Electric storage module and method for manufacturing the same

Abstract

To provide a power storage module with a novel configuration, capable of leveling high rate resistances of a plurality of power storage devices.SOLUTION: A power storage module 500 disclosed herein includes a plurality of power storage devices 100 which are constrained along a predetermined arrangement direction. The plurality of power storage devices 100 each include: a flat square battery case 10; and an electrode body that has an active material coating part where a positive electrode active material layer and a negative electrode active material layer face each other, the active material coating part being accommodated inside the battery case 10 so as to face a flat surface 10a of the battery case 10. A low-temperature region A1 with relatively low temperature and a high-temperature region A2 with relatively high temperature exist in the power storage module 500 when the plurality of power storage devices 100 are charged and discharged. In the power storage module 500 disclosed herein, among the plurality of power storage devices 100, a first power storage device 110 disposed in the low-temperature region A1 has a lower surface pressure applied to the active material coating part than a second power storage device 120 disposed in the high-temperature region A2.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a power storage module including a plurality of power storage devices and a method for manufacturing the same.

Background Art

[0002] Conventionally, in power sources for vehicle driving and the like, a power storage module formed by electrically connecting a plurality of power storage devices (single cells) has been widely used. As related prior art documents, Patent Documents 1 to 4 can be cited.

[0003] For example, Patent Document 1 discloses a power storage module having a plurality of sub-modules and a housing that houses the plurality of sub-modules at predetermined positions. In Patent Document 1, each of the plurality of sub-modules includes a cell group in which a plurality of power storage devices (single cells) are arranged, and a restraint member that applies a restraint pressure in the arrangement direction to restrain the cell group. And, there is a region in the housing that is likely to become relatively low in temperature, and the sub-module arranged in the region that is likely to become low in temperature is configured such that the restraint pressure of the restraint member is relatively lower than that of other sub-modules. Patent Document 1 describes that by reducing the restraint pressure on the power storage device in a region (a region likely to become low in temperature) where the high-rate tolerance is likely to decrease in this way, the high-rate tolerance (increase in resistance when high-rate charge and discharge are repeated) of the plurality of power storage devices can be equalized.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology described in the above Patent Document 1, it is not possible to make the mutual restraint pressures different for a plurality of power storage devices included in one cell group. Therefore, according to the study by the present inventors, when a temperature distribution occurs within the cell group, it may be difficult to equalize the high-rate resistance of the plurality of power storage devices. Further, since a restraint member is essential for each cell group, the restraint member takes up space and the volume energy density of the entire power storage module decreases, or for example, when the power storage module is mounted on a moving body such as a vehicle, there is a risk that the weight increases and the fuel consumption deteriorates.

[0006] The present invention has been made in view of the above circumstances, and its main object is to provide a power storage module having a novel configuration capable of equalizing the high-rate resistance of a plurality of power storage devices and a method for manufacturing the same.

Means for Solving the Problems

[0007] According to the present invention, there is provided a power storage module in which a plurality of power storage devices are restrained along a predetermined arrangement direction. Each of the plurality of power storage devices included in this power storage module has a flat rectangular battery case and an electrode body having an active material coating portion in which a positive electrode active material layer and a negative electrode active material layer face each other, and the active material coating portion is housed inside the battery case so as to face the flat surface of the battery case. And in this power storage module, when charging and discharging a plurality of power storage devices, there are a low-temperature region where the temperature relatively decreases and a high-temperature region where the temperature relatively increases. And in this power storage module, among the plurality of power storage devices, the first power storage device arranged in the low-temperature region has a smaller surface pressure applied to the active material coating portion than the second power storage device arranged in the high-temperature region.

[0008] Further, the present invention provides a method for manufacturing a power storage module in which a plurality of power storage devices are constrained along a predetermined arrangement direction. Each of the plurality of power storage devices included in this power storage module has a flat rectangular battery case and an active material coating portion where a positive electrode active material layer and a negative electrode active material layer face each other, and the active material coating portion is accommodated inside the battery case so as to face the flat surface of the battery case. And this manufacturing method includes a preparation step of preparing a plurality of power storage devices, a temperature distribution prediction step of predicting the temperature distribution in the power storage module when the plurality of power storage devices are charged and discharged, and based on the temperature distribution, the surface pressure applied to the active material coating portion of the first power storage device arranged in the relatively low-temperature region becomes relatively small, and the surface pressure applied to the active material coating portion of the second power storage device arranged in the relatively high-temperature region becomes relatively large. And a construction step of constructing the power storage module.

[0009] As a result of various studies by the present inventors, it has been found that a power storage device with a small surface pressure applied to the active material coating portion is relatively superior in high-rate resistance compared to a power storage device with a large surface pressure applied to the active material coating portion. Therefore, in the present invention, a power storage device with a relatively small surface pressure (high high-rate resistance) applied to the active material coating portion is arranged in a low-temperature region where the high-rate resistance is likely to decrease. Thereby, the high-rate resistance of a plurality of power storage devices can be equalized. As a result, the high-rate resistance of the entire power storage module can be improved. Further, unlike the technology of Patent Document 1, it is not necessary to be restricted by the framework of "cell group", so the high-rate resistance of individual power storage devices can be adjusted flexibly. Furthermore, since the number of restraint members can be reduced compared to the technology of Patent Document 1, the volume energy density and fuel consumption can also be improved.

Brief Description of the Drawings

[0010]

Figure 1

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MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned in this specification and necessary for the implementation of the present invention (for example, the general configuration and manufacturing process of a power storage module or a power storage device that do not characterize the present invention) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The power storage module disclosed herein can be implemented based on the content disclosed herein and the common general knowledge in the relevant field.

[0012] In the following drawings, members and parts that perform the same function are denoted by the same reference numerals, and redundant descriptions may be omitted or simplified. Also, in this specification, the notation "A~B" indicating a range includes the meaning of "greater than or equal to A and less than or equal to B", as well as the meaning of "preferably greater than A" and "preferably less than B".

[0013] [Power storage module] FIG. 1 is a perspective view schematically showing a power storage module 500. The power storage module 500 includes, here, a plurality of power storage devices 100, a plurality of spacers 200, and a restraint mechanism 300. However, the plurality of spacers 200 and the restraint mechanism 300 are not essential and may be omitted in other embodiments.

[0014] In the following description, the reference numerals L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, up, and down, respectively, and the reference numerals X, Y, and Z in the drawings represent the short side direction, the long side direction orthogonal to the short side direction, and the up-down direction of the power storage device 100, respectively. The short side direction X is also the arrangement direction of the power storage devices 100. However, these are merely directions for convenience of explanation and do not limit the installation form of the power storage module 500 in any way.

