Power supply device

Abstract

This power supply device is provided with: a plurality of secondary battery cells each having a cell first end surface and a cell second end surface, the secondary battery cells being disposed in a posture in which the cell first end surfaces have the same planar shape; a heater unit that has a planar shape having a heater first surface and a heater second surface, the heater first surface being disposed in a posture facing the cell first end surfaces of the plurality of secondary battery cells; a first heat transfer sheet that is interposed between the cell first end surfaces of the plurality of secondary battery cells and the heater first surface and has thermal conductivity; a second heat transfer sheet that is disposed on the heater second surface side and has thermal conductivity; and an exterior case that has a case first surface and that defines a storage space for accommodating the plurality of secondary battery cells, the first heat transfer sheet, the heater unit, and the second heat transfer sheet.

Description

power supply

[0001] The present disclosure relates to a power supply device.

[0002] Power supply devices that power electrical devices include a plurality of rechargeable secondary battery cells, such as lithium-ion secondary batteries, connected in series or parallel and housed in an exterior case (see, for example, Patent Document 1). It is known that the performance of the lithium-ion batteries used in such power supply devices deteriorates when used at low temperatures. Therefore, to operate the devices at low temperatures, a heating mechanism, such as a heater for heating the secondary battery cells, has been proposed (see, for example, Patent Document 1). Patent Document 1 discloses a battery pack that includes a plurality of cylindrical batteries and a battery holder with individually partitioned battery housing spaces capable of housing each of the plurality of cylindrical batteries. The heating element is disposed so that its heating surface is in surface contact with a portion of the outer periphery of each cylindrical battery, and the heating element directly heats a portion of each cylindrical battery.

[0003] On the other hand, it is known that secondary battery cells generate heat during charging and discharging. Secondary battery cells deteriorate at high temperatures, so they need to be cooled. For this reason, cooling mechanisms for cooling multiple secondary battery cells have been proposed, such as adding an air-cooling fan or a cooling plate that circulates a refrigerant inside.

[0004] However, if a heating mechanism for heating and a cooling mechanism for cooling are simultaneously added to the secondary battery cells, there is a problem in that the power supply device becomes larger.

[0005] JP 2012-243535 A

[0006] One object of the present disclosure is to provide a power supply device that enables heating and cooling of multiple secondary battery cells with a simple configuration. Another object is to provide a power supply device that reduces temperature unevenness when heating multiple secondary battery cells. Note that the description of these objects and objects of the present disclosure does not preclude the existence of other objects and objects. Furthermore, it is not necessary for one embodiment of the present disclosure to solve all of these objects. Furthermore, other objects can be extracted from the description of the specification, drawings, and claims of the present disclosure.

[0007] A power supply device according to one embodiment of the present disclosure includes a plurality of secondary battery cells, each having a first cell end face and a second cell end face, and arranged in a position where the first cell end faces are flush with one another; a planar heater section having a first heater surface and a second heater surface, and arranged in a position where the first heater surface faces the first cell end faces of the plurality of secondary battery cells; a first heat transfer sheet having thermal conductivity and interposed between the first cell end faces of the plurality of secondary battery cells and the heater first surface; a second heat transfer sheet having thermal conductivity and arranged on the heater second surface side; and an outer case having a first case surface that defines a storage space for storing the plurality of secondary battery cells, the first heat transfer sheet, the heater section, and the second heat transfer sheet.

[0008] According to one embodiment of the power supply device of the present disclosure, a heater section is arranged on the first end face side of the secondary battery cell, and the secondary battery cell is heated according to the ambient temperature in which the power supply device is used, thereby suppressing performance degradation. When the secondary battery cell generates heat, the heat can be dissipated to the outside from the first end face side of the secondary battery cell via the second heat transfer sheet, which allows heating and cooling to be performed from the same end face side of the secondary battery cell, thereby providing the advantage of simplifying the configuration.

[0009] FIG. 1 is a perspective view of a power supply device according to a first embodiment. FIG. 2 is a perspective view of the power supply device of FIG. 1, viewed obliquely from below on the rear side. FIG. 3 is an exploded perspective view of the power supply device of FIG. 1. FIG. 4 is an exploded perspective view of the power supply device of FIG. 2. FIG. 5 is a further exploded perspective view of the power supply device of FIG. 3. FIG. 6 is a further exploded perspective view of the power supply device of FIG. 5. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 1. FIG. 8 is an exploded perspective view of a heater unit. FIG. 9 is a schematic diagram showing the thermal coupling portion between a secondary battery cell and a heater unit. FIG. 10 is an exploded perspective view showing the addition of a cooling plate to the power supply device of FIG. 2. FIG. 11 is a schematic diagram showing the thermal coupling portion between a secondary battery cell and a heater unit in a power supply device according to a modified example. FIG. 12 is a conceptual diagram showing a plan view of the results of a simulation of temperature changes during heating of the power supply device. FIG. 13 is a conceptual diagram showing the results of a simulation of temperature changes in a cross section taken along line XIII-XIII in FIG. 12. FIG. 14 is a conceptual diagram showing the results of a simulation of temperature changes during cooling of the power supply device. Fig. 15 is a schematic diagram showing a thermal coupling portion between a secondary battery cell and a heater unit of a power supply device according to embodiment 2. Fig. 16 is a plan view showing a pattern of the heater unit of a power supply device according to embodiment 2. Fig. 17 is a plan view showing a pattern of the heater unit of a power supply device according to embodiment 3.

