Power supply device

Abstract

Provided is a power supply device in which the configuration of a lead plate is simplified. A power supply device 100 comprises: a plurality of secondary battery cells 1, each of which has a pair of cell end surfaces 1a and a cell side surface connecting the cell end surfaces 1a, and in which one of the pair of cell electrodes is exposed to one cell end surface 1a; a plurality of lead plates 3 respectively connected to one cell end face 1a of each secondary battery cell 1, the plurality of lead plates 3 electrically connecting the secondary battery cells 1 to each other; and a battery holder 2 for holding the plurality of secondary battery cells 1 and the plurality of lead plates 3. The battery holder 2 is configured by integrally joining an insulating holder insulation part 10 and an conductive holder conduction part 20. The holder conduction part 20 constitutes a portion of electrical connection between the cell end surfaces 1a of the secondary battery cells 1 and the lead plates 3.

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 electrodes are connected at one cell end face, has also been proposed (see, for example, Patent Document 1).

[0003] However, in the battery module 500 of Patent Document 1, as shown in Fig. 5, a thin lead plate 503 has a complex structure in which it branches into thin strips to connect to the positive and negative electrodes at one cell end face of each secondary battery cell 501. This poses a problem in that it is difficult to manufacture lead plates 503 with such a complex structure.

[0004] US Patent No. 10707471B2

[0005] One object of one embodiment of the present disclosure is to provide a power supply device with a simplified lead plate configuration. Another object of another embodiment is to provide a power supply device with a simplified battery holder configuration for holding multiple secondary battery cells. 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.

[0006] A power supply device according to one embodiment of the present disclosure includes a plurality of secondary battery cells, each having a pair of cell end faces and cell side faces connecting the cell end faces, with one of the pair of cell electrodes exposed on one of the cell end faces; a plurality of lead plates connected to the one cell end face of each secondary battery cell and electrically connecting the secondary battery cells; and a battery holder that holds the plurality of secondary battery cells and the plurality of lead plates, wherein the battery holder is formed by integrally joining an insulating holder insulating portion and a conductive holder conductive portion, and the holder conductive portion forms part of the electrical connection between the cell end face of each secondary battery cell and each lead plate.

[0007] According to the power supply device of one embodiment of the present disclosure, by making a portion of the battery holder conductive and having it serve as a portion of the electrical connection of the secondary battery cells, it is possible to simplify the electrical connection using the lead plates.

[0008] Fig. 1A is a plan view showing a power supply device according to embodiment 1, and Fig. 1B is a vertical cross-sectional view. Fig. 2A is a plan view showing a power supply device according to embodiment 2, and Fig. 2B is a vertical cross-sectional view. Fig. 3A is a plan view showing a power supply device according to embodiment 3, and Fig. 3B is a vertical cross-sectional view. Fig. 4A is a plan view showing a power supply device according to embodiment 4, and Fig. 4B is a vertical cross-sectional view. Fig. 1B is an enlarged plan view showing a conventional battery module.

[0009] The embodiments of the present disclosure may be specified by the following configurations and features.

[0010] In a power supply device according to another aspect of the present disclosure, in the above-described aspect, each secondary battery cell has the other cell electrode exposed on the other cell end face, and the holder conductive part is electrically connected to the other cell electrode exposed on the other cell end face of each secondary battery cell. With this configuration, the cell electrode exposed on the other cell end face is used to establish electrical connection with the holder conductive part of the battery holder, simplifying electrical connection using lead plates.

[0011] In a power supply device according to another aspect of the present disclosure, in any of the above aspects, each secondary battery cell has the other cell electrode exposed on the cell side surface, and the holder conductive part is electrically connected to the other cell electrode exposed on the cell side surface of each secondary battery cell. With this configuration, the cell electrodes exposed on the cell side surface are electrically connected by the holder conductive part of the battery holder, simplifying the electrical connection using lead plates.

[0012] In a power supply device according to another aspect of the present disclosure, in any of the above aspects, the battery holder forms a plurality of cylindrical storage sections with one edge open, each of which individually stores a corresponding secondary battery cell, a plurality of the holder conductive sections are provided so that at least a portion of the holder conductive section is exposed on the bottom surface of each cylindrical storage section, and the lead plate is electrically connected to one of the cell electrodes exposed on the cell end surface at the open end of the cylindrical storage section. With this configuration, electrical connection can be simplified by connecting only one of the cell electrodes with the lead plate and electrically connecting the other cell electrode with the holder conductive section of the battery holder.

[0013] In addition, in the power supply device according to another aspect of the present disclosure, in any of the above aspects, each holder conductive portion is formed in an L-shape in cross section. With this configuration, by covering a portion of the cell side surface of the secondary battery cell with the holder conductive portion, heat dissipation is also improved.