[0015] 1. Power storage device First, the power storage device 100 in the power storage module 500 will be described. The power storage device 100 is a device capable of repeated charge and discharge. In this specification, the "power storage device" is a concept that includes secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors such as lithium-ion capacitors and electric double-layer capacitors. The plurality of power storage devices 100 are arranged here between a pair of end plates 310 along the arrangement direction X (in other words, the thickness direction X of the power storage device 100). The plurality of power storage devices 100 are preferably restrained by a restraint mechanism 300. Note that the shape, size, number, etc. of the plurality of power storage devices 100 are not limited to the embodiments disclosed in FIG. 1 and can be changed as appropriate.

[0016] Although not shown here, when the power storage module 500 is used, a plurality of power storage devices 100 are electrically connected to each other by a conductive member such as a bus bar. The connection method is not particularly limited, and may be, for example, series, parallel, or multi-series multi-parallel. In a preferred embodiment, a plurality of power storage devices 100 are connected in series. Thereby, for example, the output characteristics can be preferably improved to a level suitable for use in a moving body such as a vehicle. Also, in the case of series connection, deterioration of the performance of some of the power storage devices 100 is likely to lead to deterioration of the performance of the entire power storage module 500. Therefore, it is particularly effective to apply the technology disclosed herein.

[0017] FIG. 2 is a perspective view of the power storage device 100. As can be seen from FIGS. 1 and 2, the plurality of power storage devices 100 are all flat rectangular, and are of the same shape here. The plurality of power storage devices 100 are arranged such that the long side walls 12b described later are parallel to each other. The plurality of power storage devices 100 are arranged in the arrangement direction X such that the long side walls 12b face each other via the spacer 200 here.

[0018] FIG. 3 is a schematic longitudinal sectional view taken along line III-III of FIG. 2. As shown in FIG. 3, the power storage device 100 includes, here, a battery case 10, an electrode body 20, a positive electrode terminal 30, a negative electrode terminal 40, and a non-aqueous electrolyte (not shown). The power storage device 100 is configured by housing the electrode body 20 and the non-aqueous electrolyte in a battery case 10 to which the positive electrode terminal 30 and the negative electrode terminal 40 are attached. The power storage device 100 is typically a non-aqueous electrolyte secondary battery, and is a lithium ion secondary battery here. When the power storage device 100 is a lithium ion secondary battery, it is particularly effective to apply the technology disclosed herein.

[0019] The battery case 10 is a container that houses the electrode body 20 and the non-aqueous electrolyte. As shown in FIG. 2, the battery case 10 here has an outer shape that is flat, bottomed, and rectangular parallelepiped (rectangular). The material of the battery case 10 may be the same as those conventionally used, and there is no particular limitation. The battery case 10 is made of, for example, aluminum, aluminum alloy, iron, iron alloy, etc. As shown in FIG. 3, the battery case 10 includes an exterior body 12 having an opening 12h, and a sealing plate (lid body) 14 that seals the opening 12h. As shown in FIG. 2, the exterior body 12 includes a substantially rectangular bottom wall 12a having a long side and a short side, a pair of long side walls 12b extending from the long side of the bottom wall 12a and facing each other, and a pair of short side walls 12c extending from the short side of the bottom wall 12a and facing each other. The long side wall 12b is flat.

[0020] The sealing plate 14 is a plate-like member. The sealing plate 14 is substantially rectangular. As shown in FIG. 3, the sealing plate 14 is attached to the exterior body 12 so as to close the opening 12h of the exterior body 12. The battery case 10 is integrated by joining (preferably by welding) the sealing plate 14 to the periphery of the opening 12h of the exterior body 12. The battery case 10 is hermetically sealed. The sealing plate 14 is provided with a liquid injection hole 15, and two terminal lead-out holes 18, 19. The liquid injection hole 15 is for injecting the non-aqueous electrolyte after assembling the sealing plate 14 to the exterior body 12. The liquid injection hole 15 is sealed by a sealing member 16. The terminal lead-out holes 18, 19 penetrate the sealing plate 14 in the vertical direction Z.

[0021] The positive electrode terminal 30 is disposed at one end in the long side direction Y of the sealing plate 14 (the left end portion in FIGS. 2 and 3), and the negative electrode terminal 40 is disposed at the other end in the long side direction Y of the sealing plate 14 (the right end portion in FIGS. 2 and 3). As shown in FIG. 3, the positive electrode terminal 30 and the negative electrode terminal 40 respectively extend from the inside to the outside of the sealing plate 14 through the terminal lead-out holes 18 and 19. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are caulked to the peripheral portion surrounding the terminal lead-out holes 18 and 19 of the sealing plate 14 by caulking. Caulking portions 30c and 40c are formed at the ends on the side of the outer package 12 of the positive electrode terminal 30 and the negative electrode terminal 40 (the lower end portion in FIG. 3). Thereby, the positive electrode terminal 30 and the negative electrode terminal 40 are fixed to the sealing plate 14.

[0022] As shown in FIG. 3, the positive electrode terminal 30 is electrically connected to the positive electrode tab group 23 of the electrode body 20 through the positive electrode current collector portion 50 inside the outer package 12. The positive electrode terminal 30 is insulated from the sealing plate 14 by the internal insulating member 80 and the gasket 90. The negative electrode terminal 40 is electrically connected to the negative electrode tab group 25 of the electrode body 20 through the negative electrode current collector portion 60 inside the outer package 12. The negative electrode terminal 40 is insulated from the sealing plate 14 by the internal insulating member 80 and the gasket 90.

[0023] As shown in FIGS. 2 and 3, plate-shaped positive electrode external conductive members 32 and negative electrode external conductive members 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 members to which conductive members such as bus bars for electrically connecting a plurality of power storage devices 100 to each other are attached. The positive electrode external conductive member 32 and the negative electrode external conductive member 42 are insulated from the sealing plate 14 by the external insulating member 92. The power storage module 500 is connected in series, for example, by electrically connecting the positive electrode external conductive member 32 of one power storage device 100 and the negative electrode external conductive member 42 of the other power storage device 100 among the power storage devices 100 adjacent to each other in the arrangement direction X with a bus bar or the like.

