Power storage device

Abstract

To provide a power storage device capable of suppressing application of an excessive load to a battery cell at the time of expansion of the battery cell.SOLUTION: A power storage device according to the present invention includes: a battery module in which a plurality of battery cells are stacked; a plurality of elastic members that apply a restraining load in a stacking direction of the plurality of battery cells; a plate disposed between the battery cells and the elastic members so as to be movable in the stacking direction; and a pressure sensor provided on the plate. At least one of the plurality of elastic members is in contact with the plate in the stacking direction, and includes an elastic member contracting mechanism that contracts the elastic member in contact with the plate when a value output by the pressure sensor in a state where the plate is sandwiched between the battery cell and the elastic member becomes equal to or greater than a threshold value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device. [Background technology]

[0002] Patent Document 1 discloses an electricity storage device equipped with a switching device that can switch the restraint load that restrains a plurality of battery cells in the stacking direction when the battery cells contract. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-114625 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electricity storage device disclosed in Patent Document 1, there is a risk that an excessive load will be applied to the battery cells if the battery cells deteriorate and expand.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide an electricity storage device that can prevent excessive load from being applied to battery cells when the battery cells expand. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the storage device of the present invention is a storage device comprising: a battery module in which a plurality of battery cells are stacked; a plurality of elastic members that apply a restraint load in the stacking direction of the plurality of battery cells; a plate that is arranged between the battery cells and the elastic members and is movable in the stacking direction; and a pressure sensor provided on the plate, wherein at least one of the plurality of elastic members is in contact with the plate in the stacking direction, and is characterized by comprising an elastic member contraction mechanism that contracts the elastic member in contact with the plate when the value output by the pressure sensor when the plate is sandwiched between the battery cell and the elastic member becomes equal to or greater than a threshold value. [Effects of the Invention]

[0007] The electricity storage device according to the present invention has an advantage in that it is possible to prevent excessive load from being applied to the battery cells when the battery cells expand. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a power storage device according to an embodiment. [Figure 2] FIG. 2 is a diagram showing a state in which the battery cells of the power storage device according to the embodiment are expanded. [Figure 3] FIG. 3 is a diagram showing a state in which the first elastic member of the power storage device according to the embodiment is contracted. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the power storage device according to the present invention will be described, but the present invention is not limited to the embodiment.

[0010] FIG. 1 is a diagram showing a schematic configuration of a power storage device 1 according to an embodiment. The power storage device 1 according to the embodiment is, for example, a battery pack mounted on an electric vehicle, and serves as a power supply source that supplies power to a motor that is a drive source of the electric vehicle. The power storage device 1 according to the embodiment includes a battery module 2, a pair of end plates 31, 32 (a first end plate 31 and a second end plate 32), a pressure sensor 4, and a load-applying device 5. The battery module 2 is configured by stacking a plurality of battery cells 20. A first end plate 31 and a second end plate 32 are provided on both ends of the battery module 2 in the stacking direction of the plurality of battery cells 20, sandwiching the plurality of battery cells 20 therebetween. The first end plate 31 and the second end plate 32 have a plate-like shape and are made of, for example, metal. The second end plate 32 is provided with a pressure sensor 4 that detects the load applied to the second end plate 32 from the battery module 2 (the plurality of battery cells 20).

[0011] The load-applying device 5 applies a restraint load to the battery module 2 (plurality of battery cells 20) in the stacking direction. The load-applying device 5 includes a holding plate 50, a plurality of elastic members 61, 62, 63 (first elastic member 61, second elastic member 62, and third elastic member 63), a plurality of individual packaging bags 71, 72, 73 (first individual packaging bag 71, second individual packaging bag 72, and third individual packaging bag 73), and a plurality of chemical needles 81, 82 (first chemical needle 81 and second chemical needle 82). The load-applying device 5 is disposed on the second end plate 32 side of the battery module 2 in the stacking direction. The second end plate 32 is disposed between the load-applying device 5 (plurality of elastic members 61, 62, 63) and the battery module 2 (battery cells 20) in the stacking direction so as to be movable along the stacking direction. The holding plate 50 is disposed on the opposite side of the plurality of elastic members 61, 62, 63 from the side on which the second end plate 32 is located in the stacking direction. The holding plate 50 is connected to the first end plate 31 by a restraining band (not shown).

