Battery module

Abstract

To provide a battery module that more evenly distributes the deposition of lithium metal in a planar direction perpendicular to the stacking direction of battery cells during charging and discharging. [Solution] The battery module 1 comprises a battery cell 20 which is a laminate having a positive electrode layer 21, a negative electrode layer 22, and a solid electrolyte layer 23 located between the positive electrode layer 21 and the negative electrode layer 22, and includes pressurizing mechanisms 30, 30A, 30B, and 30C that apply pressure to the battery cell 20 from both sides in the stacking direction of the laminate and apply different pressures depending on the position in the planar direction perpendicular to the stacking direction of the laminate, and a control unit 50 that controls the pressurizing mechanisms 30, 30A, 30B, and 30C based on temperature information regarding the temperature of the battery cell 20 at multiple locations where the battery cell 20 is located at different positions in the planar direction, so that a pressure corresponding to the temperature information of each of the multiple locations is applied to each of the multiple locations.

Description

[Technical Field]

[0001] This invention relates to a battery module. [Background technology]

[0002] In light of climate-related disasters, interest in electric vehicles is growing as a way to reduce CO2 emissions, and the installation of battery modules with stacked battery cells in electric vehicles is being considered.

[0003] A battery module includes, for example, a battery cell which is a laminate having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between them. Because the battery cell expands and contracts with charging and discharging, pressure is applied to the battery cell from both sides in the stacking direction. For example, Patent Document 1 describes a solid-state battery comprising a plurality of stacked battery cells, a pressurizing mechanism disposed on top of the plurality of stacked battery cells that applies restraining pressure to these battery cells, and a control device capable of adjusting the restraining pressure on the solid-state battery according to the internal resistance value of the solid-state battery. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-39190 [Overview of the project] [Problems that the invention aims to solve]

[0005] By the way, when cooling or heating battery cells that expand and contract, the cooling / heating is mainly done on one side of the battery module (mainly the bottom side). However, because only one side is cooled / heated, temperature variations such as temperature gradients inevitably occur within the battery cell. When temperature variations occur within the cell, the resistance difference within the cell also increases, causing variations in thickness within the cell surface, which may lead to variations in the deposition of lithium metal within the cell.

[0006] The present invention aims to provide a battery module that more evenly distributes the deposition of lithium metal in a planar direction perpendicular to the stacking direction of battery cells during charging and discharging. [Means for solving the problem]

[0007] (1) The battery module comprises a battery cell which is a laminate having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer, and includes a pressurizing mechanism which applies pressure to the battery cell from both sides in the stacking direction of the laminate and can apply different pressures depending on the position in a planar direction perpendicular to the stacking direction of the laminate, and a pressure control unit which controls the pressurizing mechanism based on temperature information relating to the temperature of the battery cell at a plurality of locations where the battery cell is located at different positions in the planar direction, so that a pressure corresponding to the temperature information of each of the plurality of locations is applied to each of the plurality of locations.

[0008] (2) In the battery module described in (1), a plurality of battery cells are stacked in the stacking direction to form a battery cell stack, and the pressurizing mechanism comprises a pair of plate-shaped members provided at both ends of the battery cell stack in the stacking direction, and the pressure control unit controls the pressurizing mechanism so that a force is applied to the pair of plate-shaped members in a direction that changes the inclination of the pair of plate-shaped members with respect to the plane direction, thereby causing the pressurizing mechanism to apply different pressures depending on the position in the plane direction.

[0009] (3) In the battery module described in (1) or (2), the pressure control unit controls the pressurizing mechanism such that it reduces the pressure applied to a part where the temperature indicated by the temperature information is higher than a predetermined threshold, and increases the pressure applied to a part where the temperature indicated by the temperature information is lower than a predetermined threshold.

[0010] (4) In the battery module described in (1) or (2), the temperature information is the temperature variation of the battery cell in the planar direction, and the pressure control unit adjusts the pressure applied to each of the plurality of parts based on the resistance difference within the battery cell caused by the temperature variation of the battery cell in the planar direction.

[0011] (5) In the battery module described in (1) or (2), the battery cells are stacked in the stacking direction to form the battery cell stack, and the pressure control unit controls the pressurizing mechanism such that the higher the temperature of the battery cell stack, the greater the pressure difference applied to each of the multiple parts in the planar direction of the battery cell stack, and the lower the temperature of the battery cell stack, the smaller the pressure difference. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a battery module that more evenly distributes the deposition of lithium metal in a planar direction perpendicular to the stacking direction of battery cells due to charging and discharging. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing a battery module relating to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing a stack of battery cells as viewed from the stacking direction. [Figure 3] This is a functional block diagram illustrating the relationship between the control unit, sensor group, and pressurization mechanism of a battery module according to one embodiment of the present invention. [Figure 4] This is a schematic diagram illustrating a pressurization mechanism in which the pressure applied to the lower side of the battery cell stack is relatively high. [Figure 5A] This is a schematic diagram showing the temperature distribution and resistance of a battery cell stack when a cooling water jacket is placed on the bottom surface of the battery module. [Figure 5B]It is a diagram showing the resistance when the lower side of a battery cell laminate is pressed against the battery module shown in Fig. 5A. [Figure 6A] It is a schematic diagram showing the temperature distribution and resistance of a battery cell laminate when a heating water jacket is arranged on the bottom surface of a battery module. [Figure 6B] It is a diagram showing the resistance when the upper side of a battery cell laminate is pressed against the battery module shown in Fig. 6A. [Figure 7] It is a graph showing the relationship between the temperature and resistance of a battery cell. [Figure 8A] It is a diagram showing a first modification example of a pressing mechanism, and is a schematic diagram showing a state where the pressure applied to the lower side of a battery cell laminate becomes relatively high. [Figure 8B] It is a diagram showing a first modification example of a pressing mechanism, and is a schematic diagram showing a state where equal pressures are applied to the upper and lower sides of a battery cell laminate. [Figure 8C] It is a diagram showing a first modification example of a pressing mechanism, and is a schematic diagram showing a state where the pressure applied to the upper side of a battery cell laminate becomes relatively high. [Figure 9A] It is a diagram showing a second modification example of a pressing mechanism, and is a schematic diagram showing a state where the pressure applied to the lower side of a battery cell laminate becomes relatively high. [Figure 9B] It is a diagram showing a second modification example of a pressing mechanism, and is a schematic diagram showing a state where equal pressures are applied to the upper and lower sides of a battery cell laminate. [Figure 9C] It is a diagram showing a second modification example of a pressing mechanism, and is a schematic diagram showing a state where the pressure applied to the upper side of a battery cell laminate becomes relatively high. [Figure 9D] It is a diagram showing a second modification example of a pressing mechanism, and is a schematic diagram showing a state where the pressure applied to the upper side of a battery cell laminate becomes relatively high. [Figure 10A] It is a diagram showing a third modification example of a pressing mechanism, and is a schematic diagram showing a state where the pressure applied to the upper side of a battery cell laminate becomes relatively high. [Figure 10B]This diagram shows a third modified example of the pressurization mechanism, and is a schematic diagram illustrating a state in which equal pressure is applied to the upper and lower sides of the battery cell stack. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments shown below are illustrative of the present invention and are not limited to these embodiments.

