Battery pack

Abstract

A battery pack is provided with: a battery cell having a relief valve that opens as a result of an increase in internal pressure and discharges gas to the outside; an exhaust passage through which the gas discharged from the relief valve flows; a heat insulation member provided so as to cover the relief valve; and a holding member that holds the heat insulating member, in which a housing portion is provided in a wall portion of the exhaust passage at a position facing the heat insulating member, and the heat insulating member insulates heat between the exhaust passage and the battery cells when the safety valve is not opened. When the safety valve is opened, gas discharged from the safety valve is separated from the holding member and stored in the storage part, and the gas discharged from the safety valve is insulated from the wall part of the exhaust passage.

Description

Technical Field

[0001] This invention relates to battery packs. Background Technology

[0002] International Publication No. 2020 / 110448 discloses the following: In a battery pack with an exhaust pipe provided above the battery module, an impact absorption layer is provided on the surface of the exhaust pipe facing the safety valve of the battery cell to protect the exhaust pipe from the high-temperature gas released from the safety valve. Summary of the Invention

[0003] In the structure described in International Patent Publication No. 2020 / 110448, since no heat-insulating member is provided to separate the battery cells from the gas in the exhaust pipe, normal cells will be heated by the gas in the exhaust pipe when gas is released from an abnormal battery cell. In this case, the normal cells become high-temperature and begin to generate abnormal heat, and the abnormal heating of the battery cells may be cascading. Therefore, it is advisable to provide a heat-insulating member to separate the battery cells from the gas in the exhaust pipe.

[0004] However, if a heat insulation component is added to the structure that provides a heat insulation component to protect the exhaust pipe, as described in International Publication No. 2020 / 110448, to insulate the battery cell from the gas in the exhaust pipe, the cost will increase.

[0005] The present invention was made in view of the above circumstances, and its object is to provide a battery pack that can suppress the increase in cost while protecting the walls of the exhaust passage and the battery cells from the effects of high-temperature gases emitted from the battery cells.

[0006] The battery pack of the present invention is characterized by comprising: a battery cell having a safety valve that opens due to an increase in internal pressure and releases gas to the outside; a battery module having a plurality of said battery cells arranged in an array; a housing for housing said battery modules; an exhaust passage for gas to flow from said safety valve; a heat insulation member disposed such that it covers said safety valve and faces said exhaust passage; and a retaining member disposed between said battery cell and said housing, retaining said heat insulation member, wherein a receiving portion is provided on the wall of said exhaust passage at a position opposite to said heat insulation member, said heat insulation member heats the exhaust passage and said battery cell when said safety valve is closed, and when said safety valve is open, said heat insulation member separates from said retaining member and is received in said receiving portion by gas released from said safety valve, thereby heats the gas released from said safety valve and the wall of said exhaust passage.

[0007] In this invention, it is possible to suppress the increase in cost while protecting the walls of the exhaust passage and the battery cells from the effects of high-temperature gases emitted from the battery cells. Attached Figure Description

[0008] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which the same reference numerals denote the same parts, and wherein:

[0009] Figure 1 This is a schematic diagram illustrating a battery pack implementation method;

[0010] Figure 2 This is a diagram showing a heat-insulating component that separates the battery cell from the exhaust passage;

[0011] Figure 3 This diagram illustrates the state in which, when the safety valve is open, the heat-insulating member, which is separated from the retaining member, is housed in the receiving part, thus insulating the wall of the exhaust passage from the gas.

[0012] Figure 4 This is a diagram showing the structure of the storage section;

[0013] Figure 5 This is a schematic diagram illustrating a modified battery pack;

[0014] Figure 6 This is a diagram showing the safety valve opening in a modified battery pack. Detailed Implementation

[0015] The battery pack according to embodiments of the present invention will now be described in detail. However, the present invention is not limited to the embodiments described below.

