Power supply device

Abstract

This power supply device reduces a heat quantity by reducing an electric resistance value. A power supply device 100 comprises: a plurality of secondary battery cells 1 each having positive and negative cell electrodes exposed on one cell end surface 1a; and a plurality of lead elements 20 each connected to the one cell end surface 1a of the corresponding secondary battery cell 1 so that the secondary battery cells 1 are electrically connected to each other. Each lead element 20 includes a first lead piece 31, a second lead piece 32 formed at a height different from that of the first lead piece 31 in the thickness direction of the lead element 20, and a third lead piece 33 interposed between the first lead piece 31 and the second lead piece 32. The third lead piece 33 is formed thicker than the first lead piece 31 and the second lead piece 32. Each lead element 20 is configured such that the first lead piece 31 and the second lead piece 32 are connected to different potentials.

Description

power supply

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

[0002] Power supply devices in which rechargeable secondary battery cells such as lithium-ion secondary batteries are housed in a battery holder and the cell end faces of each secondary battery cell are connected by lead plates are used in a wide range of applications, including as a power source for driving electrically-powered mobile objects such as vehicles and construction machinery, and for driving electrical equipment such as power tools. When using a large number of cylindrical secondary battery cells in such power supply devices, in addition to a configuration in which lead plates are welded to the upper and lower cell end faces of the secondary battery cells for electrical connection, a structure known as one-sided current collection, in which positive and negative cell electrodes are connected at one cell end face, has also been proposed (see, for example, Patent Document 1).

[0003] However, in the battery module 600 of Patent Document 1, as shown in Fig. 6, thin lead plates 605 are branched thinly to connect to the positive and negative cell electrodes at one cell end face of each secondary battery cell 601. There is a problem in that such thin lead plates 605 are unable to exhibit sufficient heat dissipation performance.

[0004] On the other hand, in order to improve heat dissipation, a configuration in which lead plates 705 are fixed to the upper and lower cell end faces of a secondary battery cell 701, as in the power supply device 700 according to the comparative example shown in Fig. 7 , and current collector plates 706 are overlapped and welded to each lead plate 705, is conceivable. However, with this configuration, as shown in Fig. 8 , current concentrates on the lead plate 705 that has the shortest path, resulting in almost no current flowing through the current collector plate 706. This does not contribute to reducing electrical resistance, and there is a problem in that heat is generated unevenly in the area.

[0005] US Patent No. 10707471B2

[0006] One object of one embodiment of the present disclosure is to provide a power supply device with improved heat dissipation performance of secondary battery cells. Another object of another embodiment is to provide a power supply device with reduced electrical resistance and reduced heat generation. Note that the description of these objects and problems of the present disclosure does not preclude the existence of other objects and problems. Furthermore, it is not necessary for one embodiment of the present disclosure to solve all of these problems. Furthermore, problems other than these 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 is a power supply device comprising a plurality of secondary battery cells, each having a positive and negative cell electrode on one of its cell end faces, and a plurality of lead bodies connected to the one of the cell end faces of each secondary battery cell to electrically connect the secondary battery cells to each other, wherein each lead body includes a first lead piece, a second lead piece formed at a different height than the first lead piece in the thickness direction of the lead body, and a third lead piece interposed between the first lead piece and the second lead piece, wherein the third lead piece is formed thicker than the first lead piece and the second lead piece, and each lead body is configured to connect the first lead piece and the second lead piece to different potentials.

[0008] A power supply device according to another embodiment of the present disclosure is a power supply device comprising a plurality of secondary battery cells, each having a positive and negative cell electrode exposed on one of its cell end faces, a plurality of lead bodies connected to the one of the cell end faces of each secondary battery cell and electrically connecting the secondary battery cells to each other, a circuit board electrically connected to the plurality of secondary battery cells, and wiring leads connecting the circuit board and the lead bodies, wherein the thickness of the lead bodies is formed to be thicker than the wiring leads, and the direction of current flow when current is passed through the lead bodies is along the thickness direction of the lead bodies.

[0009] According to the power supply device of one embodiment of the present disclosure, by conducting current through the first and second reed pieces stacked at different heights, current flows in the thickness direction of the lead body, and the increased thickness of the lead body reduces the electrical resistance value and suppresses the amount of heat generated.Furthermore, by separating the first and second reed pieces and increasing the thickness of the lead body, the battery resistance value of the lead body can be reduced.

[0010] In addition, in the power supply device according to another aspect of the present disclosure, the electrical resistance can be reduced by increasing the thickness of the lead body, thereby suppressing the amount of heat generated. Furthermore, by passing current through the lead body in the thickness direction, the electrical resistance can be reliably reduced.

