Battery pack

Abstract

To provide a battery pack capable of preventing leakage of gas and damage of a cover by a simple configuration.SOLUTION: A battery pack includes: a plurality of battery cells 11; a case body 31 having an opening 30; a cover 21 that is attached to the case body 31 so as to close the opening 30 and that forms, together with the case body 31, a space 20 for accommodating the plurality of battery cells 11; and a plate member 41 that comprises metal or ceramic and that has a first portion 42 disposed between each of the plurality of battery cells 11 and the cover 21 in the space 20 and a second portion 46 provided at a peripheral edge of the first portion 42 and sandwiched by the case body 31 and the cover 21.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] For example, International Publication No. 2020 / 189590 (Patent Document 1) discloses a battery pack including a secondary battery, a housing for accommodating the secondary battery, and a plate-shaped reinforcing portion extending from one end to the other end in the longitudinal direction of the housing and arranged in the height direction of the secondary battery to reinforce the housing.

[0003] In addition, JP2021-535556A (Patent Document 2) discloses a battery pack comprising a single cell, a first panel and a second panel connected to the upper and lower surfaces of the single cell, respectively, and a thermally conductive plate provided between the single cell and the first panel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 189590 [Patent Document 2] Special Publication No. 2021-535556 Summary of the Invention [Problem to be solved by the invention]

[0005] In the battery pack disclosed in the above-mentioned Patent Document 1, the housing (case) that houses the secondary battery is composed of a rectangular box-shaped main body with an open top and a cover that covers the opening of the main body. In such a battery pack, if flammable high-pressure gas is generated from the battery cell during a battery abnormality, or if spontaneous combustion occurs due to the generation of high-pressure gas, there is a concern that the gas may leak from between the main body and the cover, or that the cover may be damaged by the gas or shock waves associated with spontaneous combustion.

[0006] SUMMARY OF THE PRESENT DISCLOSURE OF THE PRESENT DISCLOSURE An object of the present invention is to solve the above problems and to provide a battery pack that is capable of preventing gas leakage and damage to the cover with a simple structure. [Means for solving the problem]

[0007] [1] A battery pack comprising: a plurality of battery cells; a case body having an opening; a cover attached to the case body so as to close the opening and which, together with the case body, forms a space to accommodate the plurality of battery cells; a first portion disposed between the plurality of battery cells and the cover in the space; and a second portion provided on the periphery of the first portion and sandwiched between the case body and the cover, and a plate member made of metal or ceramic.

[0008] In the battery pack configured in this manner, the first portion of the plate member receives gas generated from the battery cells or shock waves caused by spontaneous combustion, thereby preventing damage to the cover, and the second portion of the plate member seals the gap between the case body and the cover, thereby preventing exposure of the gas. In this configuration, the first and second portions are integrally provided on the plate member, so that the simple configuration can prevent damage to the cover and leakage of gas.

[0009] [2] The battery pack described in [1], wherein the battery cell has an exterior body including a top surface and a side surface, and contains an electrode body and an electrolyte, and a gas outflow valve that allows gas to flow from inside the exterior body through the top surface to the space when pressure inside the exterior body reaches or exceeds a predetermined value, and the first portion faces the top surface and is disposed opposite the side surface, forms a gas flow passage communicating with the space, and further includes a duct that exhausts the gas from the space.

[0010] In the battery pack configured in this manner, gas that has flowed out from inside the exterior body into the space through the top surface can be more reliably received by the first portion disposed between the top surface and the cover. Furthermore, by discharging the gas through the duct, it is possible to suppress an increase in internal pressure in the space housing the multiple battery cells. Effect of the Invention

[0011] As described above, according to the present invention, it is possible to provide a battery pack that is capable of preventing gas leakage and damage to the cover with a simple structure. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a battery pack according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded view showing the battery pack in FIG. [Diagram 3] FIG. 2 is a perspective view showing a battery cell. [Figure 4] 4 is a cross-sectional view showing a schematic diagram of the battery pack as viewed in the direction of the arrows on line IV-IV in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings, in which the same or corresponding components are designated by the same reference numerals.

