Energy storage module

Abstract

This prevents the constraining load from becoming too high due to the expansion of the energy storage device. [Solution] The energy storage module 100 comprises a plurality of energy storage devices, a restraining member 110, and a spacer 120. The plurality of energy storage devices have a pair of opposing wide surfaces 11b1 and 11b2, and are arranged with the wide surfaces 11b1 and 11b2 facing each other. The restraining member 110 is configured to restrain the plurality of energy storage devices in the direction in which the wide surfaces 11b1 and 11b2 of the plurality of energy storage devices are arranged facing each other. The spacer 120 is positioned between the energy storage device located at the first end 2a in the direction in which the plurality of devices are arranged and the restraining member 110, and its thickness decreases when a load greater than a predetermined load is applied along the direction in which the energy storage devices are arranged.

Description

Technical Field

[0001] This disclosure relates to a power storage module.

Background Art

[0002] Secondary batteries such as lithium-ion secondary batteries are known to expand over time when repeatedly charged and discharged. Japanese Unexamined Patent Application Publication No. 2022-13634 discloses a technology related to a battery pack. The battery pack disclosed in this publication includes a plurality of single cells, a plurality of plate-shaped spacers, and an insulating member provided between the spacers separately from the spacers. The plurality of single cells have a rectangular outer shape and are constrained in a predetermined arrangement direction. Between the single cells, two plate-shaped spacers are arranged so as to face each other. The insulating member has a higher hardness than the spacer and is provided so as to contact each of the two spacers sandwiching the insulating member at a plurality of locations between the spacers arranged between the single cells. The insulating member has a thickness in the arrangement direction such that the insulating member does not penetrate the spacer even when the distance between the two spacers becomes minimum due to an increase in the restraining load. Thereby, in addition to the expansion of the single cell due to charge and discharge, when the restraining load increases due to the expansion of the single cell due to aging deterioration, the insulating member having a higher hardness than the spacer sinks into the spacer, suppressing an excessive increase in the restraining load more than expected.

[0003] Japanese Unexamined Patent Application Publication No. 2022-77843 discloses a battery module including a laminate in which a plurality of battery cells having a negative electrode containing lithium metal or a lithium-containing metal are laminated. Such a battery module has a fixing member provided at the center in the lamination direction. This fixing member fixes the battery cells located on both sides of the fixing member in the lamination direction.

[0004] Japanese Patent Publication No. 2023-116166 discloses a plurality of battery cells arranged in a first direction. The housing that houses the plurality of battery cells is formed such that the electrode terminals (positive terminal and negative terminal) are arranged along a second direction perpendicular to the first direction. In such a battery module, the side surface of the housing can directly support the stack of battery cells. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-13634 [Patent Document 2] Japanese Patent Publication No. 2022-77843 [Patent Document 3] Japanese Patent Publication No. 2023-116166 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, the inventors of this invention want to improve the situation where the constraining load on the energy storage module becomes too high due to the expansion of the energy storage device. [Means for solving the problem]

[0007] The energy storage module disclosed herein comprises a plurality of energy storage devices, a restraining member, and a spacer. The plurality of energy storage devices have a pair of opposing wide surfaces and are arranged with these wide surfaces facing each other. The restraining member is configured to restrain the plurality of energy storage devices in the direction in which they are arranged with their wide surfaces facing each other. The spacer is positioned between the energy storage device located at the first end of the plurality of devices in the direction in which they are arranged and the restraining member. The thickness of the spacer decreases when a load greater than a predetermined load is applied along the direction in which they are arranged.

[0008] This energy storage module improves upon the problem of excessively high constraint loads on the energy storage module due to the expansion of the energy storage device. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic perspective view of an energy storage module. [Figure 2] Figure 2 is a schematic side view of an energy storage module. [Figure 3] Figure 3 is a schematic perspective view of a lithium-ion battery. [Figure 4] Figure 4 is a schematic longitudinal cross-sectional view of a lithium-ion battery. [Figure 5] Figure 5 is a schematic exploded view of the electrode assembly. [Figure 6] Figure 6 is a schematic plan view showing one preferred embodiment (a fractured spacer) of the spacer disclosed herein. [Figure 7] Figure 7 is a schematic longitudinal cross-sectional view showing a preferred embodiment of the spacer disclosed herein (a fracture-type spacer) before operation. [Figure 8] Figure 8 is a schematic longitudinal cross-sectional view showing the state after operation of a preferred embodiment of the spacer disclosed herein (a fracture-type spacer). [Figure 9] Figure 9 is a schematic plan view showing one preferred embodiment of the spacer disclosed herein (a spacer with a protruding portion for fitting). [Figure 10] Figure 10 is a schematic plan view showing one preferred embodiment of the spacer disclosed herein (a recessed spacer of the fitting type). [Figure 11] Figure 11 is a schematic longitudinal cross-sectional view showing a state before operation of a preferred embodiment of the spacer disclosed herein (a fitted spacer). [Figure 12] Figure 12 is a schematic longitudinal cross-sectional view showing the state after operation of a preferred embodiment of the spacer disclosed herein (a fitted spacer). [Figure 13] Figure 13 is a schematic side view showing an energy storage module according to another embodiment disclosed herein. [Figure 14] FIG. 14 is an explanatory diagram for explaining the movement of the spacer of the power storage module according to another embodiment disclosed herein. [Figure 15] FIG. 15 is a perspective view schematically showing the pack case type power storage module disclosed herein.

Mode for Carrying Out the Invention

[0010] Hereinafter, the power storage module in the present disclosure will be described. In the following drawings, members and parts having the same function are denoted by the same reference numerals for description. Also, the dimensional relationships (length, width, thickness, etc.) in each figure do not reflect the actual dimensional relationships. In the following description, the reference numerals L, R, U, and D in the drawings represent the left, right, top, and bottom of the power storage module and the lithium ion secondary battery 1 described later. Also, it is defined as the vertical direction (height direction Y), the horizontal direction (width direction X), and the front-rear direction (column direction Z). However, these are merely directions for convenience of explanation and do not limit the installation form of the power storage module in any way.

[0011] <Definition of Terms> In this specification, the “power storage device” is a concept that includes a device in which a charge carrier moves between a pair of electrodes (positive electrode and negative electrode) to cause a charge-discharge reaction. That is, the power storage device includes batteries such as secondary batteries (for example, lithium ion secondary batteries, nickel hydrogen batteries, nickel cadmium batteries), and capacitors (physical batteries) such as lithium ion capacitors and electric double layer capacitors. Hereinafter, the present embodiment will be described by taking a lithium ion secondary battery, which is one of typical power storage devices, as an example. Also, in this specification, the “lithium ion secondary battery” refers to a power storage device that uses lithium ions as charge carriers and realizes repeated charge and discharge by the movement of charges associated with lithium ions between the positive and negative electrodes.

[0012] In this specification, "energy storage module" refers to an assembly of energy storage devices incorporating multiple energy storage devices. Furthermore, in this specification, "cell" or "single battery" refers to individual energy storage devices that can be electrically connected to each other to constitute an energy storage module.