[0011] FIG. 10 is a perspective view showing a power supply device according to an embodiment. FIG. 11 is a perspective view showing a state in which a circuit board has been removed from the power supply device of FIG. 1. FIG. 2 is a perspective view of the power supply device of FIG. 2 omitting the battery holder. FIG. 3 is a schematic cross-sectional view of the power supply device of FIG. 3 taken along lines IVA-IVA and IVB-IVB. FIG. 4 is a circuit diagram showing a connection state of secondary battery cells. FIG. 4 is an enlarged plan view showing a conventional battery module. FIG. 4 is an enlarged perspective view showing a power supply device according to a comparative example. FIG. 7 is a perspective cross-sectional view of the power supply device according to an embodiment. FIG.

[0012] The embodiments of the present disclosure may be specified by the following configurations and features.

[0013] In a power supply device according to another aspect of the present disclosure, in the above-described aspect, the first lead piece is connected to a first cell electrode of a first secondary battery cell that is closest to a lead body to which the first lead piece belongs, and the second lead piece is connected to a second cell electrode, different from the first cell electrode, of a second secondary battery cell that is closest to a lead body to which the second lead piece belongs and is electrically connected to the first secondary battery cell via the lead body. With the above configuration, the first lead piece and the second lead pieces stacked at different heights are electrically connected to the first secondary battery cell and the second secondary battery cell, respectively. When current is passed between the first secondary battery cell and the second secondary battery cell via the lead body, current is passed in the thickness direction of the lead body, thereby reducing the electrical resistance of the lead body and suppressing the amount of heat generation.

[0014] In a power supply device according to another aspect of the present disclosure, in any of the above aspects, the first cell electrode and the second cell electrode are arranged on the same plane, and the first lead piece is arranged at a higher position than the second lead piece. With this configuration, the first lead piece stacked at a higher position and the second lead piece stacked at a lower position are electrically connected to the first secondary battery cell and the second secondary battery cell, respectively. By passing current between the first secondary battery cell and the second secondary battery cell via the lead body, the current is passed in the thickness direction of the lead body, thereby reducing the electrical resistance of the lead body and suppressing the amount of heat generated.

[0015] In a power supply device according to another aspect of the present disclosure, in any of the above aspects, the first reed piece is disposed on the upper surface of the lead body, and the second reed piece is disposed on the lower surface of the lead body. With this configuration, by passing current between the first reed piece and the second reed piece disposed on the upper and lower surfaces of the lead body, respectively, the current path is in the thickness direction of the lead body, thereby reducing the electrical resistance value during current flow.

[0016] In yet another aspect of the power supply device according to the present disclosure, in any of the above aspects, the first lead piece has a first current collecting tab drawn out from an edge of the first lead piece for connection to the first cell electrode of the first secondary battery cell, and the second lead piece has a second current collecting tab drawn out from an edge of the second lead piece for connection to the second cell electrode of the second secondary battery cell. With the above configuration, the first lead piece and the second lead piece, which are arranged at different heights, can be connected to the first cell electrode of the first secondary battery cell and the second cell electrode of the second secondary battery cell, which are arranged on the same plane, respectively.

[0017] In a power supply device according to still another aspect of the present disclosure, in any of the above aspects, the lead body includes a main body portion that extends in one direction in a plan view, and the first current collecting tab and the second current collecting tab each extend from either side surface of the main body in the extension direction in a direction intersecting the extension direction. With the above configuration, the first current collecting tab and the second current collecting tab each extend from either side surface of the lead body in the extension direction, thereby making it possible to electrically connect the cell electrodes of adjacent secondary battery cells.

[0018] Furthermore, in a power supply device according to another aspect of the present disclosure, in any of the above aspects, each lead body is a laminated body in which the first reed piece, the second reed piece, and the third reed piece are stacked.

[0019] Furthermore, in the power supply device according to any one of the above aspects, the third reed piece is a laminate of a plurality of reed pieces.

[0020] Furthermore, in a power supply device according to another aspect of the present disclosure, in any of the above aspects, each lead body is formed integrally with the first reed piece, the second reed piece, and the third reed piece.

[0021] In yet another aspect of the power supply device according to the present disclosure, in any of the above aspects, the plurality of lead bodies include a second lead body, the second lead body being a laminate of a plurality of lead pieces including a first lead piece, the first lead piece being connected to a cell electrode of a secondary battery cell among the plurality of secondary battery cells that is adjacent to the lead body to which the first lead piece belongs, and the side of the second lead body opposite to the side on which the first lead piece is provided serves as an output extraction surface. With the above configuration, the second lead body has an output extraction surface on the side opposite to the first lead piece connected to the secondary battery cell, and by similarly passing electricity through the second lead body in the thickness direction, the electrical resistance of the second lead body can be reduced and the amount of heat generated can be suppressed.

