battery pack

Abstract

The objective of this invention is to prevent short circuits between adjacent battery stacks caused by debris ejected from battery cells. A battery pack includes: a battery stack having multiple battery cells stacked on top of it; a housing housing the multiple battery stacks; and a heat-insulating material disposed inside the housing above the battery stacks. In the battery pack, the heat-insulating material has: a guide portion covering the entire battery stack in the width direction of the battery cells and extending outwards beyond the battery cells; and two side ends forming the lower ends of the guide portion and located in the width direction of the battery cells. The guide portion is inclined downwards with each of the two side ends, guiding debris attached to the guide portion to the end. At least one of the two side ends is located between adjacent battery stacks in the width direction of the battery cells.

Description

Technical Field

[0001] This invention relates to a battery pack. Background Technology

[0002] Patent document 1 discloses a battery pack comprising a battery module having multiple battery cells stacked on top of it and a housing for housing the battery module, and having a heat-insulating material disposed above the battery module and an insulator disposed above the exhaust port of the battery cell.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2023-046977 Summary of the Invention

[0004] However, in the structure described in Patent Document 1, the heat insulation material extends horizontally, making it impossible to control the landing position of fragments adhering to the heat insulation material after being discharged from the vent of the battery cell. Therefore, if fragments fall in a manner that connects adjacent battery stacks, adjacent battery stacks may short-circuit due to the fragments.

[0005] The present invention was made in view of the above circumstances, and its object is to provide a battery pack capable of preventing short circuits between adjacent battery stacks caused by debris discharged from the battery cells.

[0006] The battery pack of the present invention comprises: a battery stack having a plurality of battery cells stacked thereon; a housing housing the plurality of battery stacks arranged in a width direction of the battery cells; and a heat-insulating material disposed inside the housing above the battery stacks and receiving high-temperature gas and debris discharged from the exhaust valves of the battery cells. In the battery pack, the heat-insulating material has: a guide portion covering the entire battery stack in the width direction of the battery cells and extending to a position further outward than the battery cells; and two end portions forming the lower ends of the guide portions and located in the width direction of the battery cells. The guide portions are inclined or bent downward as they approach one of the two end portions, and guide the debris attached to the guide portion to the end portion. At least one of the two end portions is located between adjacent battery stacks in the width direction of the battery cells.

[0007] Invention Effects

[0008] In this invention, short circuits between adjacent battery stacks caused by debris ejected from the battery cells can be prevented. Attached Figure Description

[0009] Figure 1 This is a schematic diagram illustrating the battery pack in the implementation method.

[0010] Figure 2This diagram illustrates the location where debris ejected from a battery cell falls when it adheres to the insulating material.

[0011] Figure 3 This is a schematic diagram showing a variation of the thermal insulation material.

[0012] Figure 4 This is a schematic diagram illustrating another variation of thermal insulation materials. Detailed Implementation

[0013] The battery pack in the embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below.

[0014] Figure 1 This is a schematic diagram showing the battery pack in the embodiment. The battery pack 1 is installed in electric vehicles such as hybrid vehicles or electric vehicles. The battery pack 1 stores the electricity used for driving the electric vehicle. The battery pack 1 includes a battery stack 2 with multiple battery cells stacked on top of each other, a housing 3 that houses the battery stack 2, and a heat-insulating material 4 disposed inside the housing 3.

[0015] Battery stack 2 is a battery pack consisting of multiple battery cells electrically connected in series. Each battery cell is a square unit with a rectangular frame, and terminals are provided on the upper surface of the frame. The battery cells are composed of lithium-ion batteries. Battery stack 2 has a stack of multiple battery cells stacked along a first direction. The first direction is the same as the X direction and is both the thickness direction of the battery cells and the stacking direction of the stack. Adjacent battery cells in the first direction are electrically connected to each other via busbars. In adjacent battery cells in the first direction, the negative terminal of one battery cell is connected to the positive terminal of another battery cell via a busbar.

[0016] The housing 3 is a battery pack housing that houses multiple battery stacks 2. The housing 3 is made of metal. The interior of the housing 3 houses multiple battery stacks 2 arranged in a second direction. The second direction is orthogonal to the first direction and is the same as the Y direction. The second direction is the width direction of both the battery cells and the battery stacks 2. Adjacent battery stacks 2 are arranged separately in the second direction.

[0017] The housing 3 has a lower housing 11 and an upper cover 12. The lower housing 11 is a housing with an opening at the top, forming a receiving chamber for accommodating the battery stack 2. The upper cover 12 is installed on the lower housing 11 to close the opening of the lower housing 11. The lower housing 11 and the upper cover 12 are fastened together by bolts.

[0018] A cationic electrophoretic coating is applied to the surface of the top cover 12 as a rust-preventive coating. To prevent spontaneous combustion of the cationic coating used as the electrodeposited coating on the top cover 12, direct contact between high-temperature gases and high-temperature debris is undesirable. Since debris is conductive, if it connects adjacent battery stacks 2, the adjacent battery stacks 2 may become electrically connected due to the debris. Therefore, it is undesirable for debris to fall in a manner that connects the battery stacks 2. Thus, the battery pack 1 is configured to prevent high-temperature gases and debris from directly impacting the top cover 12 and to suppress debris from falling in a manner that connects adjacent battery stacks 2.

