Battery pack

Abstract

To provide a battery pack capable of preventing the performance of a battery module from deteriorating even when the outside air is in a low-temperature environment.SOLUTION: An electric pack 1 includes: a lower current collector plate 4; and a plurality of battery modules 5 fixed to a case 2 via the lower current collector plate 4. An area of the lower current collector plate 4 in a lateral direction perpendicular to a stacking direction is smaller than an area of each of the battery modules 5 in the lateral direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 describes a bipolar battery in which a plurality of unit cells are stacked in a stacking direction. In this technology, current collector plates are arranged on the upper and lower surfaces of each of the plurality of unit cells in the stacking direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-28977 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when current collector plates are arranged inside the upper and lower surfaces of a battery pack case that houses a battery module made up of multiple unit cells, when the outside air is in a low-temperature environment, the cold air from the outside air transfers heat to the battery module through the current collector plates, degrading the performance of the battery module and leaving room for improvement.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a battery pack that can prevent the performance of the battery module from deteriorating even when the outside air is in a low-temperature environment. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objectives, the battery pack of the present disclosure is a battery pack in which multiple battery modules fixed to a case via current collector plates are stacked along a stacking direction, and the area of the current collector plates in a lateral direction perpendicular to the stacking direction is smaller than the area of the battery modules in the lateral direction. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to prevent the performance of the battery module from deteriorating even when the outside air is in a low temperature environment. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a battery pack according to an embodiment. [Figure 2] FIG. 2 is a plan view showing the relationship between the lower current collector plate and the battery module included in the battery pack according to the embodiment. [Figure 3] FIG. 3 is a diagram showing the relationship between temperature and time in the temperature distribution between battery modules in a battery pack according to one embodiment. [Figure 4] FIG. 4 is a diagram showing the temperature distribution in the battery module at a specified time of the battery pack according to one embodiment before and after improvement. [Figure 5] FIG. 5 is a cross-sectional view showing a schematic configuration of a battery pack according to a modified example of the embodiment. [Figure 6] FIG. 6 is a plan view showing the relationship between a lower current collector plate and a battery module 5 included in a battery pack according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Battery packs according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical. Furthermore, the drawings referred to in the following description merely show a schematic representation of the shape, size, and positional relationship to the extent that the contents of the present disclosure can be understood. In other words, the present disclosure is not limited to the shape, size, and positional relationship exemplified in each drawing.

[0010] [Electric pack configuration] Fig. 1 is a cross-sectional view showing a schematic configuration of a battery pack according to one embodiment. The battery pack 1 shown in Fig. 1 includes a bipolar nickel-metal hydride battery, and is mounted on a vehicle or the like.

[0011] The battery pack 1 includes a case 2, a current collector 4 (hereinafter simply referred to as the "lower current collector 4") provided on the bottom surface of the case 2 via an insulating member 3, and a plurality of battery modules 5 fixed to the case 2 via the lower current collector 4 and stacked along the stacking direction (Z direction). The battery pack 1 also includes, between adjacent battery modules 5, a cooler 6 through which a refrigerant for cooling the battery modules 5 flows or a current-carrying plate 7 that electrically connects adjacent battery modules 5, and a top current collector 8. Note that while FIG. 1 illustrates an example in which four battery modules 5 are stacked, the present invention is not limited to this and the number of battery modules 5 can be changed as appropriate.

[0012] In the battery pack 1 configured as described above, the lower current collector plate 4, the plurality of battery modules 5, the cooler 6, the current-carrying plate 7, and the upper current collector plate 8 are stacked and electrically connected to each other so as to allow current and heat transfer, as indicated by the solid arrow A2. Furthermore, in the battery pack 1, the lower current collector plate 4 conducts heat in solid form with the case 2 and other components exposed to the outside air via the insulating member 3, serving as both a current path and a heat dissipation path for the battery modules 5. Furthermore, as indicated by the open arrow A1, the plurality of battery modules 5 are stacked so that some of them do not contact each other. In FIG. 1, the open arrow A1 indicates the direction of heat transfer, and the solid arrow A2 indicates the direction of current conduction and the direction of heat transfer.

[0013] Here, the lower current collector plate 4 will be described in detail. FIG. 2 is a plan view showing the relationship between the lower current collector plate 4 and the battery modules 5. As shown in FIGS. 1 and 2, the area of the horizontal surface of the lower current collector plate 4 in the lateral direction (X direction and Y direction) perpendicular to the stacking direction (Z direction) of the battery modules 5 is smaller than the area of the horizontal surface of the battery modules 5 in the lateral direction (X direction and Y direction). Specifically, as shown in FIG. 2, the lower current collector plate 4 is formed small so that it is located only inside the battery modules 5 in the lateral direction perpendicular to the stacking direction (Z direction) of the battery modules 5. Furthermore, when high insulation requirements are required, the lower current collector plate 4 is formed using a material with high electrical resistance, such as aluminum or stainless steel. Note that when low insulation requirements are required, the lower current collector plate 4 may be formed using a material with low electrical resistance, such as copper.

[0014] Furthermore, the lower current collector plate 4 has a predetermined thickness in the stacking direction to enhance the heat insulating effect from the outside air of the case 2. This predetermined thickness is the thickness (height) of the space K1 between the insulating member 3 and the lower surface of the battery module 5, which is a thickness that prevents air from acting as a fluid, i.e., a thickness that does not result in heat transfer.

