JP2012014938A - Battery module - Google Patents

Abstract

When a battery module is formed by laminating a plurality of rectangular cells, it suppresses variations in temperature inside the laminate without reducing space efficiency.
A battery module 10 includes a cell group 14 in which n (n ≧ 2) cells 12 and (n + 1) heat insulating materials (spacers 30 and end plates 22) are alternately stacked. . Each of the heat insulating materials has a refrigerant flow path, and the thermal conductivity decreases from the center in the stacking direction of the cell group 14 toward both ends. The heat conductivity measured by JIS A 1412 of the heat insulating material arranged at both ends of the cell group 14 is 0.01 to 10 W / mK.
[Selection] Figure 1

Description

  The present invention relates to a battery module, and more specifically to a technique for extending the life of a battery module including a secondary battery.

  A battery assembly in which a large number of batteries (secondary batteries) are connected in series or a combination of parallel and series is used as a power source for driving electric vehicles and hybrid vehicles. A battery module obtained by adding a safety device or the like for ensuring safety during use to the battery assembly is referred to as a battery module.

  Some of such battery modules are obtained by stacking a plurality of flat rectangular batteries in order to increase space efficiency (battery capacity per unit volume of the battery module). In such a battery module, the batteries arranged at both ends in the stacking direction are most likely to dissipate heat, and it is relatively easy to suppress a temperature rise due to heat generation during charging / discharging of the battery. On the other hand, the battery laminated on the inner side is difficult to dissipate heat, and heat from the battery adjacent to the battery is transmitted, so that it is difficult to suppress the temperature rise.

  As a result, temperature variations occur inside the battery module, and some batteries may deteriorate early. If some of the batteries deteriorate early, the battery module cannot maintain its intended performance, resulting in a short life as a whole.

  In relation to this point, Patent Document 1 proposes that a refrigerant passage is formed between the stacked batteries, and that the width of the passage is increased toward the center in the stacking direction. . Thereby, the flow volume of the refrigerant path close to the center in the stacking direction can be increased, and the battery in the center can be cooled better. As a result, it is claimed that variations in battery temperature can be suppressed.

  In Patent Document 2, a heat insulating spacer is arranged between each stacked battery, and the heat insulating property of the heat insulating spacer arranged near the center is made larger than the heat insulating property of the heat insulating spacer arranged near the end. It has been proposed. Accordingly, it is claimed that the battery in the center portion is prevented from being heated by the heat generated by the surrounding batteries, so that variations in battery temperature can be suppressed.

JP 2003-331932 A JP 2005-317455 A

  However, in Patent Document 1, it is necessary to considerably increase the width of the refrigerant passage closer to the center of the battery stack, and the volume of the battery module increases as a whole. Since the unnecessary increase in the volume of the battery module is directly related to the deterioration of the space efficiency, it is difficult to implement in the present situation where the improvement of the space efficiency is required.

  On the other hand, in the prior art proposed in Patent Document 2, since there is no refrigerant passage between the batteries, when the outside air temperature is high, the battery in the center part becomes high temperature, and the shortening of the battery module life is promoted. There is a risk. In addition, because the heat insulating property of the heat insulating spacer arranged at the end is small, the battery temperature of the battery in the vehicle-mounted battery module, etc. becomes too low in the cold district in winter, etc. May not be able to be supplied to the vehicle.

  An object of the present invention is to suppress variation in temperature inside a stacked body without reducing space efficiency when the battery module is configured by stacking a plurality of rectangular cells.

One aspect of the present invention is a battery module including a laminate in which n (n ≧ 4) rectangular cells and (n−1) first heat insulating materials are alternately stacked,
Each of the (n-1) first heat insulators has a refrigerant flow path, and the thermal conductivity measured by JIS A 1412 decreases from the center in the stacking direction of the stack toward both ends. The present invention relates to a battery module.

Another aspect of the present invention is a battery module including a laminate in which n (n ≧ 4) rectangular cells and (n−1) first heat insulating materials are alternately stacked,
The (n-1) first heat insulating materials are formed of the same material, each has a refrigerant flow path, and the amount of heat conduction decreases from the center in the stacking direction of the stacked body toward both ends. The present invention relates to a battery module in which each thickness is adjusted.

  According to the battery module of the present invention, when the battery module is configured by stacking a plurality of rectangular cells, it is possible to suppress variations in temperature inside the stacked body without reducing space efficiency. it can.

