Battery unit

Abstract

A battery unit (100) is provided with a plurality of cooling members (10) and a plurality of battery cells (20). Each of the cooling members (10) include a first member (11) and a second member (12). The first member (11) and the second member (12) are each formed of a metal plate. The second member (12), together with the first member (11), forms a space (13) into which a cooling liquid is supplied. Each of the battery cells (20) uses a metal can (21) as an exterior material. Each of the battery cells (20) is disposed between the space (13) of one of the cooling members (10) and the space (13) of another one of the cooling members (10). Each of the battery cells (20) is bonded to the first member (11) or the second member (12) in one of the cooling members (10) and / or another one of the cooling members (10).

Description

Battery unit

[0001] The present disclosure relates to a battery unit.

[0002] For example, electric vehicles are equipped with a battery unit including a plurality of battery cells, and large-capacity battery units are used in electric vehicles to ensure a sufficient distance (cruising range) that can be traveled solely on electricity.

[0003] A battery unit requires a cooling function for the battery cells to operate stably at an appropriate temperature. For example, Patent Document 1 discloses a technology in which a row of pouch-type battery cells is arranged between a pair of cooling plates. In Patent Document 1, each cooling plate is composed of two metal plates so as to have a cavity therein. A heat transfer fluid is supplied into the cavity of each cooling plate. Patent Document 1 describes that because the battery cells are in thermal contact with the cooling plates, heat exchange occurs between the battery cells and the heat transfer fluid, thereby lowering the temperature of the battery cells.

[0004] Patent No. 6125624

[0005] For example, when a battery unit is installed in an electric vehicle or the like, the battery unit is also required to have the function of protecting the battery cells in the event of a collision (crashworthiness). To ensure crashworthiness, a battery tray that houses the battery cells is often provided with a frame member. However, in a typical battery unit, the member for ensuring crashworthiness is provided separately from the member for ensuring cooling function. This can result in an increase in the number of parts in the battery unit and a complex structure.

[0006] An object of the present disclosure is to provide a battery unit including a member that is endowed with both cooling performance and collision resistance.

[0007] The battery unit according to the present disclosure includes a plurality of cooling members and a plurality of battery cells. Each of the plurality of cooling members includes a first member, a second member, an inlet, and an outlet. The first member is formed of a metal plate. The second member is formed of a metal plate. The second member is joined to the first member at their outer peripheries, and together with the first member, forms a space to which a coolant is supplied. The inlet is used to introduce the coolant into the space. The outlet is used to discharge the coolant from the space. Each of the plurality of battery cells has a metal can as an exterior material. The plurality of battery cells are arranged between a space of one of the cooling members and a space of another of the cooling members. Each of the plurality of battery cells is bonded to the first member or the second member of at least one of the one cooling member and the other cooling member.

[0008] According to the present disclosure, it is possible to provide both cooling performance and collision resistance performance to components within a battery unit.

[0009] FIG. 1 is a perspective view of a battery unit according to an embodiment. FIG. 2 is a cross-sectional view showing a portion of the battery unit shown in FIG. 1. FIG. 3 is a side view of a cooling member included in the battery unit shown in FIG. 1. FIG. 4 is another side view of the cooling member included in the battery unit shown in FIG. 1. FIG. 5 is a perspective view showing a portion of the battery unit shown in FIG. 1. FIG. 6 is a cross-sectional view of a cooling member included in the battery unit shown in FIG. 1. FIG. 7 is another cross-sectional view of the cooling member included in the battery unit shown in FIG. 1. FIG. 8 is a diagram showing the deformation behavior of a battery unit according to a comparative example. FIG. 9 is a diagram showing the deformation behavior of a battery unit according to an example. FIG. 10 is a load-displacement curve obtained by analysis.

[0010] A battery unit according to an embodiment includes a plurality of cooling members and a plurality of battery cells. Each of the plurality of cooling members includes a first member, a second member, an inlet, and an outlet. The first member is formed of a metal plate. The second member is formed of a metal plate. The second member is joined to the first member at its outer periphery and, together with the first member, forms a space to which a coolant is supplied. The inlet is used to introduce the coolant into the space. The outlet is used to discharge the coolant from the space. Each of the plurality of battery cells has a metal can as an exterior material. The plurality of battery cells are arranged between a space of one of the cooling members and a space of another of the cooling members. Each of the plurality of battery cells is bonded to the first member or the second member of at least one of the one cooling member and the other cooling member (first configuration).

[0011] The battery unit according to the first configuration includes a plurality of cooling members and a plurality of battery cells arranged between adjacent cooling members. Each battery cell is bonded to at least one of the adjacent cooling members at a position corresponding to the coolant space. Specifically, each battery cell is bonded to the first or second member of the cooling member. This reduces the likelihood of an air layer, which acts as an insulating layer, being interposed between the battery cell and the first or second member of the cooling member. This allows for good heat transfer between the cooling member, to which the coolant is supplied in the space between the first and second members, and the battery cells, thereby cooling the battery cells.

[0012] In the battery unit according to the first configuration, each battery cell has a metal can as an exterior material. That is, the battery cells are not flexible like pouch-type battery cells, but have relatively high rigidity. Therefore, each battery cell can be bonded to at least one cooling member to reinforce the cooling member. Therefore, when a collision load is applied to the battery unit, the cooling member is less likely to deform, and the battery cells bonded to the cooling member are less likely to be damaged.