[0013] In this specification, when a numerical range is described as "A to B (where A and B are arbitrary numbers)," it means "greater than or equal to A and less than or equal to B," and also encompasses the meanings of "greater than A and less than B," "greater than A and less than or equal to B," and "greater than or equal to A and less than B."

[0014] <Energy storage module 100> Figure 1 is a schematic perspective view of the energy storage module 100. Figure 2 is a schematic side view of the energy storage module 100. Figure 2 is a view of Figure 1 from a different direction (the left side (L direction)).

[0015] As shown in Figure 1, the energy storage module 100 comprises a plurality of energy storage devices, a spacer 120, and a restraining member 110. In the example shown in Figure 1, the energy storage device is a lithium-ion secondary battery 1, and will be referred to as a lithium-ion secondary battery 1 as appropriate hereafter.

[0016] <Multiple energy storage devices (Lithium-ion secondary battery 1)> In this embodiment, as shown in Figures 1 and 2, a plurality of lithium-ion secondary batteries 1 are arranged in a predetermined direction (in this embodiment, the column direction Z). In Figure 1, the front side in the column direction Z is defined as the front (symbol F), and the depth side is defined as the back (symbol Rr). Adjacent lithium-ion secondary batteries 1 have their wide surfaces 11b1 and 11b2 facing each other. That is, the plurality of lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other. As a result, the plurality of lithium-ion secondary batteries 1 are arranged with their orientations alternating so that the positive electrode external terminals 14 and negative electrode external terminals 15 are alternately arranged. The positive electrode external terminal 14 of one adjacent lithium-ion secondary battery 1 and the negative electrode external terminal 15 of the other lithium-ion secondary battery 1 can be electrically connected to each other by a metal busbar (not shown). However, this does not limit the arrangement or connection method of the lithium-ion secondary batteries 1. The lithium-ion secondary batteries 1 can be connected in series or in parallel.

[0017] <Energy storage device: Lithium-ion secondary battery 1> Figure 3 is a schematic perspective view of the lithium-ion secondary battery 1. Figure 4 is a schematic longitudinal cross-sectional view of the lithium-ion secondary battery 1. Figure 4 is a schematic longitudinal cross-sectional view of the lithium-ion secondary battery 1 along the line IV-IV in Figure 3. In addition, in Figure 4, a portion of the electrode body 20 is shown transparently so that the structure of the electrode body 20 can be seen.

[0018] <Case 10> As shown in Figure 3, in this embodiment, the case 10 has a rectangular parallelepiped shape, specifically a flattened rectangular shape. The case 10 comprises a main body 11 that houses the electrode body 20 and electrolyte (not shown), and a sealing plate 12 (lid) that seals the opening of the main body 11. The main body 11 and the sealing plate 12 are sealed (airtight) by welding, such as by laser welding. The material of the case 10 can be the same as that conventionally used in this type of energy storage device, and there are no particular restrictions. As an example, the material of the case 10 can be a lightweight metal material with good thermal conductivity, such as aluminum. However, it is also possible to change the configuration of the case 10. For example, a flexible laminate film may be used as the case.

[0019] In this embodiment, the main body 11 of the case 10 is composed of a rectangular and elongated bottom surface 11a, a pair of wide surfaces 11b1 and 11b2 extending from the bottom surface 11a and facing each other, and a pair of narrow surfaces 11c1 and 11c2. For convenience, in the following description, one of the pair of opposing wide surfaces 11b1 and 11b2 will be referred to as the "first surface" and the other wide surface 11b2 will be referred to as the "second surface".

[0020] The case 10 is also provided with a safety valve 13 and an electrolyte injection hole (not shown). The safety valve 13 is a thin-walled valve designed to release internal pressure when the internal pressure of the case 10 rises above a predetermined level. The electrolyte injection hole is a hole for injecting electrolyte. Since the electrolyte injection hole becomes unnecessary after the electrolyte is injected, it can be sealed by laser welding or the like. Alternatively, the electrolyte injection hole can be sealed by attaching a stopper.

[0021] External positive terminal 14 and negative terminal 15 are provided exposed to the outside of the case 10. These external terminals are electrically connected to the electrode body 20 housed inside the case 10 via the positive internal terminal 16 or the negative internal terminal 17. The positive terminal 14 and the negative terminal 15 are made of metal. For example, aluminum or an aluminum-based alloy may be used for the positive terminal 14. For example, copper or a copper alloy may be used for the negative terminal 15.

[0022] The positive electrode internal terminal 16 and the negative electrode internal terminal 17 are made of metal. For the positive electrode internal terminal 16, from the viewpoint of improving the bonding strength with the positive electrode tab 31c (or the portion 31a where the positive electrode active material layer is not formed), for example, aluminum or an aluminum alloy may be used. For the negative electrode internal terminal 17, from the viewpoint of improving the bonding strength with the negative electrode tab 41c (or the portion 41a where the negative electrode active material layer is not formed), for example, copper or a copper alloy may be used.

[0023] In this embodiment, the positive external terminal 14 and the negative external terminal 15 are attached to the sealing plate 12 via a gasket 18. The positive internal terminal 16 and the negative internal terminal 17 are attached to the back surface (inside) of the sealing plate 12 via an insulator 19. The gasket 18 and the insulator 19 may be made of insulating material with excellent chemical resistance and weather resistance.

[0024] <Electrolyte> Case 10 contains the electrolyte. For example, the electrolyte is a liquid electrolyte that is liquid at room temperature (25°C). Conventional non-aqueous electrolytic solutions can be used as the electrolyte without any particular limitations. Carbonates are preferred as the non-aqueous electrolyte.

[0025] <Electrode body 20> Case 10 houses the electrode body 20. The electrode body 20 has a positive electrode 30 and a negative electrode 40. Figure 5 is a schematic exploded view of the electrode body 20. In this embodiment, the electrode body 20 is a wound electrode body in which a strip-shaped positive electrode 30 and a strip-shaped negative electrode 40 are stacked along the length direction via strip-shaped separators 50a and 50b, and wound around a winding axis WL set in the width direction of the positive electrode 30. In this embodiment, the electrode body 20 is provided with a positive electrode tab 31c at one end in the winding axis direction. A negative electrode tab 41c is provided at the other end in the winding axis direction. That is, along the winding axis WL, a positive electrode tab 31c is provided at one end of the electrode body 20, and a negative electrode tab 41c is provided at the other end in that direction. Note that the electrode body 20 is not limited to a wound electrode body, but may also be a laminated electrode body in which positive and negative electrodes are stacked alternately via separators. Furthermore, in the laminated electrode body, a strip-shaped separator may be bent in a zigzag pattern while sandwiching the positive electrode and the negative electrode, in a so-called zigzag-fold form.