[0014] Fig. 1 is a perspective view showing a battery pack in an embodiment of the present invention. Fig. 2 is an exploded view showing the battery pack in Fig. 1. Fig. 3 is a perspective view showing a battery cell. Fig. 4 is a cross-sectional view showing a schematic view of the battery pack as seen in the direction of the arrows on line IV-IV in Fig. 1.

[0015] 1 to 4, a battery pack 100 is used as a power source for driving a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV).

[0016] In this specification, for convenience of explaining the structure of the battery pack 100, the axis extending in the stacking direction of the multiple battery cells 11 described later and in the horizontal direction is referred to as the "Y axis," the axis extending in the horizontal direction and perpendicular to the Y axis is referred to as the "X axis," and the axis extending in the vertical direction is referred to as the "Z axis." As shown in Fig. 4, the battery pack 100 basically has a structure that is symmetrical with respect to a virtual plane 110 parallel to the Y-axis-Z-axis plane.

[0017] The battery pack 100 has a plurality of battery cells 11. The plurality of battery cells 11 are stacked in the Y-axis direction. The battery cells 11 are made of lithium ion batteries. The battery cells 11 are square and have a rectangular thin plate shape. The plurality of battery cells 11 are stacked such that the Y-axis direction is the thickness direction of the battery cells 11.

[0018] The battery cell 11 has an exterior body 12. The exterior body 12 is made of a rectangular parallelepiped housing, and forms the external appearance of the battery cell 11. The exterior body 12 contains an electrode assembly and an electrolyte.

[0019] Exterior body 12 has a pair of first side surfaces 14 (14j, 14k), a pair of second side surfaces 13 (13j, 13k), a top surface 15, and a bottom surface 16.

[0020] The first side surface 14 is a plane perpendicular to the X-axis. The first side surface 14 is parallel to the Y-axis direction, which is the stacking direction of the battery cells 11. The first side surface 14j and the first side surface 14k face opposite each other in the X-axis direction. The second side surface 13 is a plane perpendicular to the Y-axis. The second side surface 13 has the largest area among the multiple side surfaces of the exterior body 12. The second side surface 13j and the second side surface 13k face opposite each other in the Y-axis direction. The top surface 15 and the bottom surface 16 each are a plane perpendicular to the Z-axis. The top surface 15 faces upward. The bottom surface 16 faces downward.

[0021] Battery cell 11 further has a gas outflow valve 17. Gas outflow valve 17 is provided on top surface 15. Gas outflow valve 17 is provided at the center position of top surface 15 in the X-axis direction. When the pressure inside exterior body 12 reaches or exceeds a predetermined value, gas outflow valve 17 allows gas to flow from inside exterior body 12 through top surface 15 to the outside of exterior body 12 (space 20 described below).

[0022] The battery cell 11 further has electrode terminals 18, each of which is a pair of a positive terminal 18P and a negative terminal 18N. The electrode terminals 18 are provided on the top surface 15. The positive terminal 18P and the negative terminal 18N are provided apart from each other in the X-axis direction. The positive terminal 18P and the negative terminal 18N are provided on either side of the gas outflow valve 17 in the X-axis direction.

[0023] The multiple battery cells 11 are stacked such that the second side faces 13j face each other and the second side faces 13k face each other between the battery cells 11, 11 adjacent to each other in the Y-axis direction. As a result, the positive electrode terminals 18P and the negative electrode terminals 18N are arranged alternately in the Y-axis direction in which the multiple battery cells 11 are stacked. Between the battery cells 11, 11 adjacent to each other in the Y-axis direction, the positive electrode terminals 18P and the negative electrode terminals 18N arranged in the Y-axis direction are connected to each other by a bus bar (not shown). The multiple battery cells 11 are electrically connected to each other in series.

[0024] The battery cell in the present invention is not limited to a rectangular shape, and may be a cylindrical shape. For example, the multiple battery cells are arranged at intervals from each other in the X-Y plane in an upright position with the cylindrical axis of each battery cell extending in the Z-axis direction. In this case, the gas outflow valve may be provided inside the sealing body that constitutes the top surface of the battery cell.

