024] The power storage device 1 is a device that can charge with electricity from an external source and discharge electricity to the outside, and in this embodiment has a substantially rectangular parallelepiped shape. The power storage device 1 is, for example, a battery module (battery assembly) used for power storage or power supply purposes. Specifically, the power storage device 1 is used as a battery for driving or starting the engine of a mobile object such as an automobile, motorcycle, personal watercraft, ship, 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 gasoline-powered 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 can also be used as a stationary battery for home or business use.

[0025] 1 and 2 , the energy storage device 1 includes an exterior body 10, and an energy storage element unit 50 and a bus bar cover 70 housed in the exterior body 10. In this embodiment, the energy storage device 1 is provided with two bus bar covers 70, and when describing these separately, the bus bar cover 70 on the negative Y-axis side will be referred to as bus bar cover 70A, and the bus bar cover 70 on the positive Y-axis side will be referred to as bus bar cover 70B. In this embodiment, the bus bar cover 70 will be described as a member attached to the energy storage element unit 50, but the bus bar cover 70 may also be treated as part of the energy storage element unit 50.

[0026] The exterior body 10 is a box-shaped (approximately rectangular parallelepiped) container (module case) that constitutes the housing of the energy storage device 1. In other words, the exterior body 10 is disposed outside the energy storage element unit 50 and the bus bar cover 70, fixing them in place and protecting them from impacts and the like. The exterior body 10 is formed of an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyether sulfone (PES), ABS resin, or a composite material thereof, or a metal with an insulating coating. The exterior body 10 thereby prevents the energy storage element unit 50 and the like from coming into contact with external metal members and the like. The exterior body 10 may be formed of a conductive material such as metal, as long as electrical insulation between the exterior body 10 and the energy storage element unit 50 and the like is maintained.

[0027] The exterior body 10 includes an exterior body main body 12 and a lid body 11. The exterior body main body 12 is a bottomed rectangular cylindrical housing with an opening 12a formed on the positive side of the Z axis, and houses the energy storage element unit 50 and other components. The lid body 11 is a rectangular member that closes the opening 12a of the exterior body main body 12. The lid body 11 is joined to the exterior body main body 12, preferably in an airtight or watertight manner, by adhesive, heat sealing, ultrasonic welding, laser welding, or the like. A pair of external terminals 13, which are a pair of module terminals on the positive and negative sides, are disposed on the lid body 11. The energy storage device 1 is charged with electricity from the outside and discharges electricity to the outside via the pair of external terminals 13. The external terminals 13 are formed of a conductive metal material, such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0028] The energy storage element unit 50 has an energy storage element 100, a bus bar 60 electrically connected to the energy storage element 100, and a bus bar holder 30 that holds the bus bar 60. In this embodiment, the bus bar holder 30 that holds the plurality of bus bars 60 is arranged on an energy storage element array 101 that is made up of a plurality of (specifically, eight) energy storage elements 100 and a plurality of spacers 130 and 135. A plurality of electric devices 40 and bus bars 65 connected to these electric devices 40 are arranged on the upper surface of the bus bar holder 30.

[0029] The energy storage element 100 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. As shown in FIG. 3 , the energy storage element 100 has a flat rectangular (square) container 110 and a pair of electrode terminals 120 (positive and negative) fixed to the container 110. The container 110 contains an electrode body, a current collector, an electrolyte, and the like (not shown). An example of the electrode body included in the energy storage element 100 is a wound-type electrode body formed by winding layers of positive and negative electrode plates with a separator sandwiched between them. Alternatively, the energy storage element 100 may be provided with a stack-type electrode body formed by stacking a plurality of flat electrode plates, or a bellows-type electrode body formed by folding electrode plates in a bellows shape.

