Battery module

Abstract

To provide a battery module that comprises a separator capable of reducing reaction generated in a bus bar provided between battery cells, in either of the case where an impact is applied to the battery module from the outside and the case where the battery cell is expanded.SOLUTION: A battery module comprises a plurality of battery cells that are arrayed in a first direction (Y-direction), and a separator 400 that is sandwiched between the plurality of battery cells. The separator 400 includes a body part 410 having an internal space 420, and a liquid 430 that is stored to fill a part of the internal space 420.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] As a prior art document disclosing a configuration in which a separator is disposed between battery cells of a battery module, there is Japanese Unexamined Patent Application Publication No. 2018-098082 (Patent Document 1). In the separator described in Patent Document 1, when pressurized air is introduced therein and the separator expands, the battery cell disposed between two adjacent separators is in a state where the thickness direction is pressurized.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the separator described in Patent Document 1, when a battery cell is inserted into a housing using a robot hand, the pressurized air is discharged and the separator contracts, so that the space between adjacent spacers expands, facilitating the insertion of the battery cell. On the other hand, by introducing pressurized air into the separator, the battery cell is pressurized and fixed by the separator in the housing.

[0005] However, when the battery module is used, it is conceivable that an impact is applied to the battery module from the outside or the battery cell expands. In such a case, in the separator described in Patent Document 1, in any case, it is difficult to reduce the reaction force generated in the bus bar provided between the battery cells.

[0006] The present technology has been made to solve the above problems, and in any case where an impact is applied to the battery module from the outside or when the battery cell expands, a separator is provided between the battery cells to reduce the reaction force generated in the bus bar. The purpose is to provide a battery module.

Means for Solving the Problems

[0007] The present technology provides the following battery module.

[0008] [1]: A battery module including a plurality of battery cells arranged in a first direction and a separator sandwiched between the plurality of battery cells, the separator including a main body portion having an internal space and a fluid accommodated so as to fill a part of the internal space.

[0009] [2]: The battery module according to [1], wherein a member for narrowing the internal space is provided on an inner wall of the main body portion.

[0010] [3]: The battery module according to [2], wherein the member is a foam placed in the internal space.

[0011] [4]: The battery module according to any one of [1] to [3], wherein the fluid has a predetermined viscosity.

[0012] [5]: The battery module according to any one of [1] to [4], wherein the fluid is a liquid.

[0013] [6]: The battery module according to [5], wherein the main body portion is deformable in a direction to reduce the volume of the internal space by pressurization from the first direction, and the liquid flows when the volume of the internal space decreases.

Advantages of the Invention

[0014] According to the present technology, a separator is provided that enables reduction of the reaction force generated in a bus bar provided between battery cells, in any case where an impact is applied to the battery module from the outside or where the battery cell expands, thereby enabling the provision of a battery module.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts may be denoted by the same reference numerals, and the description thereof may not be repeated.

[0017] In the embodiments described below, when referring to the number, amount, etc., unless otherwise specified, the scope of the present technology is not necessarily limited to such number, amount, etc. In the following embodiments, each component is not necessarily essential for the present technology, unless otherwise specified. The present technology is not necessarily limited to those that exhibit all of the effects described in the present embodiments.

[0018] In this specification, the descriptions of "comprise", "include", and "have" are in an open - ended form. That is, when a certain configuration is included, other configurations outside the said configuration may or may not be included.

[0019] In this specification, when geometric terms and terms representing positional and directional relationships, such as "parallel", "orthogonal", "diagonal 45°", "coaxial", "along", etc. are used, those terms allow for manufacturing errors or slight variations. In this specification, when terms representing relative positional relationships such as "upper side", "lower side", etc. are used, those terms are used to indicate the relative positional relationship in one state, and depending on the installation direction of each mechanism (for example, turning the entire mechanism upside down, etc.), the relative positional relationship can be reversed or rotated at an arbitrary angle.

[0020] In this specification, the "battery" is not limited to a lithium-ion battery, and may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the "electrode" may generically refer to a positive electrode and a negative electrode.

