Battery pack and method for manufacturing the battery pack

Abstract

To provide a battery pack which can suppress variation of a restraint pressure and include excellent cooling performance.SOLUTION: A battery pack contains: a first battery 10A; a second battery 10B; a cooling member 20 that is arranged to between the first and second batteries in a thickness direction; a binding member 30 that binds the first and second batteries, and the cooling member in the thickness direction. The cooling member includes a first surface; a first convex part 26a that surrounds an outer edge of the first surface and is projected to the first battery side from the first surface in the thickness direction; a second surface that is positioned to a side opposite to the first surface; and a second convex part 26b that surrounds the outer edge of the second surface, and is projected to the second battery side from the second surface in the thickness direction. In each of the first and second surfaces, a first heat conduction material layer 40A and a second heat conduction material layer 40B are arranged, and the first heat conduction material layer includes a first region having a height that is similar to that of the first convex part. The second heat conduction material layer includes a second region having the height that is similar to that of the second convex.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery pack and a method for manufacturing the battery pack. [Background technology]

[0002] Development of batteries such as lithium ion secondary batteries is actively underway. For example, Patent Document 1 discloses a bipolar battery having a bipolar electrode having a bipolar current collector foil, a positive electrode composite layer, and a negative electrode composite layer, and a unit cell having a positive electrode having a positive electrode current collector foil and a positive electrode composite layer, and a negative electrode having a negative electrode current collector foil and a negative electrode composite layer. Patent Document 2 discloses an electricity storage device including a plurality of storage cells stacked in a first direction and a thermally conductive material provided between the plurality of storage cells. Patent Document 3, although not a technology related to batteries, discloses a coating nozzle capable of coating a highly viscous coating material with a smooth coating appearance, a thin film, and an appropriate pattern width. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-195076 A [Patent Document 2] JP 2022-135610 A [Patent Document 3] JP 2014-155904 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a battery pack having a plurality of batteries, a cooling member may be disposed between two opposing batteries. In a battery pack having a plurality of batteries, for example, a confining pressure may be applied to the plurality of batteries in the thickness direction in order to prevent the batteries from shifting in a direction perpendicular to the thickness direction of the batteries. In order to suppress the variation in the confining pressure, it is assumed that a frame-shaped protrusion is provided on the cooling member. Although the variation in the confining pressure can be suppressed by providing the cooling member with a frame-shaped protrusion, a gap is generated between the cooling member and the batteries, and therefore the cooling of the batteries by the cooling member may be insufficient.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and has a primary object to provide a battery pack that can suppress variations in confining pressure and has good cooling performance. [Means for solving the problem]

[0006] [1] a first battery, a second battery, a cooling member arranged between the first battery and the second battery in a thickness direction, and a restraining member that restrains the first battery, the second battery, and the cooling member in the thickness direction, wherein the cooling member has a first surface, a first convex portion surrounding an outer edge of the first surface and protruding from the first surface toward the first battery in the thickness direction, a second surface located on the opposite side to the first surface, and a second convex portion surrounding an outer edge of the second surface and protruding from the second surface toward the second battery in the thickness direction, a first thermally conductive layer and a second thermally conductive layer are arranged on the first surface and the second surface, respectively, the first thermally conductive layer has a first region having the same height as the first convex portion, and the second thermally conductive layer has a second region having the same height as the second convex portion.

[0007] [2] The battery pack described in [1], wherein the first battery and the second battery are electrically connected via the cooling member, and the first convex portion and the second convex portion are conductive portions.

[0008] [3] The battery pack described in [1] or [2], wherein the cooling member has a first member having the first surface and the first convex portion, a second member having the second surface and the second convex portion, and a hollow member arranged between the first member and the second member in the thickness direction.

[0009] [4] A battery pack described in any of [1] to [3], wherein a first groove portion is arranged on the first surface of the cooling member, and a second groove portion is arranged on the second surface of the cooling member.

[0010] [5] A battery pack described in any of [1] to [4], wherein a ratio of an area of ​​the first thermal conductive layer to an area of ​​the first surface and a ratio of an area of ​​the second thermal conductive layer to an area of ​​the second surface are 65% or more and 100% or less, respectively.

[0011] [6] The battery pack according to any one of [1] to [5], wherein the first battery and the second battery each have at least one bipolar electrode.

