Energy storage device

Abstract

To provide a power storage device improved in reliability.SOLUTION: A power storage device 1 includes power storage elements 100 and a cell holder 130 supporting each of the power storage elements 100. The power storage elements 100 and the cell holders 130 are arranged side by side in an X-axis direction. Each cell holder 130 includes a holder body part 134 facing a long side face 110a that is a side face of the power storage element 100 in the X-axis direction, and a first side wall part 135A facing a short side face 110b that is a side face of the power storage element 100 in a Y-axis direction orthogonal to the X-axis direction. The first side wall part 135A is arranged along the short side face 110b from an end part of the holder body part 134 in the Y-axis direction. The first side wall part 135A is provided with a first projection 138A arranged in a position away from the holder body part 134 and in contact with the short side face 110b.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a power storage device including a power storage element.

Background Art

[0002] Patent Document 1 discloses a battery module having an array in which a plurality of batteries held by a cell holder are arranged. In this battery module, the cell holder includes a bottom wall portion and a top wall portion facing each other, a pair of side wall portions facing each other, and a back wall portion. The cell holder is configured such that the bottom wall portion, the top wall portion, and the side wall portion surround the back wall portion, and the batteries are held by these plurality of wall portions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The cell holder included in the conventional battery module has a pair of side wall portions at positions facing a pair of side surfaces of a case (container) of a rectangular battery (power storage element), and the battery is disposed between these pair of side wall portions. In this structure, in order to stabilize the position of the power storage element, it is preferable to bring each of the pair of side wall portions into contact with the side surface of the case of the power storage element located at a position facing the side wall portion. Stabilizing the position of the power storage element leads to, for example, suppression of occurrence of defects at the joint between the power storage element and the bus bar, which contributes to improvement of the reliability of the power storage device. However, there are tolerances in the sizes of the case of the power storage element and the cell holder, respectively. Therefore, when one cell holder selected from a plurality of cell holders is attached to each of a plurality of power storage elements, depending on the combination of the power storage element and the cell holder, there is a possibility that the cell holder cannot stably support the power storage element.

[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 with improved reliability. [Means for solving the problem]

[0006] An energy storage device according to one aspect of the present invention comprises an energy storage element and a holder for holding the energy storage element, wherein the energy storage element and the holder are arranged side by side in a first direction, and the holder has a main body portion facing a first side surface which is the side surface of the energy storage element in the first direction, and a first side wall portion facing a second side surface which is the side surface of the energy storage element in a second direction perpendicular to the first direction, the first side wall portion being arranged along the second side surface from the end of the main body portion in the second direction, and the first side wall portion is provided with a first projection that is positioned spaced apart from the main body portion and in contact with the second side surface. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage device with improved reliability. [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 first perspective view showing the appearance of the cell holder and the two energy storage elements according to the embodiment. [Figure 5] This is a second perspective view showing the appearance of the cell holder and the two energy storage elements according to the embodiment. [Figure 6] This is a perspective cross-sectional view showing the configuration of the end portion including the first side wall of the cell holder according to the embodiment. [Figure 7]This is a perspective cross-sectional view showing the configuration of the end portion including the third side wall of the cell holder according to the embodiment. [Figure 8] This is a plan view showing the cell holder according to the embodiment holding two energy storage elements. [Figure 9] This is a perspective view showing the appearance of the cell holder according to the embodiment. [Modes for carrying out the invention]

[0009] An energy storage device according to one aspect of the present invention comprises an energy storage element and a holder for holding the energy storage element, wherein the energy storage element and the holder are arranged side by side in a first direction, and the holder has a main body portion facing a first side surface which is the side surface of the energy storage element in the first direction, and a first side wall portion facing a second side surface which is the side surface of the energy storage element in a second direction perpendicular to the first direction, the first side wall portion being arranged along the second side surface from the end of the main body portion in the second direction, and the first side wall portion is provided with a first projection that is positioned spaced apart from the main body portion and in contact with the second side surface.

[0010] In this configuration, the first projection provided on the first side wall of the holder is positioned opposite the second side surface of the energy storage element. Therefore, even if there are tolerance variations in the position of the first side wall or the size of the energy storage element in the second direction, the first side wall can still contact the second side surface via the first projection. Furthermore, because the first projection is positioned spaced apart from the main body of the first side wall, the first side wall is more likely to bend when the first projection contacts the second side surface of the energy storage element. As a result, even if the height (protrusion length) of the first projection is relatively large, the first projection can still contact the second side surface, and consequently, the energy storage element can be held in place by the first projection. In other words, even if the tolerance of the holder size or the energy storage element size in the second direction is relatively large, the holder can still apply a holding force to the energy storage element in the second direction. This allows the holder to hold the energy storage element more securely. As a result, movement (misalignment) of the energy storage element due to vibration or shock during manufacturing, use, or transportation of the energy storage device is suppressed, thereby reducing the possibility of malfunctions caused by vibration or shock. Thus, the energy storage device according to this embodiment is an energy storage device with improved reliability.

