JP7844808B2 - Energy storage device - Google Patents

Description

This invention relates to an energy storage device comprising an energy storage element and a spacer.

Conventionally, energy storage devices comprising energy storage elements and spacers are widely known. For example, Patent Document 1 discloses a power supply device (energy storage device) comprising a plurality of secondary battery cells (energy storage elements) arranged adjacent to each other, and separators (spacers) interposed between adjacent secondary battery cells.

International Publication No. 2018/207608

The conventional energy storage devices described above have the problem of not being able to be miniaturized or lightened. For example, in the energy storage device disclosed in Patent Document 1, spacers are placed between each energy storage element, covering almost the entire side surface of each element. This leads to an increase in the size and weight of the energy storage device due to the placement of these spacers.

This invention was made by the present inventors by focusing on the above-mentioned problems, and aims to provide an energy storage device that can be miniaturized or made lighter.

To achieve the above objective, an energy storage device according to one aspect of the present invention comprises: a first energy storage element and a second energy storage element arranged in a first direction and connected in parallel; a first spacer positioned between the first and second energy storage elements; a third energy storage element positioned between the second and third energy storage elements and connected in series with the first and second energy storage elements; and a second spacer positioned between the first and third energy storage elements. The first spacer is shorter in length than the second spacer in at least one direction: a second direction perpendicular to the first direction, and a third direction perpendicular to both the first and second directions.

According to this, in an energy storage device, the first spacer between the first and second energy storage elements, which are aligned in the first direction and connected in parallel, is shorter in length than the second spacer between the first and third energy storage elements, which are connected in series in at least one of the second and third directions. Here, when the first and second energy storage elements are connected in parallel, the potentials of the first and second energy storage elements are equivalent, so there is little need to insulate the first and second energy storage elements from each other. For this reason, there is little need to place a large spacer between the first and second energy storage elements connected in parallel, such as one that covers the entire surface of the energy storage element containers for the purpose of insulation. Therefore, it is sufficient to place a spacer between the first and second energy storage elements that compresses the energy storage elements against vibration or shock to protect them (suppressing movement of the energy storage elements or movement of the electrodes within the energy storage element containers). Therefore, a first spacer is placed between the first and second energy storage elements, which are connected in parallel, and its length in at least one of the second and third directions is shorter than that of the second spacer between the first and third energy storage elements, which are connected in series. This allows the first spacer to be made smaller, thus enabling miniaturization or weight reduction of the energy storage device.

The first spacer may be shorter in length than the second spacer in all directions perpendicular to the first direction.

According to this, by making the first spacer shorter in length than the second spacer in all directions perpendicular to the first direction, the energy storage device can be miniaturized in all directions, and its weight can also be reduced.

The first energy storage element comprises a container and electrode terminals positioned at the end of the container in the third direction. The first spacer may be shorter in length than the container in the third direction, and its center may be positioned further away from the electrode terminals than the center of the container.

In general, within the container of an energy storage element, current collectors and gaskets are positioned on the electrode terminal side of the electrode body. Therefore, the electrode body is positioned away from the electrode terminal in the third direction. For this reason, in the third direction, the first spacer is made shorter than the container of the first energy storage element, and its center is positioned further away from the electrode terminal than the center of the container. This allows the first spacer to compress the area close to the electrode body of the first energy storage element, further suppressing the movement of the electrode body within the container. Therefore, in configurations aiming for miniaturization or weight reduction of the energy storage device, the energy storage element can be effectively protected.

The second spacer may have a projection that protrudes toward the first energy storage element at a position corresponding to the first spacer in the first direction.

According to this design, the second spacer has a projection that extends toward the first energy storage element at a position corresponding to the first spacer. This allows the first energy storage element to be compressed from both sides by the first spacer and the projection. This further suppresses movement of the first energy storage element, or movement of the electrode body within the container of the first energy storage element. Therefore, in configurations aiming for miniaturization or weight reduction of the energy storage device, the energy storage element can be effectively protected.

The first spacer may be shorter in length than the containers of the first and second energy storage elements in at least one direction, and the distance between the containers of the first and second energy storage elements at a position where the first spacer is not present may be smaller than the thickness of the first spacer.

According to this, the distance between the containers of the first and second energy storage elements in the area where the first spacer is not present is smaller than the thickness of the first spacer. Therefore, in the area where the first spacer is not present, the first and second energy storage elements can be positioned closer together. Consequently, the overall width when the first and second energy storage elements are assembled can be suppressed, thus enabling miniaturization of the energy storage device.

Another embodiment of the present invention provides a power storage device comprising a first power storage element and a second power storage element arranged in a first direction and connected in parallel, and a first spacer positioned between the first power storage element and the second power storage element, wherein the first spacer is shorter in length than the containers of the first power storage element and the second power storage element in at least one direction: a second direction perpendicular to the first direction, and a third direction perpendicular to both the first and second directions, and the distance between the containers of the first power storage element and the second power storage element at a position where the first spacer is not positioned is smaller than the thickness of the first spacer.

According to this, the energy storage device includes a first spacer between the first and second energy storage elements connected in parallel, and the distance between the containers of the first and second energy storage elements in the areas where the first spacer is not present is smaller than the thickness of the first spacer. Here, as mentioned above, when the first and second energy storage elements are connected in parallel, there is little need to insulate the first and second energy storage elements, and therefore there is little need to place a large spacer that covers the entire surface of the energy storage element containers for the purpose of insulation. For this reason, a first spacer shorter in length than the containers of the first and second energy storage elements is placed between the first and second energy storage elements connected in parallel, in at least one of the second and third directions. This makes the first spacer smaller, thus enabling miniaturization or weight reduction of the energy storage device. In particular, because the distance between the containers of the first and second energy storage elements in the areas where the first spacer is not present is smaller than the thickness of the first spacer, the first and second energy storage elements can get closer to each other in the areas where the first spacer is not present. Therefore, since the width of the device when the first and second energy storage elements are assembled can be suppressed, the energy storage device can be miniaturized.

This invention can be realized not only as such an energy storage device, but also as a combination of a first spacer and a second spacer.

The energy storage device according to the present invention can be made smaller or lighter.

This is a perspective view showing the external appearance of the energy storage device according to the embodiment. This is an exploded perspective view showing the components of the energy storage device according to the embodiment when it is disassembled. This is an exploded perspective view showing the individual components when the energy storage device according to the embodiment is further disassembled. This is a perspective view showing the configuration of the energy storage element according to the embodiment. This is a front view showing the placement position of the spacer relative to the energy storage element according to the embodiment. This is a cross-sectional view showing the spacer according to the embodiment sandwiched between two energy storage elements. This is a perspective view showing the configuration of the spacer according to the embodiment. This is a front view showing the positional relationship between the energy storage element, spacer, and side plate according to the embodiment.

The following description of an energy storage device according to an embodiment (including its modifications) of the present invention will be presented with reference to the drawings. Note that the embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and manufacturing process sequences shown in the following embodiments are examples only and are not intended to limit the present invention. Dimensions in each figure are not precisely illustrated. In each figure, the same or similar components are denoted by the same reference numerals.

In the following description and drawings, the direction in which multiple energy storage elements are aligned, the direction in which the long sides of the energy storage element containers face each other, the direction in which multiple spacers are aligned, the direction in which energy storage elements are aligned with spacers, or the direction in which a pair of end plates are aligned is defined as the X-axis direction. The direction in which a pair of electrode terminals (positive and negative) of a single energy storage element face each other, the direction in which the short sides of the energy storage element container face each other, or the direction in which a pair of side plates are aligned is defined as the Y-axis direction. The direction in which the main body and lid of the energy storage device are aligned, the direction in which the container body and lid of the energy storage element are aligned, the direction in which energy storage elements are aligned with busbars, or the vertical direction is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the usage, the Z-axis direction may not be the vertical direction, but for the sake of explanation, the Z-axis direction will be described as the vertical direction below.