[0022] Furthermore, in a power supply device according to another aspect of the present disclosure, in any of the above aspects, the secondary battery cell has a cylindrical outer can that defines its outer shape, the one cell end face is one end face of the cylindrical shape, and one or the other of the positive and negative cell electrodes is arranged in a central region and a circumferential region of the one cell end face, respectively.

[0023] Furthermore, a power supply device according to another embodiment of the present disclosure, in any of the above embodiments, further includes a battery holder that holds the plurality of secondary battery cells, and a window portion is opened in an end face of the battery holder to expose one of the cell end faces of the secondary battery cells, and the one of the cell end faces exposed through the window portion is electrically connected to each other by the lead body.

[0024] 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 served by a single component, or conversely, the functions of a single component may be shared by multiple components.

[0025] The power supply device of the present disclosure can be used as a power source for portable electrical devices such as power tools and electric cleaners, as a driving power source for mobile objects such as electric carts, electric scooters, and assisted bicycles, as a backup power source for servers in stationary power storage applications, as a power supply device for home, office, and factory use, and as a driving power source for vehicles such as hybrid cars and electric automobiles. Hereinafter, a power supply device used as a driving power source for power tools will be described as one embodiment of the present invention. [Embodiment 1]

[0026] 1 to 5 show a power supply device 100 according to a first embodiment of the present disclosure. In these figures, FIG. 1 is a perspective view of the power supply device 100 according to the embodiment, FIG. 2 is a perspective view of the power supply device 100 of FIG. 1 with the circuit board 3 removed, FIG. 3 is a perspective view of the power supply device 100 of FIG. 2 without the battery holder 10, FIG. 4 is a schematic cross-sectional view of the power supply device 100 of FIG. 3 taken along lines IVA-IVA and IVB-IVB, and FIG. 5 is a circuit diagram showing the connection state of secondary battery cells 1. As shown in FIG. 1, the power supply device 100 includes a battery module 2 and a circuit board 3. The battery module 2 is composed of a battery holder 10, multiple secondary battery cells 1 held in the battery holder 10, and lead bodies 20 connecting the multiple secondary battery cells 1. The battery module 2 and the circuit board 3 are connected by wiring leads 5. (Battery Module 2)

[0027] The battery module 2, also called a core pack, holds multiple secondary battery cells 1. The battery module 2 may also be composed of multiple sub-modules, each housing multiple secondary battery cells 1. A circuit board 3 is mounted around the battery module 2. In the example of FIG. 1, the circuit board 3 is disposed on the main surface of the battery module 2, but the circuit board may also be disposed in another position, for example, on the top or side of the battery module. (Battery holder 10)

[0028] The battery module 2 includes a battery holder 10, secondary battery cells 1, and lead bodies 20. As shown in FIG. 4, the battery holder 10 has multiple cylindrical holder sections 11, into which secondary battery cells 1 are inserted and held. The battery holder 10 can accommodate all of the secondary battery cells 1 as a whole, or it can be divided into multiple sub-holders, with some of the multiple secondary battery cells accommodated in each sub-holder. The battery holder can also be divided in the length direction of the secondary battery cells. The battery holder 10 is made of a material with excellent insulating properties. Preferably, it is made of a resin such as polycarbonate or PC-ABS alloy.

[0029] As shown in Figures 1 and 4, the battery holder 10 has an end face with a window 12 that exposes one cell end face 1a of the secondary battery cells 1. The cell end faces 1a exposed through the window 12 are electrically connected to each other by a lead body 20. (Secondary battery cells 1)

[0030] The battery holder 10 holds multiple rechargeable battery cells 1. Each rechargeable battery cell 1 can be cylindrical or rectangular. In the example shown in FIGS. 1 to 4, cylindrical rechargeable battery cells 1 are arranged vertically in a staggered pattern. The number and arrangement of the rechargeable battery cells 1 are not limited to this example, and any number and arrangement can be used as appropriate. For example, cylindrical rechargeable battery cells can be arranged in a matrix. Known rechargeable batteries, such as lithium-ion rechargeable batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, can be used as the rechargeable battery cells 1.

[0031] Each secondary battery cell 1 has a positive and a negative cell electrode. The terminal of the positive or negative cell electrode is preferably provided on one cell end surface 1a of the secondary battery cell 1. That is, each secondary battery cell 1 has a positive and a negative cell electrode exposed on one cell end surface 1a. In the example shown in FIG. 1 , a positive terminal 1b is provided on one cell end surface 1a of the secondary battery cell 1, and the other surface of the outer can serves as a negative electrode. As a result, on the cell end surface 1a on the upper surface of the secondary battery cell 1, the positive terminal 1b is exposed in the center of the circle, and the negative terminal 1c is exposed on the circumferential side.