[0013] In this way, according to the first configuration, it is possible to provide the cooling member in the battery unit with both cooling performance and collision resistance.

[0014] In the battery unit according to the first configuration, both longitudinal ends of each of the plurality of cooling members may protrude outward relative to the plurality of battery cells (second configuration).

[0015] In the second configuration, both longitudinal ends of the cooling member protrude outward beyond the battery cells arranged between the cooling members. In this case, when a collision load is input from either end of the cooling member, the end of the cooling member deforms preferentially to absorb the collision energy. This makes it less likely that the cooling member will deform at the positions of the battery cells, making it easier to prevent damage to the battery cells.

[0016] In a battery unit having the first or second configuration, it is preferable that, for each of the multiple cooling members, the cross-sectional area perpendicular to the longitudinal direction of the first member and the second member at both longitudinal ends of the cooling member is equal to the cross-sectional area perpendicular to the longitudinal direction of the first member and the second member at a position in space (third configuration).

[0017] In the third configuration, the cross-sectional areas of the first and second members (the areas of the cross sections perpendicular to the longitudinal direction of the cooling member) are equal to the cross-sectional areas of the first and second members at the position of the coolant space. By ensuring the cross-sectional areas of the first and second members at both longitudinal ends of each cooling member in this manner, when a collision load is input from either end of the cooling member, the first and second members can bear the collision load over a relatively wide area. This reduces the likelihood of local deformation of the cooling member, and better protects the battery cells attached to the cooling member.

[0018] In a battery unit having any of the first to third configurations, in each of the multiple cooling members, the inlet may be formed at one end in the longitudinal direction of the cooling member, and the outlet may be formed at the other end in the longitudinal direction (fourth configuration).

[0019] In the battery unit according to any one of the first to fourth configurations, the first member and the second member may each be formed from an aluminum-based plated steel plate (fifth configuration).

[0020] In the cooling member, a coolant is supplied to the space formed by the first member and the second member. Therefore, it is preferable that the first member and the second member have corrosion resistance against the coolant. Therefore, in the fifth configuration, the first member and the second member are each formed of an aluminum-based plated steel plate. This allows the first member and the second member to have high corrosion resistance against the coolant.

[0021] In the battery unit according to any one of the first to fourth configurations, the first member and the second member may each be formed of a zinc-based plated steel sheet, in which case it is preferable that a chemical conversion coating be formed on the surface of the zinc-based plated steel sheet (sixth configuration).

[0022] In the sixth configuration, each of the first member and the second member is formed of a zinc-based plated steel sheet having a chemical conversion coating on its surface, thereby providing the first member and the second member with high corrosion resistance against the coolant.

[0023] In the battery unit according to any one of the first to sixth configurations, the first member and the second member may have a Vickers hardness of 130 HV or more (seventh configuration).

[0024] In the seventh configuration, the Vickers hardness of the first member and the second member is 130 HV or more, which can further improve the impact resistance of the cooling member.

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In these drawings, the same or equivalent components are designated by the same reference numerals, and the same description will not be repeated.

[0026] 1 is a perspective view of a battery unit 100 according to this embodiment. The battery unit 100 is mounted on, for example, an electric vehicle.

[0027] Referring to FIG. 1 , a battery unit 100 includes a plurality of cooling members 10 , a plurality of battery cells 20 , a battery tray 30 , and a plurality of mounting members 40 .

[0028] The cooling members 10 are members for cooling the battery cells 20. Each cooling member 10 has an elongated shape. When the battery unit 100 is mounted on an electric vehicle, each cooling member 10 extends, for example, in the left-right direction or the front-rear direction of the vehicle body. In the example shown in Fig. 1, the cooling members 10 are arranged substantially parallel to each other.

[0029] The battery cells 20 are arranged between the cooling members 10. More specifically, between two adjacent cooling members 10, the battery cells 20 are arranged in one or two rows along the longitudinal direction of the cooling members 10. In the example of Fig. 1, two rows of battery cells 20 are provided between the two adjacent cooling members 10.

[0030] The battery tray 30 has, for example, a concave shape. Although not shown, a lid may be attached to the battery tray 30. The cooling member 10 and the battery cells 20 are housed in the battery tray 30. The cooling member 10 and the battery cells 20 are attached to a bottom plate of the battery tray 30 via, for example, attachment members 40. When the battery unit 100 is mounted on an electric vehicle, each of the attachment members 40 extends, for example, in the left-right direction or the front-rear direction of the vehicle body. In FIG. 1 , each of the attachment members 40 extends so as to intersect with the cooling member 10. The attachment members 40 may be fastened to the bottom plate of the battery tray 30.

[0031] 2 is a diagram (cross-sectional view) of the battery unit 100 cut along a plane perpendicular to the longitudinal direction of the cooling members 10. FIG. 2 shows two adjacent cooling members 10 and a battery cell 20 disposed between the cooling members 10.

[0032] 2, each cooling member 10 includes a first member 11 and a second member 12. The first member 11 and the second member 12 are each formed of a metal plate. The first member 11 and the second member 12 are joined at their outer peripheries to form a space 13 to which a coolant is supplied.