[0010] The embodiments of the present disclosure may be specified by the following configurations and features.

[0011] In a power supply device according to another aspect of the present disclosure, in the above aspect, the exterior case has an opening on at least the first case surface, and the exterior case includes a thermally conductive bottom case that closes the opening on the first case surface and faces the second heat transfer sheet in the storage space. With the above configuration, heat generated by the secondary battery cells can be dissipated to the outside via the second heat transfer sheet and the bottom case, which have excellent thermal conductivity.

[0012] In addition, the power supply device according to another aspect of the present disclosure is any of the above-described aspects, further including a cooling plate connected in thermal coupling to the outer surface of the bottom case. With this configuration, the secondary battery cells are thermally coupled to the cooling plate via the second heat transfer sheet and the bottom case, and the secondary battery cells can be efficiently cooled by the cooling plate.

[0013] Furthermore, the power supply device according to another aspect of the present disclosure, in any of the above aspects, can further include a first insulating sheet interposed between the heater portion and the first heat transfer sheet.

[0014] Furthermore, the power supply device according to another aspect of the present disclosure may be any of the above-described aspects, further comprising a second insulating sheet interposed between the second heat transfer sheet and the bottom case. With this configuration, the heater unit and the secondary battery cells are insulated by the first insulating sheet, and the heater unit and the bottom case are insulated by the second insulating sheet, thereby improving safety.

[0015] Furthermore, in the power supply device according to any one of the above aspects, the heater section has a heating element disposed within a plane.

[0016] In a power supply device according to yet another aspect of the present disclosure, in any of the above aspects, the heater section has a sparser heating element density in a central region than in surrounding regions. With the above configuration, the heating elements of the heater section are arranged so that the central region, which is relatively easily heated, is sparser, while the surrounding regions, which are relatively easily heat-dissipating and less likely to increase in temperature, are denser than the central region, thereby making it possible to prevent uneven heating when heating multiple secondary battery cells with the heater section.

[0017] According to yet another aspect of the present disclosure, there is provided a power supply device including a plurality of adjacently arranged secondary battery cells, each having a first end face and a second end face, an exterior case that houses the plurality of secondary battery cells, and a heater unit that is arranged in a position facing the first end faces of the plurality of secondary battery cells, wherein the heater unit has a heating element disposed within a plane, and the density of the heating element is lower in a central region than in surrounding regions. With the above configuration, by arranging the heating element of the heater unit so that the peripheral region, where heat dissipation is relatively easier, is denser than the central region, it is possible to suppress uneven heating when the plurality of secondary battery cells are heated by the heater unit.

[0018] Furthermore, in the power supply device according to another aspect of the present disclosure, in any one of the above aspects, the heater section has a central region where the density of the heating elements is sparse, which is partially open.

[0019] Furthermore, in a power supply device according to another aspect of the present disclosure, in any of the above aspects, each of the plurality of secondary battery cells has a positive electrode on the second end surface of the cell, and the second end surfaces of the cells are connected to each other by a lead plate.

[0020] In addition, in a power supply device according to another aspect of the present disclosure, in any of the above aspects, no lead plate is provided on the first end face of the cell. With this configuration, by connecting the second end face of the secondary battery cell with a lead plate, the first end face of the cell where no lead plate is provided can be used for heating and heat dissipation, making it possible to achieve both electrical connection and a structure for heat dissipation.

[0021] Embodiments of the present disclosure will be described below with reference to the drawings. However, the embodiments described below are merely examples for embodying the technical concepts of the present disclosure, and the present disclosure is not limited to the following. Furthermore, this specification does not in any way specify the components set forth in the claims to be those of the embodiments. The dimensions, materials, shapes, relative positions, etc. of components described in the embodiments are not intended to limit the scope of the present disclosure, and are merely illustrative examples, unless otherwise specified. The size and positional relationships of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate components that are identical or of the same quality, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present disclosure may be configured with the same components, such that multiple elements are shared by one component, or conversely, the functions of one component may be shared by multiple components.

[0022] The power supply device of the present disclosure can be used as a backup power source for servers in stationary power storage applications, or as a power supply device for home, office, or factory use, as a power source for portable electrical equipment such as radios, electric cleaners, and power tools, as a driving power source for mobile objects such as electric carts, electric scooters, and assisted bicycles, and as a driving power source for vehicles such as hybrid cars and electric automobiles. Below, a power supply device used as a driving power source for power storage will be described as one embodiment of the present invention.