In the following explanation, for example, the "positive X-axis direction" refers to the direction of the X-axis arrow, and the "negative X-axis direction" refers to the opposite direction. The same applies to the Y-axis and Z-axis directions. Below, the X-axis direction may also be referred to as the first direction, the Y-axis direction as the second direction, and the Z-axis direction as the third direction. Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, may include cases where the direction or orientation is not strictly accurate. For example, when two directions are orthogonal, it means not only that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, i.e., that they include a difference of, for example, a few percent. In the following explanation, "insulation" refers to "electrical insulation."

(Embodiment)
[1. General description of the energy storage device 10]
First, a general description of the energy storage device 10 in this embodiment will be given. Figure 1 is a perspective view showing the external appearance of the energy storage device 10 according to this embodiment. Figure 2 is an exploded perspective view showing each component when the energy storage device 10 according to this embodiment is disassembled. Figure 3 is an exploded perspective view showing each component when the energy storage device 10 according to this embodiment is further disassembled. Note that Figure 3 is an exploded perspective view showing the components of the energy storage device 10 other than the outer casing 100 and the busbar 700 in disassembled form.

The energy storage device 10 is a device capable of charging with electricity from an external source and discharging electricity to the outside. In this embodiment, it has a substantially rectangular parallelepiped shape. For example, the energy storage device 10 is a battery module (battery pack) used for power storage or power supply purposes. Specifically, the energy storage device 10 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 gasoline-powered automobiles. 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 10 can also be used as a stationary battery for household or commercial use.

As shown in Figure 1, the energy storage device 10 includes an outer casing 100. As shown in Figures 2 and 3, the outer casing 100 houses multiple energy storage elements 200, multiple spacers 300 (310-340), a pair of end plates 400 (401, 402), a pair of side plates 500 (501, 502), and multiple busbars 700, etc. In addition to the above components, the energy storage device 10 may also include a busbar frame on which the busbars 700 are mounted, a circuit board for monitoring the charging and discharging states of the energy storage elements 200, electrical equipment such as fuses, relays, and connectors, and an exhaust section for exhausting gases discharged from the energy storage elements 200 to the outside of the outer casing 100.

The outer casing 100 is a box-shaped (approximately rectangular parallelepiped) container (module case) that constitutes the housing (outer shell) of the energy storage device 10. The outer casing 100 is positioned outside of the multiple energy storage elements 200, multiple spacers 300, a pair of end plates 400, a pair of side plates 500, and multiple busbars 700, etc., and fixes the multiple energy storage elements 200 etc. in predetermined positions and protects them from impacts, etc. The outer casing 100 is formed from insulating materials such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or composite materials thereof, or from metal with an insulating coating. The outer casing 100 prevents the energy storage element 200 from coming into contact with external metal components. The outer casing 100 may be made of a conductive material such as metal, as long as the insulating properties of the energy storage element 200 are maintained.

The exterior body 100 comprises an exterior body main body 110, which constitutes the main body of the exterior body 100, and an exterior body cover 120, which constitutes the cover of the exterior body 100. The exterior body main body 110 is a bottomed rectangular cylindrical housing (enclosure) with an opening, and houses the energy storage element 200, etc. The exterior body cover 120 is a flat rectangular member that closes the opening of the exterior body main body 110. The exterior body cover 120 is provided with a pair of external terminals 121 (positive and negative terminals). The energy storage device 10 charges with electricity from the outside and discharges electricity to the outside via this pair of external terminals 121.

The outer casing 100 is structured such that, after housing the energy storage element 200 and the like, the outer casing body 110 and the outer casing cover 120 are joined (bonded) to each other with an adhesive or the like to form a joint 130, thereby creating a substantially sealed interior. In this embodiment, the outer casing body 110 and the outer casing cover 120 are joined around the entire circumference of the opening of the outer casing body 110, forming a rectangular annular joint 130 that surrounds the entire circumference of the outer casing 100. Note that the joint 130 is not limited to being formed by bonding (bonding) with an adhesive; for example, it may be formed by bonding (welding) by heat sealing or ultrasonic welding, or by mechanical bonding by crimping or bolting.

The energy storage element 200 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 200 has a flat rectangular parallelepiped shape (square), and in this embodiment, eight energy storage elements 200 are arranged in the X-axis direction. The energy storage element 200 may have any shape other than a flat rectangular parallelepiped, such as a polygonal prism shape, an oblong cylinder shape, an elliptical prism shape, or a cylinder shape, and the size of the energy storage element 200 and the number of energy storage elements 200 arranged are not particularly limited. The energy storage element 200 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or it may be a capacitor. The energy storage element 200 may not be a secondary battery, but a primary battery that can use the stored electricity without the user having to charge it. The energy storage element 200 may be a battery using a solid electrolyte. The energy storage element 200 may be a pouch-type energy storage element. A detailed explanation of the configuration of the energy storage element 200 will be provided later.

The busbar 700 is a flat, rectangular member connected to the energy storage elements 200. The busbar 700 is positioned above the multiple energy storage elements 200 and is connected (joined) to the electrode terminals 240 (see Figures 2, 4, etc.) and external terminals 121 of the multiple energy storage elements 200. In other words, the busbar 700 connects the electrode terminals 240 of the multiple energy storage elements 200 to each other, and also connects the electrode terminals 240 of the end energy storage elements 200 to the external terminals 121.

In this embodiment, the busbar 700 and the electrode terminal 240 are connected (joined) by welding, and the busbar 700 and the external terminal 121 are connected (joined) by bolting via another busbar; however, the connection configuration is not particularly limited. The busbar 700 is formed from a conductive metal such as aluminum, aluminum alloy, copper, copper alloy, or nickel, or a combination thereof, or from a conductive material other than metal. In this embodiment, the busbar 700 is configured by connecting two energy storage elements 200 in parallel to form four sets of energy storage elements, and these four sets of energy storage elements are connected in series. The connection configuration of the busbar 700 is not particularly limited; the multiple energy storage elements 200 may be connected in series or in parallel in any combination.

The spacer 300 is positioned to the side of the energy storage element 200 (in the positive or negative X-axis direction) and is a component that insulates the energy storage element 200 from other components. The spacer 300 also has the function of holding the energy storage element 200 and positioning the energy storage element 200. Here, among the multiple spacers 300, the spacer 300 positioned between parallel-connected energy storage elements 200 within one set of energy storage elements is also called spacer 310, and the three spacers 300 positioned between series-connected energy storage element groups are also called spacers 320, 330, and 340. The end spacer 300 among the multiple spacers 300, that is, the spacer 300 between the end energy storage element 200 (energy storage element group) and the end plate 400, has the same configuration as the spacer 330 described above, and therefore, the end spacer 300 is also called spacer 330. Thus, the multiple energy storage elements 200 and the multiple spacers 300 (spacers 310-340) are arranged in a line along the X-axis direction (first direction).

