Battery unit

Abstract

The battery unit (100) includes a plurality of cooling members (10) and a plurality of battery cells (20). 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 second member (12), together with the first member (11), forms a space (13) to which a coolant is supplied. Each battery cell (20) has a metal can (21) as an exterior material. The battery cell (20) is disposed between the space (13) of one cooling member (10) and the space (13) of another cooling member (10). Each battery cell (20) is bonded to the first member (11) or the second member (12) of at least one of the one cooling member (10) and the other cooling member (10).

Description

Technical Field

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

Background Art

[0002] For example, an electric vehicle is equipped with a battery unit including a plurality of battery cells. In an electric vehicle, a large-capacity battery unit is used to ensure a driving distance (endurance) that can be traveled only by electricity.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, when a battery unit is mounted on an electric vehicle or the like, the battery unit is also required to have a function (crashworthiness) of protecting battery cells during a collision. In order to ensure the crashworthiness, a skeleton member is often provided on a battery tray that houses the battery cells. However, in a general battery unit, members for ensuring crashworthiness are provided separately from members for ensuring a cooling function. Therefore, in the battery unit, an increase in the number of parts and a complication of the structure may occur.

[0006] An object of the present disclosure is to provide a battery unit including a member provided with both cooling performance and crashworthiness.

Means for Solving the Problems

[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 peripheral portions to form a space into which a coolant is supplied together with the first member. 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 the space of one cooling member and the space of another cooling member among the cooling members. Each of the plurality of battery cells is adhered to the first member or the second member in at least one of one cooling member and another cooling member.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to impart both cooling performance and crashworthiness to the members in the battery unit.

Brief Description of the Drawings

[0009]

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DETAILED DESCRIPTION OF THE INVENTION

[0010] The battery unit according to the 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 their outer peripheral portions to form a space into which a coolant is supplied together with the first member. 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 the space of one cooling member and the space of another cooling member among the cooling members. Each of the plurality of battery cells is adhered to at least one of the first member or the second member in 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 disposed between adjacent cooling members. Each of the battery cells is adhered to at least one of the adjacent cooling members at the position of the space for the coolant. Specifically, each of the battery cells is adhered to the first member or the second member of the cooling member. As a result, it becomes difficult for an air layer, which is a heat insulating layer, to intervene between the battery cell and the first member or the second member of the cooling member. Therefore, good heat transfer can occur between the cooling member supplied with the coolant in the space between the first member and the second member and the battery cell, and the battery cell can be cooled.

[0012] In the battery unit according to the first configuration, each of the battery cells has a metal can as an exterior material. That is, the battery cells do not have flexibility like pouch-type battery cells and have relatively large rigidity. Therefore, each of the battery cells can reinforce the cooling member by being adhered to at least one cooling member. Accordingly, when a collision load is input to the battery unit, it becomes difficult for the cooling member to deform, and damage to the battery cells adhered to the cooling member is also less likely to occur.

[0013] Thus, according to the first configuration, it is possible to impart both cooling performance and collision resistance performance to the cooling member in the battery unit.

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

[0015] In the second configuration, both longitudinal ends of the cooling member protrude outward more than the battery cells disposed 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 can preferentially deform and absorb the collision energy. Therefore, deformation of the cooling member at the position of the battery cell is less likely to occur, and damage to the battery cell is more easily prevented.

[0016] In the battery unit according to the first or second configuration, in each of the plurality of cooling members, it is preferable that the areas of the cross-sections perpendicular to the longitudinal direction of the first member and the second member at both end portions in the longitudinal direction of the cooling member are respectively equal to the areas of the cross-sections perpendicular to the longitudinal direction of the first member and the second member at the position in the space (third configuration).

[0017] In the third configuration, the cross-sectional areas of the first member and the second member (the areas of the cross-sections perpendicular to the longitudinal direction of the cooling member) are respectively equal to the cross-sectional areas of the first member and the second member at the position in the space for the coolant. By ensuring the cross-sectional areas of the first member and the second member at both end portions in the longitudinal direction of each cooling member in this way, when an impact load is input from either end portion of the cooling member, the first member and the second member can bear the impact load with a relatively large area. Therefore, local deformation of the cooling member is less likely to occur, and the battery cells adhered to the cooling member are more easily protected.

