Energy storage device

Abstract

To provide a power storage device which has improved reliability with a simple configuration.SOLUTION: A power storage device 1 comprises a power storage element unit 20 and an outer package 10. The outer package 10 has: an opening 12a into which the power storage element unit 20 can be inserted; a bottom wall part 19; a first lateral wall part 13; a second lateral wall part 14; and a coupling member 11a which couples the first lateral wall part 13 to the second lateral wall part 14. The first lateral wall part 13 is located at a position facing the power storage element unit 20. The second lateral wall part 14 is provided opposite to the first lateral wall part 13 across the power storage element unit 20. The coupling member 11a is bonded to the first lateral wall part 13 at a first bonding part 40A, and it is bonded to the second lateral wall part 14 at a second bonding part 40B. The first bonding part 40A and the second bonding part 40B are disposed so as to be spaced apart from each other. The first bonding part 40A, the second bonding part 40B, and a central part 20a of the power storage element unit 20 are disposed at positions aligned in an X-axis direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a power storage device including a plurality of power storage elements.

Background Art

[0002] Patent Document 1 discloses a battery pack including a pair of end plates and a plurality of battery cells arranged in a row and disposed between the pair of end plates. This battery pack further includes a top plate member disposed on top of the plurality of battery cells, a bottom plate member disposed under the plurality of battery cells, and a side plate member disposed on the sides of the plurality of battery cells. The pair of end plates are each connected to the top plate member, the bottom plate member, and the side plate member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional battery pack (power storage device), a structure is adopted in which a power storage element unit composed of a plurality of battery cells (power storage elements) arranged in a row is sandwiched by end plates disposed on both sides in the arrangement direction. Thereby, it is possible to suppress the swelling of each of the plurality of power storage elements in the arrangement direction. Suppression of the swelling of the power storage elements is important from the viewpoint of suppressing damage to the power storage elements. However, when adopting a structure in which the power storage element unit is constrained by a pair of end plates as in the above conventional power storage device, it is necessary to arrange a constraining member including the pair of end plates inside the exterior body that houses the power storage element unit. This becomes a factor in the complication or enlargement of the configuration of the power storage device.

[0005] This invention was made by the present inventors by newly focusing on the above-mentioned problems, and aims to provide an energy storage device equipped with multiple energy storage elements that has a simple configuration and improved reliability. [Means for solving the problem]

[0006] A power storage device according to one aspect of the present invention comprises a power storage element unit having a plurality of power storage elements arranged in a line in a first direction, and an outer casing for housing the power storage element unit, the outer casing having an opening at its end in a second direction perpendicular to the first direction into which the power storage element unit can be inserted, wherein the outer casing has a bottom wall portion provided at a position facing the opening in the second direction, a first side wall portion connected to the bottom wall portion and located at a position facing the power storage element unit in the first direction, and a portion provided on the opposite side of the first side wall portion with the power storage element unit in between. The unit comprises a second side wall portion and a connecting member connecting the first side wall portion and the second side wall portion, wherein the connecting member is joined at a first joint portion provided at the first end portion which is the end portion of the first side wall portion in the second direction, and at a second joint portion provided at the second end portion which is the end portion of the second side wall portion in the second direction, and the first joint portion and the second joint portion are arranged separately from each other, and the first joint portion, the second joint portion, and the central portion of the energy storage element unit in a third direction perpendicular to the first and second directions are arranged in a position aligned in the first direction. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage device with improved reliability and a simple configuration. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing the external appearance of the energy storage device according to the embodiment. [Figure 2] This is an exploded perspective view of the energy storage device according to the embodiment. [Figure 3] This is an exploded perspective view of the energy storage element unit according to the embodiment. [Figure 4] This is a perspective view showing the exterior body and energy storage element unit according to the embodiment. [Figure 5] This is a plan view showing the exterior body and energy storage element unit according to the embodiment. [Figure 6] This is a partially cutaway perspective cross-sectional view showing the structural relationship between the exterior body and the energy storage element unit according to the embodiment. [Modes for carrying out the invention]

[0009] A power storage device according to one aspect of the present invention comprises a power storage element unit having a plurality of power storage elements arranged in a line in a first direction, and an outer casing for housing the power storage element unit, the outer casing having an opening at its end in a second direction perpendicular to the first direction into which the power storage element unit can be inserted, wherein the outer casing has a bottom wall portion provided at a position facing the opening in the second direction, a first side wall portion connected to the bottom wall portion and located at a position facing the power storage element unit in the first direction, and a portion provided on the opposite side of the first side wall portion with the power storage element unit in between. The unit comprises a second side wall portion and a connecting member connecting the first side wall portion and the second side wall portion, wherein the connecting member is joined at a first joint portion provided at the first end portion which is the end portion of the first side wall portion in the second direction, and at a second joint portion provided at the second end portion which is the end portion of the second side wall portion in the second direction, and the first joint portion and the second joint portion are arranged separately from each other, and the first joint portion, the second joint portion, and the central portion of the energy storage element unit in a third direction perpendicular to the first and second directions are arranged in a position aligned in the first direction.