The spacer 310 is a flat, rectangular spacer positioned between two adjacent energy storage elements 200 that are connected in parallel. The spacer 310 is made of an insulating material such as any resin material that can be used for the exterior body 100. The spacer 310 is positioned in the center of the two energy storage elements 200 and has the function of protecting the energy storage elements 200 by suppressing the movement of the energy storage elements 200 or the movement of the electrodes within the container of the energy storage elements 200 by compressing the center. For example, a spacer 310 located at the end of the X-axis positive direction among a plurality of spacers 310 is positioned between two energy storage elements 201 and 202 that are connected in parallel within a group of energy storage elements located at the X-axis positive end of a plurality of energy storage elements 200. In this embodiment, four spacers 310 are arranged to correspond to four sets of energy storage elements. However, if the number of energy storage element groups is other than four, the number of spacers 310 is appropriately changed according to the number of energy storage element groups. Furthermore, if three or more energy storage elements 200 are connected in parallel within one set of energy storage elements, the number of spacers 310 is also appropriately changed according to the number of energy storage elements 200.

The spacer 310 is joined to the energy storage element 200 by the joining members 311. In this embodiment, the joining members 311 are double-sided tape, and multiple (two) joining members 311 are arranged in the Z-axis direction on each of the two surfaces of the spacer 310 in the X-axis direction. This allows the spacer 310 to be joined (adhered) and fixed to the two energy storage elements 200 on both sides in the X-axis direction, thereby regulating the position of the two energy storage elements 200. Note that the joining members 311 may be adhesives or the like instead of double-sided tape, and the arrangement, number, and shape of the joining members 311 are not particularly limited. A detailed explanation of the configuration of the spacer 310 will be given later.

Spacers 320-340 (excluding the end spacer 330) are spacers positioned between two adjacent energy storage elements 200 that are connected in series. Spacers 320-340 have functions such as insulating the two energy storage elements 200 and protecting them from external shocks. In this embodiment, spacers 320-340 are positioned between groups of energy storage elements consisting of two parallel-connected energy storage elements 200 (between two adjacent groups of energy storage elements connected in series).

For example, among the multiple spacers 320-340 (excluding the end spacer 330), the spacers 320-340 located at the X-axis positive end are positioned between two series-connected groups of energy storage elements located at the X-axis positive end of the multiple energy storage element groups. That is, these spacers 320-340 are positioned between the energy storage element group consisting of energy storage elements 201 and 202 and the energy storage element group consisting of energy storage elements 203 and 204 (specifically, between energy storage elements 201 and 204). In this embodiment, three sets of spacers 320-340 are positioned corresponding to four sets of energy storage element groups. However, if the number of energy storage element groups is other than four, the number of spacers 320-340 is appropriately changed according to the number of energy storage element groups.

Spacer 320 is a flat, substantially rectangular spacer positioned between the two spacers 330 (and 340) and has higher rigidity than spacers 330 (and 340). Spacer 320 is made of a metal material such as aluminum, aluminum alloy, iron, stainless steel, or plated steel sheet. The material of spacer 320 is not particularly limited and may be made of a highly rigid insulating material or may be insulated. Spacer 330 is a plate-shaped, substantially rectangular insulating spacer positioned between spacers 320 (and 340) and the energy storage element 200. Specifically, spacer 330 is positioned facing the long side surface 213 of the container 210 of the energy storage element 200 (described later) and in contact with spacers 320 (and 340) and the said long side surface 213. Spacer 330 is made of an insulating material such as any resin material usable for the above-mentioned exterior body 100. Spacer 340 is a flat, rectangular spacer positioned within a recess 333 formed in the center of spacer 330 (see Figure 7). Specifically, spacer 340 is an insulating material, formed from a material with insulating properties such as glass fiber or damper material.

In this configuration, spacers 320 to 340 provide strength to protect the energy storage element 200 between the energy storage element groups, spacer 320 provides strength, the two spacers 330 provide insulation between the energy storage element groups, and the two spacers 340 provide thermal insulation between the energy storage element groups. A more detailed explanation of the configuration of spacers 320 to 340 will be given later.

As mentioned above, a spacer 330 is also placed between the end energy storage elements 200 (the group of end energy storage elements) and the end plates 400 (401, 402). This provides insulation between the end energy storage elements 200 (the group of end energy storage elements) and the end plates 400 (401, 402).

The end plate 400 and side plate 500 are restraining members that compress (restrain) the energy storage elements 200 from the outside in the direction of alignment (X-axis direction) of the multiple energy storage elements 200. In other words, the end plate 400 and side plate 500 sandwich the multiple energy storage elements 200 from both sides in that alignment direction, thereby compressing (restraining) each energy storage element 200 contained within the multiple energy storage elements 200 from both sides in that alignment direction. The end plate 400 and side plate 500 are formed from metal members such as steel or stainless steel for strength assurance, but their material is not particularly limited. For example, they may be formed from a high-strength insulating material, or the metal members may be treated with an insulating coating.

The end plates 400 are plate-shaped members (clamping members) positioned on both sides in the X-axis direction of the multiple energy storage elements 200 and the multiple spacers 300 (310-340), and they hold the multiple energy storage elements 200, etc., by sandwiching them from both sides in the direction of their alignment (X-axis direction). Here, of the pair of end plates 400, the end plate 400 on the X-axis positive direction side is also called end plate 401, and the end plate 400 on the X-axis negative direction side is also called end plate 402. In other words, the pair of end plates 401 and 402 are positioned to sandwich the multiple energy storage elements 200 and the multiple spacers 300 in the X-axis direction (the stacking direction of the electrode plates of the electrode bodies of the energy storage elements 200), and restrain them.

The side plate 500 is a plate-shaped, elongated restraining member (restraining plate) positioned in the Y-axis direction (second direction perpendicular to the first direction) of the multiple energy storage elements 200 and the multiple spacers 300 (310-340). Specifically, the side plate 500 is attached at both ends to a pair of end plates 400 (401, 402), and by connecting the pair of end plates 400, it restrains the multiple energy storage elements 200 and the multiple spacers 300 (310-340). In other words, the side plate 500 is positioned extending in the X-axis direction so as to straddle the multiple energy storage elements 200 and the multiple spacers 300, and applies a restraining force to the multiple energy storage elements 200, etc., in the direction of their alignment (X-axis direction).

In this embodiment, a pair of side plates 500 are arranged on both sides in the Y-axis direction of the multiple energy storage elements 200 and the multiple spacers 300 (310-340). In this embodiment, the pair of side plates 500 are positioned towards the positive Z-axis direction on both sides in the Y-axis direction of the multiple energy storage elements 200, etc. Each of the pair of side plates 500 is attached to the Y-axis ends of a pair of end plates 400 at both ends in the X-axis direction. As a result, the pair of side plates 500, together with the pair of end plates 400, clamp and restrain the multiple energy storage elements 200, etc., from both sides in the X-axis direction and both sides in the Y-axis direction.

Specifically, the side plates 500 are connected (joined) to the end plates 400 (401, 402) by a plurality of connecting members 500a (two in this embodiment) arranged in the Z-axis direction. In this embodiment, the connecting members 500a are bolts, which are fastened to the nuts on the end plates 400 by screwing them in. Note that the connection (joining) of the side plates 500 to the end plates 400 is not limited to fixing by bolting; they may also be joined by welding or adhesive. Of the pair of side plates 500, the side plate 500 on the Y-axis positive direction is also called side plate 501, and the side plate 500 on the Y-axis negative direction is also called side plate 502.

[2. Explanation of the energy storage element 200]
Next, the configuration of the energy storage element 200 will be described in detail. Figure 4 is a perspective view showing the configuration of the energy storage element 200 according to this embodiment. Specifically, Figure 4 shows an enlarged view of the external appearance of one of the multiple energy storage elements 200 shown in Figure 3. Since all of the multiple energy storage elements 200 have the same configuration, the configuration of one of the energy storage elements 200 will be described in detail below.