[0012] [7] a first precursor layer forming step of forming a first precursor layer by applying a thermal conductive material to a first surface of the cooling member; a first thermal conductive material layer forming step of forming the first thermal conductive material layer from the first precursor layer by arranging the first battery on the first convex portion of the cooling member after the first precursor layer forming step; a second precursor layer forming step of forming a second precursor layer by applying a thermal conductive material to the second surface of the cooling member; and a second thermal conductive material layer forming step of forming the second thermal conductive material layer from the second precursor layer by arranging the second battery on the second convex portion of the cooling member after the second precursor layer forming step, wherein the first precursor layer and the second precursor layer each have a convex cross-sectional shape when viewed in the thickness direction.

[0013] [8] The method for manufacturing a battery pack described in [7], wherein the convex shape has an arc-shaped surface.

[0014] [9] The method for manufacturing a battery pack described in [7] or [8], wherein the first precursor layer has a first protruding region protruding further than the first convex portion in the thickness direction, and the second precursor layer has a second protruding region protruding further than the second convex portion in the thickness direction. Effect of the Invention

[0015] The present disclosure has an effect of providing a battery pack that can suppress variations in confining pressure and has good cooling performance. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view illustrating a battery pack according to the present disclosure. [Diagram 2] 1A and 1B are schematic cross-sectional and plan views illustrating a cooling member and a thermally conductive material layer in the present disclosure. [Diagram 3] 1 is a schematic cross-sectional view illustrating an electrode according to the present disclosure. [Figure 4] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. [Diagram 5] 2 is a schematic cross-sectional view illustrating a cooling member according to the present disclosure. [Figure 6] 1A and 1B are a schematic plan view and a schematic cross-sectional view illustrating a cooling member in the present disclosure. [Figure 7] 1 is a schematic cross-sectional view illustrating a battery and a cooling member according to the present disclosure. [Figure 8] 1 is a schematic cross-sectional view illustrating a battery pack according to the present disclosure. [Figure 9] FIG. 2 is a flow diagram illustrating a method for manufacturing a battery pack in the present disclosure. [Figure 10] 1 is a schematic cross-sectional view illustrating a mechanism by which air bubbles remain. [Figure 11] 1 is a schematic cross-sectional view illustrating a mechanism by which residual air bubbles are suppressed. FIG. [Figure 12] 3A to 3C are schematic cross-sectional views illustrating a battery preparation process in the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Each of the drawings shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, in this specification, when expressing an aspect in which another member is arranged relative to a certain member, the term "above" or "below" is used, unless otherwise specified, it includes both a case in which another member is arranged directly above or below a certain member so as to be in contact with the certain member, and a case in which another member is arranged above or below a certain member via another member.

[0018] A. Battery pack Fig. 1 is a schematic cross-sectional view illustrating a battery pack according to the present disclosure. As shown in Fig. 1, the battery pack 100 includes a first battery 10A, a second battery 10B, a cooling member 20 disposed between the first battery 10A and the second battery 10B in the thickness direction z, and a restraining member 30 that restrains the first battery 10A, the second battery 10B, and the cooling member 20 in the thickness direction z.

[0019] FIG. 2(a) is a schematic cross-sectional view illustrating a cooling member in the present disclosure, and FIG. 2(b) is a schematic plan view illustrating a cooling member in the present disclosure. FIG. 2(a) corresponds to an AA cross-sectional view of FIG. 2(b). For convenience, the first battery and the second battery are omitted in FIG. 2(a) and FIG. 2(b). As shown in FIG. 2(a) and FIG. 2(b), the cooling member 20 has a first surface 25a, a first protrusion 26a surrounding an outer edge O1 of the first surface 25a and protruding toward the first battery side (upper side in FIG. 2(a)) from the first surface 25a in the thickness direction z, a second surface 25b located on the opposite side to the first surface 25a, and a second protrusion 26b surrounding an outer edge (not shown) of the second surface 25b and protruding toward the second battery side (lower side in FIG. 2(a)) from the second surface 25b in the thickness direction z.

[0020] 2(a), a first thermally conductive layer 40A and a second thermally conductive layer 40B are disposed on the first surface 25a and the second surface 25b, respectively. The first thermally conductive layer 40A has a first region 45A having the same height as the first protrusion 26a, and the second thermally conductive layer 40B has a second region 45B having the same height as the second protrusion 26b.

[0021] According to the present disclosure, since the cooling member has a first convex portion and a second convex portion, and a first thermally conductive material layer and a second thermally conductive material layer are arranged on the first surface and the second surface of the cooling member, respectively, it is possible to suppress variations in the confining pressure and to obtain a battery pack with good cooling performance.