[0015] Figure 1 is a schematic diagram showing a battery module according to this embodiment. Figure 2 is a schematic diagram showing a battery cell stack when viewed from the stacking direction. Figure 3 is a functional block diagram of the control unit 50 and other components of the battery module 1.

[0016] In Figure 1, arrow Y indicates the stacking direction of the battery cells 20 of the battery module 1. In Figures 1 and 2, arrow Z indicates the height direction of the battery module 1, with Z1 indicating the top and Z2 indicating the bottom. In Figure 2, arrow X indicates the width direction of the battery module 1. Note that the plane direction perpendicular to the stacking direction of the stacked body, the plane direction perpendicular to the stacking direction of the battery cells 20, and the plane direction perpendicular to the stacking direction of the battery cell stacked body 10 all refer to the XZ plane direction, and in this specification, these are also referred to as the XZ plane direction.

[0017] The battery module 1 comprises a battery cell stack 10 in which multiple battery cells 20 are stacked, a pressurizing mechanism 30, a sensor group 40, a control unit 50, and a water jacket 60.

[0018] (Battery cell) The battery cell 20 is a laminate having a positive electrode layer 21, a negative electrode layer 22, and a solid electrolyte layer 23. The battery cell 20 is preferably a solid battery cell such as an all-solid-state lithium-ion battery cell or an all-solid-state lithium metal battery cell. This is because the above-mentioned battery cell 20 exhibits a greater degree of expansion and contraction during charging and discharging compared to other types of battery cells, thus allowing the effects of the present invention to be preferably exhibited.

[0019] The positive electrode layer 21 contains at least one kind of positive electrode active material. As the positive electrode active material, for example, a layered active material containing lithium, a spinel-type active material, an olivine-type active material, etc. can be used. Specific examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), LiNi p Mn q Co r O2 (p + q + r = 1), LiNi p Al q Co r O2 (p + q + r = 1), lithium manganate (LiMn2O4), Li 1+x Mn 2-x-y MO4 (x + y = 2, M = at least one selected from Al, Mg, Co, Fe, Ni, and Zn), a hetero-element-substituted Li-Mn spinel represented by this, lithium titanate (an oxide containing Li and Ti), lithium metal phosphate (LiMPO4, M = at least one selected from Fe, Mn, Co, and Ni) can be mentioned.

[0020] The negative electrode layer 22 contains at least one kind of negative electrode active material. As the negative electrode active material, for example, lithium metal (including lithium metal alone, a lithium alloy, and mixtures thereof), a silicon-based active material such as Si, Si alloy, etc., lithium transition metal oxide such as lithium titanate (Li4Ti5O 12 ) etc., transition metal oxides such as TiO2, Nb2O3, and WO3, metal sulfides, metal nitrides, carbon materials such as graphite, soft carbon, and hard carbon, metal indium, etc. can be mentioned.

[0021] The positive electrode layer 21 and the negative electrode layer 22 may contain materials that can be contained in the active material layer of the solid battery other than the above. Examples of the above materials include, for example, a solid electrolyte, a conductive aid, a binder, etc.

[0022] The solid electrolyte layer 23 contains at least one type of solid electrolyte. The solid electrolyte is not particularly limited, but examples include inorganic solid electrolytes such as sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, and lithium-containing salts, as well as polymer-based solid electrolytes such as polyethylene oxide.

[0023] (Battery cell stack) The battery cell stack 10 is formed by stacking multiple battery cells 20 along the Y direction. A water jacket 60 is placed on the bottom surface 11 side of the battery cell stack 10.

[0024] (Water jacket) The water jacket 60 is a flow path for a heat transfer medium, such as cooling water or heated water. The water jacket 60 is arranged to exchange heat with the battery cell stack 10.

[0025] (Pressurization mechanism) The pressurizing mechanism 30 applies pressure to the battery cells 20 from both sides in the stacking direction of the battery cell stack 10, and can apply different pressures depending on the position in the plane direction perpendicular to the stacking direction of the battery cell stack 10. The pressurizing mechanism 30 consists of a pair of end plates 31 and 32, an upper expansion / contraction member 33, a lower expansion / contraction member 34, an upper air supply device 35, and a lower air supply device 36.

[0026] A pair of end plates 31 and 32 are provided at both ends of the battery cell stack 10 in the stacking direction. The pair of end plates 31 and 32 are housed in a battery case (not shown). In this embodiment, as shown in Figure 1, the end plate 31 is positioned at one end (left side in Figure 1) in the stacking direction of the battery cell stack 10, and the end plate 32 is positioned at the other end (right side in Figure 1) in the stacking direction of the battery cell stack 10.