[0018] In the battery unit according to any one of the first to third configurations, in each of the plurality of cooling members, the inlet may be formed at one end portion in the longitudinal direction of the cooling member, and the outlet may be formed at the other end portion 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 of an aluminum-based plated steel sheet (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. Thus, in the fifth configuration, each of the first member and the second member is formed of an aluminum-based plated steel sheet. Thereby, the first member and the second member can 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 this case, it is preferable that a chemical conversion coating film is 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 film on its surface. Thereby, the first member and the second member can have 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 can 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. Thereby, the impact resistance performance of the cooling member can be further enhanced.

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

[0026] [Structure of Battery Unit] FIG. 1 is a perspective view of a battery unit 100 according to the present embodiment. The battery unit 100 is mounted on, for example, an electric vehicle.

[0027] Referring to FIG. 1, the 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 member 10 is a member for cooling the battery cell 20. Each of the cooling members 10 has an elongated shape. When the battery unit 100 is mounted on an electric vehicle, each of the cooling members 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 in parallel.

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

[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 cell 20 are accommodated in the battery tray 30. The cooling member 10 and the battery cell 20 are attached to the bottom plate of the battery tray 30 via, for example, the attachment member 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 the cooling member 10. The attachment member 40 may be fastened to the bottom plate of the battery tray 30.

[0031] FIG. 2 is a view (cross - sectional view) obtained by cutting the battery unit 100 in a plane perpendicular to the longitudinal direction of the cooling member 10. In FIG. 2, two adjacent cooling members 10 and the battery cell 20 disposed between the cooling members 10 are shown.

[0032] Referring to FIG. 2, each of the cooling members 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 peripheral portions to form a space 13 to which a coolant is supplied.

[0033] FIG. 3 is a side view of the cooling member 10 and is a view of the cooling member 10 as 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 the present embodiment, the top plate 111 has an oval track shape (rounded rectangular shape) in a side view of the cooling member 10. However, the top plate 111 may have other shapes such as, for example, 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 constitutes the outer peripheral portion of the first member 11. The peripheral wall 112 connects the top plate 111 to the flange 113 over its entire circumference.

[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. As the coolant, for example, a long-life coolant (LLC) aqueous solution containing an organic component is used.

[0036] In the present 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 plate 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] FIG. 4 is a side view of the cooling member 10 and is a view of the cooling member 10 as seen 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 (FIG. 3) of the first member 11. In the present embodiment, the top plate 121 has an oval track shape, which is a rounded rectangular 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 peripheral portion of the second member 12. The peripheral wall 122 connects the top plate 121 to the flange 123 over its entire circumference.

[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 the present 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 plate 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 respectively arranged at positions corresponding to the inlet 114 and the outlet 115 (FIG. 3) of the first member 11.

[0041] Returning to FIG. 2, the first member 11 and the second member 12 together 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 the present embodiment, the top plates 111 and 121 each have a flat plate shape and are 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 the flange 123 of the second member 12 around the space 13.

[0042] The flanges 113, 123 are joined in a liquid-tight manner. A sealer 14 may be used for joining the flanges 113, 123. The sealer 14 is, for example, a coating agent mainly composed of a resin. As the sealer 14, those known as sealers for ensuring liquid tightness can be used. The flanges 113, 123 may be joined by 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 and joining using rivets or the like. Alternatively, the flanges 113, 123 may be joined by continuous welding such as laser welding or seam welding, brazing, or friction stir welding. The flanges 113, 123 may be joined by an adhesive. When the sealer 14 functions as an adhesive, the flanges 113, 123 can also be joined only by the sealer 14.

[0043] In the example of FIG. 2, the second member 12 further includes a flange 126. The flange 126 is provided continuously with the flange 123. For example, in a state where 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 attachment member 40 (FIG. 1) by, for example, spot welding or the like.

