Battery module

Abstract

A battery module 1 comprises: a plurality of battery cells 10; a cell holder 20 that holds the plurality of battery cells 10; a heat transfer body 4 that is stacked on the cell holder 20 and exchanges heat with the plurality of battery cells 10 or the cell holder 20; a heat pipe 5 that is provided on the heat transfer body 4 and has a protruding end 5a protruding from the cell holder 20; a heat sink 6 provided on the protruding end 5a; and a fan 7 for cooling the heat sink 6.

Description

Battery module

[0001] The present disclosure relates to a battery module.

[0002] Patent Document 1 discloses a battery module including a plurality of cylindrical battery cells and a heat plate for promoting heat dissipation from the battery cells.

[0003] Japanese Patent Translation of PCT No. 2023-540075

[0004] The heat plate only contacts one end of each battery cell. In this regard, there is room for improvement in enhancing the heat dissipation performance of the battery module.

[0005] An object of the present disclosure is to improve the heat dissipation performance of a battery module.

[0006] One aspect of the present disclosure provides a battery module including a plurality of battery cells, a cell holder for holding the plurality of battery cells, a heat transfer body laminated on the cell holder and configured to perform heat exchange with the plurality of battery cells or the cell holder, a heat pipe provided on the heat transfer body and having a protruding end portion protruding from the cell holder, a heat sink provided on the protruding end portion, and a fan for cooling the heat sink.

[0007] According to the present disclosure, the heat dissipation performance of the battery module can be improved.

[0008] An exploded perspective view of the battery module according to the first embodiment. A cross-sectional view of the battery module in Figure 1. An exploded perspective view of the battery assembly in Figure 1. A plan view of the battery assembly in Figure 1. An exploded perspective view of the heat transfer element, heat pipe, and heat sink in Figure 1. A schematic cross-sectional view of the heat pipe in Figure 1. A cross-sectional view of the battery module according to the second embodiment. An enlarged view of Figure 7. A cross-sectional view of the battery module according to the third embodiment. A cross-sectional view of the battery module according to the fourth embodiment. A cross-sectional view of the battery module according to the fifth embodiment. A perspective view of the battery assembly, heat transfer element, heat pipe, and heat sink in the battery module according to the sixth embodiment. A perspective view of the battery assembly, heat transfer element, heat pipe, and heat sink in the battery module according to the seventh embodiment. A perspective view of the battery assembly, heat transfer element, and heat pipe in the battery module according to the eighth embodiment. A perspective view of the battery assembly, heat transfer element, heat pipe, and heat sink in the battery module according to the ninth embodiment. A plan view of the battery assembly of the battery module according to the tenth embodiment.

[0009] A battery module according to one embodiment of the present disclosure comprises a plurality of battery cells, a cell holder for holding the plurality of battery cells, a heat transfer element stacked on the cell holder and performing heat exchange with the plurality of battery cells or the cell holder, a heat pipe provided on the heat transfer element having a protruding end that protrudes from the cell holder, a heat sink provided on the protruding end, and a fan for cooling the heat sink.

[0010] Here, a "heat pipe" is a long member containing a working fluid. Heat pipes are typically cylindrical, but may also be elliptical or flat. The working fluid is volatile, and the container containing the working fluid has high thermal conductivity. A high-temperature area exists around one end of the heat pipe, and a low-temperature area exists around the other end. Through phase transitions and circulation of the working fluid, heat is transferred from the high-temperature area to the low-temperature area via the heat pipe, thereby cooling the high-temperature area. The heat pipe repeats a cycle consisting of the following processes (a) to (d): (a) The liquid-phase working fluid is heated at one end of the heat pipe (high-temperature area), absorbing latent heat of vaporization and evaporating. (b) The gaseous-phase working fluid moves from one end of the heat pipe to the other end. (c) The gaseous-phase working fluid is cooled at the other end of the heat pipe (low-temperature area), releasing latent heat of condensation and condensing. (d) The liquid-phase working fluid moves from the other end of the heat pipe to the one end.

[0011] According to the above configuration, the heat transfer element absorbs the heat generated by the battery cells either directly or through the cell holder. A heat pipe is provided on this heat transfer element, while the end of the heat pipe protrudes from the cell holder, and a heat sink is provided on this protruding end. Through the above cycle, the heat pipe transfers the heat from the heat transfer element, which is the high-temperature part, to the heat sink, which is the low-temperature part. The heat sink is cooled by a fan, thereby allowing it to continue functioning as the low-temperature part. In this way, the heat generated by the battery cells can be continuously released to the outside of the cell holder via the heat transfer element and heat pipe, improving the heat dissipation performance of the battery module.

[0012] In a battery module according to another embodiment of the present disclosure, the heat transfer element may include a thermal interface material laminated on a cell holder and a plate laminated on the thermal interface material.

[0013] According to the above configuration, the heat transfer element has a two-layer structure consisting of a thermal interface material (TIM) and a plate. The heat generated by the battery cell is efficiently released to the plate via the TIM.

[0014] In a battery module according to another embodiment of the present disclosure, a plurality of battery cells constitute a plurality of parallel units, each of which consists of two or more battery cells connected in parallel to one another, the plurality of parallel units are connected sequentially in series, and the cell holder includes a holder frame made of an insulating material and provided with a plurality of block housing sections, and a plurality of blocks each housed in the plurality of block housing sections, the blocks being made of a material having higher thermal conductivity than the insulating material and having two or more cell housing sections for each housing two or more battery cells constituting a set of parallel units, and a thermal interface material which is insulating and may cover the plurality of blocks.

[0015] In the above configuration, the battery cells are housed in the cell housings of the blocks, and the heat transfer materials are stacked on the cell holder so as to cover multiple blocks. Because the blocks have high thermal conductivity, the heat generated by the battery cells is efficiently conducted to the heat transfer materials through the blocks.

[0016] Each block holds two or more battery cells that constitute a single parallel unit, and multiple blocks are each housed in block housings of a holder frame made of insulating material. Therefore, even if the battery cells have polarity on the side facing the block, and even if the block has both high thermal conductivity and electrical conductivity, it is possible to prevent different parallel units from being undesirably electrically connected within the cell holder.

[0017] The thermal interface material covers multiple blocks, thereby improving heat dissipation and reducing the number of parts. The thermal interface material is insulating. Therefore, even if the blocks have high thermal conductivity and electrical conductivity, it is possible to prevent undesirable electrical connections between different parallel units via the heat transfer material. In addition, the plates and heat pipes are electrically insulated from the blocks by the thermal interface material. Even if conductive materials are used for the heat pipes, this also prevents undesirable electrical connections from occurring.