[0026] <Positive electrode 30> As shown in Figure 5, the positive electrode 30 comprises a rectangular positive electrode current collector foil 31 and a positive electrode active material layer 32 formed on the surface of the positive electrode current collector foil 31. The positive electrode active material layer 32 is capable of reversibly intercepting and releasing charge carriers (e.g., lithium ions). That is, the positive electrode active material layer 32 contains a positive electrode active material that can release charge carriers during charging and intercept charge carriers during discharge. The positive electrode active material layer 32 may be formed on one side or both sides (in this case, both sides) of the positive electrode current collector foil 31. The positive electrode 30 may also have a portion 31a where the positive electrode active material layer 32 is not formed and the positive electrode current collector foil 31 is exposed. The portion 31a where the positive electrode active material layer is not formed is provided at one end of the electrode body 20. In this embodiment, a positive electrode protective layer 31b is provided on the edge of the positive electrode active material layer 32, on the positive electrode current collector foil 31 (more specifically, the portion 31a where the positive electrode active material layer is not formed). The positive electrode protective layer 31b is a layer that protects the portion 31a where the positive electrode active material layer is not formed, and may be a layer containing an inorganic filler (e.g., alumina).

[0027] The material of the positive electrode current collector foil 31 may be any known positive electrode current collector foil used in this type of energy storage device, and is not particularly limited. The material of the positive electrode current collector foil 31 may be, for example, aluminum or an aluminum alloy. As the positive electrode active material of the positive electrode active material layer 32, a positive electrode active material used in the positive electrode of a general lithium-ion secondary battery 1 can be used. Lithium composite metal oxides include LiCoO2, LiNiO2, LiFeO2, and LiNi x Co y Mn 1-x-y O2(NCM), LiNi 0.5 Mn 1.5 O4, LiSa 0.8 Co 0.15 Al 0.05 Examples include O2(NCA), LiCrMO4, LiMn2O4, and LiFePO4(LFP). These positive electrode active materials may be used individually or in combination of two or more. The positive electrode active material layer 32 may also contain various additives such as binders, conductive additives, inorganic fillers, or thickeners.

[0028] <Negative electrode 40> As shown in Figure 5, the negative electrode 40 comprises a rectangular negative electrode current collector foil 41 and a negative electrode active material layer 42 formed on the surface of the negative electrode current collector foil 41. The negative electrode active material layer 42 is capable of reversibly intercepting and releasing charge carriers (e.g., lithium ions). That is, the negative electrode active material layer 42 contains a negative electrode active material that can intercept charge carriers during charging and release charge carriers during discharge. The negative electrode active material layer 42 may be formed on one side or both sides (in this case, both sides) of the negative electrode current collector foil 41. The negative electrode 40 may also have a portion 41a where the negative electrode active material layer 42 is not formed and the negative electrode current collector foil 41 is exposed. The portion 41a where the negative electrode active material layer is not formed is provided at one end of the electrode body 20.

[0029] The material of the negative electrode current collector foil 41 is not particularly limited and may be any known negative electrode current collector foil used in this type of energy storage device. For example, the material of the negative electrode current collector foil 41 may be copper or a copper alloy. As the negative electrode active material of the negative electrode active material layer 42, a negative electrode active material used in the negative electrode of a general lithium-ion secondary battery can be used. Specifically, examples of negative electrode active materials include soft carbon (easily graphitizable carbon), amorphous carbon materials, graphite, hard carbon (difficult to graphitize carbon), carbon nanotubes and other carbon materials, silicon compounds, etc. One of these negative electrode active materials may be used alone, or two or more may be used in combination. The negative electrode active material layer 42 may also contain various additives such as binders, conductive additives, inorganic fillers, or thickeners.

[0030] <Separators 50a, 50b> The separators 50a and 50b in this embodiment are porous sheets having insulating properties. However, the shape and dimensions of the separators 50a and 50b can be appropriately determined according to the design of the energy storage device and are not particularly limited. Typically, since the separators 50a and 50b insulate the positive electrode 30 and the negative electrode 40, the dimensions of the separators 50a and 50b are larger than those of the positive electrode 30 and the negative electrode 40. The material of the separators 50a and 50b can be any commercially available separator used in this type of energy storage device and are not particularly limited. For example, the material of the separators 50a and 50b can preferably be a polyolefin such as polyethylene or polypropylene, polyester, cellulose, or a resin such as polyamide.

[0031] <Restraining member 110> As shown in Figures 1 and 2, the restraining member 110 is a member that restrains a plurality of lithium-ion secondary batteries 1 (energy storage devices) and a spacer 120. The restraining member 110 is configured to restrain a plurality of lithium-ion secondary batteries 1 in a direction (in this embodiment, the column direction Z) in which the plurality of lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other. In this embodiment, as shown in Figures 1 and 2, the restraining member 110 has a pair of end plates (a first end plate 112a and a second end plate 112b). The end plates are positioned at the start and end points in the direction in which the plurality of lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other. More specifically, the restraining member 110 has a first end plate 112a positioned on one end side of the arranged lithium-ion secondary batteries 1 (i.e., the first end 2a of the stack 2, the front F side lithium-ion secondary battery 1a in this embodiment). Furthermore, the restraining member 110 has a second end plate 112b positioned on the other end of the arranged lithium-ion secondary battery 1 (i.e., the second end 2z of the laminate 2, or the rear Rr side lithium-ion secondary battery 1z in this embodiment). In this specification, the term "laminated body" referring to an energy storage device means an assembly of cells in which multiple cells are arranged in one direction.

[0032] The restraining member 110 further includes a side bar 113 and a bottom plate 111. In this embodiment, as shown in Figure 1, the side bar 113 spans between the first end plate 112a and the second end plate 112b. In this restraining member 110, the pair of end plates (first end plate 112a and second end plate 112b) are connected to the side bar 113 by a number of screws 114. However, the first end plate 112a, the second end plate 112b, and the side bar 113 can also be connected by adhesive or welding. The side bar 113 supports the narrow surfaces 11c1 and 11c2 of the lithium-ion secondary batteries 1 in order to arrange the lithium-ion secondary batteries 1 along the column direction Z. The bottom plate 111 is positioned in contact with the bottom surfaces 11a of the multiple lithium-ion secondary batteries 1.

[0033] The materials of the first end plate 112a and the second end plate 112b, the side bar 113, and the bottom plate 111 are not particularly limited. These materials can be selected from metal or resin, etc. Also, the materials of each component may be the same or different. From the viewpoint of the strength of the restraining member 110 and applying an appropriate load to the lithium-ion secondary battery 1 and the spacer 120, these materials are preferably metal. Also, the shapes of the first end plate 112a and the second end plate 112b, the side bar 113, and the bottom plate 111 are not particularly limited. For example, the side bar 113 may also be plate-shaped. In this embodiment, the first end plate 112a and the second end plate 112b and the bottom plate 111 are rectangular and have a predetermined thickness (for example, a thickness that allows multiple screws 114 to be driven in).