[0012] The first elastic member 61, the second elastic member 62, and the third elastic member 63 have the same elastic force and are provided between the second end plate 32 and the holding plate 50 in the stacking direction. The first elastic member 61, the second elastic member 62, and the third elastic member 63 are arranged in this order from top to bottom in the height direction of the battery module 2. The ends of the first elastic member 61, the second elastic member 62, and the third elastic member 63 in the stacking direction are fixed and held by the holding plate 50. The lengths of the first elastic member 61, the second elastic member 62, and the third elastic member 63 in the stacking direction increase in this order. That is, the first elastic member 61 is the longest, followed by the second elastic member 62, and the third elastic member 63, and the shortest.

[0013] At least one of the first elastic member 61, the second elastic member 62, and the third elastic member 63 contacts the second end plate 32 via at least one of the first packaging bag 71, the second packaging bag 72, and the third packaging bag 73, which will be described later. Specifically, in the initial state of the energy storage device 1, where no deterioration of the battery cells 20 has occurred, only the first elastic member 61 is arranged to contact the second end plate 32 via the first packaging bag 71, and the second elastic member 62 and the third elastic member 63 are not in contact with the second end plate 32. The first elastic member 61, the second elastic member 62, and the third elastic member 63 can be made of a material that has resilience and can be dissolved by chemicals, such as high-resilience urethane or nitrile rubber.

[0014] First elastic member 61, second elastic member 62, and third elastic member 63 are individually covered by first individual packaging bag 71, second individual packaging bag 72, and third individual packaging bag 73, each of which has high chemical resistance. Of first elastic member 61, second elastic member 62, and third elastic member 63, first chemical needle 81 and second chemical needle 82 are inserted into first elastic member 61 and second elastic member 62, respectively. First chemical needle 81 and second chemical needle 82 constitute an elastic member contraction mechanism that can selectively inject chemical into first elastic member 61 or second elastic member 62 from first chemical needle 81 or second chemical needle 82, for example, by actuating a cylinder not shown in response to an electrical signal from a control device not shown. The control device may be provided in power storage device 1 or in a vehicle in which power storage device 1 is mounted. The chemicals injected from the first chemical needle 81 and the second chemical needle 82 into the first elastic member 61 and the second elastic member 62 contain a substance that can dissolve the first elastic member 61 and the second elastic member 62.

[0015] Here, the distance between the pair of end plates 31, 32 in the stacking direction in the initial state of the energy storage device 1 shown in FIG. 1 when no deterioration of the battery cells 20 has occurred is defined as L1. The distance between the second end plate 32 and the holding plate 50 in the stacking direction in the initial state of the energy storage device 1 is defined as L21. The distance between the first end plate 31 and the holding plate 50 in the stacking direction in the initial state of the energy storage device 1 is defined as L1, which is the sum of the distance L1 between the pair of end plates 31, 32 in the stacking direction, the thickness of the second end plate 32, and the distance L21 between the second end plate 32 and the holding plate 50 in the stacking direction. In the initial state of the energy storage device 1 shown in FIG. 1, the value output by the pressure sensor 4 as the load applied from the battery module 2 (plurality of battery cells 20) to the second end plate 32 is defined as load F1.

[0016] Fig. 2 is a diagram showing a state in which a battery cell 20 of the energy storage device 1 according to the embodiment has expanded. In the energy storage device 1 shown in Fig. 2, at least one of the plurality of battery cells 20 has expanded due to deterioration, and a load F2 greater than the load F1 is applied from the battery module 2 (the plurality of battery cells 20) to the second end plate 32, causing the second end plate 32 to move toward the holding plate 50 in the stacking direction.

[0017] 2, the distance between the pair of end plates 31, 32 in the stacking direction is L12, which is wider than the distance L11 in the initial state of the energy storage device 1. When the battery cells 20 have expanded in the stacking direction due to deterioration, the distance between the second end plate 32 and the holding plate 50 in the stacking direction is L22, which is narrower than the distance L21 in the initial state of the energy storage device 1. When the battery cells 20 have expanded in the stacking direction, the distance between the first end plate 31 and the holding plate 50 in the stacking direction is L1, which is the same as the distance L1 in the initial state of the energy storage device 1. When the battery cells 20 have expanded in the stacking direction as shown in FIG. 2, the value output by the pressure sensor 4 as the load acting on the second end plate 32 from the battery module 2 (plurality of battery cells 20) is a load F2, which is higher than the load F1 in the initial state of the energy storage device 1.