[0027] As shown in Figure 1, the end plate 31 has an inner plate-shaped member (plate-shaped member) 311 and an outer plate-shaped member 312, and the end plate 32 has an inner plate-shaped member (plate-shaped member) 321 and an outer plate-shaped member 322.

[0028] The inner plate-like members 311 and 321 each make surface contact with the entire surface of the battery cell stack 10 perpendicular to the stacking direction. The inner plate-like member 311 makes surface contact with one end face in the stacking direction of the battery cell stack 10. The inner plate-like member 321 makes surface contact with the other end face in the stacking direction of the battery cell stack 10. When the battery cell stack 10 is not placed on the end plates 31 and 32, the inner plate-like members 311 and 321 are configured to be movable in the stacking direction.

[0029] The outer plate-shaped member 312 is positioned so as to face one end face of the battery cell stack 10, with the inner plate-shaped member 311 in between. The outer plate-shaped member 312 is fixed in a state where its outer surface is in contact with the inner surface of the battery case. An upper expansion / contraction member 33 and a lower expansion / contraction member 34 are positioned between the outer plate-shaped member 312 and the inner plate-shaped member 311.

[0030] The outer plate-shaped member 322 is positioned so as to face the other end face of the battery cell stack 10, with the inner plate-shaped member 321 in between. The outer plate-shaped member 322 is fixed with its outer surface in contact with the inner surface of the battery case. An upper expansion / contraction member 33 and a lower expansion / contraction member 34 are positioned between the outer plate-shaped member 322 and the inner plate-shaped member 321.

[0031] The upper expansion / contraction member 33 is bag-shaped and expands when air is supplied to its interior and contracts when air is discharged from its interior. As shown in Figure 1, the upper expansion / contraction member 33 is positioned between the inner plate-shaped member 311 and the outer plate-shaped member 312 on the upper side of the end plate 31, and between the inner plate-shaped member 321 and the outer plate-shaped member 322 on the upper side of the end plate 32.

[0032] The lower expansion / contraction member 34 is bag-shaped and expands when air is supplied to its interior and contracts when air is discharged from its interior. The upper expansion / contraction member 33 is positioned between the inner plate-shaped member 311 and the outer plate-shaped member 312 on the underside of the end plate 31, and between the inner plate-shaped member 321 and the outer plate-shaped member 322 on the underside of the end plate 32, as shown in Figure 1.

[0033] With this configuration, when the upper expansion / contraction member 33 and the lower expansion / contraction member 34 are expanded, a reaction force is generated from the outer plate-shaped members 312 and 322 fixed to the battery case toward the inside of the battery cell stack 10, and this reaction force can provide a force that moves the inner plate-shaped members 311 and 321 toward the inside of the battery cell stack 10.

[0034] The upper air supply device 35 is a device that supplies air to the inside of the upper expansion / contraction member 33. The upper air supply device 35 includes a compressor 351, an air tank 352, an air passage 353, an on / off valve (not shown), and a safety valve 354.

[0035] The compressor 351 generates compressed air and supplies it to the air tank 352. The air tank 352 stores the compressed air supplied from the compressor 351. The air passage 353 connects the air tank 352 to the upper expansion / contraction member 33 and is a passage for supplying the air stored in the air tank 352 to the upper expansion / contraction member 33. By controlling the opening and closing of the on / off valve provided in the air passage 353, the supply of air to the upper expansion / contraction member 33 can be stopped or stopped. The upper air supply device 35 is electrically connected to the control unit 50.

[0036] The lower air supply device 36 is a device that supplies air to the inside of the lower expansion / contraction member 34. The lower air supply device 36 includes a compressor 361, an air tank 362, an air passage 363, an on / off valve (not shown), and a safety valve 364.

[0037] The compressor 361 generates compressed air and supplies it to the air tank 362. The air tank 362 stores the compressed air supplied from the compressor 361. The air passage 363 connects the air tank 362 to the lower expansion / contraction member 34 and is a passage for supplying the air stored in the air tank 362 to the lower expansion / contraction member 34. By controlling the opening and closing of the on / off valve provided in the air passage 363, the supply of air to the lower expansion / contraction member 34 can be stopped or stopped. The lower air supply device 36 is electrically connected to the control unit 50.

[0038] Figure 4 is a schematic diagram showing the pressurizing mechanism 30 in a state where the pressure on the lower side of the battery cell stack 10 is relatively high. Note that Figure 4 shows the positions of the end plates 31 and 32 if the battery cell stack 10 were not in place.

[0039] As shown in Figure 4, compared to the case shown in Figure 1, the lower expansion / contraction member 34 expands and the upper expansion / contraction member 33 contracts. As a result, compared to the case shown in Figure 1, a higher pressure is applied to the battery cell stack 10 in the stacking direction on the lower side of the battery cell stack 10, and a lower pressure is applied to the battery cell stack 10 in the stacking direction on the upper side of the battery cell stack 10. Comparing the upper expansion / contraction member 33 and the lower expansion / contraction member 34, the lower expansion / contraction member 34 expands more, so the inner plate-like members 311 and 321 tilt so that they approach the center of the battery module 1 in the stacking direction as they move from top to bottom. That is, when the battery cell stack 10 is placed between the inner plate-like members 311 and 321, a higher pressure is applied to the battery cell stack 10 on the lower side than on the upper side.

[0040] (Sensor group) The sensor group 40 consists of, for example, a temperature sensor 41 for detecting the temperature of the battery cell stack 10, a voltage sensor 42 for detecting the voltage within the battery cell stack 10, and a current sensor 43 for detecting the current within the battery cell stack 10.

[0041] Multiple temperature sensors 41 are arranged at different positions in the XZ plane. In this embodiment, two temperature sensors 41 are arranged. That is, the temperature sensors 41 are arranged at a first position in the XZ plane and at a second position different from the first position. The temperature sensors 41 may be arranged, for example, on the battery cell stack 10, or on the end plates 31 and 32 of the pressurizing mechanism 30. In this embodiment, as shown in Figure 1, they are arranged on the lower and upper sides of the end plates 31 and 32. Note that the number of temperature sensors 41 may be three or more.