[0021] The "battery module" can be mounted on a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a battery electric vehicle (BEV), etc. However, the use of the "battery module" is not limited to in-vehicle use.

[0022] In the drawings, when looking at the virtual plane orthogonal to the first direction (Y direction) in which a plurality of battery cells are arranged, the direction in which the positive and negative terminals of the battery cells are arranged and which is included in the virtual plane is defined as the second direction (X direction), and the direction in which the upper and lower surfaces of the battery cells are arranged and which is included in the virtual plane and orthogonal to the second direction is defined as the third direction (Z direction). For the sake of facilitating the understanding of this technology, there are parts where the dimensions of each component in the drawings are shown as changed from the actual dimensions.

[0023] (Embodiment 1) The configuration of the battery module according to Embodiment 1 will be described. FIG. 1 is a perspective view showing the configuration of the battery module 1, and FIG. 2 is a perspective view showing the internal configuration of the battery module 1.

[0024] Referring to FIGS. 1 and 2, the battery module 1 includes battery cells 100, end plates 200, restraint members 300, and separators 400.

[0025] A plurality of battery cells 100 are arranged in the first direction (Y direction). A separator 400, which will be described later, is disposed between the battery cells 100. The plurality of battery cells 100 sandwiched between two end plates 200 are pressed by the end plates 200 via the separators 400 and are restrained between the two end plates 200.

[0026] The end plate 200 is provided at both ends of the plurality of battery cells 100 in the first direction (Y direction). The end plate 200 is fixed to a base such as a housing that houses the battery module 1. The end plate 200 is made of, for example, aluminum or iron.

[0027] Referring to FIG. 1, the restraining member 300 is provided at both ends of the plurality of battery cells 100 and the end plate 200 in the X direction. The restraining member 300 is engaged with the end plate 200 in a state where a compressive force in the Y direction is applied to the stacked plurality of battery cells 100 and the end plate 200, and then the compressive force is released, so that a tensile force acts on the restraining member 300 that connects the two end plates 200. As a reaction, the restraining member 300 presses the two end plates 200 in a direction approaching each other. As a result, the restraining member 300 restrains the plurality of battery cells 100 in the Y direction.

[0028] The separator 400 is disposed between the plurality of battery cells 100. The separator 400 is disposed between the battery cell 100 located at the end in the Y direction among the plurality of battery cells 100 and the end plate 200. The separator 400 abuts on the long side surface of the plurality of battery cells 100 or the long side surface of the end plate 200.

[0029] The separator 400 has insulation. Thereby, the separator 400 insulates the plurality of battery cells 100 from each other or the battery cell 100 and the end plate 200. Details of the separator 400 will be described later.

[0030] FIG. 3 is a perspective view showing the configuration of the battery cell 100 included in the battery module 1. Referring to FIG. 3, the battery cell 100 includes an electrode terminal 110, a case 120, a gas discharge valve 130, and an electrode body 140.

[0031] The electrode terminal 110 is formed on the case 120. The electrode terminal 110 has a positive electrode terminal 111 and a negative electrode terminal 112. The positive electrode terminal 111 and the negative electrode terminal 112 are arranged side by side in the second direction (X direction).

[0032] The case 120 is a container that houses the electrode body 140 and the electrolytic solution. The case 120 has a substantially rectangular parallelepiped shape. The case 120 is made of, for example, aluminum, an aluminum alloy, iron, or an iron alloy.

[0033] The case 120 has an upper surface 121, a lower surface 122, a pair of long side surfaces 123, and a pair of short side surfaces 124. The electrode terminal 110 is arranged on the upper surface 121. The lower surface 122 faces the upper surface 121 in the third direction (Z direction).

[0034] The pair of long side surfaces 123 and the pair of short side surfaces 124 constitute the side surfaces of the case 120. The pair of long side surfaces 123 and the pair of short side surfaces 124 as the side surfaces of the case 120 intersect each of the upper surface 121 and the lower surface 122. Each of the pair of long side surfaces 123 faces each other with the electrode body 140 sandwiched therebetween in the first direction (Y direction). Each of the pair of short side surfaces 124 faces each other with the electrode body 140 sandwiched therebetween in the second direction (X direction). Each of the pair of long side surfaces 123 has a larger area than each of the pair of short side surfaces 124.