[0014] In addition, in the power supply device according to another aspect of the present disclosure, in any of the above aspects, the cell side surfaces of each secondary battery cell are covered with the holder insulating portion. With this configuration, the cell side surfaces of the secondary battery cells are insulated by the holder insulating portion, thereby preventing unintended conduction.

[0015] In a power supply device according to still another aspect of the present disclosure, in any of the above aspects, each holder conductive part is embedded in the holder insulating part so as to straddle the cell end faces of adjacent secondary battery cells. With this configuration, each holder conductive part formed in an L-shape in cross section can electrically connect the cell end faces of multiple secondary battery cells inside the battery holder, simplifying the electrical connection structure.

[0016] In a power supply device according to yet another aspect of the present disclosure, in any of the above aspects, the holder insulating portion exposes the edge of each holder conductive portion and insulates the edge of adjacent holder conductive portions between the adjacent cylindrical storage tubes. This configuration makes it possible to bridge lead plates between adjacent cylindrical storage tubes and establish electrical connection while preventing short circuits of the secondary battery cells.

[0017] In addition, the power supply device according to another aspect of the present disclosure is any of the above-described aspects, further including a conductive adhesive layer that fixes the interface between the cell end face of each secondary battery cell and the holder conductive part in an electrically connected state. With this configuration, the cell end face of the secondary battery cell and the holder conductive part can be reliably fixed in an electrically connected state.

[0018] In addition, in a power supply device according to another aspect of the present disclosure, in any of the above aspects, each holder conductive portion forms the cylindrical storage housing that stores adjacent ones of the plurality of secondary battery cells and connects the adjacent cylindrical storage housings to each other as an integrated structure, the holder conductive portion is embedded in the holder insulating portion, and the open end of each cylindrical storage housing is exposed through the holder insulating portion. With this configuration, the periphery of the cell side of the secondary battery cell is covered with the holder conductive portion, thereby improving heat dissipation.

[0019] In addition, the power supply device according to another aspect of the present disclosure is any of the above-described aspects, further including an insulating holder cover interposed between the lead plate and the open end of the cylindrical housing of the holder conductive part. This configuration makes it possible to prevent an unintentional short circuit between the open end of the cylindrical housing of the holder conductive part and the lead plate.

[0020] In addition, in the power supply device according to any one of the above embodiments, the lead plate has a step corresponding to the thickness of the holder cover. With this configuration, the lead plate can be placed on top of the holder cover.

[0021] In a power supply device according to yet another aspect of the present disclosure, in any of the above aspects, the holder conductive portion embedded in the holder insulating portion has a rear surface of the bottom surface that abuts against the cell end face exposed from the holder insulating portion. With this configuration, the bottom surface of the secondary battery cell is exposed from the battery holder, thereby improving cooling efficiency on the bottom surface side.

[0022] In a power supply device according to still another aspect of the present disclosure, the secondary battery cell is welded to the bottom surface of the holder conductive part in any of the above aspects. This configuration provides the advantage that the bottom surface exposed from the battery holder can be used to easily weld the secondary battery cell to the holder conductive part.

[0023] Furthermore, in a power supply device according to another embodiment of the present disclosure, in any of the above embodiments, the secondary battery cell has one cell electrode and the other cell electrode exposed on one of the cell end faces, the holder insulating portion forms a plurality of storage tubes with one edge open, each of which individually houses each secondary battery cell, the holder conductive portion is formed in a plate shape provided on the open end side of the storage tube, and has a holder opening window at least partially open at a position corresponding to each open end, the other cell electrode of the one cell end face exposed on the open end side of the storage tube of the secondary battery cell stored in the storage tube is electrically connected to the holder conductive portion, and the one cell electrode is exposed from the holder opening window of the holder conductive portion and connected to the lead plate.

[0024] In addition, a power supply device according to another aspect of the present disclosure is any of the above-described aspects, further including an insulating holder cover interposed between the lead plate and the holder conductive portion, the holder cover having a cover opening window at a position facing the cell end face of the secondary battery cell, the lead plate having a lead opening window at a position facing the cell end face of the secondary battery cell, the lead plate having a current collecting tab protruding from the lead opening window, and the current collecting tab being connected to one of the cell electrodes on the cell end face of the secondary battery cell through the cover opening window and the holder opening window. With the above configuration, the lead plate and the holder conductive portion are insulated from each other by the insulating holder cover, and the lead plate can be electrically connected to one of the cell electrodes.

[0025] Furthermore, in a power supply device according to another embodiment of the present disclosure, in any of the above embodiments, the holder conductive portion is provided with a holder connection portion exposed on one of the cell end faces of the secondary battery cell for connecting to the other cell electrode.