[0022] As described above, in a battery pack having multiple batteries, a cooling member may be disposed between two opposing batteries. By disposing the cooling member, it is possible to suppress deterioration of the batteries over time due to heat generated by the battery reaction. In addition, in a battery pack having multiple batteries, a confining pressure may be applied to the multiple batteries in the thickness direction in order to prevent the batteries from shifting in a direction perpendicular to the thickness direction of the batteries, for example.

[0023] When the confining pressure is applied, for example, due to the bending of the battery, the actually applied confining pressure may vary. In particular, in large batteries, bending is likely to occur, and the variation in the confining pressure becomes significant. In order to suppress the variation in the confining pressure, it is assumed that a frame-shaped protrusion is provided on the cooling member. Although the variation in the confining pressure can be suppressed by providing a frame-shaped protrusion on the cooling member, a gap is generated between the cooling member and the battery, and therefore the cooling of the battery by the cooling member may be insufficient.

[0024] In contrast, in the present disclosure, the cooling member has a first convex portion and a second convex portion, so that the variation in the confining pressure can be suppressed. Furthermore, the first and second thermally conductive layers are disposed on the first and second surfaces of the cooling member, respectively, so that the cooling member efficiently cools the battery.

[0025] 1.Battery The battery pack in the present disclosure includes at least a first battery and a second battery. In the present disclosure, the battery arranged on one surface side of the cooling member is defined as the first battery, and the battery arranged on the other surface side is defined as the second battery.

[0026] The battery in the present disclosure usually includes an electrode. The electrode has a current collector and an electrode layer (positive electrode active material layer or negative electrode active material layer) disposed on at least one surface of the current collector. FIG. 3 is a schematic cross-sectional view illustrating an electrode in the present disclosure. As shown in FIG. 3, the electrode E is, for example, a bipolar electrode BP having a current collector 1, a positive electrode active material layer 2 disposed on one surface of the current collector 1, and a negative electrode active material layer 3 disposed on the other surface of the current collector 1 in the thickness direction z.

[0027] 4 is a schematic cross-sectional view illustrating a battery according to the present disclosure. As shown in FIG. 4, the battery 10 preferably includes a plurality of electrodes E stacked in the thickness direction z. The battery 10 shown in FIG. 4 includes a bipolar electrode BP 1 , bipolar electrode BP 2 , a positive end electrode CA, and a negative end electrode AN. 1 and bipolar electrode BP 2 Each of the electrodes has a current collector 1, a positive electrode active material layer 2 arranged on one surface of the current collector 1, and a negative electrode active material layer 3 arranged on the other surface of the current collector 1. The positive electrode end electrode CA has a current collector 1 and a positive electrode active material layer 2 arranged on one surface of the current collector 1. The negative electrode end electrode AN has a current collector 1 and a negative electrode active material layer 3 arranged on one surface of the current collector 1. The battery in the present disclosure does not have to have a bipolar electrode.

[0028] As shown in FIG. 4, the battery 10 typically has a power generation unit U (U 1 ~U 3 ). The power generation unit U has a positive electrode active material layer 2, a negative electrode active material layer 3, and a separator (electrolyte layer) 4 arranged between the positive electrode active material layer 2 and the negative electrode active material layer 3. The power generation unit U shown in FIG. 4 is sealed with a seal member 5 and a cover member 6, and the inside of the power generation unit U is filled with an electrolyte 7. As a result, the positive electrode active material layer 2, the negative electrode active material layer 3, and the separator 4 are each impregnated with the electrolyte. The battery according to the present disclosure may have one power generation unit, or may have two or more power generation units.

[0029] The battery 10 shown in FIG. 4 is made up of a plurality of power generating units (U 1 , U 2 , U 3 ) As shown in FIG. 4, the plurality of power generating units may be directly connected to each other. Although not shown in the figure, the plurality of power generating units may be connected in parallel to each other. The plurality of power generating units are independent of each other so that the electrolyte does not flow between them. In FIG. 4, the plurality of power generating units U 1 ~U 3 are independent of each other so that the electrolyte does not flow between them. For example, 1 and unit of electricity generation U 2 are partitioned by a current collector 1 and a sealing member 5 and are independent from each other. As shown in Fig. 4, a battery 10 preferably has a plurality of electrodes E stacked in a thickness direction z and a sealing member 5 disposed along the outer edges of the plurality of electrodes E as viewed from the thickness direction z.

