Battery pack

Abstract

A battery pack is provided that reduces the temperature of cells in a battery group by reducing the thermal resistance of the battery group. [Solution] The battery pack described in the present invention has battery cells each having a pair of wide side surfaces, a pair of narrow side surfaces, a bottom surface connecting the wide side surfaces and the narrow side surfaces, and a top surface on which external terminals are arranged; the battery pack comprises a first group of batteries formed by stacking multiple cells with their wide side surfaces facing each other, a second group of batteries formed by stacking multiple cells with their wide side surfaces facing each other, and a housing for housing the first group of batteries and the second group of batteries; the wide side surfaces forming the top and bottom of the first group of batteries and the second group of batteries are arranged within the housing in positions that do not face each other; the surface on which the external terminals of the first group of batteries are arranged and the surface on which the external terminals of the second group of batteries are arranged are arranged opposite each other; and the surfaces opposite the terminals of the first group of batteries and the second group of batteries face the inner surface of the housing and do not face the other battery groups.

Description

[Technical field]

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

[0002] In the context of environmental and resource depletion issues, there is a demand for the development of energy-saving products with low environmental impact to protect the global environment. Eco-cars, such as hybrid electric vehicles and electric vehicles, are attracting attention as one of the products that can reduce CO2 emissions, and their sales numbers are increasing. Demand for secondary batteries to be installed in these eco-cars is also increasing. Examples of secondary batteries for automobiles include lithium-ion secondary batteries, lead-acid batteries, and nickel-metal hydride batteries. Among these, lithium-ion secondary batteries are generally considered promising because they have a higher discharge potential than lead batteries and nickel-metal hydride batteries, making them smaller and more energy dense.

[0003] For full-scale application, lithium-ion secondary batteries are required to have higher energy density, higher power density, and longer life. In order to increase the power output of a battery, it is effective to input and output a large current from the battery as well as to increase the potential. However, when a large current is input and output from a battery, heat is generated inside the battery due to the internal resistance of the battery. If the generated heat cannot be sufficiently removed from the battery, the battery temperature will rise. The battery characteristics of lithium-ion batteries, such as the battery capacity and internal resistance, tend to deteriorate depending on the battery temperature. In particular, the higher the battery temperature, the more the battery deteriorates, and in many cases, the capacity decreases and the internal resistance increases. Therefore, technology development to improve the heat dissipation performance of batteries is required.

[0004] When multiple lithium-ion cells (hereafter referred to as cells) are combined and used as a battery group (for example, when used as a battery module or battery pack), it is desirable to keep the temperature difference between the cells in the battery group small and to keep the maximum temperature reached by the batteries in the battery group low. This is because when the temperature difference between the cells is large and the maximum temperature reached is high, differences in deterioration are likely to occur between the cells. Since the characteristics of a battery group tend to be determined by the characteristics of the most deteriorated battery among the cells in the battery group, it is necessary to design a battery group that does not cause deterioration of specific batteries.

[0005] Therefore, various battery arrangement configurations have been developed for battery groups formed by combining a plurality of unit cells. For example, Patent Document 1 describes a configuration in which two battery groups, each consisting of five unit cells stacked in a direction approximately perpendicular to the wide surface of the unit cells, are arranged side by side on a plate that constitutes the bottom surface of a housing. In general, the same current value is applied to batteries connected in series, so that the temperature of the batteries will be approximately the same if the batteries have approximately the same internal resistance. In this case, it is known that the more the number of stacked batteries is, the closer the temperature of the center part of the stacked battery group becomes to an adiabatic state and the higher the temperature becomes compared to the end part of the battery group because it is difficult for heat flow to occur between the batteries. When the battery group connected in series is divided into two rows as in Patent Document 1, the battery group has the same configuration as five batteries stacked when viewed from the bottom surface of the housing, so there is an advantage that the temperature of the battery in the center part of the battery group is easily reduced. In addition, since the series battery group is divided, it is possible to reduce the height. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Pat. No. 9,406,916 Summary of the Invention [Problem to be solved by the invention]

[0007] When the side faces of the battery groups are thermally and physically connected to each other as in the structure described in Patent Document 1, the path for heat to escape from the connection surface of the battery groups must go through the member sandwiched between the battery groups and then dissipate through the housing in front of that member, which creates a problem of redundant heat dissipation paths.When the heat dissipation paths become redundant, the thermal resistance tends to increase, and there is room for improvement in order to improve heat dissipation.