[0033] 3 is a side view of the cooling member 10, and is a view of the cooling member 10 seen from the side of the first member 11. Referring to FIG. 3, the first member 11 includes a top plate 111, a peripheral wall 112, and a flange 113.

[0034] The top plate 111 extends in the longitudinal direction of the cooling member 10. In this embodiment, the top plate 111 has a rounded rectangular shape (oval track shape) in a side view of the cooling member 10. However, the top plate 111 may have other shapes, such as a rectangular shape, in a side view of the cooling member 10. The flange 113 is provided on the first member 11 so as to surround the top plate 111 in a side view of the cooling member 10. The flange 113 forms the outer periphery of the first member 11. The peripheral wall 112 connects the top plate 111 to the flange 113 around its entire periphery.

[0035] The first member 11 includes an inlet 114 and an outlet 115. The inlet 114 is a hole for introducing the coolant into the space 13 ( FIG. 2 ). The outlet 115 is a hole for discharging the coolant from the space 13. For example, a long-life coolant (LLC) aqueous solution containing an organic component is used as the coolant.

[0036] In this embodiment, the inlet 114 and the outlet 115 are formed in the top plate 111. The inlet 114 and the outlet 115 are through holes that penetrate the top plate 111 in its thickness direction. The inlet 114 is formed at one end of the top plate 111 in the longitudinal direction of the cooling member 10. The outlet 115 is formed at the other end of the top plate 111 in the longitudinal direction of the cooling member 10.

[0037] 4 is a side view of the cooling member 10, as viewed from the side of the second member 12. Referring to FIG. 4, the second member 12 includes a top plate 121, a peripheral wall 122, and a flange 123.

[0038] The top plate 121 extends in the longitudinal direction of the cooling member 10. The top plate 121 preferably has a shape corresponding to the top plate 111 of the first member 11 ( FIG. 3 ). In this embodiment, the top plate 121 has a rounded rectangular shape (oval track shape) in a side view of the cooling member 10, similar to the top plate 111 of the first member 11. The flange 123 is provided on the second member 12 so as to surround the top plate 121 in a side view of the cooling member 10. The flange 123 forms the outer periphery of the second member 12. The peripheral wall 122 connects the top plate 121 to the flange 123 around its entire periphery.

[0039] The second member 12 includes an inlet 124 and an outlet 125. The inlet 124 is a hole for introducing the coolant into the space 13 (FIG. 2). The outlet 125 is a hole for discharging the coolant from the space 13.

[0040] In this embodiment, the inlet 124 and the outlet 125 are formed in the top plate 121. The inlet 124 and the outlet 125 are through-holes that penetrate the top plate 121 in its thickness direction. The inlet 124 is formed at one end of the top plate 121 in the longitudinal direction of the cooling member 10. The outlet 125 is formed at the other end of the top plate 121 in the longitudinal direction of the cooling member 10. The inlet 124 and the outlet 125 are disposed at positions corresponding to the inlet 114 and the outlet 115 ( FIG. 3 ) of the first member 11, respectively.

[0041] Returning to FIG. 2 , the first member 11 and the second member 12 form a closed cross section. The top plate 111 of the first member 11 faces the top plate 121 of the second member 12 with a gap therebetween. In this embodiment, the top plates 111 and 121 are each flat and arranged substantially parallel to each other. The top plate 111 and the peripheral wall 112 of the first member 11, together with the top plate 121 and the peripheral wall 122 of the second member 12, define a space 13 for the coolant. The flange 113 of the first member 11 is joined to a flange 123 of the second member 12 around the periphery of the space 13.

[0042] The flanges 113, 123 are joined in a liquid-tight manner. A sealer 14 may be used to join the flanges 113, 123. The sealer 14 is, for example, a coating agent whose main component is resin. A known sealer for ensuring liquid-tightness may be used as the sealer 14. The flanges 113, 123 may be joined using the sealer 14 in combination with spot welding or mechanical joining. Examples of mechanical joining include joining by partially caulking the flanges 113, 123 or joining using rivets, etc. Alternatively, the flanges 113, 123 may be joined by continuous welding such as laser welding or seam welding, brazing, or friction diffusion welding. The flanges 113, 123 may be joined using an adhesive. If the sealer 14 functions as an adhesive, the flanges 113, 123 can also be joined using the sealer 14 alone.

[0043] 2, the second member 12 further includes a flange 126. The flange 126 is provided contiguous with the flange 123. For example, when the battery unit 100 is mounted on an electric vehicle, the flange 126 is adjacent to the flange 123 on the lower end side of the cooling member 10 and extends in the longitudinal direction of the cooling member 10. The flange 126 is joined to the mounting member 40 (FIG. 1) by, for example, spot welding.