[0011] A through hole extending in the first direction may be formed in the main body at a position facing the first projection in the first direction.

[0012] With this configuration, for example, when molding a resin holder using a mold, the mold for molding the first projection can be positioned so as to penetrate the main body. In other words, it is permissible to remove the mold along the first direction. Therefore, a main body perpendicular to the first direction and a first side wall parallel to the first direction, having a first projection protruding in the second direction, can be molded with one or more molds that move in the first direction. That is, it is made easier to manufacture a holder having the first projection located at a position spaced apart from the main body on the side wall.

[0013] The power storage device further includes another power storage element disposed on the opposite side of the power storage element across the main body portion of the holder and held by the holder. The holder further has a second side wall portion facing a second side surface which is a side surface of the other power storage element in the second direction, and a second protrusion contacting the second side surface of the other power storage element is provided on the second side wall portion. When viewed from the first direction, the second protrusion may be arranged at a position not overlapping with the first protrusion in a third direction orthogonal to the first direction and the second direction.

[0014] According to this configuration, a holding force can be applied to the other power storage element by the second protrusion. Since the positions of the first protrusion and the second protrusion in the third direction do not overlap, for example, the mold for forming the first protrusion does not interfere with the formation of the second protrusion, and the mold for forming the second protrusion does not interfere with the formation of the first protrusion. Therefore, it is facilitated to manufacture the holder including the first side wall portion and the second side wall portion both having protrusions.

[0015] The holder may further have a third side wall portion facing a third side surface which is a side surface opposite to the second side surface of the power storage element, and the third side wall portion may have a flat portion in surface contact with the third side surface.

[0016] According to this configuration, the position of the power storage element pushed by the first side wall portion via the first protrusion in the second direction is restricted by the flat portion. That is, when the power storage elements held by the holders are arranged in the first direction, by aligning the positions of the flat portions of the plurality of holders in the second direction, the positions of these plurality of power storage elements in the second direction can be aligned. Thereby, for example, the positional accuracy of other members such as bus bars with respect to the power storage elements is improved, which contributes to the improvement of the reliability of the power storage device.

[0017] The present invention can also be realized as a holder for holding a power storage element according to any of the above aspects.

[0018] 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 lid 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 convenience of explanation, the Z-axis direction will be described as the vertical direction.

[0019] 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 a two-way direction parallel to the X-axis or either one of the directions. The same applies to terms related to the Y-axis and Z-axis.

[0020] 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. 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 the expression "insulation" is used, it means "electrical insulation".

[0021] (Embodiment) [1. General Description of 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] The exterior body 10 has an opening 12a at the 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 exterior body 10 comprises an exterior body main body 12 and a lid 11, with the opening 12a and the bottom wall portion 19 provided on the exterior body main body 12. The exterior body main body 12 is a bottomed rectangular cylindrical housing with the opening 12a formed therein, and it houses the energy storage element unit 20. The exterior body main body 12 has side wall portions 15 and 17 that face each other in the Y-axis direction and separate the inside from the outside of the exterior body 10. The energy storage element unit 20 is positioned between the side wall portion 17 and the side wall portion 15 in the Y-axis direction. The exterior body 10 may also include elements not shown in Figures 1 and 2, such as an exhaust pipe for discharging gas from inside the exterior body 10 to the outside.

[0026] The cover 11 is a rectangular member that closes the opening 12a of the outer casing body 12. The cover 11 is joined to the outer casing body 12 by a plurality of bolts 41, thereby fixing the cover 11 to the outer casing body 12. Specifically, through holes 43 are provided in the peripheral edge of the cover 11 through which the bolts 41 pass, and fixing holes 42 are provided in the opening peripheral edge 12b, which is the peripheral edge of the opening 12a of the outer casing body 12. The bolts 41 are screwed into the fixing holes 42 of the outer casing body 12 while passing through the through holes 43 of the cover 11. This joins the cover 11 to the opening peripheral edge 12b of the outer casing body 12.

[0027] 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) shaped 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. The shape of the electrode body is not limited.

[0028] 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 other shapes such as polygonal prisms, cylindrical shapes, elliptical prisms, or oblong cylindrical shapes.

[0029] 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.

[0030] The container body 111 has a pair of long sides 110a, a pair of short sides 110b, and a bottom surface 110c positioned opposite the lid plate 112. In this embodiment, the long side 110a is an example of a first side. Of the pair of short sides 110b, the short side 110b in the positive Y-axis direction is an example of a second side, and the short side 110b in the negative Y-axis direction is an example of a third side.