[0030] The energy storage element 100 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 100 may not be a secondary battery, but may be a primary battery that can use stored electricity without the user having to charge it. The energy storage element 100 may be a battery that uses a solid electrolyte. The energy storage element 100 may be a pouch-type energy storage element. Furthermore, the shape of the energy storage element 100 is not limited to the above-mentioned rectangular shape, but may be other shapes such as a polygonal prism, a cylindrical shape, an elliptical cylindrical shape, or an oblong cylindrical shape.

[0031] In this embodiment, the container 110 has a pair of long side surfaces 110a, a pair of short side surfaces 110b, and a terminal arrangement surface 110c, as shown in Fig. 3. The terminal arrangement surface 110c is a surface on which the positive and negative electrode terminals 120 are arranged. In this embodiment, a gas release valve 105 is also arranged on the terminal arrangement surface 110c. The gas release valve 105 is a component that opens in response to an excessive increase in internal pressure of the container 110, thereby releasing gas inside the container 110 to the outside.

[0032] In the energy storage element array 101, the multiple energy storage elements 100 are aligned with their long side surfaces 110a facing the alignment direction (X-axis direction). In the multiple energy storage elements 100 aligned in this manner, one spacer 130 is arranged for every two energy storage elements 100, and spacers 135 are also arranged at both ends of the energy storage element array 101. The spacers 130 are, for example, components called intermediate spacers, and are arranged between two adjacent energy storage elements 100 as shown in FIG. 3. The spacers 130 electrically insulate the containers 110 of the two energy storage elements 100 from each other. The spacers 130 can also suppress heat conduction from one energy storage element 100 to the other energy storage element 100. The spacers 135 are, for example, components called end spacers, and protect the energy storage elements 100 at the ends of the aligned multiple energy storage elements 100 and electrically insulate the end energy storage elements 100 from other components. The energy storage element array 101 may be restrained in the arrangement direction of the energy storage elements 100 by a restraining member (not shown). In this case, even if the end plate of the restraining member is made of metal, the end plate and the energy storage element 100 adjacent to the end plate are electrically insulated by the spacer 135.

[0033] The bus bar holder 30 is a flat, rectangular insulating member that is disposed opposite the terminal arrangement surface 110c of the energy storage element 100 and that holds the plurality of bus bars 60 and the electrical devices 40. The bus bar holder 30 is formed, for example, from any electrically insulating resin material that can be used for the exterior body 10 described above.

[0034] As shown in FIG. 4 , the bus bar holder 30 has a plurality of bus bar openings 30a that expose portions of the bus bars 60 toward the energy storage elements 100. The bus bars 60 arranged in the bus bar openings 30a are positioned with respect to the electrode terminals 120 to be joined, and are joined to the electrode terminals 120 in this state by, for example, laser welding. In this embodiment, of the eight energy storage elements 100 included in the energy storage element unit 50, two adjacent energy storage elements 100 are connected in parallel by the bus bars 60. This forms four sets of parallel-connected energy storage elements 100. Furthermore, these sets of four energy storage elements 100 are connected in series by three bus bars 60. A bus bar 60 is joined to each of the total positive terminal 121 and the total negative terminal 122 of the energy storage element unit 50 that has the eight energy storage elements 100 electrically connected in this manner. In this embodiment, as shown in Fig. 4, the positive electrode terminals 120 of the two energy storage elements 100 at the ends in the positive direction of the X axis are the total positive terminals 121, and the negative electrode terminals 120 of the two energy storage elements 100 at the ends in the negative direction of the X axis are the total negative terminals 122. Note that the electrical connection mode of the eight energy storage elements 100 by the bus bars 60 is not limited to this, and for example, all eight energy storage elements 100 may be connected in series by a plurality of bus bars 60. Furthermore, the number of energy storage elements 100 included in the energy storage element unit 50 is not limited to eight. The number of energy storage elements 100 included in the energy storage element unit 50 may be one or more.

[0035] The electrical device 40 arranged on the bus bar holder 30 is electrically connected to the plurality of energy storage elements 100 included in the energy storage element unit 50, and is also electrically connected to the positive or negative external terminal 13 via a bus bar 65 (see FIG. 2). In this embodiment, as shown in FIG. 2, the electrical devices 41 and 42 are provided in the energy storage device 1 as the electrical devices 40 arranged on the bus bar holder 30.