[0044] The multiple cooling members 10 are arranged such that the space 13 of each cooling member 10 faces the space 13 of another cooling member 10. Each cooling member 10 is arranged in parallel with the other cooling members 10. The multiple battery cells 20 are arranged between the space 13 of one cooling member 10 and the space 13 of the other cooling members 10. Each battery cell 20 is bonded to the first member 11 or the second member 12 of at least one of these cooling members 10. That is, the battery cell 20 is bonded to at least one of the cooling members 10 at the position of the space 13. In this embodiment, cell rows R1 and R2 are arranged between two adjacent cooling members 10. Each cell row R1 and R2 includes two or more battery cells 20 lined up in the longitudinal direction of the cooling member 10. The battery cells 20 of the cell row R1 are bonded to the second member 12 of one of the cooling members 10. The battery cells 20 of the cell row R2 are bonded to the first member 11 of the other cooling member 10 .

[0045] Each of the battery cells 20 is adhered to at least one cooling member 10 by an adhesive layer 50. The adhesive layer 50 is preferably made of a resin material with high thermal conductivity, for example, having a thermal conductivity of 1.0 W / m or more. The adhesive layer 50 can fill gaps that occur between the cooling member 10 and the battery cells 20. The adhesive layer 50 fills gaps that occur due to differences in shape between the cooling member 10 and the battery cells 20, as well as fine gaps that occur due to surface roughness between the cooling member 10 and the battery cells 20, for example. The adhesive layer 50 can be formed using a known adhesive or gap filler.

[0046] The battery cells 20 are, for example, lithium-ion battery cells. Each battery cell 20 has a metal can 21 as an exterior material. Specifically, the battery cells 20 are prismatic cells or cylindrical cells. In the example of this embodiment, the battery cells 20 are prismatic cells and have a rectangular parallelepiped metal can 21 as an exterior material. Although not shown, an electrode body, an electrolyte, etc. are accommodated inside the metal can 21. The metal can 21 is formed of, for example, an aluminum alloy plate.

[0047] When the battery cells 20 are prismatic cells, each of the battery cells 20 is arranged so that at least one side surface faces one of the cooling members 10. The side surface of the battery cell 20 is adhered to the cooling member 10. In the example of this embodiment, at least one side surface of the battery cell 20 faces the top plate 111 of the first member 11 or the top plate 121 of the second member 12, and is adhered to the top plate 111 or the top plate 121 by an adhesive layer 50.

[0048] The thickness W2 of the battery cell 20 is preferably equal to or greater than the thickness W1 of the cooling member 10. The thickness W2 of the battery cell 20 is, for example, 18.0 mm or greater and 80.0 mm or less. The thickness W1 of the cooling member 10 is, for example, 2.0 mm or greater and 10.0 mm or less. When the battery cell 20 is a rectangular cell, the thickness W2 of the battery cell 20 is the linear distance between the side surface facing the cooling member 10 and the side surface opposite the side surface. On the other hand, when the battery cell 20 is a cylindrical cell, the thickness W2 of the battery cell 20 is its diameter. The thickness W1 of the cooling member 10 is the maximum thickness of the cooling member 10 at the position of the space 13. In the example of this embodiment, the thickness W1 of the cooling member 10 is the distance from the top plate 111 of the first member 11 to the top plate 121 of the second member 12 in the thickness direction of the top plates 111 and 121 in the cross section of the battery unit 100. The thickness W3 of the adhesive layer 50, i.e., the distance from the battery cell 20 to the cooling member 10 in the thickness direction of the battery cell 20, is, for example, 0.1 mm or more and 8.0 mm or less, and preferably 0.5 mm or more and 3.0 mm or less.

[0049] Fig. 5 is a perspective view showing two adjacent cooling members 10 and a battery cell 20 arranged between the cooling members 10. As shown in Fig. 5, in this embodiment, both longitudinal end portions of each cooling member 10 protrude outward relative to the battery cell 20. That is, the length of each cooling member 10 in the longitudinal direction is greater than the length of each of the cell rows R1 and R2. At least a portion of the flanges 113 and 123 of the cooling member 10 protrudes from the battery cell 20 on both longitudinal sides.

[0050] 5 , on one side in the longitudinal direction of the cooling member 10, the coolant inlet ports 114, 124 are exposed from the battery cell 20. On the other side in the longitudinal direction of the cooling member 10, the coolant outlet ports 115, 125 are exposed from the battery cell 20.

[0051] In this embodiment, in each of the cooling members 10, the first member 11 and the second member 12 are provided with inlets 114 and 124, respectively. The first member 11 and the second member 12 are also provided with outlets 115 and 125, respectively. In this case, in adjacent cooling members 10, the inlet 114 of the first member 11 of one cooling member 10 can be connected to the inlet 124 of the second member 12 of the other cooling member 10 by piping. This allows the coolant, when supplied into the space 13 ( FIG. 2 ) of one cooling member 10, to flow through the piping into the space 13 of the other cooling member 10. Similarly, in adjacent cooling members 10, the outlet 115 of the first member 11 of one cooling member 10 can be connected to the outlet 125 of the second member 12 of the other cooling member 10 by piping.

[0052] Fig. 6 is a diagram (cross-sectional view) of the cooling member 10 cut at a plane perpendicular to the longitudinal direction at the position of an end in the longitudinal direction. Fig. 6 shows a cross section of the cooling member 10 at a position outside the inlet ports 114, 124 or the outlet ports 115, 125 (Fig. 5) in the longitudinal direction of the cooling member 10, where the first member 11 and the second member 12 are joined. Fig. 7 is a diagram (cross-sectional view) of the cooling member 10 cut at a plane perpendicular to the longitudinal direction at the position of the space 13.