[0031] The cover plate 112 is provided with positive and negative electrode terminals 120, as well as a gas discharge valve 105. 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 such that its long side surface 110a is oriented in the alignment direction (X-axis direction), and its short side surface 110b is facing the Y-axis direction which is perpendicular to the alignment direction. In this embodiment, the X-axis direction is an example of a first direction, the Y-axis direction is an example of a second direction which is perpendicular to the first direction, and the Z-axis direction is an example of a third direction.

[0032] 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 will be 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 will be referred to as cell holder 132 to distinguish it from the others. The following description of "cell holder 130" applies to cell holders 131 and cell holder 132 unless otherwise specified.

[0033] The cell holder 130 according to this embodiment is an example of a holder for holding an energy storage element, and has the function of stabilizing the position of the energy storage element 100 by holding it. The cell holder 130 also has the function of insulating the container 110 of the energy storage element 100 from the container 110 of other energy storage elements 100 adjacent to the said energy storage element 100. The cell holder 130 is formed from one of the electrically insulating resin materials that can be used as the material for the exterior body 10. The detailed configuration of the cell holder 130 will be described later with reference to Figures 4 to 9.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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 may be appropriately determined, for example, according to the specifications required for the energy storage device 1.

[0039] In the energy storage device 1 configured in this way, the cell holder 130 that holds the energy storage element 100 has a structure that easily absorbs the size tolerances of the energy storage element 100 and the cell holder 130. As a result, the energy storage element 100 is held more stably in the cell holder 130, and consequently the reliability of the energy storage device 1 is improved. The configuration of the cell holder 130 that achieves such effects will be explained below with reference to Figures 4 to 9.

[0040] [2. Regarding the configuration of the cell holder] Figure 4 is a first perspective view showing the external appearance of the cell holder 132 and the two energy storage elements 100 according to the embodiment, and Figure 5 is a second perspective view showing the external appearance of the cell holder 132 and the two energy storage elements 100 according to the embodiment. In Figures 4 and 5, the two energy storage elements 100 held by the cell holder 132 are shown separately from the cell holder 132, and are given different reference numerals to distinguish them. Specifically, the energy storage element 100 positioned in the positive X-axis direction of the cell holder 132 is denoted as energy storage element 100A, and the energy storage element 100 positioned in the negative X-axis direction of the cell holder 132 is denoted as energy storage element 100B. When the positive X-axis direction is considered as the front, Figure 4 shows a perspective view of the cell holder 132 as seen from the front at an angle, and Figure 5 shows a perspective view of the cell holder 132 as seen from the rear at an angle. Figure 6 is a perspective cross-sectional view showing the configuration of the end portion of the cell holder 132 including the first side wall portion 135A according to the embodiment. Figure 7 is a perspective cross-sectional view showing the configuration of the end portion of the cell holder 132 including the third side wall portion 135C according to the embodiment. In Figures 6 and 7, the Y-axis end of the cell holder 132 is shown in a perspective view, cut by a plane parallel to the XZ plane. Figure 8 is a cross-sectional view showing the state in which the cell holder 132 according to the embodiment holds two energy storage elements 100. In Figure 8, the cross-sectional view along line VIII-VIII in Figure 6 is shown in a simplified manner, and the approximate arrangement range of the energy storage elements 100A and 100B is shown in the shaded area. Figure 9 is a perspective view showing the appearance of the cell holder 131 according to the embodiment. In Figure 9, the cell holder 131 is shown, which is arranged at the X-axis negative end of the energy storage element unit 20.

[0041] As shown in Figures 4 to 8, the cell holder 132 according to this embodiment has a holder body 134, a pair of side cover portions 135, a bottom cover portion 136, and a top cover portion 137. The holder body 134 is arranged along the long side surface 110a of the energy storage element 100. The pair of side cover portions 135 are connected to each of the two ends of the holder body 134 in the Y-axis direction. Each of the two side cover portions 135 covers a portion of the short side surface 110b of the energy storage element 100. The bottom cover portion 136 is connected to the Z-axis negative end of the holder body 134 and covers a portion of the bottom surface 110c of the energy storage element 100. The side cover portions 135 are connected to each of the two ends of the bottom cover portion 136 in the Y-axis direction. The top cover portion 137 is connected to the Z-axis positive end of the holder body portion 134 and covers a portion of the top surface of the cover plate 112 of the energy storage element 100.

[0042] Specifically, as shown in Figures 4, 5, and 8, each of the pair of side cover portions 135, bottom cover portion 136, and top cover portion 137 protrudes from the holder body portion 134 on both sides in the X-axis direction. As a result, the energy storage elements 100A and 100B, which are positioned on both sides of the holder body portion 134 in the X-axis direction, are surrounded by the pair of side cover portions 135, bottom cover portion 136, and top cover portion 137 in the Y-axis and Z-axis directions. In this state, the side cover portion 135 in the Y-axis positive direction of the pair of side cover portions 135 has a projection that contacts the short side 110b of each of the energy storage elements 100A and 100B.