[0010] Each of the multiple energy storage elements contained in the energy storage element unit is most prone to bulging at its center in the third direction. In contrast, in the energy storage device according to this embodiment, the portions of the first side wall and the second side wall of the outer casing, which are positioned to sandwich the energy storage element unit in the first direction, that face the center are connected by a connecting member. This suppresses displacement or deformation of the portions of the first side wall and the second side wall that face the center, in the direction away from each other. Therefore, the first side wall and the second side wall effectively act to suppress the expansion of each of the multiple energy storage elements in the energy storage element unit. As a result, for example, damage caused by fatigue due to repeated expansion and contraction of the energy storage element container is less likely to occur. Thus, in the energy storage device according to this embodiment, there is no need to place restraining members or the like inside the outer casing to restrain the energy storage element unit, and the outer casing functions as a member that efficiently or effectively restrains the energy storage element unit. Therefore, the energy storage device according to this embodiment is an energy storage device with improved reliability in a simple configuration.

[0011] The connecting member is a lid that closes the opening, and the lid is joined to the opening periphery at a plurality of joints that are dispersed in the direction in which the opening periphery extends, and the first joint and the second joint are two of the plurality of joints.

[0012] In this configuration, a connecting member is realized by a cover that closes the opening of the outer casing. Furthermore, a first joint and a second joint are realized by a member for fixing the cover to the opening or by the joined parts of each other. In other words, a configuration for suppressing damage to the energy storage element is realized by utilizing the basic configuration of the energy storage device.

[0013] The exterior body may have ribs that protrude from the outer or inner surface of the first side wall at positions aligned with the central portion in the first direction.

[0014] According to this configuration, the deformation of the portion of the first side wall portion facing the central portion of the power storage element unit in the third direction is suppressed by the rib provided on the first side wall portion. Therefore, the expansion of the power storage element can be more reliably suppressed.

[0015] The end portion of the power storage element unit facing the first side wall portion in the first direction may be arranged in a state of contacting the first side wall portion.

[0016] According to this configuration, since the end portion of the power storage element unit in the first direction is arranged in a state of contacting the first side wall portion, the expansion of the power storage element unit in the first direction is more reliably suppressed. As a result, damage and the like caused by fatigue due to repeated expansion and contraction of each power storage element are more reliably suppressed.

[0017] The first joint portion may include a bolt for fixing the connecting member to the first side wall portion.

[0018] According to this configuration, the connecting member and the first side wall portion can be firmly connected using bolts, and as a result, the expansion at the central portion of the power storage element unit in the third direction can be more reliably suppressed.

[0019] Hereinafter, a power storage device according to an embodiment (including its modification) of the present invention will be described with reference to the drawings. Each of the embodiments described below shows comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. In each figure, dimensions and the like are not strictly illustrated. Further, in each figure, the same or similar components are denoted by the same reference numerals.

[0020] In the following description and drawings, the direction in which the short sides of the power storage element face each other, or the longitudinal direction of the cover plate of the container of the power storage element, is defined as the Y-axis direction. The direction in which a plurality of power storage elements are arranged, or the direction in which the long sides of the power storage element face each other, is defined as the X-axis direction. The direction in which the main body (outer body main body) of the exterior of the power storage device and the lid body are arranged, or the vertical direction, is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that intersect (orthogonal in this embodiment) with each other. Depending on the usage mode, there may be cases where the Z-axis direction is not the vertical direction, but hereinafter, for the sake of convenience of explanation, the Z-axis direction will be described as the vertical direction.

[0021] In the following description, for example, the X-axis plus direction indicates the arrow direction of the X-axis, and the X-axis minus direction indicates the direction opposite to the X-axis plus direction. The same applies to the Y-axis direction and the Z-axis direction. When simply referring to the "X-axis direction", it means the two-way direction parallel to the X-axis or either one of the directions. The same applies to the terms related to the Y-axis and Z-axis.

[0022] Furthermore, expressions indicating relative directions or postures such as parallel and orthogonal also include cases where they are not strictly in that direction or posture, in principle. For example, when it is said that two directions are orthogonal, it not only means that the two directions are completely orthogonal, but also means that they are substantially orthogonal, that is, for example, including a difference of about a few percent. In the following description, when expressing "insulation", it means "electrical insulation".

[0023] (Embodiment) [1. General description of the power storage device] First, the schematic configuration of the power storage device 1 according to the embodiment will be described. FIG. 1 is a perspective view showing the appearance of the power storage device 1 according to the embodiment. FIG. 2 is an exploded perspective view of the power storage device 1 according to the embodiment. FIG. 3 is an exploded perspective view of the power storage element unit 20 according to the embodiment. Inside the exterior 10, in addition to the members shown in the figures after FIG. 2, other members such as sensors for temperature and voltage measurement and electric wires connected to the sensors are also housed, but the illustration and description of these members are omitted.