As shown in Figure 4, the energy storage element 200 comprises a container 210, a pair of electrode terminals 240 (positive and negative), and an upper gasket 250. The container 210 also contains a lower gasket, electrode bodies, a pair of current collectors (positive and negative), and an electrolyte (non-aqueous electrolyte), but these are not shown in the illustration. There are no particular restrictions on the type of electrolyte, as long as it does not impair the performance of the energy storage element 200; various types can be selected.

In addition to the above-mentioned components, the energy storage element 200 may also have spacers positioned to the side or below the electrode body, and an insulating film that encloses the electrode body, etc. Furthermore, an insulating film (such as a shrink tube) covering the outer surface of the container 210 may be placed around the container 210. The material of the insulating film is not particularly limited as long as it can ensure the necessary insulation for the energy storage element 200. Examples include insulating resins such as PC, PP, PE, PPS, PET, PBT, or ABS resin, epoxy resin, Kapton®, Teflon®, silicon, polyisoprene, and polyvinyl chloride.

The container 210 is a rectangular parallelepiped (square or box-shaped) case having a container body 220 with an opening and a container lid 230 that closes the opening of the container body 220. The container body 220 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 210, and has an opening on the Z-axis positive side. The container lid 230 is a rectangular plate-shaped member that constitutes the lid of the container 210, and is positioned extending in the Y-axis direction on the Z-axis positive side of the container body 220. The container lid 230 is provided with a gas discharge valve 231 for releasing excessive pressure inside the container 210, and an injection section 232 for injecting electrolyte into the container 210. The material of the container 210 (container body 220 and container lid 230) is not particularly limited and can be a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, but resin can also be used.

The container 210 has a structure in which, after the electrode body and other components are housed inside the container body 220, the container body 220 and the container lid 230 are joined by welding or other means to form a joint 215, thereby sealing the interior. In this embodiment, laser light is irradiated from the side of the container 210 (in the X-axis and Y-axis directions), and the container body 220 and the container lid 230 are joined by laser welding, thereby forming the joint 215. The joint 215 is a rectangular annular joint formed to surround the entire perimeter of the container 210.

With this configuration, the container 210 has a terminal arrangement surface 211 on its upper surface in the positive Z-axis direction, a pair of short sides 212 on both sides in the Y-axis direction, a pair of long sides 213 on both sides in the X-axis direction, and a bottom surface 214 on its lower surface in the negative Z-axis direction. The terminal arrangement surface 211 is a rectangular planar portion on the positive Z-axis side of the container lid 230 where the electrode terminals 240 are arranged, and is adjacent to the short sides 212 and the long sides 213. The short sides 212 are rectangular planar portions that form the short sides of the container 210, and are positioned opposite the side plate 500 in the Y-axis direction. The short sides 212 are adjacent to the long sides 213 and the bottom surface 214, and have a smaller area than the long sides 213. The long side surface 213 is a rectangular planar portion that forms the long side surface of the container 210, and is positioned opposite the long side surface 213 of the container 210 of an adjacent energy storage element 200, or the spacer 300, in the X-axis direction. The long side surface 213 is adjacent to the short side surface 212 and the bottom surface 214, and has a larger area than the short side surface 212. The bottom surface 214 is a rectangular planar portion that forms the bottom surface of the container 210, and is positioned opposite the bottom surface of the outer casing body 110 in the Z-axis direction, and is adjacent to the long side surface 213 and the short side surface 212.

The electrode terminals 240 are terminal members (positive and negative electrode terminals) of the energy storage element 200, located at the Z-axis end of the container 210 (the third direction perpendicular to the first and second directions), specifically on the container lid 230 of the container 210. The electrode terminals 240 are electrically connected to the positive and negative electrode plates of the electrode body via a current collector. In other words, the electrode terminals 240 are metal members that guide the electricity stored in the electrode body to the external space of the energy storage element 200 and introduce electricity into the internal space of the energy storage element 200 to store electricity in the electrode body. The electrode terminals 240 are made of aluminum, aluminum alloy, copper, copper alloy, or the like.

The electrode body is an energy storage element (power generation element) formed by laminating a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate has a positive electrode active material layer formed on a positive electrode base layer, which is a current collector foil made of a metal such as aluminum or an aluminum alloy. The negative electrode plate has a negative electrode active material layer formed on a negative electrode base layer, which is a current collector foil made of a metal such as copper or a copper alloy. As for the active material used in the positive electrode active material layer and the negative electrode active material layer, any known material can be used as long as it is capable of intercalating and releasing lithium ions. The separator can be a microporous sheet or nonwoven fabric made of resin. In this embodiment, the electrode body is formed by laminating electrode plates (positive electrode plate and negative electrode plate) in the X-axis direction. The electrode body may be of any form, such as a wound electrode body formed by winding electrode plates (positive electrode plate and negative electrode plate), a laminated (stacked) electrode body formed by laminating a plurality of flat electrode plates, or a bellows-type electrode body in which the electrode plates are folded in a bellows shape.

The current collectors are conductive members (positive electrode current collector and negative electrode current collector) electrically connected to the electrode terminals 240 and the electrode body. The positive electrode current collector is made of aluminum or an aluminum alloy, similar to the positive electrode base layer of the positive electrode plate, while the negative electrode current collector is made of copper or a copper alloy, similar to the negative electrode base layer of the negative electrode plate. The upper gasket 250 is positioned between the container lid 230 and the electrode terminals 240, insulating and sealing the space between the container lid 230 and the electrode terminals 240. The lower gasket is positioned between the container lid 230 and the current collector, insulating and sealing the space between the container lid 230 and the current collector. The upper gasket 250 and the lower gasket may be made of any material that provides insulation.

Thus, the current collector and lower gasket are positioned inside the container 210 at the Z-axis positive end. Therefore, in the Z-axis direction, the electrode body's center is positioned in the Z-axis negative direction relative to the center of the container 210. The center of the electrode body is the centroid of the surface of the electrode body facing the X-axis direction (or, if that surface is not flat, the surface obtained by projecting the electrode body onto the YZ plane). The center of the container 210 is the centroid of the surface of the container 210 facing the X-axis direction (in this embodiment, the long side surface 213).

[3. Explanation of Spacer 300]
Next, the configuration of the spacers 300 (310-340) will be described in detail. Since each of the spacers 310-340 provided in the energy storage device 10 has the same configuration, the following description will focus on spacer 310 located at the end in the positive X-axis direction, and the pair of spacers 320-340 located at the end in the positive X-axis direction.

As described above, the energy storage elements 201 to 204 are arranged in a line along the X-axis. Energy storage element 204 is positioned so as to sandwich energy storage element 201 between energy storage element 202, and energy storage element 203 is positioned so as to sandwich energy storage element 204 between energy storage element 201. Energy storage elements 201 and 202 are connected in parallel, and energy storage elements 203 and 204 are connected in series with energy storage elements 201 and 202. Spacer 310 is placed between energy storage elements 201 and 202. Spacers 320 and 330 are placed between energy storage elements 201 and 204. Specifically, spacer 320 is placed between the two spacers 330, and spacer 330 is placed between energy storage element 201 or energy storage element 204 and spacer 320.