[0043] More specifically, the side cover portion 135 at the Y-axis positive end of the cell holder 132 has a first side wall portion 135A, as shown in Figures 4 to 6 and Figure 8. When the cell holder 132 is attached to the energy storage element 100A, the first side wall portion 135A is positioned along the short side surface 110b of the energy storage element 100A, starting from the Y-axis positive end of the holder body portion 134. Thus, the first side wall portion 135A, which is positioned opposite the short side surface 110b of the energy storage element 100A, has a first projection 138A that contacts the short side surface 110b.

[0044] As shown in Figures 4, 6, and 8, the first projection 138A is positioned on the first side wall portion 135A at a distance from the holder body portion 134. In this embodiment, the first projection 138A is positioned at the end of the first side wall portion 135A in the positive X-axis direction, projecting toward the short side surface 110b of the energy storage element 100A.

[0045] The protruding length of the first projection 138A is determined by considering the size tolerances of the energy storage element 100 and the size tolerances of the cell holder 132. In other words, even when a cell holder 132 arbitrarily selected from among the multiple cell holders 132 is attached to an energy storage element 100A arbitrarily selected from among the multiple energy storage elements 100, the first projection 138A can contact the short side surface 110b of the energy storage element 100A. In this state, the first projection 138A is positioned at a distance from the holder body 134 of the first side wall portion 135A. Therefore, as shown in Figure 8, the first side wall portion 135A can be efficiently elastically deformed by the pressing force received from the energy storage element 100A, and the restoring force generated by the elastic deformation can be applied to the energy storage element 100A via the first projection 138A. As a result, the energy storage element 100A is sandwiched in the Y-axis direction by the first side wall portion 135A and the side cover portion 135 in the negative Y-axis direction (see Figures 4, 7, and 8). Consequently, the position of the energy storage element 100A inside the outer casing 10 is stabilized.

[0046] In the cell holder 132 configured in this way, the side cover portion 135 at the end in the positive Y-axis direction further has a second side wall portion 135B, as shown in Figures 4 to 6 and Figure 8. The second side wall portion 135B is positioned along the short side surface 110b of the energy storage element 100B from the end of the holder body portion 134 in the positive Y-axis direction when the cell holder 132 is attached to the energy storage element 100B. Thus, the second side wall portion 135B, which is positioned opposite the short side surface 110b of the energy storage element 100B, has a second projection 138B that contacts the short side surface 110b, as shown in Figures 5, 6 and 8. In this embodiment, since the energy storage elements 100A and 100B held by the cell holder 132 are of the same type, the second projection 138B is formed to the same size as the first projection 138A. In other words, even when a cell holder 132 arbitrarily selected from among multiple cell holders 132 is attached to a storage element 100B arbitrarily selected from among multiple storage elements 100, the second projection 138B can contact the short side surface 110b of the storage element 100B. In this state, the second projection 138B is positioned at a distance from the holder body portion 134 of the second side wall portion 135B. Therefore, as shown in Figure 8, the second side wall portion 135B can efficiently elastically deform due to the pressing force received from the storage element 100B, and the restoring force generated by the elastic deformation can be applied to the storage element 100B via the second projection 138B. As a result, the storage element 100B is clamped in the Y-axis direction by the second side wall portion 135B and the side cover portion 135 in the Y-axis negative direction (see Figures 5, 7, and 8). As a result, the position of the storage element 100B inside the outer casing 10 is stabilized.

[0047] The cell holder 131, which holds only one energy storage element 100, also has a first side wall portion 135A, similar to the cell holder 132, and a first projection 138A that contacts the short side surface 110b is positioned on the first side wall portion 135A (see Figure 9). Therefore, when the cell holder 131 is attached to the energy storage element 100, the energy storage element 100 can be clamped in the Y-axis direction by the first side wall portion 135A and the side cover portion 135 in the Y-axis negative direction. Thus, the position of the energy storage element 100 inside the outer casing 10 is stabilized. In Figure 9, a cell holder 131 is shown positioned at the X-axis negative end of the energy storage element unit 20 (see Figure 3), but a cell holder 131 positioned at the X-axis positive end of the energy storage element unit 20 also has a first side wall portion 135A with a first projection 138A. In other words, the energy storage elements 100 at the end of the multiple energy storage elements 100 arranged in the X-axis direction, which are located in the X-axis direction, are also stably held by the cell holder 131.