[0024] The energy storage device 1 is a device that can charge electricity from an external source and discharge electricity to an external source. The energy storage device 1 is, for example, a battery module (battery pack) used for power storage or power supply purposes. Specifically, the energy storage device 1 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage device 1 can also be used as a stationary battery for household or commercial use.

[0025] As shown in Figures 1 and 2, the energy storage device 1 comprises an outer casing 10 and an energy storage element unit 20 housed within the outer casing 10. Above the energy storage element unit 20 is a busbar holder 30 that holds a busbar 60 connected to the energy storage element 100.

[0026] The outer casing 10 is a box-shaped container (module case) that constitutes the housing of the energy storage device 1. In other words, the outer casing 10 is positioned outside the energy storage element unit 20 and the busbar holder 30, fixing them in place and protecting them from impacts, etc. In this embodiment, the outer casing 10 is made of a metal such as iron, aluminum, or an aluminum alloy. In addition to metal, resins can also be used as the material for forming the outer casing 10. Examples of such resins include polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), or ABS resin.

[0027] The outer casing 10 has an opening 12a at its end in the positive Z-axis direction into which the energy storage element unit 20 can be inserted, and a bottom wall portion 19 located opposite the opening 12a. Specifically, the outer casing 10 comprises an outer casing body 12 and a lid 11, with the opening 12a and the bottom wall portion 19 located in the outer casing body 12. The outer casing body 12 is a bottomed rectangular cylindrical housing with the opening 12a formed therein, and it houses the energy storage element unit 20. The outer casing body 12 has four side walls, including a side wall portion 15 that separates the inside and outside of the outer casing 10. The energy storage element unit 20 is surrounded by the four side walls of the outer casing body 12 inside the outer casing 10. Of these four side walls, the first side wall portion 13 and the second side wall portion 14 are located opposite the energy storage element unit 20 in the X-axis direction. As shown in Figure 2, multiple ribs 50 are arranged on the outer surface of the first side wall portion 13. Although not shown in Figure 2, multiple ribs 50 are similarly arranged on the outer surface of the second side wall portion 14. The outer casing 10 may also include elements not shown in Figures 1 and 2, such as an exhaust pipe for discharging gas from inside the outer casing 10 to the outside.

[0028] The cover 11 is a rectangular member that closes the opening 12a of the exterior body 12. The cover 11 is joined to the exterior body 12 by a plurality of joints 40, thereby fixing the cover 11 to the exterior body 12. In this embodiment, each of the plurality of joints 40 includes a bolt 41 and a fixing hole portion 42 in which a screw hole into which the bolt 41 is screwed is formed. Specifically, a through hole 43 is provided in the peripheral edge of the cover 11 through which the bolt 41 passes, and a fixing hole portion 42 is provided in the opening peripheral edge portion 12b, which is the peripheral edge of the opening 12a of the exterior body 12. The bolt 41 is screwed into the fixing hole portion 42 of the exterior body 12 while passing through the through hole 43 of the cover 11. This forms a joint 40 that joins the cover 11 and the exterior body 12. In this embodiment, a plurality of such joints 40 are provided dispersed in the direction in which the opening peripheral edge portion 12b extends. This ensures that the lid 11 and the outer casing body 12 are joined together stably and in a balanced manner.

[0029] Furthermore, in this embodiment, the lid 11 also functions as a connecting member 11a that connects the first side wall portion 13 and the second side wall portion 14 in the X-axis direction within the outer casing 10. This allows the first side wall portion 13 and the second side wall portion 14 to act effectively as members that suppress the expansion of the energy storage element unit 20. The manner in which the outer casing 10 suppresses the expansion of the energy storage element unit 20 will be described later with reference to Figures 4 to 6.

[0030] The energy storage element unit 20 has a plurality of energy storage elements 100 and a cell holder 130 that holds each of the plurality of energy storage elements 100. The energy storage element 100 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. As shown in Figure 3, the energy storage element 100 has a flat rectangular parallelepiped (square) container 110 and a pair of electrode terminals 120 (positive electrode and negative electrode) fixed to the container 110. Inside the container 110 are an electrode body, current collector, electrolyte, etc. (not shown). An example of an electrode body of the energy storage element 100 is a wound-type electrode body formed by winding together layers arranged with a separator sandwiched between a positive electrode plate and a negative electrode plate. In addition, the energy storage element 100 may be equipped with a stacked electrode body formed by stacking multiple flat electrode plates, or a bellows-type electrode body formed by folding electrode plates in a bellows-like manner.