Here, energy storage element 201 is an example of a first energy storage element, energy storage element 202 is an example of a second energy storage element, and energy storage element 204 is an example of a third energy storage element. Spacer 310 is an example of a first spacer, and spacer 330 is an example of a second spacer. In other words, the first energy storage element (energy storage element 201) and the second energy storage element (energy storage element 202) are aligned in the X-axis direction (first direction) and connected in parallel. The third energy storage element (energy storage element 204) is positioned between the first energy storage element (energy storage element 201) and the second energy storage element (energy storage element 202), and is connected in series with the first energy storage element (energy storage element 201) and the second energy storage element (energy storage element 202). The first spacer (spacer 310) is positioned between the first energy storage element (energy storage element 201) and the second energy storage element (energy storage element 202). The second spacer (spacer 330) is placed between the first energy storage element (energy storage element 201) and the third energy storage element (energy storage element 204).

[3.1 Explanation of Spacer 310]
First, the configuration of the spacer 310 will be described in detail. Figure 5 is a front view showing the placement position of the spacer 310 relative to the energy storage element 200 according to this embodiment. Specifically, Figure 5 shows the configuration when the spacer 310 is placed on the energy storage element 200 and viewed from the X-axis direction. Figure 6 is a cross-sectional view showing the spacer 310 according to this embodiment sandwiched between two energy storage elements 200 (201 and 202). Specifically, Figure 6(a) shows the configuration when the state in which two energy storage elements 200 (201 and 202) are placed on both sides of the spacer 310 is cut by a plane parallel to the XZ plane, and Figure 6(b) shows the configuration when the state in Figure 6(a) is compressed from both sides in the X-axis direction. In other words, Figure 6(a) shows the state before the multiple energy storage elements 200 and multiple spacers 300 are compressed (restrained) by the end plate 400 and side plate 500, and Figure 6(b) shows the state after compression (restraint). Note that in Figure 6, the components inside the container 210 of the energy storage element 200 are not shown.

As shown in Figures 3 and 5, the spacer 310 is shorter in length than the container 210 of the energy storage element 201 and the container 210 of the energy storage element 202 in at least one direction, either the Y-axis direction (second direction) or the Z-axis direction (third direction). In this embodiment, the spacer 310 is shorter in length than the container 210 of the energy storage element 201 and the container 210 of the energy storage element 202 in both the Y-axis direction and the Z-axis direction. Specifically, the spacer 310 is shorter in length than the container 210 of the energy storage element 201 and the container 210 of the energy storage element 202 in all directions perpendicular to the X-axis direction (first direction).

As shown in Figure 3 and Figure 8 (described later), the spacer 330 has the same size as the container 210 of the energy storage elements 200 (201, 202) when viewed from the X-axis direction. Therefore, the spacer 310 is shorter in length than the spacer 330 in at least one direction: the Y-axis direction (second direction) and the Z-axis direction (third direction). In this embodiment, the spacer 310 is shorter in length than the spacer 330 in both the Y-axis and Z-axis directions. Specifically, the spacer 310 is shorter in length than the spacer 330 in all directions perpendicular to the X-axis direction (first direction).

The spacer 310 is positioned at the center of the long side 213 of the container 210 for the energy storage element 201, and at the center of the long side 213 of the container 210 for the energy storage element 202. Specifically, the spacer 310 is positioned on the long side 213 at a location corresponding to the electrode body of the energy storage element 201 (or energy storage element 202). In this embodiment, as described above, the electrode body's center in the Z-axis direction is located in the negative Z-axis direction (away from the electrode terminal 240) from the center of the container 210. Therefore, the spacer 310 is positioned at a location where its center is further away from the electrode terminal 240 than the center of the container 210. The center of the spacer 310 is the centroid of the surface of the spacer 310 facing the energy storage element 201 (or energy storage element 202) (the surface facing the X-axis direction). As described above, the center of the container 210 of the energy storage element 201 (or energy storage element 202) is the center of gravity of the surface of the container 210 facing the X-axis direction, that is, the center of gravity of the surface of the container 210 of the energy storage element 201 (or energy storage element 202) facing the spacer 310 (in this embodiment, the long side surface 213).

Specifically, as shown in Figure 5, the spacer 310 is positioned such that, when viewed from the X-axis direction, the distance A between the spacer 310 and the terminal placement surface 211 of the container 210 is greater than the distance B between the spacer 310 and the bottom surface 214 of the container 210. In the Y-axis direction, since the electrode body's center is positioned at the same location as the center of the container 210, the spacer 310's center is also positioned at the same location as the center of the container 210.

Furthermore, it is preferable that the spacer 310 be positioned within the flat portion of the electrode body of the energy storage element 201 (or energy storage element 202) when viewed from the X-axis direction. For example, if the electrode body is a stacked type with stacked electrode plates, it is preferable that the spacer 310 be formed with a size and shape that allows it to be positioned within the entire area of the electrode body when viewed from the X-axis direction. If the electrode body is a flat wound type with a flat portion and a curved portion formed by winding electrode plates, it is preferable that the spacer 310 be formed with a size and shape that allows it to be positioned within the flat portion of the electrode body when viewed from the X-axis direction.

As shown in Figure 6, when the spacer 310 is compressed from both sides in the X-axis direction while sandwiched between the two energy storage elements 200 (201 and 202), the spacer 310 bites into the center of the long side surface 213 of the container 210 of the two energy storage elements 200 (201 and 202). As a result, as shown in Figure 6(b), the container 210 of energy storage element 201 and the container 210 of energy storage element 202 move closer to each other in the position where the spacer 310 is not placed. Therefore, the distance between the container 210 of energy storage element 201 and the container 210 of energy storage element 202 in the position where the spacer 310 is not placed becomes smaller than the thickness of the spacer 310. If this distance is not constant, the maximum value of this distance can be adopted. If the thickness is not constant, the maximum value of the thickness can be adopted. In other words, the maximum value of the distance between the containers 210 of energy storage elements 201 and 202 is smaller than the maximum thickness of the spacer 310.

In other words, the distance between the containers 210 of the energy storage elements 201 and 202 (the long sides 213) in positions where the spacer 310 is not placed is smaller than the thickness of the spacer 310 in at least one direction (in this embodiment, both directions) of the spacer 310 in the Y-axis and Z-axis directions. Furthermore, the distance between the containers 210 of the energy storage elements 201 and 202 (the long sides 213) in the portion that does not overlap with the spacer 310 when viewed from the X-axis direction is smaller than the distance between the containers 210 of the energy storage elements 201 and 202 (the long sides 213) in the portion that overlaps with the spacer 310 when viewed from the X-axis direction. That is, the distance between the containers 210 of the energy storage elements 201 and 202 (the long sides 213) is smaller than the thickness of the spacer 310 in all directions perpendicular to the X-axis direction of the spacer 310.

[3.2 Explanation of Spacers 320-340]
Next, the configuration of the spacers 320 to 340 will be described in detail. Figure 7 is a perspective view showing the configuration of the spacers 320 to 340 according to this embodiment. Specifically, Figure 7 shows a set of spacers 320 to 340 arranged between two energy storage elements 200 (two sets of energy storage element groups). Figure 8 is a front view showing the positional relationship between the energy storage element 200, the spacers 320 to 340, and the side plate 500 according to this embodiment. Specifically, Figure 8 shows the configuration when the spacers 320 to 340 and the side plate 500 are assembled to the energy storage element 200, as viewed from the X-axis positive direction. Note that in Figure 8, for the sake of explanation, the illustration of the spacer 330 in the X-axis positive direction is omitted, and the cross-section of the side plate 500 is shown as it is cut by a plane parallel to the YZ plane.