[0030] The planar shape of the battery (shape seen from the thickness direction) can be, for example, a quadrangle such as a square or a rectangle. The length of each side constituting the planar shape of the battery is, for example, 30 cm or more, or may be 60 cm or more, or may be 1 m or more. On the other hand, the length of each side is, for example, 3 m or less.

[0031] As described above, in this disclosure, the battery arranged on one surface side of the cooling member is defined as the first battery, and the battery arranged on the other surface side is defined as the second battery. The number of electrodes in the first battery and the second battery may be the same or different. Similarly, the number of power generation units in the first battery and the second battery may be the same or different.

[0032] 2. Cooling material The cooling member in the present disclosure is disposed between the first battery and the second battery in the thickness direction.

[0033] 2(a) and 2(b), the cooling member 20 has a first surface 25a, a first protrusion 26a surrounding an outer edge O1 of the first surface 25a and protruding from the first surface 25a toward the first battery side (upper side in FIG. 2(a)) in the thickness direction z, a second surface 25b located on the opposite side to the first surface 25a, and a second protrusion surrounding an outer edge (not shown) of the second surface 25b and protruding from the second surface 25b toward the second battery side (lower side in FIG. 2(a)) in the thickness direction z. Also, as shown in FIG. 2(a), the cooling member 20 preferably has a flow path H for circulating a refrigerant.

[0034] As shown in FIG. 2(a), the first surface 25a is a surface having the thickness direction z as a normal direction. On the other hand, as shown in FIG. 2(b), the first protrusion 26a is arranged so as to surround the outer edge O1 of the first surface 25a. Although not particularly shown, the first protrusion may be arranged so as to surround 50% or more of the entire circumference of the outer edge of the first surface, may be arranged so as to surround 70% or more, or may be arranged so as to surround 90% or more. The first protrusion may be arranged so as to surround the entire circumference of the outer edge of the first surface. That is, the first protrusion 26a may be arranged in a frame shape with respect to the first surface. As shown in FIG. 2(a), the first protrusion 26a protrudes from the first surface 26a toward the first battery (upper side in FIG. 2(a)) in the thickness direction z. It is preferable that the first protrusion 26a is capable of surface contact with the first battery (not shown). This is because when the first protrusion 26a is used as a conductive portion, the resistance can be reduced.

[0035] As shown in FIG. 2(a), the second surface 25b is a surface located on the opposite side to the first surface 25a, and has a normal direction in the thickness direction z. Although not shown in particular, the second convex portion is disposed so as to surround the outer edge of the second surface. As shown in FIG. 2(a), the second convex portion 26b protrudes toward the second battery side (the lower side in FIG. 2(a)) from the second surface 25b in the thickness direction z. The details of the second convex portion are the same as those of the first convex portion described above, and the above description can be appropriately cited by replacing "first" with "second."

[0036] The cooling member in the present disclosure may be a single member or may be a member composed of multiple members. FIG. 5(a), FIG. 5(b), and FIG. 5(c) are schematic cross-sectional views illustrating the cooling member in the present disclosure. Note that FIG. 5(b) and FIG. 5(c) are exploded views. For example, as shown in FIG. 5(a), the cooling member 20 may be a single member. On the other hand, as shown in FIG. 5(b), the cooling member 20 may be a member composed of a first member 21 having a first surface 25a and a first convex portion 26a, and a second member 22 having a second surface 25b and a second convex portion 26b. In the cooling member 20 shown in FIG. 5(b), a flow path H is formed by the flat surface of the first member 21 and the uneven surface of the second member 22.

[0037] 5(c), the cooling member 20 may be a member composed of a first member 21 having a first surface 25a and a first convex portion 26a, a second member 22 having a second surface 25b and a second convex portion 26b, and a hollow member 23 disposed in the thickness direction between the first member 21 and the second member 22. The hollow member 23 has a flow path H as a hollow portion for circulating the refrigerant.

[0038] FIG. 6(a) is a schematic plan view illustrating the cooling member in the present disclosure, and FIG. 6(b) is a cross-sectional view taken along line AA of FIG. 6(a). As shown in FIG. 6(a) and FIG. 6(b), a first groove 27a may be disposed on a first surface 25a of the cooling member 20. For example, by disposing a temperature sensor such as a thermocouple in the first groove, the temperature of the battery pack can be more accurately monitored and managed. Although not shown, a second groove may be disposed on a second surface of the cooling member. The details of the second groove are the same as those of the first groove described above, and the above description may be appropriately cited with "first" replaced with "second".