[0042] Multiple voltage sensors 42 and current sensors 43 are arranged at different positions in the XZ plane. In this embodiment, two voltage sensors 42 and two current sensors 43 are arranged. That is, the voltage sensors 42 and current sensors 43 are arranged at a first position and a second position different from the first position in the XZ plane. In this embodiment, the voltage sensors 42 and current sensors 43 are arranged so that voltage and current can be detected on both the upper and lower sides of the battery cell stack 10.

[0043] The control unit 50 is a computer that controls the drive of the pressurizing mechanism 30 based on detection signals from the sensor group 40, etc.

[0044] The control unit 50 is an arithmetic unit composed of a processor, which reads various programs and data from the storage unit (not shown) and performs predetermined data processing. The processor is, for example, a CPU (central processing unit), MPU (micro processing unit), SoC (system on a chip), DSP (digital signal processor), GPU (graphics processing unit), VPU (vision processing unit), ASIC (application specific integrated circuit), PLD (programmable logic device), or FPGA (field-programmable gate array).

[0045] As shown in Figure 4, the control unit 50 includes a temperature information acquisition unit 51, a resistance information acquisition unit 52, and a pressure control unit 53.

[0046] The temperature information acquisition unit 51 acquires temperature information of the battery cells 20 based on the temperature detection value of the battery cell stack 10 detected by the temperature sensor 41. In this embodiment, the temperature information acquisition unit 51 acquires temperature detection values ​​at a first position and a second position of the battery cell stack 10. The temperature information may be, for example, the temperature at each part of the battery cell stack 10, the temperature distribution in a plane direction perpendicular to the stacking direction of the battery cell stack 10, the temperature variation, or the temperature difference between the part with the highest temperature and the part with the lowest temperature in a plane direction perpendicular to the stacking direction of the battery cell stack 10. The temperature difference may be the difference between the highest and lowest temperatures among the different temperatures of each part of the battery cell 20 in the XZ plane direction, the difference between the highest temperature among the different temperatures of each part in the XZ plane direction and the average temperature inside the battery cell 20, or the difference between the lowest temperature among the different temperatures of each part of the battery cell 20 in the XZ plane direction and the average temperature inside the battery cell 20.

[0047] The resistance information acquisition unit 52 acquires resistance information of the battery cells 20 based on the voltage value within the battery cell stack 10 detected by the voltage sensor 42 and the current value within the battery cell stack 10 detected by the current sensor 43. In this embodiment, the resistance information acquisition unit 52 acquires the detected values ​​of current and voltage at a first position and a second position within the battery cell stack 10. The resistance information may be the resistance within the battery cells 20 at each part of the battery cell stack 10, the resistance difference between the part with the highest resistance and the part with the lowest resistance in the battery cell 20 in a plane direction perpendicular to the stacking direction of the battery cell stack 10, or the variation in resistance within the battery cells 20 in a plane direction perpendicular to the stacking direction of the battery cell stack 10. The resistance difference may be the difference between the highest and lowest resistance among the resistances of each part of the battery cell 20, the difference between the highest resistance among the resistances of each part of the battery cell 20 and the average resistance of the battery cell 20, or the difference between the lowest resistance among the resistances of each part of the battery cell 20 and the average resistance of the battery cell 20. Furthermore, resistance information is information that is correlated with temperature information, and may also be information based on temperature information. That is, temperature information may be information based on resistance differences, etc., caused by temperature variations.

[0048] The temperature information acquisition unit 51 may acquire temperature information based on the resistance information acquired by the resistance information acquisition unit 52. In other words, the temperature information may be information based on resistance information generated by temperature variations.

[0049] The pressure control unit 53 can control the pressurizing mechanism 30 to apply different pressures to the pressurizing mechanism 30 depending on its position in the XZ plane. For example, the pressure control unit 53 may control the pressurizing mechanism 30 to adjust the inclination of the inner plate-like members 311 and 321 with respect to the XZ plane, thereby applying different pressures to the pressurizing mechanism 30 depending on its position in the XZ plane.

[0050] Here, the relationship between temperature, resistance, pressure, and lithium metal deposition of the battery cell 20 will be explained with reference to Figures 5A to 6B. Figure 5A is a schematic diagram showing the temperature distribution and resistance of the battery cell stack 10 when a water jacket 60, through which cooling water at a lower temperature than the battery module 1 flows, is placed on the bottom surface 11 of the battery module 1. Figure 5B shows the state in which the lower side of the battery cell stack 10 is pressurized relative to the battery module 1 shown in Figure 5A, and the resistance in that case. Figure 6A is a schematic diagram showing the temperature distribution and resistance of the battery cell stack 10 when a water jacket 60, through which water at a higher temperature than the battery module 1 flows, is placed on the bottom surface 11 of the battery module 1. Figure 6B shows the resistance when the upper side of the battery cell stack 10 is pressurized relative to the battery module 1 shown in Figure 6A. Note that (a) in Figures 5A to 6B shows the temperature distribution in the battery cell stack 10, and (b) in Figures 5A to 6B shows the resistance distribution. In Figures 5A to 6B (a), the denser the dots, the higher the temperature. Furthermore, the deposited metal D shown in Figures 5A and 6A represents the total amount of lithium metal deposited in each battery cell 20 contained within the battery cell stack 10. In these figures, the amount of lithium metal deposited is exaggerated for illustrative purposes and shown as more than the actual amount.

[0051] As shown in Figures 5A and 6A, when cooling or heating the battery cell 20, mainly one side of the battery module 1, mainly the bottom surface 11, is cooled or heated. However, because only one side is cooled or heated, temperature variations such as temperature gradients occur within the battery cell 20. Specifically, as shown in Figures 5A(a) and 6A(a), a temperature gradient occurs from the top surface 12 to the bottom surface 11 within the battery cell 20. When a temperature gradient occurs within the battery cell 20, the difference in resistance within the battery cell 20 (hereinafter referred to as cell resistance) also increases, as shown in Figures 5A(b) and 6A(b).

