Power storage module

Abstract

To provide a power storage module capable of suppressing heat transfer to an adjacent power storage device.SOLUTION: A power storage module disclosed herein includes a first power storage device 110 and a second power storage device 120 arranged along an arrangement direction X, and a spacer 200. The spacer 200 has a pair of end areas A1 and A3 and a central area A2 in the first direction Z orthogonal to the array direction X. The pair of end areas A1, A3 and central area A2 contain resins different from each other, and are configured such that the resins contained in central area A2 melt earlier than the resins contained in the pair of end areas A1, A3 when a temperature of first power storage devices 110 increases.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an electricity storage module. [Background technology]

[0002] Conventionally, power storage modules in which a plurality of power storage devices are electrically connected have been widely used as power sources for driving vehicles, etc. In a power storage module, if the temperature of one power storage device rises due to, for example, an internal short circuit or overcharging, there is a risk that the heat will be transferred to adjacent power storage devices. Therefore, there is a need to suppress the heat transfer to adjacent power storage devices. Patent Documents 1 to 4 are examples of related art documents in this regard.

[0003] For example, Patent Document 1 discloses an electricity storage module including a plurality of electricity storage devices arranged along an arrangement direction, spacers arranged between the plurality of electricity storage devices, and a restraining member that restrains the plurality of electricity storage devices and the spacers in the arrangement direction. Patent Document 1 describes that the spacers have a mesh-like fire spread prevention layer (air layer) that is configured to suppress heat transfer by air existing in the gaps in the mesh. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018-207608 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-004294 [Patent Document 3] International Publication No. 2021-171782 [Patent Document 4] Special Publication No. 2023-524706 Summary of the Invention [Problem to be solved by the invention]

[0005] The above technology has a problem in that it is difficult to secure an air gap between the power storage devices when the power storage devices and the spacer are constrained in the arrangement direction, for example. Therefore, a new configuration has been desired that can suppress heat transfer to adjacent power storage devices when the temperature of one power storage device rises.

[0006] The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a novel electricity storage module that can suppress heat transfer to adjacent electricity storage devices. [Means for solving the problem]

[0007] The present invention discloses an energy storage module including a first energy storage device and a second energy storage device arranged along an arrangement direction, and a spacer arranged between the first energy storage device and the second energy storage device. The spacer has, in a first direction perpendicular to the arrangement direction, a pair of end regions and a central region located between the pair of end regions. The pair of end regions and the central region contain different resins, and when the temperature of the first energy storage device increases, the resin contained in the central region melts faster than the resin contained in the pair of end regions.

[0008] According to the present invention, when the temperature of the first power storage device rises due to overcharging or the like, the resin melts in the central region of the spacer, creating a partial gap (air layer). At this time, the resin remains unmelted in the pair of end regions of the spacer. This allows an air layer to be secured between the adjacent second power storage devices while maintaining the distance between them. Therefore, air insulation can effectively suppress heat transfer to the adjacent second power storage devices. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view schematically illustrating an electricity storage module according to one embodiment. [Figure 2] FIG. 2 is a perspective view schematically showing the electricity storage device of FIG. [Figure 3] FIG. 3 is a schematic vertical cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a perspective view that schematically shows an electrode assembly attached to a sealing plate. [Figure 5] FIG. 5 is a perspective view schematically showing one electrode body of FIG. [Figure 6] FIG. 6 is a schematic diagram showing the configuration of the electrode body. [Figure 7] FIG. 7 is a perspective view schematically showing the spacer of FIG. [Figure 8] FIG. 8(A) is a side view that schematically shows a normal state, and FIG. 8(B) is a side view that schematically shows a state when the temperature rises. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the energy storage module disclosed herein will be described below with reference to the drawings as appropriate. Matters other than those specifically mentioned in this specification that are necessary for implementing the present invention (for example, the general configuration and manufacturing process of an energy storage module or energy storage device that do not characterize the present invention) can be understood as design matters for those skilled in the art based on prior art in the relevant field. The energy storage module disclosed herein can be implemented based on the contents disclosed in this specification and common technical knowledge in the relevant field.

[0011] In the following drawings, the same reference numerals are used to designate components and parts that perform the same function, and redundant explanations may be omitted or simplified. In addition, in this specification, the expression "A to B" indicating a range means not less than A and not more than B, and also encompasses the meanings of "preferably larger than A" and "preferably smaller than B."

[0012] 1 is a perspective view schematically illustrating an energy storage module 500 according to one embodiment. The energy storage module 500 includes a plurality of energy storage devices 100 arranged along a predetermined arrangement direction X, and a spacer 200 arranged between adjacent energy storage devices 100 in the arrangement direction X. Here, the energy storage module 500 further includes a restraining mechanism 300 that restrains the plurality of energy storage devices 100 and the spacer 200 in the arrangement direction X. However, the restraining mechanism 300 is not essential and may be omitted in other embodiments.