[0026] 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.

[0027] The power supply device of the present disclosure can be used as a driving power source for mobile objects such as forklifts, construction machinery, hybrid vehicles, electric vehicles, electric carts, electric scooters, and assisted bicycles, as a power source for portable electrical equipment such as power tools and electric cleaners, or as a stationary power storage power source for servers, or as a power supply device for home, office, or factory use. Hereinafter, a power supply device used as a driving power source for an electric mobile object will be described as one embodiment of the present invention. [Embodiment 1]

[0028] 1A and 1B show a power supply device 100 according to a first embodiment of the present disclosure. The power supply device 100 shown in these figures includes a plurality of secondary battery cells 1, a plurality of lead plates 3, and a battery holder 2. (Secondary Battery Cell 1)

[0029] The battery holder 2 holds a plurality of secondary battery cells 1. Each of the plurality of secondary battery cells 1 has a pair of cell end faces 1a and a cell side face located between the cell end faces 1a. Each secondary battery cell 1 also has a pair of cell electrodes, i.e., a positive electrode and a negative electrode. One of the pair of cell electrodes is exposed on one of the pair of cell end faces 1a.

[0030] Such secondary battery cells 1 may be cylindrical or rectangular in shape. In the example shown in FIG. 1B , the outer can holds the cylindrical secondary battery cells 1 in a vertical orientation with the cell end faces 1 a aligned on the same plane using a battery holder 2. The number and arrangement of the secondary battery cells 1 are not limited to this example, and any number and arrangement may be used. For example, cylindrical secondary battery cells may be aligned so that the cell end faces form a matrix. Matrix-aligned secondary battery cells may be aligned in any desired arrangement, such as by arranging the cell end faces in a grid pattern or by offsetting the cell end faces in a staggered pattern. Known secondary batteries, such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, may be used for such secondary 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. 1B etc., 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 the negative electrode.

[0032] The multiple secondary battery cells 1 are connected in series or in parallel via lead plates 3. The number of series connections or parallel connections can be set as desired according to the required specifications. In the example shown in Figures 1A and 1B, 15 secondary battery cells 1 are connected in a 3 series x 5 parallel configuration with each lead plate 3. 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. (Lead plates 3)

[0033] A plurality of secondary battery cells 1 are held in a battery holder 2. A plurality of lead plates 3 are connected to one cell end surface 1a of each secondary battery cell 1 held in the battery holder 2, electrically connecting the secondary battery cells 1 to each other. The lead plates 3 are made of metal plates with excellent conductivity, such as aluminum, nickel, or copper. The plurality of secondary battery cells 1 are connected in series or parallel via the lead plates 3.

[0034] Each lead plate 3 is fixed to the top surface of the battery holder 2. Each lead plate 3 has a lead opening window 4 formed in a position facing the cell end surface 1a of the secondary battery cell 1, partially exposing the cell end surface 1a. Each lead plate 3 also has a current collecting tab 5 protruding from the lead opening window 4. The current collecting tab 5 is a member for connecting to the cell electrode on the cell end surface 1a of the secondary battery cell 1. Each current collecting tab 5 is bent in the middle and protrudes diagonally downward, absorbing slight misalignment and making it possible to adjust the fixing position and height relative to the cell electrode. (Battery holder 2)

[0035] The battery holder 2 holds multiple secondary battery cells 1 and multiple lead plates 3. This battery holder 2 is constructed by integrally joining an insulating holder insulating part 10 and a conductive holder conductive part 20. The holder insulating part 10 is preferably made of a material with excellent insulating properties, such as a resin such as polycarbonate or PC-ABS alloy. (Holder conductive part 20)

[0036] The holder conductive parts 20 are composed of multiple parts. Each holder conductive part 20 forms part of the electrical connection between the cell end surface 1a of each secondary battery cell 1 and each lead plate 3. The holder conductive parts 20 are preferably made of a metal member such as aluminum or its alloy. In this way, making part of the battery holder 2 conductive and having it handle part of the electrical connection of the secondary battery cells 1 simplifies the electrical connection using the lead plates 3. (Storage tube 6)

[0037] The battery holder 2 has multiple cylindrical storage sections 6 for individually storing each rechargeable battery cell 1. Each cylindrical storage section 6 has an opening on at least one edge. In the example shown in Fig. 1B, the cylindrical storage sections 6 are formed in the holder insulating section 10 of the battery holder 2. This allows the side surfaces of each rechargeable battery cell 1 to be covered with the holder insulating section 10, providing insulation and preventing unintended electrical conduction.

[0038] It is also preferable that at least a portion of the holder conductive part 20 is exposed on the bottom surface of each cylindrical storage 6. In the example of Fig. 1B, the cylindrical storage 6 is formed so that the upper and lower end surfaces of the holder insulating part 10 are open, and the holder conductive part 20 is exposed on the end surface of the cylindrical storage 6.