[0025] 2, a cell stack 120 is formed by multiple battery cells 11 stacked in the Y-axis direction. The cell stack 120 has a rectangular parallelepiped shape. The length of the cell stack 120 in the Y-axis direction is greater than the length of the cell stack 120 in the Z-axis direction and is greater than the length of the cell stack 120 in the X-axis direction. When viewed in a plan view in the Z-axis direction, the cell stack 120 has a rectangular shape in which the Y-axis direction is the longitudinal direction and the X-axis direction perpendicular to the Y-axis direction is the lateral direction.

[0026] The battery pack 100 further has a pair of end plates 91 and a pair of bind bars 66 (not shown in FIG. 2, see FIG. 4). The pair of end plates 91 are respectively arranged at both ends of the cell stack 120 (plurality of battery cells 11) in the Y-axis direction. The pair of bind bars 66 are respectively arranged at both ends of the cell stack 120 in the X-axis direction. The bind bars 66 extend in the Y-axis direction and are connected at both ends to the pair of end plates 91. The multiple battery cells 11 are held together by the pair of end plates 91 and the pair of bind bars 66.

[0027] The battery pack 100 further includes a case body 31 and a cover 21. The case body 31 and the cover 21 are made of metal. The case body 31 and the cover 21 are formed of aluminum, for example. The case body 31 has an opening 30. The opening 30 faces upward. The cover 21 is attached to the case body 31 so as to close the opening 30. The cover 21, together with the case body 31, forms a space 20 that houses a plurality of battery cells 11.

[0028] The case body 31 has a bottom 51, a pair of first side portions 32, and a pair of second side portions 36. The bottom 51 has a wall shape arranged along the X-axis-Y-axis plane with the thickness direction being in the Z-axis direction. The bottom 51 has a rectangular shape in a plan view seen in the Z-axis direction. The cell stack 120 is placed on the bottom 51. A cooling plate 61 is interposed between the bottom 51 and the cell stack 120. The cooling plate 61 is provided with a refrigerant passage 62 extending in the Y-axis direction.

[0029] The pair of first side portions 32 and the pair of second side portions 36 rise from the periphery of the bottom portion 51. The pair of first side portions 32 face each other in the X-axis direction, sandwiching the space 20 therebetween. The first side portions 32 have a wall shape disposed along the Y-axis-axis plane, with the X-axis direction being the thickness direction. The pair of second side portions 36 face each other in the Y-axis direction, sandwiching the space 20 therebetween. The second side portions 36 have a wall shape disposed along the X-axis-axis plane, with the Y-axis direction being the thickness direction.

[0030] The bottom portion 51 is fastened to the pair of first side portions 32 and the pair of second side portions 36 by using a plurality of bolts 52. This configuration is not limited thereto, and the bottom portion 51, the pair of first side portions 32, and the pair of second side portions 36 may be integrally formed from metal.

[0031] The space 20 is formed on the bottom 51 at a position surrounded by the pair of first side portions 32 and the pair of second side portions 36. The opening 30 is defined by upper ends of the pair of first side portions 32 and the pair of second side portions 36. The space 20 is open to the space outside the case body 31 through the opening 30.

[0032] The case body 31 further has a first flange 33. The first flange 33 spreads in a flange-like shape in the surface direction of the X-axis-Y-axis plane from the upper ends of the pair of first side portions 32 and the pair of second side portions 36. The first flange 33 is provided in a frame-like shape along the upper ends of the pair of first side portions 32 and the pair of second side portions 36.

[0033] The cover 21 has a cover body 22 and a second flange 24. The cover body 22 constitutes a main part of the cover 21 and closes the opening 30. The cover body 22 has a saucer shape with the Z-axis direction being the depth direction and opening downward. The second flange 24 spreads in a flange-like shape from the lower end of the cover body 22 in the surface direction of the X-axis-Y-axis plane. The second flange 24 is provided in a frame-like shape along the lower end of the cover body 22. The second flange 24 overlaps with the first flange 33 in the Z-axis direction. The first flange 33 and the second flange 24 are fastened to each other using a plurality of bolts 26, whereby the cover 21 is attached to the case body 31.