[0013] In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the symbols X, Y, and Z in the drawings represent the thickness direction, width direction perpendicular to the thickness direction, and height direction perpendicular to the thickness direction and width direction, respectively, of the energy storage device 100. The thickness direction X is also the arrangement direction of the energy storage devices 100. However, these directions are merely provided for the convenience of description and do not limit the installation form of the energy storage module 500 in any way.

[0014] The restraining mechanism 300 is a mechanism that restrains the plurality of power storage devices 100 and the spacers 200 in the arrangement direction X. The restraining mechanism 300 is configured to apply a specified restraining pressure to the plurality of power storage devices 100 and the spacers 200 in the arrangement direction X. Here, the restraining mechanism 300 includes a pair of end plates 310, a pair of side plates 320, and a plurality of screws 330. The pair of end plates 310 and the pair of side plates 320 can also be understood as a box that houses the plurality of power storage devices 100. The pair of end plates 310 and the pair of side plates 320 are preferably made of metal. However, a portion of the pair of end plates 310 and / or the pair of side plates 320 may be made of resin.

[0015] The pair of end plates 310 are arranged at both ends of the power storage module 500 in the arrangement direction X. The pair of end plates 310 sandwich the power storage devices 100 and the spacers 200 in the arrangement direction X.

[0016] The pair of side plates 320 bridge the pair of end plates 310. The pair of side plates 320 are fixed to the end plates 310 with a plurality of screws 330 so that the restraining load is, for example, approximately 10 to 15 kN. As a result, a restraining load is applied to the plurality of power storage devices 100 and the spacers 200 in the arrangement direction X, and the power storage module 500 is held integrally. However, the configuration of the restraining mechanism is not limited to this. The restraining mechanism 300 may include, for example, a plurality of restraining bands or bind bars instead of the side plates 320. In another embodiment, the power storage devices 100 may be arranged in a box without using the restraining mechanism 300.

[0017] The power storage device 100 is a device that can be repeatedly charged and discharged. In this specification, the term "power storage device" is a concept that encompasses secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries, as well as capacitors that utilize chemical reactions, such as lithium-ion capacitors and pseudo-capacitor capacitors. The shape, size, number, arrangement, etc. of the multiple power storage devices 100 that make up the power storage module 500 are not limited to the embodiment disclosed in FIG. 1 and can be changed as appropriate.

[0018] In FIG. 1 , the plurality of power storage devices 100 are arranged between a pair of end plates 310 along an arrangement direction X (a thickness direction X of the power storage devices 100). A spacer 200 is disposed between adjacent power storage devices 100 in the arrangement direction X. That is, the power storage devices 100 and the spacers 200 are arranged alternately in the arrangement direction X. However, in other embodiments, another member (for example, a conventionally known heat insulating material) may be disposed between the power storage devices 100 and the spacers 200. As will be described in detail later, the plurality of power storage devices 100 are connected in series by bus bars here. However, the method of connecting the plurality of power storage devices 100 is not limited to series and may be, for example, parallel, multi-series, multi-parallel, or the like.

[0019] Fig. 2 is a perspective view of the electricity storage device 100. As can be seen from Figs. 1 and 2, the multiple electricity storage devices 100 are all flat and rectangular, and have the same shape here. The multiple electricity storage devices 100 are arranged so that their long side surfaces 12b, which will be described later, face each other. The multiple electricity storage devices 100 are arranged so that their long side surfaces 12b are parallel to each other.

[0020] Although not particularly limited, the battery capacity of the power storage device 100 is preferably 50 Ah or more, more preferably 100 Ah or more, and even more preferably, for example, 150 Ah or more, or 200 Ah or more. If the battery capacity is greater than a predetermined value, the amount of heat generated by the power storage device 100 is likely to increase when an internal short circuit or the like occurs. Therefore, it is particularly effective to apply the technology disclosed herein. From the viewpoint of utilizing the technology disclosed herein at a high level, the battery capacity of the power storage device 100 is preferably 500 Ah or less.

[0021] Fig. 3 is a schematic longitudinal cross-sectional view taken along line III-III in Fig. 2. As shown in Fig. 3, the electricity storage device 100 includes a battery case 10, an electrode assembly 20, a positive electrode terminal 30, a negative electrode terminal 40, and an electrolyte (not shown). The electricity storage device 100 is typically a non-aqueous electrolyte secondary battery, and is a lithium ion secondary battery in this case. When the electricity storage device 100 is a lithium ion secondary battery, it is particularly effective to apply the techniques disclosed herein.

[0022] The battery case 10 is a housing that houses the electrode assembly 20 and the electrolyte. As shown in FIG. 2, the battery case 10 has a flat, bottomed, rectangular parallelepiped (rectangular) outer shape. The material of the battery case 10 may be the same as that conventionally used, and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, aluminum, an aluminum alloy, iron, an iron alloy, or the like. As shown in FIG. 3, the battery case 10 includes an exterior body 12 having an opening 12h, and a sealing plate (lid) 14 that seals the opening 12h.