[0031] 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 a capacitor. The energy storage element 100 may not be a secondary battery, but a primary battery that allows the user to use the stored electricity without charging. The energy storage element 100 may be a battery using 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 prismatic shape, but may be a polygonal prism, cylindrical shape, elliptical prism shape, oblong cylindrical shape, etc.

[0032] In this embodiment, as shown in Figure 3, the container 110 has a container body 111 and a lid plate 112 that closes the opening of the container body 111. The container 110 is structured so that after the electrode body or the like is placed inside the container body 111, the container body 111 and the lid plate 112 are joined by welding or the like to seal the inside. The material of the container 110 (container body 111 and lid plate 112) is not particularly limited and can be made of weldable (joinable) metals such as stainless steel, aluminum, aluminum alloy, iron, plated steel sheet, etc., but resin can also be used.

[0033] The container body 111 has a pair of long sides 110a and a pair of short sides 110b. Positive and negative electrode terminals 120 and a gas discharge valve 105 are arranged on the lid plate 112. The gas discharge valve 105 is a part that opens (opens) when the internal pressure of the container 110 rises excessively, thereby discharging the gas inside the container 110 to the outside. In the energy storage element unit 20, each of the multiple energy storage elements 100 is arranged in a position where the two electrode terminals 120 and the gas discharge valve 105 are oriented in the Z-axis positive direction, and the long sides 110a are oriented in the alignment direction (X-axis direction). In this embodiment, the X-axis direction is an example of a first direction, and the Z-axis positive direction is an example of a second direction perpendicular to the first direction.

[0034] The energy storage element unit 20 has 12 energy storage elements 100 configured as described above. In this embodiment, each of the 12 energy storage elements 100 is positioned between two cell holders 130. In other words, the energy storage element unit 20 according to this embodiment has 13 cell holders 130. Of these cell holders 130, a pair of cell holders 130 located at both ends in the X-axis direction are referred to as cell holder 131 to distinguish them from the others. Of these cell holders 130, a cell holder 130 located between two adjacent energy storage elements 100 is referred to as cell holder 132 to distinguish it from the others.

[0035] The cell holder 130 has the function of stabilizing the position of the energy storage element 100 by holding it, as well as the function of insulating the container 110 of the energy storage element 100 from other conductive members adjacent to the energy storage element 100 (including the containers 110 of other energy storage elements 100). Specifically, the cell holder 130 according to this embodiment has portions facing the long side 110a, a pair of short sides 110b, and the bottom surface of one energy storage element 100. Therefore, the cell holder 130 can electrically insulate the energy storage element 100 from other energy storage elements 100 or metal casings 10 located in the direction of the long side 110a, the Y-axis direction, and the Z-axis negative direction. The cell holder 130 is formed from one of the electrically insulating resin materials that can be used as the material for the casing 10.

[0036] The busbar holder 30 is a flat, rectangular insulating member positioned opposite the cover plate 112 of the energy storage element 100 and holding a plurality of busbars 60. The busbar holder 30 is formed of, for example, one of the electrically insulating resin materials that can be used as the material for the exterior body 10. The busbars 60 positioned on the busbar holder 30 are positioned relative to the electrode terminals 120 to be joined, and in that state are joined to the electrode terminals 120, for example, by laser welding. In this embodiment, in the 12 energy storage elements 100 of the energy storage element unit 20, three consecutively arranged energy storage elements 100 are connected in parallel by busbars 60. This forms four sets of parallel-connected energy storage elements 100. Furthermore, the four sets of energy storage elements 100 are connected in series by three busbars 60.

[0037] In other words, the electrode terminals 120 of the two end sets of energy storage elements 100 in the four sets of energy storage elements 100 connected in series are the positive terminal (total positive terminal) and negative terminal (total negative terminal) of the energy storage element unit 20. In this embodiment, the positive electrode terminals 120 of one set (3 elements) of energy storage elements 100 at the X-axis negative end of the 12 energy storage elements 100 are the positive terminal (total positive terminal) of the energy storage element unit 20. The negative electrode terminals 120 of one set (3 elements) of energy storage elements 100 at the X-axis positive end of the 12 energy storage elements 100 are the negative terminal (total negative terminal) of the energy storage element unit 20.

[0038] Although not shown in the diagram, the side wall portion 15 of the outer casing 10 is provided with openings through which the ends of the busbars 60, which are connected to the positive and negative electrodes of the energy storage element unit 20, pass. The ends of these two busbars 60 are exposed to the outside of the outer casing 10 through the openings provided in the side wall portion 15 (see Figure 1), and function as the positive and negative external terminals of the energy storage device 1.

[0039] Inside the outer casing 10, a control device and electrical equipment such as relays for controlling the charging state of the multiple energy storage elements 100 of the energy storage element unit 20 may be arranged. In this case, the energy storage device 1 may include, for example, a positive external terminal and a negative external terminal fixed to the lid 11, which are electrically connected to the energy storage element unit 20 via electrical equipment and a busbar 60.