[0018] In a battery module according to another embodiment of the present disclosure, the heat pipe has a container portion that encloses a working fluid, and the container portion may be in the shape of a plate.

[0019] With the above configuration, the area over which the heat pipe can exchange heat with the heat transfer element is widened, improving heat dissipation. In addition, it is easier to equalize the amount of heat absorbed from multiple battery cells, and temperature variations between battery cells can be suppressed.

[0020] Other embodiments of the present disclosure may further include a Peltier element interposed between a protruding end and a heat sink.

[0021] With the above configuration, the protruding end can be actively cooled by the Peltier element, the heat pipe can more reliably execute the above cycle, and heat dissipation is improved.

[0022] In a battery module according to another embodiment of the present disclosure, the Peltier element includes a first plate material that contacts a heat pipe and a second plate material that contacts a heat sink, and the applied state of the Peltier element may be switched between a first applied state in which the first plate material becomes a heat-absorbing part and the second plate material becomes a heat-generating part, and a second applied state in which the first plate material becomes a heat-generating part and the second plate material becomes a heat-absorbing part.

[0023] With the above configuration, in the first applied state, the Peltier element can function as a low-temperature element relative to the heat pipe, promoting the cooling of the battery cell. On the other hand, in the second applied state, the Peltier element can function as a high-temperature element relative to the heat pipe, promoting the heating of the battery cell. For example, in cold regions, immediately after the battery module is started up, the temperature of the battery cell may be excessively low due to the influence of ambient temperature. In such cases, the temperature of the battery cell can be quickly raised to an appropriate temperature.

[0024] The following describes specific examples of this disclosure in detail based on the drawings. In the following description, terms indicating specific directions or positions (e.g., "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating understanding of the disclosure with reference to the drawings, and the meaning of these terms does not limit the technical scope of this disclosure. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments shown below are examples of the technical concept of this disclosure and do not limit this disclosure to them. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are intended to be illustrative, and not to limit the scope of this disclosure unless specifically stated. Also, the content described in one embodiment or example is applicable to other embodiments or examples. Furthermore, the size and positional relationships of the components shown in the drawings may be exaggerated for clarity in the explanation.

[0025] The battery module of this disclosure is applicable, for example, to emergency power sources such as battery backup units (BBUs) or to power the drive motors of electric vehicles. However, this disclosure does not specify the application of the battery module, and it can be used as a power source for various other electrical devices.

[0026] (First Embodiment) Referring to Figures 1 and 2, the battery module 1 according to the first embodiment comprises an outer case 2, a battery assembly 3, a heat transfer element 4, a heat pipe 5, a heat sink 6, and a fan 7.

[0027] The outer casing 2 is made of an insulating material. The outer casing 2 defines an internal space 2a in which the battery assembly 3, heat transfer element 4, heat pipe 5, heat sink 6, and fan 7 are housed.

[0028] The outer casing 2 is, for example, a long rectangular parallelepiped and has a bottom wall 2b, a top wall 2c, a pair of side walls 2d, a first end wall 2e, and a second end wall 2f. The bottom wall 2b and the top wall 2c are separated from each other in the vertical direction (height direction Z of the outer casing 2), and in plan view (i.e., viewed in the height direction Z), it is a long, narrow rectangle. Hereinafter, the direction in which the long side of the rectangle extends will be referred to as the "longitudinal direction X," and the direction in which the short side extends will be referred to as the "width direction Y." The longitudinal direction X, the width direction Y, and the height direction Z are each perpendicular to the other two directions.

[0029] The bottom wall 2b and the top wall 2c extend in the longitudinal direction X and the width direction Y. The pair of side walls 2d are separated from each other in the width direction Y, extend in the longitudinal direction X and the height direction Z, and connect the long edges of the bottom wall 2b and the top wall 2c. The first end wall 2e extends in the width direction Y and the height direction Z, and connects the short edges of the bottom wall 2b and the top wall 2c at one end in the longitudinal direction X (lower left side of Figure 1). The second end wall 2f extends in the width direction Y and the height direction Z, and connects the short edges of the bottom wall 2b and the top wall 2c at the other end in the longitudinal direction X (upper right side of Figure 1). The first end wall 2e and the second end wall 2f are provided with ventilation openings 2g and 2h, respectively. The internal space 2a communicates with the outside of the outer case 2 via the ventilation openings 2g and 2h.

[0030] The outer casing 2 has a base 2A and a cover 2B that are separable from each other in the height direction Z. The base 2A includes a bottom wall 2b, a first end wall 2e, and a second end wall 2f, and its longitudinal section (cross-section viewed in the width direction Y as shown in Figure 2) is U-shaped. The cover 2B includes a top wall 2c and a pair of side walls 2d, and its cross-section (cross-section viewed in the longitudinal direction X) is inverted U-shaped. The cover 2B is placed over the base 2A from above and fastened to the base 2A.

[0031] The battery assembly 3, heat transfer element 4, and heat pipe 5 are arranged in this order from bottom to top. The heat pipe 5 is elongated in the longitudinal direction X. The heat pipe 5 has a protruding end 5a that projects from the battery assembly 3 to one side in the longitudinal direction X. The heat sink 6 is provided at the protruding end 5a and protrudes downward from the heat pipe 5. The battery assembly 3 and the heat sink 6 are adjacent in the longitudinal direction X below the heat pipe 5 in the internal space 2a of the outer casing 2.

[0032] The fan 7 is installed on the inner surface of the bottom wall 2b. The fan 7 forms an airflow in the longitudinal direction X (see the black arrow in Figure 2) in order to forcibly cool the components of the battery module 1, including the heat sink 6, within the internal space 2a.

[0033] In this embodiment, while the fan 7 is operating, air from outside the outer case 2 flows into the internal space 2a through the vent 2g in the first end wall 2e. In the internal space 2a, the air flows from one side to the other in the longitudinal direction X. During this process, the components of the battery module 1 are cooled by air, while the air is heated by heat exchange with the components. This air then flows out of the internal space 2a to the outside of the outer case 2 through the vent 2h in the second end wall 2f.

[0034] In this embodiment, the battery assembly 3, heat transfer element 4, heat pipe 5, and heat sink 6 are arranged between the first end wall 2e and the fan 7. The protruding end 5a protrudes from the battery assembly 3 to the other side in the longitudinal direction X (downstream side of the airflow). Accordingly, the heat sink 6 is positioned on the other side in the longitudinal direction X (downstream side of the airflow) relative to the battery assembly 3.