[0044] The plurality of cooling members 10 are arranged such that the spaces 13 of each cooling member 10 face the spaces 13 of other cooling members 10. Each of the cooling members 10 is arranged in parallel with the other cooling members 10. The plurality of battery cells 20 are arranged between the space 13 of one cooling member 10 and the space 13 of another cooling member 10. Each of the battery cells 20 is adhered to the first member 11 or the second member 12 in at least one of these cooling members 10. That is, the battery cell 20 is adhered at the position of the space 13 with respect to at least one of the cooling members 10. In the present embodiment, cell rows R1 and R2 are arranged between two adjacent cooling members 10. The cell rows R1 and R2 each include two or more battery cells 20 arranged in the longitudinal direction of the cooling member 10. The battery cells 20 of the cell row R1 are adhered to the second member 12 of one cooling member 10. The battery cells 20 of the cell row R2 are adhered 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 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 the gap generated between the cooling member 10 and the battery cell 20. The adhesive layer 50 fills not only the gap caused by, for example, the difference in the shapes of the cooling member 10 and the battery cell 20, but also the fine gaps caused by the surface roughness of the cooling member 10 and the battery cell 20. The adhesive layer 50 can be formed using a known adhesive or gap filler.

[0046] The battery cell 20 is, for example, a lithium-ion battery cell. Each of the battery cells 20 has a metal can 21 as an exterior material. Specifically, the battery cell 20 is a square cell or a cylindrical cell. In the example of the present embodiment, the battery cell 20 is a square cell and has a rectangular parallelepiped-shaped metal can 21 as an exterior material. Although not shown, an electrode body, an electrolytic solution, etc. are housed in the metal can 21. The metal can 21 is formed of, for example, an aluminum alloy plate.

[0047] When the battery cell 20 is a rectangular cell, each of the battery cells 20 is arranged such that at least one side faces any of the cooling members 10. The said side of the battery cell 20 is adhered to the cooling member 10. In the example of this embodiment, at least one side 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 the 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 more and 80.0 mm or less. The thickness W1 of the cooling member 10 is, for example, 2.0 mm or more 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 facing the cooling member 10 and the opposite side. 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 in the plate thickness direction of the top plates 111, 121 from the top plate 111 of the first member 11 to the top plate 121 of the second member 12 in the cross section of the battery unit 100. The thickness W3 of the adhesive layer 50, that is, the distance in the thickness direction of the battery cell 20 from the battery cell 20 to the cooling member 10 is, for example, 0.1 mm or more and 8.0 mm or less, 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 ends of each of the cooling members 10 protrude outward with respect to the battery cell 20. That is, in the longitudinal direction of the cooling member 10, the length of each of the cooling members 10 is greater than the length of each of the cell rows R1, R2. At least a part of the flanges 113, 123 of the cooling member 10 protrudes from both sides in the longitudinal direction of the battery cell 20.

[0050] 5, on one side in the longitudinal direction of the cooling member 10, inlet ports 114, 124 for the coolant are exposed from the battery cell 20. On the other side in the longitudinal direction of the cooling member 10, outlet ports 115, 125 for the coolant 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. Furthermore, the first member 11 and the second member 12 are 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 pass through the piping and flow 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 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 the cross section of cooling member 10 at a position outside inlet ports 114, 124 or outlet ports 115, 125 (Fig. 5) in the longitudinal direction of cooling member 10, where first member 11 and second member 12 are joined. Fig. 7 is a diagram (cross-sectional view) of cooling member 10 cut at a plane perpendicular to the longitudinal direction at the position of space 13.

[0053] As shown in FIGS. 6 and 7, the areas of the cross-sections (cross-sectional areas) of the first member 11 and the second member 12 perpendicular to the longitudinal direction at both longitudinal ends of the cooling member 10 are substantially equal to the areas of the cross-sections (cross-sectional areas) of the first member 11 and the second member 12 perpendicular to the longitudinal direction at the position of the space 13, respectively. That the cross-sectional area of the first member 11 at both longitudinal ends of the cooling member 10 is equal to the cross-sectional area of the first member 11 at the position of the space 13 means that a part of the first member 11 is not intentionally cut off at both ends of the cooling member 10. Similarly, that the cross-sectional area of the second member 12 at both longitudinal ends of the cooling member 10 is equal to the cross-sectional area of the second member 12 at the position of the space 13 means that a part of the second member 12 is not intentionally cut off at both ends of the cooling member 10. The first member 11 and the second member 12 preferably have a substantially constant cross-sectional area over the entire longitudinal length of the cooling member 10. In the example of the present embodiment, the first member 11 and the second member 12 are substantially rectangular in a side view (FIGS. 3 and 4) of the cooling member 10.