[0040] The electrical connection configuration of the 12 energy storage elements 100 by the busbar 60 is not limited to the configuration described above. For example, all 12 energy storage elements 100 may be connected in series by multiple busbars 60. Furthermore, the number of energy storage elements 100 provided in the energy storage element unit 20 is not limited to 12. The number of energy storage elements 100 provided in the energy storage element unit 20 may be 2 or more.

[0041] In the energy storage device 1 configured in this way, the outer casing 10 has a configuration that can restrain the energy storage element unit 20 in the direction of the arrangement of the multiple energy storage elements 100. This suppresses the expansion of each of the multiple energy storage elements 100 in the energy storage element unit 20. The configuration for suppressing the expansion of the energy storage elements 100 by the outer casing 10 will be explained below with reference to Figures 4 to 6.

[0042] [2. Regarding the composition of the exterior] Figure 4 is a perspective view showing the exterior body 10 and the energy storage element unit 20 according to the embodiment. In Figure 4, the energy storage element unit 20 is housed in the exterior body 12, and the cover 11, which also functions as a connecting member 11a, is shown separated from the exterior body 12. Figure 5 is a plan view showing the exterior body 12 and the energy storage element unit 20 according to the embodiment. In Figure 5, the cover 11 (connecting member 11a) and the bolts 41 included in each of the multiple joints 40 are not shown. Figure 6 is a partially cutaway perspective cross-sectional view showing the structural relationship between the exterior body 10 and the energy storage element unit 20 according to the embodiment. In Figure 6, a perspective view is shown of the exterior body 10, in which the energy storage element unit 20 is housed, cut along the XZ plane passing through the first joint 40A and the second joint 40B. In Figures 4 to 6, other members such as the busbar holder 30 housed in the exterior body 10 are not shown.

[0043] As shown in Figures 4 to 6, in this embodiment, the lid 11 and the main body 12 of the outer casing 10 are joined at a plurality of joints 40. The outer casing 10 has a first side wall portion 13 and a second side wall portion 14 at positions facing the energy storage element unit 20 in the direction of arrangement of the plurality of energy storage elements 100 (X-axis direction). As shown in Figure 5, the first side wall portion 13 has a first joint portion 40A, which is one of the plurality of joints 40, positioned in the X-axis direction with the central portion 20a of the energy storage element unit 20. As shown in Figure 5, the second side wall portion 14 has a second joint portion 40B, which is one of the plurality of joints 40, positioned in the X-axis direction with the central portion 20a of the energy storage element unit 20.

[0044] The central portion 20a of the energy storage element unit 20 is the central part of the energy storage element unit 20 in the Y-axis direction. The Y-axis direction is an example of a third direction that is orthogonal to the first and second directions. More specifically, the central portion 20a of the energy storage element unit 20 is the portion that includes the center line C (see Figure 5) passing through the center of the energy storage element unit 20 in the Y-axis direction. In other words, the central portion 20a of the energy storage element unit 20 includes the central portion in the Y-axis direction of each of the multiple energy storage elements 100 that the energy storage element unit 20 has. Since each of these multiple energy storage elements 100 has a flattened shape in the X-axis direction, it has the characteristic that when the internal pressure of the container 110 increases, the central portion in the Y-axis direction tends to expand in the X-axis direction. If the container 110 of the energy storage elements 100 repeatedly expands and contracts, damage due to metal fatigue may occur, for example, at the joint between the lid plate 112 and the container body 111. Therefore, suppressing the expansion of the container 110, and in particular the central portion of the short side 110b in the opposing direction (Y-axis direction in this embodiment), which is a part of the container 110 that is prone to expansion, is important from the viewpoint of improving the reliability of the energy storage device 1. Accordingly, in the energy storage device 1 according to this embodiment, the outer casing 10 has a structure for suppressing the expansion of the central portion 20a of the energy storage element unit 20 in the Y-axis direction. Specifically, as described above, the first side wall portion 13 and the second side wall portion 14 are connected by a connecting member 11a, which is the lid 11, at the portions facing the central portion 20a of the energy storage element unit 20. As a result, the expansion of the central portion 20a of the energy storage element unit 20 in the X-axis direction is suppressed, and as a result, the expansion of each energy storage element 100 is suppressed efficiently or effectively.