[0035] As shown in Figures 1 to 4, the battery assembly 3 includes a plurality of battery cells 10, a cell holder 20 that holds the plurality of battery cells 10, and a current collection structure 30 that electrically connects the plurality of battery cells 10 held in the cell holder 20.

[0036] Referring to Figure 3, the battery cell 10 is a cylindrical lithium-ion secondary battery. However, the battery cell 10 may be a battery other than a cylindrical type, such as a prismatic battery, or it may be a battery other than a lithium-ion secondary battery, such as an all-solid-state battery.

[0037] The battery cell 10 has a first end face portion 11, a second end face portion 12, and a side portion 13, and the battery cell 10 is elongated in the axial direction. The first end face portion 11 and the second end face portion 12 face each other in the cell length direction (axial direction). The side portion 13 connects the periphery of the first end face portion 11 to the periphery of the second end face portion 12. The first end face portion 11 and the second end face portion 12 are circular when viewed in the axial direction. The side portion 13 has a circular cross-section, and its outer diameter is constant in the axial direction.

[0038] The battery cell 10 has a peripheral electrode 14 provided on the periphery of the first end face portion 11, and a central electrode 15 provided in the center of the first end face portion 11. The peripheral electrode 14 and the central electrode 15 have opposite polarities. For example, the peripheral electrode 14 is the negative electrode and the central electrode 15 is the positive electrode, but the polarities may be reversed.

[0039] The battery cell 10 has a bottomed cylindrical outer casing 16 that houses the electrode body and electrolyte, and a sealing plate 17 that closes the opening of the outer casing 16. The outer casing 16 and the sealing plate 17 are made of a conductive material. The sealing plate 17 is attached to the outer casing 16 via an insulating material (not shown). The sealing plate 17 forms the center of the first end face portion 11, i.e., the central electrode 15. The outer casing 16 forms the periphery of the first end face portion 11, i.e., the peripheral electrode 14. The outer casing 16 also forms a side portion 13 and a second end face portion 12 along with the periphery of the first end face portion 11. The side portion 13 and the second end face portion 12 are electrically connected to the peripheral electrode 14 and have the same polarity as the peripheral electrode 14.

[0040] Multiple battery cells 10 are held in a cell holder 20 in a vertical orientation (with the cell length direction facing the height direction Z) with their heights aligned. In this embodiment, all battery cells 10 have their first end faces 11 facing downwards. Multiple battery cells 10 form multiple cell rows 18 aligned in the longitudinal direction X, and the multiple cell rows 18 are arranged in a staggered pattern. In each cell row 18, multiple battery cells 10 are arranged in the width direction Y. This arrangement of battery cells 10 is realized by the cell holder 20.

[0041] Multiple battery cells 10 constitute multiple parallel units 19. In each parallel unit 19, two or more battery cells 10 are connected in parallel to each other. Multiple parallel units 19 are sequentially connected in series. This electrical connection between the battery cells 10 is realized by a current collection structure 30 (see Figures 1 and 2).

[0042] The cell holder 20 includes a holder frame 21 provided with a plurality of block housing sections 22, and a plurality of blocks 23 that are individually housed in the plurality of block housing sections 22.

[0043] The holder frame 21 is made of an insulating material such as synthetic resin, and has a long harmonica shape in the longitudinal direction X. The holder frame 21 includes a rectangular bottom wall 21a, a pair of side walls 21b that stand up from the bottom wall 21a and face each other in the width direction Y and extend in the longitudinal direction X, a pair of end walls 21c and 21d provided at both ends in the longitudinal direction X, and a plurality of partition walls 21e provided at intervals in the longitudinal direction X between the pair of end walls 21c and 21d. The pair of end walls 21c and 21d and the plurality of partition walls 21e stand up from the bottom wall 21a and connect the pair of side walls 21b to each other in the width direction Y.

[0044] The space surrounded by the bottom wall 21a, the pair of side walls 21b, and the pair of end walls 21c and 21d is partitioned by a plurality of partition walls 21e into a plurality of spaces arranged in the longitudinal direction X. These spaces are open upward. The plurality of block accommodating portions 22 correspond to the plurality of spaces thus partitioned respectively and are arranged in the longitudinal direction X. The number of partition walls 21e is one less than the number of block accommodating portions 22, and the numbers of the block accommodating portions 22 and the blocks 23 correspond to the number of parallel units 19.

[0045] The block accommodating portion 22 is constituted by the bottom wall 21a and the pair of side walls 21b. Also, one block accommodating portion 22 is constituted by two adjacent walls among the end walls 21c, 21d, and the partition walls 21e. Hereinafter, for convenience of explanation, these two walls are referred to as "opposing walls 22a and 22b". The end wall 21c serves as the opposing wall 22a of the block accommodating portion 22 at one end on the longitudinal direction X side. The end wall 21d serves as the opposing wall 22b of the block accommodating portion 22 at the other end on the longitudinal direction X side. Each partition wall 21e serves as the opposing wall 22a of the block accommodating portion 22 corresponding to the space on the other side in the longitudinal direction X as seen from itself and the opposing wall 22b of the block accommodating portion 22 corresponding to the space on the one side in the longitudinal direction X as seen from itself.

[0046] The block 23 is made of a material having higher thermal conductivity than the holder frame 21. Examples of such a material include metal materials such as aluminum alloys. When a metal material is applied, the block 23 also has conductivity.

[0047] Block 23 is generally in the shape of a rectangular parallelepiped, and has a bottom surface 23a, a top surface 23b, and a pair of side surfaces 23c and 23d facing in the longitudinal direction X. The block 23 is fitted into the corresponding block housing portion 22 from above. The bottom surface 23a is supported by the bottom wall 21a of the holder frame 21. The pair of side surfaces 23c and 23d face the opposing walls 22a and 22b respectively. The top surface 23b faces upward and is exposed.

[0048] One block 23 constitutes two or more cell housing portions 25 alone or in cooperation with the opposing walls 22a and 22b of the block housing portion 22 corresponding to itself. In each cell housing portion 25 of the block 23, the battery cells 10 constituting the parallel unit 19 corresponding to itself are individually housed.

[0049] Referring to FIG. 1, in the present embodiment, as a mere example, the battery assembly 3 has 45 battery cells 10. The 45 battery cells 10 constitute 5 parallel units 19, and 9 battery cells 10 constitute 1 parallel unit 19. The 45 battery cells 10 form 15 rows of cell rows 18, and 3 battery cells 10 form 1 row of cell rows 18.