[0024] FIG. 4 is a schematic diagram showing the configuration of the electrode body 20. As shown in FIG. 4, the electrode body 20 includes a positive electrode 22, a negative electrode 24, and a separator 26. Here, the electrode body 20 is a wound electrode body in which a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 are laminated via a strip-shaped separator 26 and wound around a winding axis WL. The electrode body 20 has a flat outer shape. Here, the electrode body 20 is disposed inside the exterior body 12 (battery case 10) in a direction in which the winding axis WL is substantially parallel to the long side direction Y. However, in other embodiments, the electrode body 20 may be disposed inside the exterior body 12 in a direction in which the winding axis WL is substantially parallel to the vertical direction Z. Further, the electrode body 20 may be a laminated electrode body in which a plurality of square (typically rectangular) positive electrodes and a plurality of square (typically rectangular) negative electrodes are stacked in an insulated state.

[0025] The configuration of the positive electrode 22 may be the same as that of the prior art. Here, the positive electrode 22 includes a positive electrode current collector 22c, and a positive electrode active material layer 22a and a positive electrode protective layer 22p fixed on 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 a metal foil. Here, the positive electrode current collector 22c is an aluminum foil.

[0026] A plurality of positive electrode tabs 22t are provided at one end (the left end in FIG. 4) in the long side direction Y of the positive electrode current collector 22c. The plurality of positive electrode tabs 22t protrude toward one side in the long side direction Y (the left side in FIG. 4). The plurality of positive electrode tabs 22t protrude in the long side direction Y more than the separator 26. Here, the positive electrode tab 22t is a part of the positive electrode current collector 22c and is made of a metal foil (aluminum foil). The plurality of positive electrode tabs 22t are laminated at one end (the left end in FIG. 4) in the long side 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 the positive electrode current collecting portion 50.

[0027] 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 capable of reversibly occluding and releasing 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 various additive components like a binder and a conductive material.

[0028] The positive electrode protective layer 22p is provided at the boundary portion between the positive electrode current collector 22c and the positive electrode active material layer 22a in the long side 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 (for example, 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 additive components.

[0029] The configuration of the negative electrode 24 may be the same as that of the conventional one. Here, the negative electrode 24 has a negative electrode current collector 24c and a negative electrode active material layer 24a fixed on 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, and more preferably made of a metal foil. Here, the negative electrode current collector 24c is a copper foil.

[0030] A plurality of negative electrode tabs 24t are provided at one end (the right end in FIG. 4) of the negative electrode current collector 24c in the long side direction Y. The plurality of negative electrode tabs 24t protrude toward one side in the long side direction Y (the right side in FIG. 4). The plurality of negative electrode tabs 24t protrude in the long side direction Y more than the separator 26. Here, the negative electrode tab 24t is a part of the negative electrode current collector 24c and is made of a metal foil (copper foil). The plurality of negative electrode tabs 24t are laminated at one end (the right end in FIG. 4) in the long side direction Y to form a negative electrode tab group 25. The negative electrode tab group 25 is provided at a position symmetric to the positive electrode tab group 23 in the long side direction Y. The negative electrode tab group 25 is electrically connected to the negative electrode terminal 40 via the negative electrode current collecting portion 60.

[0031] The negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction of the negative electrode current collector 24c. It is preferable that the length Ln in the long side direction Y of the negative electrode active material layer 24a is the same as or longer than the length Lp in the long side direction Y of the positive electrode active material layer 22a. The negative electrode active material layer 24a contains a negative electrode active material capable of reversibly occluding and releasing 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 various additive components such as a binder, a thickener, and a dispersant.

[0032] The separator 26 is disposed between the positive electrode 22 and the negative electrode 24. The separator 26 is a member that insulates the positive electrode 22 and the negative electrode 24. The configuration of the separator 26 may be the same as that of the conventional one. It is preferable that the length Ls in the long side direction Y of the separator 26 is the same as or longer than the length Ln in the long side direction Y of the negative electrode active material layer 24a. As the separator 26, for example, a resin porous sheet (micro porous membrane) made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable. The separator 26 may be provided with a functional layer (for example, an adhesive layer or a heat-resistant layer) on the surface of the porous sheet.

[0033] Here, as shown in FIGS. 3 and 4, in the electrode body 20 in the present embodiment, a region where the positive electrode active material layer 22a and the negative electrode active material layer 24a face each other is formed at the central portion in the long side direction Y. Hereinafter, the region where the positive electrode active material layer 22a and the negative electrode active material layer 24a face each other is referred to as the “active material coating portion 20a”. This active material coating portion 20a is the main place where the charge-discharge reaction (movement of charge carriers) occurs in the power storage device 100. When the electrode body 20 is housed inside the battery case 10, the active material coating portion 20a in FIGS. 3 and 4 faces the flat surface 10a (long side wall 12b of the exterior body 12) of the battery case 10 in FIG. 2.

[0034] The configuration of the non-aqueous electrolyte may be the same as that of the prior art. The non-aqueous electrolyte typically contains a non-aqueous solvent and a supporting salt (electrolyte salt). The non-aqueous solvent is, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as lithium hexafluorophosphate (LiPF6) or lithium bis(fluorosulfonyl)imide (LiFSI). The non-aqueous electrolyte may further contain additives as necessary. The non-aqueous electrolyte is typically liquid, but may also be gel-like. Further, in other embodiments, the power storage device 100 may be provided with a solid electrolyte instead of the non-aqueous electrolyte. In that case, the separator 26 can be omitted.

[0035] 2. Restraint mechanism Next, the restraint mechanism 300 will be described. As shown in FIG. 1, the restraint mechanism 300 is a member that restrains a plurality of power storage devices 100 along a predetermined arrangement direction X. Here, there is one restraint mechanism 300. The restraint 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 regarded as a housing for accommodating a plurality of power storage devices 100. The pair of end plates 310 and the pair of side plates 320 are preferably made of metal.

[0036] A pair of end plates 310 are arranged at both ends of the power storage module 500 in the array direction X. The pair of end plates 310 sandwich a plurality of power storage devices 100 and a plurality of spacers 200 in the array direction X. A 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 by a plurality of screws 330 such that the restraint load is about 10 to 15 kN, for example. Thereby, a uniform restraint load is applied to the plurality of power storage devices 100 from the array direction X, and the plurality of power storage devices 100 are integrally held. However, the configuration of the restraint mechanism is not limited to this. The restraint mechanism 300 may include, for example, a plurality of restraint bands, binding bars, etc. instead of the side plates 320.