[0039] Furthermore, the lead plate 3 is electrically connected to one of the cell electrodes (positive electrode in the example of Figure 1B) exposed on the cell end surface 1a at the open end of the storage tube 6. With this configuration, only one cell electrode is connected by the lead plate 3, and the other cell electrode is electrically connected by the holder conductive part 20 of the battery holder 2, thereby simplifying the electrical connection.

[0040] Secondary battery cells generate heat during charging and discharging, and the amount of heat generated has tended to increase due to recent demands for higher output and capacity in power supply devices. Therefore, while there is a need to improve the heat dissipation capabilities of power supply devices, lead plates are made of thin metal plates, e.g., approximately 0.25 mm thick, which results in insufficient heat dissipation and thermal capacity. Therefore, a structure in which thick metal current collector plates are placed on top of the lead plates has been considered to improve the heat dissipation capabilities of the lead plates. However, adding current collector plates requires additional raw material costs and increases manufacturing costs, such as welding the current collector plates.

[0041] On the other hand, a one-sided current collection structure has been proposed in which the positive and negative electrodes are connected to one of the cell end faces 1a of the secondary battery cell. In this case, as shown in the battery module 500 shown in FIG. 5, the lead plate 503 inevitably becomes thin. Meanwhile, the lead plate 503 is generally manufactured by press-molding a thin metal plate such as aluminum. However, increasing the thickness of such a thin lead plate 503 results in a longer thickness relative to the thinness, making it unsuitable for press manufacturing. Considering the ease of mass production of lead plates and manufacturing costs, press molding is desirable, and a simpler lead plate that can be press-molded is desired.

[0042] In light of this background, in the power supply device 100 of this embodiment, as shown in Figures 1A and 1B, the battery holder 2 has a hybrid structure made up of an insulating holder insulating portion 10 and a conductive holder conductive portion 20, and by having the battery holder 2 handle part of the electrical connection of the secondary battery cells 1, electrical connection by the lead plate 3 is simplified and the heat dissipation properties of the holder conductive portion 20 on the battery holder 2 side are exhibited, improving the heat dissipation properties of the entire power supply device.

[0043] Each secondary battery cell 1 has one cell electrode exposed on one cell end surface 1a and the other cell electrode exposed on the other cell end surface 1a. The holder conductive part 20 is electrically connected to the other cell electrode exposed on the other cell end surface 1a of each secondary battery cell 1. In the example of Figures 1A and 1B, the positive electrode is exposed on the top cell end surface 1a and the negative electrode is exposed on the bottom cell end surface 1a, and the bottom surface is connected to the holder conductive part 20.

[0044] Each holder conductive part 20 is formed in an L-shape in cross section. The holder conductive part 20, which is formed in an L-shape in cross section, has an end exposed on the upper surface side of the battery holder 2. In the example shown in FIGS. 1A and 1B, the cell end surfaces 1a on the bottom side of five secondary battery cells 1 are placed on one L-shaped piece 21 of the holder conductive part 20. In other words, it is connected to the negative electrodes of the secondary battery cells 1. The other piece 22 of the holder conductive part 20 is bent vertically, and the upper edge of this other piece is exposed and separated from the storage tube 6 of the battery holder 2, forming a holder conductive joint area 23.

[0045] The lead plate 3 is connected to one cell electrode (positive electrode) on the cell end surface 1a of the top surface of the rechargeable battery cell 1, which is exposed at the open end of the cylindrical storage tube 6 on the top surface of the battery holder 2. The periphery of the lead plate 3 is also connected to the holder conductive joint area 23 of the holder conductive part 20. In this way, one-sided current collection is achieved on the top surface of the battery holder 2, connecting the lead plate 3 to the positive and negative electrodes of the rechargeable battery cell 1. Furthermore, because the lead plate 3 only needs to be connected to one electrode of the rechargeable battery cell 1 (the positive electrode in the example of FIG. 1A), it can be easily manufactured using conventional methods such as press molding. Furthermore, by using the holder conductive part 20 to connect the other electrode of the rechargeable battery cell 1 (the negative electrode in the example of FIG. 1B), a relatively large area, such as the edge of the lead plate 3, can be utilized, resulting in a simplified structure of the lead plate 3 and the battery holder 2.

[0046] Furthermore, as shown in FIG. 1B, by covering part of the periphery of the cell side of the secondary battery cell 1 with the holder conductive part 20 bent into an L shape, heat dissipation is also improved.