[0032] 1 and other examples, a lead body 20 is connected to one cell end face 1a of the secondary battery cell 1, and no electrical connection member such as the lead body 20 is disposed on the other cell end face 1a. With this configuration, the other cell end face 1a of each secondary battery cell 1 can be utilized as a heat dissipation area. For example, by disposing a cooling mechanism such as a cooling plate on the bottom side of the battery holder 10 of the power supply device 100 in FIG. 1 and thermally coupling it to each secondary battery cell 1, the secondary battery cells 1 can be individually cooled, thereby increasing cooling capacity.

[0033] The multiple secondary battery cells 1 are connected in series or in parallel via lead bodies 20. The number of series connections or parallel connections can be set as desired according to the required specifications. In the example shown in FIG. 1 etc., each lead body 20 connects the cell end faces 1a of four secondary battery cells 1, forming a 2 series x 2 parallel connection as shown in FIG. 5. The number of secondary battery cells 1 and the connection configuration, i.e., the number of series connections or the number of parallel connections, are not limited to this configuration. (Circuit board 3)

[0034] The battery module 2 is connected to a circuit board 3 via wiring leads 5. The circuit board 3 is equipped with a charge / discharge circuit that charges and discharges the secondary battery cells 1, and a protection circuit that monitors the voltage and temperature of the secondary battery cells 1 and cuts off the current in the event of an abnormality. The circuit board 3 is made of a glass epoxy board or the like. A board holder may also be provided as a member to hold the circuit board 3.

[0035] 1 and other examples show an example in which one circuit board 3 is mounted on one surface of each battery block 30, but the present disclosure is not limited to this configuration, and the battery block 30 may be divided into multiple circuit boards. (Wiring leads 5)

[0036] The wiring leads 5 are components for connecting the battery module 2 to the circuit board 3. Here, a portion of the lead body 20 electrically connected to the secondary battery cell 1 is electrically connected to the circuit board 3. In the example of FIG. 1, the wiring leads 5 are arranged on the outer surface of the battery holder 10. The wiring leads 5 are made of a metal plate with excellent conductivity, such as an aluminum plate, a nickel plate, or a copper plate. The thickness of the wiring leads 5 is preferably in the range of 0.10 mm to 4.00 mm, and can be changed depending on the current value used. The wiring leads 5 may also be made of a metal wire with excellent conductivity, such as an aluminum wire, a nickel wire, or a copper wire. (Lead body 20)

[0037] The multiple secondary battery cells 1 are electrically connected by multiple lead bodies 20. A lead body 20 is connected to one cell end surface 1a of each secondary battery cell 1. The lead body 20 is formed thicker than lead plates for electrical connection other than the lead body 20. Examples of lead plates for electrical connection other than the lead body 20 include wiring leads 5 for connection to a circuit board 3. Furthermore, the direction of current flow when electricity is passed through the lead body 20 is aligned along the thickness direction of the lead body 20. Increasing the thickness of the lead body 20 in this way reduces electrical resistance and suppresses heat generation. Furthermore, passing current through the increased thickness of the lead body 20 in the thickness direction reliably reduces electrical resistance.

[0038] In a conventional battery module 600, as shown in Figure 6, a thin lead plate 605 is branched at one end of each secondary battery cell 601 to connect to the positive and negative cell electrodes. However, such a thin lead plate 605 has the problem of being unable to provide sufficient heat dissipation performance. Furthermore, a thin lead plate 605 has a high resistance value, which generates Joule heat according to the resistance value.

[0039] In addition, there was the problem of the current value itself becoming higher. When current is passed through the lead plates, Joule heat is generated in proportion to the square of the current value. In particular, in order to meet the demand for higher output and capacity in power supply devices in recent years, the performance of the secondary battery cells themselves has improved, and the current value tends to become larger. This also increases the amount of heat generated, making it necessary to take appropriate heat dissipation measures.

[0040] On the other hand, in order to improve heat dissipation, a configuration in which lead plates 705 are fixed to the upper and lower cell end faces of a secondary battery cell 701, as in the power supply device 700 according to the comparative example shown in Figure 7, can be considered in which current collecting plates 706 are overlapped and welded to each lead plate 705.