[0034] In this embodiment, the restraining member 110 restrains the spacer 120 and the laminate 2 in the direction in which the multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other (here, the column direction Z). This allows the restraining member 110 to apply a predetermined load to the spacer 120 and the lithium-ion secondary batteries 1 along the column direction Z. The restraining load applied by the restraining member 110 is not particularly limited, as long as it does not significantly impair the effects of the technology of this disclosure. Energy storage devices such as lithium-ion secondary batteries may expand in volume over time, for example, by repeatedly charging and discharging. If the restraining load is too high in the initial state (before expansion) of the energy storage device, the increase in load due to the expansion of the energy storage device becomes significant, making it easier for the electrolyte to be pushed out from the electrode body. From this viewpoint, the upper limit of the initial restraining load is preferably 10kN or less, more preferably 8kN or less, and even more preferably 6kN or less. Furthermore, if the initial restraining load is too low, the module's durability decreases (typically, it becomes vulnerable to external forces such as shocks and vibrations). Also, the distance between electrodes increases, and the resistance increases. For this reason, the lower limit of the initial restraining load is preferably 4kN or more, more preferably 4.7kN or more, and even more preferably 5kN or more.

[0035] Incidentally, sealed energy storage devices like the one described above tend to expand and contract due to charging and discharging, and over time, the inside expands, causing the case 10 to bulge. Furthermore, when the sealed energy storage device is large and has a high energy density, the tendency for the case 10 to bulge becomes stronger. Consequently, in energy storage modules equipped with such energy storage devices, the confinement pressure tends to gradually increase. As a result, the sides of multiple energy storage devices (more specifically, the flattened surfaces 21 of the electrode bodies 20 inside the energy storage devices) are strongly pressed against each other. This causes the electrolyte impregnated in the electrode bodies 20 inside the energy storage devices to be pushed out from between the electrodes. This can lead to uneven distribution of the electrolyte inside the energy storage device (typically, non-uniformity in the concentration distribution of the charge carrier (e.g., lithium ions)).

[0036] Based on these findings, the inventors propose a novel configuration for an energy storage module. The energy storage module 100 disclosed herein includes a spacer 120. The spacer 120 is positioned between an energy storage device located at the first end 2a in the direction in which the multiple energy storage devices are arranged with their wide surfaces 11b1 and 11b2 facing each other, and a restraining member 110. The thickness of the spacer 120 decreases when a load greater than a predetermined load is applied along the direction in which the multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other.

[0037] <Spacer 120> The spacer 120 is provided in contact with the lithium-ion secondary battery 1. In this embodiment, the spacer 120 is positioned between the lithium-ion secondary battery 1a on the first end 2a side and the first end plate 112a. However, the positioning of the spacer 120 is not limited to this. The spacer 120 may be positioned between the lithium-ion secondary battery 1z on the second end 2z side and the second end plate 112b. Alternatively, the spacer 120 may be positioned between the lithium-ion secondary batteries 1.

[0038] Furthermore, when multiple cells are arranged in one direction, as in the energy storage module 100, the load tends to concentrate at the end in the direction in which the cells are arranged (here, the first end 2a and / or the second end 2z). This is because the increased thickness due to the expansion of each cell is biased towards one end or the other. Also, not all cells expand uniformly, and the degree of expansion (thickness after expansion) may differ from cell to cell. Even in such cases, by placing the spacer 120 at the end, the spacer 120 can absorb the expansion of multiple cells. Therefore, preferably, the spacer 120 is placed at one of the ends of the multiple lithium-ion secondary batteries 1 arranged in a row (in other words, the first end 2a and / or the second end 2z of the laminate 2). In addition, placement at the end is easier to install than placement between cells. In this embodiment, as a preferred example of the placement of the spacer 120, it is provided between the lithium-ion secondary battery 1a on the first end 2a side and the first end plate 112a. This makes it easier to restrict the direction of the load to one direction (here, the first end 2a side). This makes it easier for the spacer 120 to absorb the expansion of multiple lithium-ion secondary batteries 1, and simplifies the setting of the operating pressure. As a result, the dimensional displacement of the spacer 120 can be stabilized.

[0039] The material of the spacer 120 disclosed herein is not particularly limited, as it may be any material conventionally used for this type of spacer (e.g., inter-cell separators). Typically, the material of the spacer 120 may be a metal or a resin. Examples of metals include aluminum or aluminum-based alloys. Examples of resins include polyolefin resins, polyethylene resins, and ethylene propylene rubber. Of these, from the viewpoint of suitably obtaining the effects of the technology disclosed herein, the material of the spacer 120 is preferably a metal, and particularly preferably aluminum or an aluminum-based alloy. Furthermore, from the viewpoint of safety, it is preferable that the spacer 120 is insulating. The insulating resin material mentioned above may also be used, and in the case of metal materials, it is preferable that an insulating coating is applied.

[0040] The spacer 120 is a rectangular plate-shaped member. In this embodiment, the spacer 120 is provided facing the first surface 11b1 of the lithium-ion secondary battery 1a on the first end 2a side. The thickness of the spacer 120 is not particularly limited as long as the effects of the technology of this disclosure are achieved. However, if the thickness of the spacer 120 is too large, the volumetric energy efficiency of the energy storage module 100 will decrease. Therefore, when the average thickness of each lithium-ion secondary battery 1 included in the energy storage module 100 is taken as 100% in the state before restraint (before applying load), the upper limit of the thickness of the spacer 120 is preferably 5% or less, more preferably 4.5% or less, and even more preferably 4% or less. Also, if the thickness of the spacer 120 is too small, the reduction in restraint pressure will be small when the thickness decreases due to a load larger than a predetermined load being applied. Therefore, the lower limit of the thickness of the spacer 120 is preferably 1% or more, more preferably 1.2% or more, and even more preferably 1.5% or more.

[0041] The spacer 120 disclosed herein is displaced in dimensions in the direction in which multiple energy storage devices are arranged with their wide surfaces 11b1 and 11b2 facing each other (here, the column direction Z). More specifically, it is configured such that its thickness decreases when a load greater than a predetermined load is applied along the column direction Z. The predetermined load is not particularly limited as long as the effects of the technology of this disclosure are achieved. The predetermined load can be set appropriately depending on the purpose (e.g., application of an energy storage module). As the load applied in the column direction Z increases, the electrolyte tends to be pushed out from the electrode body 20. From this viewpoint, the upper limit of the predetermined load is preferably, for example, 90kN or less, more preferably 85kN or less, and even more preferably 80kN or less. The lower limit is preferably, for example, 10kN or more, more preferably 50kN or more, and even more preferably 70kN or more. Furthermore, the predetermined loads allow for slight deviations due to human or mechanical errors, for example (e.g., ±10%, ±5%, and ±1%). In other words, the term "predetermined load" in this specification can be interpreted as being modified by words such as "substantially," "approximately," and "about."