[0008] In such a configuration, if the cooling efficiency decreases (for example, if the flow rate of forced air is small or if the input / output current is large and the heat generation of the unit cells is large), a distribution of battery temperature will occur within the configured battery group, and in particular, among the battery groups stacked in the battery group, the battery temperature of the unit cells located near the center will be high, and deterioration may progress. The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a battery pack in which the temperature difference between battery groups is small. [Means for solving the problem]

[0009] The battery pack described in the present invention has battery cells each having a pair of wide side surfaces, a pair of narrow side surfaces, a bottom surface connecting the wide side surfaces and the narrow side surfaces, and a top surface on which external terminals are arranged, and comprises a first battery group in which multiple battery cells are stacked with their wide side surfaces facing each other, a second battery group in which multiple battery cells are stacked with their wide side surfaces facing each other, and a housing for housing the first battery group and the second battery group, wherein the surface on which the external terminals of the first battery group are arranged and the surface on which the external terminals of the second battery group are arranged are arranged opposite each other. Effect of the Invention

[0010] According to the present invention, by arranging the surfaces on which the external terminals of the battery groups are arranged facing each other within the housing and creating a structure in which the battery groups are not thermally or physically connected to each other, it is possible to reduce the thermal resistance of the battery group and thereby reduce the temperature of the single cells within the battery group. [Brief description of the drawings]

[0011] [Figure 1]FIG. 1 is a diagram for explaining an example of a specific configuration of a battery group in Examples 1 and 2. [Diagram 2] FIG. 1 is a diagram for explaining an example of a specific wiring configuration implemented when the unit cells present in the opposing battery groups in Examples 1 and 2 are electrically connected in series. [Diagram 3] FIG. 1 is an exploded perspective view for explaining an example of a specific configuration of a battery module implemented when the battery groups in the first embodiment are arranged facing each other in a housing. [Figure 4] FIG. 4 is a plan view of the inside of the battery module shown in FIG. 3, with the lid removed, viewed from above the lid. [Diagram 5] FIG. 5 is an exploded plan view of the support base and the electrical equipment integrated in FIG. [Figure 6] FIG. 13 is a diagram for explaining an example of a specific configuration of a battery group in Example 3. [Figure 7] FIG. 13 is a diagram for explaining an example of a specific configuration of a battery group in Example 4. [Figure 8] FIG. 13 is a plan view of a specific example of a battery module configuration when the battery groups in the fifth embodiment are disposed facing each other in a housing, with the cover removed, as viewed from above. [Figure 9] FIG. 1 is a diagram for explaining an example of a specific configuration of a battery group in Comparative Example 1. [Figure 10] FIG. 1 is a diagram for explaining an example of a specific configuration of a battery group in Comparative Examples 2 and 3. [Figure 11] FIG. 1 is a graph comparing the temperature rise ratios of the battery groups in Example 1, Comparative Example 1, and Comparative Example 2. [Figure 12] FIG. 11 is a graph comparing the temperature rise ratio of the battery group in Example 2 and Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment for carrying out the present invention will be described. However, this embodiment is not limited to the following content at all, and can be modified as desired without departing from the gist of the present invention. The cooling environment in the present invention is an example, and can be applied to cases where a refrigerant other than air or water is used.

[0013] Although a lithium ion secondary battery is exemplified as the secondary battery in the present invention, the present configuration can be applied to other types of storage batteries. In addition, the effect can be obtained regardless of the constituent members of the lithium ion secondary battery. That is, in the present invention, an electrode made of an Al current collector foil and a positive electrode material having a layered structure is used as the positive electrode, and an electrode made of a Cu current collector foil and a carbon material is used as the negative electrode, but other configurations are also possible. For example, it is possible to improve heat dissipation even when an Al foil is used as the current collector foil of the negative electrode. In addition, a rectangular battery is used as the shape of the lithium ion battery in this embodiment, but the effect can be obtained even with batteries of other shapes known, such as a laminate type and a cylindrical type.

[0014] The number of battery groups contained in the housing may be any number as long as the side of the battery is in physical thermal contact with the side of the housing to shorten the heat dissipation path from the side of the battery group, as in the configuration of the present invention, but an even number is preferable to ensure the stability of the battery pack. For example, when there are two battery groups as in the embodiment of the present invention, the battery groups can be arranged on both the left and right side of the housing in physical thermal contact.