[0048] As described above, the energy storage device 1 according to this embodiment comprises an energy storage element 100 and a cell holder 130 that holds the energy storage element 100. The energy storage element 100 and the cell holder 130 are arranged side by side in the X-axis direction. The cell holder 130 has a holder body portion 134 that faces the first side surface (long side surface 110a), which is the side surface of the energy storage element 100 in the X-axis direction, and a first side wall portion 135A that faces the second side surface (short side surface 110b), which is the side surface of the energy storage element 100 in the Y-axis direction perpendicular to the X-axis direction. The first side wall portion 135A is arranged along the short side surface 110b from the Y-axis end of the holder body portion 134. The first side wall portion 135A is provided with a first projection 138A that is positioned spaced apart from the holder body portion 134 and contacts the short side surface 110b.

[0049] In this configuration, the first projection 138A provided on the first side wall portion 135A is positioned on the cell holder 130 at a location facing the short side surface 110b of the energy storage element 100. Therefore, even if there are tolerance variations in the position of the first side wall portion 135A in the Y-axis direction or in the size of the energy storage element 100, the first side wall portion 135A can contact the short side surface 110b via the first projection 138A. Furthermore, since the first projection 138A is positioned spaced apart from the holder body portion 134 of the first side wall portion 135A, the first side wall portion 135A is prone to bending when the first projection 138A contacts the short side surface 110b of the energy storage element 100. As a result, even if the height (protrusion length) of the first projection 138A is relatively large, the first projection 138A can still contact the short side surface 110b, thereby providing a holding effect for the energy storage element 100 by the first projection 138A. In other words, even if the tolerance of the size of the cell holder 130 or the size of the energy storage element 100 in the Y-axis direction is relatively large, the cell holder 130 can still apply a holding force to the energy storage element 100 in the Y-axis direction. This allows the cell holder 130 to hold the energy storage element 100 more securely. As a result, the position of the energy storage element 100 inside the casing 10 is stabilized. Specifically, for example, movement (misalignment) of the energy storage element 100 due to vibration or shock during manufacturing, use, or transportation of the energy storage device 1 is suppressed, thereby reducing the possibility of malfunctions caused by vibration or shock. Thus, the energy storage device 1 according to this embodiment is an energy storage device with improved reliability.

[0050] Let's consider the case where a projection is provided on the first side wall portion 135A at a position not separated from the holder body portion 134. In other words, let's consider the case where a projection is provided that is connected to both the first side wall portion 135A and the holder body portion 134. Even in this case, it is possible to bring the projection into contact with the short side surface 110b of the energy storage element 100 facing the first side wall portion 135A. However, in this case, the projection may press against the corner of the container 110 of the energy storage element 100 that is close to the holder body portion 134 (the connection portion between the short side surface 110b and the long side surface 110a). As a result, the reaction force from the projection may contain a large component in the direction that moves the energy storage element 100 away from the holder body portion 134 (positive X-axis direction). This can lead to the problem that one of the energy storage element 100 and the cell holder 130 may easily detach from the other (or be difficult to attach). This becomes more pronounced when the protruding length of the projection is increased in order to improve the pressing force on the energy storage element 100 by the projection. Furthermore, since the first side wall portion 135A and the holder body portion 134 are connected by the projection, the first side wall portion 135A is less likely to bend in the positive Y-axis direction. This is disadvantageous from the standpoint of absorbing tolerances in the size of the cell holder 130 or the energy storage element 100 due to deformation of the first side wall portion 135A. In contrast, in the cell holder 130 according to this embodiment, the first projection 138A is positioned on the first side wall portion 135A at a distance from the holder body portion 134, so the first projection 138A is less likely to come into contact with the corner of the container 110 of the energy storage element 100 that is close to the holder body portion 134. As a result, problems such as one of the energy storage element 100 and the cell holder 130 easily detaching from the other due to the pressing force from the first projection 138A are less likely to occur. Furthermore, since the first projection 138A is positioned at a distance from the holder body 134, the problem of the first projection 138A hindering the curvature of the first side wall 135A is unlikely to occur.

[0051] In this embodiment, as shown in Figures 4 to 6, a through hole 139 is formed in the holder body 134 at a position facing the first projection 138A in the X-axis direction, and the through hole penetrates in the X-axis direction.

[0052] With this configuration, for example, when molding a resin cell holder 130 using a mold, the mold for molding the first projection 138A can be positioned so as to penetrate the holder body 134. In other words, it is permissible to remove the mold along the X-axis direction. Therefore, the holder body 134 perpendicular to the X-axis direction and the first side wall 135A parallel to the X-axis direction, which has the first projection 138A protruding in the Y-axis direction, can be molded with one or more molds that move in the X-axis direction. That is, it is easier to manufacture a cell holder 130 having the first projection 138A at a position spaced apart from the holder body 134 on the first side wall 135A. By providing a through hole 139 in the holder body 134, it is also possible to reduce the amount of material used to manufacture the cell holder 130, or to lighten the cell holder 130. Note that the through hole for lightening the cell holder 130 is not limited to a position opposite the first projection 138A, but may be formed at other positions.