[0053] 6 and 7 , the cross-sectional areas (cross-sectional areas) of the first member 11 and the second member 12 at both longitudinal ends of the cooling member 10 are substantially equal to the cross-sectional areas (cross-sectional areas) of the first member 11 and the second member 12 at the position of the space 13, respectively. The cross-sectional area of ​​the first member 11 at both longitudinal ends of the cooling member 10 being equal to the cross-sectional area of ​​the first member 11 at the position of the space 13 means that a portion of the first member 11 has not been intentionally removed at both ends of the cooling member 10. Similarly, the cross-sectional area of ​​the second member 12 at both longitudinal ends of the cooling member 10 being equal to the cross-sectional area of ​​the second member 12 at the position of the space 13 means that a portion of the second member 12 has not been intentionally removed at both ends of the cooling member 10. It is preferable that the first member 11 and the second member 12 have a substantially constant cross-sectional area over the entire longitudinal length of the cooling member 10. In this embodiment, the first member 11 and the second member 12 have a substantially rectangular shape when viewed from the side of the cooling member 10 (FIGS. 3 and 4).

[0054] In the cross section of the cooling member 10, when the length of the first member 11 in a direction perpendicular to the direction in which the first member 11 and the second member 12 are arranged is defined as a height H1 of the first member 11, the height H1 of the first member 11 is substantially the same at both longitudinal ends of the cooling member 10 and at the position of the space 13. When the length of the second member 12 in a direction perpendicular to the direction in which the first member 11 and the second member 12 are arranged is defined as a height H2 of the second member 12, the height H2 of the second member 12 is substantially the same at both longitudinal ends of the cooling member 10 and at the position of the space 13.

[0055] [Material of Battery Unit] In each of the cooling members 10, the first member 11 and the second member 12 are typically formed of steel plate to ensure their strength. The first member 11 and the second member 12 can be formed, for example, by press-forming a steel plate. The plate thickness of each of the first member 11 and the second member 12 is, for example, 0.4 mm or more and 2.0 mm or less, and preferably 0.8 mm or more and 1.4 mm or less. The plate thickness of the first member 11 is preferably the same as the plate thickness of the second member 12.

[0056] From the viewpoint of ensuring corrosion resistance against the coolant, the first member 11 and the second member 12 may each be formed of an aluminum-based plated steel sheet. The aluminum-based plated steel sheet is a steel sheet including a base steel sheet and an aluminum (Al)-based plating layer formed on the base steel sheet.

[0057] The Al-based plating layer is a plating layer containing Al. The Al-based plating layer contains, for example, 70% or more Al by mass. The Al-based plating layer is preferably a two-component or multi-component plating layer containing, by mass, 70 to 98% Al and 2 to 15% Si. From the viewpoint of further improving the workability and corrosion resistance of the aluminum-based plated steel sheet, the Si content of the Al-based plating layer is more preferably 3 to 15% by mass. The Al-based plating layer is formed on at least the surface of each of the first member 11 and the second member 12 that is located on the space 13 side. The Al-based plating layer may be formed on both surfaces of the first member 11 and / or both surfaces of the second member 12.

[0058] The Al-based plating layer may contain trace amounts of Fe, Ni, Co, etc. as impurity elements. The Al-based plating layer may contain Mg, Sn, misch metal, Sb, Zn, Cr, W, V, Mo, etc. as necessary. Although not particularly limited, the Al-based plating layer may be, for example, hot-dip flux plating, hot-dip plating formed by the Sendzimir method or the all-radiant method, electroplating, vapor deposition plating, etc.

[0059] In order to further enhance the corrosion resistance of the aluminum-based plated steel sheet, a chemical conversion coating may be formed on the surface of the aluminum-based plated steel sheet. The chemical conversion coating is formed on at least the surface of each of the first member 11 and the second member 12 that faces the space 13. The chemical conversion coating may be formed on both surfaces of the first member 11 and / or both surfaces of the second member 12.

[0060] The chemical conversion coating is a coating containing a Zr-based component, a Ti-based component, or a Si-based component as a main component. That is, the chemical conversion coating contains 50% or more by mass of a Zr-based component, a Ti-based component, or a Si-based component. The chemical conversion coating may also contain an organic component. As the chemical conversion coating applied to the aluminum-based plated steel sheet, for example, those described in International Publication No. 2022 / 185840 can be used. The chemical conversion coating can be formed, for example, by applying a Zr-based, Ti-based, or Si-based chemical conversion treatment solution (coating treatment solution) to the aluminum-based plated steel sheet by a known method, followed by baking and drying.

[0061] The first member 11 and the second member 12 may be formed of a zinc-based plated steel sheet instead of an aluminum-based plated steel sheet. The zinc-based plated steel sheet is a steel sheet including a base steel sheet and a zinc (Zn)-based plating layer formed on the base steel sheet. The Zn-based plating layer is a plating layer containing Zn. The Zn-based plating layer is formed on at least the surface of each of the first member 11 and the second member 12 that is located on the space 13 side. The Zn-based plating layer may be formed on both surfaces of the first member 11 and / or both surfaces of the second member 12.