[0015] The number of cells constituting the battery group can be as defined in the present invention, and the effects of the present invention can be obtained regardless of the number of cells, as long as the cells can fit inside the housing and the desired voltage and capacity can be ensured. The fewer the number of stacked cells in one battery group, the greater the heat dissipation effect, but the number is preferably 100 or less, more preferably 20 or less, and most preferably 10 or less. By using six cells as in the present embodiment, a battery pack that is both compact and has good cooling properties can be obtained.

[0016] Furthermore, the effects of the present invention can be obtained even if the numbers of batteries in the opposing battery groups are not necessarily the same. For example, the effects of the present invention can be obtained even if the number of batteries in one of the battery groups is one or more more than the number of batteries in the other.

[0017] The effect of the present invention can be obtained even if, for example, an insulating sheet or a member with high thermal conductivity is disposed between the cells constituting the battery group, or the effect of the present invention can be obtained without such a configuration. The effect of the present invention can also be obtained by introducing a three-dimensional structure, such as a protrusion or groove of various shapes, such as a rail shape or a dot shape, into the insulating sheet or member with high thermal conductivity. When the side surface of the cell is covered with an insulating material, the material of these members can be a material with high thermal conductivity, such as aluminum, aluminum die-cast, copper, or iron. When the side surface of the cell is not covered with an insulating material, polypropylene, polyamide, polyetherimide, PPS, PPA, PBT, or a highly thermally conductive resin can be used.

[0018] In the present invention, since the battery groups are disposed facing each other inside the housing with their electrode surfaces facing each other, it is preferable to at least partially dispose an insulating member between the opposing battery groups in order to ensure crush safety. Examples of such members include the following.

[0019] The support base is made by using an insulating material as at least a part of its constituent members, and the support base may be provided with at least one of electrical components such as a battery safety mechanism (e.g., fuses, etc.), a control device (e.g., Battery Management System: BMS, etc.), a relay required for precharging, a shunt resistor, and conductive wiring such as a bus bar or conductor wire. In addition, the support base may be provided with screws, screw holes, and fixing devices for fixing these electrical components. By integrating the electrical components with the support base using these fixing devices, it is possible to connect the electrical components such as the safety mechanism to the battery group via the conductive wiring and electrically connect to the external terminal. This makes it possible to introduce an insulating material between the terminal surfaces of each battery group, thereby making it possible to provide a battery pack that has high heat dissipation while also having crush safety.

[0020] The present invention is not particularly limited to the method and positional relationship of attaching safety mechanisms to these support bases. For example, these devices may be arranged or built into the upper, lower, side, or interior of an insulating support base. There is also no particular limitation on the order of electrical arrangement of these devices. The size and shape of the support base may be any size or shape as long as the insulation between the two battery groups is ensured when the battery groups approach each other due to crushing. For example, the support base may be a thin plate, or may have a complex three-dimensional shape to store each electrical component, as in the support base exemplified in the present invention.

[0021] When the battery group is arranged as in the present invention, the effects of the present invention can be obtained regardless of how the cells constituting the battery group are electrically connected to each other. For example, the effects of the present invention can be obtained even if the battery groups are connected in parallel by devising wiring for the battery groups. Here, as an example, a case will be described in which the cells in each battery group are connected in series, and two opposing battery groups are also connected in series.

[0022] Examples of the method for connecting the battery groups in series after the battery groups are arranged to face each other include the following. (A) A method of directly connecting battery groups using bus bars. In this case, taking into consideration workability, the bus bars may be electrically connected to each other using a portion of the bus bar or wiring extended for connection, using a method such as screws or welding. However, the method of electrical connection is not limited to these. (B) A method of electrically connecting the bus bars to each other via a support base including an insulating member as a constituent member as described above. In this case, it is preferable that a conductive part such as a bus bar or a cable is built into the support base and that the electrical connection is made via the conductive member. (C) A method of directly connecting battery groups using cables. (D) The above-mentioned method includes a method of electrically connecting the cables to each other via a support base including an insulating material as a component.

