Battery pack

Abstract

By narrowing the internal ducts, a high level of safety is achieved while preventing thermal runaway in other battery cells. [Solution] The battery pack comprises a battery unit 3 of multiple battery cells 4 and a case 5 for housing them. Each battery cell 4 has an discharge end face 6A and a non-discharge end face 6B. The battery unit 3 arranges the battery cells 4 in a parallel position with the cell end faces 6 on the same plane and places lead plates 8 on the unit electrode surface 7. The case 5 has an internal duct 9 inside. The lead plates 8 are arranged on both sides of the internal duct 9, forming a discharge permeable region 8A that covers the discharge end face 6A and opens a permeable opening 11, and a dispersion and occlusion region 8B that covers the non-dischargeable end face 6B and discharges ejected from the permeable opening 11. Furthermore, at least the surface of the dispersion and occlusion region 8B of the lead plates 8 has a heat insulating plate 12 laminated on it, so that the discharges ejected from the permeable opening 11 into the internal duct 9 are reflected by the surface and dispersed within the internal duct 9.

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack in which a battery unit composed of a plurality of battery cells is housed in a case, and particularly relates to a battery pack that prevents thermal damage caused by high-temperature and high-pressure exhaust discharged from the battery cells. [Background Art]

[0002] For a battery pack including a plurality of battery cells, a structure is used in which a plurality of battery cells are connected in series or parallel via lead plates to form battery units, and the plurality of battery units are housed in a case. In order to ensure safety, this battery pack needs to smoothly guide and discharge the high-temperature and high-pressure exhaust emitted by the battery cells constituting each battery unit to the outside of the case. As a structure for discharging exhaust out of the case, battery packs provided with internal ducts between the respective battery units for receiving the ejected exhaust have been developed. A battery pack with this structure is required to have a structure that solves the problem that when one of the battery cells undergoes thermal runaway and ejects high-temperature, high-pressure exhaust into the duct, the exhaust overheats other battery cells and induces thermal runaway. As a structure for solving this problem, a structure has been developed in which the inner spacing of internal ducts provided between battery units housed in a case is set to the minimum safe gap (Patent Document 1). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese National Publication No. 2024-522151 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] The battery pack disclosed in Patent Document 1 has a wide internal duct between battery units, which is designated as a "safety gap." However, this structure has the problem of increasing the external dimensions of the battery pack because the internal duct serves as the safety gap. The external dimensions can be reduced by narrowing the internal duct, but if the internal duct is narrowed, the high-temperature, high-pressure exhaust ejected into the internal duct can overheat other battery cells, inducing thermal runaway. The safety gap of the internal duct cannot be narrowed in order to prevent the exhaust from inducing thermal runaway in other battery cells. When high-temperature, high-pressure exhaust is ejected into an internal duct with a narrow inner spacing, it is not possible to reliably prevent thermal runaway in the battery cell that is directly hit by the exhaust. Thermal runaway in other battery cells due to exhaust can be prevented by placing a heat-resistant plate along the center of the internal duct. However, this structure requires two rows of internal ducts divided on both sides of the heat-resistant plate, which makes the structure complex and further increases component and assembly costs. Furthermore, since it has two rows of internal ducts, there is a problem that the effective width cannot be narrowed by the two rows of internal ducts. In addition, the flow velocity of the discharged material flowing through the narrow internal ducts is also high, which presents a problem as the discharged material is expelled from the case at high speed.

[0005] The present invention was further developed with the aim of solving the above problems, and one of the objectives of this disclosure is to provide a battery pack that can achieve high safety by narrowing the internal duct while preventing the induction of thermal runaway in other battery cells caused by exhaust fumes ejected from the battery cell into the internal duct. [Means for solving the problem]

[0006] A battery pack according to one embodiment of the present disclosure comprises a battery unit consisting of a plurality of battery cells and a case housing the plurality of battery units. Each battery cell has one end face as an exhaust end face and the other end face as a non-exhaust end face from which exhaust is ejected. The battery unit has a plurality of battery cells arranged in a parallel position with their end faces on the same plane, and the plane on which the cell end faces are arranged is the unit electrode surface. Lead plates, which are made by connecting the battery cells in series or parallel, are arranged on this unit electrode surface. The case is provided with an internal duct for safely discharging the exhaust ejected from the battery cells to the outside of the case. The internal duct is positioned opposite the battery units and guides the exhaust ejected from the battery units to the outside of the case. The internal duct is structured so that the exhaust end face and non-exhaust end face of the battery cells are positioned opposite each other on both sides and the exhaust ejected from the exhaust end face is ejected toward the non-exhaust end face. The lead plates are positioned on both sides of the internal duct. Permeable openings are provided in the region covering the discharge end face of the battery cell, creating a permeable region that allows the discharged material from the battery cell to pass through to the internal duct. The region covering the non-discharge end face of the battery cell does not have permeable openings for the discharged material, instead creating a dispersion-blocking region that reflects and disperses the discharged material ejected from the permeable opening into the internal duct. Furthermore, the lead plates have thermal insulation plates laminated on at least the surface of the dispersion-blocking region. The thermal insulation plates laminated in the dispersion-blocking region reflect the discharged material ejected from the permeable opening into the internal duct, dispersing it within the internal duct and preventing thermal runaway of the battery cell, whose non-discharge end face is positioned on the side of the internal duct. [Effects of the Invention]