[0062] Examples of zinc-based plated steel sheets include zinc-plated steel sheets, zinc-nickel-plated steel sheets, zinc-iron-plated steel sheets, zinc-chromium-plated steel sheets, zinc-aluminum-plated steel sheets, zinc-titanium-plated steel sheets, zinc-magnesium-plated steel sheets, zinc-manganese-plated steel sheets, zinc-aluminum-magnesium-plated steel sheets, zinc-aluminum-magnesium-silicon-plated steel sheets, etc. In these plated steel sheets, the Zn-based plating layer may contain small amounts of different metal elements or impurity elements such as Co, Mo, W, Ni, Ti, Cr, Al, Mn, Fe, Mg, Pb, Bi, Sb, Sn, Cu, Cd, As, etc., and may also have inorganic substances such as silica, alumina, titania, etc. dispersed therein.

[0063] The Zn-based plating layer may be used in combination with other plating layers. That is, the zinc-based plated steel sheet may have a multi-layer plating that combines a Zn-based plating layer with a plating layer such as iron plating, iron-phosphorus plating, nickel plating, or cobalt plating. Methods for forming the Zn-based plating layer and other plating layers include, but are not limited to, electroplating, hot-dip plating, vapor deposition plating, dispersion plating, vacuum plating, and the like.

[0064] A chemical conversion coating is formed on the surface of the zinc-based plated steel sheet. The chemical conversion coating is formed on at least the surface of each of the first member 11 and the second member 12 that faces the space 13. The chemical conversion coating may be formed on both surfaces of the first member 11 and / or both surfaces of the second member 12.

[0065] The chemical conversion coating is an inorganic coating or a resin coating. The inorganic coating is a coating containing a Si-based component or a Zr-based component as a main component. That is, the inorganic coating contains 50% or more by mass of the Si-based component or the Zr-based component. The inorganic coating may also contain an organic component. For example, an inorganic coating or a resin coating as a chemical conversion coating described in WO 2022 / 185849 can be used for the zinc-based plated steel sheet.

[0066] Although not particularly limited, the chemical conversion coating can be formed by applying an inorganic or resin-based chemical conversion treatment solution (coating treatment solution) to a zinc-based plated steel sheet by a known method, followed by baking and drying. A preferred combination of a zinc-based plated steel sheet and a chemical conversion coating is, for example, a combination of a zinc-aluminum-magnesium plated steel sheet and an inorganic coating containing a Si-based component as a main component. Another preferred example of a combination is a combination of a zinc-aluminum plated steel sheet and a resin coating.

[0067] In the aluminum-based plated steel sheet and the zinc-based plated steel sheet, the material of the base steel sheet is not particularly limited, and may be, for example, IF steel containing Ti, Nb, B, or the like, Al-k steel, Cr-added steel, stainless steel, high-tensile steel, low-carbon steel, medium-carbon steel, high-carbon steel, alloy steel, or the like.

[0068] In the cooling member 10, the first member 11 and the second member 12 preferably have a Vickers hardness of 130 HV or more. The first member 11 and the second member 12 more preferably have a Vickers hardness of 170 HV or more, and even more preferably have a Vickers hardness of 230 HV or more. The Vickers hardness of the first member 11 and the second member 12 is, for example, 500 HV or less. The Vickers hardness of the first member 11 and the second member 12 can be measured by a Vickers hardness test specified in JIS Z 2244-1:2020. Specifically, first, test pieces of a size suitable for the Vickers hardness test are obtained from any position of the first member 11 and the second member 12 by laser cutting or the like. Next, each test piece of the first member 11 and the second member 12 is embedded in resin so that its cross section is located on the surface, and the cross section is polished. Then, at any position in the thickness direction of this cross section, for example, at or near the center in the thickness direction, the Vickers hardness is measured in accordance with JIS Z 2244-1:2020 with a test force of 300 gf (2.9 N). The tensile strength (MPa) of each of the first member 11 and the second member 12 is approximately 3.3 times the Vickers hardness.

[0069] [Effects] In the battery unit 100 according to this embodiment, each of the battery cells 20 is bonded to at least one cooling member 10 at a position in the space 13 to which the coolant is supplied. The battery cells 20 are bonded to the first member 11 or the second member 12 of the cooling member 10 by an adhesive layer 50. The adhesive layer 50 preferably has high thermal conductivity. The adhesive layer 50 is made of a resin material having a thermal conductivity of, for example, 1.0 W / m or more. The adhesive layer 50 fills the gap between the battery cells 20 and the cooling member 10. This makes it difficult for an air layer to be interposed between the battery cells 20 and the cooling member 10, resulting in good heat transfer between the cooling member 10 and the battery cells 20. Therefore, the battery cells 20 are cooled by the cooling member 10 to which the coolant is supplied.

[0070] In the battery unit 100 according to this embodiment, each of the battery cells 20 has a metal can 21 as an exterior material, and therefore has higher rigidity than a pouch-type battery cell. Therefore, the battery cells 20 can reinforce the cooling member 10 to which they are adhered. Furthermore, battery cells 20 having a metal can 21 as an exterior material typically have a greater thickness W2 than pouch-type battery cells, and therefore can further reinforce the cooling member 10. By adhering the highly rigid battery cells 20 to the cooling member 10 and stiffening the cooling member 10, the cooling member 10 is less likely to deform when a collision load is input to the battery unit 10. As a result, the battery cells 20 adhered to the cooling member 10 are less likely to be damaged.