[0036] The electrical device 42 is, for example, a control device called a BMU (Battery Management unit), which detects the voltage of each of the plurality of energy storage elements 100 and the temperature of the energy storage element unit 50, and controls the charging state of the plurality of energy storage elements 100. The electrical device 41 is, for example, a relay unit having an electromagnetic switch, and has the function of switching on and off charging or discharging of the energy storage device 1.

[0037] In the energy storage device 1 configured in this manner, the bus bars 60 joined to the electrode terminals 120 of the energy storage elements 100 are covered by bus bar covers 70. Specifically, as shown in Fig. 4, the two bus bars 60 on the negative Y-axis side are covered by bus bar covers 70A, and the three bus bars 60 on the positive Y-axis side are covered by bus bar covers 70B.

[0038] Like the exterior housing 10, the bus bar cover 70 is formed of an electrically insulating resin such as PC, PP, or PE, which substantially prevents electrical conduction between the bus bar 60 and other components arranged above the bus bar 60 (in the positive direction of the Z axis). In this embodiment, a first fixed portion 71 and a second fixed portion 72 of the bus bar cover 70 are fixed to a first fixing portion 31 and a second fixing portion 32 of the energy storage element unit 50, respectively. The fixing structure of the bus bar cover 70 to the energy storage element unit 50 will be described in detail below with reference to FIGS. 5 and 6 in addition to the above-mentioned FIG. 4.

[0039] [2. Busbar cover fixing structure] Fig. 5 is a perspective view showing the structural relationship between the busbar holder 30 and the busbar cover 70 according to the embodiment. Fig. 5 shows the busbar covers 70A and 70B separated from the busbar holder 30. Fig. 6 is a plan view of the busbar cover 70 fixed to the busbar holder 30 according to the embodiment.

[0040] As shown in FIGS. 4 to 6 , the busbar cover 70 is a continuous member (single component) formed in an elongated shape in the X-axis direction so as to cover the multiple busbars 60 lined up in the X-axis direction. The busbar cover 70 is formed in a size and shape that exposes the areas where no busbars 60 are arranged. In other words, when the energy storage element unit 50 is viewed from the positive direction of the Z-axis, only a portion of the energy storage element unit 50 is covered by the busbar cover 70. Furthermore, the busbar cover 70 is a component independent of the lid body 11 that is arranged to cover the entire energy storage element unit 50. Therefore, it is easy to form the busbar cover 70 in an efficient size and shape that matches the layout of the busbars 60.

[0041] The busbar cover 70 has a first fixed portion 71 fixed to the energy storage element unit 50 between both ends in the X-axis direction, which is the longitudinal direction. The first fixed portion 71 is also located between both ends in the Y-axis direction, which is the short-side direction of the busbar cover 70. In the present embodiment, the busbar cover 70 covers a plurality of busbars 60 arranged in the X-axis direction and has one first fixed portion 71 located between two adjacent busbars 60. The first fixed portion 71 is a through-hole provided in the busbar cover 70. The energy storage element unit 50 has a first fixing portion 31, which is a portion for fixing the first fixed portion 71, at a position corresponding to the first fixed portion 71. In the present embodiment, a busbar holder 30 provided in the energy storage element unit 50 has a protrusion that functions as the first fixing portion 31. The first fixing portion 31 fixes the first fixed portion 71 when inserted into the first fixed portion 71.

[0042] The busbar cover 70 according to this embodiment further has a second fixed portion 72 at an end in the X-axis direction, and the busbar holder 30 of the energy storage element unit 50 is provided with a second fixing portion 32 that fixes the second fixed portion 72 at a position corresponding to the second fixed portion 72. The second fixed portion 72 is a through-hole formed in the busbar cover 70, similar to the first fixed portion 71, and the second fixing portion 32 is a protrusion, similar to the first fixed portion 31. In other words, the second fixing portion 32 fixes the second fixed portion 72 when inserted into the second fixed portion 72.