[0042] In the embodiment described above, the energy storage module 100 comprises a plurality of lithium-ion secondary batteries 1, a spacer 120, and a restraining member 110. The spacer 120 is positioned at the first end 2a in the direction in which the wide surfaces 11b1 and 11b2 of the plurality of energy storage devices are arranged facing each other. The spacer 120 is also positioned between the lithium-ion secondary batteries 1 and the restraining member 110. The thickness of the spacer 120 decreases when a load greater than a predetermined load is applied along the direction in which the wide surfaces 11b1 and 11b2 of the plurality of energy storage devices are arranged facing each other. With this spacer 120, when the restraining pressure of the energy storage module increases and reaches a predetermined load, the restraint can be released and the restraining pressure can be suitably reduced. As a result, the restraining pressure of the energy storage module 100 does not become too high, and the amount of electrolyte pushed out from the electrode body 20 can be reduced. This makes it possible to suppress liquid unevenness of the electrolyte in the energy storage device (typically, non-uniformity of the concentration distribution of charge carriers (e.g., lithium ions)). As a result, the deposition of metals that act as charge carriers (e.g., metallic lithium) inside the electrode body is suppressed, and the performance degradation of the energy storage device (e.g., cycle capacity maintenance rate) can be prevented. Furthermore, because the energy storage module 100 of this disclosure has a small number of components, it has a high volumetric energy density as a module.

[0043] In the embodiment described above, the lithium-ion secondary battery 1 includes an electrode body 20 and a rectangular case 10. The restraining member 110 includes a first end plate 112a positioned on the first end 2a side in the direction in which the wide surfaces 11b1 and 11b2 of the plurality of energy storage devices are arranged facing each other, and a second end plate 112b positioned on the second end 2z side, which is on the opposite side from the first end 2a side. The restraining member 110 also includes a side bar 113 spanning between the first end plate 112a and the second end plate 112b. This makes it easier to arrange the lithium-ion secondary batteries 1 along the column direction Z. As a result, the dimensional displacement of the spacer 120 of this disclosure can be suitably exhibited. In addition, it becomes easier to protect the lithium-ion secondary batteries 1 from external shocks and vibrations to the energy storage module 100.

[0044] Furthermore, the thickness of the spacer 120 after its thickness has decreased (i.e., after its dimensions have shifted) is not particularly limited, as long as the effects of the technology of this disclosure are achieved. However, from the viewpoint of suitably obtaining such effects, it is preferable that the spacer 120 be formed such that its thickness decreases in proportion to the number of cells (here, lithium-ion secondary battery 1). When a predetermined load is reached, it is preferable that the thickness of the spacer 120 decreases by approximately [(number of cells arranged in a predetermined direction) × 0.5 to 2.0] mm. Moreover, it is more preferable that the thickness of the spacer 120 decreases by approximately [(number of cells arranged in a predetermined direction) × 0.5 to 1.5] mm, and even more preferable that it decreases by approximately [(number of cells arranged in a predetermined direction) × 0.5 to 1.0] mm. This allows for efficient release of the confining pressure.

[0045] <Suitable examples of spacers> A preferred example of the spacer 120 described above will be explained in more detail below. As stated above, the present disclosure provides a spacer 120 used in an energy storage module, which is placed between the restraining member 110 and / or the energy storage device, and whose thickness decreases when a load greater than a predetermined load is applied in a predetermined direction. Here, the predetermined direction is the same direction in which a plurality of lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other.

[0046] (Example 1: Breakable Spacer 220) Preferred examples of the spacer 120 as described above include those shown in Figures 6 to 8. Figure 6 is a schematic plan view showing a preferred embodiment of the spacer 120 disclosed herein (a breakable spacer 220). Figure 7 is a schematic longitudinal cross-sectional view showing the state of the preferred embodiment of the spacer 120 disclosed herein (a breakable spacer 220) before operation. Figure 8 is a schematic longitudinal cross-sectional view showing the state of the preferred embodiment of the spacer 120 disclosed herein (a breakable spacer 220) after operation. In this example, the breakable spacer 220 has a first surface 221a (the front surface) and a second surface 221b which is the back surface of the first surface 221a. Figure 6 is a plan view of the breakable spacer 220 as seen from the first surface 221a side. Figures 7 and 8 show the constrained lithium-ion secondary battery 1a and the breakable spacer 220 as seen from a direction perpendicular to the column direction Z (here, the width direction X). Figure 8 shows the fracture-type spacer 220 in Figure 7 with a load greater than a predetermined load applied along the column direction Z, resulting in a reduced thickness.

[0047] As shown in Figure 6, the breakable spacer 220 includes a protrusion 230, an outer edge 231, and a joint 232. The protrusion 230 is a region that extends from the outer edge 231 toward the front in Figure 6. In this case, the protrusion 230 is a region that extends from the outer edge 231 in the column direction Z toward the opposing first end plate 112a. As shown in Figure 7, in this embodiment, the protrusion 230 is in contact with the first end plate 112a by being restrained by the restraining member 110. The outer edge 231 is a region that surrounds the protrusion 230. The outer edge 231 is in contact with the wide surface 11b1 of the lithium-ion secondary battery 1a by being restrained by the restraining member 110. However, the orientation of the breakable spacer 220 is not limited to this. The protrusion 230 may abut against the lithium-ion secondary battery 1a, and the outer edge 231 may abut against the first end plate 112a. In other words, the first surface 221a of the breakable spacer 220 may face the first end plate 112a, and the second surface 221b may face the wide surface 11b1 of the lithium-ion secondary battery 1a. Alternatively, the second surface 221b of the breakable spacer 220 may face the first end plate 112a, and the first surface 221a may face the wide surface 11b1 of the lithium-ion secondary battery 1a. The joint 232 is the region connecting the protrusion 230 and the outer edge 231. The thickness of the joint 232 can typically be formed to be thinner than the thickness of the protrusion 230 or the outer edge 231. The thicknesses of the protrusion 230 and the outer edge 231 may be the same or different.

[0048] The movement of the fracture-type spacer 220 described above will now be explained. As shown in Figure 7, before the lithium-ion secondary battery 1 expands, the protrusion 230 of the fracture-type spacer 220 is in contact with the first end plate 112a. Also, the outer edge 231 of the fracture-type spacer 220 is in contact with the wide surface 11b1 of the lithium-ion secondary battery 1a. In this example, there is a gap 400 between the second surface 221b of the protrusion 230 and the wide surface 11b1 of the lithium-ion secondary battery 1a. There is also a gap between the first surface 221a of the outer edge 231 and the first end plate 112a. The joint 232 breaks when a load greater than a predetermined load is applied along the row direction Z (the direction in which the lithium-ion secondary batteries 1 are arranged). More specifically, as the lithium-ion secondary battery 1 gradually expands, the outer edge 231 in contact with the lithium-ion secondary battery 1a is pushed in the direction F. Furthermore, the first end plate 112a is fixed as a restraining member 110. As a result, the protrusion 230 in contact with the first end plate 112a is pushed back in the Rr direction. This causes the joint 232 to be sheared and broken. After the joint 232 breaks, the protrusion 230, which has been separated from the outer edge 231, is pushed into the gap 400 between the second surface 221b of the protrusion 230 and the wide surface 11b1 of the lithium-ion secondary battery 1a. As shown in Figure 8, the thickness of the breakable spacer 220 decreases by the amount that the protrusion 230 is pushed in. In this example, the outer edge 231 moves in the F direction and comes into contact with the first end plate 112a.

[0049] The fracture-type spacer 220 described above has a protrusion 230 that extends in the direction in which multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other, and an outer edge portion 231 that surrounds the protrusion. In addition, there is a joint portion 232 between the protrusion 230 and the outer edge portion 231. This joint portion 232 breaks when a load greater than a predetermined load is applied. As a result, the thickness of the fracture-type spacer 220 is reduced. Such a fracture-type spacer 220 has the advantage of having fewer parts because it can be made from a single component.