[0037] 3. Spacer Next, the spacer 200 will be described. FIG. 5 is an enlarged plan view schematically showing the power storage module 500 of FIG. 1. As shown in FIGS. 1 and 5, the spacer 200 is a plate-like member interposed between each of the plurality of power storage devices 100 arranged along the array direction X. And, as shown in FIG. 5, the spacer 200 in the present embodiment has a convex portion 200b that presses the flat surface 10a (side wall surface 12b of the exterior body 12) of the battery case 10. Specifically, as shown in FIG. 5, in the power storage module 500 according to the present embodiment, the plurality of power storage devices 100 are arranged such that the flat surfaces 10a of the battery cases 10 face each other. And each of the plurality of spacers 200 includes a plate-like base portion 200a arranged along one flat surface 10a of a pair (two) of opposed power storage devices 100. In other words, the base portion 200a of the spacer 200 is a plate-like member arranged to cover the flat surface 10a of one battery case 10. And the convex portion 200b of the spacer 200 protrudes from the surface of the base portion 200a toward the flat surface 10a of the other power storage device 100. For this reason, in the power storage module 500 according to the present embodiment, the restraint pressure by the restraint mechanism 300 concentrates on the flat surface 10a in contact with the convex portion 200b of the spacer 200.

[0038] Here, in this embodiment, two types of spacers 200 composed of a first spacer 210 (see FIG. 6) and a second spacer 220 (see FIG. 7) are used. Here, the first spacer 210 is configured such that the number of convex portions 210b pressing the active material coating portion 20a via the flat surface 10a is relatively small. Further, the second spacer 220 is configured such that the number of convex portions 220b pressing the active material coating portion 20a is relatively large. This will be specifically described below.

[0039] FIG. 6 is a front view schematically showing the first spacer. As shown in FIG. 6, the first spacer 210 includes a plurality (four in the figure) of convex portions 210b. And each convex portion 210b is a convex strip extending along the vertical direction Z. And a part (two in the figure) of the plurality of convex portions 210b is formed at the left end L in the long side direction Y. Further, the remaining convex portions 210b are formed at the right end R in the long side direction Y. That is, as shown in FIG. 5, the first spacer 210 is configured to locally press both ends in the long side direction Y of the power storage device 100. Both ends of this power storage device 100 are surplus spaces 10b where the active material coating portion 20a is not arranged (see FIG. 3). That is, the first spacer 210 is configured to mainly press the surplus space 10b in the power storage device 100.

[0040] FIG. 7 is a front view schematically showing the second spacer. As shown in FIG. 7, the second spacer 220 also includes a plurality (four) of convex portions 220b. And each convex portion 220b is a convex strip extending along the vertical direction Z. And the convex portions 220b of the second spacer 220 are respectively formed at the central portion in the long side direction Y. That is, as shown in FIG. 5, the second spacer 220 is configured to locally press the central portion in the long side direction Y of the power storage device 100. The active material coating portion 20a of the electrode body 20 is arranged at the central portion of this power storage device 100 (see FIG. 3). That is, the second spacer 220 is configured to mainly press the active material coating portion 20a in the power storage device 100.

[0041] 4. Temperature Distribution of the Power Storage Module FIG. 8 is a plan view schematically showing the power storage module 500 and the cooling device 400. In FIG. 8, a detailed illustration of the upper surface of the power storage device 100 is omitted. As shown in FIG. 8, the cooling device 400 here includes an intake port IP, an exhaust port OP, an air-cooling fan 410, a temperature sensor 420, and a control device 430. The cooling device 400 is an air-cooling type cooling device that uses air as a refrigerant here. However, in other embodiments, the cooling device 400 may be a liquid-cooling type cooling device that uses a liquid refrigerant.

[0042] In the present embodiment, the intake port IP is provided on one side (front F side) in the arrangement direction X of the power storage module 500. The exhaust port OP is provided on the other side (rear Rr side) in the arrangement direction X. The air-cooling fan 410 is attached to the intake port IP. The air-cooling fan 410 is configured to send wind (air) to the intake port IP. The configuration of the air-cooling fan 410 is not limited, but for example, it includes an electric motor (not shown). The temperature sensor 420 is disposed at the center in the XY plane of the power storage module 500 here. The temperature sensor 420 is, for example, a thermocouple or a thermistor.

[0043] The control device 430 is electrically connected to the temperature sensor 420 and the electric motor of the air-cooling fan 410. When the control device 430 detects, for example, that the temperature in the power storage module 500 has become equal to or higher than a predetermined first temperature by the temperature sensor 420, the control device 430 operates the air-cooling fan 410. As a result, low-temperature air outside the power storage module 500 is supplied into the power storage module 500 from the intake port IP, and an air flow AF is generated in the power storage module 500. The supplied air passes through the inside of the power storage module 500 while cooling the power storage device 100, and is discharged from the exhaust port OP. When the control device 430 detects, for example, that the temperature in the power storage module 500 has become equal to or lower than a predetermined second temperature by the temperature sensor 420, the control device 430 stops the air-cooling fan 460. According to such an air-cooling type cooling device 400, the power storage device 100 can be cooled at low cost.

[0044] Incidentally, according to the study by the present inventors, inside a power storage module 500 equipped with a cooling mechanism such as a cooling device 400, for example, a temperature distribution occurs during charging and discharging of a plurality of power storage devices 100, and a low-temperature region A1 where the temperature becomes relatively low and a high-temperature region A2 where the temperature becomes relatively high may occur. Specifically, when the power storage device 100 generates heat due to charging and discharging, adjacent power storage devices 100 heat each other. As a result, in the central portion in the arrangement direction X, a chain reaction of heat generation occurs between the power storage devices 100, and the temperature tends to become relatively high. On the other hand, both ends in the arrangement direction X (the front F portion and the rear Rr portion in FIG. 8) have higher heat dissipation than the central portion, so chain reaction of heat generation is less likely to occur. Therefore, at both ends in the arrangement direction X, the temperature tends to become relatively low.

[0045] Particularly in the present embodiment, an intake port IP through which a refrigerant (air) is supplied and an air-cooling fan 410 are arranged on the front F side in the arrangement direction X, and an exhaust port OP is arranged on the rear Rr side in the arrangement direction X. For this reason, both ends in the arrangement direction X tend to be at a low temperature. Therefore, the central portion in the arrangement direction X becomes a high-temperature region A2 where the temperature is relatively high, and both ends in the arrangement direction X (the front F portion and the rear Rr portion in FIG. 8) tend to become a low-temperature region A1 where the temperature is relatively low. In particular, the front F portion in the arrangement direction X where the intake port IP and the air-cooling fan 410 are arranged is most likely to be at the lowest temperature. That is, in the present embodiment, at least the front F side in the arrangement direction X tends to become a low-temperature region A1 where the temperature is relatively low.