[0043] In the present embodiment, the first fixing portion 31 fixes the first fixed portion 71 by heat crimping the tip portion exposed from the first fixed portion 71, and the second fixing portion 32 similarly fixes the second fixed portion 72 by heat crimping the tip portion exposed from the second fixed portion 72. The method of fixing the first fixing portion 31 to the first fixed portion 71 is not limited to heat crimping. For example, the first fixing portion 31 may fix the first fixed portion 71 by press-fitting, bonding, fastening, or the like. This also applies to the second fixing portion 32 and the second fixed portion 72.

[0044] As described above, the energy storage device 1 according to this embodiment includes the energy storage elements 100, the energy storage element units 50 that are arranged on either side of the energy storage elements 100 in the first direction (positive Z-axis direction) and that include the bus bars 60 electrically connected to the energy storage elements 100, and the bus bar cover 70. When viewed from the first direction, the bus bar cover 70 is a series of members that cover the bus bars 60 and expose areas of the energy storage element units 50 where the bus bars 60 are not arranged. The bus bar cover 70 has first fixed portions 71 that are portions that are fixed to the energy storage element units 50. The first fixed portions 71 are provided at positions between both end portions of the bus bar cover 70 in a second direction (X-axis direction) that is perpendicular to the first direction and between both end portions of the bus bar cover 70 in a third direction (Y-axis direction) that is perpendicular to the first direction and the second direction.

[0045] With this configuration, for example, the bus bar cover 70 can be fixed at a position other than the end of the bus bar cover 70 in a plan view. Therefore, the bus bar cover 70 can be stably fixed by, for example, one first fixed portion 71. As a result, problems such as the bus bar cover 70 being displaced due to vibration or impact, for example, and as a result, the bus bar 60 becoming electrically conductive with other conductive members, are unlikely to occur.

[0046] Furthermore, the busbar cover 70 can be realized using a member of a size and shape that substantially covers only the arrangement area of the busbar 60. This allows for the miniaturization of the energy storage element unit 50 on which the busbar cover 70 is arranged, or the amount of material required to form the busbar cover 70 to be reduced. Furthermore, because the busbar cover 70 does not cover the entire energy storage element unit 50 in a plan view, it is relatively easy to visually recognize, for example, the connection points between the first fixed portions 71 and the energy storage element unit 50. This facilitates the arrangement of the busbar cover 70 on the energy storage element unit 50. Specifically, in this embodiment, it is easy to insert the first fixing portions 31, which are protrusions, into the first fixed portions 71, which are through holes. Furthermore, because there is an area on the top surface of the energy storage element unit 50 that is not covered by the busbar cover 70, this area can be used to arrange electrical devices 40, such as BMUs or relay units, and wiring (electrical components), while electrically insulating the busbars 60 from the electrical components. This allows the size of the energy storage device 1 in the height direction (Z-axis direction) to be smaller than, for example, when the electrical equipment 40 is arranged on top of the bus bar cover 70. Furthermore, because the bus bar cover 70 does not cover the electrical equipment 40 and the like arranged on the upper surface of the energy storage element unit 50, it is easy to arrange and maintain electrical components on the energy storage element unit 50 after the bus bar cover 70 is fixed.

[0047] Thus, the power storage device 1 according to this embodiment is a power storage device with a simple configuration and improved safety.

[0048] For example, the end of the busbar cover 70 in the X-axis direction may be within a distance of approximately 1 / 10 of the total length of the busbar cover 70 in the X-axis direction from the edge of the busbar cover 70 in the X-axis direction. For example, if the total length of the busbar cover 70 in the X-axis direction is 30 cm, the end of the busbar cover 70 in the X-axis direction may be defined as a range of approximately 3 cm from the edge of the busbar cover 70 in the X-axis direction. Furthermore, for example, the portion between both end portions of the busbar cover 70 in the X-axis direction may also be referred to as the "middle portion." In this case, in this embodiment, the busbar cover 70 can be described as having the first fixed portion 71 in the middle portion in the X-axis direction and also in the middle portion in the Y-axis direction.