[0047] Furthermore, each holder conductive part 20 is embedded in the holder insulating part 10 so as to straddle the cell end faces 1 a of adjacent secondary battery cells 1. This allows each holder conductive part 20, which is L-shaped in cross section, to electrically connect the cell end faces 1 a of multiple secondary battery cells 1 inside the battery holder 2, simplifying the electrical connection structure.

[0048] The holder insulating portion 10 exposes the holder conductive bonding area 23 at the edge of each holder conductive portion 20. Furthermore, it insulates the edges of adjacent holder conductive portions 20 between adjacent cylindrical storage tubes 6. In this state, the lead plate 3 electrically connects the cell end surfaces 1a of adjacent rechargeable battery cells 1 exposed at the open ends of adjacent cylindrical storage tubes 6. This configuration prevents short-circuiting of the rechargeable battery cells 1 between adjacent cylindrical storage tubes 6, while allowing the lead plate 3 to be stretched across the adjacent cylindrical storage tubes 6 for electrical connection. Furthermore, the cylindrical storage tube 6 is formed as the holder insulating portion 10 to insulate the necessary areas of the rechargeable battery cells 1. Specifically, the bottom cell end surface 1a of the rechargeable battery cells 1 is insulated from the rechargeable battery cells not connected by the conductive adhesive layer 30 by covering the cell side. In other words, for rechargeable battery cells 1 to which one L-shaped piece 21 of the holder conductive portion 20 is electrically connected, there is no problem if the other piece 22 of the holder conductive portion 20 comes into contact with the cell side. (Conductive adhesive layer 30)

[0049] The interface between the cell end surface 1 a on the bottom side of each secondary battery cell 1 and the holder conductive part 20 is fixed by a conductive adhesive layer 30. The conductive adhesive layer 30 is electrically conductive and fixes the electrode (negative electrode) on the cell end surface 1 a to the holder conductive part 20 in an electrically connected state. This allows the cell end surface 1 a of the secondary battery cell 1 to be reliably fixed in an electrically connected state to the holder conductive part 20. The conductive adhesive material used to form the conductive adhesive layer 30 is made by mixing conductive particles such as Ag, Au, Al, Pt, or Ti with a resin that serves as the base material for the adhesive. Other connection methods that do not use a conductive adhesive layer include welding and metal springs.

[0050] Uncured conductive adhesive is applied to the bottom surface of the cylindrical storage tube 6 before the rechargeable battery cell 1 is inserted into the cylindrical storage tube 6. The conductive adhesive is then cured to form a conductive adhesive layer 30, securing the rechargeable battery cell 1 within the cylindrical storage tube 6. Preferably, the adhesive is applied not only to the cell end surface 1 a of the rechargeable battery cell 1 but also to a portion of the cell side surface extending from the cell end surface 1 a. For example, a larger amount of conductive adhesive is applied, and the bottom surface of the rechargeable battery cell 1 is pressed against the bottom surface of the cylindrical storage tube 6 to spread the uncured conductive adhesive, allowing some of it to penetrate between the cell side surface and the side surface of the cylindrical storage tube 6. This secures the cell side surface as well, further securing the rechargeable battery cell 1. In particular, when using a cylindrical rechargeable battery cell 1, the rechargeable battery cell 1 may rotate due to impact, vibration, or the like while inserted into the cylindrical storage tube 6. In this case, there is a concern that the connection between the rechargeable battery cell 1 and the lead plate 3 may be damaged by the rotation. To prevent this from happening, the cell side of the secondary battery cell 1 is also at least partially fixed inside the storage cylinder 6, thereby suppressing rotation and improving the reliability of the electrical connection of the secondary battery cell 1.

[0051] In the above example, as an example of a one-sided current collection structure, an example was shown in which the lead plate 3 is connected to the cell end surface 1a on the top side of the secondary battery cell 1, but it goes without saying that this configuration is not limited to this, and the lead plate may be connected to the cell end surface on the bottom side, for example. [Embodiment 2]

[0052] In the power supply device 100 according to the first embodiment described above, the cell side surfaces of each secondary battery cell 1 are insulated by the holder insulating portion 10. However, the present disclosure is not limited to this configuration, and the cell side surfaces may be covered by the holder conductive portion. Such an example is shown in FIGS. 2A and 2B as a power supply device 200 according to a second embodiment. In these figures, components similar to those in the power supply device 100 according to the first embodiment described above are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0053] In the power supply device 200 according to the second embodiment, each holder conductive part 20B forms a cylindrical storage tube 6B with one end open and a bottom. Here, a plurality of cylindrical storage tubes 6B, each housing adjacent ones of a plurality of secondary battery cells 1, are connected together to form an integrated structure. In the example shown in FIGS. 2A and 2B, five cylindrical storage tubes 6B, each housing five secondary battery cells 1, are connected in two tiers, with three tiers offset from the other two, to form a holder conductive part 20B. Such holder conductive parts 20B are formed by casting or the like.