[0050] With respect to such a fracture-type spacer 220, the load at which the joint 232 breaks (i.e., the load at which the thickness of the fracture-type spacer 220 decreases) can typically be adjusted by changing the thickness of the joint 232 (in other words, the thickness of the part that breaks). For example, if the thickness of the joint 232 is reduced, the load required for the joint 232 to break (in other words, for the thickness of the fracture-type spacer 220 to decrease) decreases. Conversely, if the thickness of the joint 232 is increased, the load required for the joint 232 to break increases. The thickness of such a joint 232 can be appropriately set by a person skilled in the art through preliminary tests, etc. For example, by forming the fracture-type spacer 220 so that the thickness of the joint 232 is between 0.8 mm and 1.6 mm, the predetermined load can be set to 4 kN to 80 kN. Furthermore, by forming the breakable spacer 220 such that the thickness of the joint 232 is between 1.1 mm and 2.0 mm, the predetermined load can be set to 70 kN to 85 kN. More preferably, by forming the breakable spacer 220 such that the thickness of the joint 232 is between 1.5 mm and 3.0 mm, the predetermined load can be set to 75 kN to 120 kN. Such a breakable spacer 220 can be easily manufactured, for example, by press-forming a metal plate to form a protrusion.

[0051] (Example 2: Fitting type spacer 320) Other preferred examples of the spacer 120 as described above include, for example, those shown in Figures 9 to 12. In this example, the interlocking spacer 320 has a convex-side spacer 330 and a concave-side spacer 340. Figure 9 is a schematic plan view showing one preferred embodiment of the spacer 120 disclosed herein (interlocking convex-side spacer 330). In this example, the convex-side spacer 330 has a first surface 330a (front surface) and a second surface 330b which is the back surface of the first surface 330a. Figure 9 is a plan view of the convex-side spacer 330 as seen from the first surface 330a side. Figure 10 is a schematic plan view showing one preferred embodiment of the spacer 120 disclosed herein (interlocking concave-side spacer 340). In this example, the recessed spacer 340 has a first surface 340a (front surface) and a second surface 340b which is the back surface of the first surface 340a. Figure 10 is a plan view of the recessed spacer 340 as seen from the second surface 340b side. Figure 11 is a schematic longitudinal cross-sectional view of a preferred embodiment of the spacer 120 disclosed herein (fitting type spacer 320) before operation. Figure 12 is a schematic longitudinal cross-sectional view of a preferred embodiment of the spacer disclosed herein (fitting type spacer 320) after operation. Figures 11 and 12 show the constrained lithium-ion secondary battery 1a and the fitting type spacer 320 as seen from a direction perpendicular to the column direction Z (here, the width direction X). Figure 11 shows the fitting type spacer 320 (convex side spacer 330 and recessed side spacer 340) in a state where they are not yet fitted together. Figure 12 shows the fitted spacer 320 in Figure 11 with a load greater than a predetermined load applied along the column direction Z, resulting in a reduced thickness (in other words, a fitted state).

[0052] The convex-side spacer 330 is a spacer having a convex portion 332 that protrudes in the direction in which the multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other. As shown in Figures 11 and 12, in this example, the convex-side spacer 330 comprises a base portion 331 and a convex portion 332 extending from the base portion 331. The base portion 331 is a rectangular plate-shaped member. The convex portion 332 is a cylindrical projection that protrudes from the base portion 331. In addition, the tip of the convex portion 332 is provided with an overhang portion 333 that protrudes in a direction perpendicular to the direction in which the multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other. The shape of this overhang portion 333 is not particularly limited as long as it does not significantly impair the effects of the technology of this disclosure. As shown in Figures 11 and 12, in this example, the overhang portion 333 is round-headed. As a result, the recessed spacer 340 is guided along the curve of the corner of the protruding portion 333, allowing for smooth fitting.

[0053] The recessed spacer 340 is a spacer having a recess 341 that receives the protrusion 332. The recess 341 is a depression provided on the opposing surface (in this example, the second surface 340b) facing the protrusion 332 so that the protrusion 332 fits into it. In this example, the recess 341 is a cylindrical depression with an inner diameter larger than the diameter of the protruding portion 333 so that the protrusion 332 and the protruding portion 333 that protrudes outward from the side surface of the protrusion 332 fit into it. In addition, a crimping claw portion 342 is provided along the inner circumference at the entrance of the recess 341. This crimping claw portion 342 is a rib that protrudes toward the center from the inner circumferential surface 343 of the recess 341. In this example, the crimping claw portion 342 is provided continuously along the inner circumferential surface 343 of the recess 341. However, the crimping claw portion may be provided intermittently. As shown in Figures 11 and 12, the inner diameter d1 of the crimping claw portion 342 is set to be narrower than the inner diameter d2 of the inner circumferential surface 343 (the double dashed line shown in Figure 11 represents the inner circumferential surface 343 of the recess 341). The inner diameter d2 of the inner circumferential surface 343 is set to be larger than the maximum outer diameter OD of the protruding portion 333 so that the convex-side spacer 330 can fit inside. This makes it difficult for the fitted protruding portion 333 to come loose and makes it stronger against external forces such as shocks and vibrations.

[0054] The fitting movement of the aforementioned fitting-type spacer 320 will now be explained. As shown in Figure 11, in this example, the first surface 330a of the convex-side spacer 330 is positioned opposite the second surface 340b of the concave-side spacer 340 along the direction (column direction Z) in which multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other. Before the lithium-ion secondary batteries 1 expand, the protruding portion 333 of the convex-side spacer 330 is restrained in a state where it is pressed against the crimping claw portion 342 of the concave-side spacer 340. Note that in this state, the convex-side spacer 330 and the concave-side spacer 340 are not yet connected in a fitting manner. Therefore, there is a gap 400 between the convex portion 332 of the convex-side spacer 330 and the concave portion 341 of the concave-side spacer, into which the convex portion 332 can be pushed. When the lithium-ion secondary battery 1 expands and a load greater than a predetermined load is applied, the convex-side spacer 330 is pushed in along the column direction Z. As shown in Figure 12, after the lithium-ion secondary battery 1 expands, the convex-side spacer 330 and the concave-side spacer 340 are connected in a fitted manner. At this time, as the convex portion 332 is pushed into the gap of the concave portion 341, the distance between the convex-side spacer 330 and the concave-side spacer 340 becomes shorter, and the thickness of the spacer decreases.

[0055] The aforementioned interlocking spacer 320 has a protrusion 332 that extends in the direction in which multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other, a recess 341 provided on the opposing surface opposite the protrusion, and a crimping claw portion 342 formed at the entrance of the recess 341 opposite the protrusion 332. With this configuration, when a predetermined load is applied, the protrusion 332 fits into the recess 341, thereby reducing the thickness of the spacer. Once activated, such an interlocking spacer 320 can instantly reduce the distance between the protrusion 332 and the recess 341. Therefore, it has the advantage of being easily detected by a management system.