[0007] The above battery packs have the advantage of preventing thermal runaway of other battery cells caused by exhaust fumes ejected from the battery cells into internal ducts within the case, while also ensuring high safety by narrowing the internal ducts that expel the battery cell exhaust fumes to the outside of the case. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall perspective view showing the battery pack according to Embodiment 1. [Figure 2] Figure 1 is an exploded view of the battery pack. [Figure 3] Figure 1 is a vertical cross-sectional view of the battery pack. [Figure 4] This is an enlarged cross-sectional view of the main part of Figure 3, showing the internal duct. [Figure 5] This is an exploded view showing the circuit board assembly separated from the core pack. [Figure 6] This is an exploded view from another direction showing the circuit board assembly separated from the core pack. [Figure 7] This is a schematic overview of the core pack. [Figure 8] This is a disassembled perspective view of the core pack. [Figure 9] This is a disassembled perspective view of the battery unit from a diagonal upward angle. [Figure 10] This is a disassembled perspective view of the battery unit from a diagonal downward angle. [Figure 11] This is an enlarged cross-sectional view of the main part of a battery pack according to another embodiment. [Figure 12] This is an enlarged cross-sectional view of the main part of the upper surface duct. [Figure 13] This is an enlarged cross-sectional view of the main part of the surface duct below. [Figure 14] This is a schematic connection diagram. [Figure 15] This is another schematic connection diagram. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating the understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments described below illustrate specific examples of the technical concept of the present invention and do not limit the present invention to those described below. Also, the dimensions, materials, shapes, relative arrangements, etc., of the components described below are intended to be illustrative, and not to limit the scope of the present invention unless otherwise specified. Moreover, the content described in one embodiment or example is applicable to other embodiments and examples. Additionally, the size and positional relationships of the members shown in the drawings may be exaggerated for clarity.

[0010] A battery pack according to one embodiment of the present disclosure comprises a battery unit consisting of a plurality of battery cells and a case housing the plurality of battery units. Each battery cell has one end face as an exhaust end face and the other end face as a non-exhaust end face from which exhaust is ejected. The battery unit has a plurality of battery cells arranged in a parallel position with their end faces on the same plane to form a unit electrode surface. Lead plates are arranged on the unit electrode surface, connected in series or parallel to the battery cells. The case has an internal duct for discharging the exhaust ejected by the battery cells to the outside of the case, and the battery units are positioned opposite the internal duct. The internal duct has an exhaust end face and a non-exhaust end face positioned opposite each other on both sides, so that the exhaust ejected from the exhaust end face into the internal duct is blown onto the surface of the non-exhaust end face. The lead plates are arranged on both sides of the internal duct, and permeable openings are made in the region covering the exhaust end face of the battery cell, making this region a permeable region for the exhaust. Furthermore, the lead plate does not have a permeable opening in the region covering the non-discharge end face of the battery cell, and instead forms a dispersion-blocked region that reflects and disperses the discharged material ejected from the permeable opening. In addition, the lead plate has a heat-insulating plate laminated on at least the surface of the dispersion-blocked region, and the heat-insulating plate laminated on the dispersion-blocked region reflects the discharged material ejected from the permeable opening into the internal duct at its surface and disperses it within the internal duct.

[0011] The above battery pack has the feature of being able to prevent the induction of thermal runaway in other battery cells caused by exhaust emitted from a thermally runaway battery cell while narrowing the inner spacing (d) of the internal duct. This is because, in the pair of battery units arranged on both sides of the internal duct, the discharge end face and non-discharge end face of each battery cell are arranged at opposing positions on both sides of the internal duct; the region covering the discharge end face of the battery cell is used as an exhaust permeation region where an exhaust permeation opening is opened, and the region covering the non-discharge end face is used as a dispersion blocking region where no permeation opening is opened and which disperses exhaust sprayed onto the surface, and a heat insulating and insulating plate is laminated on the surface of the dispersion blocking region of the lead plate. In the above battery pack, exhaust emitted from a thermally runaway battery cell passes through the permeation opening of the lead plate and is ejected into the internal duct, and the ejected exhaust is sprayed onto the heat insulating and insulating plate on the surface of the dispersion blocking region located at the position opposing the permeation opening. The heat insulating and insulating plate laminated on the dispersion blocking region of the lead plate reflects the high-temperature and high-pressure exhaust ejected from the discharge end face at the opposing position into the internal duct on its surface, thereby preventing thermal runaway of the battery cell. For the battery cell located at the position opposing the permeation opening, since the exhaust ejected into the internal duct is sprayed toward the cell end face of the battery cell, this battery cell is the one most likely to suffer induced thermal runaway. However, the above battery pack can effectively prevent thermal runaway of the battery cell that is most susceptible to induction by means of the heat insulating and insulating plate, so that while narrowing the inner spacing (d) of the internal duct, it can reliably prevent induction of thermal runaway of battery cells caused by exhaust, and has the feature of achieving high safety.