[0052] Because lithium ions within the battery cell 20 tend to move to the side with lower cell resistance, lithium from the negative electrode side and other areas tends to precipitate as deposited metal D on the side with lower cell resistance. As a result, variations in thickness occur in the stacking direction within the plane perpendicular to the stacking direction of the battery cell 20, and variations in surface pressure occur within the plane perpendicular to the stacking direction.

[0053] Cell resistance decreases when the stacking pressure on the battery cell 20 increases, and conversely, increases when the stacking pressure on the battery cell 20 decreases. Therefore, in areas of the battery cell stack 10 where the temperature is high (upper side in Figure 5A, lower side in Figure 6A), the stacking pressure increases further due to the deposition of lithium metal, which further decreases cell resistance, and further increases the amount of lithium metal deposited, accelerating a negative cycle that may ultimately lead to a short circuit.

[0054] To solve these problems, in this embodiment, the pressure control unit 53 controls the pressurizing mechanism 30 based on temperature information acquired by the temperature information acquisition unit 51 or resistance information acquired by the resistance information acquisition unit 52.

[0055] For example, the pressure control unit 53 may control the pressurizing mechanism 30 so that a pressure corresponding to each part is applied based on the resistance within the battery cells 20 at each part of the battery cell stack 10 indicated by the resistance information. Specifically, the pressure control unit 53 may control the pressurizing mechanism 30 so that the pressure inside the battery cells 20 increases as the resistance inside the battery cells 20 increases, and decreases as the resistance inside the battery cells 20 decreases.

[0056] Alternatively, for example, the pressure control unit 53 may control the pressurizing mechanism 30 so that pressure corresponding to each of the multiple parts is applied based on the resistance difference within the battery cell 20 in the XZ plane. Specifically, the pressure control unit 53 may control the pressurizing mechanism 30 so that the greater the resistance difference within the battery cell 20, the wider the difference between the maximum and minimum pressure applied to the battery cell 20, and the smaller the difference between the maximum and minimum pressure applied to the battery cell 20, the narrower the difference between the maximum and minimum pressure applied to the battery cell 20.

[0057] For example, the pressure control unit 53 may control the pressurizing mechanism 30 so that a pressure corresponding to each part is applied based on the temperature inside the battery cells 20 in each part of the battery cell stack 10 indicated by the temperature information. Specifically, the pressure control unit 53 may control the pressurizing mechanism 30 so that the higher the temperature inside the battery cells 20, the lower the pressure inside the battery cells 20 in the target part, and the lower the temperature inside the battery cells 20, the higher the pressure inside the battery cells 20 in the target part.

[0058] Alternatively, for example, the pressure control unit 53 may control the pressurizing mechanism 30 to apply pressure to each of several parts based on the temperature difference within the battery cell 20 in the XZ plane. Specifically, the pressure control unit 53 may control the pressurizing mechanism 30 such that the greater the temperature difference within the battery cell 20, the narrower the difference between the maximum and minimum pressure applied to the battery cell 20, and the lower the resistance difference within the battery cell 20, the wider the difference between the maximum and minimum pressure applied to the battery cell 20.

[0059] As shown in Figures 5B(a) and 6B(a), in this embodiment, the pressurizing mechanism 30 is controlled so that a relatively high pressure is applied to the side of the battery cell 20 with a higher temperature in the XZ plane, and a relatively low pressure is applied to the side with a lower temperature. As a result, as shown in Figures 5B(b) and 6B(b), the difference in cell resistance in the XZ plane is reduced, and variations in the amount of lithium metal deposited in the XZ plane can be suppressed.

[0060] For example, the pressure control unit 53 may control the pressurizing mechanism to increase the pressure applied to areas where the temperature indicated by the temperature information is higher than a predetermined threshold. The predetermined threshold may be a temperature predetermined considering the performance of the battery module 1, the average value of the temperatures of multiple battery cells 20 included in the battery cell stack 10 in the XZ plane, or the average value of the temperature of a single battery cell 20 in the XZ plane.

[0061] Here, the relationship between the temperature of the battery cell 20 and its cell resistance will be explained with reference to Figure 7. Figure 7 is a graph showing the relationship between the temperature of the battery cell 20 and its cell resistance. In Figure 7, the horizontal axis represents the temperature of the battery cell 20 (°C), and the vertical axis represents the cell resistance (mΩ). As shown in Figure 7, in the high temperature range of the battery cell 20 (around 50°C, hereinafter referred to as the high temperature range), the amount of change in cell resistance in response to temperature changes is small, and the difference in cell resistance caused by temperature differences is also small. On the other hand, in the normal temperature range of the battery cell 20 (around 30°C, hereinafter referred to as the normal temperature range), the amount of change in cell resistance in response to temperature changes is larger than in the high temperature range, and the difference in cell resistance caused by temperature differences is also larger. Furthermore, in the low temperature range of the battery cell 20 (around 10°C, hereinafter referred to as the low temperature range), the amount of change in cell resistance in response to temperature changes is even larger than in the high temperature range and the normal temperature range, and the difference in cell resistance caused by temperature differences is also even larger.

[0062] Therefore, in this embodiment, the pressure control unit 53 may control the pressurizing mechanism 30 such that the higher the temperature of the battery cell stack 10, the smaller the pressure difference applied to each of the multiple parts in the XZ plane, and the lower the temperature of the battery cell stack 10, the larger the pressure difference applied to each of the multiple parts in the XZ plane. This allows pressure in the stacking direction to be applied to the battery cells 20 in areas where the difference in cell resistance due to temperature changes is large, in order to compensate for the large resistance difference caused by the temperature change, and pressure corresponding to the resistance difference can be applied to areas where the resistance difference is small. Even if the precise temperature of each part of the battery cell stack 10 and the battery cells 20 cannot be detected, the resistance of the battery cells 20 and the entire battery cell stack 10 in the XZ plane can be efficiently equalized.