[0023] [Embodiment 1] A power supply device 100 according to Embodiment 1 of the present disclosure is shown in Figures 1 to 7. Figure 1 is a perspective view of the power supply device 100 according to Embodiment 1, Figure 2 is a perspective view of the power supply device 100 of Figure 1 as seen from diagonally below the rear side, Figure 3 is an exploded perspective view of the power supply device 100 of Figure 1, Figure 4 is an exploded perspective view of the power supply device 100 of Figure 2, Figure 5 is a further exploded perspective view of the power supply device 100 of Figure 3, Figure 6 is a further exploded perspective view of the power supply device 100 of Figure 4, and Figure 7 is a cross-sectional view taken along line VII-VII in Figure 1. The power supply device 100 shown in these figures includes an outer case 10, a battery module 2, a metal plate 20, a heater unit 30, a first heat transfer sheet 40, a second heat transfer sheet 50, and a circuit board 3.

[0024] (External Case 10) The external case 10 houses the battery module 2, metal plate 20, heater unit 30, circuit board 3, etc. The external shape of the external case 10 can be any shape that has an internal storage space 14. In the example shown in FIGS. 1 and 2, the external case 10 has a box-like shape that extends in one direction. The external case 10 has a first case surface 10a, a second case surface 10b, a third case surface 10c, a fourth case surface 10d, a fifth case surface 10e, and a sixth case surface 10f. The first case surface 10a and the second case surface 10b are opposed to each other and form the main surfaces of the external case 10. The third case surface 10c and the fourth case surface 10d are also opposed to each other and connect the first case surface 10a and the second case surface 10b. The fourth case surface 10d and the fifth case surface 10e are also opposed to each other and similarly connect the first case surface 10a and the second case surface 10b, and further connect the third case surface 10c and the fourth case surface 10d.

[0025] 3 to 6, the exterior case 10 is divided into three parts: a main case 11, a bottom case 12, and a front panel 13. The exterior case is not limited to a three-part configuration, and may be divided into two parts, for example, an upper case and a lower case, or may be divided into four or more parts.

[0026] The exterior case 10 is open at least on the first case surface 10a. In the example shown in Figures 3 to 6, the main case 11 is open on the right side surface corresponding to the first case surface 10a and on the front side corresponding to the third case surface 10c. The bottom case 12 closes the opening on the right side surface. The front panel 13 closes the third case surface 10c.

[0027] Such an exterior case 10 is made of a material with excellent strength and heat dissipation properties, such as a metal member such as a galvanized steel plate or a stainless steel plate. It is particularly preferable that the bottom case 12 be made of a material with high thermal conductivity. This allows for efficient thermal conduction and dissipation of heat from inside the exterior case 10 to the cooling plate 70 in a configuration in which a cooling plate 70 is fixed to the bottom case 12 as shown in FIG. 10 (described later). The exterior case 10 may also be made of a material with excellent insulation properties, such as a resin such as polycarbonate or PC-ABS alloy.

[0028] (Cooling Plate 70) The cooling plate 70 is thermally coupled to the outer surface of the bottom case 12. With this configuration, heat sources such as the rechargeable battery cells 1 housed in the outer case 10 are thermally coupled to the cooling plate 70 via the bottom case 12, allowing the cooling plate 70 to efficiently cool the rechargeable battery cells 1. The cooling plate 70 is preferably made of a material with excellent heat dissipation properties, such as aluminum or an alloy thereof. A heat sink with heat dissipation fins is even better. In addition, blowing air onto the first case surface 10a or the cooling plate 70 can promote heat dissipation and accelerate cell cooling.

[0029] The bottom case 12 faces a second heat transfer sheet 50 (described later) in the storage space 14. With this configuration, heat generated by the secondary battery cells 1 can be dissipated to the outside via the second heat transfer sheet 50 and the bottom case 12, which have excellent thermal conductivity.

[0030] As shown in Figures 3 to 7, etc., a storage space 14 is provided inside the exterior case 10 to store the battery modules 2 and the like. The exterior case 10 may be arranged vertically so that the metal plate 20 and heater unit 30 stored in the storage space 14 are positioned on the sides of the multiple secondary battery cells 1. As will be described later, by arranging the exterior case 10 vertically, it is expected that the temperature distribution will become more uniform due to the effects of heated air convection and the like.

[0031] (Battery Module 2) The battery module 2, also called a core pack, houses multiple rechargeable battery cells 1. The battery module 2 may also be composed of multiple battery blocks, each housing multiple rechargeable battery cells. In the examples shown in Figures 4, 6 to 7, etc., multiple cylindrical rechargeable battery cells 1 are housed and held horizontally in a battery holder 5.

[0032] The multiple secondary battery cells 1 are connected in series or in parallel via lead plates 7. The number of series connections or parallel connections can be set as desired according to the required specifications. In the example shown in Figure 4, a total of 280 secondary battery cells 1 are used in the entire battery module 2, forming a 20 series x 14 parallel connection, but the present invention is not limited to this configuration.