As shown in these figures, the spacer 320 has a shape that is symmetrical with respect to the XZ plane at the center position in the Y-axis direction (or a shape that is rotationally symmetrical when rotated around an axis passing through the center position and parallel to the Z-axis direction). The spacer 320 has a pair of recesses 321, two through holes 322, two through holes 323, a through hole 324, and a through hole 325.

The recess 321 is a rectangular recess provided on both sides of the spacer 320 in the Y-axis direction, recessed in the Y-axis direction and extending in the Z-axis direction. The through-hole 322 is a circular through-hole that penetrates the spacer 320 in the X-axis direction, provided at a position near the positive Y-axis and positive Z-axis direction from the center of the spacer 320, and at a position near the negative Y-axis direction from the Z-axis negative end of the spacer 320. The through-hole 322 is positioned to correspond to the two protrusions 336 on the spacer 330 in the negative X-axis direction, as described later. The through-hole 323 is a circular through-hole that penetrates the spacer 320 in the X-axis direction, provided at a position near the negative Y-axis and positive Z-axis direction from the center of the spacer 320, and at a position near the positive Y-axis direction from the Z-axis negative end of the spacer 320. The through-hole 323 is positioned to correspond to the two protrusions 336 on the spacer 330 in the positive X-axis direction.

The through-hole 324 is a circular through-hole that penetrates the spacer 320 in the X-axis direction, located at both the Y-axis negative and Z-axis positive ends of the spacer 320. The through-hole 324 is positioned to correspond to the projection 337 on the spacer 330 in the X-axis negative direction, as described later. The through-hole 325 is a circular through-hole that penetrates the spacer 320 in the X-axis direction, located at both the Y-axis positive and Z-axis positive ends of the spacer 320. The through-hole 325 is positioned to correspond to the projection 337 on the spacer 330 in the X-axis positive direction.

The spacer 340 has a through hole 341, two through holes 342, and two through holes 343. The through hole 341 is a circular through hole located in the center of the spacer 340, penetrating the spacer 340 in the X-axis direction. The through hole 341 is positioned to correspond to the protrusion 335 of the spacer 330, which will be described later. The through holes 342 are circular through holes located at the Y-axis positive end and Z-axis positive end of the spacer 340, and at the Y-axis negative end and Z-axis negative end of the spacer 340, penetrating the spacer 340 in the X-axis direction. The through holes 342 are positioned to correspond to the two protrusions 336 of the spacer 330 in the X-axis negative direction. The through-holes 343 are circular through-holes that penetrate the spacer 340 in the X-axis direction, located at the Y-axis negative end and Z-axis positive end of the spacer 340, and at the Y-axis positive end and Z-axis negative end of the spacer 340. The through-holes 343 are positioned to correspond to the two protrusions 336 on the spacer 330 in the X-axis positive direction.

The two spacers 330, positioned on either side of spacer 320 in the X-axis direction, have the same shape but are rotated 180° relative to each other around the Z-axis. Each spacer 330 includes a spacer body 331, a pair of spacer side walls 332, a recess 333, a protrusion 334, a convex portion 335, two projections 336, a projection 337, a projection 338, and a through hole 339.

The spacer body 331 is a flat, rectangular portion that constitutes the body of the spacer 330, and is arranged parallel to the YZ plane. In this embodiment, the spacer body 331 is arranged to cover almost the entire long side surface 213 of the container 210. The spacer side wall 332 is a plate-shaped portion that protrudes in the X direction from both ends of the spacer body 331 in the Y direction and extends in the Z direction. In this embodiment, the spacer side wall 332 is arranged along the short side surface 212 of the container 210. The spacer side wall 332 has a recessed shape corresponding to the recess 321 of the spacer 320.

The recess 333 is located in the center of the spacer body 331 and is a rectangular recess that is recessed in the X-axis direction. The recess 333 is located opposite the spacer 320 (340). The protrusion 334 is formed on the surface of the spacer body 331 opposite to the recess 333 and is a rectangular portion that protrudes in the X-axis direction from the center of the spacer body 331. The protrusion 334 protrudes toward the long side surface 213 of the container 210 and is located in contact with the long side surface 213. Specifically, the protrusion 334 is located at a position that sandwiches the container 210 with the spacer 310, and at a position corresponding to the spacer 310 in the X-axis direction (first direction), and compresses the container 210 together with the spacer 310 (see Figure 3). In order for the protrusion 334 to compress the container 210 evenly from both sides in the X-axis direction with the spacer 310, it is preferable that the amount of protrusion from the spacer body 331 in the X-axis direction is half the thickness of the spacer 310.

The protrusion 335 is a cylindrical projection that is flattened in the direction of projection and protrudes from the center of the recess 333 toward the spacer 320 (340). The protrusion 335 is positioned to correspond to the through hole 341 of the spacer 340 and is inserted into the through hole 341. The projection 336 is a cylindrical projection that is flattened in the direction of projection and protrudes toward the spacer 320 (340) and is positioned around the protrusion 335 in the recess 333. The projection 336 of the spacer 330 in the negative X-axis direction is positioned to correspond to the through hole 342 of the spacer 340 and the through hole 322 of the spacer 320 and is inserted into the through hole 342 and the through hole 322. The projection 336 of the spacer 330 in the positive X-axis direction is positioned to correspond to the through hole 343 of the spacer 340 and the through hole 323 of the spacer 320 and is inserted into the through hole 343 and the through hole 323.

The projection 337 is a cylindrical projection that is flattened in the direction of projection and is located at the Z-axis positive end of the spacer body 331, projecting toward the spacer 320. The projection 337 of the spacer 330 in the X-axis negative direction is located at the Y-axis negative end of the spacer body 331, corresponding to the through hole 324 of the spacer 320, and is inserted into the through hole 324. The projection 337 of the spacer 330 in the X-axis positive direction is located at the Y-axis positive end of the spacer body 331, corresponding to the through hole 325 of the spacer 320, and is inserted into the through hole 325. The projection 338 and the through hole 339 are located side by side in the Y-axis direction at the Y-axis center and Z-axis negative end of the spacer body 331. The projection 338 on one spacer 330 is positioned to correspond to the through-hole 339 on the other spacer 330 and is a cylindrical projection that protrudes toward the through-hole 339. The through-hole 339 is a circular through-hole into which the projection 338 is inserted.

With the above configuration, spacer 340 is placed in the recess 333 of spacer 330, and spacers 320 to 340 are assembled. Then, spacers 320 to 340 and the side plate 500 are assembled to the energy storage element 200.

As a result, as shown in Figure 8, the spacer 320 is positioned to protrude from the edge of the container 210 of the energy storage element 200 (201, 204, etc.) in the Y-axis direction (second direction), when viewed from the X-axis direction (first direction), on the edge side different from the electrode terminal 240 of the energy storage element 201. In this embodiment, the spacer 320 protrudes from both edges of the container 210 in the Y-axis direction (second direction), when viewed from the X-axis direction (first direction), on the edges side different from the electrode terminal 240 (a surface different from the terminal arrangement surface 211). Specifically, the spacer 320 protrudes from both of the pair of short sides 212 of the container 210 when viewed from the X-axis direction. In this embodiment, at both ends in the Y-axis direction, the entire Y-axis end of the spacer 320 protrudes from the short side 212. Note that the spacer 320 may have a configuration in which a portion of its Y-axis end (for example, the portion of the recess 321) does not protrude from the short side 212, but it is preferable that both Z-axis ends of the Y-axis end protrude from the short side 212.