[0056] For such a fitted spacer 320, the fitting load (i.e., the load that reduces the thickness of the fitted spacer 320) can typically be adjusted by changing the difference (OD-d2) between the maximum outer diameter OD of the protruding portion 333 and the inner diameter d2 of the crimping claw portion 342 (the inner diameter of the entrance to the recess 341, i.e., the opening of the recess 341 narrowed by the crimping claw portion 342). For example, if the maximum outer diameter OD of the protruding portion 333 is reduced (and / or the inner diameter d2 of the crimping claw portion 342 is increased), the difference in the fitted portion becomes smaller, and therefore the load required for fitting decreases. Conversely, if the maximum outer diameter OD of the protruding portion 333 is increased (and / or the inner diameter d2 of the crimping claw portion 342 is reduced), the difference in the fitted portion becomes larger, and therefore the load required for fitting increases. The magnitude of such a difference in the fitted portion can be appropriately set by a person skilled in the art through preliminary tests, etc. For example, by forming the fitting spacer 320 such that the difference in the mating portion is between 0.1 mm and 0.6 mm, a predetermined load can be set to 4 kN to 30 kN. Alternatively, by forming the fitting spacer 320 such that the difference in the mating portion is between 0.15 mm and 0.8 mm, a predetermined load can be set to 6 kN to 50 kN. More preferably, by forming the fitting spacer 320 such that the difference in the mating portion is between 0.3 mm and 1 mm, a predetermined load can be set to 15 kN to 80 kN. Such a fitting spacer 320 can be easily manufactured, for example, by cutting a metal plate to form convex and concave portions.

[0057] Preferred embodiments of this disclosure have been described above based on the drawings. However, this description is not limiting, and various modifications are of course possible.

[0058] <Other Embodiments> Other embodiments using the energy storage module disclosed herein will be described below. However, this disclosure is not intended to be limited to the following descriptions.

[0059] <Energy storage module with multiple spacers> Another preferred example of the energy storage module disclosed herein is one that includes a plurality of spacers 120. Figure 13 is a schematic side view of an energy storage module 101a according to another embodiment disclosed herein. As shown in Figure 13, the spacers 120 are located at both ends of a plurality of arranged lithium-ion secondary batteries 1 (the first end 2a and the second end 2z of the stack 2). In this example, a spacer 120 is provided between the lithium-ion secondary battery 1a on the first end 2a side of the stack 2 and the first end plate 112a. Furthermore, it is also provided between the lithium-ion secondary battery 1z on the second end 2z side and the second end plate 112b. This makes it possible to reduce the thickness in the column direction Z when a load greater than a predetermined load is applied along the column direction Z. This effect makes it possible to more reliably suppress the dislodgement of electrolyte from the electrode body 20 by making the reduction of the confinement pressure greater.

[0060] A more preferred example involves operating the spacers at both ends in stages. Figure 14 is an explanatory diagram illustrating the movement of the first spacer 120a and the second spacer 120b of a power storage module 101b according to another embodiment disclosed herein. This power storage module 100 includes a first spacer 120a provided between the power storage device (here, a lithium-ion secondary battery 1a) on the first end 2a side and the first end plate 112a, and a second spacer 120b provided between the power storage device (here, a lithium-ion secondary battery 1z) on the second end 2z side and the second end plate 112b. Here, the thickness of the first spacer 120a decreases when a load greater than a predetermined load is applied along the direction in which the lithium-ion secondary batteries 1 are arranged with their wide faces 11b1 and 11b2 facing each other (here, the column direction Z). Furthermore, the second spacer 120b is configured such that its thickness decreases when a load greater than the load that reduces the thickness of the first spacer 120a is applied along the column direction Z. As shown in Figure 14, due to rapid charging and discharging, multiple energy storage devices (in this case, lithium-ion secondary batteries 1) gradually expand along the column direction Z. As a result, the first spacer 120a and the second spacer 120b are pressed together along the column direction Z. In this example, first, when a load greater than a predetermined load (e.g., 4kN to 80kN) is applied, the thickness of the first spacer 120a decreases. Next, when a load greater than the load that reduces the thickness of the first spacer 120a (e.g., 15kN to 80kN) is applied, the thickness of the second spacer 120b decreases. This makes it possible to more reliably suppress the expulsion of electrolyte from the electrode body 20. In addition, it is possible to suppress the rapid expansion of the energy storage devices.

[0061] <Pack-type energy storage module> One preferred embodiment of the energy storage module disclosed herein is, for example, a pack-type module as shown in Figure 14. Figure 15 is a schematic perspective view of the pack-case type energy storage module 102 disclosed herein. In Figure 15, the pack-case type energy storage module 102 is shown partially disassembled to show its configuration. As shown in Figure 14, a plurality of energy storage devices (in this case, lithium-ion secondary batteries 1) are arranged in a direction (in this case, the column direction Z) with their wide surfaces 11b1 and 11b2 facing each other. The pack-case type energy storage module 102 houses the plurality of lithium-ion secondary batteries 1 inside a restraining member 110 (in this example, a pack case 210).

[0062] As shown in Figure 15, the restraining member 110 may be, for example, a pack case 210. This pack case 210 has a top wall (not shown), a bottom wall 211, a first side wall 212a, a second side wall 212b, a third side wall 213a, and a fourth side wall 213b. Here, the first side wall 212a and the second side wall 212b face each other. The third side wall 213a and the fourth side wall 213b face each other. A stack 2 of multiple lithium-ion secondary batteries 1 arranged in the column direction Z is housed in the internal space of the pack case 210. Note that multiple stacks 2 (three columns in Figure 15, but not limited to this) are arranged in the width direction X perpendicular to the column direction Z. The first side wall 212a and the second side wall 212b extending along the width direction X can directly support the stack 2.

[0063] Each stack of energy storage devices (laminated 2) has a first end 2a, which is one end in the direction in which multiple lithium-ion secondary batteries 1 are arranged with their wide surfaces 11b1 and 11b2 facing each other, and a second end 2b on the opposite side of the first end 2a. Here, a spacer 120 is placed between the lithium-ion secondary battery 1a on the first end 2a side in the column direction Z of each stack 2 and the restraining member 110 (the first side wall 212a of the pack case 210). The thickness of this spacer 120 decreases when a load greater than a predetermined load is applied along the column direction Z.

[0064] In the pack-case type energy storage module 102 described above, multiple lithium-ion secondary batteries 1 (stacked 2) are supported by spacers 120 via the side walls (in this case, the first side wall 212a) of the pack case 210. With this configuration, when the lithium-ion secondary batteries 1 in the stacked 2 expand, the thickness of the spacers 120 decreases. This reduces the constraint pressure on that row.

[0065] Furthermore, this pack-case type energy storage module 102 has a so-called Cell-to-Pack structure in which multiple energy storage devices are housed together. With such a Cell-to-Pack structure, the number of restraining members can be reduced, thereby improving the volumetric energy efficiency of the module. Alternatively, a Cell-Module-Pack structure in which the energy storage module 100 containing the aforementioned multiple energy storage devices is housed inside the pack case 210 may also be used.