[0023] In addition to electrically connecting the cells in series or parallel to each other, it is preferable that the cells of the battery group are physically restrained by using a fixing jig. When the side of the cell is covered with an insulating material, the material of the fixing jig may be a material having high thermal conductivity such as aluminum, aluminum die-cast, copper, or iron. When the side of the cell is not covered with an insulating material, polypropylene, polyamide, polyetherimide, PPS, PPA, PBT, or a highly thermally conductive resin may be used. The method of restraint of the present invention is not limited. For example, the effect was obtained when two battery groups were bound using one set of fixing jigs, or when they were fixed using two sets of fixing jigs. The effect of the present invention was also obtained when at least a part of the fixing jig was a housing.

[0024] The method of contacting the housing with the battery group and the support base and other components is not particularly limited, and the effects of the present invention can be achieved by, for example, bonding with an adhesive or connecting via fixing devices such as bolts and nuts. In this embodiment, the shape of the housing is exemplified as a rectangular parallelepiped, but the shape is not particularly limited. Furthermore, the effects of the present invention are not limited to the current application conditions and cooling conditions for the battery pack.

[0025] In the support base exemplified in the present invention, bus bars and conductors with good thermal conductivity are arranged, so if a mechanism for releasing heat from the support base is provided, a cooling effect can be expected. For example, a cooling mechanism such as a heat pipe or a cooling tube may be provided in the part that is in thermal contact with the support base.

[0026] Furthermore, even if the housing is provided with a cooling mechanism such as a jacket or piping using fins or other coolants, the effect can be obtained by adopting the structure of the present invention.

[0027] The type of the housing is not particularly limited, and may be, for example, a resin housing or a metal housing. It is preferable that the housing is made of a thermally conductive metal such as aluminum, aluminum die-cast, copper, or iron.

[0028] In the example of the present invention, the external terminals emerging from the lid are positioned at the top of the space where electrical equipment can be placed, but the external terminals can also be positioned at the top of the pressure binding jig. In this case, too, the effects of the present invention can be obtained by adopting the structure of the present invention. In the example, a method of electrical connection is illustrated in which conductors such as bus bars are placed on a support base that includes insulating materials as its constituent members, and various electrical equipment is connected to the conductors using screws.

[0029] Example 1 The present invention will be described in further detail below based on examples and comparative examples.

[0030] First, an overview of a battery pack 100 according to the present invention will be described with reference to FIG. 3. FIG. 3 is an exploded perspective view of the battery pack 100 according to the present invention. The battery pack 100 according to the present invention is composed of two battery groups 10A and 10B, a metal housing 7 that houses the two battery groups 10A and 10B, a lid 8 that covers an opening of the housing 7, and a support base 4 on which electrical equipment (not shown in FIG. 3) is arranged. The support base 4 is arranged in an electrical equipment arrangement space 4A between the battery group 10A and the battery group 10B. The battery groups 10A and 10B are arranged so that the terminals (positive terminal 12, negative terminal 13) of the single cells 1 face each other, and are electrically connected to each other by wiring 6. An external terminal 9 is arranged on the lid 8 and is electrically connected to the wiring 6, and power is taken out from the battery pack 100 via the external terminal 9.

[0031] The battery groups 10A and 10B will be described in detail with reference to Fig. 1. The unit cells 1 are composed of a pair of wide sides, a pair of narrow sides, a bottom surface, and a top surface, and a positive electrode terminal 12 and a negative electrode terminal 13 are disposed on the top surface. Insulating spacers 11 are disposed between the unit cells 1, and the unit cells 1 are stacked so that the positive and negative terminals are alternated.

[0032] A pair of pressurizing restraining jigs 3 are disposed facing the wide surface of the uppermost cell 1 and the wide surface of the lowermost cell 1, respectively.

[0033] In addition, a pair of pressure restraining jigs 2 are disposed facing narrow side surfaces of the unit cell 1, and the pressure restraining jigs 2 and 3 are fixed to each other by a fixing metal fitting 5.

[0034] 2 shows the connections between the wiring 6 and the individual cells 1. The wiring 6 is divided into three types: wiring 6A connected to the external terminals 9, wiring 6C connecting the individual cells 1 with each other, and wiring 6B connecting the battery groups 10A and 10B. These wirings 6A, 6B, and 6C are connected to form the battery group 10A and the battery group 10B. The wiring 6B of the battery group 10A and the wiring 6B of the battery group 10B are connected to each other.