[0050] According to the above example, there are 5 block housing portions 22 and 5 blocks 23, and 4 partition walls 21e. Each block 23 constitutes 9 cell housing portions 25. The 9 cell housing portions 25 are arranged in 3 rows arranged in the longitudinal direction X, and 3 cell housing portions 25 are arranged in the width direction Y in each row.

[0051] Referring to FIGS. 3 and 4, regarding each block 23, the three cell housing portions 25 forming a column at the center in the longitudinal direction X are constituted by three through holes 26 penetrating the block 23 in the height direction Z. The through holes 26 are circular in plan view and form the entire circumference of the cell housing portion 25.

[0052] Regarding the three cell housing sections 25 arranged in a row on one side in the longitudinal direction X (lower left side of the paper in Figure 3), three block grooves 27a are recessed in the side surface 23c of the block 23. Each block groove 27a extends in the height direction Z from the top surface 23b to the bottom surface 23a and is semicircular in plan view. On the other hand, three frame grooves 27b are recessed in the opposing wall 22a at positions opposite to the three block grooves 27a. Each frame groove 27b extends in the height direction Z from the upper end to the lower end of the opposing wall 22a and is semicircular in plan view. When the block 23 is housed in the block housing section 22, the block grooves 27a become continuous with the frame grooves 27b, thereby forming the cell housing section 25.

[0053] The same applies to the three cell housing sections 25 that form a row on the other side in the longitudinal direction X (upper right side of the paper in Figure 3). Three block grooves 28a are recessed in the side surface 23d of the block 23, and three frame grooves 28b are recessed in the opposing wall 22b. The block grooves 28a work together with the frame grooves 28b to form the cell housing section 25.

[0054] Each cell housing portion 25 is a bottomed cylindrical shape, closed off by the bottom wall 21a of the holder frame 21 and open upwards. The battery cell 10 is fitted into the cell housing portion 25 from above with its first end face portion 11 facing downwards. Insertion stops when the first end face portion 11 abuts against the bottom wall 21a. The second end face portion 12 is exposed with its face upwards. The side portion 13 is in thermal contact with the inner circumferential surface of the cell housing portion 25. "Thermal contact" includes not only cases where the side portion 13 is in direct contact with the inner circumferential surface of the cell housing portion 25, but also cases where heat can be transferred between the side portion 13 and the block 23 via the resin filled in the gap between the side portion 13 and the inner circumferential surface of the cell housing portion 25.

[0055] Referring to Figure 1, in this embodiment, the current collection structure 30 is a so-called one-sided current collection structure, in which the current collection structure is concentrated on one side of the battery cell 10 and cell holder 20 in the height direction Z. The current collection structure 30 is located below the cell holder 20. In contrast, the heat transfer element 4 is located on the opposite side of the current collection structure 30 in the height direction Z, that is, above the cell holder 20.

[0056] The current collection structure 30 includes a first current collector group 31, an insulating layer 32, and a second current collector group 33. The first current collector group 31, the insulating layer 32, and the second current collector group 33 are arranged in this order from the lower surface of the bottom wall 21a of the holder frame 21 downwards.

[0057] The first current collector group 31 consists of the same number of first current collector plates 31A as the number of parallel units 19, and the second current collector group 33 consists of the same number of second current collector plates 33A as the number of parallel units 19. Both the first current collector plates 31A and the second current collector plates 33A are arranged in the longitudinal direction X. One first current collector plate 31A covers one parallel unit 19 from below. One second current collector plate 33A covers one first current collector plate 31A and, consequently, one parallel unit 19 from below.

[0058] Referring to Figure 2, the bottom wall 21a is provided with multiple openings 21f that open up each of the multiple cell housings 25. The first end face portion 11 cannot pass through the openings 21f and abuts against the bottom wall 21a, while the peripheral electrode 14 and the central electrode 15 are exposed downwards through the openings 21f.

[0059] The first current collector plate 31A is electrically connected to the peripheral electrode 14 of the corresponding parallel unit 19 through the opening 21f. The second current collector plate 33A is electrically connected to the central electrode 15 of the corresponding parallel unit 19 through the through hole in the insulating layer 32, the through hole in the first current collector plate 31A, and the opening 21f. As a result, two or more battery cells 10 are connected in parallel between the first current collector plate 31A and the second current collector plate 33A within each parallel unit 19. Furthermore, the second current collector plate 33A is electrically connected to the first current collector plate 31A adjacent to it in the longitudinal direction X. As a result, multiple parallel units 19 are sequentially connected in series.

[0060] Referring to Figures 2 and 5, the heat transfer body 4 includes a thermal interface material 41 laminated on the cell holder 20 and a plate 42 laminated on the thermal interface material 41.

[0061] The thermal interface material 41 is installed on the upper surface of the battery assembly 3. The upper surface of the battery assembly 3 includes three types of surfaces: the upper surface 21g of the holder frame 21, the top surface 23b of the block 23, and the outer surface of the second end face portion 12 of the battery cell 10. The upper surface 21g of the holder frame 21 corresponds to a seamless continuity of the upper surfaces of the pair of side walls 21b, the upper surfaces of the pair of end walls 21c and 21d, and the upper surfaces of the multiple partition walls 21e. The height positions of the three types of surfaces are not necessarily aligned, and the upper surface of the battery assembly 3 may have irregularities. For example, the upper surface 21g may be located higher than the other two types of surfaces, thereby improving the insulation between the parallel units 19.

[0062] The thermal interface material 41 is made of, for example, a silicon-based material containing a thermally conductive filler. The thermal interface material 41 has not only high thermal conductivity but also flexibility. Therefore, when the thermal interface material 41 is placed on the upper surface of the battery assembly 3, the lower surface of the thermal interface material 41 can be made to adhere closely to any of the three types of surfaces, regardless of the irregularities of the upper surface.

[0063] The thermal interface material 41 is rectangular in shape, complementary to or substantially congruent to the battery assembly 3 in a plan view. The peripheral edge of the thermal interface material 41 is laminated on the upper surface 21g of the holder frame 21. The thermal interface material 41 covers substantially the entire upper surface of the battery assembly 3 without protruding from the cell holder 20.

[0064] Here, the peripheral electrodes 14 of the battery cell 10 are electrically connected to the side portion 13 and the second end portion 12. The block 23 can directly contact the side portion 13 in the cell housing portion 25. If the block 23 is made of a conductive material, the peripheral electrodes 14 are also electrically connected to the block 23. Within the cell holder 20, multiple blocks 23 are insulated from each other by partition walls 21e. This prevents different parallel units 19 from being undesirably electrically connected within the cell holder 20.