[0045] In other words, the energy storage device 1 according to this embodiment comprises an energy storage element unit 20 having a plurality of energy storage elements 100 arranged in line in the X-axis direction, and an outer casing 10 that houses the energy storage element unit 20. The outer casing 10 has an opening 12a at its end in the Z-axis positive direction, which is perpendicular to the X-axis direction, into which the energy storage element unit 20 can be inserted. The outer casing 10 has a bottom wall portion 19 located opposite the opening 12a in the Z-axis positive direction, a first side wall portion 13, a second side wall portion 14, and a connecting member 11a that connects the first side wall portion 13 and the second side wall portion 14. The first side wall portion 13 is connected to the bottom wall portion 19 and is located opposite the energy storage element unit 20 in the X-axis direction. The second side wall portion 14 is located on the opposite side of the first side wall portion 13, with the energy storage element unit 20 in between. The connecting member 11a is joined to the first side wall portion 13 at the first joint portion 40A and to the second side wall portion 14 at the second joint portion 40B. The first joint portion 40A is provided at the first end portion 13A (see Figure 6), which is the end portion of the first side wall portion 13 in the Z-axis positive direction. The second joint portion 40B is provided at the second end portion 14B (see Figure 6), which is the end portion of the second side wall portion 14 in the Z-axis positive direction. The first joint portion 40A and the second joint portion 40B are arranged separately from each other. The first joint portion 40A, the second joint portion 40B, and the central portion 20a of the energy storage element unit 20 in a third direction perpendicular to the X-axis direction and the Z-axis positive direction are arranged in a position aligned in the X-axis direction, as shown in Figures 5 and 6.

[0046] As described above, in the energy storage device 1 according to this embodiment, the portions of the first side wall portion 13 and the second side wall portion 14 of the outer casing 10, which are positioned to sandwich the energy storage element unit 20 in the X-axis direction, and which face the central portion 20a, are connected by a connecting member 11a. This suppresses displacement or deformation of the portions of the first side wall portion 13 and the second side wall portion 14 that face the central portion 20a, in a direction away from each other. Therefore, the first side wall portion 13 and the second side wall portion 14 effectively act to suppress the expansion of each of the multiple energy storage elements 100 of the energy storage element unit 20. As a result, for example, damage caused by fatigue due to repeated expansion and contraction of the container 110 of the energy storage element 100 is less likely to occur.

[0047] Furthermore, these effects are achieved by the outer casing 10 that houses the energy storage element unit 20. In other words, in the energy storage device 1, there is no need to place restraining members or the like inside the outer casing 10 to restrain the energy storage element unit 20, as the outer casing 10 functions as a member that efficiently or effectively restrains the energy storage element unit 20. Therefore, the energy storage device 1 according to this embodiment is an energy storage device with improved reliability in a simple configuration.

[0048] The central portion 20a of the energy storage element unit 20 described above is the portion that includes the center line C (see Figure 5). In this embodiment, a gas discharge valve 105 is located in the center of each energy storage element 100 in the Y-axis direction. Furthermore, these multiple gas discharge valves 105 are arranged in a line in the X-axis direction, that is, they are located at positions through which the center line C passes. Therefore, in this embodiment, the Y-axis range of the central portion 20a of the energy storage element unit 20 can be defined as the arrangement range of the gas discharge valves 105 in the Y-axis direction. For example, if the width of the gas discharge valve 105 in the Y-axis direction is L, the central portion 20a can be defined as the range of width L with the center line C as the center (a range of 0.5L each in the positive Y-axis direction and the negative Y-axis direction from the center line C). The Y-axis width L of the gas discharge valve 105 is, for example, about 20 mm, but is not limited to this. In other words, if the positions of the first joint 40A and the second joint 40B in the Y-axis direction are within the arrangement range of the gas discharge valve 105 in the Y-axis direction, then the first joint 40A, the second joint 40B, and the central part 20a of the energy storage element unit 20 are arranged in line in the X-axis direction. As a result, the outer casing 10 functions as a member that efficiently or effectively restrains the energy storage element unit 20. To obtain this effect, the range of the central part 20a of the energy storage element unit 20 in the Y-axis direction can also be defined using the width of the energy storage element 100 in the Y-axis direction. Specifically, by restraining a range of about 1 / 3 of the width in the Y-axis direction in the central part of the energy storage element 100 in the Y-axis direction, expansion in the X-axis direction is effectively or efficiently suppressed. Therefore, the range of the central part 20a in the Y-axis direction can be defined as the range including the center line C, and the range of 1 / 3 of the width in the Y-axis direction of the energy storage element 100 with the center line C as the center. For example, if the width of the energy storage element 100 in the Y-axis direction is 120 mm, the central part 20a can be defined as a range with a width of 40 mm centered on the center line C (a range of 20 mm each in the positive Y-axis direction and the negative Y-axis direction from the center line C).

[0049] Thus, the central portion 20a of the energy storage element unit 20 is a range with a predetermined width in the Y-axis direction. The first joint portion 40A and the second joint portion 40B each only need to be positioned within this range in the Y-axis direction, and the Y-axis position of these joint portions is not limited to one position. In other words, as long as the first joint portion 40A and the second joint portion 40B are located within the range of the central portion 20a in the Y-axis direction, one or both of the first joint portion 40A and the second joint portion 40B may be positioned offset from the center line C in the Y-axis direction. Even in this case, the first joint portion 40A, the second joint portion 40B, and the central portion 20a of the energy storage element unit 20 are said to be positioned in a aligned position in the X-axis direction.