[0023] As shown in Fig. 2, the exterior body 12 has a substantially rectangular bottom surface 12a having long and short sides, a pair of long side surfaces 12b extending from the long side of the bottom surface 12a and facing each other, and a pair of short side surfaces 12c extending from the short side of the bottom surface 12a and facing each other. The bottom surface 12a faces the opening 12h (see Fig. 3). The long side surfaces 12b are flat. The long side surfaces 12b are surfaces facing the spacer 200. In this example, the long side surfaces 12b are in direct contact with the spacer 200. However, in other embodiments, the long side surfaces 12b may face the spacer 200 via another member.

[0024] In a plan view, the area of ​​the long side surface 12b is larger than the area of ​​the short side surface 12c. Although not particularly limited, in the case of a high-capacity type used in a vehicle, the area of ​​the long side surface 12b is approximately 10,000 mm 2 It is better to have more than 15,000 mm 2 More than 20,000mm is preferable. 2 More than 25,000mm is more preferable. 2 More preferably, 30,000 mm 2 The above is particularly preferable. When the area of ​​the long side surface 12b is large like this, the center of the long side surface 12b is particularly likely to become hot when an internal short circuit or the like occurs. Therefore, applying the technology disclosed herein is particularly effective. Furthermore, from the viewpoint of achieving the effects of the technology disclosed herein at a high level, the area of ​​the long side surface 12b is set to approximately 150,000 mm 2 The following is preferred:

[0025] The sealing plate 14 is a plate-like member extending along the XY plane in FIG. 2. As shown in FIG. 3, the sealing plate 14 is attached to the exterior body 12 so as to close the opening 12h. The sealing plate 14 faces the bottom surface 12a of the exterior body 12. The sealing plate 14 is substantially rectangular. The battery case 10 is integrated by joining (preferably welding) the sealing plate 14 to the periphery of the opening 12h of the exterior body 12. The battery case 10 is hermetically sealed (sealed).

[0026] As shown in Fig. 3, the sealing plate 14 is provided with a liquid inlet 15, a drain valve 17, and two terminal outlet holes 18 and 19. The liquid inlet 15 is for injecting electrolyte into the battery case 10 after the sealing plate 14 is assembled to the exterior body 12. The liquid inlet 15 is sealed with a sealing member 16. The drain valve 17 is configured to break when the pressure inside the battery case 10 reaches or exceeds a predetermined value, thereby discharging gas inside the battery case 10 to the outside. The terminal outlet holes 18 and 19 penetrate the sealing plate 14 in the height direction Z.

[0027] The positive electrode terminal 30 is disposed at one end of the sealing plate 14 in the width direction Y (the left end in FIGS. 2 and 3). The negative electrode terminal 40 is disposed at the other end of the sealing plate 14 in the width direction Y (the right end in FIGS. 2 and 3). As shown in FIG. 3, the positive electrode terminal 30 and the negative electrode terminal 40 extend from the inside to the outside of the sealing plate 14 through the terminal lead-out holes 18 and 19, respectively. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are crimped to the peripheral portion of the sealing plate 14 surrounding the terminal lead-out holes 18 and 19 by crimping. Crimped portions 30c and 40c are formed at the ends of the positive electrode terminal 30 and the negative electrode terminal 40 on the exterior body 12 side (the lower end in FIG. 3). In this way, the positive electrode terminal 30 and the negative electrode terminal 40 are fixed to the sealing plate 14.

[0028] As shown in Fig. 3, the positive electrode terminal 30 is electrically connected to the positive electrode tab group 23 of the electrode assembly 20 via a positive electrode current collecting member 50 inside the exterior housing 12. The positive electrode terminal 30 is insulated from the sealing plate 14 by an internal insulating member 80 and a gasket 90. The negative electrode terminal 40 is electrically connected to the negative electrode tab group 25 of the electrode assembly 20 via a negative electrode current collecting member 60 inside the exterior housing 12. The negative electrode terminal 40 is insulated from the sealing plate 14 by the internal insulating member 80 and the gasket 90.

[0029] As shown in FIGS. 2 and 3 , a plate-shaped positive electrode external conductive member 32 and a plate-shaped negative electrode external conductive member 42 are attached to the outer surface of the sealing plate 14. The positive electrode external conductive member 32 is electrically connected to the positive electrode terminal 30. The negative electrode external conductive member 42 is electrically connected to the negative electrode terminal 40. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by an external insulating member 92. As shown in FIG. 1 , the positive electrode external conductive member 32 and the negative electrode external conductive member 42 are provided with bus bars that electrically connect a plurality of electricity storage devices 100 to each other. Here, of two adjacent electricity storage devices 100, the positive electrode external conductive member 32 of one electricity storage device 100 is electrically connected to the negative electrode external conductive member 42 of the other electricity storage device 100 by the bus bar. This electrically connects the electricity storage modules 500 in series.

[0030] FIG. 4 is a perspective view that schematically shows an electrode assembly 20 attached to a sealing plate 14. The electrode assembly 20 here has a plurality of electrode bodies. The electrode assembly 20 here has three electrode bodies 20a, 20b, and 20c. If a plurality of electrode bodies are arranged inside one battery case 10, the amount of heat generated by the electricity storage device 100 is likely to increase in the event of an internal short circuit or the like. Therefore, applying the technology disclosed herein is particularly effective. However, the number of electrode bodies arranged inside one exterior body 12 is not particularly limited, and may be one, two, or four or more.