[0065] The thermal interface material 41 also has insulating properties. Therefore, even if the thermal interface material 41 covers the top surface 23b of all blocks 23 and the second end surface portion 12 of all battery cells 10 at once, it is possible to prevent different parallel units 19 from being undesirably electrically connected via the thermal interface material 41.

[0066] Furthermore, even if a conductive member (for example, a plate 42 or a heat pipe 5) is installed on the upper side of the thermal interface material 41, this conductive member is insulated from the battery cell 10 and block 23 by the thermal interface material 41. Therefore, it is possible to prevent different parallel units 19 from being undesirably electrically connected through this conductive member.

[0067] The plate 42 is made of a material with high thermal conductivity and is in the form of a plate. Examples of such materials include metallic materials such as aluminum alloys. When a metallic material is used, the plate 42 also has electrical conductivity.

[0068] Like the thermal interface material 41, the plate 42 is rectangular in shape, complementary to or substantially congruent to the battery assembly 3 in a plan view. The peripheral edge of the plate 42 is stacked on the upper surface 21g of the holder frame 21. The upper surface 21g of the holder frame 21 is provided with female screw holes 21h. A bolt 71 is inserted from above through the peripheral edge of the plate 42 and screwed into the female screw holes 21h, thereby screwing the plate 42 onto the holder frame 21. At this time, the thermal interface material 41 is sandwiched between the plate 42 and the battery assembly 3, and is in close contact with the upper surface of the battery assembly 3 and the lower surface of the plate 42.

[0069] Referring to Figures 1 and 5, in this embodiment, the heat pipe 5 is separate from the heat transfer element 4 (particularly the plate 42). Two heat pipes 5 are provided so as to be stacked on top of the heat transfer element 4. The heat pipe 5 has a flat appearance and is rectangular in plan view. The heat pipe 5 is placed on top of the upper surface of the plate 42 with its longer side facing the longitudinal direction X.

[0070] The plate 42 has two pipe fixing grooves 42a on its upper surface, each housing two heat pipes 5. The two pipe fixing grooves 42a extend parallel to the longitudinal direction X and are open at both ends in the longitudinal direction X. The plate 42 has three ridges 42b on its upper surface that extend in the longitudinal direction X to define the two pipe fixing grooves 42a. The three ridges 42b are divided into three locations in the width direction Y: the center and both ends, and protrude upward relative to the bottom surface of the pipe fixing grooves 42a. The aforementioned bolts 71 are inserted through holes 42c provided in the ridges 42b at both ends.

[0071] The heat pipe 5 is received in the pipe fixing groove 42a by aligning one end of the heat pipe 5 in the longitudinal direction X with one end of the plate 42 in the longitudinal direction X. The length of the heat transfer element 4 (dimension in the longitudinal direction X) is approximately the same as the length of the battery assembly 3, and the heat pipe 5 is longer than both the battery assembly 3 and the heat transfer element 4. The heat pipe 5 protrudes from the battery assembly 3 and the heat transfer element 4 on the other side in the longitudinal direction X.

[0072] The other end of the heat pipe 5 is a protruding end 5a that is separated from the battery assembly 3. One end of the heat pipe 5 is a base end 5b that overlaps with the battery assembly 3 in the height direction Z. In principle, due to the heat generated by the battery cell 10, the area around the base end 5b becomes relatively hot, while the area around the protruding end 5a becomes relatively cold. (For a case where the area around the protruding end 5a is intentionally made hot, refer to the second embodiment.)

[0073] Referring to Figure 6, the heat pipe 5 mainly consists of a container portion 51 and a working fluid 52 sealed within the container portion 51. The container portion 51 forms the external appearance of the heat pipe 5 and defines a sealed space in which the working fluid 52 is contained.

[0074] The container portion 51 is made of a material with high thermal conductivity. Examples of such materials include metallic materials such as pure copper or copper alloys. The working fluid 52 is volatile, and a material appropriate to the operating temperature environment of the heat pipe 5 is appropriately selected.

[0075] At the end exposed to the high-temperature area (base end 5b), the working fluid 52 evaporates due to the heat absorbed from the high-temperature area. At the end exposed to the low-temperature area (protruding end 5a), the working fluid 52 condenses by releasing heat to the low-temperature area. The working fluid 52 that evaporated at the base end 5b moves toward the protruding end 5a. The working fluid 52 that condensed at the protruding end 5a moves toward the base end 5b. In this way, by causing the working fluid 52 to undergo a phase transition and circulate within the container portion 51, cooling of the high-temperature area is promoted.

[0076] In the operating state of the battery module 1, the height direction Z is oriented vertically, and the heat pipe 5 may extend horizontally. In this case, the heat pipe 5 may have a wick (not shown) provided inside the container portion 51. This allows the liquid-phase working fluid 52 to move horizontally by capillary action.

[0077] Referring to Figures 2 and 5, the heat sink 6, as an example, has a comb-shaped cross-section. The heat sink 6 has a base plate 61 and a plurality of plate-shaped fins 62 protruding from the base plate 61. The plurality of fins 62 protrude from the base plate 61 on the same side and are arranged parallel to each other with spacing between them.

[0078] The heatsink 6 is fixed to the protruding end 5a of the heat pipe 5. The base plate 61 is fixed to the heat pipe 5 in a horizontal position, and the multiple fins 62 protrude downward from the base plate 61 and are arranged in the width direction Y. As a result, the airflow in the longitudinal direction X is not obstructed by the heatsink 6 and can pass through the space between the fins 62. Furthermore, both the battery assembly 3 and the heatsink 6 are positioned below the heat pipe 5. The internal structure of the outer case 2 is compact in the height direction Z, contributing to the low profile of the battery module 1.

[0079] The method of assembling the heat pipe 5 and the heat sink 6 is not particularly limited. For example, in the above mounting position, the heat sink 6 has a slot 63 that penetrates the base plate 61 in the longitudinal direction X. The protruding end 5a of the heat pipe 5 is inserted through the slot 63. The base plate 61 includes an upper wall portion 61a and a lower wall portion 61b that surround the slot 63. The fins 62 protrude downward from the lower wall portion 61b, while a plurality of female threads 64 penetrate the upper wall portion 61a. With the heat pipe 5 inserted through the slot 63, the male thread 72 is screwed into the female thread 64 from above. The heat pipe 5 is pressed downward by the tip of the male thread 72 and comes into close contact with the lower wall portion 61b.