[0039] In the present disclosure, the first battery and the second battery may be electrically connected via a cooling member. In this case, the first battery and the second battery may be connected in series or in parallel. In addition, when the first battery and the second battery are electrically connected via a cooling member, it is preferable that the first convex portion and the second convex portion are conductive portions. That is, it is preferable that the first battery and the second battery are electrically connected via at least the first convex portion and the second convex portion.

[0040] 7, the first protrusion 26a of the cooling member 20 is preferably disposed at a position overlapping with the sealing member 5 of the first battery 10A when viewed from the thickness direction z. Similarly, the first protrusion 26a of the cooling member 20 is preferably disposed at a position overlapping with the electrode E of the first battery 10A when viewed from the thickness direction z. Furthermore, the first surface 25a of the cooling member 20 is preferably disposed inside the outer edge of the electrode E of the first battery 10A when viewed from the thickness direction z.

[0041] 7, the second convex portion 26b of the cooling member 20 is preferably disposed at a position overlapping with the sealing member 5 of the second battery 10B when viewed from the thickness direction z. Similarly, the second convex portion 26b of the cooling member 20 is preferably disposed at a position overlapping with the electrode E of the second battery 10B when viewed from the thickness direction z. Furthermore, the second surface 25b of the cooling member 20 is preferably disposed inside the outer edge of the electrode E of the second battery 10B when viewed from the thickness direction z.

[0042] As shown in FIG. 2(a), the height of the portion of the first protrusion 26a protruding from the first surface 25a in the thickness direction z is H a The height of the second protrusion 26b protruding from the second surface 25b is H b Let us assume that. a and H b can be adjusted according to the size of the battery. a and H bare, for example, 0.70 mm or more, may be 1.00 mm or more, may be 1.20 mm or more, or may be 1.40 mm or more. a and H b are, for example, 2.20 mm or less, may be 2.00 mm or less, may be 1.80 mm or less, or may be 1.60 mm or less.

[0043] The material of the cooling member in the present disclosure is not particularly limited, but examples thereof include metals such as aluminum, copper, iron, and SUS.

[0044] 3. Thermally conductive layer The battery pack of the present disclosure has, as the thermally conductive material layers, a first thermally conductive material layer disposed on a first surface of the cooling member and a second thermally conductive material layer disposed on a second surface of the cooling member. The first thermally conductive material layer has a first region having the same height as the first protrusion, and the second thermally conductive material layer has a second region having the same height as the second protrusion. In the first region, the first thermally conductive material layer is usually in contact with both the first surface of the cooling member and the first battery. Similarly, in the second region, the second thermally conductive material layer is usually in contact with both the second surface of the cooling member and the second battery.

[0045] The first and second thermally conductive layers usually contain a thermally conductive material. The thermal resistance of the thermally conductive material is, for example, 0.2 K / W or less. The volume resistivity of the thermally conductive material is, for example, 1×10 10 The thermal conductivity is Ω·cm or more. The breakdown voltage of the thermal conductive material is, for example, 5 kV or more. As the thermal conductive material, for example, a heat dissipating grease that can be cured at room temperature (for example, the CGW (registered trademark) series manufactured by Sekisui Polymatech Co., Ltd.) can be used.

[0046] As shown in FIG. 2A, the first thermally conductive layer 40A has a height H aThe first region 45A has a height equal to that of the first surface. The ratio of the area of ​​the first region 45A to the area of ​​the first thermally conductive material layer 40A may be 100% or less. In the latter case, the ratio is, for example, 50% or more, 70% or more, 90% or more, or 95% or more. The ratio of the area of ​​the first thermally conductive material layer to the area of ​​the first surface is, for example, 65% or more, 70% or more, 75% or more, or 80% or more. On the other hand, the ratio is, for example, 100% or less, 95% or less, 90% or less, or 85% or less.

[0047] As shown in FIG. 2(a), the second thermally conductive layer 40B has a height H b The ratio of the area of ​​the second region 45B to the area of ​​the second thermally conductive material layer 40B may be 100% or less than 100. In the latter case, the ratio is, for example, 50% or more, 70% or more, 90% or more, or 95% or more. The ratio of the area of ​​the second thermally conductive material layer to the area of ​​the second surface is, for example, 65% or more, 70% or more, 75% or more, or 80% or more. On the other hand, the ratio is, for example, 100% or less, 95% or less, 90% or less, or 85% or less.