[0041] 8, this configuration has the problem that current concentrates on the lead plate 705, which is the shortest path for current flow, and as a result, almost no current flows to the stacked current collector plate 706. This does not contribute to reducing the electrical resistance, i.e., the amount of heat generated, and causes a problem of uneven heat generation.

[0042] In contrast, in the power supply device 100 according to this embodiment, the lead bodies 20 connected to the cell end faces 1a of each secondary battery cell 1 are made thicker than the lead plates for other electrical connections, such as the wiring leads 5, and are configured so that the direction of current flow through the lead bodies 20 is the thickness direction of the lead bodies 20. In addition to increasing the thickness of the lead bodies 20 in this way, restricting the direction of current flow to the thickness direction reliably reduces the electrical resistance value during current flow, suppressing the amount of heat generated, and, combined with the improved heat dissipation performance due to the increased heat capacity of the thicker lead bodies 20, realizing heat dissipation control (intermediate lead body 21; second lead body 22).

[0043] The example shown in Figures 1 to 3 uses four lead bodies 20 with different shapes. As shown in the circuit diagram of Figure 5, the four lead bodies 20 connect four secondary battery cells 1 in a 2-series x 2-parallel configuration. In Figure 5, the connection areas of the secondary battery cells 1 are indicated by A, B, and C. The largest of the four lead bodies 20, the lead body 20 located in the middle, is called the intermediate lead body 21. This intermediate lead body 21 covers connection area B in Figure 5. The remaining lead bodies 20 covering connection areas A and C are called second lead bodies 22. In Figure 1 and other figures, the right-side second lead body 22a covers connection area A. The upper second lead body 22b and the left-side second lead body 22c cover connection area C. The second lead bodies 22a and 22c covering connection areas A and C serve as terminals for extracting the total output. The intermediate lead body 21 covering connection area B is connected to the circuit board via wiring leads 5 to detect the intermediate potential. (Lead pieces 30)

[0044] Each lead body 20 is preferably made up of a laminate of multiple lead pieces 30. Like the wiring leads 5, each lead piece 30 is made up of a metal plate with excellent conductivity, such as an aluminum plate, a nickel plate, or a copper plate. The thickness of each lead piece 30 is preferably 0.10 mm to 3.00 mm, and can be changed depending on the current value used. (First lead piece 31; second lead piece 32)

[0045] The multiple reed pieces 30 include a first reed piece 31 and a second reed piece 32 that is a different height from the first reed piece 31. Each lead body 20 is configured so that the first reed piece 31 and the second reed piece 32 are connected to different potentials. With this configuration, by passing electricity through the first reed piece 31 and the second reed piece 32 that are stacked at different heights, electricity is passed through the thickness direction of the lead body 20, and the increased thickness of the lead body 20 reduces the electrical resistance value, thereby suppressing the amount of heat generated. (Intermediate lead body 21)

[0046] In the schematic cross-sectional view of FIG. 3 , of the three lead bodies 20, the middle lead body 20 is designated as the intermediate lead body 21, and the left and right lead bodies 20 are designated as the second lead bodies 22. Furthermore, among the rechargeable battery cells 1, the left one is designated as the first rechargeable battery cell 1A, and the right one is designated as the second rechargeable battery cell 1B. The intermediate lead body 21 connects the first lead piece 31 to the first cell electrode of the first rechargeable battery cell 1A. It also connects the second lead piece 32 to the second cell electrode of the second rechargeable battery cell 1B. The first rechargeable battery cell 1A and the second rechargeable battery cell 1B are held by the battery holder 10 so that their cell end faces 1a are flush with each other. As a result, the first cell electrode of the first rechargeable battery cell 1A and the second cell electrode of the second rechargeable battery cell 1B are also flush with each other. The first lead piece 31 is positioned higher than the second lead piece 32. This arrangement electrically connects the first lead piece 31 stacked at a higher position and the second lead piece 32 stacked at a lower position to the first secondary battery cell 1A and the second secondary battery cell 1B, respectively. When electricity is passed between the first secondary battery cell 1A and the second secondary battery cell 1B via the lead body 20, electricity is passed in the thickness direction of the lead body 20, reducing the electrical resistance of the lead body 20 and suppressing the amount of heat generated (third lead piece 33).

[0047] The lead body 20 includes a third lead piece 33 interposed between the first reed piece 31 and the second reed piece 32. By separating the first reed piece 31 and the second reed piece 32 through the third reed piece 33, the thickness of the lead body 20 can be increased, thereby reducing the battery resistance of the lead body 20. The third reed piece 33 is a laminate of multiple reed pieces 30, as shown in FIG. 4 and other figures. By stacking lead pieces 30 of the same shape, a thicker lead body 20 can be easily formed. The third reed piece 33 is preferably made of the same material and thickness as the first reed piece 31 and the second reed piece 32. The material, thickness, and number of layers of the reed pieces 30 constituting the third reed piece 33 are appropriately adjusted depending on the electrical resistance of the material of the reed pieces 30, the expected rated current, allowable heat generation, allowable size, and other specifications. In situations where a larger current is to be applied, the number of layers can be increased to thicken the lead body 20, thereby reducing electrical resistance and improving heat dissipation.