[0050] Furthermore, the position of the first joint 40A, which serves as the criterion for determining whether the first joint 40A is aligned with the central part 20a of the energy storage element unit 20 in the X-axis direction, can be defined as the central position of the first joint 40A in the Y-axis direction. In other words, if the central position of the first joint 40A in the Y-axis direction is included within the range of the central part 20a, the first joint 40A is described as being aligned with the central part 20a of the energy storage element unit 20 in the X-axis direction. If the first joint 40A includes a bolt 41, the position of the first joint 40A can also be defined as being within the range of the width of the bolt 41's head in the Y-axis direction. In other words, if at least a portion of the range of the bolt 41's head in the Y-axis direction overlaps with the range of the central part 20a, the first joint 40A having the bolt 41 is described as being aligned with the central part 20a of the energy storage element unit 20 in the X-axis direction. These supplementary points regarding the position of the first joint 40A also apply to the position of the second joint 40B.

[0051] In this embodiment, the connecting member 11a that connects the first side wall portion 13 and the second side wall portion 14 is a cover 11 that closes the opening 12a. The cover 11 is joined to the opening peripheral portion 12b at a plurality of joint portions 40 that are dispersed in the direction in which the opening peripheral portion 12b extends, which is the peripheral edge of the opening 12a. The first joint portion 40A and the second joint portion 40B are two of the plurality of joint portions 40.

[0052] Thus, in this embodiment, the connecting member 11a is realized by the lid 11 that closes the opening 12a of the outer casing 10. Therefore, the first joint 40A and the second joint 40B are realized by a member for fixing the lid 11 to the opening 12a or by the joined parts of the two. In other words, a configuration for suppressing damage to the energy storage element 100 is realized by utilizing the basic configuration of the energy storage device 1. In this embodiment, it can also be explained that the lid 11 also serves as the connecting member 11a, or that the connecting member 11a also serves as the lid 11.

[0053] In this embodiment, as shown in Figures 4 and 6, the exterior body 10 has ribs 50A that protrude from the outer surface of the first side wall portion 13 at positions aligned with the central portion 20a in the X-axis direction.

[0054] More specifically, as shown in Figures 4 and 6, the outer surface of the first side wall 13 is provided with a plurality of ribs 50, and among these ribs 50, the rib 50 located in a position aligned with the central portion 20a in the X-axis direction is rib 50A. At least this rib 50A suppresses deformation of the portion of the first side wall 13 that faces the central portion 20a of the energy storage element unit 20. Therefore, the expansion of the energy storage element 100 can be suppressed more reliably. In this embodiment, the second side wall 14 is also provided with ribs 50. That is, the outer casing 10 has a rib 50B that protrudes from the outer surface of the second side wall 14 in a position aligned with the central portion 20a in the X-axis direction (see Figure 6). This suppresses deformation of the portion of the second side wall 14 that faces the central portion 20a of the energy storage element unit 20, and the expansion of the energy storage element 100 can be suppressed more reliably.

[0055] Each of the first side wall portion 13 and the second side wall portion 14 may have ribs 50 on its inner surface rather than its outer surface. In other words, even if each of the first side wall portion 13 and the second side wall portion 14 has ribs 50 on its inner surface, the deformation suppression effect can still be obtained. However, from the viewpoint of effectively utilizing the internal space of the outer casing 10, it is preferable that each of the first side wall portion 13 and the second side wall portion 14 has ribs 50 on its outer surface. Furthermore, from the viewpoint of reducing the possibility of damage to the energy storage element unit 20 by the ribs 50, it is also preferable that each of the first side wall portion 13 and the second side wall portion 14 has ribs 50 on its outer surface.

[0056] In this embodiment, as shown in Figures 5 and 6, the energy storage element unit 20 is positioned such that the end facing the first side wall 13 in the X-axis direction is in contact with the first side wall 13. Specifically, the energy storage element unit 20 has a cell holder 131 at a position facing the first side wall 13, and the energy storage element unit 20 is positioned such that the cell holder 131 is in contact with the first side wall 13.

[0057] With this configuration, the energy storage element unit 20 is positioned so that its X-axis end is in contact with the first side wall 13, thereby more reliably suppressing the expansion of the energy storage element unit 20 in the X-axis direction. This more reliably suppresses damage to each energy storage element 100 caused by fatigue due to repeated expansion and contraction. In this embodiment, the cell holder 131 facing the second side wall 14 of the energy storage element unit 20 is also in contact with the second side wall 14. In other words, even before use begins, the energy storage element unit 20 is sandwiched in the X-axis direction by the first side wall 13 and the second side wall 14. Therefore, displacement of the energy storage element unit 20 inside the outer casing 10 due to vibration or shock is suppressed, and expansion of the energy storage element unit 20 is also suppressed.