[0035] 4 shows a view from the opening side of the housing 7 with the lid 8 of FIG. 3 removed. The support base 4 arranged between the first battery group 10A and the second battery group 10B is connected to a wiring 6A, and this wiring 6A is electrically connected to a support base terminal portion 6A1 which is connected to an external terminal 9 provided on the lid 8. A BMS (substrate) 20, a shunt resistor 21, a fuse 22, and a relay 23 are assembled to the support base 4. The assembly method will be described in detail with reference to FIG. 5. An insulating material, such as an insulating resin material, is used for the support base.

[0036] Next, the support base 4 will be described with reference to Fig. 5. The BMS 20 and the shunt resistor 21 are arranged on one surface of the support base 4, and the fuse 22 and the relay 23 are arranged on the other surface. The BMS 20 and the shunt resistor 21 are assembled together, with one side connected to the wiring 6A and the other side connected to the support base terminal portion 6A1.

[0037] Since the fuse 22 and relay 23 arranged on the other surface are large components, two recesses are provided on the other surface, in which the fuse 22 and relay 23 are housed. This structure allows the integrated assembly of the support base 4 and the electrical equipment to be made compact. The fuse 22 and relay 23 may be integrated by connecting them to each other with the connecting wire 6A2, and then assembled to the support base 4. Furthermore, the electrical equipment is assembled using parts such as screws, but the assembly method is not limited to this.

[0038] Next, the characteristic features of this embodiment will be described with reference back to FIG.

[0039] In this embodiment, the battery groups 10A and 10B are housed in the housing 7 so that the four surfaces of the battery groups 10A and 10B, that is, the two side surfaces of the battery groups 10A and 10B (the surfaces on which the pressurizing binding jig 2 is arranged), the bottom surface of the cell 1, and the bottom surface of the battery groups 10A and 10B (the surface on which the lower pressurizing binding jig 3 is arranged) are in direct contact with the housing. Therefore, when two or more battery groups 10A and 10B are housed, the cooling performance is most improved. On the other hand, in order to improve the cooling efficiency, it is necessary to house the battery groups 10A and 10B so that the surface on which the terminals of the battery group 10A are arranged and the surface on which the terminals of the battery group 10B are arranged face each other. Therefore, in the present invention, the electrical components required for the battery pack 100 are assembled on an insulating support base and arranged between the battery group 10A and the battery group 10B. Therefore, while improving the cooling performance of the battery pack 100, the insulation of the two battery groups 10A and 10B can be secured, and the battery pack 100 can be prevented from becoming large. A more detailed explanation will be given of the fact that this can prevent the battery pack 100 from becoming larger. If the terminal side of the battery group 10A and the terminal side of the battery group 10B are originally intended to face each other, a creepage distance must be provided for the two battery groups, which increases the volume of the battery pack 100. Therefore, the space required to provide the creepage distance for the battery groups 10A and 10B can be overlapped with the space in which the support base is disposed, thereby preventing the battery pack 100 from becoming larger.

[0040] Another advantage of this structure is that the electrical components are first integrated into the support base 4 before the battery pack 100 is constructed. Therefore, there is no need to arrange the electrical components in the narrow space between the battery group 10A and the battery group 10B; the work can be completed by simply fixing the support base 4 to which the electrical components are fixed, to the housing 7 or the like, all at once, improving workability when fabricating the battery pack 100.

[0041] In this embodiment, the substrate (20) is disposed on one side of the support base 4, and the large components, the relay (23) and the fuse (22), are disposed on the other side. This structure allows the BMS 20, which is a planar member, to be disposed on one side, and no unnecessary uneven space is generated compared to a structure in which the relay 23 is disposed on one side of the support base 4 and the fuse 22 is disposed on the other side. This contributes to miniaturization.

[0042] Although a bus bar is used as the wiring 6 in this embodiment, a cable may also be used.

[0043] A current was applied to the battery pack prepared as described above. At this time, a member with low thermal conductivity was placed on the underside of the casing, and the current was applied, and the test results were obtained in a thermostatic chamber with almost no air flow. The current value was applied so that the heat generation amount from the battery was calculated from the current value to be 3 W on average. In this example, the temperature behavior when the battery pack reached a nearly steady state after the above conditions were applied is shown in FIG. 11.

