Battery pack

Abstract

To prevent short circuits between adjacent battery stacks caused by debris released from battery cells. [Solution] A battery pack comprising a battery stack in which multiple battery cells are stacked, a case for housing the multiple battery stacks, and a heat insulating material positioned above the battery stack inside the case, wherein the heat insulating material has a guide portion that covers the entire battery stack in the width direction of the battery cells and extends beyond the battery cells, and ends on both sides in the width direction of the battery cells that form the lower end of the guide portion, the guide portion is inclined to move downward as it approaches one of the ends on both sides, guiding debris attached to the guide portion to the end, and at least one of the ends on both sides is located between adjacent battery stacks in the width direction of the battery cells.

Description

Technical Field

[0001] The present invention relates to a battery pack.

Background Art

[0002] Patent Document 1 discloses a battery pack including a battery module in which a plurality of battery cells are stacked and a case that houses the battery module, the battery pack including a heat insulating material disposed above the battery module and an insulator disposed above a smoke exhaust port of the battery cells.

Prior Art Documents

Patent Documents

[0003] <{

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration described in Patent Document 1, since the heat insulating material spreads in the horizontal direction, it is impossible to control the falling position of the debris after the debris released from the smoke exhaust port of the battery cell adheres to the heat insulating material. Therefore, if the debris falls so as to connect adjacent battery stacks, there is a risk that the adjacent battery stacks will be short-circuited by the debris.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery pack capable of preventing a short circuit between adjacent battery stacks due to debris released from battery cells.

Means for Solving the Problems

[0006] The present invention relates to a battery pack comprising: a battery stack in which a plurality of battery cells are stacked; a case for housing a plurality of the battery stacks arranged side by side in the width direction of the battery cells; and an insulating material disposed above the battery stacks inside the case and receiving high-temperature gas and debris released from the exhaust valves of the battery cells, wherein the insulating material has a guide portion that covers the entire battery stack in the width direction of the battery cells and extends outward from the battery cells, and ends that form the lower end of the guide portion and on both sides in the width direction of the battery cells, wherein the guide portion is inclined or curved so as to approach one of the ends on both sides to approach one of them, guiding the debris adhering to the guide portion to the end, and at least one of the ends on both sides is located between adjacent battery stacks in the width direction of the battery cells. [Effects of the Invention]

[0007] This invention makes it possible to prevent short circuits between adjacent battery stacks caused by debris released from battery cells. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing a battery pack in an embodiment. [Figure 2] This diagram illustrates the location where debris released from battery cells falls when it adheres to the insulation material. [Figure 3] This is a schematic diagram showing a modified example of an insulating material. [Figure 4] This is a schematic diagram showing another modified example of insulation material. [Modes for carrying out the invention]

[0009] The following describes in detail the battery pack in the embodiments of the present invention. However, the present invention is not limited to the embodiments described below.

[0010] Figure 1 is a schematic diagram showing a battery pack in an embodiment. The battery pack 1 is installed in electric vehicles such as hybrid vehicles and electric vehicles. The battery pack 1 stores the electricity used to drive the electric vehicle. The battery pack 1 comprises a battery stack 2 in which multiple battery cells are stacked, a case 3 that houses the battery stack 2, and an insulating material 4 provided inside the case 3.

[0011] Battery stack 2 is a battery pack in which multiple battery cells are electrically connected in series. The battery cells are rectangular cells with a rectangular prism-shaped housing, and terminals are provided on the top surface of the housing. The battery cells are composed of lithium-ion batteries. Battery stack 2 has a stack in which multiple battery cells are stacked in a first direction. The first direction is the same direction as the X direction, and is the thickness direction of the battery cells and the stacking direction of the stack. Adjacent battery cells in the first direction are electrically connected by busbars. Between adjacent battery cells in the first direction, the negative terminal of one battery cell and the positive terminal of the other battery cell are connected by busbars.

[0012] Case 3 is a battery pack case that houses multiple battery stacks 2. Case 3 is a metal case. Inside Case 3 are multiple battery stacks 2 arranged in a second direction. The second direction is perpendicular to the first direction and is the same direction as the Y direction. The second direction is the width direction of the battery cells and the width direction of the battery stacks 2. In the second direction, adjacent battery stacks 2 are spaced apart from each other.

[0013] Case 3 comprises a lower case 11 and an upper cover 12. The lower case 11 is a case formed with an open top, forming a housing chamber for the battery stack 2. The upper cover 12 is attached to the lower case 11 so as to close the opening of the lower case 11. The lower case 11 and the upper cover 12 are integrated by bolt fastening.

[0014] The surface of the upper cover 12 is coated with cationic electrodeposition paint as a rust-preventive coating. In order to prevent the self-ignition of the cationic material used as the electrodeposition coating on the upper cover 12, it is undesirable for the upper cover 12 to be directly exposed to high-temperature gases or high-temperature debris. Debris is conductive, and if it connects adjacent battery stacks 2, there is a risk that the adjacent battery stacks 2 will become electrically connected by the debris. Therefore, it is undesirable for debris to fall in a way that connects the battery stacks 2. Accordingly, the battery pack 1 is configured to prevent debris from falling in a way that connects adjacent battery stacks 2 while avoiding direct exposure of the upper cover 12 to high-temperature gases and debris.