[0071] In this way, according to the battery unit 100 according to this embodiment, the cooling member 10 can exhibit not only the performance of cooling the battery cells 20 but also the crash resistance performance.

[0072] In the battery unit 100 according to this embodiment, a plurality of battery cells 20 are disposed between adjacent cooling members 10. Both longitudinal ends of each cooling member 10 protrude outward relative to the battery cells 20. In this case, the battery cells 20 are more likely to be protected. Specifically, when a collision load is input to the battery unit 100 from either longitudinal end of the cooling member 10, the end of the cooling member 10 deforms preferentially in the portion facing the battery cell 20. Specifically, the flange 113 of the first member 11 and the flange 123 of the second member 12 deform preferentially upon receiving the collision load, absorbing the collision energy. Therefore, the portion of the cooling member 10 adjacent to the battery cell 20 is less likely to deform, making the battery cell 20 less likely to be damaged.

[0073] In the battery unit 100 according to this embodiment, in each cooling member 10, the cross-sectional area of ​​the first member 11 at both longitudinal ends is equal to the cross-sectional area of ​​the first member 11 at the position of the space 13. Furthermore, in each cooling member 10, the cross-sectional area of ​​the second member 12 at both longitudinal ends is also equal to the cross-sectional area of ​​the second member 12 at the position of the space 13. That is, the first member 11 and the second member 12 are not partially cut away at both ends of each cooling member 10, ensuring a wide cross-sectional area for the first member 11 and the second member 12. Therefore, when a collision load is input from either longitudinal end of the cooling member 10, the first member 11 and the second member 12 can bear the collision load over a wide area. This makes it difficult for the cooling member 10 to undergo local deformation, and the battery cells 20 are more easily protected.

[0074] In the battery unit 100 according to this embodiment, the first member 11 and the second member 12 of each cooling member 10 are preferably formed of aluminum-based plated steel sheet. At least the surfaces of the first member 11 and the second member 12 facing the space 13 are preferably provided with an Al-based plating layer over the entire surface. This suppresses corrosion of the first member 11 and the second member 12 due to the coolant. By suppressing corrosion of the first member 11 and the second member 12, a decrease in the thermal conductivity of the first member 11 and the second member 12 and elution of components of the first member 11 and the second member 12 into the coolant are less likely to occur.

[0075] In the battery unit 100 according to this embodiment, the first member 11 and the second member 12 of each cooling member 10 may be formed of a zinc-based plated steel sheet. In this case, a chemical conversion coating is preferably formed on the surface of the zinc-based plated steel sheet. At least the entire surface of each of the first member 11 and the second member 12 facing the space 13 is preferably provided with a zinc-based plating layer, and this zinc-based plating layer is preferably covered with a chemical conversion coating. This makes it easier to suppress corrosion of the first member 11 and the second member 12 due to the coolant. This reduces the thermal conductivity of the first member 11 and the second member 12 and the elution of components of the first member 11 and the second member 12 into the coolant.

[0076] In the battery unit 100 according to this embodiment, the first member 11 and the second member 12 of each cooling member 10 preferably have a Vickers hardness of 130 HV or more, which allows the cooling member 10 to exhibit higher crash resistance.

[0077] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0078] In the above embodiment, all of the cooling members 10 included in the battery unit 100 extend in the same direction. However, it is not necessary that all of the cooling members 10 extend in the same direction. For example, when the battery unit 100 is mounted on an electric vehicle, some of the cooling members 10 may extend in the left-right direction of the vehicle body, and the remaining cooling members 10 may extend in the front-rear direction of the vehicle body. Even in this case, multiple battery cells 20 are arranged between adjacent cooling members 10 and are bonded to the first member 11 or the second member 12 of at least one of the cooling members 10.

[0079] In the above embodiment, the top plate 111, the peripheral wall 112, and the flange 113 of the first member 11 have shapes that are substantially symmetrical to the top plate 121, the peripheral wall 122, and the flange 123 of the second member 12 in a cross-sectional view of the battery unit 100. However, the first member 11 and the second member 12 do not necessarily have to have symmetrical shapes in a cross-sectional view. The first member 11 and the second member 12 only need to form a space 13 for the coolant. For example, one of the first member 11 and the second member 12 may have a top plate, a peripheral wall, and a flange as in the above embodiment, and the other of the first member 11 and the second member 12 may have a flat plate shape as a whole. However, when battery cells 20 are arranged on both sides of the cooling member 10, it is preferable that the first member 11 and the second member 12 have symmetrical cross-sectional shapes as in the above embodiment, from the viewpoint of cooling these battery cells 20 as uniformly as possible.

[0080] In the above embodiment, the inlets 114, 124 for the coolant are formed at one end in the longitudinal direction of each cooling member 10, and the outlets 115, 125 are formed at the other end in the longitudinal direction of each cooling member 10. However, the positions of the inlets 114, 124 and the outlets 115, 125 are not limited to this. The positions of the inlets 114, 124 and the outlets 115, 125 can be changed as appropriate depending on, for example, the shape of the cooling member 10, the positional relationship between the cooling member 10 and the battery cells 20, etc.