[0044] Example 2 In this example, an electrode consisting of an Al current collector foil and a layered positive electrode material, etc., was used as the positive electrode, and an electrode consisting of an Al current collector foil and a spinel oxide was used as the negative electrode, and six unit cells each formed by winding these electrodes were stacked as shown in Fig. 1, and the periphery was fixed using a pressure fixture to obtain a battery group. In this example, the same current application conditions and surrounding cooling environment as in Example 1 were applied to the battery with the above configuration, and the results when it reached a nearly steady state are shown in Fig. 12.

[0045] Comparative Example 1 An electrode made of an Al current collector foil and a positive electrode material having a layered structure, and an electrode made of a Cu current collector foil and a carbon material as a negative electrode were used as a single battery formed by winding these electrodes, and 12 single batteries 1 were connected in series to form a single battery group 10A, 10B. At this time, a spacer 11 similar to that in Example 1 was placed between the single batteries 1. The battery group was arranged such that the wide surface of the single batteries 1 was approximately perpendicular to the bottom surface of the housing as shown in FIG. 9, and the 12 battery groups were fixed using a pressure jig (22, 33) for fixing to obtain a battery group 10C. The housing and the battery group 10C were fixed using screws. Note that FIG. 9 is a plan view of the housing cover surface as seen from the top surface. In this comparative example, as in Example 1, electrical equipment was placed on the path connecting the external terminal 9 to the single batteries 1. The electrodes of the battery group 10C were electrically connected to the external terminals by connecting the same electrical equipment as in Example 1 using a bus bar and a cable. In this comparative example, the battery having the above-mentioned configuration was subjected to the same current application conditions and surrounding cooling environment as in Example 1, and the results when the battery reached a substantially steady state are shown in FIG.

[0046] Comparative Example 2 The battery configuration described in Patent Document 1 was simulated and used as a comparative example. Specifically, an electrode made of an Al current collector foil and a positive electrode material having a layered structure, and an electrode made of a Cu current collector foil and a carbon material were used as a positive electrode, and a single cell 1 formed by winding these electrodes was used, and a group consisting of six single cells was formed as in Example 1 so that only the battery group 10D could be compared with Example 1. The battery group 10D was arranged so that the sides of the battery group 10D were physically contacted with each other. Electrical equipment was arranged on the path connecting the electrodes of the battery group 10D from the external terminal, and the electrical equipment was electrically connected from the electrode part to the external terminal by connecting the same electrical equipment as in Example 1 using a bus bar and a cable. In addition, in order to provide approximately the same cooling environment as in Example 1, a case 77 and a lid 88 were newly provided around the battery group for a comparative experiment. The battery group 10D configured in this way was given the same current application conditions and surrounding cooling environment as in Example 1, and the results when it reached a nearly steady state are shown in FIG. 11.

[0047] Comparative Example 3 In this comparative example, an electrode made of an Al current collector foil and a positive electrode material having a layered structure was used as the positive electrode, and an electrode made of an Al current collector foil and a spinel oxide was used as the negative electrode, and six unit cells formed by winding these electrodes were stacked as shown in Fig. 10, and the periphery was fixed using a pressure jig for fixing, thereby obtaining a battery group 10D. In this comparative example, the same current application conditions and surrounding cooling environment as in Example 1 were applied to the battery having the above configuration, and the results when the battery reached a nearly steady state are shown in Fig. 12.

[0048] As a result of applying the conditions shown in the present embodiment and the comparative example to the battery group, when the temperature of the battery group reached a substantially steady state, the battery temperature rose compared to the ambient temperature. In Figures 11 and 12, the temperature rise rate of the battery that had the largest temperature rise from the ambient temperature among the battery group present in Comparative Example 1, which had the largest temperature rise among the embodiments and comparative examples of the present invention, was set as 100%, and the temperature rise rate of the single cells present in each example was compared.

[0049] For Comparative Example 1, the cell numbers are assigned in order from the leftmost cell in Fig. 9. On the other hand, for all the stacked battery groups except Comparative Example 1, cells with the same height position from the bottom surface had approximately the same temperature, so only six cells with different heights are listed. On the other hand, in the examples except Comparative Example 1, the height from the bottom surface of the housing increases in ascending order of cell number in the figure.

[0050] The results of each figure are explained in detail below.