[0049] Furthermore, in a plan view, the area (coverage area) of the bus bar cover 70 covering the energy storage element unit 50 may be smaller than the entire energy storage element unit 50. For example, the bus bar cover 70A may include the arrangement area of the two bus bars 60 that the bus bar cover 70A is to cover, and may cover an area smaller than half of the energy storage element unit 50 in the Y-axis direction. More preferably, the bus bar cover 70A may include the arrangement area of the two bus bars 60, and may cover an area smaller than one-third of the energy storage element unit 50 in the Y-axis direction.

[0050] In the present embodiment, energy storage element unit 50 has bus bar holder 30 that holds bus bar 60, and bus bar holder 30 has first fixing portions 31 that fix first fixed portions 71.

[0051] That is, in this embodiment, the first fixing portion 31 and the first fixed portion 71 are combined and formed on the busbar holder 30 and the busbar cover 70, which are made of an electrically insulating resin, allowing for a high degree of freedom in the size and shape of the first fixing portion 31 and the first fixed portion 71. Therefore, for example, it is easy to form the first fixing portion 31 and the first fixed portion 71 that are easy to fix or that can obtain a large fixing force. That is, the busbar cover 70 can be fixed more reliably to the busbar holder 30.

[0052] In the present embodiment, bus bar cover 70 further includes second fixed portions 72, which are portions fixed to energy storage element units 50, at ends of bus bar cover 70 in the X-axis direction, which is the longitudinal direction of bus bar cover 70.

[0053] In other words, the busbar cover 70, which is elongated in the second direction, is fixed to the first fixing portion 31 at its longitudinal intermediate portion and also at its longitudinal end portions. By fixing the busbar cover 70 with multiple fixing portions, displacement or deformation due to vibration or impact is suppressed, thereby further improving the safety of the energy storage device 1. In this embodiment, a second fixing portion 72 is provided at each end of the busbar cover 70 in the X-axis direction, which is the longitudinal direction. Two second fixing portions 32 are provided on the busbar holder 30 of the energy storage element unit 50 to fix these two second fixing portions 72. This fixes both longitudinal end portions of the busbar cover 70, thereby more reliably suppressing displacement or deformation of the busbar cover 70. It should be noted that it is not essential that the second fixing portions 72 be provided at both longitudinal end portions of the busbar cover 70. For example, if the first fixed portion 71 is located relatively close to one of both longitudinal end portions of the busbar cover 70, the second fixed portion 72 may be provided only on the other of the both longitudinal end portions. In other words, the busbar cover 70 may have the second fixed portion 72 on at least one of both longitudinal end portions of the busbar cover 70 in the X-axis direction.

[0054] In addition, in this embodiment, the energy storage element unit 50 further includes a spacer 130 that is arranged in an orientation facing the energy storage element 100 in the X-axis direction and that is aligned with the first fixed portion 71 in the Z-axis direction.

[0055] 4, the central spacer 130 of the three spacers 130 is located directly below the first fixed portion 71 of the bus bar cover 70A. The spacers 130 at both ends in the X-axis direction of the three spacers 130 are also located directly below the two first fixed portions 71 of the bus bar cover 70B.

[0056] According to this configuration, the first fixed portion 71 is provided, for example, by utilizing a space above the spacer 130 that is equivalent to the thickness of the spacer 130. This makes it easy to ensure a working space for fixation by, for example, heat crimping, fastening, press-fitting, or the like, and also makes it easy to obtain sufficient fixation force. Furthermore, if the size of the first fixed portion 71 in the X-axis direction is made relatively large to ensure sufficient fixation force, etc., a thicker spacer 130 can be disposed by utilizing the space below the first fixed portion 71. This improves the impact resistance of the energy storage device 1 or improves the thermal insulation performance between the energy storage elements 100, and as a result, the safety of the energy storage device 1 is further improved.