[0015] In the battery pack 1 configured in this manner, the area of the horizontal plane in the lateral direction of the lower current collector plate 4 is smaller than the area of the horizontal plane in the lateral direction of the battery module 5, which increases the amount of heat generated by the battery module 5. Furthermore, in the battery pack 1, the area of the horizontal plane in the lateral direction of the lower current collector plate 4, which is close to the outside air, is small, so by creating a portion (space K1) of the battery module 5 that is not in contact with the case 2, it is possible to suppress heat transfer from the outside air via the case 2 and keep the battery module 5 warm.

[0016] [Temperature distribution between battery modules] Next, the temperature distribution among the battery modules 5 in the battery pack 1 will be described. FIG. 3 is a diagram showing the relationship between temperature and time in the temperature distribution between the battery modules 5 in the battery pack 1. FIG. 4 is a diagram showing the temperature distribution in the battery modules 5 of the battery pack 1 at a specified time before and after improvement. In FIG. 3, the horizontal axis represents time [minutes], and the vertical axis represents temperature [°C]. Furthermore, in FIG. 3, the line L1 represents the change over time in the temperature distribution between the battery modules 5 in the battery pack 1 using the lower current collector plate 4, and the line L P_MAX indicates the time change of the maximum temperature distribution between the battery modules 5 in the conventional battery pack 1, and the line L P_MIN 4 shows the change over time in the minimum value of the temperature distribution between the battery modules 5 in the conventional battery pack 1. In FIG. 4, the higher the temperature of the battery module 5, the darker it is.

[0017] Line L1 and line L in Figure 3 P_MAX and the line L P_MIN As shown in FIG. 4, the temperature distribution in the battery module 5 is mitigated (FIG. 4(A) → FIG. 4(B)), so that heat generation in the battery module 5 can be suppressed and the battery module 5 can be kept warm.

[0018] According to the embodiment described above, the horizontal surface area of the lower current collector plate 4 in the lateral direction is smaller than the horizontal surface area of the battery module 5 in the lateral direction, so that the performance of the battery module 5 can be prevented from deteriorating even when the outside air is in a low temperature environment.

[0019] Furthermore, according to one embodiment, the lower current collector 4 is located only inside the battery module 5 in the horizontal direction perpendicular to the stacking direction, and therefore, by insulating the outer periphery of the battery module 5, it is possible to suppress a drop in the temperature of the battery module 5.

[0020] Furthermore, according to one embodiment, the lower current collector 4 is formed using a material with high electrical resistance, such as aluminum or stainless steel, and thus the electrical resistance is increased, and the amount of heat generated when current is applied is increased, thereby raising the temperature of the battery pack 1.

[0021] (Variation) Fig. 5 is a cross-sectional view showing a schematic configuration of a battery pack according to a modified example of the embodiment. Fig. 6 is a plan view showing the relationship between a lower current collector plate and a battery module 5 included in the battery pack according to a modified example of the embodiment.

[0022] The battery pack 1A shown in Figures 5 and 6 includes a lower current collector 4A instead of the above-described lower current collector 4. The lower current collector 4A has a rectangular cylindrical shape. This forms an internal space K2 between the lower current collector 4A and the battery module 5. The lower current collector 4A is made of a material with high electrical resistance, such as aluminum or stainless steel.

[0023] Furthermore, the lower current collector 4A has a predetermined thickness in the stacking direction of the battery modules 5 to enhance the heat insulating effect from the outside air of the case 2. This predetermined thickness is the thickness (height) of the space K2 between the insulating member 3 and the lower surface of the battery module 5, which is a thickness that prevents air from acting as a fluid, i.e., a thickness that does not result in heat transfer.

[0024] According to the modified example of the embodiment described above, the battery pack 1A can increase the amount of heat generated at the outer periphery of the battery module 5, thereby warming the area near the outer periphery of the battery module 5, which is prone to temperature drops, and suppressing the temperature drop near the outer periphery of the battery module 5.

[0025] In a modified example of one embodiment, the lower current collecting plate 4A is in the shape of a square tube, but is not limited to this and may be, for example, in a cylindrical or honeycomb structure, or in any shape that can form a space inside.

[0026] (Other forms) Further advantages and modifications will readily occur to those skilled in the art. The invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0027] Although some of the embodiments of the present application have been described in detail above with reference to the drawings, these are merely examples, and the present invention can be implemented in other forms that have undergone various modifications and improvements based on the knowledge of those skilled in the art, including the aspects described in the disclosure of the present invention. [Explanation of symbols]

[0028] 1.1A battery pack 2 cases 3. Insulating materials 4,4A bottom current collector plate 5 Battery Module 6 Cooler 7 Current-carrying board 8 Upper current collecting plate

Claims

1. A battery pack in which a plurality of battery modules are stacked in a stacking direction, the battery modules being fixed to a case via current collector plates, The current collecting plate is an area in a lateral direction perpendicular to the stacking direction is smaller than an area in the lateral direction of the battery module; Battery pack.

2. 2. The battery pack according to claim 1, The current collecting plate is located only inside the battery module in the lateral direction; Battery pack.

3. 2. The battery pack according to claim 1, The current collecting plate is It has a square cylindrical shape. Battery pack.

4. 2. The battery pack according to claim 1, The current collecting plate is It is made of aluminum or stainless steel. Battery pack.

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