[0054] 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 in the cross-section of the cooling member 10 is defined as the 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 in the cross-section of the cooling member 10 is defined as the 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 the battery unit] In each of the cooling members 10, the first member 11 and the second member 12 are typically formed of steel plates in order to ensure their strength. The first member 11 and the second member 12 can be formed, for example, by press-forming steel plates. The respective plate thicknesses of the first member 11 and the second member 12 are, for example, 0.4 mm or more and 2.0 mm or less, 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 of Al by mass%. The Al-based plating layer is preferably a two-component or multi-component plating layer containing Al: 70 to 98% and Si: 2 to 15% by mass%. From the viewpoint of further enhancing 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 located on the space 13 side in each of the first member 11 and the second member 12. 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. To the Al-based plating layer, Mg, Sn, mischmetal, Sb, Zn, Cr, W, V, Mo, etc. may be added as required. Although not particularly limited, the Al-based plating layer may be, for example, molten flux plating, molten plating formed by the Sendzimir method, the all-radiant method, etc., electroplating, or vapor deposition plating.

[0059] 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 located on the space 13 side in each of the first member 11 and the second member 12. 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 an Si-based component as a main component. That is, the chemical conversion coating contains 50% or more of a Zr-based component, a Ti-based component, or an Si-based component by mass%. The chemical conversion coating may 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 solution (coating treatment solution) to the aluminum-based plated steel sheet by a known method and baking and drying it.

[0061] The first member 11 and the second member 12 may be formed of a zinc-based plated steel sheet instead of the 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 located on the space 13 side in each of the first member 11 and the second member 12. 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 the zinc-based plated steel sheet include a zinc-plated steel sheet, a zinc-nickel plated steel sheet, a zinc-iron plated steel sheet, a zinc-chromium plated steel sheet, a zinc-aluminum plated steel sheet, a zinc-titanium plated steel sheet, a zinc-magnesium plated steel sheet, a zinc-manganese plated steel sheet, a zinc-aluminum-magnesium plated steel sheet, a zinc-aluminum-magnesium-silicon plated steel sheet, and the like. In these plated steel sheets, the Zn-based plating layer may contain Co, Mo, W, Ni, Ti, Cr, Al, Mn, Fe, Mg, Pb, Bi, Sb, Sn, Cu, Cd, As, etc. as a small amount of heterogeneous metal elements or impurity elements, or inorganic substances such as silica, alumina, and titania may be 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 can have a multi-layer plating combining a Zn-based plating layer and a plating layer such as iron plating, iron-phosphorus plating, nickel plating, or cobalt plating. Although not particularly limited, examples of the method for forming the Zn-based plating layer and other plating layers include electroplating, hot dipping, vapor deposition plating, dispersion plating, and vacuum plating.

[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 located on the space 13 side in each of the first member 11 and the second member 12. The chemical conversion coating may be formed on both sides of the first member 11 and / or both sides 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 an Si-based component or a Zr-based component as a main component. That is, the inorganic coating contains 50% or more of an Si-based component or a Zr-based component by mass%. The inorganic coating may contain an organic component. For the zinc-based plated steel sheet, for example, an inorganic coating or a resin coating as a chemical conversion coating described in International Publication No. 2022 / 185849 can be used.

[0066] Although not particularly limited, the chemical conversion coating can be formed by applying an inorganic or resin-based chemical conversion treatment liquid (coating treatment liquid) to the zinc-based plated steel sheet by a known method and baking and drying it. A preferable combination of the zinc-based plated steel sheet and the chemical conversion coating is, for example, a combination of a zinc-aluminum-magnesium plated steel sheet and an inorganic coating containing an Si-based component as a main component. Another example of a preferable 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. The material of the base steel sheet may be, for example, IF steel, Al-k steel, Cr-added steel, stainless steel, high-tensile steel, low-carbon steel, medium-carbon steel, high-carbon steel, alloy steel, etc. added with Ti, Nb, B, etc.