[0057] Note that a spacer 135 may be arranged at a position aligned with the second fixed portion 72 of the busbar cover 70 in the Z-axis direction. Furthermore, if the energy storage device 1 includes a restraining member that restrains the energy storage element array 101 in the X-axis direction, an end plate (not shown) of the restraining member may be arranged at a position aligned with the second fixed portion 72 in the Z-axis direction. That is, a spacer, an end plate, or the like may be arranged in the space below the second fixed portion 72. Furthermore, the second fixed portion 72, which can obtain sufficient fixing force, may be provided in the space above the spacer, end plate, or the like. In other words, since the energy storage element 100 is not arranged in a position aligned with the first fixed portion 71 or the second fixed portion 72 in the Z-axis direction, the space below the first fixed portion 71 or the second fixed portion 72 can be used as space for arranging the spacer, or the like. Furthermore, the first fixed portion 71 or the second fixed portion 72, which can obtain sufficient fixing force, may be provided in the space above the space for arranging the spacer, or the like, located to the side of the energy storage element 100.

[0058] In this embodiment, a plurality of bus bars 60 are arranged side by side in the X-axis direction, and the first fixed portions 71 are arranged between two adjacent bus bars 60 when viewed from the positive direction of the Z-axis. Specifically, in bus bar cover 70A, the first fixed portions 71 are arranged between the two bus bars 60 covered by bus bar cover 70A. In bus bar cover 70B, the first fixed portions 71 are arranged between each pair of adjacent bus bars 60 among the three bus bars 60 covered by bus bar cover 70B.

[0059] According to this configuration, the first fixed portion 71, which is a part of the busbar cover 70 made of an insulating material, is positioned between two adjacent busbars 60, and therefore the first fixed portion 71 can function as a portion that prevents direct conduction between these busbars 60. Furthermore, if the two busbars 60 are spaced a relatively long distance apart from a safety standpoint, it is possible to use that long distance to form the first fixed portion 71 with a relatively large width in the X-axis direction. This improves the fixing force of the busbar cover 70 by the first fixed portion 71, or simplifies the task of fixing the first fixed portion 71 to the first fixing portion 31.

[0060] [3. Modifications] Although the energy storage device 1 according to the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. In other words, the embodiment disclosed herein is illustrative in all respects and is not restrictive, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0061] For example, the fixing portion of the energy storage element unit 50 for fixing the bus bar cover 70 may be arranged somewhere other than the bus bar holder 30. For example, a protrusion may be provided on the upper end surface of the spacer 130, and the protrusion may be used as a fixing portion for fixing the first fixed portion 71 of the bus bar cover 70. In this case, the energy storage element unit 50 does not need to have the bus bar holder 30. Furthermore, the bus bar cover 70 may be fixed using a protrusion or a hole provided on the energy storage element 100 or the bus bar 60, for example. In other words, the fixing portion for fixing the bus bar cover 70 may be arranged on the energy storage element 100 or the bus bar 60 of the energy storage element unit 50.

[0062] Furthermore, the energy storage element unit 50 may not have the spacers 130 and 135. For example, when an insulating film made of an insulating material is arranged along the outer surface of each of the containers 110 of the multiple energy storage elements 100, the energy storage element unit 50 may not have the spacers 130 and 135.

[0063] Furthermore, it is sufficient that at least the outer surface of the bus bar cover 70 is made of an insulating material. That is, the bus bar cover 70 may be made of, for example, a metal base material and an insulating material (such as resin, rubber, or glass) covering the surface of the base material. This improves, for example, the impact resistance of the bus bar cover 70.

[0064] Furthermore, the number and layout of the first fixed portions 71 and second fixed portions 72 of the busbar cover 70 are not limited to the numbers and layouts shown in Figures 4 to 6. For example, if the busbar cover 70 is relatively small, only one first fixed portion 71 may be provided at a position between both end portions in the X-axis direction and between both end portions in the Y-axis direction.