[0080] In the illustrated example, two heatsinks 6 are provided on each of the two heat pipes 5. This is just one example; the two heat pipes 5 may also be attached to a single heatsink 6.

[0081] Referring to Figure 2, when the battery module 1 is used as described above, the battery cell 10 generates heat. Some of the heat is transferred from the second end face portion 12 to the heat transfer element 4. In addition, some of the heat is transferred from the side portion 13 to the block 23, and then from the top surface 23b of the block 23 to the heat transfer element 4.

[0082] The surface area of ​​the side portion 13 is larger than that of the second end portion 12. Therefore, compared to a configuration in which the heat transfer element 4 is in contact only with the second end portion 12, the heat dissipation from the battery cell 10 is improved. The block 23 has higher thermal conductivity than the holder frame 21. Therefore, compared to a configuration in which the portion corresponding to the holder frame 21 and the portion corresponding to the block 23 are integrated with an insulating material and the side portion 13 is in contact with the insulating material, the heat dissipation from the battery cell 10 is improved.

[0083] The heat transfer element 4 covers almost the entire upper surface of the battery assembly 3. Therefore, the volume of the heat transfer element 4 is large, and the amount of heat dissipated from the battery assembly 3 to the heat transfer element 4 is large. The lower surface of the heat transfer element 4 (the lower surface of the thermal interface material 41) is in close contact with the upper surface of the battery assembly 3, regardless of any irregularities on the upper surface. Therefore, the heat transfer element 4 can absorb heat evenly from the entire surface of the battery assembly 3, and temperature variations between the battery cells 10 can be suppressed. In this way, both the average and variance values ​​of the temperature of the battery cells 10 are reduced.

[0084] The heat transferred to the heat transfer element 4 is transferred via the heat pipe 5. The heat pipe 5 has a protruding end 5a that extends from the cell holder 20, and the protruding end 5a is separated from the battery assembly 3 and the heat transfer element 4. Therefore, from the perspective of the heat pipe 5, the environment around the protruding end 5a is easily kept cooler than the environment around the base end 5b which is stacked on the heat transfer element 4. The area around the base end 5b functions as a high-temperature area, and the area around the protruding end 5a functions as a low-temperature area. The heat pipe 5 is used to effectively transfer the heat from the heat transfer element 4 to the outside of the cell holder 20.

[0085] The heat pipe 5 is positioned to cover almost the entire surface of the heat transfer element 4. As a result, the amount of heat absorbed by the heat pipe 5 is increased, and heat is evenly transferred from the upper surface of the heat transfer element 4 (the upper surface of the plate 42) to the heat pipe 5.

[0086] The heat pipe 5 is plate-shaped. This allows for both broad coverage of the upper surface of the heat transfer element 4 and keeping the height of the battery module 1 low.

[0087] The heat transferred to the protruding end 5a is released to the heat sink 6. This promotes the condensation of the working fluid 52 at the protruding end 5a, enabling efficient heat transfer by the heat pipe 5 and subsequent cooling of the high-temperature part.

[0088] The heatsink 6 is forcibly cooled by the fan 7. The heat transferred to the heatsink 6 is released, allowing the heatsink 6 to continue functioning as a low-temperature area. Therefore, the battery assembly 3 can be continuously cooled while the battery module 1 is in operation.

[0089] The airflow formed by the fan 7 passes around the battery assembly 3 before passing through the heatsink 6. This allows the battery assembly 3 to be cooled with cooler air, further improving its heat dissipation. Although the air that has exchanged heat with the battery assembly 3 is blown onto the heatsink 6, this air also allows for sufficient heat dissipation from the heatsink 6.

[0090] The air that has passed through the heat sink 6 flows out of the outer casing 2 through the vent 2h. Another heat-generating component 8 may be placed in the internal space 2a, downstream of the airflow relative to the heat sink 6. A printed circuit board can be an example of such a heat-generating component 8. The heat-generating component 8, such as the circuit board, can be air-cooled, contributing to the stable operation of the battery module 1.

[0091] (Second Embodiment) Next, with reference to Figures 7 and 8, the battery module 1 according to the second embodiment will be described, focusing on the differences from the above embodiment.

[0092] The battery module 1 according to this embodiment includes a Peltier element 9 interposed between the protruding end 5a of the heat pipe 5 and the heat sink 6. The Peltier element 9 is flat overall.

[0093] Referring to Figure 8, the Peltier element 9 includes a first plate material 91 that contacts the lower surface of the protruding end 5a, a second plate material 92 that contacts the upper surface of the base plate 61 of the heat sink 6, and a joint portion 93 interposed between the first plate material 91 and the second plate material 92 to connect the plates. When a DC current is passed through the joint portion 93, heat is transferred from one of the first plate material 91 and the second plate material 92 to the other. The plate material that is the source of the heat transfer functions as a heat-absorbing part. The plate material that is the destination of the heat transfer functions as a heat-generating part.

[0094] Hereinafter, the state in which a direct current flows through the junction 93 is referred to as the "applied state" of the Peltier element 9. The applied state includes a first applied state and a second applied state in which the polarity of the current is reversed from that of the first applied state. The Peltier element 9 is configured to be switchable between the first applied state and the second applied state. Reversing the polarity of the current reverses the direction of heat transfer.

[0095] In the first applied state, heat is transferred from the first plate material 91 to the second plate material 92. The first plate material 91 functions as a heat-absorbing part, and the second plate material 92 functions as a heat-generating part. The Peltier element 9 acts as a cooler for the protruding end 5a.

[0096] As a result, the protruding end 5a in contact with the first plate material 91 is actively cooled by the Peltier element 9. Heat transfer from the base end 5b of the heat pipe 5 to the protruding end 5a is effectively performed, further improving the heat dissipation performance of the battery module 1.

[0097] In the second applied state, contrary to the first applied state, heat moves from the second plate material 92 to the first plate material 91. The first plate material 91 functions as a heat-generating part, and the second plate material 92 functions as a heat-absorbing part. The Peltier element 9 acts as a heater for the protruding end 5a.

[0098] As a result, the protruding end 5a in contact with the first plate material 91 is heated by the Peltier element 9. The Peltier element 9 can function as a high-temperature part, and the battery assembly 3 can function as a low-temperature part. The heat released from the base end 5b is transferred to the battery assembly 3 via the heat transfer element 4. In some cases, such as immediately after starting up the battery module 1 in a cold region, the temperature of the battery cell 10 may be excessively low compared to the optimal temperature due to the influence of ambient temperature. In such cases, it becomes possible to actively and quickly raise the temperature of the battery cell 10 to the optimal temperature.