It is a perspective view which shows the external appearance of the battery module which concerns on one Embodiment of this invention. It is a perspective view which shows the internal structure of the battery module of FIG. It is a perspective view which shows a restraint member. It is a perspective view which shows a part of cell group.

  The present invention relates to a battery module including a laminate in which n (n ≧ 4) rectangular cells and (n−1) first heat insulating materials or spacers are alternately laminated. Each of the (n-1) first heat insulating materials has a refrigerant flow path, and the thermal conductivity measured by JIS A 1412 decreases from the center in the stacking direction of the stacked body toward both ends.

  When the secondary battery is charged and discharged in a heated state, the deterioration is promoted. In a battery module having a stacked body in which secondary batteries (square cells) are stacked, the temperature distribution in the stacking direction tends to increase as it approaches the center due to the heat generated by the battery accompanying charging and discharging. When such temperature variation occurs, the deterioration of some of the cells that have reached a high temperature is promoted, and the life of the battery module as a whole is shortened.

  Accordingly, the refrigerant is circulated through the refrigerant flow path of the first heat insulating material disposed between the cells, preferably while controlling the flow rate based on the outside air temperature or the like, thereby suppressing an increase in temperature due to heat generation of each cell. Then, the heat insulation of each 1st heat insulating material is enlarged as it goes to both ends from the center of a laminated body. As a result, it is possible to suppress the tendency for the battery closer to the end to dissipate heat and to have a low temperature, and to suppress variations in temperature inside the laminate.

  The aspect which changes the heat insulation of each 1st heat insulating material can be made into the aspect which the heat conductivity of each 1st heat insulating material becomes small gradually one by one as it goes to an end from a center. Or if the average of the thermal conductivity of several adjacent (for example, 3) 1st heat insulating materials is taken, the average value may become small gradually as it goes to an end from the center. Alternatively, all the first heat insulating materials are grouped so that several adjacent first heat insulating materials form one group, and the average value of the thermal conductivity of each group gradually increases from the center toward the end. It may be made smaller.

  Here, the preferable range of the thermal conductivity measured by JIS A 1412 of the 1st heat insulating material distribute | arranged to the both ends of a laminated body is 0.01-10 W / mK. A more preferable range of thermal conductivity is 0.2 to 2 W / mK. Here, the thermal conductivity is a value measured in an environment of normal temperature (25 ° C.).

  In the battery module according to one aspect of the present invention, a pair of second heat insulating materials are further disposed outside both ends in the stacking direction of the stacked body. The amount of heat conduction of the second heat insulating material is smaller than the amount of heat conduction of the first heat insulating material arranged at both ends of the laminate.

  The cells arranged at both ends of the laminate are easily cooled by the outside air. For this reason, in cold districts and the like, the temperature of the cells at both ends may be too low to supply sufficient power. Therefore, a second heat insulating material having a small amount of heat conduction, that is, a large heat insulating property, is arranged on the outer side of both ends of the laminated body to suppress the heat in and out through the both end faces of the laminated body. Thereby, it is prevented that the cell arrange | positioned at the both ends of a laminated body is cooled too much. In addition, the temperature difference between the cells arranged at both ends of the laminated body and the cells arranged at the center of the laminated body is suppressed by suppressing heat dissipation through both end surfaces of the laminated body of the cells arranged at both ends of the laminated body. Can be prevented from becoming large.

A battery module according to another embodiment of the present invention includes, among n (n ≧ 4) square cells, a heat dissipation coefficient K1 of the central square cell of the laminate, and a square shape disposed at both ends of the laminate. Ratio of the heat dissipation coefficient K2 of the cell: X (= K1 / K2), and among the (n-1) first heat insulating materials, the thermal conductivity κ1 of the first heat insulating material arranged at the center of the laminate The ratio of thermal conductivity κ2 of the first heat insulating material disposed at both ends of the laminate: Y (= κ1 / κ2)
0.8 ≦ X / Y ≦ 1.2 (1)
Meet the relationship.