[0033] The battery holder 5 has multiple storage cylinders that individually store the rechargeable battery cells 1. For example, as shown in Figure 7, each battery holder 5 is divided into two, an upper part and an lower part, and the two storage cylinders hold the rechargeable battery cells 1 from above and below. Such battery holders 5 can be made of resin such as polycarbonate, which has excellent insulating properties.

[0034] (Secondary battery cell 1) Each secondary battery cell 1 has a first cell end surface 1A and a second cell end surface 1B. The first cell end surface 1A and the second cell end surface 1B are located on opposite sides of each other. The multiple secondary battery cells 1 are arranged in a battery holder 5 so that the first cell end surfaces 1A are flush with each other. This configuration facilitates thermal coupling between the heater unit 30 (described later) and the first cell end surface 1A.

[0035] Each secondary battery cell 1 may be a secondary battery cell with a cylindrical or rectangular outer shape. In the examples shown in Figures 4, 6, 7, etc., the cylindrical secondary battery cells 1 are horizontally placed and arranged in a staggered pattern. The number and arrangement of the secondary battery cells 1 are not limited to this example, and any number and arrangement can be used as appropriate. For example, cylindrical secondary battery cells may be arranged in a matrix.

[0036] Each secondary battery cell 1 has a positive and a negative electrode. Preferably, one of the positive and negative electrodes is provided on a first cell end surface 1A of the secondary battery cell 1, and the other is provided on a second cell end surface 1B. In the example shown in FIG. 7 , the second cell end surface 1B is located on the bottom side of the outer can, and the outer can serves as the negative electrode. Such secondary battery cells 1 can be any known secondary battery, such as a lithium-ion secondary battery, a nickel-metal hydride battery, or a nickel-cadmium battery.

[0037] (Cell ejection mechanism 1a) The exterior can of each secondary battery cell 1 is provided with a cell ejection mechanism 1a, as shown in Fig. 7. The cell ejection mechanism 1a opens in response to an increase in internal pressure of the exterior can, and releases gas inside the exterior can to the outside. This cell ejection mechanism 1a is provided, for example, on the cell second end surface 1B side of the secondary battery cell 1, preferably on the side where the positive electrode is provided.

[0038] (Gas exhaust port 15) Meanwhile, the exterior case 10 is provided with a gas exhaust port 15 for releasing high-pressure gas to the outside when the cell exhaust mechanism 1a of the secondary battery cell 1 is opened and the gas is discharged. As shown in Fig. 1 , in the power supply device 100 according to the first embodiment, the gap between the first case 11 and the second case 12 that constitute the exterior case 10, or the gap between the first case 11 and the third case 13, etc., serves as the gas exhaust port 15. Note that the exterior case may also be configured to have an opening formed therein as the gas exhaust port.

[0039] (Lead Plates 7) Lead plates 7 are arranged on the side surfaces of the battery holder 5. The lead plates 7 connect the electrodes of the cell second end surfaces 1B of the rechargeable battery cells 1 to each other, connecting multiple rechargeable battery cells 1 in series or parallel. In the example shown in FIG. 3 , the cell second end surfaces 1B of 280 rechargeable battery cells 1 are connected to each other with lead plates 7, and the rechargeable battery cells 1 are connected in 20 series and 14 parallel configurations. Note that the number and arrangement of rechargeable battery cells, the number of series and parallel connections, etc. are not limited to this example, and any number and arrangement can be used as appropriate. These lead plates 7 are made of metal plates with excellent conductivity, such as aluminum, nickel, or copper.

[0040] Furthermore, no lead plate 7 is provided on the cell first end surface 1A side of the battery module 2. This configuration facilitates thermal coupling with the heater unit 30. That is, the cell first end surface 1A side of the secondary battery cell 1 serves as the thermal coupling surface with the heater unit 30, and the cell second end surface 1B side serves as the electrical connection surface for connection with the lead plate 7. This simplifies the configuration and also facilitates electrical connection and temperature management. Furthermore, in this embodiment, heating and cooling of the secondary battery cell 1 are performed on the thermal coupling surface side. In this manner, the conflicting functions of heating and cooling, which were previously performed separately, are performed on the same surface, thereby simplifying the configuration for temperature management of the secondary battery cell 1 and contributing to the miniaturization and cost reduction of the power supply device 100.

[0041] (Bus Bars 8) Blocks of multiple secondary battery cells 1 connected by lead plates 7 are further connected by bus bars 8. Bus bars 8 are made of a metal with excellent conductivity, such as aluminum, nickel, or copper.