[0016] Figure 1 This diagram schematically illustrates a battery pack embodiment. The battery pack 1 is an energy storage device that houses a battery module 3, consisting of multiple stacked battery cells 2, inside a housing 4. The battery pack 1 is installed in electric vehicles such as electric cars or hybrid electric vehicles. In electric vehicles, the vehicle travels by supplying the electricity stored in the battery pack 1 to a motor for driving.

[0017] The battery pack 1 includes a battery module 3, a housing 4, a common plate 5, a heat insulation component 6, a retaining component 7, and an exhaust passage 8.

[0018] Battery module 3 is a battery pack composed of multiple battery cells 2 arranged in a row. Battery module 3 has a stack of battery cells 2 and coolers 9 stacked alternately. Cooler 9 has a flow path inside for coolant to flow through, thereby cooling the battery cells 2. Cooler 9 is formed into a hollow flat plate shape.

[0019] Battery cell 2 is a rectangular battery formed in the shape of a cuboid. Battery cell 2 is composed of lithium-ion batteries. Battery cell 2 has a square cell casing and a safety valve 10. The safety valve 10 is provided on the lower surface of the cell casing of battery cell 2.

[0020] Safety valve 10 opens due to an increase in internal pressure within battery cell 2, releasing gas from inside battery cell 2 to the outside. Safety valve 10 opens when the internal pressure of battery cell 2 rises above a predetermined value. For example, safety valve 10 includes a thin-walled portion that is thinner than other parts and a groove provided in the thin-walled portion. When the internal pressure of battery cell 2 rises, the thin-walled portion splits at the groove, thereby opening safety valve 10. Gas inside battery cell 2 is discharged from safety valve 10 to exhaust passage 8.

[0021] The exhaust passage 8 is a passage for gas to flow from the safety valve 10. The exhaust passage 8 is located below the battery module 3 and is divided by the housing 4, the common plate 5, and the heat insulation component 6. The safety valve 10 of each battery cell 2 is connected to the exhaust passage 8. Gas can be released from any of the multiple battery cells 2 into the exhaust passage 8.

[0022] The housing 4 houses the battery module 3. The housing 4 includes an upper cover and a lower shell. The housing 4 is a battery pack housing that houses multiple battery cells 2. The battery cells 2 are located at the bottom of the housing 4. At the bottom of the housing 4, at a position corresponding to the safety valve 10 of each battery cell 2, a vent 11 extending through in the height direction is provided. The vent 11 is a through hole through which the gas released from the safety valve 10 is discharged into the vent passage 8.

[0023] The common plate 5 is a plate-shaped protective member disposed below the housing 4 and protecting the battery pack 1 against external forces input from below. The common plate 5 is formed to face the entire lower surface of the housing 4 and is mounted on a support member supporting the housing 4 or on the housing 4 itself. The common plate 5 is a metal plate forming the lowest surface. The common plate 5 is made of aluminum.

[0024] The heat insulation member 6 is a flat plate-shaped heat insulation member disposed opposite to the safety valve 10 and arranged to cover the safety valve 10. The heat insulation member 6 is located below the safety valve 10, that is, below the battery cell 2. The heat insulation member 6 is insulating. The heat insulation member 6 is made of mica, alumina, glass, calcium silicate, etc. The heat insulation member 6 is held by the retaining member 7. The heat insulation member 6 and the retaining member 7 are integrated.

[0025] The retaining member 7 is a flat plate-shaped component disposed between the battery cell 2 and the housing 4. The retaining member 7 is insulating. The retaining member 7 is made of resin. For example, the retaining member 7 is a resin film or a resin sheet. The battery cell 2 is disposed at the bottom of the housing 4 via the retaining member 7.

[0026] In the battery pack 1 configured in this way, the heat insulation member 6 is configured to protect the wall of the exhaust passage 8 from the gas released from the safety valve 10, and to protect the battery cell 2 from the high-temperature gas in the exhaust passage 8. The heat insulation member 6 is a heat insulation member used to insulate the gas released from the safety valve 10 from the wall of the exhaust passage 8, and also a heat insulation member used to insulate the gas in the exhaust passage 8 from the battery cell 2.