[0066] <Use of energy storage modules> The number of energy storage devices included in the energy storage module disclosed herein is not particularly limited. The number of energy storage devices may be appropriately determined depending on the intended use of the energy storage module. For example, the number of energy storage devices may be 10 or more, 20 or more, or 30 or more.

[0067] The energy storage module disclosed herein can be used for various applications. However, in the case of high capacity modules (for example, with an energy density of 500 Wh / L or more per cell), the case tends to bulge due to rapid charge-discharge cycles, making the technology disclosed herein particularly suitable. Applications requiring such an energy storage module include, for example, power sources (drive power supplies) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0068] The technologies disclosed herein may be omitted or combined as appropriate, unless no particular problems arise. Furthermore, this specification includes the disclosures described in the following sections.

[0069] Item 1: An energy storage module comprising a plurality of energy storage devices, a restraining member, and a spacer, wherein the plurality of energy storage devices have a pair of opposing wide surfaces and are arranged with the wide surfaces facing each other, the restraining member is configured to restrain the plurality of energy storage devices in the direction in which the plurality of energy storage devices are arranged with the wide surfaces facing each other, and the spacer is positioned between the energy storage device located at the first end of the plurality of devices in the direction in which they are arranged and the restraining member, and the thickness decreases when a load greater than a predetermined load is applied along the direction in which they are arranged.

[0070] Item 2: The energy storage module according to Item 1, wherein the energy storage device comprises an electrode body and a rectangular case housing the electrode body, the restraining member comprises a first end plate positioned at the first end of the plurality of devices in the direction in which they are arranged, a second end plate positioned at the second end on the opposite side from the first end, and a side bar spanning between the first end plate and the second end plate, and the spacer is provided between the first end plate and the wide surface of the energy storage device on the first end.

[0071] Item 3: The energy storage module described in Item 1 or Item 2, wherein the predetermined load is between 4kN and 80kN.

[0072] Item 4: The energy storage module according to any one of items 1 to 3, wherein the spacer is rectangular and has a protrusion projecting in the direction of the arrangement, an outer edge surrounding the protrusion, and a joint connecting the protrusion and the outer edge, the joint being formed to be thinner than the thickness of the protrusion or the outer edge, and the thickness decreases when a load greater than a predetermined load is applied along the direction of the arrangement by the joint breaking.

[0073] Item 5: The energy storage module according to any one of items 1 to 3, wherein the spacer has a convex portion protruding in the direction of alignment, a recess provided on an opposing surface facing the convex portion, and a crimping claw portion formed at the entrance of the recess facing the convex portion, the convex portion being positioned in contact with the crimping claw portion such that a gap is formed between it and the recess, and the thickness is reduced when a load greater than a predetermined load is applied along the direction of alignment by the convex portion and the recess fitting together.

[0074] Item 6: The energy storage module according to any one of items 1 to 5, wherein the spacer is also provided between the energy storage device on the second end side and the second end plate. [Explanation of Symbols]

[0075] 1. Lithium-ion rechargeable battery 1a Lithium-ion secondary battery at the first end 1z Lithium-ion secondary battery at the second end 2 Laminate 2a 1st end 2z 2nd end 10 cases 11 Main unit 11a Bottom 11b1, 11b2 Wide surface 11c1, 11c2 narrow side 12 Sealing plate 13 Safety valve 14 Positive external terminal 15 Negative external terminal 16 Positive internal terminal 17 Negative internal terminal 18 Gaskets 19 Insulators 20 Electrode body 21 flat plane 30 positive electrode 31 Positive electrode current collector foil 31a Portion where positive electrode active material layer is not formed 31b Positive electrode protective layer 31c positive electrode tab 32 Positive electrode active material layer 40 negative electrode 41 Negative electrode current collector foil 41a Part where negative electrode active material layer is not formed 41c Negative Electrode Tab 42 Negative electrode active material layer 50 Separators 100 Energy Storage Modules 101a, 101b Energy Storage Modules 102 Energy Storage Module 110 Restraining member 111 Bottom Plate 112a First end plate 112b Second End Plate 113 Sidebar 114 Bis 120 Spacer 120a First Spacer 120b Second Spacer 210 cabinets 211 Bottom wall 212a 1st side wall 212b 2nd side wall 213a 3rd side wall 213b 4th side wall 220 Break-type spacer 221a 1st page 221b 2nd page 230 protrusion 231 Outer edge 232 Joint 320 Fitting type spacer 330 Convex side spacer 330a Page 1 330b 2nd side 331 Base 332 Convex part 333 Protruding section 340 Recessed side spacer 340a 1st page 340b 2nd side 341 Recess 342 Crimping claw portion 343 Inner surface 400 gap OD (Outer Diameter of Overhang) d1 Inner diameter of the crimping claw portion d2 Inner diameter of the side surface

Claims

1. Multiple energy storage devices, Restricting member and Spacer and, Equipped with, The plurality of energy storage devices each have a pair of opposing wide surfaces, and the wide surfaces are arranged facing each other. The restraining member is configured to restrain the plurality of energy storage devices in the direction in which the plurality of energy storage devices are arranged with their wide surfaces facing each other. The previous spacer is Displaced between the energy storage device and the restraining member, which are located at the first end of the arrangement of the plurality of devices, A battery storage module whose thickness decreases when a load greater than a predetermined load is applied along the aforementioned arranged direction.

2. The aforementioned energy storage device is It comprises an electrode body and a rectangular case that houses the electrode body, The restraining member is A first end plate is positioned at the first end of the aforementioned plurality of devices in the direction in which they are arranged, A second end plate is positioned on the second end side, which is on the opposite side from the first end side, A side bar is stretched between the first end plate and the second end plate, It has, The previous spacer is The energy storage module according to claim 1, provided between the first end plate and the wide surface of the energy storage device on the first end side.

3. The energy storage module according to claim 2, wherein the predetermined load is 4 kN or more and 80 kN or less.

4. The previous spacer is It is rectangular, The convex portions that protrude in the aforementioned aligned directions, The outer edge portion surrounding the aforementioned protrusion, A joint connecting the aforementioned protrusion and the aforementioned outer edge, It has, The joint portion is formed to be thinner than the thickness of the protrusion or the outer edge portion. The energy storage module according to claim 2, wherein the thickness decreases when a load greater than a predetermined load is applied along the aforementioned aligned direction, by the fracture of the joint.

5. The previous spacer is The convex portions that protrude in the aforementioned aligned directions, A recess is provided on the opposing surface opposite to the convex portion, A crimping claw portion formed at the entrance of the recess opposite to the convex portion, It has, The convex portion is positioned in contact with the crimping claw portion such that a gap is formed between it and the concave portion. The energy storage module according to claim 2, wherein when a load greater than a predetermined load is applied along the aforementioned arranged direction, the protrusions and recesses fit together, thereby reducing the thickness.

6. The energy storage module according to any one of claims 2 to 5, wherein the spacer is also provided between the energy storage device on the second end side and the second end plate.

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