[0042] (Circuit Board 3) The battery module 2 is connected to the circuit board 3 via lead plates 7. The circuit board 3 is equipped with a charge / discharge circuit that charges and discharges the rechargeable battery cells 1, a protection circuit that monitors the voltage and temperature of the rechargeable battery cells 1 and cuts off the current in the event of an abnormality, and other such circuits. The circuit board 3 is made of a glass epoxy board or the like. The circuit board 3 is held by a board holder 4. In the example shown in Figures 3 to 6, the board holder 4 is disposed on an end surface of the battery module 2 in the thickness direction. The board holder 4 is covered by a front panel 13. The front panel 13 is connected to connectors on the circuit board 3 and has external connection terminals.

[0043] (Metal Plate 20) The metal plate 20 defines a gas exhaust path inside the exterior case 10 that guides gas released when the cell ejection mechanism 1a of any of the multiple secondary battery cells 1 is opened to the gas exhaust port 15. The gas exhaust path is formed on the side of the battery module 2, on the side where the cell ejection mechanism 1a of each secondary battery cell 1 is provided, i.e., on the cell second end surface 1B side. In the example of FIG. 7 , the gas exhaust path is formed between the left side of the battery module 2 and the inner surface of the main case 11 that forms the case second surface 10b of the exterior case 10. Therefore, each secondary battery cell 1 that constitutes the battery module 2 is held in a position where the end surface where the cell ejection mechanism 1a is provided faces left in the figure. The gas exhaust path defined by the metal plate 20 forms, for example, a gas duct.

[0044] 3 to 6 is formed to have a size and shape approximately equal to that of the end face of the battery module 2. The metal plate 20 is also configured to have enough strength to withstand high-temperature, high-pressure gas when it is released from the cell ejection mechanism 1a. Such a metal plate 20 is made of a metal with excellent thermal conductivity, such as a galvanized steel plate or a stainless steel plate.

[0045] (Heater Unit 30) The heater unit 30 is thermally coupled to the battery module 2 and heats the secondary battery cells 1 when necessary. Generally, a preferred operating range is defined for secondary battery cells to ensure proper operation. For example, in cold regions, low environmental temperatures can prevent the cells from performing adequately and can cause deterioration. Therefore, when the ambient temperature is low, it is necessary to heat the secondary battery cells. In this embodiment, the heater unit 30 is operated to heat the secondary battery cells 1.

[0046] The heater section 30 is formed in a planar shape having a first heater surface 31 and a second heater surface 32. The first heater surface 31 and the second heater surface 32 are located on opposite sides of each other. The heater section 30 is disposed in a position in which the first heater surface 31 faces the first cell end surfaces 1A of the multiple secondary battery cells 1. In the examples shown in FIGS. 3 to 6 , the heater section 30 is disposed on the right side of the battery module 2, i.e., between the battery module 2 and the bottom case 12 that constitutes the first case surface 10a of the exterior case 10.

[0047] The heater section 30 has a heating element 34 arranged within its surface. An example of the configuration of the heater section 30 is shown in the exploded perspective view of Figure 8. As shown in this figure, the heater section 30 has a heating element 34 formed in a predetermined pattern sandwiched between thermally conductive films 33. The heater section 30 with this structure generates heat by Joule heat or the like when electricity is passed through the heater wire, which is the heating element 34.

[0048] Preferably, the heater section 30 is formed in a thin sheet shape. The use of a thin, planar heater section 30 contributes to a thinner and more compact power supply device 100. Such a planar heater section 30 may be a PTC heater, an aluminum etching heater, an electric heating wire heater, or the like.

[0049] (First Heat Transfer Sheet 40) A first heat transfer sheet 40 is interposed between the first cell end surfaces 1A of the multiple secondary battery cells 1 and the first heater surface 31. The first heat transfer sheet 40 is made of a material with excellent thermal conductivity and efficiently conducts heat generated by the heater unit 30 to the first cell end surfaces 1A. Furthermore, if gaps form at the interface between the first heat transfer sheet 40 and the first cell end surfaces 1A or at the interface between the first heat transfer sheet 40 and the heater unit 30, an air layer is formed, creating a heat insulating effect. Therefore, the first heat transfer sheet 40 is preferably made of a flexible material to ensure its surface is flexible enough to fill these interfaces without gaps. Additionally, insulating properties are preferable to insulate the end surfaces of the secondary battery cells 1. Silicone resin or the like is a suitable material for this purpose.

[0050] The first heat transfer sheet 40 is formed to have approximately the same size as the heater section 30. In the examples shown in Figures 3 to 6, four heat transfer sheets are arranged as the first heat transfer sheet 40 between the side surface of the battery module 2, that is, the right side in the figures, and the left side of the heater section 30.

[0051] (Second Heat Transfer Sheet 50) A second heat transfer sheet 50 is disposed on the second heater surface 32 side of the heater unit 30. In the examples of FIGS. 5 and 9, the second heat transfer sheet 50 is interposed between the heater unit 30 and the bottom case 12. This arrangement allows heat dissipation from the secondary battery cells 1 to occur on the bottom case 12 side, which constitutes the first case surface 10a of the outer case 10. Like the first heat transfer sheet 40, this second heat transfer sheet 50 is preferably made of a material with excellent thermal conductivity. Furthermore, it is preferably made of a flexible material so that the surface of the second heat transfer sheet 50 is flexible. Additionally, it is more preferable that the second heat transfer sheet 50 have insulating properties so as to insulate the end faces of the secondary battery cells 1. Silicone resin or the like is a suitable material for this purpose.