[0063] In this specification, the temperature of the battery cell stack 10 may be the average value of the temperatures of the multiple battery cells 20 constituting the battery cell stack 10, the temperature of the highest battery cell 20 among the multiple battery cells 20 constituting the battery cell stack 10, or the temperature of the lowest battery cell 20 among the multiple battery cells 20 constituting the battery cell stack 10. Furthermore, in this specification, the temperature of the multiple battery cells 20 may be the average value of the highest temperature of the multiple battery cells 20 at multiple locations of each battery cell 20 in the XZ plane, the average value of the lowest temperature of the multiple battery cells 20 at multiple locations of each battery cell 20 in the XZ plane, or the average value of the average temperature of the multiple battery cells 20 at multiple locations of each battery cell 20 in the XZ plane.

[0064] Next, a modified version of the pressurizing mechanism 30 will be described. In each modified version, the characteristic configuration will be described, and components that have the same configuration and function as the pressurizing mechanism 30 of the above embodiment will be given the same reference numerals as those used in Figures 1 and 4 for the pressurizing mechanism 30, and their detailed descriptions will be omitted.

[0065] First, the pressurizing mechanism 30A relating to the first modified example will be explained with reference to Figures 8A to 8C.

[0066] The pressurizing mechanism 30A includes a pair of end plates 31 and 32, an upper expandable member 33A, and a lower expandable member 34A. The pressurizing mechanism 30A of the first modified example differs from the pressurizing mechanism 30 in that it does not include an upper expandable / contractible member 33, a lower expandable / contractible member 34, an upper air supply device 35, and a lower air supply device 36, but instead includes an upper expandable / contractible member 33A and a lower expandable / contractible member 34A. Note that the end plate 31 and the upper expandable / contractible member 33A and lower expandable / contractible member 34A located on the end plate 31 side are not shown in Figures 8A to 8C.

[0067] The upper expandable member 33A is positioned between the inner plate-shaped member 311 and the outer plate-shaped member 312 on the upper side of the end plate 31, and between the inner plate-shaped member 321 and the outer plate-shaped member 322 on the upper side of the end plate 32. As shown in Figures 8A to 8C, the upper expandable member 33A positioned on the end plate 32 is positioned to extend from the surface of the outer plate-shaped member 322 on the battery cell stack 10 side to the inner plate-shaped member 321, and can expand and contract in the stacking direction by a control signal from the control unit 50. The upper expandable member 33A positioned on the end plate 31 has the same configuration as the upper expandable member 33A positioned on the end plate 32.

[0068] The lower expandable member 34A is positioned between the inner plate-shaped member 311 and the outer plate-shaped member 312 on the underside of the end plate 31, and between the inner plate-shaped member 321 and the outer plate-shaped member 322 on the underside of the end plate 32. As shown in Figures 8A to 8C, the lower expandable member 34A positioned on the end plate 32 is positioned to extend from the surface of the outer plate-shaped member 322 facing the battery cell stack 10 to the inner plate-shaped member 321, and can expand and contract in the stacking direction by a control signal from the control unit 50. The lower expandable member 34A positioned on the end plate 31 has the same configuration as the lower expandable member 34A positioned on the end plate 32.

[0069] With this configuration, when the upper expandable member 33A and the lower expandable member 34A are extended toward the battery cell stack 10, the inner plate-like members 311 and 321 are pushed by the upper expandable member 33A and the lower expandable member 34A. In other words, a force can be applied to the inner plate-like members 311 and 321 to move toward the inside of the battery cell stack 10.

[0070] In Figure 8A, the upper expandable member 33A does not extend further toward the battery cell stack 10 than the lower expandable member 34A, and the battery cell stack 10 is not positioned between the end plates 31 and 32. In this state, the lower side of the inner plate-like member 321 is inclined inward toward the battery module 1 with respect to the XZ plane. As a result, when the battery cell stack 10 is positioned between the end plates 31 and 32, a high pressure is applied to the battery cells 20 in the stacking direction on the lower side of the battery cell stack 10, and a lower pressure is applied to the upper side of the battery cell stack 10 compared to the lower side.

[0071] In Figure 8B, the upper expandable member 33A and the lower expandable member 34A extend approximately equally toward the battery cell stack 10, and the inner plate-like member 321 is positioned without approximately inclination with respect to the XZ plane when the battery cell stack 10 is not positioned between the end plates 31 and 32.

[0072] In Figure 8C, the upper expandable member 33A extends further toward the battery cell stack 10 than the lower expandable member 34A, and when the battery cell stack 10 is not positioned between the end plates 31 and 32, the upper side of the inner plate-like member 321 is inclined inward toward the battery module 1 with respect to the XZ plane. As a result, when the battery cell stack 10 is positioned between the end plates 31 and 32, a high pressure is applied to the battery cells 20 in the stacking direction on the upper side of the battery cell stack 10, and a lower pressure is applied to the lower side of the battery cell stack 10 compared to the upper side.

[0073] In the first modified example, the upper expandable member 33A and lower expandable member 34A of the pressurizing mechanism 30A have their expansion and contraction in the stacking direction controlled based on temperature information or resistance information of multiple different parts of the battery cell 20 in the XZ plane. Specifically, the control unit 50 controls the pressurizing mechanism 30A based on temperature information or resistance information so that a force is applied to the inner plate-like members 311 and 321 in a direction that changes the inclination of the inner plate-like members 311 and 321 with respect to the XZ plane, thereby applying different pressures depending on the position in the XZ plane.

[0074] Next, the pressurizing mechanism 30B relating to the second modified example will be explained with reference to Figures 9A to 9D.