[0018] In the energy storage device 1 according to the embodiment, when the second end plate 32 is sandwiched between the battery module 2 (battery cell 20) and one of the plurality of elastic members 61, 62, 62, and the value output by the pressure sensor 4 becomes equal to or greater than a preset threshold value F0, a chemical 9 is injected from the first chemical needle 81 or the second chemical needle 82 constituting the elastic member contraction mechanism into the elastic member in contact with the second end plate 32, causing it to contract.

[0019] In the energy storage device 1 shown in FIG. 2, when the second end plate 32 is sandwiched between the battery module 2 (battery cells 20) and the first elastic member 61, and the load applied to the second end plate 32 from the battery module 2 (plurality of battery cells 20) detected by the pressure sensor 4 exceeds a preset threshold value F0 (load F2≧threshold value F0>load F1), an electrical signal from the control device activates a cylinder (not shown), and chemical 9 is injected from the first chemical needle 81 into the first elastic member 61.

[0020] 3 is a diagram showing a state in which the first elastic member 61 of the energy storage device 1 according to the embodiment has been contracted. In the energy storage device 1 shown in FIG. 3, the first elastic member 61 into which the chemical 9 has been injected through the first chemical needle 81 is dissolved or otherwise contracted, and the second end plate 32 moves toward the holding plate 50 in the stacking direction, so that the second elastic member 62 comes into contact with the second end plate 32 via the second individual packaging bag 72.

[0021] Here, when the first elastic member 61 is contracted as shown in FIG. 3 , the distance in the stacking direction between the pair of end plates 31, 32 is L13, which is wider than the distance L12 before the first elastic member 61 was contracted. When the first elastic member 61 is contracted, the distance in the stacking direction between the second end plate 32 and the holding plate 50 is L23, which is narrower than the distance L22 before the first elastic member 61 was contracted. When the first elastic member 61 is contracted, the distance in the stacking direction between the first end plate 31 and the holding plate 50 is L1, which is the same as the initial state of the energy storage device 1. When the battery cells 20 are expanded in the stacking direction as shown in FIG. 3 , the value output by the pressure sensor 4 as the load acting on the second end plate 32 from the battery module 2 (the plurality of battery cells 20) is a load F3, which is lower than the load F2 before the first elastic member 61 was contracted.

[0022] In the energy storage device 1 according to the embodiment, when the battery cells 20 expand in the stacking direction due to deterioration, the elastic member in contact with the second end plate 32 contracts to reduce the restraining load, and the second end plate 32 moves to the opposite side of the battery cells 20 in the stacking direction, thereby allowing the expansion of the battery cells 20 to be appropriately released. As a result, in the energy storage device 1 according to the embodiment, the application of an excessive load to the battery cells 20 can be suppressed, and the load applied to the battery cells 20 can be kept within a certain range, thereby suppressing a decrease in performance due to a decrease in the circulation of electrolyte inside the battery cells 20.

[0023] Furthermore, in the energy storage device 1 according to this embodiment, deterioration of the battery cells 20 can be detected by detecting information relating to which of the multiple elastic members 61, 62, 63 is functioning (which is in contact with the second end plate 32). As a method for detecting deterioration of the battery cells 20, for example, the control device can detect deterioration of the battery cells 20 by counting the number of times an electrical signal is issued in response to a chemical injection command to inject the chemical 9 from the first chemical needle 81 or the second chemical needle 82 into the first elastic member 61 or the second elastic member 62. [Explanation of symbols]

[0024] 1. Energy storage device 2 Battery Module 4 Pressure Sensors 5 Load application device 9. Medicines 20 battery cells 31 First end plate 32 Second end plate 61 First elastic member 62 Second elastic member 63 Third elastic member 71 First individual packaging 72 Second individual packaging 73 Third individual packaging 81 First Medicine Needle 82 Second medicine needle

Claims

[Claim 1] a battery module in which a plurality of battery cells are stacked; a plurality of elastic members that apply a restraint load in a stacking direction of the plurality of battery cells; a plate disposed between the battery cell and the elastic member so as to be movable in the stacking direction; a pressure sensor provided on the plate; A power storage device comprising: At least one of the plurality of elastic members is in contact with the plate in the stacking direction, an elastic member contraction mechanism that contracts the elastic member in contact with the plate when the value output by the pressure sensor becomes equal to or greater than a threshold value while the plate is sandwiched between the battery cell and the elastic member.

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