[0052] Rechargeable battery cells generate heat during charging and discharging, and cooling them is important for stable long-term use. As mentioned above, rechargeable battery cells sometimes need to be heated depending on the ambient temperature, and sometimes need to be cooled. To achieve these conflicting functions, conventionally, a heating mechanism and a cooling mechanism for the rechargeable battery cell were installed separately. However, the space available for installing these mechanisms around the rechargeable battery cell was limited, leading to an increase in the size of the power supply device and a complex configuration. In particular, rechargeable battery cells require lead plates for electrical connection, further limiting space.

[0053] In contrast, in this embodiment, the configuration is simplified by arranging a heating mechanism for heating the secondary battery cell 1 and a heat dissipation mechanism for dissipating heat from the secondary battery cell 1 on the cell first end surface 1A side where the heater unit 30 is installed. Specifically, as shown in the schematic cross-sectional view of Figure 9, a second heat transfer sheet 50 is arranged on the second heater surface 32 side of the heater unit 30 and thermally coupled to the exterior case 10, thereby thermally coupling the first cell end surface 1A of the secondary battery cell 1 to the bottom case 12 of the exterior case 10 from the first heat transfer sheet 40 on the heater first surface 31 side, via the heater unit 30 and the second heat transfer sheet 50, thereby forming a heat conduction path that dissipates heat to the outside of the power supply device 100 through the exterior case 10.

[0054] In this way, by sandwiching the heater section 30 between the first heat transfer sheet 40 and the second heat transfer sheet 50, it is possible to make it function as an integrated heat transfer layer 9. When heating the secondary battery cell 1, as shown by the upward arrow in Fig. 9, the heater section 30 included in the heat transfer layer 9 can heat the secondary battery cell 1 from the bottom surface. When cooling the secondary battery cell 1, as shown by the downward arrow in Fig. 9, it is possible to transfer heat generated by the secondary battery cell 1 to the bottom case 12 side via the heat transfer layer 9.

[0055] 1 to 7 show an example in which the power supply device 100 is placed vertically, in other words, the internal secondary battery cells 1 are in a horizontal position, but the present disclosure is not limited to this position, and the power supply device may be placed horizontally, in other words, the secondary battery cells 1 may be placed in a vertical position, as shown in Fig. 9. In this case, when the secondary battery cells 1 are heated, heat is transferred upward by the heater unit 30 placed on the first surface side of the cell, i.e., the bottom surface side, which is preferable because it coincides with the direction of thermal convection.

[0056] Furthermore, connecting a cooling plate 70 to the exterior case 10 can further promote heat dissipation from the power supply device. In the example shown in Fig. 10, the cooling plate 70 is fixed in thermal connection to the outer surface of the bottom case 12. With this configuration, heat sources such as the secondary battery cells 1 housed in the exterior case 10 are thermally connected to the cooling plate 70 via the second heat transfer sheet 50 and the bottom case 12, allowing the cooling plate 70 to efficiently cool the secondary battery cells 1. The cooling capacity of the cooling plate 70 can be increased by providing heat dissipation fins or by providing a refrigerant circulation path within it.

[0057] (First insulating sheet 61) A first insulating sheet 61 may be interposed between the heater section 30 and the first heat transfer sheet 40. The first insulating sheet 61 is made of a material that is insulating and thermally conductive, such as silicone resin. By interposing the first insulating sheet 61 between the heater section 30 and the first heat transfer sheet 40, the secondary battery cell 1 can be insulated from the heater section 30 and the outer case 10, thereby improving safety.

[0058] (Second insulating sheet 62) A second insulating sheet 62 may be interposed between the second heat transfer sheet 50 and the bottom case 12. Like the first heat transfer sheet 40, the second insulating sheet 62 is made of a material that has insulating and thermally conductive properties, such as silicone resin. By interposing the second insulating sheet 62 between the second heat transfer sheet 50 and the bottom case 12, the secondary battery cells 1 can be similarly insulated from the heater unit 30 and the outer case 10, thereby improving safety.

[0059] [Modifications] The first insulating sheet 61 and the second insulating sheet 62 may be omitted depending on the application and specifications. For example, if the first heat transfer sheet 40 and the second heat transfer sheet 50 are insulating and can withstand sufficient pressure, the first insulating sheet 61 and the second insulating sheet 62 can be omitted as shown in Fig. 11. Conversely, if the first heat transfer sheet 40 and the second heat transfer sheet 50 are not insulating, or if they are insulating but cannot withstand sufficient pressure alone, the first insulating sheet 61 and the second insulating sheet 62 can be added as appropriate to increase insulation and improve safety.