[0027] The heat insulation member 6 is configured to be detachable from the retaining member 7. A through hole corresponding to the shape of the heat insulation member 6 is provided on the retaining member 7. The heat insulation member 6 is inserted into the through hole provided in the retaining member 7. For example, the state in which the heat insulation member 6 is inserted into the through hole of the retaining member 7 is the state in which the heat insulation member 6 is held by the retaining member 7. The retaining member 7 holds the heat insulation member 6 with a strength sufficient to allow the heat insulation member 6 to detach from the retaining member 7 when the battery cell 2 abnormally heats up and releases gas or particles from the safety valve 10, and this gas comes into contact with the heat insulation member 6. Furthermore, the heat insulation member 6 has the strength to not be damaged by the gas or particles released from the safety valve 10. The heat insulation member 6 has the strength to maintain the same shape as before separation from the retaining member 7.

[0028] The heat insulation member 6 faces the exhaust passage 8 through the vent 11 of the housing 4. A receiving portion 12 is provided in the exhaust passage 8, facing the heat insulation member 6. The receiving portion 12 is configured to receive the heat insulation member 6 after it has separated from the holding member 7. A space for receiving the heat insulation member 6 is provided in the exhaust passage 8. The receiving portion 12 is provided on the common plate 5 and has a protrusion 13 protruding towards the battery cell 2. The protrusion 13 is formed in a shape corresponding to the shape of the heat insulation member 6. For example, the protrusion 13 is formed to completely surround the separated heat insulation member 6. The protrusion 13 is provided when the common plate 5 is stamped.

[0029] When the battery cell 2 is functioning normally and the safety valve 10 is not open, the heat insulation member 6 insulates the battery cell 2 from the exhaust passage 8. Even if other battery cells 2 generate abnormal heat and high-temperature gas or particles pass through the lower surface of the casing 4, the heat insulation member 6, which is present in the normal battery cell 2, also functions as a heat insulation component, preventing the normal battery cell 2 from heating up due to the gas in the exhaust passage 8.

[0030] When the safety valve 10 opens in the abnormally overheating battery cell 2, the heat insulation member 6 separates from the holding member 7 and moves toward the receiving section 12 by the gas released from the safety valve 10. While stored in the receiving section 12, it insulates the common plate 5 from the gas. The separated heat insulation member 6 is held in the receiving section 12 by gravity. When the battery cell 2 abnormally overheats, the heat insulation member 6 falls onto the common plate 5, protecting the common plate 5 from the high-temperature gas.

[0031] like Figure 3 As shown, the heat insulation member 6 housed in the housing section 12 is positioned between the gas released from the open safety valve 10 toward the housing section 12 and the wall of the exhaust passage 8, catching the gas. While catching the gas, the heat insulation member 6 insulates the gas from the wall of the exhaust passage 8. When the safety valve 10 is open in any one of the battery cells 2, the other battery cells 2 are insulated from the gas flowing in the exhaust passage 8 by the heat insulation member 6 held in the holding member 7.

[0032] As explained above, according to the embodiment, the normal battery cell 2 is thermally insulated from the high-temperature gas in the exhaust passage 8 by the heat insulation member 6 held in the holding member 7. In the event of abnormal heating of the battery cell 2, the wall of the exhaust passage 8 can be protected by moving the heat insulation member 6 to the storage part 12. The wall of the exhaust passage 8 and the battery cell 2 can be protected by a single heat insulation member 6. As a result, the increase in cost can be suppressed.

[0033] Furthermore, the heat insulation component 6 can also be held by a material that melts due to the heat generated by the abnormal heating of the battery cell 2. For example, the heat insulation component 6 and the retaining component 7 are fused together, and the retaining component 7 melts due to the high-temperature gas released from the safety valve 10. By causing the retaining component 7 to melt due to the gas from the safety valve 10, the heat insulation component 6 is separated from the retaining component 7.

[0034] Alternatively, a resin spacer can be used instead of the cooler 9. The spacer is insulating. In the battery module 3, spacers are arranged between adjacent battery cells 2 in the stacking direction.