[0051] Figure 11 shows the temperature rise ratios for Comparative Examples 1 and 2, as well as for Example 1, which is an example in which the present invention is applied. It can be seen from the figure that in Comparative Example 1, the temperature of cells No. 6 and 7, which are the central part of the stacked batteries, is the highest. This is because in the battery near cell No. 7, the amount of heat generated by the surrounding batteries is not dissipated, so not only the temperature of the battery itself but also the temperature of the surrounding batteries is high, and since there is no temperature difference, heat does not flow easily, resulting in a high battery temperature.

[0052] On the other hand, as shown in FIG. 11, in Example 1 and Comparative Example 2, the number of stacked battery groups is reduced, and thus the temperature rise rate of the 6 battery groups is reduced compared to Comparative Example 1, in which 12 battery groups are stacked. It is believed that this influence has led to a suppression of temperature rise in Comparative Example 2 compared to Comparative Example 1. In addition, in Example 1, the surfaces on which the external terminals of the battery groups are arranged face each other within the casing, and the battery groups are not thermally and physically connected to each other. It is believed that this reduces the thermal resistance compared to Comparative Example 2, and reduces the temperature of the single cells even more than Comparative Example 2.

[0053] Fig. 12 shows a comparison between the configuration of the present invention and the configuration of the known example, using six single cells formed by winding an electrode consisting of an Al current collector foil and a layered positive electrode material as a positive electrode, and an electrode consisting of an Al current collector foil and a spinel oxide as a negative electrode. The results in Fig. 12 show that the effect of the present invention is observed even when the type of battery is changed.

[0054] Example 3 Next, a description will be given of Example 3. Example 3 differs from Example 1 in that a water-cooling jacket 107 is provided on the side of the housing 7. Note that the same components as those in Example 1 are given the same reference numbers.

[0055] Fig. 6 shows the structure of Example 3. In this example, a water-cooling jacket 107 is provided on the side of the housing 7 as shown in Fig. 6. Therefore, in addition to the effect of Example 1, the cooling performance can be further improved.

[0056] Example 4 Next, a description will be given of Example 4. Example 4 differs from Example 1 in that fins 177 for cooling are provided on the side surface of the housing 7. Note that the same components as those in Example 1 are given the same reference numbers. Fig. 7 shows the structure of the fourth embodiment. In this embodiment, fins 177 for air cooling are provided on the side of the housing 7 as shown in Fig. 7. Therefore, in addition to the effect of the first embodiment, the cooling performance can be further enhanced. Also, since the air cooling method is used in this embodiment, the cooling performance is lower than that of the third embodiment, but devices required for water cooling are not required, and the vehicle can be made compact when mounted on the vehicle.

[0057] Example 5 Next, a description will be given of Example 5. Example 5 differs from Example 1 in that the pressurizing binding member 2 also serves as the housing 277. Note that the same configurations as in Example 1 are given the same reference numbers.

[0058] Fig. 8 shows the structure of Example 5. In this example, as shown in Fig. 8, the side surface of the housing 277 is in direct contact with the battery groups 10A and 10B, and the pressurizing restraining jig 3 is connected to the housing 277.

[0059] As shown in FIG. 8, in this embodiment, the pressure binding member 3 is directly connected to the housing 277. In addition, in order to increase the contact area between the pressure binding jig 3 and the housing 277, in this embodiment, the housing side recesses 277A and 277B for accommodating the pressure binding jig 3 and the housing side protrusion 277C arranged between the two housing side recesses 277A and 277B are provided. With this structure, the side portions of the battery groups 10A and 10B directly contact the housing 277 without the pressure binding jig, improving the cooling performance. In addition, the pressure binding jig 3 of the battery groups 10A and 10B is arranged in the housing side recesses 277A and 277B, so that the contact area between the pressure binding jig 3 and the housing 277 is increased, and heat dissipation from the pressure binding jig 3 is promoted. Furthermore, the two pressure binding jig 3 are also in contact with the housing side protrusion 277C, so that heat dissipation from the pressure binding jig 3 is further promoted.

[0060] The present invention is briefly summarized above.