[0058] In this embodiment, the first joint portion 40A includes a bolt 41 for fixing the connecting member 11a (cover 11) to the first side wall portion 13.

[0059] With this configuration, the connecting member 11a and the first side wall portion 13 can be firmly connected using the bolt 41, and as a result, expansion in the central portion 20a of the energy storage element unit 20 can be more reliably suppressed.

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

[0061] For example, the joint 40 does not necessarily have to be the part where the connecting member 11a (cover 11) and the exterior body 12 are joined using a bolt 41. For example, the joint 40 may be formed by welding such as spot welding or by riveting. If the joint 40 includes a bolt 41, the screw hole into which the bolt 41 is inserted may be formed in a separate member from the exterior body 12. For example, a fixing hole 42 having a screw hole may be realized by a nut separate from the exterior body 12.

[0062] The connecting member 11a and the lid 11 may be separate components. For example, a connecting member separate from the lid 11 may be positioned below the lid 11, connecting the first side wall 13 and the second side wall 14. Even in this case, the configuration of the energy storage device 1 is simpler than, for example, the case in which a pair of end plates and a pair of connecting members connecting the pair of end plates are placed inside the outer casing 10 to restrain the energy storage element unit 20.

[0063] The energy storage element unit 20 does not necessarily have to have multiple cell holders 130. For example, instead of multiple cell holders 130, flat, insulating spacers may be arranged along the long sides 110a of each of the multiple energy storage elements 100. In this case, an insulating member may be placed between the energy storage element unit 20 and the bottom wall portion 19 of the outer casing 10. If an insulating member such as an insulating film is placed on the outer surface of each container 110 of the multiple energy storage elements 100, then cell holders and spacers or other members may not be placed between adjacent energy storage elements 100. In this case, insulating members may be placed at both ends of the energy storage element unit 20 in the X-axis direction to insulate the energy storage element unit 20 from the first side wall portion 13 and the second side wall portion 14.

[0064] The energy storage element unit 20 may include not only multiple energy storage elements 100 and multiple cell holders 130, but also multiple busbars 60 and busbar holders 30 (see Figure 2) connected to the electrode terminals 120 of the multiple energy storage elements 100. In other words, a configuration that adds busbar holders 30 and multiple busbars 60 to the energy storage element unit 20 according to the embodiment can also be called an "energy storage element unit".

[0065] The present invention also includes forms constructed by arbitrarily combining the components included in the above embodiments and their modified examples. [Industrial applicability]

[0066] This invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0067] 1. Energy storage device 10 Exterior 11 Lid 11a Connecting member 12. Main body of the exterior 12a opening 12b Periphery of the opening 13 First side wall part 13A First end 14 Second side wall part 14B Second end 19 Bottom wall section 20 Energy Storage Element Units 20a Central part 30 Busbar Holder 40 Joint 40A First joint 40B Second joint 41 volts 42 Fixing hole 43 Through hole 50, 50A, 50B Ribs 100 energy storage elements 110 Container

Claims

1. A storage element unit having multiple storage elements arranged in a line in the first direction, An outer casing for housing the energy storage element unit, comprising an outer casing having an opening at its end in a second direction perpendicular to the first direction into which the energy storage element unit can be inserted, The exterior body is, A bottom wall portion provided at a position opposite to the opening in the second direction, A first side wall portion connected to the bottom wall portion, located in the first direction opposite to the energy storage element unit, A second side wall portion is provided on the opposite side of the first side wall portion, with the energy storage element unit in between, It has a connecting member that connects the first side wall portion and the second side wall portion, The connecting member is joined at a first joint provided at the first end, which is the end of the first side wall in the second direction, and at a second joint provided at the second end, which is the end of the second side wall in the second direction, and the first joint and the second joint are arranged separately from each other. The first joint, the second joint, and the central portion of the energy storage element unit in a third direction perpendicular to the first and second directions are positioned in a line in the first direction. The exterior body has ribs that protrude from the outer surface of the first side wall at positions aligned in the central part in the first direction, At least a portion of the first joint is provided inside the rib, Energy storage device.

2. The connecting member is a cover that closes the opening. The cover is joined to the opening periphery at a plurality of joints that are dispersed in the direction in which the opening periphery extends, which is the periphery of the opening. The first joint and the second joint are two of the plurality of joints. The energy storage device according to claim 1.

3. The energy storage element unit is arranged such that the end facing the first side wall in the first direction is in contact with the first side wall. The energy storage device according to claim 1 or 2.

4. The first joint includes a bolt for fixing the connecting member to the first side wall. The energy storage device according to any one of claims 1 to 3.

5. The first joint portion includes a fixing hole portion into which the bolt is inserted, At least a portion of the aforementioned fixing hole is provided inside the rib. The energy storage device according to claim 4.

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