[0031] The electrode assemblies 20a, 20b, and 20c are arranged in the thickness direction X. The electrode assemblies 20a, 20b, and 20c are electrically connected in parallel. The electrode assemblies 20a, 20b, and 20c each have a flat outer shape. The electrode assemblies 20a, 20b, and 20c are each wound electrode assemblies. However, in other embodiments, the electrode assemblies 20a, 20b, and 20c may each be a stacked electrode assembly formed by stacking multiple square-shaped (typically rectangular) positive electrodes and multiple square-shaped (typically rectangular) negative electrodes in an insulated state.

[0032] FIG. 5 is a perspective view schematically illustrating the electrode body 20b. The configuration of the electrode body 20b may be the same as that of a conventional electrode body and is not particularly limited. Note that the electrode body 20b will be described in detail below as an example, but the electrode bodies 20a and 20c may also have a similar configuration. The electrode body 20b has a pair of curved portions (R portions) 20r and a flat portion 20f connecting the pair of curved portions 20r. The first curved portion 20r (upper side in FIG. 5) faces the sealing plate 14, and the second curved portion 20r (lower side in FIG. 5) faces the bottom surface 12a of the exterior body 12. The flat portion 20f faces the long side surface 12b of the exterior body 12. The flat portions 20f of the electrode bodies 20a, 20b, and 20c adjacent to each other in the thickness direction X face each other.

[0033] FIG. 6 is a schematic diagram showing the configuration of the electrode assembly 20b. As shown in FIG. 6, the electrode assembly 20b has a positive electrode 22, a negative electrode 24, and a separator 26. In this example, the electrode assembly 20b is configured by stacking a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 with a strip-shaped separator 26 interposed therebetween and winding them around a winding axis WL. Here, the winding axis WL direction is oriented along the width direction Y. The electrode assembly 20b is disposed inside the battery case 10 with the winding axis WL oriented perpendicular to the arrangement direction X and the height direction Z. However, in other embodiments, the winding axis WL direction may be oriented along the height direction Z, and the electrode assembly 20b may be disposed inside the battery case 10 with the winding axis WL oriented perpendicular to the arrangement direction X and the width direction Y.

[0034] The configuration of the positive electrode 22 may be the same as that of a conventional positive electrode. As shown in FIG. 6, the positive electrode 22 includes a positive electrode current collector 22c, a positive electrode active material layer 22a, and a positive electrode protective layer 22p, which are fixed to at least one surface of the positive electrode current collector 22c. However, the positive electrode protective layer 22p is not essential and may be omitted in other embodiments. The positive electrode current collector 22c is strip-shaped. The positive electrode current collector 22c is preferably made of metal, and more preferably made of metal foil. Here, the positive electrode current collector 22c is aluminum foil.

[0035] A plurality of positive electrode tabs 22t are provided at one end in the width direction Y of the positive electrode current collector 22c (the left end in FIG. 6). Each of the plurality of positive electrode tabs 22t is convex and protrudes toward one side in the width direction Y (the left side in FIG. 6). The plurality of positive electrode tabs 22t protrude in the width direction Y beyond the separator 26. In this example, the positive electrode tab 22t is part of the positive electrode current collector 22c and is made of metal foil (aluminum foil). As shown in FIGS. 3 to 5, the plurality of positive electrode tabs 22t are stacked at one end in the width direction Y to form a positive electrode tab group 23. The positive electrode tab group 23 is electrically connected to the positive electrode terminal 30 via a positive electrode current collecting member 50.

[0036] As shown in FIG. 6, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction of the positive electrode current collector 22c. The positive electrode active material layer 22a contains a positive electrode active material that can reversibly store and release charge carriers. Examples of the positive electrode active material include lithium transition metal composite oxides. The positive electrode active material layer 22a may contain optional components other than the positive electrode active material, such as a binder, a conductive material, and various additives.

[0037] As shown in Fig. 6, the positive electrode protective layer 22p is provided at the boundary between the positive electrode current collector 22c and the positive electrode active material layer 22a in the width direction Y. The positive electrode protective layer 22p is provided in a strip shape along the positive electrode active material layer 22a. The positive electrode protective layer 22p contains an inorganic filler (e.g., alumina). The positive electrode protective layer 22p may contain optional components other than the inorganic filler, such as a conductive material, a binder, and various additives.

[0038] The configuration of the negative electrode 24 may be the same as that of a conventional negative electrode. As shown in FIG. 6, the negative electrode 24 here has a negative electrode current collector 24c and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector 24c. The negative electrode current collector 24c is strip-shaped. The negative electrode current collector 24c is preferably made of metal, more preferably metal foil. Here, the negative electrode current collector 24c is copper foil.