[0046] As described in Patent Document 1 and the like, when such a temperature distribution occurs in the power storage module 500, variations may occur in the high-rate tolerance of the power storage device 100. Specifically, the high-rate tolerance of the power storage device 100 may decrease in the low-temperature region A1. In this case, if the charge and discharge of the entire power storage module 500 are controlled based on the high-rate tolerance of the power storage device 100 in the low-temperature region A1, the high high-rate tolerance of the power storage device 100 in the high-temperature region A2 cannot be fully utilized. On the other hand, if the high-rate tolerance of the power storage device 100 in the high-temperature region A2 is used as a reference, a high voltage is applied to the power storage device 100 in the low-temperature region A1, and high-rate degradation is likely to be accelerated. Thus, when a temperature distribution occurs in the power storage module 500, the high-rate tolerance of the entire power storage module 500 may be reduced due to being restricted by the high-rate tolerance of the power storage device 100 in the low-temperature region A1. Furthermore, when the power storage module is mounted on a moving body such as a vehicle, there is also a possibility that the fuel consumption deteriorates.

[0047] In contrast, in the power storage module 500 according to the present embodiment, the first power storage device 110 disposed in the low-temperature region A1 is configured such that the surface pressure applied to the active material coating portion 20a is smaller than that of the second power storage device 120 disposed in the high-temperature region A2. Specifically, in the power storage module 500 according to the present embodiment, the first spacer 210 is disposed in the low-temperature region A1. As a result, in the first power storage device 110, the surface pressure applied to the surplus space 10b becomes stronger, so that the surface pressure applied to the active material coating portion 20a becomes relatively smaller. Furthermore, in the power storage module 500 according to the present embodiment, the second spacer 220 is disposed in the high-temperature region A2. As a result, in the second power storage device 120, the surface pressure applied to the active material coating portion 20a becomes relatively larger. And as shown in the test examples described later, the inventor has confirmed that the high-rate tolerance increases as the surface pressure applied to the active material coating portion 20a decreases. Therefore, according to the present embodiment, the first power storage device 110 having relatively high high-rate tolerance can be disposed in the relatively low-temperature low-temperature region A1 (both ends in the arrangement direction X), and the second power storage device 120 having relatively low high-rate tolerance can be disposed in the relatively high-temperature high-temperature region A2 (central portion in the arrangement direction X).

[0048] According to such a configuration, the high-rate tolerance of the plurality of power storage devices 100 can be leveled at a high level. As a result, the acceleration of deterioration can be suppressed, and the high-rate tolerance of the entire power storage module 500 can be improved. Further, unlike the technology of Patent Document 1, since it is not necessary to be restricted by the framework of "cell group", the high-rate tolerance of the plurality of power storage devices 100 can be flexibly adjusted according to the temperature distribution in the power storage module 500. Therefore, in some cases, the high-rate tolerance of the plurality of power storage devices 100 can be leveled with higher accuracy than the technology of Patent Document 1. Furthermore, since the number of restraint mechanisms 300 can be reduced compared to the technology of Patent Document 1, the volumetric energy density and fuel consumption can also be improved. In addition, the number of components can be reduced, and the manufacturing cost can be reduced.

[0049] Incidentally, when the area of the active material coating portion 20a is 100%, the pressing area of the active material coating portion 20a by the first spacer 210 is preferably 30% or less, more preferably 20% or less, still more preferably 10% or less, and particularly preferably 5% or less. Thereby, the high-rate tolerance of the first power storage device 110 can be more suitably improved, and the high-rate tolerance of the entire power storage module 500 can be leveled at a higher level. On the other hand, the pressing area of the active material coating portion 20a by the first spacer 210 may be 0% (not pressing the active material coating portion 20a), may be 1% or more, or may be 2.5% or more.

[0050] Also, the pressing area by the second spacer 220 is preferably adjusted as appropriate in relation to the pressing area by the first spacer 210 so as to equalize the high-rate tolerance of the entire power storage module 500. As an example, the pressing area of the second spacer 220 against the active material coating part 20a is preferably 1% or more, more preferably 2% or more, still more preferably 5% or more, and particularly preferably 10% or more. Thereby, since it is easy to make the high-rate tolerance of the second power storage device 120 lower than that of the first power storage device 110, it becomes easy to equalize the high-rate tolerance of the entire power storage module 500. On the other hand, the pressing area of the second spacer 220 against the active material coating part 20a is preferably 50% or less, more preferably 40% or less, still more preferably 35% or less, and particularly preferably 30% or less. Thereby, since the number of formed convex portions 220b decreases, a certain gap can be secured between the second spacer 220 and the second power storage device 120. Thereby, the active material coating part 20a where heat generation is likely to occur can be suitably cooled.

[0051] [Method for manufacturing a power storage module] Next, a method for manufacturing a power storage module 500 including a plurality of power storage devices 100 will be described. The power storage module 500 can be manufactured, for example, by a manufacturing method including: (Step A) a preparation step of preparing a first power storage device 110 and a second power storage device 120; (Step B) a temperature distribution prediction step of predicting the temperature distribution within the power storage module 500; and (Step C) a construction step of constructing the power storage module 500 by combining the first power storage device 110 and the second power storage device 120. The manufacturing method disclosed herein may further include other steps at any stage. Note that the order of (Step A) the preparation step and (Step B) the temperature distribution prediction step is not particularly limited. For example, (Step B) the temperature distribution prediction step may be performed after (Step A) the preparation step, or (Step A) the preparation step may be performed after (Step B) the temperature distribution prediction step.

[0052] (Step A) In the preparation step, a plurality of power storage devices 100 are prepared. In the present embodiment, the (Step A) preparation step includes, in this order, (A-1) a housing step of housing the electrode body 20 in the battery case 10, and (A-2) a conditioning step.

[0053] (A-1) In the housing step, the electrode body 20 is housed in the battery case 10 together with the electrolytic solution. In a preferred embodiment, first, the positive tab group 23 of the electrode body 20 is joined to the positive current collector 50, and the negative tab group 25 of the electrode body 20 is joined to the negative current collector 60. Thereby, the sealing plate 14 and the electrode body 20 are integrated. Next, the sealing plate 14 is placed over the opening 12h of the outer package 12, and the electrode body 20 is disposed inside the outer package 12. Next, the sealing plate 14 is welded to the periphery of the opening 12h of the outer package 12 to integrate the outer package 12 and the sealing plate 14. Next, the electrolytic solution is injected into the battery case 10 through the liquid injection hole 15 of the sealing plate 14. Thereby, a precursor (battery assembly) of the power storage device 100 is produced.