[0019] The heat insulation material 4 is disposed inside the housing 3 above the battery stack 2 and is a component that receives high-temperature gases and debris discharged from the vent valve located on the upper surface of the battery cell frame. The heat insulation material 4 is a component used to protect the top cover 12 from gases and debris discharged from the battery cell. The battery cell is a lithium-ion battery, and in the event of thermal runaway of the lithium-ion battery, high-temperature gases and conductive debris are discharged from the vent valve of the battery cell.

[0020] The thermal insulation material 4 is formed into a roof-type structure that completely covers the battery stack 2. The thermal insulation material 4 is installed on the top cover 12. The thermal insulation material 4 is disposed above each battery stack 2. The thermal insulation material 4 has a guide portion 21 and an end portion 22.

[0021] The guide section 21 is inclined relative to the horizontal direction, guiding the debris attached to the guide section 21 to the end 22. The guide section 21 covers the entire battery stack 2 in the second direction and extends to a position further outward than the battery cell in the second direction. The guide section 21 is inclined downward as it approaches one of the ends 22 on both sides.

[0022] End 22 is the end on both sides in the second direction and forms the lower end of the guide 21. At least one of the two end 22 is located between adjacent battery stacks 2 in the second direction. End 22 is located below the upper surface of the battery cell in the vertical direction.

[0023] For example, the roof-type insulation material 4 includes a flat first roof component 31 and a flat second roof component 32. The first roof component 31 and the second roof component 32 are joined and integrated. The first roof component 31 slopes downwards from the center side of the battery stack 2 in the Y direction. The second roof component 32 slopes downwards from the center side of the battery stack 2 in the Y direction. The second roof component 32 slopes to the opposite side of the first roof component 31 relative to the Y direction.

[0024] like Figure 2As shown, if a battery cell experiences thermal runaway, the gas generated inside the battery cell is discharged through the vent valve, and the gas and debris impact the roof-type insulation material 4. The debris hitting the insulation material 4 falls from the insulation material 4 onto the upper surface of the smoking battery stack. The smoking battery stack refers to the battery stack 2 that includes the battery cells from which the gas and debris have been discharged through the vent valve. The debris 100 attached to the roof-type insulation material 4 is guided along the guide portion 21 to the end portion 22. The end portion 22 is located between adjacent battery stacks 2, so the debris 100 falls from the end portion 22, thus the debris 100 falls into the space formed between adjacent battery stacks 2. Therefore, structurally, the battery stacks 2 will not connect with each other due to the debris 100, thus preventing short circuits between adjacent battery stacks 2. Furthermore, the top cover 12 can be protected by the insulation material 4, and the cations in the top cover 12 can be prevented from igniting.

[0025] As a comparative example, in a structure where the insulation material extends horizontally as in conventional structures, fragments fall in a manner that connects adjacent battery stacks, causing them to short-circuit. Furthermore, the cations ignite due to the temperature rise of the top cover.

[0026] In contrast, in battery pack 1, structurally, the fragments 100 are not connected to each other in the battery stacks 2. In battery pack 1, the fragments 100 discharged from the battery cells upwards can fall above the smoking battery stacks, and the fragments 100 can fall along the heat insulation material 4 between the battery stacks 2. Thus, structurally, the battery stacks 2 can be prevented from connecting to each other, and short circuits between the battery stacks 2 can be prevented.

[0027] As explained above, according to the embodiment, the fragment 100 is guided by the roof-type thermal insulation material 4 and falls from the lower end 22 of the thermal insulation material 4 into the space between adjacent battery stacks 2, so that the fragment 100 will not cross between adjacent battery stacks 2, thus preventing short circuits.

[0028] Furthermore, the shape of the insulation material 4 is not limited to a roof type. For example... Figure 3 As shown, an arc-shaped heat-insulating material 4 can be positioned above the battery stack 2. The guide portion 21 of the heat-insulating material 4 is bent downwards along one of the ends 22 on both sides. Alternatively, as... Figure 4 As shown, a U-shaped heat insulation material 4 can also be placed on top of the battery stack 2.

[0029] Symbol Explanation

[0030] 1-Battery pack, 2-Battery stack, 3-Housing, 4-Insulation material, 11-Lower housing, 12-Upper cover, 21-Guide section, 22-End section, 31-First roof component, 32-Second roof component.

Claims

1. A battery pack comprising: A battery stack, which consists of multiple battery cells stacked together; A housing that accommodates a plurality of battery stacks arranged in the width direction of the battery cells; and A thermal insulation material, disposed inside the housing above the battery pack, and receiving high-temperature gases and debris discharged from the vent valves of the battery cells, is characterized in that... The thermal insulation material has the following characteristics: A guide portion that covers the entire battery stack in the width direction of the battery cell and extends to the outermost part of the battery cell; and The ends on both sides form the lower ends of the guide portion and are located in the width direction of the battery cell. The guide portion is tilted or bent downwards as it approaches one of the ends on either side, and guides the fragment attached to the guide portion to that end. At least one of the ends on both sides is located between adjacent battery stacks in the width direction of the battery cell.

2. The battery pack according to claim 1, characterized in that, The end is located below the upper surface of the battery cell in the vertical direction.

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