[0035] The gas discharge valve 130 breaks when the pressure inside the case 120 becomes equal to or higher than a predetermined value. Thereby, the gas inside the case 120 is discharged to the outside of the case 120.

[0036] The electrode body 140 functions as a power generation element. The electrode body 140 includes a positive electrode and a negative electrode (not shown). The base material constituting the positive electrode is, for example, an aluminum alloy foil. The base material constituting the negative electrode is, for example, a copper alloy foil. The electrode body 140 is, for example, a wound electrode body in which the positive electrode and the negative electrode are wound, or a laminated electrode body in which the positive electrode and the negative electrode are alternately laminated.

[0037] (Separator 400) Next, with reference to FIGS. 4 to 6, the configuration of the separator 400 will be described. FIG. 4 is a perspective view showing the configuration of the separator 400, FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4, and FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 4.

[0038] The separator 400 includes a main body portion 410 having an internal space 420, and a liquid 430 accommodated so as to fill a part of the internal space 420.

[0039] The main body portion 410 has an upper surface 411, a lower surface 412, a pair of long side surfaces 413, and a pair of short side surfaces 414. The lower surface 412 faces the upper surface 411 in the third direction (Z direction).

[0040] The pair of long side surfaces 413 and the pair of short side surfaces 414 constitute the side surfaces of the separator 400. The pair of long side surfaces 413 and the pair of short side surfaces 414 as the side surfaces of the separator 400 intersect each of the upper surface 411 and the lower surface 412. Each of the pair of long side surfaces 413 faces each other in the first direction (Y direction). Each of the pair of short side surfaces 414 faces each other in the second direction (X direction). Each of the pair of long side surfaces 413 has a larger area than each of the pair of short side surfaces 414.

[0041] The size and thickness of the separator 400 may be such that it does not protrude from the battery cell 100 when the separator 400 is compressed by the battery cell 100. When the separator 400 is compressed, the outer periphery of the separator 400 bulges, so a size smaller than the size of the battery cell 100 is preferable. The thickness of the separator 400 in the first direction (Y direction) is preferably about 0.5 mm to 10 mm.

[0042] The main body 410 of the separator 400 is mainly required to function as a fluid reservoir. Suitable materials include PPS (polyphenylene sulfide), polyvinyl chloride, polyethylene, PC (polycarbonate), and PP (polypropylene). The thickness of the main body 410 (see Figure 6, D) is about 0.1 mm to 3 mm. The width of the internal space 420 (see Figure 6, W) is about 1 mm to 9 mm.

[0043] In this embodiment, the fluid accommodated in the internal space 420 of the main body 410 is the liquid 430, and water, silicone oil, ethylene glycol, mineral oil, etc. can be used. The viscosity of the liquid may be 1 mPa·s to 1000 mPa·s, preferably 1 mPa·s to 100 mPa·s, and more preferably 1 mPa·s to 50 mPa·s. Note that it is not limited to the liquid 430, and fluids having equivalent functions can be used.

[0044] [[ID=S7]] Next, referring to FIGS. 7 to 11, the state during charging and the state during vibration when the separator is sandwiched by the battery cells will be described. FIG. 7 is a schematic diagram of the state during charging when the separator is sandwiched by the battery cells, FIG. 8 is a diagram showing the relationship between the acceleration and the pressure loss generated in the fluid, FIG. 9 is a diagram showing the relationship between the acceleration (V) and the fluid movement during charging and discharging and during vibration and shock of the battery cell, FIG. 10 is a schematic diagram of the state where the battery module is subjected to vibration and shock, and FIG. 11 is a schematic diagram showing the relationship between the internal space provided in the separator and the fluid.