Here, the heat dissipation coefficient K can be obtained as follows.
After heating a battery module composed of a plurality of rectangular cells and a heat insulating material having the same thermal conductivity, the battery module is installed in an environment of a predetermined temperature (Ta), and a predetermined flow rate of air is supplied to the refrigerant passage. The rate of change (dTb / dt) of the temperature (Tb) of each battery with respect to the time when cooling is performed by flowing through the battery. Further, the heat capacity (Mb) of the battery is measured. At this time, the following equation (2) holds.
(DTb / dt) = K (Tb−Ta) / Mb (2)

When the above equation (2) is integrated at time t, Tb = Ta + A · exp ((− K / Mb) t) is obtained (A is an integral constant), and from this, the following equation (3) is derived.
Ln (Tb-Ta) = Ln (A)-(K / Mb) t (3)

Then, when the change in the battery temperature is measured and plotted on a graph with Ln (Tb-Ta) on the vertical axis and time t on the horizontal axis, the heat dissipation coefficient K is expressed by the following equation (4) from the slope α of the graph. ).
K = α · Mb (4)

  By adjusting the thermal conductivity of each first heat insulating material so as to satisfy the relationship of the inequality (1), it is possible to effectively suppress variations in temperature inside the laminate.

  Here, the center cell of the laminate is one cell in the center if the number of cells is an odd number. If the number of cells is an even number, it is two cells near the center. The heat dissipation coefficient here is the amount of heat per unit time exchanged between the cell and the refrigerant. The 1st heat insulating material distribute | arranged to the center of a laminated body is one 1st heat insulating material of a center, if the number of cells is an even number. If the number of cells is an odd number, it is two first heat insulating materials near the center.

  Here, each of the pair of second heat insulating materials can be composed of a plurality of members. Many battery modules include end plates for restraining the laminate on the outside of both ends of the laminate. Moreover, the heat insulating material disposed between the cells is often disposed as an insulating spacer that insulates the cells from each other. Therefore, both end plates and spacers may be disposed at both ends of the laminate. For example, in such a case, the end plate and the spacer are the second heat insulating materials. When the end plate is singly disposed at both ends of the laminate, only the end plate is the second heat insulating material.

  In the battery module according to still another aspect of the present invention, the first heat insulating material is at least one selected from the group consisting of a resin, copper, aluminum, alumina, silica, boron nitride, silicon nitride, aluminum nitride, and carbon. And the filler has a thermal conductivity adjusted by the filler content. The resin includes GF-PET (glass fiber reinforced polyethylene terephthalate), PC (polycarbonate), PPS (polyphenyline sulfide), PP (polypropylene), PE (polyethylene), PA (polyamide), PBT (polybutylene terephthalate), ABS (acrylonitrile butaneethylene-styrene) or the like can be used.

  According to this structure, the heat insulation of each 1st heat insulating material can be adjusted only by adjusting content of the filler included in the material of a 1st heat insulating material. Therefore, since all the 1st heat insulating materials can be made into the same thickness, space efficiency can be improved. Here, the heat insulating property of the first heat insulating material can be adjusted in a wide range by adjusting the volume content of the filler in the range of 10 to 80%.

  In the battery module according to still another embodiment of the present invention, the first heat insulating material includes a foamed resin, and the thermal conductivity thereof is adjusted by the foaming ratio of the foamed resin. The foamed resin is a resin foamed with a foaming agent or the like, and may be a composition containing a filler or the like. As the resin, GF-PET, PC, PPS, PP, PE, PA, PBT, ABS, or the like can be used.

  According to this structure, the heat insulation of each 1st heat insulating material can be adjusted only by adjusting the foaming ratio of the foamed resin which is a material of a 1st heat insulating material. Therefore, since all the 1st heat insulating materials can be made into the same thickness, space efficiency can be improved.

  In the battery module according to still another embodiment of the present invention, the (n-1) first heat insulating materials are formed of the same material, each has a coolant channel, and from the center in the stacking direction of the stacked body. Each thickness is adjusted so that the amount of heat conduction becomes small as it goes to both ends.

  According to this structure, the heat insulation of each 1st heat insulating material can be adjusted only by changing the thickness of the 1st heat insulating material produced from the same material. Therefore, the procurement cost of the material can be reduced, and the cost can be reduced. In addition, the thermal insulation can be changed with a small change in thickness compared to the case of changing the width of the refrigerant passage in Patent Document 1. Therefore, a decrease in space efficiency can be suppressed as compared with Patent Document 1. In this case, the first heat insulating material may be GF-PET, PC, PPS, PP, PE, PA, PBT, ABS, or the like. Also in this case, it is preferable that the heat conduction amount of the second heat insulating material be smaller than the heat conduction amount of the first heat insulating material disposed at both ends of the laminate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a perspective view showing the external appearance of a battery module according to an embodiment of the present invention. FIG. 2 is a perspective view showing the internal structure of the battery module of FIG.
The battery module 10 includes a cell group 14 in which a predetermined number (10 in the illustrated example) of flat rectangular cells (secondary batteries) 12 are stacked in a row in the thickness direction. End plates 22 are arranged on the outer sides of both ends of the cell group 14 in the stacking direction.