[0048] The lead body 20 is formed by stacking a plurality of such lead pieces 30, and the lead pieces 30 are joined together. The lead pieces 30 can be joined by any known method, such as laser welding, spot welding, welding using ultrasonic vibration, or mechanical pressing or fastening, such as punching, clamping, or caulking. [Embodiment 2]

[0049] However, the third reed piece 33 may be formed thicker than the first reed piece 31 and the second reed piece 32. Such an example is shown in the cross-sectional view of Figure 9 as a power supply device 200 according to the second embodiment. In this figure, the same components as those in the first embodiment described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0050] In the power supply device 200 of Figure 9, each lead body 20B has a three-layer structure in which a first reed piece 31, a third reed piece 33B, and a second reed piece 32 are laminated. The third reed piece 33B is a thick metal plate, and by reducing the number of layers, the contact resistance at the joint interface between the reed pieces 30B is reduced, and the fixation of the reed pieces 30B can be simplified. [Embodiment 3]

[0051] In the above example, each lead body 20, 20B is configured as a laminated body formed by stacking multiple lead pieces. However, the present disclosure is not limited to a configuration in which the lead body is a laminated body, and it can also be configured as an integrated body. Such an example is shown in the cross-sectional view of Figure 10 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 description thereof will be omitted as appropriate.

[0052] In the power supply device 300 shown in Figure 10, each lead body 20C is formed integrally with a first reed piece 31C, a third reed piece 33C, and a second reed piece 32C. A first current collecting tab 41C and a second current collecting tab 42C extend from the first reed piece 31C and the second reed piece 32C, respectively. Such a lead body 20C can be formed by casting or other methods. It also includes a configuration in which the first reed piece 31C, the third reed piece 33C, and the second reed piece 32C, which were originally separate members, are thermocompression bonded, welded, or other methods to make the interlayers at the interface between the lead pieces invisible. Using an integrally formed lead body 20C in this manner similarly provides the advantage of reducing the contact resistance at the interface between the lead pieces.

[0053] As described above, to ensure that the direction of current flow through the lead body 20 is along the thickness direction of the lead body 20, electrical connections are made at both ends of the lead body 20 in the thickness direction. In the cross-sectional view of FIG. 4, the upper and lower sides are used for upstream and downstream electrical connections during current flow, respectively. The intermediate lead body 21 shown in the center of the figure shows how its top surface is connected to the positive electrode terminal 1b of the secondary battery cell 1 and its bottom surface is connected to the negative electrode terminal 1c of the secondary battery cell 1. As a result, current flows from top to bottom in the thickness direction of the lead body 20 when the secondary battery cell 1 is discharged. Meanwhile, current flows in the opposite direction, that is, from bottom to top in the thickness direction, during charging. In this way, by electrically connecting the lead body 20 to the outside at different heights, current is controlled to flow in the thickness direction. In other words, different poles are not connected on the same surface or at the same height of the lead body 20.

[0054] On the other hand, in a configuration in which multiple secondary battery cells 1 are connected in parallel with one lead body 20, it is possible to connect the same poles on the same surface or at the same height of the lead body 20. In the example shown in FIGS. 1 to 3, the first lead piece 31 on the top surface of the intermediate lead body 21 is connected to the positive electrodes of two first secondary battery cells 1A, and the second lead piece 32 on the bottom surface is connected to the negative electrodes of two second secondary battery cells 1B. In other words, the first lead piece 31 and the second lead piece 32 are each connected to multiple cell electrodes that are assumed to be at the same potential. This allows for parallel connection while also allowing current to flow in the thickness direction of the intermediate lead body 21. (First current collecting tab 41; second current collecting tab 42)

[0055] Each lead body 20 also has a current collecting tab for connecting to a cell electrode on the cell end surface 1a of the secondary battery cell 1. Specifically, as shown in Figures 1 to 4, the first lead piece 31 has a first current collecting tab 41 drawn out from the edge of the first lead piece 31 to connect to the first cell electrode of the first secondary battery cell 1A. The second lead piece 32 has a second current collecting tab 42 drawn out from the edge of the second lead piece 32 to connect to the second cell electrode of the second secondary battery cell 1B. This configuration makes it possible to connect the first lead piece 31 and the second lead piece 32, which are arranged at different heights, to the first cell electrode of the first secondary battery cell 1A and the second cell electrode of the second secondary battery cell 1B, which are arranged on the same plane, respectively.