[0039] A plurality of negative electrode tabs 24t are provided at one end in the width direction Y of the negative electrode current collector 24c (the right end in FIG. 6). The plurality of negative electrode tabs 24t protrude toward one side in the width direction Y (the right side in FIG. 6). Each of the plurality of negative electrode tabs 24t has a convex shape and protrudes further in the width direction Y than the separator 26. Here, the negative electrode tab 24t is part of the negative electrode current collector 24c and is made of metal foil (copper foil). As shown in FIGS. 3 to 5, the plurality of negative electrode tabs 24t are stacked at one end in the width direction Y to form a negative electrode tab group 25. The negative electrode tab group 25 is electrically connected to the negative electrode terminal 40 via a negative electrode current collecting member 60.

[0040] As shown in Fig. 6, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction of the negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material that can reversibly store and release charge carriers. Examples of the negative electrode active material include carbon materials such as graphite. The negative electrode active material layer 24a may contain optional components other than the negative electrode active material, such as a binder, a thickener, a dispersant, and various additives.

[0041] The length Ln of the negative electrode active material layer 24a in the width direction Y (average length in the direction of the winding axis WL) is preferably equal to or longer than the length Lp of the positive electrode active material layer 22a in the width direction Y (average length in the direction of the winding axis WL). In some embodiments, the length Ln of the negative electrode active material layer 24a is preferably 15 cm or more, and more preferably 20 cm or more. If the length Ln of the negative electrode active material layer 24a is equal to or greater than a predetermined value, the amount of heat generated by the power storage device 100 is likely to increase in the event of an internal short circuit or the like, and the central portion in the width direction Y is likely to become particularly hot. Therefore, applying the technology disclosed herein is particularly effective. The length Ln of the negative electrode active material layer 24a may be approximately 45 cm or less, for example, 40 cm or less.

[0042] In some embodiments, the length Ln of the negative electrode active material layer 24a is preferably longer than the height H of the electrode bodies 20a, 20b, and 20c. That is, the ratio (Ln / H) of the length Ln of the negative electrode active material layer 24a to the height H of the electrode bodies 20a, 20b, and 20c is preferably greater than 1. This allows for a more improved volumetric energy density. Furthermore, since a high volumetric energy density increases the amount of heat generated by the electricity storage device 100, applying the technology disclosed herein is particularly effective. The ratio (Ln / H) is more preferably 2 or greater, and even more preferably 2.5 or greater.

[0043] The separator 26 is disposed between the positive electrode 22 and the negative electrode 24 and serves to insulate the positive electrode 22 from the negative electrode 24. The separator 26 may have a conventional configuration. The length Ls of the separator 26 in the width direction Y (average length in the direction of the winding axis WL) is preferably equal to or longer than the length Ln of the negative electrode active material layer 24a. The separator 26 is preferably a porous sheet (microporous membrane) made of a resin such as a polyolefin resin, such as polyethylene (PE) or polypropylene (PP). The separator 26 may have a functional layer (e.g., an adhesive layer or a heat-resistant layer) on the surface of the porous sheet.

[0044] The electrolyte solution may be the same as conventional ones and is not particularly limited. The electrolyte solution is typically a non-aqueous electrolyte solution containing a non-aqueous solvent and a supporting salt (electrolyte salt). Examples of non-aqueous solvents that can be used include carbonates, esters, ethers, nitriles, sulfones, and lactones. These can be used alone or in combination of two or more. It is preferable to include carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of electrolyte salts that can be used include fluorine-containing lithium salts such as lithium hexafluorophosphate (LiPF6) and lithium tetrafluoroborate (LiBF4). The electrolyte solution may further contain additives as needed.

[0045] The spacers 200 are members for spacing the plurality of power storage devices 100 apart. As shown in FIG. 1 , the spacers 200 are disposed between the plurality of power storage devices 100 in the arrangement direction X. However, the spacers 200 only need to be disposed between at least two power storage devices 100 adjacent to each other in the arrangement direction X, and do not necessarily need to be disposed between all of the power storage devices 100. The spacers 200 are preferably disposed between 50% or more, more preferably 80% or more of the power storage devices 100. The spacers 200 may be separate from the power storage devices 100, or may be fixed to and integrated with the power storage devices 100. The spacers 200 may be sandwiched between two opposing power storage devices 100, or may be attached to the power storage devices 100 with adhesive, tape, or the like. The shape, size, arrangement, and the like of the spacers 200 can be determined appropriately depending on the shape, size, capacity, and the like of the power storage devices 100.

[0046] FIG. 7 is a perspective view schematically illustrating the spacer 200. As shown in FIG. 7, the spacer 200 is sheet-shaped and has a substantially uniform thickness T. Although not particularly limited, the thickness T (length in the arrangement direction X) of the spacer 200 is preferably 1 to 10 mm, more preferably 1 to 8 mm, and even more preferably 3 to 5 mm, before being assembled to the power storage module 500 and compressed by the restraint mechanism 300. The thickness T of the spacer 200 is preferably 0.5 to 9 mm, more preferably 1 to 7 mm, and even more preferably 3 to 5 mm, before being assembled to the power storage module 500 and compressed by the restraint mechanism 300. This ensures gaps between the multiple power storage devices 100 under normal conditions, thereby improving thermal insulation. Furthermore, when the temperature of one power storage device 100 rises, it becomes easier to ensure an air layer between the adjacent power storage devices 100, which makes it easier to suppress thermal conductivity to the adjacent power storage devices 100.