[0099] The applied state is controlled by a controller (not shown). The controller may be implemented by a CPU, memory, and input / output interface mounted on a circuit board, which is an example of a heat-generating component 8. The battery module 1 may have a temperature sensor for detecting the temperature of the battery cell 10. The controller may determine whether to set the applied state to a first applied state or a second applied state based on the value detected by the temperature sensor. In accordance with this determination, the joint 93 is energized, and heat is transferred between the first plate material 91 and the second plate material 92 in a direction corresponding to the applied state.

[0100] (Third Embodiment) Next, with reference to Figure 9, the battery module 1 according to the third embodiment will be described, focusing on the differences from the above embodiment.

[0101] In the first embodiment (see Figure 2), the airflow passes through the battery assembly 3, heat sink 6, fan 7, and heat-generating component 8 in that order. Alternatively, as shown in Figure 9, the airflow may pass through the battery assembly 3 after passing through the heat sink 6.

[0102] When the airflow flows from one side to the other in the longitudinal direction X, as in the first embodiment, the protrusion direction of the heat pipe 5 is reversed compared to the first embodiment. In this embodiment, the heat pipe 5 protrudes from the battery assembly 3 to one side in the longitudinal direction X (i.e., the upstream side of the airflow), so that the airflow passes over the heat sink 6 first. This further improves the heat dissipation performance of the heat sink 6.

[0103] (Fourth Embodiment) Next, with reference to Figure 10, the battery module 1 according to the fourth embodiment will be described, focusing on the differences from the above embodiment.

[0104] In the first embodiment (see Figure 2), the air drawn into the fan 7 passes through the battery assembly and the heat sink 6, and the air blown out from the fan 7 passes through the heat-generating component 8. Alternatively, as shown in Figure 10, the air blown out from the fan 7 may pass through the heat sink 6 and the battery assembly 3.

[0105] In this case, the fan 7 is positioned on one side of the longitudinal direction X (the upstream side of the airflow) relative to the battery assembly 3 and the heat sink 6. In this embodiment as well, the heat dissipation of the battery module 1 is improved, similar to the embodiments described above.

[0106] (Fifth Embodiment) Next, with reference to Figure 11, the battery module 1 according to the fifth embodiment will be described, focusing on the differences from the above embodiment.

[0107] In the fourth embodiment (see Figure 10), the airflow blown out from the fan 7 passes through the heat sink 6 and the battery assembly 3 in that order. Alternatively, as shown in Figure 11, the airflow blown out from the fan 7 may pass through the heat sink 6 after passing through the battery assembly 3. In this embodiment as well, the heat dissipation of the battery module 1 is improved, similar to the embodiments described above.

[0108] (Sixth Embodiment) Next, with reference to Figure 12, the battery module 1 according to the sixth embodiment will be described, focusing on the differences from the above embodiment.

[0109] In the first embodiment (see Figures 1 and 5), two flat heat pipes 5 are arranged in the width direction Y, and the two heat pipes 5 cover substantially the entire upper surface of the heat transfer element 4. Alternatively, as shown in Figure 12, one flat heat pipe 5 may cover substantially the entire upper surface of the heat transfer element 4. The width direction Y dimension of the heat pipe 5 is approximately twice that of the first embodiment.

[0110] (Seventh Embodiment) Next, with reference to Figure 13, the battery module 1 according to the seventh embodiment will be described, focusing on the differences from the above embodiment.

[0111] In the first embodiment (see Figures 1 and 5) and the sixth embodiment (see Figure 6), the upper surface of the heat transfer element 4 is covered by one or more flat heat pipes 5 over substantially the entire area. Alternatively, as shown in Figure 13, the heat pipe 5 may cover only the central part of the upper surface of the heat transfer element 4 in the width direction Y. In this case, a single plate-shaped heat pipe 5 may be used.

[0112] The airflow passes along the surface of the battery assembly 3. On the other hand, within the battery assembly 3, multiple battery cells 10 are arranged in a matrix or staggered pattern in the longitudinal direction X and the width direction Y. Battery cells 10 located in the center of both the longitudinal direction X and the width direction Y are less likely to be air-cooled than battery cells 10 located at both ends of the longitudinal direction X or both ends of the width direction Y.

[0113] According to this embodiment, since the heat pipe 5 is positioned in the central part, it is possible to relatively increase the amount of heat absorbed from the battery cells 10 in the central part. This promotes the removal of heat trapped in the central part and suppresses temperature variations between the battery cells 10.

[0114] (Eighth Embodiment) Next, with reference to Figure 14, the battery module 1 according to the eighth embodiment will be described, focusing on the differences from the above embodiment.

[0115] In the seventh embodiment (see Figure 13), the heat pipe 5 is flat. Alternatively, as shown in Figure 14, multiple cylindrical heat pipes 5 may be used. In this case, the heat pipes 5 may be densely arranged in the center of the width direction Y and sparsely arranged at both ends of the width direction Y. This makes it possible to suppress temperature variations between the battery cells 10 when there are differences in the air cooling effect between the battery cells 10, similar to the seventh embodiment.

[0116] (Ninth Embodiment) Next, with reference to Figure 15, the battery module 1 according to the ninth embodiment will be described, focusing on the differences from the above embodiment.

[0117] In the first embodiment (see Figures 1 and 5), the heat pipe 5 is separate from the heat transfer element 4 and is provided on the heat transfer element 4 so as to be superimposed on the upper surface of the heat transfer element 4. Alternatively, as shown in Figure 15, the container portion 51 of the heat pipe 5 may be integrally molded with the heat transfer element 4, particularly its plate 42. The molding method is not particularly limited, and extrusion molding can be applied as an example. This reduces the number of parts and assembly man-hours.

[0118] (Tenth Embodiment) Next, with reference to Figure 16, the battery module according to the tenth embodiment will be described, focusing on the differences from the above embodiment.

[0119] In the first embodiment (see Figures 1 and 4), the cell holder 20 includes a holder frame 21 and a plurality of blocks 23. Alternatively, the cell holder 20 may have a structure in which the portion corresponding to the block 23 in the first embodiment is integrated with the portion corresponding to the holder frame 21 in the first embodiment. In this case, the block grooves 27a, 28a and the corresponding frame grooves 27b, 28b (see Figure 4) are integrally continuous, so that the cell housing portion 25 is composed of through holes 26. To prevent the battery cells 10 from short-circuiting each other within the cell holder 20, the cell holder 20 is molded from the same insulating material as the holder frame 21.