Spacer 320 is shorter in length than the container 210 of the energy storage element 200 (201, 204, etc.) in the Z-axis direction (third direction). Spacer 330 has the same size as the container 210 of the energy storage element 200 (201, 204, etc.) in the Z-axis direction. Therefore, spacer 330 is longer in length than spacer 320 in the Z-axis direction (third direction). In this embodiment, spacer 320 is positioned so that it does not protrude from the container 210 and spacer 330 at both ends in the Z-axis direction.

Specifically, the spacer 320 is positioned closer to the positive Z-axis direction relative to the container 210 and spacer 330. In other words, in the Z-axis direction, the center of the spacer 320 is positioned further in the positive Z-axis direction than the center of the container 210 (and the center of the spacer 330). As a result, in the Z-axis direction (third direction), the center of the spacer 320 is positioned closer to at least one of the electrode terminals 240 of the energy storage element 200 (201, 204, etc.), the gas discharge valve 231, the joint portion 215 of the container 210, and the joint portion 130 of the outer casing 100 than the center of the container 210. In this embodiment, in the Z-axis direction, the center of the spacer 320 is positioned closer to all of the electrode terminals 240, the gas discharge valve 231, the joint portion 215, and the joint portion 130 (see Figure 1) than the center of the container 210 (and the center of the spacer 330).

The side plates 500 (501, 502) are positioned within the recesses 321 of the spacer 320 (and the recesses in the spacer sidewalls 332 of the spacer 330). Therefore, in the Z-axis direction (third direction), the center of the side plate 500 is positioned in the same direction as the center of the spacer 320 relative to the center of the container 210 (the positive Z-axis direction). In other words, in the Z-axis direction, the center of the side plate 500 is positioned closer to at least one (all in this embodiment) of the electrode terminals 240, gas discharge valve 231, joint 215, and joint 130 than to the center of the container 210 (and the center of the spacer 330). Note that the Y-axis width of the outer casing body 110 at both ends of the spacer 320 in the Y-axis direction and at the positions corresponding to the side plates 500 is greater than the Y-axis width at the Z-axis negative end (see Figures 1 and 2).

[4. Explanation of Effects]
As described above, according to the energy storage device 10 of the embodiment of the present invention, a spacer 310 (first spacer) is placed between two energy storage elements 200 (for example, energy storage elements 201 and 202 (first energy storage element and second energy storage element)) that are aligned in the X-axis direction (first direction) and connected in parallel. A spacer 330 (second spacer) is placed between two energy storage elements 200 (for example, energy storage elements 201 and 204 (first energy storage element and third energy storage element)) that are connected in series. The spacer 310 is shorter in length than the spacer 330 in at least one direction of the Y-axis direction (second direction) and the Z-axis direction (third direction). Here, when the two energy storage elements 200 are connected in parallel, the potentials of the two energy storage elements 200 are equivalent, so there is little need to insulate the two energy storage elements 200 from each other. When two energy storage elements 200 are connected in parallel, it is difficult to prevent a heat chain between the two elements 200, and therefore there is little need to insulate the space between them. For this reason, there is little need to place a large spacer that covers the entire surface of the container 210 between two parallel-connected energy storage elements 200 for the purpose of insulation or heat insulation. Therefore, it is sufficient to place a spacer between the two energy storage elements 200 that compresses the energy storage elements 200 against vibration or shock to protect them (suppressing the movement of the energy storage elements 200 or the movement of the electrodes of the energy storage elements 200 within the container 210). For this reason, a spacer 310 is placed between two parallel-connected energy storage elements 200 that is shorter in length in at least one direction (Y-axis and Z-axis) than the spacer 330 between two series-connected energy storage elements 200. This makes the spacer 310 smaller, thus enabling miniaturization or weight reduction of the energy storage device 10.

In the energy storage device 10, by making the spacer 310 shorter in length than the spacer 330 in all directions perpendicular to the X-axis, the energy storage device 10 can be miniaturized in all directions and its weight can also be reduced.

In general, within the container 210, the energy storage element 200 is positioned with a current collector and gaskets on the electrode terminal 240 side of the electrode body. Therefore, the electrode body is positioned towards the opposite side of the electrode terminal 240 in the Z-axis direction. For this reason, the spacer 310 is made shorter than the container 210 of the energy storage element 200 in the Z-axis direction, and the center of the spacer 310 is positioned further away from the electrode terminal 240 than the center of the container 210. This compresses the area of the energy storage element 200 closest to the electrode body, further suppressing movement of the electrode body within the container 210. Thus, in configurations aiming for miniaturization or weight reduction of the energy storage device 10, the energy storage element 200 can be effectively protected.

The spacer 330 has a projection 334 that protrudes toward the energy storage element 200 at a position corresponding to the spacer 310. This allows the spacer 310 and the projection 334 to compress the energy storage element 200 from both sides in the X-axis direction. This further suppresses movement of the energy storage element 200, or movement of the electrode body within the container 210 of the energy storage element 200. Therefore, in a configuration aimed at miniaturizing or lightening the energy storage device 10, the energy storage element 200 can be effectively protected.

Because the distance between the containers 210 of the two energy storage elements 200 (for example, energy storage elements 201 and 202) in the area where the spacer 310 is not placed is smaller than the thickness of the spacer 310, the two energy storage elements 200 can be brought closer together in the area where the spacer 310 is not placed. Therefore, the increase in the width in the X-axis direction when the two energy storage elements 200 are assembled can be suppressed, thus enabling miniaturization of the energy storage device 10.

In the energy storage device 10, a spacer 320 is placed between a plurality of energy storage elements 200 (for example, energy storage elements 201 and 204) arranged in the X-axis direction (first direction). The spacer 320 protrudes from the Y-axis direction (second direction) edge of the container 210 of the energy storage element 200, on the side opposite to the electrode terminals 240, when viewed from the X-axis direction, and is shorter in length than the container 210 in the Z-axis direction (third direction). By having the spacer 320 protrude from the Y-axis direction edge of the container 210 of the energy storage element 200, on the side opposite to the electrode terminals 240, the energy storage elements 200 can be protected from impacts from the Y-axis direction. However, having the spacer 320 protrude from the Y-axis direction edge of the container 210 of the energy storage element 200 presents the problem of increasing the size and weight of the spacer 320. In particular, increasing the thickness of the spacer 320 or forming it from metal to improve its strength would increase its size and weight. Therefore, the spacer 320 is formed to be shorter than the container 210 of the energy storage element 200 in the Z-axis direction. This suppresses the increase in size or weight of the spacer 320. Thus, in the energy storage device 10, the increase in size or weight can be suppressed while protecting the energy storage element 200.

In the energy storage device 10, the spacer 320 protrudes from both edges of the container 210 of the energy storage element 200 in the Y-axis direction, thereby effectively protecting the energy storage element 200 from impacts in the Y-axis direction.

In the energy storage element 200, a configuration that protects the electrode terminals 240, the current collector, the gas discharge valve 231, or the joint portion 215 of the container 210 is preferred. In the energy storage device 10, a configuration that protects the joint portion 130 of the outer casing 100 is preferred. Therefore, the spacer 320 is positioned so that its center is closer to at least one of the electrode terminals 240, current collector, gas discharge valve 231, joint portion 215 of the container 210, and joint portion 130 of the outer casing 100 of the energy storage device 10, than to the center of the container 210 of the energy storage element 200. This effectively protects at least one of the energy storage element 200 and the outer casing 100.