[0081] In the above embodiment, in each of the cooling members 10, the inlet 114 and the outlet 115 are provided in the first member 11, and the inlet 124 and the outlet 125 are also provided in the second member 12. However, in at least one of the cooling members 10, the coolant inlet may be provided in only one of the first member 11 and the second member 12. For example, among the cooling members 10 lined up in the left-right direction or the front-rear direction of the vehicle body, the cooling member 10 located at the end may have a coolant inlet in only one of the first member 11 and the second member 12.

[0082] Similarly, in at least one of the cooling members 10, an outlet for the coolant may be provided in only one of the first member 11 and the second member 12. For example, among the cooling members 10 lined up in the left-right direction or the front-rear direction of the vehicle body, the cooling member 10 located at the end may have an outlet for the coolant in only one of the first member 11 and the second member 12.

[0083] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to the following examples.

[0084] To confirm the effects of the present disclosure, an analysis was performed using general-purpose structural analysis software (LS-DYNA, manufactured by Ansys). In this analysis, as an example, a battery unit including multiple cooling members 10, multiple prismatic battery cells 20, and multiple mounting members 40, similar to the above embodiment, was subjected to a pole-shaped collision object colliding with the cooling member 10 from the longitudinal direction to confirm deformation of the cooling member 10. Additionally, as a comparative example, a similar analysis was performed on a battery unit omitting the prismatic battery cells 20. In each of the example and comparative example, the tensile strength of each cooling member 10 was 590 MPa, the plate thickness was 1.0 mm, and the tensile strength of each mounting member 40 was 1.5 GPa, and the plate thickness was 1.6 mm.

[0085] Fig. 8 is a diagram showing the deformation behavior of the battery unit according to the comparative example. Fig. 9 is a diagram showing the deformation behavior of the battery unit according to the example. Fig. 10 is a load-displacement curve obtained by analysis. In Fig. 10, the loads of the example and comparative example are normalized by the maximum load of the example.

[0086] As shown in Fig. 8, in the comparative example, the battery cells 20 were not present and the cooling members 10 were not stiffened by the battery cells 20, resulting in the cooling members 10 being bent overall at the collision position of the battery unit and in the vicinity thereof. Therefore, as shown in Fig. 10, in the comparative example, the load on the battery unit during a collision was overall low.

[0087] On the other hand, as shown in Fig. 9, in the example, the battery cells 20 were adhered to each cooling member 10, and each cooling member 10 was stiffened by the battery cells 20, so the portions of the cooling members 10 corresponding to the battery cells 20 were hardly deformed. Therefore, as shown in Fig. 10, the load on the battery unit in the example during a collision was clearly higher than that of the comparative example. In other words, the battery unit according to the example had improved collision resistance performance compared to the battery unit according to the comparative example.

[0088] As shown in Figure 9, in the embodiment, the ends of each cooling member 10 protruded outward in the longitudinal direction beyond the battery cells 20, so that the ends of each cooling member 10 deformed before the battery cells 20 and absorbed the collision energy.

[0089] This analysis confirmed that the ends of each cooling member 10 deform before the battery cells 20, absorbing the collision energy, and that the battery cells 20 are attached to each cooling member 10, reinforcing each cooling member 10 with the battery cells 20, thereby significantly increasing the load on the battery unit during a collision, thereby contributing to collision resistance.

[0090] 100: Battery unit 10: Cooling member 11: First member 114: Inlet 115: Outlet 12: Second member 124: Inlet 125: Outlet 13: Space 20: Battery cell 21: Metal can

Claims

1. A battery unit comprising: a first member formed of a metal plate; a second member formed of a metal plate and joined to the first member at their outer peripheries to form a space to which coolant is supplied together with the first member; a plurality of cooling members each including an inlet for introducing the coolant into the space and an outlet for discharging the coolant from the space; and a plurality of battery cells each having a metal can as an exterior material, wherein the plurality of battery cells are arranged between the space of one of the cooling members and the space of another of the cooling members, and are each adhered to the first member or the second member of at least one of the one cooling member and the other cooling members.

2. A battery unit as claimed in claim 1, wherein both longitudinal ends of each of said plurality of cooling members protrude outward relative to said plurality of battery cells.

3. A battery unit as described in claim 1, wherein, in each of the plurality of cooling members, the cross-sectional areas perpendicular to the longitudinal direction of the first member and the second member at both longitudinal ends of the cooling member are equal to the cross-sectional areas perpendicular to the longitudinal direction of the first member and the second member at a position in the space.

4. A battery unit as described in claim 1, wherein in each of the plurality of cooling members, the inlet is formed at one end in the longitudinal direction of the cooling member, and the outlet is formed at the other end in the longitudinal direction.

5. A battery unit according to claim 1, wherein the first member and the second member are each formed of an aluminum-based plated steel plate.

6. A battery unit as claimed in claim 1, wherein the first member and the second member are each formed of a zinc-based plated steel sheet, and a chemical conversion coating is formed on the surface of the zinc-based plated steel sheet.

7. A battery unit according to any one of claims 1 to 6, wherein the first member and the second member have a Vickers hardness of 130 HV or more.

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