[0120] The cell holder 20, like the holder frame 21 in the first embodiment, has a side wall 21b, a top surface 21g, and a female screw hole 21h. The top surface 21g may be flush with the surface as shown in the illustration. The top surface 21g may be recessed in the area corresponding to the block 23 (see Figure 4). The second end face portion 12 of the battery cell 10 is at the same height as or lower than the top surface 21g of the cell holder 20.

[0121] In this embodiment as well, heat can be removed from almost the entire upper surface 21g of the cell holder 20, improving the heat dissipation performance of the battery module.

[0122] Although embodiments have been described so far, the above configurations are merely illustrative and can be modified as appropriate within the scope of this disclosure.

[0123] The shape of the outer casing 2 can be appropriately changed depending on the application of the battery module 1, or depending on the shape or size of the space available for the battery module 1 at the application site. The arrangement of the components housed in the outer casing 2 can also be appropriately changed. For example, the outer casing 2 may be made larger in the height direction Z than those shown in Figures 1 and 2. In that case, the height constraints on the components housed in the outer casing 2 are relaxed. The heat sink 6 may be positioned on the opposite side of the battery assembly 3 in the height direction Z from the heat pipe 5. The heat pipe 5 does not necessarily have to extend in a straight line and may have curved sections.

[0124] This disclosure may include the following embodiments: (Embodiment 1) A battery module comprising: a plurality of battery cells; a cell holder for holding the plurality of battery cells; a heat transfer element laminated on the cell holder and performing heat exchange with the plurality of battery cells or the cell holder; a heat pipe provided on the heat transfer element, having a protruding end protruding from the cell holder; a heat sink provided on the protruding end; and a fan for cooling the heat sink. (Embodiment 2) The battery module according to Embodiment 1, wherein the heat transfer element comprises a thermal interface material laminated on the cell holder and a plate laminated on the thermal interface material. (Aspect 3) The battery module according to aspect 2, wherein the plurality of battery cells constitute a plurality of parallel units, each of the parallel units consists of two or more of the battery cells connected in parallel to each other, the plurality of parallel units are connected in series sequentially, the cell holder includes a holder frame made of an insulating material and provided with a plurality of block housing sections, and a plurality of blocks each housed in the plurality of block housing sections, the blocks are made of a material having higher thermal conductivity than the insulating material and each has two or more cell housing sections for housing the two or more of the battery cells constituting a set of the parallel units, and the thermal interface material is insulating and covers the plurality of blocks. (Aspect 4) The battery module according to any one of aspects 1 to 3, wherein the heat pipe has a container section for sealing a working fluid, and the container section is plate-shaped. (Aspect 5) The battery module according to any one of aspects 1 to 4, further comprising a Peltier element interposed between the protruding end and the heat sink. (Aspect 6) The battery module according to aspect 5, wherein the Peltier element includes a first plate material that contacts the heat pipe and a second plate material that contacts the heat sink, and the applied state of the Peltier element switches between a first applied state in which the first plate material becomes a heat-absorbing part and the second plate material becomes a heat-generating part, and a second applied state in which the first plate material becomes a heat-generating part and the second plate material becomes a heat-absorbing part.

[0125] 1. Battery module 2. Outer case 2a. Internal space 2b. Bottom wall 2c. Top wall 2d. Side wall 2e. First end wall 2f. Second end wall 2g, 2h. Ventilation holes 2A. Base 2B. Cover 3. Battery assembly 4. Heat transfer element 5. Heat pipe 5a. Protruding end 5b. Base end 6. Heat sink 7. Fan 8. Heat generating component 9. Peltier element 10. Battery cell 11. First end face 12. Second end face 13. Side surface 14. Peripheral electrode 15. Central electrode 16. Outer can 17. Sealing plate 18. Cell row 19. Parallel unit 20. Cell holder 21. Holder frame 21a. Bottom wall 21b. Side wall 21c, 21d. End wall 21e. Partition wall 21f. Opening 21g. Top surface 21h Female screw hole 22 Block housing section 22a, 22b Opposing wall 23 Block 23a Bottom surface 23b Top surface 23c, 23d Side surface 25 Cell housing section 26 Through hole 27a, 28a Block groove 27b, 28b Frame groove 30 Current collection structure 31 First current collector group 31A First current collector plate 32 Insulating layer 33 Second current collector group 33A Second current collector plate 41 Thermal interface material 42 Plate 42a Pipe fixing groove 42b Ridge 42c Through hole 51 Container section 52 Working fluid 61 Base plate 61a Upper wall section 61b Lower wall section 62 Fin 63 Slot 64 Female screw 71 Bolt 72 Male screw 91 First plate material 92 Second plate material 93 Joint X Longitudinal direction Y Width direction Z Height direction

Claims

1. A battery module comprising: a plurality of battery cells; a cell holder for holding the plurality of battery cells; a heat transfer element stacked on the cell holder and performing heat exchange with the plurality of battery cells or the cell holder; a heat pipe provided on the heat transfer element, having a protruding end that extends outward from the cell holder; a heat sink provided on the protruding end; and a fan for cooling the heat sink.

2. The battery module according to claim 1, wherein the heat transfer element comprises a thermal interface material laminated on the cell holder and a plate laminated on the thermal interface material.

3. The battery module according to claim 2, wherein the plurality of battery cells constitute a plurality of parallel units, each of the parallel units consists of two or more of the battery cells connected in parallel to one another, the plurality of parallel units are connected sequentially in series, the cell holder includes a holder frame made of an insulating material and provided with a plurality of block housing sections, and a plurality of blocks each housed in the plurality of block housing sections, the blocks are made of a material having higher thermal conductivity than the insulating material and each has two or more cell housing sections for housing the two or more of the battery cells constituting a set of the parallel units, and the thermal interface material is insulating and covers the plurality of blocks.

4. The battery module according to any one of claims 1 to 3, wherein the heat pipe has a container portion for sealing a working fluid, and the container portion is plate-shaped.

5. The battery module according to any one of claims 1 to 3, further comprising a Peltier element interposed between the protruding end and the heat sink.

6. The battery module according to claim 5, wherein the Peltier element includes a first plate material that contacts the heat pipe and a second plate material that contacts the heat sink, and the applied state of the Peltier element switches between a first applied state in which the first plate material becomes a heat-absorbing part and the second plate material becomes a heat-generating part, and a second applied state in which the first plate material becomes a heat-generating part and the second plate material becomes a heat-absorbing part.

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