[0054] The holder conductive portion 20B is also surrounded by a holder insulating portion 10B, with the open end of each cylindrical storage tube 6B exposed through the holder insulating portion 10B. This battery holder 2B has a relatively simple configuration, offering the advantage of easy manufacturing. In particular, the power supply unit 100 of the first embodiment shown in FIG. 1B requires complex manufacturing processes to manufacture the battery holder 2. The cylindrical storage tube 6 is formed in the holder insulating portion 10, and the L-shaped cross-sectional holder conductive portion 20 is embedded in the holder insulating portion 10 so that the holder conductive portion 20 contacts the bottom cell end surface 1a while insulating the rechargeable battery cells 1 to a necessary extent. In contrast, the battery holder 2B shown in FIG. 2B has a relatively simple configuration in which the holder insulating portion 10B covers the periphery of the holder conductive portion 20B, which connects multiple cylindrical storage tubes 6B, with the open end exposed, making it easier to manufacture. Additionally, by covering the periphery of the cell side of the secondary battery cell 1 with the holder conductive part 20B, which has excellent thermal conductivity, there is also the advantage of improved heat dissipation. (Holder cover 40)

[0055] Furthermore, unlike the power supply device 200 in FIG. 1B , the power supply device 200 in FIG. 2B does not have an insulating member such as a holder insulating part 10B between the cell end faces 1a of adjacent secondary battery cells 1. Therefore, when performing one-sided current collection from these cell end faces 1a, insulation between the adjacent cell end faces 1a is necessary. For this reason, the power supply device 200 in FIG. 2B includes an insulating holder cover 40 interposed between the lead plate 3 and the open end of the cylindrical storage tube 6B of the holder conductive part 20B. The holder cover 40 at least partially covers the upper surface of the battery holder 2B, including the area between the cell end faces 1a of the secondary battery cells 1 exposed from the adjacent cylindrical storage tubes 6B. This prevents unintentional short-circuiting between the open end of the cylindrical storage tube 6B of the holder conductive part 20B and the lead plate 3. The holder cover 40 is made of a resin with excellent insulating properties, such as polycarbonate or PC-ABS alloy.

[0056] The lead plate 3 also has a step corresponding to the thickness of the holder cover 40. This allows the lead plate 3 to be placed on top of the insulating holder cover 40. The step is formed by bending the current collecting tab 5 extending from the lead plate 3 to the cell electrode on the cell end surface 1a not covered by the holder cover 40, for example, when the lead plate 3 is placed on top of the holder cover 40, and extending beyond the thickness of the holder cover 40 to connect the lead plate 3 to the cell electrode via the current collecting tab 5. In this example, the current collecting tab 5 extending from the lead plate 3 constitutes the step. [Embodiment 3]

[0057] In the power supply device 200 according to the second embodiment, the bottom surface of the holder conductive portion 20B, which forms the cylindrical storage tube 6B, is covered with a holder resin portion. However, the present disclosure is not limited to this configuration, and the bottom surface of the holder conductive portion may be exposed from the battery holder. Such an example is shown in Figures 3A and 3B as a power supply device 300 according to a third embodiment. In these figures, the same components as those in the first embodiment and other embodiments are designated by the same reference numerals and detailed descriptions are omitted.

[0058] In the power supply device 300 shown in Figures 3A and 3B, the rear side of the bottom surface of the cylindrical storage tube 6C formed in the holder conductive portion 20C that abuts against the cell end surface 1a is exposed from the holder insulating portion 10C. This configuration exposes the bottom side of the rechargeable battery cell 1 from the battery holder 2C, improving the cooling efficiency on the bottom side. In other words, the cell end surface 1a on the bottom side of the rechargeable battery cell 1 can be used as a heat dissipation area. For example, by arranging a cooling mechanism such as a cooling plate on the bottom side of the battery holder 2C and thermally coupling it to each rechargeable battery cell 1, the rechargeable battery cell 1 can be individually cooled, improving cooling capacity.

[0059] Furthermore, the bottom cell end surface 1a of the secondary battery cell 1 can be fixed to the bottom surface of the cylindrical storage tube 6C formed on the holder conductive part 20C using a conductive adhesive or by welding. This has the advantage of allowing the exposed bottom surface of the battery holder 2C to be easily welded to the holder conductive part 20C. For example, laser welding can be performed on the exposed bottom surface of the battery holder 2C to form a weld layer 30C between the bottom cell end surface 1a of the secondary battery cell 1 and the holder conductive part 20C, thereby establishing an electrical connection. This eliminates the need for applying and curing a conductive adhesive. Furthermore, welding directly joins the cell electrodes of the secondary battery cell 1 to the holder conductive part 20C without an intervening layer such as a conductive adhesive layer, thereby reducing contact resistance at the interface and improving conductivity.