[0053] Among the multiple cell holders 130 provided in the energy storage device 1 according to this embodiment, the cell holder 132 positioned between two energy storage elements 100 has a configuration that stabilizes the positions of each of the two energy storage elements 100. When these two energy storage elements 100 are energy storage elements 100A and 100B (see Figures 4 and 5), the configuration of the cell holder 132 is described as follows.

[0054] In other words, the energy storage device 1 includes another energy storage element 100 (energy storage element 100B) positioned on the opposite side of the energy storage element 100A, with the holder body portion 134 of the cell holder 132 in between, and the energy storage element 100B held by the cell holder 132. The cell holder 132 further has a second side wall portion 135B that faces the short side surface 110b, which is the side surface of the energy storage element 100B in the Y-axis direction. The second side wall portion 135B is provided with a second projection 138B that contacts the short side surface 110b of the energy storage element 100B. When viewed from the X-axis direction, as shown in Figure 6, the second projection 138B is positioned so as not to overlap with the first projection 138A in the Z-axis direction which is perpendicular to the X-axis and Y-axis directions.

[0055] In this embodiment, as shown in Figure 6, three first protrusions 138A are provided on the first side wall portion 135A, arranged in the Z-axis direction at predetermined intervals. As shown in Figure 6, four second protrusions 138B are provided on the second side wall portion 135B, arranged in the Z-axis direction at predetermined intervals. Each of the four second protrusions 138B is positioned so as not to overlap with any of the three first protrusions 138A in the Z-axis direction. Specifically, when viewed from the X-axis direction, these second protrusions 138B and first protrusions 138A are arranged so that they alternate along the Z-axis direction.

[0056] This configuration allows the energy storage element 100B to be held in place by the second projection 138B. Furthermore, the positions of the first projection 138A and the second projection 138B do not overlap in the Z-axis direction. As a result, for example, the mold for forming the first projection 138A does not interfere with the forming of the second projection 138B, and the mold for forming the second projection 138B does not interfere with the forming of the first projection 138A. More specifically, the holder body 134 is provided with through holes 139 in the X-axis direction, at positions opposite each of the three first projections 138A, and through holes 139 in the X-axis direction, at positions opposite each of the four second projections 138B. Each of these through holes 139 is a hole through which a mold for forming the first projection 138A or the second projection 138B passes. In other words, the molds for forming the second projection 138B and the molds for forming the first projection 138A are arranged alternately in the Z-axis direction. As a result, protrusions (first protrusion 138A or second protrusion 138B) can be formed on the first side wall portion 135A and the second side wall portion 135B at positions spaced apart from the holder body portion 134. In this way, in the cell holder 132 according to this embodiment, the first protrusion 138A and the second protrusion 138B are positioned so as not to overlap in the Z-axis direction, thereby stabilizing the positions of the two energy storage elements 100 and facilitating the manufacture of the cell holder 132.

[0057] In this embodiment, the three first protrusions 138A are arranged in the area between the two ends (intermediate portion) of the first side wall portion 135A in the Z-axis direction. However, the first protrusions 138A may also be arranged at the ends of the first side wall portion 135A in the Z-axis direction. However, from the viewpoint of ensuring reliable insulation between the energy storage element 100 and a conductive member located in the positive X-axis direction of the energy storage element 100 (for example, the side wall portion 17 of the metal casing 10 (see Figure 2)), it is preferable that one or more first protrusions 138A are arranged in the intermediate portion of the first side wall portion 135A. Specifically, the container 110 of the energy storage element 100 may have an insulating film wrapped around a pair of long sides 110a and a pair of short sides 110b. In this case, the short sides 110b are covered with the insulating film, while the lid plate 112 and the bottom surface 110c are exposed and not covered with the insulating film. Therefore, even if the first projection 138A contacts the short side surface 110b, causing the middle portion of the first side wall 135A to bend outward (in the positive Y-axis direction), and as a result a gap is created between the middle portion of the first side wall 135A and the other cell holder 130 located in the positive X-axis direction, insulation problems caused by this gap are unlikely to occur. In other words, since the position of the gap in the Z-axis direction is within the range where the insulating film is placed, the container 110 of the energy storage element 100 and the side wall 17 (see Figure 2) of the outer casing 10 located outside it are well insulated by the insulating film. On the other hand, if the first projection 138A is placed at the Z-axis end of the first side wall 135A, the gap created by the outward bending of the first side wall 135A is located near the lid plate 112 or the bottom surface 110c of the container 110, which is not covered by the insulating film. This is undesirable from the viewpoint of ensuring good insulation between the container 110 of the energy storage element 100 and the side wall portion 17 of the outer casing 10. Therefore, in this embodiment, the multiple first protrusions 138A are arranged in the middle portion of the first side wall portion 135A in the Z-axis direction, and the multiple second protrusions 138B are arranged in the middle portion of the second side wall portion 135B in the Z-axis direction. The middle portion of the first side wall portion 135A in the Z-axis direction is, for example, the area excluding both ends of the first side wall portion 135A in the Z-axis direction, and each of these ends is about 10% of the total length of the first side wall portion 135A in the Z-axis direction. The same applies to the middle portion of the second side wall portion 135B in the Z-axis direction.