[0047] The spacer 200 has a pair of opposing surfaces 210 that are perpendicular to the arrangement direction X and extend along the YZ plane. Each of the pair of opposing surfaces 210 faces the power storage device 100 (specifically, the long side surface 12b). Here, the opposing surfaces 210 of the spacer 200 are substantially rectangular in plan view. The opposing surfaces 210 are arranged such that their long sides extend along the width direction Y and their short sides extend along the height direction Z. Although not particularly limited, the overall height Ha of the opposing surfaces 210 is preferably equal to or greater than the height H of the electrode bodies 20a, 20b, and 20c. The length La of the opposing surfaces 210 in the width direction Y is preferably approximately the same as (approximately ±1 cm) the length Ln of the negative electrode active material layer 24a. The length La of the opposing surfaces 210 may be shorter than the length Ln of the negative electrode active material layer 24a. The ratio of the area of ​​the opposing surface 210 to the area of ​​the long side surface 12b of the electricity storage device 100 is preferably approximately 50% or more, more preferably 60% or more, even more preferably 70% or more, still more preferably 75% or more, and particularly preferably 80% or more.

[0048] In some embodiments, the spacer 200 is preferably insulating. In this specification, "insulating" means that the volume resistivity measured in accordance with JIS K6911:2006 is 1.0×10 10 The volume resistivity of the spacer 200 is 1.0×10 12 Ω·cm or more is preferable.

[0049] 7, the spacer 200 has, in the height direction Z, a pair of end regions A1, A3 and a central region A2 located between the pair of end regions A1, A3. The height direction Z is an example of a "first direction perpendicular to the arrangement direction." However, in other embodiments, the "first direction perpendicular to the arrangement direction" may be the width direction Y. The spacer 200 may have, in the width direction Y, a pair of end regions (left and right end regions) and a width central region located between the pair of left and right end regions.

[0050] In this embodiment, the spacer 200 is composed of three regions. However, in other embodiments, the spacer 200 may further include other regions (fourth and fifth regions), for example, between the first end region A1 and the central region A2, or between the second end region A3 and the central region A2. Here, each region of the spacer 200 has a rectangular parallelepiped outer shape.

[0051] In this embodiment, the first end region A1 is a region (lower region) provided in a strip shape at the end (lower end) of the spacer 200 on the bottom surface 12a side. The first end region A1 is preferably a region including the lower end of the spacer 200 in the height direction Z. The first end region A1 is preferably provided so as to face the first (lower) curved portion 20r of the electrode bodies 20a, 20b, and 20c. The second end region A3 is a region (upper region) provided in a strip shape at the end (upper end) of the spacer 200 on the sealing plate 14 side. The second end region A3 is preferably a region including the upper end of the spacer 200 in the height direction Z. The second end region A3 is preferably provided so as to face the second (upper) curved portion 20r of the electrode bodies 20a, 20b, and 20c. The central region A2 is a region provided in a strip shape between the pair of end regions A1 and A3 of the spacer 200 in the height direction Z. The central region A2 is preferably a region including the center of the height direction Z (first direction) of the spacer 200. The central region A2 is preferably provided so as to face the center of the height direction Z (first direction) of the flat portions 20f of the electrode bodies 20a, 20b, and 20c.

[0052] Each region of the spacer 200 contains resin. Preferably, each region of the spacer 200 is mainly made of resin (having the highest proportion of resin by mass). Each region of the spacer 200 may be made of resin. In other words, 99% or more by mass of the entire spacer 200 may be made of resin. Each region of the spacer 200 may contain, for example, a filler such as ceramic or various additive components at a lower proportion than the resin.

[0053] In the technology disclosed herein, the pair of end regions A1, A3 and the central region A2 of the spacer 200 contain different resins. When the temperature of one power storage device 100 (first power storage device) rises, the resin contained in the central region A2 of the spacer 200 melts faster than the resin contained in the pair of end regions A1, A3. That is, in the technology disclosed herein, the central region A2 contains a resin with a relatively low melting point (hereinafter also referred to as a "low-melting-point resin"), and the pair of end regions A1, A3 contain a resin with a relatively high melting point or softening point (hereinafter also referred to as a "high-melting-point resin"). With this configuration, when the temperature of one power storage device 100 rises due to overcharging or the like, heat transfer to an adjacent power storage device 100 can be suitably suppressed. This will be described in detail below.