[0015] The insulation material 4 is positioned above the battery stack 2 inside the case 3 and is a component that receives high-temperature gas and debris released from the exhaust valve provided on the top surface of the battery cell housing. The insulation material 4 is a component that protects the upper cover 12 from gas and debris released from the battery cell. The battery cell is a lithium-ion battery, and when a lithium-ion battery experiences thermal runaway, high-temperature gas and conductive debris are released from the exhaust valve of the battery cell.

[0016] The insulation material 4 is formed in a roof-like structure that completely covers the battery stack 2. The insulation material 4 is attached to the upper cover 12. The insulation material 4 is positioned above each battery stack 2. The insulation material 4 has a guide portion 21 and an end portion 22.

[0017] The guide portion 21 is inclined with respect to the horizontal direction and guides debris attached to the guide portion 21 to the end portion 22. The guide portion 21 covers the entire battery stack 2 in the second direction and extends beyond the battery cells in the second direction. The guide portion 21 is inclined to move downward as it approaches one of the two end portions 22.

[0018] The end portion 22 is the end portions on both sides in the second direction and forms the lower end of the guide portion 21. At least one of the end portions 22 on both sides is located between adjacent battery stacks 2 in the second direction. The end portion 22 is located below the upper surface of the battery cell in the vertical direction.

[0019] For example, the roof-shaped heat insulating material 4 includes a flat first roof member 31 and a flat second roof member 32. The first roof member 31 and the second roof member 32 are joined and integrated. The first roof member 31 inclines downward as it goes from the center side of the battery stack 2 toward one side in the Y direction. The second roof member 32 inclines downward as it goes from the center side of the battery stack 2 toward the other side in the Y direction. The second roof member 32 inclines to the opposite side of the first roof member 31 with respect to the Y direction.

[0020] As shown in FIG. 2, when the battery cell undergoes thermal runaway, the gas generated inside the battery cell is discharged from the smoke exhaust valve, and the gas and debris hit the roof-shaped heat insulating material 4. The debris hitting the heat insulating material 4 falls from the heat insulating material 4 onto the upper surface of the smoke stack. The smoke stack refers to the battery stack 2 including the battery cell from which the gas and debris are discharged from the smoke exhaust valve. The debris 100 adhering to the roof-shaped heat insulating material 4 is guided to the end portion 22 along the guide portion 21. Since the end portion 22 is located between adjacent battery stacks 2, when the debris 100 falls from the end portion 22, the debris 100 falls into the space formed between the adjacent battery stacks 2. Thereby, structurally, the battery stacks 2 are not connected by the debris 100, so that a short circuit between adjacent battery stacks 2 can be prevented. Further, the upper cover 12 can be protected by the heat insulating material 4, and cation ignition in the upper cover 12 can be prevented.

[0021] As a comparative example, in a structure in which the heat insulating material spreads horizontally as in the conventional structure, the debris falls so as to connect adjacent battery stacks, and the adjacent battery stacks are connected by the debris and short-circuited. Further, cation ignition occurs due to the temperature rise of the upper cover.

[0022] In contrast, in the battery pack 1, structurally, the debris 100 does not connect between the battery stacks 2. In the battery pack 1, the debris 100 discharged upward from the battery cell can be dropped onto the fume stack, and the debris 100 can be dropped between the battery stacks 2 along the heat insulating material 4. Thereby, it is possible to prevent the structural connection between the battery stacks 2 and prevent a short circuit between the battery stacks 2.

[0023] As described above, according to the embodiment, since the debris 100 is guided by the roof-shaped heat insulating material 4 and falls into the space between the adjacent battery stacks 2 from the end portion 22 which is the lower end of the heat insulating material 4, the debris 100 does not straddle between the adjacent battery stacks 2, and it is possible to prevent a short circuit.

[0024] Further, the shape of the heat insulating material 4 is not limited to a roof shape. As shown in FIG. 3, an arc-shaped heat insulating material 4 may be disposed above the battery stack 2. The guide portion 21 of the heat insulating material 4 is curved so as to approach downward as it approaches one of the both side end portions 22. Alternatively, as shown in FIG. 4, a U-shaped heat insulating material 4 may be disposed above the battery stack 2.

Explanation of Reference Numerals

[0025] 1 Battery pack 2 Battery stack 3 Case 4 Heat insulating material 11 Lower case 12 Upper cover 21 Guide portion 22 End portion 31 First roof member 32 Second roof member

Claims

1. A battery stack consisting of multiple battery cells stacked on top of each other, A case for housing a plurality of the battery stacks arranged in the width direction of the battery cells, An insulating material is placed inside the case above the battery stack to receive the high-temperature gas and debris released from the exhaust valve of the battery cell, A battery pack equipped with, The aforementioned insulating material is A guide portion that covers the entire battery stack in the width direction of the battery cell and extends beyond the battery cell, It forms the lower end of the guide portion and has both ends in the width direction of the battery cell, The guide portion is inclined or curved so as it approaches one of the two ends, and guides the debris attached to the guide portion to the end. At least one of the aforementioned ends is located between adjacent battery stacks in the width direction of the battery cell. A battery pack characterized by the following features.

2. The aforementioned end is located below the upper surface of the battery cell in the vertical direction. The battery pack according to feature 1.

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