[0048] 4. Restraint member The restraining member in the present disclosure is a member that restrains the first battery, the second battery, and the cooling member in the thickness direction.

[0049] The restraining member in the present disclosure is not particularly limited as long as it is a member capable of restraining the first battery, the second battery, and the cooling member in the thickness direction, and any known restraining member can be used. For example, the restraining member 30 shown in FIG. 1 has a pair of end plates 31, a connecting member 32 that connects the pair of end plates 31, and a fixing member 33 that fixes the end plates 31 and the connecting member 32.

[0050] 5. Battery pack The battery pack in the present disclosure has two or more batteries. In the present disclosure, the battery pack may have three or more batteries, or may have four or more batteries.

[0051] As described above, in the present disclosure, the battery arranged on one surface side is defined as the first battery, and the battery arranged on the other surface side is defined as the second battery, with the cooling member as the reference. FIG. 8 is a schematic cross-sectional view illustrating a battery pack in the present disclosure. For convenience, the illustration of the restraining member is omitted. The battery pack 100 shown in FIG. 8 has four batteries 10 (10p, 10q, 10r, 10s). With the cooling member 20x as the reference, the battery 10p arranged on one surface side corresponds to the first battery, and the battery 10q arranged on the other surface side corresponds to the second battery. With the cooling member 20y as the reference, the battery 10r arranged on one surface side corresponds to the first battery, and the battery 10s arranged on the other surface side corresponds to the second battery.

[0052] 8, an adhesive layer 60 may be disposed between adjacent batteries (battery 10q and battery 10r) in the thickness direction z. By disposing the adhesive layer 60, it is possible to suppress misalignment in a direction perpendicular to the thickness direction z (the left-right direction on the paper).

[0053] The battery pack in the present disclosure is typically a lithium-ion secondary battery. Examples of uses of the battery pack include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, the battery pack is preferably used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery pack in the present disclosure may also be used as a power source for moving objects other than vehicles (e.g., railways, ships, and aircraft), and may also be used as a power source for electrical appliances such as information processing devices.

[0054] B. Battery Pack Manufacturing Method The manufacturing method of the battery pack in the present disclosure is the manufacturing method of the battery pack described above. Also, as shown in Fig. 9, the manufacturing method of the battery pack in the present disclosure includes a battery preparation step, a cooling member preparation step, a first precursor layer forming step, a first thermal conductive material layer forming step, a second precursor layer forming step, and a second thermal conductive material layer forming step. The present disclosure is characterized in that a predetermined cooling member is used, a predetermined thermal conductive material layer is formed, and the cross-sectional shape of the precursor layer has a convex shape.

[0055] According to the present disclosure, by using a cooling member having a first convex portion and a second convex portion and further forming a thermally conductive material layer between the cooling member and the battery, it is possible to obtain good cooling performance while suppressing variations in the confining pressure. In addition, since the cross-sectional shape of the precursor layer has a convex shape, it is possible to suppress the remaining of air bubbles.

[0056] Here, the remaining of air bubbles will be explained with reference to FIG. 10 and FIG. 11. As shown in FIG. 10(a), when the precursor layer 41 is formed on the surface of the cooling member 20 by using, for example, a printing method, minute irregularities are formed on the surface of the precursor layer 41 on the side of the battery 10. In particular, when a thermally conductive material with high viscosity is used, minute irregularities are easily formed. As shown in FIG. 10(b), when the battery 10 and the cooling member 20 are pressurized in a state in which minute irregularities are formed, the minute irregularities remain on the surface of the precursor layer 41 on the side of the battery 10 without disappearing. As a result, as shown in FIG. 11(c), a thermally conductive material layer 40 in which air bubbles V remain is formed. The air bubbles V function as a heat insulating layer and inhibit the cooling of the battery 10 by the cooling member 20.

[0057] In contrast, in the manufacturing method of the battery pack according to the present disclosure, as shown in FIG. 11(a), in the precursor layer forming step, a precursor layer 41 having a convex cross-sectional shape is formed. A convex shape refers to a shape in which the center protrudes more than both ends. Since the precursor layer 41 has a convex cross-sectional shape, as shown in FIG. 11(b), when the precursor layer 41 is pressed in the thickness direction z, the precursor layer 41 is deformed so as to expand in a direction perpendicular to the thickness direction (left-right direction on the paper). During this deformation, air is pushed out. As a result, as shown in FIG. 11(c), a thermally conductive material layer 40 in which residual air bubbles are suppressed is formed.