[0054] (A-2) In the conditioning step, the produced battery assembly is charged at least once. Preferably, the produced battery assembly is charged and discharged at least once. The charging and discharging of the battery assembly can be performed in the same manner as in the prior art. Typically, an external power source is connected between the positive terminal 30 and the negative terminal 40, and charging or discharging is performed until the terminals reach a predetermined state of charge (SOC). Then, the battery case 10 is hermetically sealed. In the above manner, a plurality of power storage devices 100 can be prepared.

[0055] (Project B) In the temperature distribution prediction process, the temperature distribution within the power storage module 500 is predicted when a plurality of power storage devices 100 are charged and discharged. That is, for example, in the aspect shown in FIG. 8, both end portions in the array direction X (particularly the front F portion in the array direction X) are likely to be low-temperature regions A1. However, the temperature distribution within the power storage module 500 can also change depending on the configuration of the cooling device 400 (for example, the intake port IP, the exhaust port OP, the installation position and number of the air-cooling fans 410) and the heat dissipation path. Also, for example, the range (length in the array direction X) of the low-temperature region A1 can change depending on, for example, the number of power storage devices 100 and the charge-discharge conditions. Therefore, it is preferable to predict the temperature distribution within the power storage module 500 during charge and discharge through preliminary experiments or simulations using commercially available analysis software. In particular, it is preferable to construct a power storage module for preliminary tests that mimics the power storage module 500, measure the temperature distribution actually, and predict the temperature distribution within the power storage module 500 based on the actual measurement.

[0056] In a preferred embodiment, first, a plurality of power storage devices for preliminary tests different from the first power storage device 110 and the second power storage device 120 manufactured in the preparation process are prepared, and temperature sensors are attached to each of them. Next, using the plurality of power storage devices for preliminary tests, a power storage module for preliminary tests that mimics the power storage module 500 is assembled. Next, the plurality of power storage devices for preliminary tests are actually charged and discharged (preferably at a high rate), and the temperature distribution at this time is acquired. The charge-discharge conditions are preferably conditions assuming the actual usage mode. Then, based on the acquired temperature distribution, the temperature distribution within the power storage module 500 is predicted and divided, for example, into a low-temperature region A1 and a high-temperature region A2 (for example, divided into two parts).

[0057] (Project C) In the construction process, the power storage module 500 is constructed such that a relatively small surface pressure is applied to the active material coating portion 20a of the power storage device 100 (first power storage device 110) disposed in the low temperature region A1. Specifically, in this construction process, first, when arranging a plurality of first power storage devices 110 in the low temperature region A1, a first spacer 210 is interposed between each of the first power storage devices 110. Next, when arranging a plurality of second power storage devices 120 in the high temperature region A2, a second spacer 220 is interposed between each of the second power storage devices 120. Then, using the restraint mechanism 300, these power storage devices 100 and spacers 200 are restrained along the arrangement direction X. At this time, in the first power storage device 110, the surplus space 10b inside the battery case 10 is mainly pressed by the convex portion 210b of the first spacer 210. On the other hand, in the second power storage device 120, the active material coating portion 20a of the electrode body 20 is mainly pressed through the battery case 10 by the convex portion 220b of the second spacer 220. As a result, in the power storage module 500 after construction, the surface pressure applied to the active material coating portion 20a of the first power storage device 110 disposed in the low temperature region A1 is smaller than that of the second power storage device 120 disposed in the high temperature region A2. Thereby, the high rate tolerance of the plurality of power storage devices 100 included in the power storage module 500 can be leveled at a high level.

[0058] [Applications of the Power Storage Module] The power storage module 500 can be used for various applications. Since it has excellent high rate tolerance, it can be suitably used as a power source (driving power source) for motors mounted on vehicles that require high output, such as vehicles like passenger cars and trucks. The type of vehicle is not particularly limited, and examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), etc. By mounting the power storage module 500 on a moving body such as a vehicle, the fuel consumption (electricity cost) of the moving body can be improved.

[0059] Hereinafter, several test examples related to the present invention will be described, but the present invention is not intended to be limited to such test examples.

[0060] In this test example, three types of spacers with different convex portion formation positions were prepared, and the high-rate resistance of the power storage device pressed through each spacer was confirmed. Specifically, first, a power storage device (lithium-ion secondary battery) in which an electrode body was housed in a battery case was manufactured. Next, the power storage device was sandwiched between a pair of spacers and constrained with a pressure of 10 kN. At this time, in this test example, a spacer having four convex portions was used, and the formation positions of the convex portions were made different among Examples 1 to 3 (see Table 1). Note that the configurations other than the spacers are common in all examples. Next, in a temperature environment of 25°C, the power storage device was adjusted to a state of SOC 50%, a constant current discharge was performed at 150 A for 10 seconds, and the discharge resistance was measured. Next, the battery voltage ΔV that dropped in 10 seconds was read, and based on the battery voltage ΔV and the discharge current value (150 A), the IV resistance (initial resistance) was calculated.

[0061] Next, in a temperature environment of 25°C, the power storage device was adjusted to a state of SOC 50%, constant current charging was performed at a charging rate of 150 A for 10 seconds, then paused for 5 seconds, and then constant current discharging was performed at a discharging rate of 10 A for 150 seconds, followed by a 5-second pause. One cycle of charge and discharge was defined as one cycle, and this was repeated 1000 times to conduct a high-rate durability test. Then, after the high-rate durability test, the IV resistance was measured in the same manner as the initial resistance, and the resistance increase rate was calculated from the ratio of the IV resistance after the durability test to the initial resistance (IV resistance after the durability test / initial resistance). The results are shown in Table 1. Note that Table 1 shows the relative values when the resistance increase rate of Example 3 is set to 1.00 (reference).

[0062]

Table 1

[0063] As shown in Table 1, it was confirmed that as the surface pressure applied to the active material coating portion of the electrode body decreases, the resistance increase rate after the high-rate durability test is suppressed. From this, it was found that the high-rate tolerance of the power storage device can be controlled by adjusting the position of the convex portion of the spacer to control the surface pressure applied to the active material coating portion.

[0064] As described above, the preferred embodiments of the present invention have been explained, but 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 content disclosed in this specification and the common general knowledge in the art. The technology described in the claims includes various modifications and changes of the above-exemplified embodiments. For example, it is possible to replace a part of the above-described embodiments with other modified examples, and it is also possible to add other modified examples to the above-described embodiments. Further, if the technical features are not described as essential, they can be appropriately deleted.