[0045] Referring to FIG. 7, when the battery cell 100 is charged, the battery cell 100 expands. At this time, the pair of long side surfaces 413 of the separator 400 are provided to be deformable in a direction to reduce the volume of the internal space 420 by pressurization from the first direction (Y direction), and the liquid 430 flows as the volume of the internal space 420 decreases. In this way, the internal space 420 shrinks, and the liquid 430 in the internal space 420 moves upward (the direction indicated by the arrow Z1 in the figure).

[0046] As a result, when the battery cell 100 expands, the separator 400 deforms, so that the change in the distance between the battery cells 100 located on both sides can be reduced.

[0047] As a result, since the distance between the battery cells 100 located on both sides of the separator 400 is small, the external force applied to the bus bar BB connecting the battery cells 100 located on both sides of the separator 400 can be reduced.

[0048] Referring to FIG. 8, the pressure loss generated in the liquid 430 accommodated in the internal space 420 of the separator 400 will be described. The pressure loss (h) generated in the liquid 430 is represented by Equation 1 in FIG. 8. Based on Equation 1, the pressure loss of the liquid 430 is proportional to the square of the sedimentation velocity (V). Therefore, the higher the sedimentation velocity, the more difficult it is for the liquid 430 to move (the more solid it becomes).

[0049] Furthermore, referring to FIG. 9, the force applied to the separator 400 during charging of the battery cell 100, that is, the sedimentation velocity (V) when the battery cell 100 expands, is small. For example, during normal use charging or rapid charging, it is about 0.5 mm / 0.5 h to 0.5 mm / 5 h. As a result, the pressure loss generated in the liquid 430 is small, and the liquid 430 is in a state where it is easy to move in the internal space 420. Therefore, the expansion during charging and discharging of the battery cell 100 can be tolerated by the deformation of the separator 400.

[0050] As a result, since the change in the distance between the battery cells 100 located on both sides of the separator 400 is reduced, the external force applied to the bus bar BB connecting the battery cells 100 located on both sides of the separator 400 can be reduced.

[0051] Next, referring to FIG. 10, when an oscillatory impact force F1 is applied to the battery module 1, a large impact force is applied to the battery cell 100 and the separator 400. In this case, the acceleration rate (V) is as large as 1 mm / 2 msec to 1 mm / 100 msec as shown in FIG. 9 again. As a result, the pressure loss generated in the liquid 430 is large, and the liquid 430 is in a state where it is difficult to move in the internal space 420. Therefore, when the oscillatory impact force F1 is applied, since the liquid 430 does not move significantly, the deformation of the separator 400 is small.

[0052] As described above, when an impact force is applied from the outside, since the deformation of the separator 400 is small, the external force applied to the bus bar BB that connects between the battery cells 100 located on both sides of the separator 400 can be reduced.

[0053] Next, referring to FIG. 11, the liquid 430 accommodated in the internal space 420 of the separator 400 preferably has its liquid level rise and fill the deformed internal space 420 when the separator 400 is compressed by about 2 / 3 in the thickness direction.

[0054] During charging and discharging of the battery cell 100, the separator 400 is compressed by 10% to 50% in the width direction (Y direction). Therefore, the height position of the liquid level of the liquid 430 is preferably 50% (1 / 2) or more and 90% or less, preferably 50% to 75%, and more preferably 50% to 66% with respect to the capacity in the internal space 420 in a state where the separator 400 is not deformed. Also, when the height in the internal space 420 is H1, the liquid level height of the liquid 430 is preferably (2 / 3)×H1.

[0055] Furthermore, the height position of the liquid level of the liquid 430 is preferably provided higher than the center of gravity position of the battery cell 100 (for example, the position at 1 / 2 of the Z-direction height of the battery cell).

[0056] As described above, in the battery module 1 of the present embodiment, when an impact is applied to the battery module 1 from the outside or when the battery cell 100 expands, in any case, it is possible to reduce the reaction force generated in the bus bar provided between the battery cells 100.