[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 still more preferably 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 the Vickers hardness test defined in JIS Z 2244-1:2020. Specifically, first, test pieces of a size suitable for the Vickers hardness test are obtained from an arbitrary position of the first member 11 and the second member 12 by laser cutting or the like. Next, each test piece is embedded in resin so that the cross section of each of the first member 11 and the second member 12 is disposed on the surface, and the cross section is polished. Then, at an arbitrary position in the plate thickness direction of this cross section, for example, at the center of the plate thickness direction or in the vicinity thereof, in accordance with JIS Z 2244-1:2020, the Vickers hardness is measured 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 about 3.3 times its Vickers hardness.

[0069] [Effect] In the battery unit 100 according to the present embodiment, each of the battery cells 20 is adhered to at least one cooling member 10 at the position of a space 13 to which a coolant is supplied. The battery cell 20 is adhered 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 a resin material having a thermal conductivity of, for example, 1.0 W / m or more. The adhesive layer 50 is filled in the gap between the battery cell 20 and the cooling member 10. Therefore, an air layer is less likely to intervene between the battery cell 20 and the cooling member 10, and good heat transfer occurs between the cooling member 10 and the battery cell 20. Accordingly, the battery cell 20 is cooled by the cooling member 10 to which the coolant is supplied.

[0070] In the battery unit 100 according to the present embodiment, each of the battery cells 20 has high rigidity compared to a pouch-type battery cell because it has a metal can 21 as an exterior material. Therefore, the battery cell 20 can reinforce the cooling member 10 to which it is adhered. Further, since the battery cell 20 having the metal can 21 as an exterior material usually has a larger thickness W2 compared to a pouch-type battery cell, the cooling member 10 can be more effectively reinforced. When a high-rigidity battery cell 20 is adhered to the cooling member 10 and the cooling member 10 is reinforced, the cooling member 10 is less likely to be deformed when a collision load is input to the battery unit 100. As a result, damage to the battery cell 20 adhered to the cooling member 10 is also less likely to occur.

[0071] As described above, according to the battery unit 100 according to the present embodiment, the cooling member 10 can exhibit not only the cooling performance of the battery cell 20 but also the collision resistance performance.

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

[0073] In the battery unit 100 according to the present 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. Also, in each cooling member 10, the cross-sectional area of the second member 12 at both longitudinal ends is 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, and a wide cross-sectional area of the first member 11 and the second member 12 is ensured. Therefore, when a collision load is input from either end in the longitudinal direction of the cooling member 10, the first member 11 and the second member 12 can receive the collision load over a wide area. Accordingly, local deformation of the cooling member 10 is less likely to occur, and the battery cell 20 is more easily protected.

[0074] In the battery unit 100 according to the present embodiment, it is preferable that the first member 11 and the second member 12 of each cooling member 10 are formed of an aluminum-based plated steel sheet. It is preferable that an Al-based plating layer is provided over the entire surface of at least each of the first member 11 and the second member 12 on the space 13 side. Thereby, corrosion of the first member 11 and the second member 12 by the coolant is suppressed. By suppressing the 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 the 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 the present 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, it is preferable that a chemical conversion coating is formed on the surface of the zinc-based plated steel sheet. It is preferable that a Zn-based plating layer is provided over the entire surface of at least each of the first member 11 and the second member 12 on the space 13 side, and this Zn-based plating layer is covered with a chemical conversion coating. Thereby, corrosion of the first member 11 and the second member 12 by the coolant is more likely to be suppressed. Therefore, a decrease in the thermal conductivity of the first member 11 and the second member 12 and elution of the components of the first member 11 and the second member 12 into the coolant are less likely to occur.

[0076] In the battery unit 100 according to the present embodiment, it is preferable that the first member 11 and the second member 12 of each cooling member 10 have a Vickers hardness of 130 HV or more. Thereby, the cooling member 10 can exhibit higher impact resistance performance.

[0077] As described above, the embodiments according to the present disclosure have been described. However, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit thereof.

[0078] In the above-described embodiment, all the cooling members 10 included in the battery unit 100 extend in the same direction. However, it is not necessarily required that all 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, a plurality of battery cells 20 are arranged between adjacent cooling members 10 and adhered to the first member 11 or the second member 12 of at least one of the cooling members 10.