[0058] 1.Battery preparation process The battery preparation step in the present disclosure is a step of preparing the first battery and the second battery. The first battery and the second battery are the same as those described in "A. Battery pack", so the description here is omitted.

[0059] 12A to 12C are schematic cross-sectional views illustrating a battery preparation process. First, as shown in FIG. 12A, a bipolar electrode BP 1 and bipolar electrode BP 2 Prepare the bipolar electrode BP. 1 and bipolar electrode BP 2 Each of the bipolar electrodes BP has frame members 5a and 5b for forming a seal member, which are arranged along the outer edge of the current collector 1. 1 The negative electrode active material layer 3 and the bipolar electrode BP 2 The positive electrode active material layer 2 in the positive electrode 1 faces the positive electrode active material layer 2 in the positive electrode 1 with the separator 4 interposed therebetween. At this time, at least a part of the outer edge of the separator 4 is disposed between the frame member 5a and the frame member 5b. Also, as shown in FIG. 12(a), the bipolar electrode BP 1 The frame member 5a and the bipolar electrode BP 2A nest α and a frame member (spacer) 5c are placed between the frame member 5b in the stacked state. Next, although not shown, a positive end electrode CA and a negative end electrode AN are also stacked. After that, the stacked frame members are welded together to form a seal member 5. In this way, a stacked member as shown in FIG. 12(b) is obtained. Next, as shown in FIG. 12(c), the nest α is removed from the stacked member to form a through hole β penetrating the seal member 5. Next, although not shown, an electrolyte is injected from the through hole, and the through hole is sealed with a resin after the electrolyte is injected. In this way, a battery 10 as shown in FIG. 4 is obtained.

[0060] 2. Cooling material preparation process The cooling member preparation step in the present disclosure is a step of preparing the cooling member. The cooling member is the same as that described in "A. Battery pack", so the description thereof will be omitted here.

[0061] 3. First precursor layer formation process The first precursor layer forming step in the present disclosure is a step of applying a thermally conductive material to the first surface of the cooling member to form a first precursor layer. The thermally conductive material is the same as that described in "A. Battery pack", so the description here is omitted.

[0062] The method of applying the thermally conductive material is not particularly limited, but may be, for example, a method of applying the thermally conductive material in a line or dot shape using a nozzle. When applying the thermally conductive material in a line or dot shape, the thermally conductive material may be applied in one line or two or more lines along the first direction. Note that, when the first groove portion described above is disposed on the first surface, it is preferable not to apply the thermally conductive material to the first groove portion.

[0063] The cross-sectional shape of the first precursor layer viewed in the thickness direction is usually convex. For example, when the first precursor layer is linear when viewed in the thickness direction, the cross-sectional shape of the first precursor layer cut in the thickness direction along a direction perpendicular to the extension direction is preferably convex. Specifically, as shown in FIG. 11(a), the precursor layer 41 preferably has an arc-shaped surface S1.

[0064] The first precursor layer preferably has a first projecting region that projects further than the first protruding portion in the thickness direction. The ratio of the first projecting region to the height of the first protruding portion is, for example, 1.01 or more and 1.30 or less. Also, the ratio of the first projecting region to the area of ​​the first precursor layer in the thickness direction is usually less than 100%. On the other hand, the ratio is, for example, 50% or more, and may be 70% or more.

[0065] 4. First thermal conductive material layer formation process The first thermally conductive material layer forming step in the present disclosure is a step of forming the first thermally conductive material layer from the first precursor layer by disposing the first battery on the first protruding portion of the cooling member after the first precursor layer forming step. Specifically, the first precursor layer is pressurized by the first battery to form the first thermally conductive material layer. In addition, the first region is formed by pressing the first precursor layer by the first battery.

[0066] In the first thermally conductive material layer forming step, it is preferable to place the first battery on the upper side in the direction of gravity with respect to the first convex portion of the cooling member, and to place the first battery on the first convex portion of the cooling member. When placing the first battery on the first convex portion of the cooling member, the first precursor layer may be pressurized by the weight of the first battery, or the first precursor layer may be pressurized by using a pressurizing device to pressurize the first battery and the cooling member, but the latter is preferable. This is because it is possible to further suppress the remaining of air bubbles. Details of the first thermally conductive material layer are the same as those described in "A. Battery pack" above.