[0058] In this embodiment, the cell holder 130 has a third side wall portion 135C that faces the short side 110b of the energy storage element 100 opposite to the short side 110b that faces the first side wall portion 135A (the short side 110b in the negative Y-axis direction) (see Figures 4 to 9). The third side wall portion 135C has a flat portion 140 that contacts the short side 110b on a surface.

[0059] More specifically, as shown in Figures 4 to 8, the cell holder 132 has a pair of side cover portions 135, one of which (in the positive Y-axis direction) has a first side wall portion 135A and a second side wall portion 135B. The other side cover portion 135 (in the negative Y-axis direction) has a third side wall portion 135C at a position opposite to the first side wall portion 135A in the Y-axis direction. Similarly, the cell holder 131 also has a third side wall portion 135C at a position opposite to the first side wall portion 135A in the Y-axis direction (see Figure 9). The third side wall portion 135C has a flat portion 140 that contacts the short side surface 110b opposite to the third side wall portion 135C. In other words, each of the multiple cell holders 130 can clamp the energy storage element 100 from both sides in the Y-axis direction with the first projection 138A and the flat portion 140.

[0060] In this configuration, the position of the energy storage element 100, which is pressed against the first side wall portion 135A via the first projection 138A, in the Y-axis direction is restricted by the planar portion 140. In other words, when the energy storage elements 100 held in the cell holder 130 are arranged in the X-axis direction (see Figures 2 and 3), the positions of the planar portions 140 of the multiple cell holders 130 in the Y-axis direction can be aligned to match the positions of these multiple energy storage elements 100 in the Y-axis direction. This improves the positional accuracy of other components (such as the busbar 60) relative to the energy storage elements 100, which contributes to improving the reliability of the energy storage device 1.

[0061] Furthermore, in this embodiment, the side cover portion 135 of the cell holder 132 in the negative Y-axis direction has a fourth side wall portion 135D at a position opposite to the second side wall portion 135B in the Y-axis direction, as shown in Figures 4, 5, 7, and 8. The fourth side wall portion 135D has a flat portion 140 that contacts the short side surface 110b opposite to the fourth side wall portion 135D in a surface manner, as shown in Figures 7 and 8. In other words, the cell holder 132 according to this embodiment can clamp each of the energy storage elements 100A and 100B, which are arranged on either side of the holder body portion 134 in the X-axis direction, from both sides in the Y-axis direction by the projection (first projection 138A or second projection 138B) and the flat portion 140. Furthermore, the Y-axis position of the flat portion 140 provided on the fourth side wall portion 135D and the flat portion 140 provided on the third side wall portion 135C is the same. As a result, in this embodiment, the 12 energy storage elements 100 held by the 13 cell holders 130 can be positioned in the Y-axis direction by the planar portion 140 that makes surface contact with the short side surface 110b in the negative Y-axis direction. In other words, the positions of the 12 energy storage elements 100 in the Y-axis direction can be aligned.

[0062] [3. Regarding variations] 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.

[0063] For example, the number of first protrusions 138A located on the first side wall portion 135A does not need to be three. As long as at least one first protrusion 138A is located on the first side wall portion 135A, the cell holder 130 can hold the energy storage element 100 from both sides in the Y-axis direction, even if there are tolerance variations in the size of the energy storage element 100 or the cell holder 130. The same applies to the number of second protrusions 138B on the second side wall portion 135B; it is sufficient that at least one second protrusion 138B is located on the second side wall portion 135B.

[0064] The position of the first projection 138A on the first side wall portion 135A in the X-axis direction does not have to be at the end in the positive X-axis direction. If the first projection 138A is positioned at least at a distance from the holder body portion 134, when it comes into contact with the short side surface 110b of the energy storage element 100, it can impart a moment to the first side wall portion 135A in the direction of outward bending, and inhibiting such bending is suppressed. In other words, the first side wall portion 135A can be elastically deformed efficiently, and the resulting restoring force can be effectively used to hold the energy storage element 100. The same applies to the second projection 138B; the second projection 138B only needs to be positioned at least at a distance from the holder body portion 134 on the second side wall portion 135B.