[0079] In the above-described embodiment, the top plate 111, the peripheral wall 112, and the flange 113 of the first member 11 have substantially symmetric shapes with 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 symmetric shapes in a cross-sectional view. The first member 11 and the second member 12 only need to be able 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-described 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 the battery cells 20 are arranged on both sides of the cooling member 10, from the viewpoint of cooling these battery cells 20 as uniformly as possible, it is preferable that the first member 11 and the second member 12 have symmetric cross-sectional shapes as in the above-described embodiment.

[0080] In the above-described embodiment, in each of the cooling members 10, the inlets 114, 124 for the coolant are formed at one end in the longitudinal direction, and the outlets 115, 125 are formed at the other end in the longitudinal direction. 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 appropriately changed according to, for example, the shape of the cooling member 10 and the positional relationship between the cooling member 10 and the battery cell 20.

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

Example

[0083] Hereinafter, the present disclosure will be described in more detail by way of examples. However, 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, for a battery unit including a plurality of cooling members 10, a plurality of square battery cells 20, and a plurality of mounting members 40, similar to the above-described embodiment, a pole-shaped collision object was collided from the longitudinal direction of the cooling member 10 to confirm the deformation of the cooling member 10. Further, as a comparative example, the same analysis was performed on a battery unit in which the square battery cells 20 were omitted. In each of the example and the comparative example, the tensile strength of each cooling member 10 was set to 590 MPa and the plate thickness was set to 1.0 mm, and the tensile strength of each mounting member 40 was set to 1.5 GPa and the plate thickness was set to 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 the comparative example are normalized by the maximum load of the example.

[0086] As shown in FIG. 8, in the comparative example, since the battery cell 20 does not exist and each cooling member 10 is not stiffened by the battery cell 20, the cooling member 10 is bent as a whole 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 of the battery unit at the time of collision is generally low.

[0087] On the other hand, as shown in FIG. 9, in the example, since the battery cell 20 is adhered to each cooling member 10 and each cooling member 10 is stiffened by the battery cell 20, the portion of the cooling member 10 corresponding to the battery cell 20 hardly deformed. Therefore, as shown in FIG. 10, in the example, the load of the battery unit at the time of collision is clearly higher than that in the comparative example. That is, the battery unit according to the example has improved collision resistance performance compared to the battery unit according to the comparative example.

[0088] As shown in FIG. 9, in the example, since the end portions of each cooling member 10 protrude outward in the longitudinal direction from the battery cell 20, the end portions of each cooling member 10 are deformed ahead of the battery cell 20 and absorb the collision energy.

[0089] According to this analysis, in addition to the end portions of each cooling member 10 being deformed ahead of the battery cell 20 and absorbing the collision energy, the battery cell 20 is adhered to each cooling member 10 and each cooling member 10 is stiffened by the battery cell 20, and the effect related to the collision resistance performance that the load of the battery unit at the time of collision is clearly increased was confirmed.

Description of Reference Numerals

[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, joined to the first member at their outer peripheral portions to form a space into which a 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; a plurality of battery cells each having a metal can as an exterior material; and the plurality of battery cells are disposed between the space of one of the cooling members and the space of another cooling member, and are each adhered to the first member or the second member in at least one of the one cooling member and the other cooling member. The first member includes a first top plate, a first flange forming an outer peripheral portion of the first member, and a first peripheral wall connecting the first top plate to the first flange over the entire circumference of the first top plate. The second member includes a second top plate, a second flange forming an outer peripheral portion of the second member, and a second peripheral wall connecting the second top plate to the second flange over the entire circumference of the second top plate.

2. The battery unit according to claim 1, wherein both longitudinal ends of each of the plurality of cooling members protrude outward with respect to the plurality of battery cells.

3. The battery unit according to claim 1, wherein in each of the plurality of cooling members, the areas of the cross-sections 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 areas of the cross-sections perpendicular to the longitudinal direction of the first member and the second member at the position of the space, respectively.

4. The battery unit according to claim 1, wherein in each of the plurality of cooling members, the inlet is formed at one longitudinal end of the cooling member, and the outlet is formed at the other longitudinal end.

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

6. The battery unit according to 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, the battery unit.

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