[0056] The lead body 20 also includes a main body 40 that extends in one direction in a plan view. Current collecting tabs such as the first current collecting tab 41 and the second current collecting tab 42 each extend from either side surface of the main body 40 in the extension direction in a direction intersecting the extension direction. This allows the first current collecting tab 41 and the second current collecting tab 42 to extend from either side surface of the lead body 20 in the extension direction, thereby electrically connecting the cell electrodes of adjacent secondary battery cells 1.

[0057] Each current collecting tab is bent in the middle and protrudes diagonally downward, absorbing any slight misalignment and enabling adjustment of the fixed position and height relative to the cell electrode. In the example shown in Figures 1 to 4, the area exposed to the negative electrode at the cell end face 1a, particularly the width, is narrower than that of the positive electrode. Therefore, the second current collecting tab 42 connected to the negative electrode side is accordingly formed small. The first current collecting tab 41 connected to the positive electrode side is also formed larger. In particular, the tip of the first current collecting tab 41 has a large area to facilitate fastening to the positive electrode terminal 1b by welding or other means. Here, the tip of the first current collecting tab 41 is rectangular, but it may also be circular. Furthermore, it may be branched or otherwise modified into any shape suitable for fastening. Furthermore, the thickness of the first current collecting tab 41 and the second current collecting tab 42 is formed thinner than that of the intermediate lead body 21, which forms the main body of the lead body 22. (Second lead body 22)

[0058] The intermediate lead body 21 described above includes a first current collecting tab 41 and a second current collecting tab 42. In other words, it includes both a first reed piece 31 including the first current collecting tab 41 and a second reed piece 32 including the second current collecting tab 42. On the other hand, the second lead body 22 does not necessarily have to include both the first current collecting tab 41 and the second current collecting tab 42. That is, it is sufficient to include either the first reed piece 31 including the first current collecting tab 41 or the second reed piece 32 including the second current collecting tab 42. For example, in FIGS. 1 to 3 , the second lead body 22 covering the connection area A shown on the right side of the second lead body 22 includes the first reed piece 31 including the first current collecting tab 41 but does not include the second reed piece 32 including the second current collecting tab 42. Instead of the second current collecting tab 42, the side of the second lead body 22 opposite the side where the first reed piece 31 is provided, i.e., the bottom surface in this case, serves as the output extraction surface 44. Thus, by passing a current through the second lead body 22 in the thickness direction, the electrical resistance of the second lead body 22 can be reduced, thereby suppressing the amount of heat generated.

[0059] 1 to 3, the second lead bodies 22 that carry the connection region C shown on the left and upper sides include the second lead piece 32 with the second current collecting tab 42, but do not include the first lead piece 31 with the first current collecting tab 41. Instead of the first current collecting tab 41, the side of the second lead body 22 opposite to the side on which the second lead piece 32 is provided, in this case the top surface, serves as the output extraction surface 44. This allows current to be passed through the second lead body 22 in the thickness direction in the same way, thereby reducing the electrical resistance of the second lead body 22 and suppressing the amount of heat generation.

[0060] In the above examples, the power supply device is attached to the electrical equipment to be driven and supplies power to the electrical equipment. 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 equipment. However, the present invention is not limited to replaceable power supply devices that mainly house secondary battery cells, but can also be applied to configurations in which secondary battery cells are housed within the housing of the electrical equipment. In this disclosure, a power supply device is sufficient as long as it houses secondary battery cells in a case, and also includes power supply devices that incorporate secondary battery cells for driving the electrical equipment within the housing of the electrical equipment itself. In other words, the present invention is not limited to replaceable power supply devices, but can also be applied to electrical equipment that incorporates secondary battery cells.

[0061] The power supply device according to the present disclosure can be suitably used as a driving power source for assisted bicycles, self-propelled delivery robots, electric carts for delivery and golf courses, electric scooters, construction machinery, hybrid cars, electric vehicles, etc. It can also be used as a power source for portable electrical equipment such as radios, electric cleaners, and power tools. Alternatively, it can be used as a stationary power storage device, for example, a power supply device for home, business, or factory use, or as a backup power source for servers, etc.