[0057] (Embodiment 2) Next, with reference to FIGS. 12 to 15, the form of the separator in Embodiment 2 will be described. FIG. 12 is a cross-sectional view showing the configuration of the separator 400A and corresponds to a cross-section taken along the line V-V in FIG. 4. FIG. 13 is a cross-sectional view taken along the line XIII-XIII in FIG. 12, and FIGS. 14 and 15 are the first and second diagrams showing the pressure loss generated in the fluid.

[0058] In the separator 400A of the present embodiment, an internal wall 440 that vertically partitions the internal space 420 is provided on the inner wall of the main body portion 410 of the internal space 420. Further, the internal wall 440 is provided with a communication passage 450 that communicates the upper space and the lower space when the internal wall 440 partitions the upper space and the lower space. In the present embodiment, the position where the internal wall 440 is provided is such that the lower surface of the internal wall 440 is provided at a position substantially the same as the liquid level of the liquid 430.

[0059] The communication passage 450 provided in the internal wall 440 constitutes a region that narrows the internal space 420. Here, with reference to FIGS. 14 and 15, the operation and effect of providing a region that narrows the internal space 420 will be described.

[0060] As shown in FIGS. 15 and 16, by providing a region that narrows the internal space 420, the pressure loss generated in the liquid 430 can be regarded as the pressure loss that occurs when the flow path area shrinks from A1 to A2 as shown in FIG. 14, or the pressure loss that occurs when the angle of the flow path is changed as shown in FIG. 19. In either case of FIGS. 18 and 19, the pressure loss generated in the fluid is proportional to the square of the velocity of the liquid 430. Therefore, in either state when the battery cell 100 shown in FIG. 7 is being charged and when the vibration impact force F1 is applied to the battery module 1 shown in FIG. 10, it is possible to effectively prevent an external force from being applied to the bus bar.

[0061] (Embodiment 3) Next, with reference to FIGS. 16 and 17, a modified example of the internal wall provided in the separator in Embodiment 3 will be described. FIGS. 16 and 17 are diagrams showing first and second modified examples of the internal wall provided in the separator.

[0062] In the separator 400B shown in FIG. 16, the internal wall 440 is provided at a position below the normal liquid level of the liquid 430. Even in this configuration, the same operational effects as those of the separator 400A shown in Embodiment 2 above can be obtained.

[0063] In the separator 400C shown in FIG. 17, the opposing internal walls 440 are provided so as to protrude toward the internal space 420, and a communication passage 450 serving as a region that narrows the internal space 420 is defined between the protruding internal walls 440. Even in this configuration, the same operational effects as those of the separator 400A shown in Embodiment 2 above can be obtained.

[0064] Note that, as another form of the separator, as a member that narrows the internal space 420 of the main body portion 410, a configuration in which a foam in which liquid is occluded in communicating holes is placed in the internal space 420 may be adopted.

[0065] In each embodiment, the separator disposed between a plurality of battery cells has been described. However, the same configuration as the above-described separator can also be applied to the separator disposed between the battery cell and the end plate. Further, in this specification, having the same dimensions means that the dimensions are the design values without including manufacturing tolerances.

[0066] As described above, the embodiments of the present technology have been described. However, it should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present technology is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

Explanation of Reference Numerals

[0067] 1 Battery module, 100 Battery cell, 110 Electrode terminal, 111 Positive electrode terminal, 112 Negative electrode terminal, 120 Case, 121, 411 Upper surface, 122, 412 Lower surface, 123, 413 Long side surface, 124, 414 Short side surface,

Claims

1. A plurality of battery cells arranged in a first direction, A separator sandwiched between the plurality of battery cells, Comprising, The separator is, A main body portion having an internal space, A fluid accommodated so as to fill a part of the internal space, and includes, A battery module.

2. On the inner wall of the main body portion, a member for narrowing the internal space is provided, The battery module according to claim 1.

3. The member is a foam placed in the internal space, The battery module according to claim 2.

4. The fluid has a predetermined viscosity, The battery module according to claim 1.

5. The fluid is a liquid, The battery module according to claim 1.

6. The main body portion is, Deformable in a direction of reducing the volume of the internal space by pressurization from the first direction, and the liquid flows by the reduction of the volume of the internal space, The battery module according to claim 5.

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