[0065] (1) For example, in the embodiment of FIG. 8 described above, both end portions in the array direction X (the front F portion and the rear Rr portion in FIG. 8) are relatively low-temperature regions A1 with a relatively low temperature, and the central portion in the array direction X is a relatively high-temperature region A2 with a relatively high temperature. However, it is not limited to this. As described above, the temperature distribution within the power storage module 500 can vary depending on the configuration of the cooling device 400 (for example, the intake port IP, the exhaust port OP, the installation position and number of the air-cooling fans 410), the number of power storage devices 100, the charge-discharge conditions, and the like. Further, in the embodiment of FIG. 8 described above, the inside of the power storage module 500 is divided into two temperature regions, namely, the low-temperature region A1 and the high-temperature region A2, and furthermore, the temperature distribution is symmetric with respect to the array direction X. However, it is not limited to this. For example, the inside of the power storage module 500 can also be divided into three or more temperature regions. In that case, in the embodiment of FIG. 8, the low-temperature region A1 on the rear Rr side in the array direction X may be set as a medium-temperature region A3 that is higher in temperature than the low-temperature region A1 and lower in temperature than the high-temperature region A2. Also, when the cooling path and the heat dissipation path are complex, the temperature distribution may be random, for example, the low-temperature region A1 and the high-temperature region A2 may appear alternately. Hereinafter, several specific modification examples will be described with reference to FIGS. 9 to 12. Note that in FIGS. 9 to 12, the illustration of the cooling device is omitted.

[0066] (First Modification Example) FIG. 9 is a plan view of a power storage module 500a according to the first modification example. As described above, it is known that chain heat generation is likely to occur between the power storage devices 100 at the central portion in the array direction X. Therefore, although not shown in FIG. 9, an intake port IP for supplying a refrigerant (air) and / or an air-cooling fan 410 may be additionally installed at the central portion in the array direction X, and the central portion may be strongly cooled. Then, as shown in FIG. 9, the temperature distribution of the power storage module 500a is, contrary to FIG. 8, such that the central portion in the array direction X becomes a relatively low-temperature region A1, and both end portions in the array direction X (the front F portion and the rear Rr portion in FIG. 9) may become relatively high-temperature regions A2.

[0067] In such cases, as shown in FIG. 9, a first power storage device 110 with a small surface pressure (high high-rate tolerance) applied to the active material coating section 20a is arranged at the center of the array direction X in the low-temperature region A1, and a second power storage device 120 with a large surface pressure (low high-rate tolerance) applied to the active material coating section 20a is arranged at both ends of the array direction X in the high-temperature region A2.

[0068] (Second and third modified examples) FIG. 10 is a plan view of a power storage module 500b according to the second modified example. FIG. 11 is a plan view of a power storage module 500c according to the third modified example. For example, when the air-cooling fan 410 installed on the front F side in the array direction X of FIG. 8 is powerful and has a high cooling capacity, as shown in FIGS. 10 and 11 respectively, the temperature distribution in the power storage modules 500b and 500c is such that the front F part in the array direction X becomes a relatively low-temperature region A1, and the rear Rr part in the array direction X can become a relatively high-temperature region A2.

[0069] In such cases, as shown in FIGS. 10 and 11, a first power storage device 110 with a small surface pressure (high high-rate tolerance) applied to the active material coating section 20a is arranged at the front F part in the array direction X in the low-temperature region A1, and a second power storage device 120 with a large surface pressure (low high-rate tolerance) applied to the active material coating section is arranged at the rear Rr part in the array direction X in the high-temperature region A2.

[0070] Also, the distribution between the low-temperature region A1 and the high-temperature region A2 can vary depending on, for example, the number of power storage devices 100, the charge / discharge conditions, etc. Therefore, the low-temperature region A1 and the high-temperature region A2 may be provided uniformly in the array direction X as shown in FIG. 10, or may be provided non-uniformly in the array direction X as shown in FIG. 11. In other words, the number of the first power storage devices 110 and the number of the second power storage devices 120 included in the power storage module 500 may be the same or different.

[0071] (Fourth Modified Example) FIG. 12 is a plan view of a power storage module 500d according to the fourth modified example. As shown in FIG. 12, the temperature distribution of the power storage module 500d is here divided in more detail than in FIG. 8. That is, both end portions in the array direction X (the front F portion and the rear Rr portion in FIG. 9) are relatively low-temperature regions A1 where the temperature is relatively low, the central portion in the array direction X is a relatively high-temperature region A2 where the temperature is relatively high, and between the low-temperature region A1 and the high-temperature region A2 is a medium-temperature region A3 where the temperature is higher than that of the low-temperature region A1 and lower than that of the high-temperature region A2.

[0072] In such a case, as shown in FIG. 12, first power storage devices 110 with a relatively small surface pressure applied to the active material coating portion 20a (high high-rate resistance) are arranged at both end portions in the array direction X, which are the low-temperature regions A1, and second power storage devices 120 with a relatively large surface pressure applied to the active material coating portion 20a (low high-rate resistance) are arranged at the central portion in the array direction X, which is the high-temperature region A2. Then, in the medium-temperature region A3, which is intermediate between the low-temperature region A1 and the high-temperature region A2, a third power storage device 130 having a smaller surface pressure applied to the active material coating portion 20a than the second power storage device 120 and a larger surface pressure applied to the active material coating portion 20a than the first power storage device 110 may be arranged. Note that as the spacer 200 for pressing the third power storage device 130, it is preferable to use a third spacer 230 in which two convex portions 230b1 are arranged at both end portions and the remaining two convex portions 230b2 are arranged at the central portion. The third spacer 230 having such a configuration presses the surplus space 10b of the third power storage device 130 with the convex portions 230b1 at both end portions and presses the active material coating portion 20a of the third power storage device 130 with the convex portions 230b2 at the central portion. Thereby, a plurality of power storage devices 100 can be arranged so that the surface pressure applied to the active material coating portion 20a decreases in the order of the high-temperature region A2, the medium-temperature region A3, and the low-temperature region A1, here from the central portion to both end portions in the array direction X.

[0073] In FIG. 12, the inside of the power storage module 500 is divided into three temperature regions, but it is of course possible to divide it into four or more temperature regions. By finely dividing the inside of the power storage module 500 according to the temperature distribution in this way, the effects of the technology disclosed herein can be exhibited at a high level, and the high-rate resistance of the entire power storage module 500 can be improved better.