[0065] There are no particular limitations on the shape of the first projection 138A. The first projection 138A may have an inclined surface or a curved surface to facilitate insertion of the energy storage element 100 between the pair of side cover portions 135. The first projection 138A may have a pointed tip in the protruding direction to make it easier to crush by the pressing force from the short side surface 110b of the energy storage element 100. The first projection 138A may be formed to be larger than the size shown in Figure 6, etc., when viewed from the Y-axis direction, to make it difficult to yield to the pressing force from the short side surface 110b of the energy storage element 100.

[0066] The cell holder 130 does not necessarily have an upper cover portion 137. The suppression of movement (positional displacement) of the energy storage element 100 in the positive Z-axis direction may be handled, for example, by the busbar holder 30.

[0067] The cell holder 130 does not necessarily have to be entirely made of a resin material such as PC or PP. For example, the cell holder 130 may be formed by coating the surface of a base material made of metal such as an aluminum alloy with a resin material such as PC or PP. In this case, the first projection 138A and the second projection 138B may each be entirely made of resin so that they are easily crushed by the short side 110b of the opposing energy storage element 100.

[0068] The outer casing 10 that houses the energy storage element unit 20 does not have to be the outermost housing of the energy storage device 1. For example, the outer casing 10 may be a case placed inside the outermost housing of the energy storage device 1, having a case body that houses the energy storage element 100 and a lid that closes the opening of the case body. The outer casing 10 may also be a case having one or more openings in the wall that separates the inside from the outside for heat dissipation or the like.

[0069] In the multiple energy storage elements 100 provided by the energy storage device 1, it is not necessary for a cell holder 130 (cell holder 132, see Figure 3) to be placed between every pair of adjacent energy storage elements 100. For example, if two adjacent energy storage elements 100 are electrically connected in parallel, a cell holder 130 does not need to be placed between the two energy storage elements 100. Even in this case, since each of the two energy storage elements 100 is held by one cell holder 130, it is possible to restrict the movement of the two energy storage elements 100 within the casing 10. In other words, one energy storage element 100 is held in the Y-axis direction by at least one first projection 138A and one planar portion 140 of one cell holder 130, thereby stabilizing the position of the one energy storage element 100. If a cell holder 130 is not placed between two adjacent energy storage elements 100, for example, a simple flat insulating member (spacer) may be placed as an insulating member between the containers 110 of these two energy storage elements 100. The insulation between the containers 110 of two adjacent energy storage elements 100 may be carried out, for example, by insulating sheets wrapped around each of these two containers 110.

[0070] 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".

[0071] The present invention also includes forms constructed by arbitrarily combining the components included in the above embodiments and their modified examples. [Industrial applicability]

[0072] This invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries. [Explanation of symbols]

[0073] 1. Energy storage device 100, 100A, 100B energy storage elements 110 Container 110a long side 110b short side 110c bottom 111 Container body 112 Lid plate 120 Electrode terminal 130, 131, 132 Cell holder 134 Holder body 135 Side cover section 135A First side wall part 135B Second side wall part 135C Third side wall section 135D Fourth side wall section 136 Bottom cover section 137 Top cover section 138A First protrusion 138B Second protrusion 139 Through hole 140 Plane section

Claims

1. It comprises an energy storage element and a holder for holding the energy storage element, The energy storage element and the holder are arranged side by side in the first direction. The aforementioned holder is, The main body portion facing the first side surface, which is the side surface in the first direction of the energy storage element, The first side wall portion of the energy storage element is a side surface in a second direction perpendicular to the first direction, and has a first side wall portion arranged along the second side surface from the end of the main body in the second direction, The first side wall portion is provided with a first projection that is positioned at a distance from the main body portion in the first direction and contacts the second side surface portion. Energy storage device.

2. A through hole is formed in the main body portion at a position facing the first projection in the first direction, which penetrates in the first direction. The energy storage device according to claim 1.

3. Furthermore, there is another energy storage element positioned on the opposite side of the main body of the holder from the energy storage element, and the holder is equipped with another energy storage element. The holder further has a second side wall portion facing the second side surface which is the side surface of the other energy storage element in the second direction, The second side wall portion is provided with a second projection that contacts the second side surface of the other energy storage element. When viewed from the first direction, the second projection is positioned in a location that does not overlap with the first projection in a third direction perpendicular to the first and second directions. The energy storage device according to claim 1 or 2.

4. The holder further has a third side wall portion facing the third side surface, which is the side surface of the energy storage element opposite to the second side surface, The third side wall portion has a flat portion that contacts the third side surface in a surface manner. The energy storage device according to any one of claims 1 to 3.

5. The first projection is located at the end of the first side wall portion in the first direction, The energy storage device according to any one of claims 1 to 4.

Images