[0061] The battery pack 100 of the present invention has a battery cell (1) with a pair of wide side surfaces, a pair of narrow side surfaces, a bottom surface connecting the wide side surfaces and the narrow side surfaces, and a top surface on which external terminals are arranged, and is equipped with a first battery group (10A) in which a plurality of battery cells (1) are stacked with their wide side surfaces facing each other, a second battery group (10B) in which a plurality of battery cells (1) are stacked with their wide side surfaces facing each other, and a housing (7) that houses the first battery group (10A) and the second battery group (10B), and the surface on which the external terminals (12, 13) of the first battery group (10A) are arranged and the surface on which the external terminals (12, 13) of the second battery group (10B) are arranged are arranged opposite each other. With this structure, the four surfaces of the battery groups 10A, 10B, i.e., the two side surfaces of the battery groups 10A, 10B (the surfaces on which the pressurizing restraining jig 2 is positioned), the bottom surface of the single cell 1, and the bottom surface of the battery groups 10A, 10B (the surface on which the lower pressurizing restraining jig 3 is positioned), can be used for cooling by being in direct contact with the housing 7, thereby improving cooling performance.

[0062] Furthermore, in the battery pack (100) described in the present invention, electrical components are disposed in the space between the surface on which the external terminals (12, 13) of the first battery group (10A) are disposed and the surface on which the external terminals (12, 13) of the second battery group (10B) are disposed. With this structure, the space required to secure the creepage distance between the battery groups 10A, 10B can be used as storage space for electrical components, and the battery pack 100 can be prevented from becoming large.

[0063] In addition, the battery pack (100) according to the present invention has at least two of the electrical components, the board (20), the relay (23), and the fuse (22), so that two or more components can be assembled into one assembly, thereby improving workability.

[0064] The battery pack (100) according to the present invention is characterized in that the electrical components are each integrated with an insulating member. This structure ensures insulation between the battery groups 10A and 10B, and eliminates the need to arrange the electrical components in the narrow space between the battery groups 10A and 10B. Therefore, the support base 4 to which the electrical components are fixed can be fixed to the housing 7 or the like as a single unit, thereby ensuring insulation between the battery groups 10A and 10B and improving workability.

[0065] In addition, in the battery pack (100) described in the present invention, the electrical components are the board (20), the relay (23), and the fuse (23), and the board (20) is disposed on one side of the insulating member, and the relay (23) and the fuse (22) are disposed on the other side. With this structure, the BMS 20, which is a planar member, can be disposed on one side, and no unnecessary uneven space is generated compared to a structure in which the relay 23 is disposed on one side of the support base 4 and the fuse 22 is disposed on the other side. This contributes to miniaturization.

[0066] Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0067] 1 D cell 2. Pressurizing fixture 3. Pressurizing fixture 4 Support stand 5 Fixing bracket 6 Wiring 7. Cabinet 8 Cover 9 terminals 10A, 10B battery pack

Claims

1. A battery pack having a battery cell including a pair of wide side surfaces, a pair of narrow side surfaces, a bottom surface connecting the wide side surfaces and the narrow side surfaces, and a top surface on which external terminals are disposed, a first battery group in which a plurality of the battery cells are stacked with their wide side surfaces facing each other; a second battery group in which a plurality of the battery cells are stacked with their wide side surfaces facing each other; a housing that houses the first battery group and the second battery group, the first battery group and the second battery group are disposed in the housing such that their respective wide side surfaces that form the uppermost and lowermost parts do not face each other; a surface on which the external terminals of the first battery group are arranged and a surface on which the external terminals of the second battery group are arranged are arranged opposite to each other, and an insulating support base on which electrical equipment is arranged is arranged in a space between the surface on which the external terminals of the first battery group are arranged and the surface on which the external terminals of the second battery group are arranged; a surface of each of the first battery group and the second battery group opposite to the terminal faces an inner surface of the casing and does not face other battery groups; The battery pack is characterized in that a circuit board is disposed as the electrical equipment on one side of the support stand, and a relay and a fuse are disposed as the electrical equipment on the other side of the support stand.

2. 2. The battery pack according to claim 1, The battery pack according to claim 1, wherein the relay and the fuse are accommodated in a recess provided on the other side of the support base.

3. 2. The battery pack according to claim 1, the first battery group and the casing are in contact with each other via a pressure restraint jig, and the second battery group and the casing are in contact with each other via a pressure restraint jig.

4. 2. The battery pack according to claim 1, a first battery group and a second battery group in direct contact with each other; and a second battery group and a second battery group in direct contact with each other.

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