  Each of the pair of end plates 22 has a substantially rectangular shape, and the four corners thereof are restrained by four rod-like restraining members 24 so as to hold the cell group 14 therebetween. The pair of long sides of the end plate 22 is parallel to the vertical direction of the cell 12 (the direction facing a sealing plate 36 described later and the bottom surface of the case 34). The pair of short sides of the end plate 22 is parallel to the width direction of the cell 12 (the direction perpendicular to the thickness direction and the vertical direction of the cell 12).

  Further, the pair of end plates 22 are connected by a bar-like connecting member 26 at the center of each of the pair of long sides. The ends of the cell group 14 in the vertical direction of the cell 12 are covered with cover plates 46 and 48, respectively.

  For the material of the restraining member 24, it is preferable to use a lightweight and high-strength engineering plastic such as GF-PET or PC. For the connecting member 26, for example, anodized aluminum can be used.

  FIG. 3 shows details of the restraining member. The restraining member 24 has ten cell engaging portions 24a arranged at an equal pitch in the axial direction. The four corners of the ten cells 12 are engaged with the cell engaging portions 24 a of the four restraining members 24, respectively, so that the ten cells 12 are brought into contact with the pair of end plates 22 by the four restraining members 24. Held between.

FIG. 4 is a perspective view showing a part of the cell group. FIG. 4 shows two adjacent cells 12 taken out from the cell group 14.
In the cell group 14, a spacer 30 for insulating the cells 12 from each other is disposed between two adjacent cells 12.

  The cell 12 is a secondary battery in which a power generation element (not shown) composed of a positive electrode, a negative electrode, and a separator interposed therebetween is housed in a metal battery case. Such secondary batteries include nickel metal hydride batteries and lithium ion batteries. In the case of a nickel metal hydride battery, nickel oxyhydroxide is used for the positive electrode, a hydrogen storage alloy is used for the negative electrode, and an aqueous potassium hydroxide solution is used for the electrolyte. In the case of a lithium ion battery, lithium cobalt oxide is used for the positive electrode and a carbon material such as graphite is used for the negative electrode.

  More specifically, the cell 12 includes a bottomed square case 34 having an opening at one end, and a sealing plate 36 that seals the opening. The case 34 and the sealing plate 36 are made of metal (for example, aluminum) and are electrically connected to each other. The case 34 is connected to the positive electrode of the power generation element, and the sealing plate 36 functions as the positive terminal of the cell 12 together with the case 34.

  On the surface of the sealing plate 36, a negative electrode terminal 38 connected to the negative electrode, a liquid injection port 40, and an explosion-proof valve 42 composed of a thin portion are provided. The sealing plate 36 and the negative electrode terminal 38 are insulated.

  The capacity of the cell 12 can be 3 Ah to 100 Ah. A more preferable range of the capacity of the cell 12 is 5 Ah to 30 Ah, and the present invention can be suitably applied to such a large secondary battery (for example, a lithium ion secondary battery).

  In the cell group 14, two adjacent cells 12 are stacked such that the sealing plate 36 provided with the negative electrode terminal 38 faces the same direction. Of the two adjacent cells 12, the positive terminal (sealing plate 36) of one cell 12 is connected to the negative terminal 38 of the other cell 12 by a connecting plate 44 made of a conductor. All the cells 12 of the cell group 14 are connected in series.

  In the cell group 14, the cell 12 at one end in the stacking direction of the cells 12 has the negative terminal 38 connected to the negative external terminal 52, and the cell 12 at the other end has the positive terminal (sealing plate 36) as the positive external terminal 54. Connected with.