[0034] The battery pack 100 further includes a plate member 41. The plate member 41 is made of a material having sufficient heat resistance to not deform even when exposed to high-temperature gas or flame generated from the battery cells 11, and is preferably made of metal or ceramic. The plate member 41 is made of, for example, a metal such as carbon steel, stainless steel, copper, aluminum, or titanium, or a ceramic such as alumina, zirconia, or silica. The surface of the plate member 41 may be coated with a resin material. The thickness of the plate member 41 is smaller than the thickness of the cover 21.

[0035] The plate member 41 has a first portion 42 and a second portion 46. The first portion 42 and the second portion 46 are integrally formed from metal or ceramic. The first portion 42 and the second portion 46 are continuous. The first portion 42 and the second portion 46 are made of the same material. The first portion 42 and the second portion 46 have the same thickness.

[0036] The first portion 42 is provided in the space 20. The first portion 42 is disposed in the space 20 between the multiple battery cells 11 and the cover 21. The first portion 42 is disposed in the space 20 between the cell stack 120 and the cover main body portion 22. The first portion 42 faces the top surface 15 of the battery cell 11 in the Z-axis direction. The first portion 42 faces the gas outflow valve 17 in the Z-axis direction. The first portion 42 faces the electrode terminals 18 (positive electrode terminal 18P, negative electrode terminal 18N) in the Z-axis direction.

[0037] The first portion 42 has a saucer shape that opens downward and whose depth direction is the Z-axis direction. In a plan view in the Z-axis direction, the first portion 42 has a rectangular shape with its longitudinal direction being the Y-axis direction and its short side direction being the X-axis direction perpendicular to the Y-axis direction. The range of the cell stack 120 in the plan view in the Z-axis direction is included in the range of the first portion 42 in the plan view in the Z-axis direction.

[0038] The second portion 46 is provided on the periphery of the first portion 42. The second portion 46 is provided along the periphery of the first portion 42 in a plan view in the Z-axis direction. The second portion 46 spreads out in a brim-like shape from the lower end of the first portion 42 in the surface direction of the X-axis-Y-axis plane. The second portion 46 is provided in a frame-like shape along the lower end of the first portion 42.

[0039] The second portion 46 is sandwiched between the case body 31 and the cover 21. The second portion 46 is interposed between the first flange 33 and the second flange 24. The second portion 46 receives a fastening force from the multiple bolts 26 between the first flange 33 and the second flange 24.

[0040] Space 20 is divided into space 20A and space 20B by plate member 41. Space 20B is surrounded by plate member 41 and cover 21. Space 20A is surrounded by plate member 41 and case body 31. Multiple battery cells 11 are housed in space 20A.

[0041] The battery pack 100 further has a duct 70. The duct 70 is provided opposite the first side surface 14 of the battery cell 11. The duct 70 forms a gas flow passage 72. The gas flow passage 72 communicates with the space 20. The duct 70 exhausts the gas that has flowed out from the gas outflow valve 17 from the space 20.

[0042] The case body 31 further has a rib portion 34. The rib portion 34 protrudes from the first side portion 32 in the X-axis direction and extends in a rib-like manner along the periphery of the first side portion 32. The duct 70 has a pair of duct covers 71. The pair of duct covers 71 are attached to the pair of first side portions 32, respectively. The duct covers 71 are attached to the first side portions 32 so as to abut against the rib portion 34 in the X-axis direction.

[0043] Duct cover 71, together with first side portion 32, forms gas flow passage 72. Gas flow hole 35 is provided in first side portion 32. Gas flow hole 35 is a hole penetrating first side portion 32, and connects space 20 (20A) and gas flow passage 72. Gas flow passage 72 extends in the Y-axis direction and is open at one end thereof.