[0075] The pressurizing mechanism 30B includes a pair of end plates 31 and 32, an upper movable shaft 33B, and a lower movable shaft 34B. The pressurizing mechanism 30B of the second modified example differs from the pressurizing mechanism 30B in that it does not include an upper expansion / contraction member 33, a lower expansion / contraction member 34, an upper air supply device 35, and a lower air supply device 36, but instead includes an upper movable shaft 33B and a lower movable shaft 34B. Note that the end plate 31 and the upper movable shaft 33B and lower movable shaft 34B located on the end plate 31 side are not shown in Figures 9A to 9D.

[0076] The upper movable shaft 33B and the lower movable shaft 34B are cylindrical members that extend in the width direction of the battery module 1. The upper movable shaft 33B and the lower movable shaft 34B are positioned between the inner plate-like member 311 and the outer plate-like member 312 in the end plate 31, and between the inner plate-like member 321 and the outer plate-like member 322 in the end plate 32, and are movable in the height direction based on control signals from the control unit 50. The upper movable shaft 33B is positioned above the lower movable shaft 34B.

[0077] As shown in Figure 9A, when both the upper movable shaft 33B and the lower movable shaft 34B are positioned on the lower side, the lower side of the inner plate-like member 321 is tilted inward of the battery module 1 with respect to the XZ plane, when the battery cell stack 10 is not positioned between the end plates 31 and 32.

[0078] As shown in Figure 9B, when the upper movable shaft 33B moves further upward from the state shown in Figure 9A, the lower side of the inner plate-like member 321 tilts further inward toward the battery module 1 with respect to the XZ plane.

[0079] As shown in Figure 9C, when the upper movable shaft 33B is positioned above the end plate 32 and the lower movable shaft 34B is positioned below the end plate 32, the inner plate-like member 321 is positioned with virtually no inclination with respect to the XZ plane.

[0080] As shown in Figure 9D, when the lower movable shaft 34B moves further upward from the state shown in Figure 9C, the lower side of the inner plate-like member 321 tilts outward with respect to the XZ plane, and the upper side tilts inward with respect to the battery module 1.

[0081] In the second modified example, the upper movable shaft 33B and the lower movable shaft 34B of the pressurizing mechanism 30B are controlled in the height direction based on temperature information or resistance information of multiple different parts of the battery cell 20 in the XZ plane. Specifically, the control unit 50 controls the pressurizing mechanism 30B based on temperature information or resistance information so that a force is applied to the inner plate-like members 311 and 321 in a direction that changes the inclination of the inner plate-like members 311 and 321 with respect to the XZ plane, thereby applying different pressures depending on the position in the XZ plane.

[0082] Next, the pressurizing mechanism 30C relating to the third modified example will be explained with reference to Figures 10A and 10B.

[0083] The pressurizing mechanism 30C includes a pair of end plates 31 and 32, an upper sliding mechanism 33C, and a lower sliding mechanism 34C. The pressurizing mechanism 30C of the third modified example differs from the pressurizing mechanism 30 in that it does not include an upper expansion / contraction member 33, a lower expansion / contraction member 34, an upper air supply device 35, and a lower air supply device 36, but instead includes an upper sliding mechanism 33C and a lower sliding mechanism 34C. Note that the end plate 31 and the upper sliding mechanism 33C and lower sliding mechanism 34C located on the end plate 31 side are not shown in Figures 10A and 10B.

[0084] The upper sliding mechanism 33C and the lower sliding mechanism 34C are positioned between the inner plate-shaped member 311 and the outer plate-shaped member 312 in the end plate 31, and between the inner plate-shaped member 321 and the outer plate-shaped member 322 in the end plate 32, and are movable in the height direction based on control signals from the control unit 50. The upper sliding mechanism 33C is positioned above the lower sliding mechanism 34C.

[0085] The upper sliding mechanism 33C is located on the inner plate-shaped members 311 and 321 side and includes a rod-shaped member 331 extending in the width direction of the battery module 1, and a support portion 332 located on the outer plate-shaped members 312 and 322 side and supporting the rod-shaped member 331. The support portion 332 is configured to slide along the outer plate-shaped member 312 or the outer plate-shaped member 322 in the height direction.

[0086] The lower sliding mechanism 34C is located on the inner plate-shaped members 311 and 321 side and includes a rod-shaped member 341 extending in the width direction of the battery module 1, and a support portion 342 located on the outer plate-shaped members 312 and 322 side and supporting the rod-shaped member 341. The support portion 342 is configured to slide in the height direction along the outer plate-shaped member 312 or the outer plate-shaped member 322.

[0087] For example, as shown in Figure 10A, when the upper sliding mechanism 33C is positioned above the end plate 32 and the lower sliding mechanism 34C is positioned below the end plate 32, the inner plate-like member 321 is positioned with virtually no inclination with respect to the XZ plane.

[0088] For example, as shown in Figure 10B, when the lower sliding mechanism 34C moves further upward from the state shown in Figure 10A, the lower side of the inner plate-shaped member 321 tilts outward with respect to the XZ plane, and the upper side tilts inward with respect to the battery module 1.

[0089] In the third modified example, the upper sliding mechanism 33C and lower sliding mechanism 34C of the pressurizing mechanism 30C are controlled in the height direction based on temperature information or resistance information of multiple different parts of the battery cell 20 in the XZ plane. Specifically, the control unit 50 controls the pressurizing mechanism 30C based on temperature information or resistance information so that a force is applied to the inner plate-like members 311 and 321 in a direction that changes the inclination of the inner plate-like members 311 and 321 with respect to the XZ plane, thereby applying different pressures depending on the position in the XZ plane.

[0090] The battery module 1 according to this embodiment, as described above, provides the following effects.

[0091] The battery module 1 according to this embodiment comprises a battery cell 20 which is a laminate having a positive electrode layer 21, a negative electrode layer 22, and a solid electrolyte layer 23 located between the positive electrode layer 21 and the negative electrode layer 22, and includes pressurizing mechanisms 30, 30A, 30B, and 30C that apply pressure to the battery cell 20 from both sides in the stacking direction of the laminate and apply different pressures depending on the position in the planar direction perpendicular to the stacking direction of the laminate, and a control unit 50 that controls the pressurizing mechanisms 30, 30A, 30B, and 30C based on temperature information relating to the temperature of the battery cell 20 at multiple locations where the battery cell 20 is located in different planar directions, so that a pressure corresponding to the temperature information of each of the multiple locations is applied to each of the multiple locations.