[0060] In the above example, electrical connection is made using the cell end surface 1a of each secondary battery cell 1, but the present disclosure is not limited to this configuration and the cell side surface may also be used. In particular, if one cell electrode is exposed on one cell end surface and the other cell electrode is exposed on the cell side surface, the cell electrode on this side surface can be used to electrically connect to the other cell electrode exposed on the cell side surface of each secondary battery cell via the holder conductive part. With this configuration, electrical connection is made using the cell electrode exposed on the cell side surface via the holder conductive part of the battery holder, simplifying electrical connection using lead plates. [Embodiment 4]

[0061] In the above-described first to third embodiments, an example has been described in which one cell electrode and the other cell electrode are drawn out from one cell end face 1a and the other cell end face 1a of the secondary battery cell 1, respectively, for electrical connection. However, the present disclosure is not limited to this configuration, and one cell electrode and the other cell electrode may be drawn out from only one cell end face of the secondary battery cell for electrical connection. Such an example is shown in FIGS. 4A and 4B as a power supply device 400 according to a fourth embodiment. In these figures, components similar to those in the power supply device according to the first embodiment and the like are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0062] 4A and 4B, one cell electrode and the other cell electrode are exposed on one cell end surface 1a of the secondary battery cell 1. Here, on the cell end surface 1a on the upper surface of the secondary battery cell 1, a positive electrode terminal 1b is exposed in the center of the circle, and a negative electrode is exposed on the circumferential side.

[0063] The holder insulating portion 10D that constitutes the battery holder 2D also forms multiple cylindrical storage sections 6D that individually store each rechargeable battery cell 1. Each cylindrical storage section 6D has an opening on one edge (here, the top surface).

[0064] On the other hand, the holder conductive part 20D is formed in a plate shape and provided on the open end side of the cylindrical storage 6D. The plate-shaped holder conductive part 20D also has holder opening windows 24 at positions corresponding to the open ends of the cylindrical storage 6D.

[0065] Furthermore, an insulating holder cover 40D is interposed between the lead plate 3 and the holder conductive portion 20D. The holder cover 40D has a cover opening window 44 at a position facing the cell end surface 1a of the secondary battery cell 1.

[0066] In this power supply device 400, the other cell electrode of one cell end surface 1a of a secondary battery cell 1 stored in a cylindrical storage tube 6D, exposed at the open end of the cylindrical storage tube 6D, is electrically connected to the holder conductive part 20D, and one cell electrode is exposed through a holder opening window 24 of the holder conductive part 20D and connected to a lead plate 3. Specifically, the lead plate 3 has a lead opening window 4 at a position facing the cell end surface 1a of the secondary battery cell 1. Furthermore, the lead plate 3 has a current collecting tab 5 protruding from the lead opening window 44. This current collecting tab 5 is connected to one cell electrode (positive terminal 1b) of the cell end surface 1a of the secondary battery cell 1 through the cover opening window 44 and the holder opening window 24. This allows the lead plate 3 to be electrically connected to one cell electrode while the lead plate 3 and the holder conductive part 20D are insulated by the insulating holder cover 40D. On the other hand, the holder conductive part 20D has a holder connection part 25 that is exposed on one cell end face 1a of the secondary battery cell 1 and that is for connecting to the other cell electrode (negative electrode). In the example of Figures 4A and 4B, the positive electrode is connected to the current collecting tab 5 of the lead plate 3 at the center of the top-side cell end face 1a that is opened through the lead opening window 4 and the cover opening window 44. The negative electrode is connected to the holder connection part 25 of the holder conductive part 20D around the circumference of the cell end face 1a. This makes it possible to achieve one-sided current collection with a relatively simple three-layer structure in which the lead plate 3 and the holder conductive part 20D are insulated by the holder cover 40D at the top-side cell end face 1a.

[0067] 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.

[0068] The power supply device according to the present disclosure can be suitably used as a driving power source for mobile objects such as forklifts, construction machinery, hybrid vehicles, electric vehicles, electric carts for golf courses, self-propelled delivery robots and electric delivery scooters, and power-assisted bicycles. It can also be used as a power source for portable electrical devices 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.