[0044] It is assumed that flammable gas may be generated inside the exterior body 12 when a battery abnormality such as an internal short circuit occurs in the battery cell 11. The gas is discharged to the space 20 (20A) through the top surface 15 on which the gas outlet valve 17 is provided (gas flow indicated by arrow A in FIG. 4). The gas collides with the plate member 41 and is guided by the first portion 42, so that the gas flows from the center of the space 20 (20A) in the X-axis direction toward both ends, and further flows downward through the gap between the cell stack 120 and the first side portion 32 (gas flow indicated by arrows B and C in FIG. 4). The gas is discharged from the space 20 (20A) through the gas circulation hole 35 to the gas flow passage 72 (gas flow indicated by arrow D in FIG. 4). The gas flows through the gas flow passage 72 in the Y-axis direction and is discharged to the outside of the duct 70 (gas flow indicated by arrow E in FIG. 1).

[0045] As batteries have become higher capacity in recent years, the amount of gas generated in the battery cells 11 has increased. This can cause high-pressure gas to be ejected from the battery cells 11, or the gas can become hot due to increased gas pressure, resulting in spontaneous combustion. To prepare for such cases, the battery pack 100 of this embodiment is provided with a plate member 41 having a first portion 42 and a second portion 46.

[0046] In the space 20, the first portion 42 disposed between the multiple battery cells 11 (cell stack 120) and the cover 21 can receive high-pressure gas ejected from the battery cells 11 or shock waves caused by spontaneous combustion, thereby preventing damage to the cover 21. In addition, the first portion 42 also has a heat insulating function that prevents the cover 21 from being exposed to high-temperature gas. Also, the second portion 46 sandwiched between the case body 31 and the cover 21 can prevent gas from leaking from places other than the exhaust gas path. In this configuration, the first portion 42 and the second portion 46 are provided integrally with the plate member 41, so that the configuration of the battery pack 100 can be simplified.

[0047] Furthermore, in this embodiment, the first part 42 is positioned between the top surface 15 on which the gas outflow valve 17 is provided and the cover 21, so that the high-pressure gas flowing out from the gas outflow valve 17 can be more reliably received by the first part 42.

[0048] To summarize the structure of battery pack 100 in the embodiment of the present invention described above, battery pack 100 in the present embodiment comprises a plurality of battery cells 11, a case body 31 having an opening 30, a cover 21 attached to the case body 31 so as to close the opening 30 and which, together with the case body 31, forms a space 20 for accommodating the plurality of battery cells 11, a first portion 42 positioned between the plurality of battery cells 11 and the cover 21 in the space 20, and a second portion 46 provided on the periphery of the first portion 42 and sandwiched between the case body 31 and the cover 21, and a plate member 41 made of metal or ceramic.

[0049] According to battery pack 100 thus configured in the embodiment of the present invention, it is possible to prevent damage to cover 21 and leakage of gas from space 20 with a simple structure.

[0050] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0051] 11 battery cell, 12 exterior body, 13, 13j, 13k second side, 14, 14j, 14k first side, 15 top surface, 16 bottom surface, 17 gas outflow valve, 18 electrode terminal, 18N negative electrode terminal, 18P positive electrode terminal, 20, 20A, 20B space, 21 cover, 22 cover main body, 24 second flange, 26, 52 bolt, 30 opening, 31 case main body, 32 first side, 33 first flange, 34 rib portion, 35 gas flow hole, 36 second side, 41 plate member, 42 first portion, 46 second portion, 51 bottom, 61 cooling plate, 62 refrigerant passage, 66 bind bar, 70 duct, 71 duct cover, 72 gas flow passage, 91 end plate, 100 Battery pack, 110 virtual plane, 120 cell stack.

Claims

1. A plurality of battery cells; A case body having an opening; a cover attached to the case body so as to close the opening and forming, together with the case body, a space for accommodating the plurality of battery cells; a plate member made of metal or ceramic, the plate member having a first portion disposed in the space between the plurality of battery cells and the cover, and a second portion provided on the periphery of the first portion and sandwiched between the case body and the cover.

2. The battery cell includes: an exterior body including a top surface and a side surface and housing the electrode assembly and the electrolyte; a gas outlet valve that allows gas to flow from inside the exterior body through the top surface to the space when the pressure inside the exterior body reaches or exceeds a predetermined value, The first portion faces the top surface, and further The battery pack according to claim 1 , further comprising a duct provided opposite the side surface, forming a gas flow passage communicating with the space, and discharging the gas from the space.

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