  Next, the spacer 30 will be described. The spacer 30 has a thin plate shape, and has a corrugated plate portion 32 at least at a part thereof. The corrugated plate section 32 has a plurality of parallel groove-shaped refrigerant flow paths through which a refrigerant (for example, air) for cooling the cells 12 circulates. The refrigerant flow path is formed on both surfaces of the spacer 30 so as to have the same pitch and to be shifted by a half pitch between the surfaces. The cell 12 is in contact with the groove-shaped refrigerant flow path, and is cooled by the refrigerant flowing through the refrigerant flow path. As described above, the spacer 30 includes a cooling device that cools the cell 12.

  The refrigerant can be sent to the refrigerant flow path by a gas pump, a fan, or the like. At this time, the flow rate of the refrigerant is controlled by the control device based on the outside air temperature and the power consumption of a load device (for example, an electric vehicle) connected to the battery module so that each cell 12 can be appropriately cooled. Is preferred. Such a control device can be composed of a CPU (Central Processing Unit), an MPU (Micro Processing Unit) and a memory.

  Or when mounting the battery module 10 in a vehicle etc., you may send a refrigerant | coolant to a refrigerant | coolant flow path using the wind pressure applied to a traveling vehicle. Alternatively, the refrigerant can be sent to the refrigerant flow path by natural convection.

  Furthermore, in the battery module 10, the spacer 30 has a heat transfer adjustment function that adjusts heat transfer between the cells 12 so as to suppress variations in temperature inside the cell group 14. More specifically, each of the spacers 30 gradually decreases in heat conductivity (insulating properties gradually increases) from the center in the stacking direction of the cells 12 in the cell group 14 toward both ends. Hereinafter, this point will be described in detail.

  As shown in FIGS. 1 and 2, the spacer 30 can also be disposed on the outer side of the cells 12 at both ends in the stacking direction of the cell group 14. Hereinafter, the spacers 30 disposed between the cells 12 are referred to as inter-cell spacers (first heat insulating materials) in comparison with the spacers 30 disposed further outside the cells 12 at both ends. The spacers 30 arranged further outside the cells 12 at both ends are referred to as outer edge spacers.

  Here, an inter-cell spacer disposed in the center of the cell group 14 (one spacer 30 in the center if the number of cells 12 is an even number, and two near the center if the number of cells 12 is an odd number. The ratio of the thermal conductivity κ1 (unit: W / m · K) of the spacer 30) and the thermal conductivity κ2 of the inter-cell spacer closest to both ends of the cell group 14 is Y (= κ1 / κ2). Think.

  Further, the cells 12 arranged at the center of the cell group 14 (one cell 12 in the center if the number of cells 12 is odd, and two cells 12 near the center if the number of cells 12 is even) The ratio X: (K1 / K2) of the heat radiation coefficient K1 (unit: W / K) and the heat radiation coefficient K2 of the cells 12 at both ends of the cell group 14 is considered.

In the battery module 10, as described above, the heat insulating properties increase as the inter-cell spacers move from the center in the stacking direction of the cell group 14 toward both ends. At this time, by adjusting the thermal conductivity of each inter-cell spacer so as to satisfy the following inequality (1), it is possible to effectively suppress variations in temperature inside the cell group 14.
0.8 ≦ X / Y ≦ 1.2 (1)
At this time, it is preferable that the thermal conductivity measured by JIS A 1412 of the inter-cell spacers at both ends of the cell group 14 is 0.01 to 10 W / mK. A more preferable thermal conductivity is 0.2 to 2 W / mK.

  Furthermore, the heat insulation of the heat insulating material (henceforth edge heat insulating material) arrange | positioned at the both ends of the cell group 14 is considered. When there is an outer edge spacer, the end heat insulating material (second heat insulating material) includes the outer edge spacer and the end plate 22. In the absence of an outer edge spacer, the end insulation includes only the end plate 22. When the end heat insulating material includes only the end plate 22, the end plate 22 needs to be formed of an insulating member. Moreover, it is preferable to provide a refrigerant flow path for circulating a refrigerant for cooling the cells 12 on the surface of the end plate 22 facing the cell group 14.

  The thermal conductivity of the end heat insulating material is preferably smaller than the thermal conductivity of the inter-cell spacers at both ends of the cell group 14. Thus, by increasing the heat insulating property of the end heat insulating material, even in a cold region, it is possible to prevent the cells 12 at both ends from becoming too low temperature to obtain sufficient power. it can. Further, since the heat dissipation of the cells 12 arranged at both ends of the cell group 14 through the both end faces of the cell group 14 is suppressed, the cells 12 arranged at both ends of the cell group 14 are arranged at the center of the cell group 14. It is possible to prevent a large temperature difference from occurring with the cell 12 to be generated. Therefore, variations in temperature inside the cell group 14 can be suppressed.