[0060] The heater section may be formed as a single piece, or multiple heater pieces may be arranged on the metal plate to cover it. The heater section 30 shown in Figures 3 to 6 is formed to be approximately the same size and shape as the metal plate 20. However, the size of the heater section 30 does not necessarily have to be the same as the metal plate 20, and it may have a smaller area than the metal plate. In particular, when the exterior case 10 is placed vertically as shown in Figure 7, etc., thermal convection occurs, making the upper side more likely to be heated. Therefore, the height of the heater section may be lower than the metal plate, and the bottom sides of the heater section and the metal plate may be roughly aligned, leaving an exposed area above the metal plate that is not covered by the heater section.

[0061] (Simulation Results) Simulation results for the power supply device 100 according to embodiment 1 when heated by the heater unit 30 are shown in FIGS. 12 and 13. FIG. 12 shows the simulation results as viewed from the second case surface 10b, i.e., the negative electrode side of the secondary battery cells 1 (ambient temperature 0°C). The area where one heater unit 30 is located is indicated by a dashed line. FIG. 13 shows the simulation results for a cross section taken along line XIII-XIII in FIG. 12. As shown in these figures, it was confirmed that the heater unit 30 was able to heat 280 secondary battery cells 1 approximately evenly.

[0062] 14 shows the simulation results for cooling the secondary battery cells 1 (ambient temperature 45°C). As shown in this figure, it can be seen that the central part of the battery module 2, where the secondary battery cells 1 are densely packed, is particularly difficult to cool, and the temperature in this part is relatively high.

[0063] In addition, as shown in Figure 9, etc., in a configuration in which both sides of the heater section 30 are sandwiched between a first heat transfer sheet 40 and a second heat transfer sheet 50 so as to function both to heat and cool the secondary battery cell 1, the thermal conductivity of the core material, the heater section 30, is poor, and this is thought to be one of the reasons why the thermal conductivity of the heat transfer layer 9 as a whole is not high.

[0064] On the other hand, when heating a large number of secondary battery cells 1 with the planar heater section 30, the central region within the first heater surface 31 is surrounded by other secondary battery cells 1, so heat is less likely to escape from the central region and the region is relatively easy to heat. Conversely, the peripheral regions have fewer surrounding secondary battery cells 1, so heat is more likely to escape to the outside of the heater section 30 and the region is considered to be more difficult to heat.

[0065] In view of these factors, it is believed that more uniform heating can be achieved by arranging the heating elements 34 so that the peripheral areas, which are difficult to heat, are densely packed and the central area, which is easy to heat, is sparsely packed, rather than by making the planar heater section 30 exert a uniform heating capacity regardless of location. Furthermore, sparsely packing the central area means that the heat transfer layer 9 is partially missing heater sections 30, as shown in Figure 15, creating a state where gaps exist. In this case, the absence of heater sections 30 that obstruct heat conduction can be expected to improve thermal conductivity, as indicated by the downward arrows in Figure 15.

[0066] [Embodiment 2] In this way, by devising the arrangement of the heating elements 34 that make up the heater section 30, further improvements can be achieved in heat dissipation and cooling of the secondary battery cells 1. Such an example is shown in Fig. 16 as a power supply device according to embodiment 2. Note that in the power supply device according to embodiment 2, components that are the same as those in embodiment 1 and the like described above are given the same reference numerals and detailed descriptions thereof will be omitted where appropriate.

[0067] In the heater section 30B, the density of the heating elements 34 is lower in the central region CA than in the peripheral region PA. Specifically, as shown in the plan view of FIG. 16 , the heater wire pattern constituting the heating elements 34 is formed in a single stroke so that it is denser in the peripheral region PA and sparser in the central region CA. With this configuration, the peripheral region PA has more areas where the heating elements 34 of the heater section 30B are present, as in the heat transfer layer 9 shown in FIG. 9 , making it easier to heat. Meanwhile, the central region CA has no heating elements 34 of the heater section 30B and only the thermally conductive film 33, forming a heat transfer layer 9 as shown in FIG. 15 . The fewer heating elements 34 make it relatively more difficult to heat, which contributes to uniform heating of the secondary battery cells 1.

[0068] On the other hand, during heat dissipation from the secondary battery cells 1, the presence of the heater unit 30B in the peripheral area PA reduces thermal conductivity and heat dissipation as shown in Fig. 9. In the central area CA, the absence of the heating element 34 of the heater unit 30B improves thermal conductivity and promotes heat dissipation as shown in Fig. 15. As a result, the heat dissipation of the secondary battery cells 1 located in the central area CA, where heat dissipation was previously difficult, is improved, contributing to uniform heat dissipation.

[0069] In the example of the heat transfer layer 9 shown in FIG. 15, the first insulating sheet 61 is omitted in order to improve heat dissipation.