[0069] DESCRIPTION OF SYMBOLS 100, 200, 300, 400... Power supply device 1... Secondary battery cell 1a... Cell end surface; 1b... Positive terminal 2, 2B, 2C, 2D... Battery holder 3... Lead plate 4... Lead opening window 5... Current collecting tab 6, 6B, 6C, 6D... Storage cylinder 10, 10B, 10C, 10D... Holder insulating part 20, 20B, 20C, 20D... Holder conductive part 21... L-shaped one piece 22... Other piece 23... Holder conductive bonding area 24... Holder opening window 25... Holder connection part 30... Conductive adhesive layer; 30C... Welded layer 40, 40D... Holder cover 44... Cover opening window 500... Battery module 501... Secondary battery cell 503... Lead plate

Claims

1. A power supply device comprising: a plurality of secondary battery cells, each having a pair of cell end faces and cell side faces connecting the cell end faces, with one of the pair of cell electrodes exposed on one of the cell end faces; a plurality of lead plates connected to the one cell end face of each secondary battery cell and electrically connecting the secondary battery cells; and a battery holder that holds the plurality of secondary battery cells and the plurality of lead plates, wherein the battery holder is composed of an insulating holder insulating part and a conductive holder conductive part that are integrally joined together, and the holder conductive part forms part of the electrical connection between the cell end face of each secondary battery cell and each lead plate.

2. A power supply device according to claim 1, wherein each secondary battery cell has the other cell electrode exposed on the other cell end face, and the holder conductive part is electrically connected to the other cell electrode exposed on the other cell end face of each secondary battery cell.

3. A power supply device according to claim 1, wherein each secondary battery cell has the other cell electrode exposed on the cell side surface, and the holder conductive part is electrically connected to the other cell electrode exposed on the cell side surface of each secondary battery cell.

4. A power supply device as claimed in claim 1, wherein the battery holder forms a plurality of cylindrical storage sections with one edge open, each of which stores a secondary battery cell individually; a plurality of conductive holder sections are provided so that at least a portion of each is exposed on the bottom surface of each cylindrical storage section; and the lead plate is electrically connected to one of the cell electrodes exposed on the cell end surface at the open end of the cylindrical storage section.

5. A power supply device according to claim 4, wherein each holder conductive part is formed in an L-shape in cross section.

6. A power supply device according to claim 5, wherein the cell side surfaces of each secondary battery cell are covered with the holder insulating portion.

7. A power supply device according to claim 5, wherein each holder conductive part is embedded in the holder insulating part so as to straddle the cell end faces of adjacent secondary battery cells.

8. A power supply device as claimed in claim 5, wherein the holder insulating part exposes the edge of each holder conductive part and insulates the edge of the adjacent holder conductive parts between the adjacent storage cylinders.

9. A power supply device according to claim 4, further comprising a conductive adhesive layer that fixes the cell end face of each secondary battery cell and the interface with the holder conductive part in an electrically connected state.

10. A power supply device as claimed in claim 4, wherein each holder conductive part forms the storage cylinder that stores adjacent secondary battery cells out of the plurality of secondary battery cells, and the adjacent storage cylinders are connected to each other to form an integrated structure, and the holder conductive part is embedded in the holder insulating part, and the open end of each storage cylinder is exposed from the holder insulating part.

11. A power supply device according to claim 10, further comprising an insulating holder cover interposed between said lead plate and the open end of said cylindrical housing of said holder conductive portion.

12. A power supply device according to claim 11, wherein the lead plate has a step corresponding to the thickness of the holder cover.

13. A power supply device as claimed in claim 4, wherein the holder conductive part embedded in the holder insulating part has the back side of the bottom surface that abuts against the cell end face exposed from the holder insulating part.

14. The power supply device according to claim 13, wherein the secondary battery cell is welded to the bottom surface of the holder conductive part.

15. A power supply device as claimed in claim 1, wherein the secondary battery cells have one cell electrode and the other cell electrode exposed on one of the cell end faces, the holder insulating section forms a plurality of storage tubes with one edge open, each storing a respective secondary battery cell individually, the holder conductive section is formed in a plate shape provided on the open end side of the storage tube, and has holder opening windows at least partially open at positions corresponding to each open end, the other cell electrode of the one cell end face exposed on the open end side of the storage tube of the secondary battery cell stored in the storage tube is electrically connected to the holder conductive section, and the one cell electrode is exposed from the holder opening window of the holder conductive section and connected to the lead plate.

16. A power supply device as defined in claim 15, further comprising an insulating holder cover interposed between the lead plate and the holder conductive portion, wherein the holder cover has a cover opening window at a position facing the cell end face of the secondary battery cell, and the lead plate has a lead opening window at a position facing the cell end face of the secondary battery cell, and the lead plate has a current collecting tab protruding from the lead opening window, and the current collecting tab is connected to one of the cell electrodes on the cell end face of the secondary battery cell through the cover opening window and the holder opening window.

17. A power supply device according to claim 16, wherein the holder conductive portion comprises a holder connecting portion exposed on one cell end face of the secondary battery cell for connecting to the other cell electrode.

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