[0065] Furthermore, configurations constructed by arbitrarily combining the components included in the above-described embodiments and their modifications are also included within the scope of the present invention. [Industrial Applicability]

[0066] The present invention can be applied to an electricity storage device including an electricity storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0067] 1. Energy storage device 30 Busbar holder 31 First fixed part 32 Second fixed part 50 Energy storage element unit 60, 65 busbars 70, 70A, 70B busbar cover 71 First fixed part 72 Second fixed part 100 Energy storage element 130, 135 spacer

Claims

1. an energy storage element unit including an energy storage element and a bus bar disposed on a side of the energy storage element in a first direction and electrically connected to the energy storage element; a bus bar cover that is a series of members that covers the bus bar and exposes an area of the energy storage element unit where the bus bar is not arranged, when viewed from the first direction, the bus bar cover has a first fixed portion that is a portion that is fixed to the energy storage element unit, the first fixed portion is provided at a position between both end portions of the bus bar cover in a second direction perpendicular to the first direction and between both end portions of the bus bar cover in a third direction perpendicular to the first direction and the second direction, The bus bars are arranged in a plurality of rows in the second direction, the first fixed portion is disposed between two adjacent bus bars when viewed from the first direction; Energy storage device.

2. A storage element unit including a storage element and a bus bar arranged on a side of the storage element in a first direction and electrically connected to the storage element; a bus bar cover that is a series of members that covers the bus bar and exposes an area of the energy storage element unit where the bus bar is not arranged, when viewed from the first direction, the bus bar cover has a first fixed portion that is a portion that is fixed to the energy storage element unit, the first fixed portion is provided at a position between both end portions of the bus bar cover in a second direction perpendicular to the first direction and between both end portions of the bus bar cover in a third direction perpendicular to the first direction and the second direction, the energy storage element unit has a bus bar holder that holds the bus bar, the bus bar holder has a fixing portion that fixes the first fixed portion; Energy storage device.

3. the bus bar cover further includes a second fixed portion, which is a portion fixed to the energy storage element unit, at at least one end of both ends of the bus bar cover in the second direction, which is the longitudinal direction of the bus bar cover; The electricity storage device according to claim 1 or 2.

4. the energy storage element unit further includes a spacer disposed in a position facing the energy storage element in the second direction and aligned with the first fixed portion in the first direction. The electricity storage device according to any one of claims 1 to 3.

5. The energy storage element unit includes a plurality of the energy storage elements arranged in the second direction and electrically connected to each other, the spacer is an intermediate spacer disposed between two of the energy storage elements adjacent to each other in the second direction, the plurality of energy storage elements include a parallel energy storage element group, which is two of the energy storage elements adjacent to each other in the second direction and connected in parallel, and a series energy storage element group, which is two of the energy storage elements adjacent to each other in the second direction and connected in series, the intermediate spacer is disposed only in the series storage element group among the parallel storage element group and the series storage element group, a fixing portion for fixing the first fixed portion is provided at an end portion of the intermediate spacer in the first direction; The electricity storage device according to claim 4.

6. an energy storage element unit including an energy storage element and a bus bar disposed on a side of the energy storage element in a first direction and electrically connected to the energy storage element; a bus bar cover that is a series of members that covers the bus bar and exposes an area of the energy storage element unit where the bus bar is not arranged, when viewed from the first direction, the bus bar cover has a first fixed portion that is a portion that is fixed to the energy storage element unit, the first fixed portion is provided at a position between both end portions of the bus bar cover in a second direction perpendicular to the first direction and between both end portions of the bus bar cover in a third direction perpendicular to the first direction and the second direction, the energy storage element unit is provided with a fixing portion that fixes the first fixed portion, a portion of the fixing portion is exposed in the first direction from the first fixed portion; Energy storage device.

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