If the energy storage device 10 includes a side plate 500, the center of the side plate 500 is also positioned so that it is in the same direction as the center of the spacer 320 relative to the center of the container 210 of the energy storage element 200. This allows the side plate 500 to effectively protect at least one of the following: the electrode terminals 240 of the energy storage element 200, the current collector, the gas discharge valve 231, the joint 215 of the container 210, and the joint 130 of the outer casing 100 of the energy storage device 10.

In addition to the spacer 320, which is intended to protect the energy storage element 200, an insulating spacer 330 is placed to insulate the energy storage element 200. In this embodiment, since the spacer 320 is made of a conductive material such as metal, by placing the spacer 330 between the energy storage element 200 (e.g., energy storage element 201) and the spacer 320, insulation between the energy storage element 200 and the spacer 320 can be achieved. Even if the spacer 320 is made of an insulating material, if the spacer 320 is not configured to insulate between two energy storage elements 200 (e.g., energy storage elements 201 and 204), insulation between the two energy storage elements 200 can be achieved by placing the spacer 330. These measures allow for the protection of the energy storage element 200 in the energy storage device 10.

By making the insulating spacer 330 longer than the spacer 320, the insulation of the energy storage element 200 can be improved. In this embodiment, since the spacer 320 is made of a conductive material such as metal, making the spacer 330 longer than the spacer 320 can improve the insulation between the energy storage element 200 (e.g., energy storage element 201) and the spacer 320. However, even when the spacer 320 is made of an insulating material, since the spacer 320 is shorter than the container 210 in the Z-axis direction, the spacer 320 may not be able to adequately insulate the two energy storage elements 200 (e.g., energy storage elements 201 and 204). Therefore, by arranging a spacer 330 that is longer than the spacer 320, the insulation between the two energy storage elements 200 can be improved. These measures allow for the protection of the energy storage element 200 in the energy storage device 10.

[5. Explanation of Variant Examples]
Although the energy storage device 10 according to this embodiment has been described above, the present invention is not limited to the above embodiment. 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.

For example, in the above embodiment, the spacer 320 is configured to protrude from both edges (both short sides 212) in the Y-axis direction of the container 210 of the energy storage element 200 when viewed from the X-axis direction. However, it is not necessary for the spacer 320 to protrude from one edge (one short side 212) in the Y-axis direction of the container 210. In other words, the spacer 320 only needs to protrude from at least one edge in the Y-axis direction of the container 210 when viewed from the X-axis direction. Alternatively, the spacer 320 may protrude from the Z-axis edge of the container 210 when viewed from the X-axis direction, on the side opposite to the electrode terminals 240 of the energy storage element 200 (bottom surface 214), and may be shorter in length than the container 210 of the energy storage element 200 in the Y-axis direction. In other words, in the above embodiment, the Y-axis direction was used as an example of a second direction, but the Z-axis direction may also be used as a second direction. Furthermore, the spacer 320 may have a configuration other than those described above, and the energy storage device 10 does not need to be equipped with a spacer 320. In this case, it is sufficient to place one spacer 330 (and 340) between the series-connected energy storage elements 200.

In the above embodiment, the spacer 320 and side plate 500 are positioned closer to the positive Z-axis direction relative to the container 210 and spacer 330 of the energy storage element 200. However, they may also be positioned towards the center in the Z-axis direction or closer to the negative Z-axis direction.

In the above embodiment, the spacer 310 is shorter than the container 210 of the energy storage element 200 in all directions perpendicular to the X-axis direction. However, it may be longer than the container 210 in any direction perpendicular to the X-axis direction. Alternatively, the spacer 310 may be longer than the container 210 of the energy storage element 200 in all directions perpendicular to the X-axis direction.

In the above embodiment, the spacer 310 is positioned so that its center is further away from the electrode terminal 240 than the center of the container 210 of the energy storage element 200. However, in the Z-axis direction, it may be positioned at the same location as the center of the container 210, or closer to the electrode terminal 240 than the center of the container 210.

In the above embodiment, the spacer 330 has a pair of spacer side walls 332, a recess 333, and a protrusion 334, but it does not have to have these, and its shape is not particularly limited. The arrangement, number, size, and shape of the convex portion 335, projections 336, 337, 338, and through-hole 339 on the spacer 330 are also not particularly limited. The same applies to other spacers 300.

In the above embodiment, the distance between the containers 210 of the energy storage elements 200 in positions where the spacer 310 is not placed is smaller than the thickness of the spacer 310. However, depending on the degree of compression by the end plate 400 and the side plate 500, the distance between the containers 210 may be approximately the same as the thickness of the spacer 310. Alternatively, the distance between the containers 210 may become larger than the thickness of the spacer 310 due to bulging in the center of the container 210.

In the above embodiment, all spacers 310 are assumed to have the above configuration, but it is not necessary for any of the spacers 310 to have the above configuration. The same applies to the other spacers 300.

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

This invention can be realized not only as such an energy storage device, but also as a combination of a first spacer (spacer 310) and a second spacer (spacer 330).

This invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries.

10 Energy storage device 100 Outer casing 121 External terminals 130, 215 Joints 200, 201, 202, 203, 204 Energy storage element 210 Container 211 Terminal arrangement surface 212 Short side 213 Long side 214 Bottom surface 231 Gas discharge valve 240 Electrode terminals 300, 310, 320, 330, 340 Spacer 311 Joining member 321, 333 Recess 322, 323, 324, 325, 339, 341, 342, 343 Through hole 331 Spacer body 332 Spacer side wall 334 Protruding part 335 Convex part 336, 337, 338 Projection 400, 401, 402 End plate 500, 501, 502 Side Plates; 700 Busbar

Claims (4)

A first energy storage element and a second energy storage element are arranged in a first direction and connected in parallel,
A first spacer is disposed between the first energy storage element and the second energy storage element,
A third energy storage element is positioned between the first energy storage element and the second energy storage element, and is connected in series with the first and second energy storage elements.
A second spacer, separate from the first spacer, is positioned between the first energy storage element and the third energy storage element.
The first spacer is shorter in length than the second spacer in at least one of the second direction perpendicular to the first direction and the third direction perpendicular to both the first and second directions.
The first spacer is in the shape of a flat plate,
The second spacer has a projection that protrudes toward the first energy storage element at a position corresponding to the first spacer in the first direction.
Energy storage device. A first energy storage element and a second energy storage element are arranged in a first direction and connected in parallel,
A first spacer is disposed between the first energy storage element and the second energy storage element,
A third energy storage element is positioned between the first energy storage element and the second energy storage element, and is connected in series with the first and second energy storage elements.
A second spacer is disposed between the first energy storage element and the third energy storage element,
The first spacer is shorter in length than the second spacer in at least one of the second direction perpendicular to the first direction and the third direction perpendicular to both the first and second directions.
The first spacer is shorter in length than the second spacer in all directions perpendicular to the first direction.
The first spacer is in the shape of a flat plate,
The second spacer has a projection that protrudes toward the first energy storage element at a position corresponding to the first spacer in the first direction.
Energy storage device. The first energy storage element comprises a container and electrode terminals located at the end of the container in the third direction.
The energy storage device according to claim 1 or 2, wherein the first spacer is shorter in length than the container in the third direction, and its center is positioned further away from the electrode terminals than the center of the container. The first spacer is shorter in length than the container of the first energy storage element and the container of the second energy storage element in at least one direction.
The energy storage device according to any one of claims 1 to 3 , wherein the distance between the container of the first energy storage element and the container of the second energy storage element at a position where the first spacer is not placed is smaller than the thickness of the first spacer.