[0067] 5. Second precursor layer formation process The second precursor layer forming step in the present disclosure is a step of applying a thermally conductive material to the second surface of the cooling member to form a second precursor layer. Details of the second precursor layer forming step are the same as those described in the first precursor layer forming step above, and the above description can be appropriately cited by replacing "first" with "second."

[0068] 6. Second thermal conductive material layer formation process The second thermal conductive layer forming step in the present disclosure is a step of forming the second thermal conductive layer from the second precursor layer by disposing the second battery on the second convex portion of the cooling member after the second precursor layer forming step. Details of the second thermal conductive layer forming step are the same as those of the first thermal conductive layer forming step described above, and the above description can be appropriately cited by replacing "first" with "second".

[0069] 7.Restraint process In the manufacturing method of the battery pack of the present disclosure, for example, after the first thermal conductive material layer forming step and the second thermal conductive material layer forming step, a restraining step may be included in which the first battery, the second battery, and the cooling member are restrained in the thickness direction using a restraining member. The restraining member is the same as that described in "A. Battery pack", so the description thereof is omitted.

[0070] 8. Battery pack The battery pack manufactured by the above-mentioned method is similar to that described in "A. Battery pack," so a description thereof will be omitted here.

[0071] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure. [Explanation of symbols]

[0072] 1...Current collector 2...Cathode active material layer 3...Negative electrode active material layer 4…Separator E…Electrode BP…Bipolar electrode U…Power generation unit 10A…1st battery 10B…Second battery 20...Cooling member 21…First member 22...Second member 23...Hollow member 30...Restraining member 40…Thermal conductive layer 100…Battery pack

Claims

1. A battery pack including a first battery, a second battery, a cooling member disposed between the first battery and the second battery in a thickness direction, and a restraining member that restrains the first battery, the second battery, and the cooling member in the thickness direction, the cooling member has a first surface, a first convex portion surrounding an outer edge of the first surface and protruding from the first surface toward the first battery in the thickness direction, a second surface located on the opposite side to the first surface, and a second convex portion surrounding an outer edge of the second surface and protruding from the second surface toward the second battery in the thickness direction, a first thermally conductive layer and a second thermally conductive layer are disposed on the first surface and the second surface, respectively; the first thermally conductive layer has a first region having the same height as the first protrusion; The second thermally conductive material layer has a second region having the same height as the second protrusion.

2. The battery pack according to claim 1 , wherein the first battery and the second battery are electrically connected via the cooling member, and the first convex portion and the second convex portion are current-carrying portions.

3. The cooling member is a first member having the first surface and the first protrusion; a second member having the second surface and the second protrusion; The battery pack according to claim 1 , further comprising: a hollow member disposed between the first member and the second member in the thickness direction.

4. a first groove portion is disposed on the first surface of the cooling member; The battery pack according to claim 1 , wherein a second groove portion is disposed on the second surface of the cooling member.

5. 2. The battery pack of claim 1, wherein a ratio of an area of ​​the first thermal conductive layer to an area of ​​the first surface and a ratio of an area of ​​the second thermal conductive layer to an area of ​​the second surface are 65% or more and 100% or less, respectively.

6. 2. The battery pack of claim 1, wherein the first battery and the second battery each have at least one bipolar electrode.

7. A method for manufacturing a battery pack according to any one of claims 1 to 6, comprising the steps of: a battery preparation step of preparing the first battery and the second battery; a cooling member preparation step of preparing the cooling member; a first precursor layer forming step of applying a thermally conductive material to the first surface of the cooling member to form a first precursor layer; a first thermal conductive material layer forming step of forming the first thermal conductive material layer from the first precursor layer by arranging the first battery on the first convex portion of the cooling member after the first precursor layer forming step; a second precursor layer forming step of applying a thermally conductive material to the second surface of the cooling member to form a second precursor layer; a second thermal conductive material layer forming step of forming the second thermal conductive material layer from the second precursor layer by arranging the second battery on the second convex portion of the cooling member after the second precursor layer forming step; having The method for manufacturing a battery pack, wherein the first precursor layer and the second precursor layer each have a cross-sectional shape when viewed in the thickness direction, the cross-sectional shape being a convex shape.

8. The method for manufacturing a battery pack according to claim 7 , wherein the convex shape has an arc-shaped surface.

9. the first precursor layer has a first projecting region that projects further than the first protruding portion in the thickness direction, The method for manufacturing a battery pack according to claim 7 , wherein the second precursor layer has a second projecting region that projects further than the second convex portion in the thickness direction.

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