[0035] Furthermore, the storage section 12 can be any shape capable of accommodating the heat insulation component 6; its shape is not particularly limited. For example... Figure 4 As shown, the storage section 12 can also be formed by multiple protrusions 13.

[0036] Furthermore, the exhaust passage 8 is not limited to a structure defined by the housing 4, the common plate 5, and the heat insulation member 6. Also, the member facing the heat insulation member 6 is not limited to the common plate 5. Moreover, the exhaust passage 8 is not limited to a structure located below the battery module 3, but can also be located above the battery module 3. As a variation, the battery pack 1 can have a structure in which the exhaust passage 8 is provided above the battery module 3.

[0037] like Figure 5As shown, in the modified battery pack 1, a safety valve 10 is provided on the upper surface of the battery cell 2's housing, and an exhaust passage 8 is provided above the battery module 3. A heat insulation member 6 is positioned above the safety valve 10, i.e., above the battery cell 2. A retaining member 7 is positioned above the battery cell 2. The exhaust passage 8 is divided by an exhaust pipe 14, the heat insulation member 6, and the retaining member 7. The exhaust pipe 14 is a member forming the wall portion of the exhaust passage 8. The exhaust pipe 14 is housed inside the housing 4.

[0038] A receiving portion 15 is provided on the wall of the exhaust duct 14, facing the heat insulation member 6. The receiving portion 15 is designed to receive the heat insulation member 6, which has separated upwards from the retaining member 7. Figure 6 As shown, the separated heat insulation component 6 is held in the storage section 15 by overcoming gravity under the action of gas or particles released from the safety valve 10 of the battery cell 2.

[0039] The housing 15 has a protrusion 16 extending from the exhaust pipe 14 toward the battery cell 2. A heat-insulating member 6 housed in the housing 15 is positioned between the gas released from the safety valve 10 toward the housing 15 and the wall of the exhaust pipe 14, catching the gas. While catching the gas, the heat-insulating member 6 insulates the gas from the wall of the exhaust pipe 14. When the gas release from the safety valve 10 ends, the heat-insulating member 6, held in the housing 15, can fall to the safety valve 10 side under gravity. Alternatively, the exhaust pipe 14 can be a component different from the housing 4, or it can be the top cover of the housing 4.

Claims

1. A battery pack, characterized in that, The battery pack includes: The battery cell has a safety valve that opens and releases gas to the outside when the internal pressure rises. A battery module having multiple battery cells arranged in a configuration; A housing that houses the battery module; An exhaust passage for the flow of gas released from the safety valve; A thermal insulation component, which is arranged to cover the safety valve and faces the exhaust passage; as well as A retaining member, disposed between the battery cell and the housing, retains the heat insulation member. A receiving portion is provided on the wall of the exhaust passage, facing the heat insulation member. The heat insulation component isolates the exhaust passage from the battery cell when the safety valve is closed, and separates from the retaining component and is housed in the housing portion by the gas released from the safety valve when the safety valve is open, thus insulating the gas released from the safety valve from the wall of the exhaust passage.

2. The battery pack according to claim 1, characterized in that, The heat insulation member housed in the housing receives the gas released from the safety valve that is opened toward the housing while being located between the wall of the exhaust passage and the gas.

3. The battery pack according to claim 2, characterized in that, When the safety valve is open in any one of the plurality of battery cells, the other battery cells are insulated from the gas in the exhaust passage by the heat-insulating member held in the retaining member.

4. The battery pack according to claim 3, characterized in that, The battery pack includes a common plate disposed below the housing. The exhaust passage is divided by the housing and the common plate. An exhaust port opening into the exhaust passage is provided at the bottom of the housing. The safety valve is located on the lower surface of the battery cell. The retaining member is disposed between the lower surface of the battery cell and the bottom of the housing. The heat insulation component faces the exhaust passage through the exhaust hole. The storage section is disposed on the common plate and includes multiple protrusions protruding toward the battery cell side.

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