  Examples of the material of the spacer 30 include resins such as GF-PET, PC, PPS, PP, PE, PA, PBT, and ABS, and copper, aluminum, alumina, silica, boron nitride, silicon nitride, aluminum nitride, and carbon. It is possible to use a mixture with a filler composed of or the like. By adjusting the filler content, the thermal conductivity of the spacer 30 (inter-cell spacer) can be adjusted. Here, the filler content can be adjusted within a range of 10 to 80%.

The thermal conductivity of the inter-cell spacer can also be adjusted by forming the spacer 30 from a foamed resin and adjusting the expansion ratio. According to this configuration, it is possible to adjust the thermal conductivity of each spacer and the heat insulating property of the heat insulating material only by adjusting the expansion ratio of the foamed resin of the material.
Therefore, since it is not necessary to change the thickness of the spacer, the space efficiency can be improved.

  The temperature between each cell can also be adjusted by forming all the inter-cell spacers from the same material and adjusting each thickness so that the amount of heat conduction decreases from the center in the stacking direction of the cell group 14 toward both ends. It is possible to suppress the variation of. According to this configuration, the amount of heat conduction of each spacer can be adjusted only by changing the thickness of the spacer manufactured from the same material. Therefore, the procurement cost of the material can be reduced, and the cost can be reduced.

  The power supply device of the present invention is suitably used for large-capacity and high-power applications such as electric vehicles and power sources for hybrid vehicles.

10 ... Battery module,
12 ... cell,
14 ... cell group,
34 ... Battery case 36 ... Sealing plate,
38 ... negative terminal,

Claims (11)

A battery module comprising a laminate in which n (n ≧ 4) rectangular cells and (n−1) first heat insulating materials are alternately laminated,
Each of the (n-1) first heat insulators has a refrigerant flow path, and the thermal conductivity measured by JIS A 1412 decreases from the center in the stacking direction of the stack toward both ends. The battery module.   The battery module of Claim 1 whose heat conductivity measured by JISA1412 of the 1st heat insulating material distribute | arranged to the both ends of a laminated body is 0.01-10W / mK. A pair of second heat insulating materials are further arranged outside both ends in the stacking direction of the stacked body,
The battery module according to claim 1 or 2, wherein a heat conduction amount of the second heat insulating material is smaller than a heat conduction amount of the first heat insulating material disposed at both ends of the laminate. Of the n (n ≧ 4) square cells, the ratio of the heat release coefficient of the central square cell of the laminate and the heat release coefficient of the square cells arranged at both ends of the laminate: X ,
Among the (n-1) first heat insulating materials, the heat conductivity of the first heat insulating material arranged at the center of the laminate and the heat conduction of the first heat insulating material arranged at both ends of the laminate. Ratio to rate: Y
0.8 ≦ X / Y ≦ 1.2
The battery module of any one of Claims 1-3 which satisfy | fills these relationships.   The battery module according to claim 1, wherein each of the pair of second heat insulating materials includes a plurality of members.   The first heat insulating material includes a resin and a filler including at least one selected from the group consisting of copper, aluminum, alumina, silica, boron nitride, silicon nitride, aluminum nitride, and carbon. The battery module according to claim 1, wherein the conductivity is adjusted by the filler content.   The battery module according to claim 6, wherein a volume content of the filler of the first heat insulating material is 10 to 80%.   The battery module according to any one of claims 1 to 5, wherein the first heat insulating material includes a foamed resin, and a thermal conductivity thereof is adjusted by a foaming ratio of the foamed resin.   The battery module according to claim 1, wherein the first heat insulating material has the same thickness in the stacking direction. A battery module comprising a laminate in which n (n ≧ 4) rectangular cells and (n−1) first heat insulating materials are alternately laminated,
The (n-1) first heat insulating materials are formed of the same material, each has a refrigerant flow path, and the amount of heat conduction decreases from the center in the stacking direction of the stacked body toward both ends. Each battery module is adjusted in thickness. A pair of second heat insulating materials are further arranged outside both ends in the stacking direction of the stacked body,
The battery module according to claim 10, wherein the heat conduction amount of the second heat insulating material is smaller than the heat conduction amount of the first heat insulating material arranged at both ends of the laminate.

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