[0092] As a result, since the resistance within the battery cell 20 tends to decrease as the temperature of the battery cell 20 increases, pressure can be applied to each part in the planar direction perpendicular to the stacking direction of the battery cell 20 according to their temperature information, thereby reducing the resistance difference within the battery cell 20 in the planar direction perpendicular to the stacking direction due to temperature variations. Therefore, the deposition of lithium metal in the planar direction perpendicular to the stacking direction of the battery cell due to charging and discharging can be made more uniform.

[0093] Furthermore, in the battery module 1 according to this embodiment, a plurality of battery cells 20 are stacked in the stacking direction to form a battery cell stack 10, and the pressurizing mechanisms 30, 30A, 30B, and 30C have a pair of inner plate-like members 311 and 321 provided at both ends of the battery cell stack 10 in the stacking direction, and the pressure control unit 50 controls the pressurizing mechanisms 30, 30A, 30B, and 30C so that a force is applied to the pair of plate-like members 311 and 321 in a direction that changes the inclination of the pair of inner plate-like members 311 and 321 with respect to the plane direction, thereby applying different pressures to the pressurizing mechanisms 30, 30A, 30B, and 30C according to their position in the XZ plane direction.

[0094] This allows for the application of different pressures depending on the position in the plane direction perpendicular to the stacking direction of the battery cell 20, using a simpler configuration.

[0095] Furthermore, in the battery module 1 according to this embodiment, the pressure control unit 50 controls the pressurizing mechanisms 30, 30A, 30B, and 30C so as to reduce the pressure applied to parts where the temperature indicated by the temperature information is higher than a predetermined threshold, and increase the pressure applied to parts where the temperature indicated by the temperature information is lower than a predetermined threshold.

[0096] This allows for a more reliable reduction of resistance variations within the battery cell 20 and equalization of lithium metal deposition in the planar direction perpendicular to the stacking direction of the battery cell 20.

[0097] Furthermore, in the battery module 1 according to this embodiment, the temperature information is the temperature variation in the planar direction of the battery cell, and the control unit 50 adjusts the pressure applied to each of the multiple parts based on the resistance difference within the battery cell 20 caused by the temperature variation in the XZ plane direction of the battery cell 20.

[0098] This allows for more reliable equalization of resistance within the battery cell 20.

[0099] Furthermore, in the battery module 1 according to this embodiment, multiple battery cells 20 are stacked in the stacking direction to form a battery cell stack 10, and the control unit 50 controls the pressurizing mechanisms 30, 30A, 30B, and 30C so that the higher the temperature of the battery cell stack 10, the greater the pressure difference applied to each of the multiple parts in the XZ plane direction, and the lower the temperature of the battery cell stack 10, the smaller the pressure difference in the XZ plane direction of the battery cell stack 10.

[0100] This allows for the application of pressure in the stacking direction to the battery cells 20 in areas where the difference in cell resistance due to temperature changes is large, thereby compensating for the large resistance difference caused by the temperature change, and applying pressure corresponding to the resistance difference to areas where the resistance difference is small. Even when it is not possible to accurately detect the temperature of each part of the battery cell stack 10 or the battery cells 20, the resistance of the entire battery cell stack 10 and battery cell stack 10 in the XZ plane can be efficiently equalized.

[0101] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified as appropriate without impairing the spirit of the invention.

[0102] In the above embodiment, the battery cell stack 10 was comprised of multiple battery cells 20, but it may also be composed of a single battery cell 20. [Explanation of Symbols]

[0103] 1 Battery Module 10 Battery cell stack 20 battery cells 21 Positive electrode layer 22 Negative electrode layer 23 Solid electrolyte layer 30, 30A, 30B, 30C Pressurization mechanism 50 Control Unit 53 Pressure Control Unit

Claims

1. A battery module comprising a battery cell which is a laminate having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer, A pressurizing mechanism that applies pressure to the battery cells from both sides in the stacking direction of the laminate, and that can apply different pressures depending on the position in the plane direction perpendicular to the stacking direction of the laminate, A battery module comprising: a pressure control unit that controls the pressurizing mechanism based on temperature information relating to the temperature of the battery cell at multiple locations of the battery cell at different positions in the planar direction, so that a pressure corresponding to the temperature information of each of the multiple locations is applied to each of the multiple locations.

2. Multiple battery cells are stacked in the stacking direction to form a battery cell stack. The pressurizing mechanism comprises a pair of plate-shaped members provided at both ends of the battery cell stack in the pre-stacking direction, The battery module according to claim 1, wherein the pressure control unit controls the pressurizing mechanism so that a force is applied to the pair of plate-like members in a direction that changes the inclination of the pair of plate-like members with respect to the surface direction, thereby applying different pressures to the pressurizing mechanism according to the position in the surface direction.

3. The pressure control unit reduces the pressure applied to areas where the temperature indicated by the temperature information is higher than a predetermined threshold. The battery module according to claim 1, wherein the pressurizing mechanism is controlled to increase the pressure applied to a part where the temperature indicated by the temperature information is lower than a predetermined threshold.

4. The temperature information is the temperature variation of the battery cell in the plane direction, The battery module according to claim 1, wherein the pressure control unit adjusts the pressure applied to each of the plurality of parts based on the resistance difference within the battery cell caused by temperature variations in the planar direction of the battery cell.

5. Multiple battery cells are stacked in the stacking direction to form a battery cell stack. The battery module according to claim 1, wherein the pressure control unit controls the pressurizing mechanism such that the pressure difference applied to each of the plurality of portions in the planar direction of the battery cell stack increases as the temperature of the battery cell stack increases, and the pressure difference decreases as the temperature of the battery cell stack decreases.

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