[0054] FIG. 8(A) is a side view schematically showing one spacer 200 and two electricity storage devices 100 (a first electricity storage device 110 and a second electricity storage device 120) in contact with the spacer 200 in a normal state. In the arrangement direction X, the spacer 200 is interposed between the first electricity storage device 110 and the second electricity storage device 120. In a normal state, that is, when the temperature of the first electricity storage device 110 is not rising (when the temperature is within a normal temperature range), the spacer 200 has a sheet-like outer shape as shown in FIG. 7. As shown in FIG. 8(A), a pair of opposing surfaces 210 of the spacer 200 are in contact with the opposing first electricity storage device 110 and second electricity storage device 120 over substantially the entire length in the height direction Z (first direction). A gap of a thickness T of the spacer 200 is secured between the first electricity storage device 110 and the second electricity storage device 120. As a result, the first power storage device 110 and the second power storage device 120 are spaced apart from each other.

[0055] On the other hand, when the temperature of the first power storage device 110 rises due to overcharging or the like, the low-melting-point resin melts in the central region A2 of the spacer 200, as shown in FIG. 8(B). This creates a partial void (air layer) in the middle of the spacer 200 in the height direction Z (first direction). At this time, the high-melting-point resin remains without melting or softening in the pair of end regions A1, A3 of the spacer 200. This ensures an air layer while maintaining the distance of thickness T between the adjacent second power storage device 120 (the same thickness as the spacer 200). Therefore, heat transfer to the adjacent second power storage device 120 can be suitably suppressed by air insulation. More suitably, heat is discharged from the end of this air layer in the width direction Y, thereby mitigating the temperature rise of the first power storage device 110.

[0056] The melting point or softening point of the resin contained in each region of the spacer 200 can be measured by a general differential scanning calorimetry (DSC).

[0057] The resin (low-melting-point resin) contained in the central region A2 has a melting point and is therefore a crystalline resin. From the viewpoint of achieving the effects of the technology disclosed herein at a higher level, the melting point of the resin (low-melting-point resin) contained in the central region A2 is preferably 150°C or less, more preferably 120°C or less, even more preferably 100°C or less, and particularly preferably 85 to 95°C. The melting point of the resin contained in the central region A2 may be approximately the same as (approximately ±5°C) the melting point of the resin contained in the separator 26. Although not particularly limited, examples of low-melting-point resins include polyethylene (PE), polyvinyl chloride (PVC), acrylic resin (PMMA), polystyrene (PS), etc. The low-melting-point resin is preferably a thermoplastic resin.

[0058] In order to achieve a higher level of effect from the technology disclosed herein, the difference between the melting point or softening point of the resin (high melting point resin) contained in the pair of end regions A1, A3 and the melting point of the resin (low melting point resin) contained in the central region A2 is preferably 5°C or more, more preferably 10°C or more, even more preferably 20°C or more, and particularly preferably 30°C or more.

[0059] The resin (high-melting-point resin) contained in the pair of end regions A1, A3 is typically a crystalline resin having a melting point, but may also be an amorphous resin without a melting point. Although not particularly limited, the melting point or softening point of the resin (high-melting-point resin) contained in the pair of end regions A1, A3 is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 130°C or higher, and particularly preferably 150°C or higher. This makes it easier to maintain the distance of thickness T between the adjacent second electricity storage device 120 when the temperature of the first electricity storage device 110 increases. The melting point of the high-melting-point resin is preferably approximately 250°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower.

[0060] Although not particularly limited, examples of high-melting-point resins include polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA), polyamideimide (PAI), polyimide (PI), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), phenolic resin (PF), ABS resin, polyethersulfone resin (PES), epoxy resin (EP), polyphenylene sulfide (PPS), polyurethane (PU), etc. The high-melting-point resin is preferably a thermosetting resin. However, the low-melting-point resin may be a thermoplastic resin.

[0061] The types and blending ratios of resins contained in the pair of end regions A1, A3 may be the same or different from each other. In some embodiments, the pair of end regions A1, A3 preferably have the same composition (types and blending ratios of resins contained). This makes it easier to maintain a balanced (stable) distance in thickness T between the adjacent second power storage device 120 in the height direction Z (first direction) when the temperature of the first power storage device 110 increases.

[0062] Preferably, the pair of end regions A1, A3 each have a certain level of rigidity or more. This makes it easier to maintain the distance of thickness T between the adjacent second power storage device 120 when the temperature of the first power storage device 110 rises. The rigidity can be expressed by Young's modulus (compressive elastic modulus), and it can be said that the higher the Young's modulus value, the higher the rigidity (the less likely it is to deform). Although not particularly limited, the pair of end regions A1, A3 each have a Young's modulus in the arrangement direction X measured in accordance with JIS K7161:2014 of preferably 0.5 GPa or more, more preferably 1.0 GPa or more, even more preferably 2.0 GPa or more, and particularly preferably 3.0 GPa or more. The Young's modulus in the arrangement direction X of the pair of end regions A1, A3 may be 100 GPa or less, 50 GPa or less, or 30 GPa or less.

[0063] In some embodiments, the pair of end regions A1, A3 preferably have a larger Young's modulus than the central region A2. This makes it easier to maintain the distance of thickness T between the first power storage device 110 and the adjacent second power storage device 120 when the temperature of the first power storage device 110 rises. The Young's modulus of the pair of end regions A1, A3 can be adjusted by the constituent materials of the pair of end regions A1, A3 (for example, the type of resin or the blending ratio of filler).