[0074] (2) For example, in the above-described embodiment, by varying the formation position of the convex portion 200b of the spacer 200 between the first power storage device 110 and the second power storage device 120, the surface pressure applied to the active material coating portion 20a of the first power storage device 110 is relatively reduced. However, the technology disclosed herein is not limited to the above-described embodiment. For example, the number of the convex portions 200b of the spacer 200 may be varied between the first power storage device 110 and the second power storage device 120. Even in this case, the surface pressure applied to the active material coating portion 20a can be varied between the first power storage device 110 and the second power storage device 120. Further, the means for adjusting the surface pressure applied to the active material coating portion 20a is not limited to the spacer 200 described above. For example, a plate-like member (buffer member) having a plurality of convex portions may be housed inside the battery case, and the positions of the convex portions of the buffer member inside the battery case may be varied between the first power storage device 110 and the second power storage device 120. It is understood that the leveling of the high-rate resistance can be achieved even in a form using such a buffer member.

[0075] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: A power storage module in which a plurality of power storage devices are constrained along a predetermined arrangement direction, each of the plurality of power storage devices having a flat rectangular battery case and an electrode body housed inside the battery case such that an active material coating part where a positive electrode active material layer and a negative electrode active material layer face each other faces the flat surface of the battery case. In the power storage module, there are a low temperature region where the temperature relatively decreases and a high temperature region where the temperature relatively increases during charging and discharging of the plurality of power storage devices. Among the plurality of power storage devices, the first power storage device arranged in the low temperature region has a smaller surface pressure applied to the active material coating part than the second power storage device arranged in the high temperature region. Power storage module. Item 2: Further comprising a plurality of spacers interposed between each of the plurality of power storage devices, each of the plurality of spacers having a convex portion that presses the flat surface of the battery case, and the first spacer arranged in the low temperature region has fewer convex portions that press the active material coating part via the flat surface than the second spacer arranged in the high temperature region. The power storage module according to Item 1. Item 3: The power storage module according to Item 2, wherein the pressing area of the active material coating part by the first spacer is 30% or less of the total area of the active material coating part. Item 4: The power storage module according to Item 2 or 3, wherein the pressing area of the active material coating part by the second spacer is 1% or more and 50% or less of the total area of the active material coating part. Item 5: The power storage module according to any one of Items 1 to 4, wherein the first power storage device and the second power storage device are connected in series. Item 6: In the power storage module, there is a medium temperature region between the low temperature region and the high temperature region, where the temperature is higher than that of the low temperature region and lower than that of the high temperature region. Among the plurality of power storage devices, the third power storage device arranged in the medium temperature region has a larger surface pressure applied to the active material coating part than the first power storage device and a smaller surface pressure applied to the active material coating part than the second power storage device. The power storage module according to any one of Items 1 to 5. Item 7: A method for manufacturing a power storage module in which a plurality of power storage devices are constrained along a predetermined arrangement direction, wherein each of the plurality of power storage devices has a flat rectangular battery case and an electrode body housed inside the battery case such that an active material coating part where a positive electrode active material layer and a negative electrode active material layer face each other faces the flat surface of the battery case, the method including: a preparation step of preparing a plurality of the power storage devices; a temperature distribution prediction step of predicting a temperature distribution in the power storage module when the plurality of power storage devices are charged and discharged; and a construction step of constructing the power storage module such that a surface pressure applied to the active material coating part of a first power storage device disposed in a relatively low-temperature region becomes relatively small and a surface pressure applied to the active material coating part of a second power storage device disposed in a relatively high-temperature region becomes relatively large based on the temperature distribution.

Explanation of Signs

[0076] 10 Battery case 20 Electrode body 22 Positive electrode 24 Negative electrode 100 Power storage device 110 First power storage device 120 Second power storage device 130 Third power storage device 200 Spacer 300 Constraint mechanism 400 Cooling device 410 Air-cooling fan 500 Power storage module A1 Low-temperature region A2 High-temperature region A3 Medium-temperature region

Claims

1. A power storage module in which a plurality of power storage devices are constrained along a predetermined arrangement direction, each of the plurality of power storage devices, has a flat rectangular battery case, and an electrode body having an active material coating portion where a positive electrode active material layer and a negative electrode active material layer face each other, and the active material coating portion is accommodated inside the battery case so as to face the flat surface of the battery case, and, in the power storage module, when the plurality of power storage devices are charged and discharged, there are a low temperature region where the temperature relatively decreases and a high temperature region where the temperature relatively increases, among the plurality of power storage devices, the first power storage device arranged in the low temperature region has a smaller surface pressure applied to the active material coating portion than the second power storage device arranged in the high temperature region. A power storage module.

2. further comprising a plurality of spacers interposed between each of the plurality of power storage devices, each of the plurality of spacers has a convex portion that presses the flat surface of the battery case, the first spacer arranged in the low temperature region has a smaller number of convex portions that press the active material coating portion through the flat surface than the second spacer arranged in the high temperature region. The power storage module according to claim 1.

3. The power storage module according to claim 2, wherein the pressing area of the active material coating portion by the first spacer is 30% or less of the total area of the active material coating portion.

4. The power storage module according to claim 3, wherein the pressing area of the active material coating portion by the second spacer is 1% or more and 50% or less of the total area of the active material coating portion.

5. The power storage module according to claim 1, wherein the first power storage device and the second power storage device are connected in series.

6. in the power storage module, there is a medium temperature region between the low temperature region and the high temperature region, and the temperature of the medium temperature region is higher than that of the low temperature region and lower than that of the high temperature region, among the plurality of power storage devices, the third power storage device arranged in the medium temperature region has a larger surface pressure applied to the active material coating portion than the first power storage device and a smaller surface pressure applied to the active material coating portion than the second power storage device. The power storage module according to any one of claims 1 to 5.

7. A method for manufacturing a power storage module in which a plurality of power storage devices are constrained along a predetermined arrangement direction, each of the plurality of power storage devices, has a flat rectangular battery case, An electrode body having an active material coating portion where a positive electrode active material layer and a negative electrode active material layer face each other, and the active material coating portion is housed inside the battery case so as to face the flat surface of the battery case having a preparation step of preparing a plurality of the power storage devices a temperature distribution prediction step of predicting the temperature distribution in the power storage module when the plurality of power storage devices are charged and discharged a construction step of constructing the power storage module such that, based on the temperature distribution, the surface pressure applied to the active material coating portion of the first power storage device disposed in a relatively low-temperature region becomes relatively small, and the surface pressure applied to the active material coating portion of the second power storage device disposed in a relatively high-temperature region becomes relatively large including a method for manufacturing a power storage module

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