[0070] [Embodiment 3] Furthermore, an open window can be formed in the heater section to improve the thermal conductivity of the heat transfer layer. Such an example is shown in Figure 17 as a power supply device according to embodiment 3. In this figure, the same components as those in embodiment 1 and the like are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0071] The heater section 30C shown in FIG. 17 has multiple opening windows 36 formed in a portion of the central area CA, an area where no heater wire is present. The opening windows 36 are indicated by cross-hatching in the figure for illustrative purposes. The first heat transfer sheet 40 and the second heat transfer sheet 50, which are laminated with the heater section 30C, are extruded and filled into the opening windows 36. As a result, a heat transfer layer 9 is formed as shown in FIG. 15 , further improving thermal conductivity. In particular, in the second embodiment, the film 33 of the heater section 30B is present even in the area where no heater wire is present, forming an interface between the first heater surface 31 and the second heater surface 32 of the heater section 30C, thereby reducing thermal conductivity. However, in the power supply device according to the third embodiment, by forming openings in the heater section 30C, the number of interfaces is reduced, thereby improving thermal conductivity.

[0072] While the above examples have been described using stationary power supply devices, the present disclosure is not limited to such applications. The power supply device can also be used for other purposes, such as attaching it to an electrical device to be driven and supplying power to the electrical device. Examples of electrical devices include mobile objects such as electric vehicles and electric carts, as well as portable electrical devices. In such electrical devices, when the remaining capacity of the power supply device becomes low or when the power supply device deteriorates over time, the power supply device can be replaced to continue using the electrical device. However, the present disclosure is not limited to replaceable power supply devices that primarily house secondary battery cells, but can also be applied to configurations in which secondary battery cells are housed within the housing of the electrical device. In the present disclosure, a power supply device that houses secondary battery cells in a case is sufficient, and also includes power supply devices that incorporate secondary battery cells for driving the electrical device within the housing itself. In other words, the present disclosure is not limited to replaceable power supply devices, but can also be applied to electrical devices that incorporate secondary battery cells.

[0073] The power supply device according to the present invention can be suitably used as a backup power source for servers, etc., as a power storage device for home, office, factory, etc., or as a driving power source for mobile objects such as electric carts and electric scooters. It can also be used as a power source for radios and as a power source for portable electrical equipment such as electric cleaners and power tools.

[0074] DESCRIPTION OF SYMBOLS 100 Power supply device 1 Secondary battery cell 1A Cell first end surface 1B Cell second end surface 1a Cell ejection mechanism 2 Battery module 3 Circuit board 4 Board holder 5 Battery holder 7 Lead plate 8 Bus bar 9 Heat transfer layer 10 Outer case 10a Case first surface 10b Case second surface 10c Case third surface 10d Case fourth surface 10e Case fifth surface 10f Case sixth surface 11 Main body case 12 Bottom case 13 Front panel 14 Storage space 15 Gas exhaust port 20 Metal plate 30, 30B, 30C Heater section 31 Heater first surface 32 Heater second surface 33 Film 34 Heat generating element 36 Opening window 40 First heat transfer sheet 50 Second heat transfer sheet 61 First insulating sheet 62 Second insulating sheet 70 Cooling plate CA Central area PA Peripheral area

Claims

1. A power supply device comprising: a plurality of secondary battery cells, each having a cell first end face and a cell second end face, and arranged in a position where the cell first end faces are flush with each other; a heater section that is planar and has a heater first surface and a heater second surface, and is arranged in a position where the heater first surface faces the cell first end faces of the plurality of secondary battery cells; a first heat transfer sheet having thermal conductivity and interposed between the cell first end faces of the plurality of secondary battery cells and the heater first surface; a second heat transfer sheet having thermal conductivity and arranged on the heater second surface side; and an exterior case having a case first surface that defines a storage space to store the plurality of secondary battery cells, the first heat transfer sheet, the heater section, and the second heat transfer sheet.

2. A power supply device as claimed in claim 1, wherein the exterior case has an opening on at least the first case face, and the exterior case includes a thermally conductive bottom case that closes the opening on the first case face and faces the second heat transfer sheet in the storage space.

3. A power supply device according to claim 2, further comprising a cooling plate connected in thermal contact with the outer surface of said bottom case.

4. A power supply device as claimed in claim 2, further comprising: a first insulating sheet interposed between said heater section and said first heat transfer sheet; and a second insulating sheet interposed between said second heat transfer sheet and said bottom case.

5. A power supply device as claimed in claim 1, wherein the heater section has a heating element arranged within a plane, and the density of the heating element in the heater section is lower in a central region than in surrounding regions.

6. A power supply device as claimed in claim 5, wherein the heater section has a central area where the density of the heating element is low, the central area being partially opened.

7. A power supply device according to any one of claims 1 to 6, wherein each of the plurality of secondary battery cells has a positive electrode on the second end face of the cell, the second end faces of the cells are connected to each other by a lead plate, and no lead plate is provided on the first end face side of the cell.

Images