[0064] Although not particularly limited, as shown in FIG. 7, in the height direction Z (the first direction), when the overall height Ha (the overall length in the first direction) of the spacer 200 is taken as 100%, it is preferable that the height ratios H1 and H3 (%) of the pair of end regions A1 and A3 are each smaller than the height ratio H2 (%) of the central region A2 (that is, H1 < H2 and H3 < H2). By increasing the height ratio H2 of the central region A2, an air layer can be secured more widely in the height direction Z (the first direction) when the temperature of the first power storage device 110 rises.

[0065] The height ratio H2 (%) of the central region A2 is preferably 20% or more, more preferably 30% or more, further preferably 40% or more, and particularly preferably 50% or more. Thereby, the effects of the technology disclosed herein can be exerted at a high level. The height ratio H2 (%) of the central region A2 is preferably 90% or less, more preferably 80% or less, and further preferably 75% or less.

[0066] The height ratios H1 and H3 (%) of the pair of end regions A1 and A3 may be the same or different from each other. Although not particularly limited, the height ratios H1 and H3 of the pair of end regions A1 and A3 are each preferably 5% or more, and more preferably 10% or more. Thereby, when the temperature of the first power storage device 110 rises, it becomes easier to stably maintain the interval of the thickness T between the adjacent second power storage devices 120, so that the effects of the technology disclosed herein can be stably exerted at a high level. From the viewpoint of securing a wide central region A2, the height ratios H1 and H3 (%) of the pair of end regions A1 and A3 are preferably 35% or less, and more preferably 30% or less.

[0067] The power storage module 500 can be used for a variety of purposes, but can be suitably used, for example, as a power source (driving power source) for a motor mounted on a vehicle such as a passenger car, truck, etc. The type of vehicle is not particularly limited, but examples include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV).

[0068] While the preferred embodiments of the present invention have been described above, the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiments.

[0069] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: A power storage module comprising: a first power storage device and a second power storage device arranged along an arrangement direction; and a spacer arranged between the first power storage device and the second power storage device, wherein the spacer has, in a first direction perpendicular to the arrangement direction, a pair of end regions and a central region located between the pair of end regions, the pair of end regions and the central region containing different resins, and wherein, when the temperature of the first power storage device rises, the resin contained in the central region melts faster than the resin contained in the pair of end regions. Item 2: The electricity storage module according to Item 1, wherein the resin contained in the central region has a melting point of 100° C. or lower. Item 3: The energy storage module according to item 1 or 2, wherein the difference between the melting point or softening point of the resin contained in the pair of end regions and the melting point of the resin contained in the central region is 10°C or more. Item 4: The energy storage module according to item 1 or 2, wherein the spacer has a pair of rectangular opposing surfaces that are perpendicular to the arrangement direction and that face the first energy storage device and the second energy storage device, respectively, and the first direction is a direction that coincides with the direction of the short sides of the opposing surfaces. Item 5: The energy storage module according to item 1 or 2, wherein the pair of end regions have a larger Young's modulus than the central region. Item 6: The energy storage module according to item 1 or 2, wherein, when the overall length of the spacer in the first direction is 100%, the proportion of the length of the pair of end regions is smaller than the proportion of the length of the central region. [Explanation of symbols]

[0070] 10 Battery case 20a, 20b, 20c electrode body 100 Energy storage device 110 First electricity storage device 120 Second power storage device 200 spacer 210 Opposite Surface A1, A3 end area A2 central area 300 Restraint mechanism 500 Energy Storage Module X thickness direction (arrangement direction) Y width direction Z height direction (first direction)

Claims

1. a first power storage device and a second power storage device arranged along the arrangement direction; a spacer disposed between the first power storage device and the second power storage device; Equipped with the spacer has, in a first direction perpendicular to the arrangement direction, a pair of end regions and a central region located between the pair of end regions; the pair of end regions and the central region contain different resins, When the temperature of the first power storage device increases, the resin contained in the central region melts faster than the resin contained in the pair of end regions. Energy storage module.

2. The melting point of the resin contained in the central region is 100°C or less. The energy storage module according to claim 1 .

3. a difference between the melting point or softening point of the resin contained in the pair of end regions and the melting point of the resin contained in the central region being 10°C or more; The energy storage module according to claim 1 or 2.

4. the spacer has a pair of rectangular opposing surfaces that are perpendicular to the arrangement direction and that face the first power storage device and the second power storage device, respectively, and the first direction is a direction that coincides with a direction of short sides of the opposing surfaces. The energy storage module according to claim 1 or 2.

5. The pair of end regions have a larger Young's modulus than the central region. The energy storage module according to claim 1 or 2.

6. When the entire length of the spacer in the first direction is taken as 100%, the proportions of the lengths of the pair of end regions are each smaller than the proportion of the length of the central region. The energy storage module according to claim 1 or 2.

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