[0062] DESCRIPTION OF SYMBOLS 100, 200, 300... Power supply device 1... Secondary battery cell; 1A... First secondary battery cell; 2B... Second secondary battery cell 1a... Cell end surface; 1b... Positive terminal; 1c... Negative terminal 2... Battery module 3... Circuit board 5... Wiring lead 10... Battery holder 11... Holder cylindrical portion 12... Window portion 20, 20B, 20C... Lead body 21... Intermediate lead body 22... Second lead body; 22a... Right-side second lead body; 22b... Second lead body; 22c... Left-side second lead body 30, 30B... Lead piece 31, 31C... First lead piece 32, 32C... Second lead piece 33, 33B, 33C... Third lead piece 40... Main body portion 41, 41C... First current collecting tab 42, 42C... Second current collecting tab 44... Output extraction surface 600... Battery module 601... Secondary battery cell 605... Lead plate 700... Power supply device 701... Secondary battery cell 705... Lead plate 706... Current collector plate A, B, C... Connection area

Claims

1. A power supply device comprising: a plurality of secondary battery cells, each having a positive and negative cell electrode on one cell end face; and a plurality of lead bodies connected to one of the cell end faces of each secondary battery cell to electrically connect the secondary battery cells to each other, wherein each lead body includes: a first lead piece; a second lead piece formed at a different height than the first lead piece in the thickness direction of the lead body; and a third lead piece interposed between the first lead piece and the second lead piece, wherein the third lead piece is formed to be thicker than the first lead piece and the second lead piece, and wherein each lead body is configured to connect the first lead piece and the second lead piece to different potentials.

2. A power supply device as claimed in claim 1, wherein the first lead piece is connected to a first cell electrode of a first secondary battery cell among the plurality of secondary battery cells that is adjacent to the lead body to which the first lead piece belongs, and the second lead piece is connected to a second cell electrode, different from the first cell electrode, of a second secondary battery cell among the plurality of secondary battery cells that is adjacent to the lead body to which the second lead piece belongs and is electrically connected to the first secondary battery cell via the lead body.

3. A power supply device according to claim 2, wherein the first cell electrode and the second cell electrode are arranged on the same plane, and the first lead piece is arranged at a higher position than the second lead piece.

4. A power supply device according to claim 3, wherein the first reed piece is arranged on the upper surface of the lead body, and the second reed piece is arranged on the lower surface of the lead body.

5. A power supply device as claimed in claim 2, wherein the first lead piece has a first current collecting tab drawn out from an edge of the first lead piece for connection to the first cell electrode of the first secondary battery cell, and the second lead piece has a second current collecting tab drawn out from an edge of the second lead piece for connection to the second cell electrode of the second secondary battery cell.

6. A power supply device as claimed in claim 5, wherein the lead body has a main body portion that extends in one direction in a plan view, and the first current collecting tab and the second current collecting tab each extend from either side of the main body portion in the extension direction in a direction that intersects with the extension direction.

7. A power supply device according to any one of claims 1 to 6, wherein each lead body is a laminated body in which the first reed piece, the second reed piece, and the third reed piece are laminated together.

8. A power supply device according to any one of claims 1 to 6, wherein the third reed piece is a laminate of a plurality of reed pieces.

9. A power supply device according to any one of claims 1 to 6, wherein each lead body is formed by integrally forming the first reed piece, the second reed piece, and the third reed piece.

10. A power supply device according to any one of claims 1 to 6, wherein the plurality of lead bodies include a second lead body, the second lead body being a laminate of a plurality of lead pieces including the first lead piece, the first lead piece being connected to the cell electrode of a secondary battery cell among the plurality of secondary battery cells that is adjacent to the lead body to which the first lead piece belongs, and the side of the second lead body opposite to the side on which the first lead piece is provided serves as an output extraction surface.

11. A power supply device according to any one of claims 1 to 6, wherein the secondary battery cell has a cylindrical exterior can that defines its outer shape, the one cell end face is one end face of the cylinder, and one or the other of the positive and negative cell electrodes is arranged in the central region and the circumferential region of the one cell end face, respectively.

12. A power supply device according to any one of claims 1 to 6, further comprising a battery holder for holding the plurality of secondary battery cells, wherein an end face of the battery holder has a window opening through which one of the cell end faces of the secondary battery cells is exposed, and wherein the one of the cell end faces exposed through the window is electrically connected to each other by the lead body.

13. A power supply device comprising: a plurality of secondary battery cells, each having a positive and negative cell electrode exposed on one of its cell end faces; a plurality of lead bodies connected to one of the cell end faces of each secondary battery cell and electrically connecting the secondary battery cells to each other; a circuit board electrically connected to the plurality of secondary battery cells; and wiring leads connecting the circuit board and the lead bodies, wherein the thickness of the lead bodies is formed to be thicker than the wiring leads, and when electricity is passed through the lead bodies, the direction of current flow is along the thickness direction of the lead bodies.

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