[0012] In a battery pack according to another embodiment of the present disclosure, in addition to the above embodiment, the permeation region of the lead plate can be connected to the cell end face of the discharge end face of the battery cell. This battery pack allows a connection tab to be provided on the lead plate to open the permeation opening, and thus has the feature that the permeation region can be reliably connected to the cell electrode of the battery cell.

[0013] In a battery pack according to another embodiment of the present disclosure, in addition to the above embodiment, an air layer can be provided between the dispersion blocking region of the lead plate and the cell end face of the battery cell without connecting the dispersion blocking region to the cell end face.

[0014] The above battery pack has the advantage of being able to more effectively prevent the induction of thermal runaway in adjacent battery cells. This is because the dispersed blockage area of the lead plate, whose temperature rises when sprayed with high-temperature and high-pressure emissions, and the end surface of the cell can be thermally insulated by an air layer. The dispersed blockage area of the lead plate is located at a position facing the discharge end surface. The high-temperature and high-pressure emissions ejected from the discharge end surface are sprayed onto the heat insulating and insulating plate, causing the temperature to rise. However, since an air layer is provided between the lead plate and the cell end surface, heat conduction from the lead plate heated via the heat insulating and insulating plate to the battery cell can be blocked. Therefore, it has the advantage of being able to more effectively prevent the lead plate in the dispersed blockage area, whose temperature rises due to the emissions, from heating the approaching cell end surface and inducing thermal runaway. Furthermore, since the air layer can be provided by laminating the lead plate on the end surface plate provided in the cell holder for positioning the battery cells, it does not require a complicated structure to provide the air layer, nor does it require special components such as additional spacers. Therefore, the above battery pack also achieves the advantage of being able to effectively prevent the induction of thermal runaway while reducing manufacturing costs and component costs.

[0015] In addition to the above aspects, a battery pack according to another embodiment of the present disclosure can use a battery cell in which a cell positive electrode is provided on the discharge end surface. This battery pack has the advantage of being able to reduce battery cost as it uses cylindrical batteries, which are mass-produced for battery cells.

[0016] In addition to the above aspects, a battery pack according to another embodiment of the present disclosure can configure the transmission opening of the lead plate as a through hole of the lead plate. The lead plate with this structure has the advantage that transmission openings can be provided simply, easily, efficiently and without positional deviation by pressing a metal plate.

[0017] In addition to the above aspects, a battery pack according to another embodiment of the present disclosure can be configured such that the inner spacing (d) of the internal duct is 4 mm or more to prevent the induction of thermal runaway in battery cells.

[0018] In addition to the above embodiments, battery packs according to other embodiments of this disclosure may use an inorganic plate material for the heat insulating board. This battery pack has the advantage of being able to more effectively prevent thermal runaway by increasing the heat resistance properties of the heat insulating board.

[0019] Furthermore, a battery pack according to one embodiment of the present disclosure may use mica as the heat insulating board. This battery pack has the advantage of being able to effectively prevent the induction of thermal runaway in the battery cells by using a thin, heat-resistant mica heat insulating board.

[0020] In addition to the above embodiments, battery packs according to other embodiments of the present disclosure can be arranged such that the battery unit has multiple battery cells with their discharge end faces adjacent to each other in the longitudinal direction of the internal duct. This battery pack has the advantage of being able to more effectively prevent the induction of thermal runaway by widening the dispersed occlusion area of ​​the lead plates.

[0021] In addition to the above embodiments, battery packs according to other embodiments of the present disclosure include an internal duct located between battery units inside the case and a surface duct provided between the inner surface of the case and the surface of the core pack, so that the internal spacing (d) of the internal duct is less than twice that of the surface duct. Since the internal duct is narrowed to less than twice that of the surface duct, the induction of thermal runaway can be prevented, and thus the external dimensions of the case can be reduced while preventing the induction of thermal runaway.

[0022] In addition to the above embodiments, battery packs according to other embodiments of the present disclosure may have cylindrical battery cells, with a sealing plate for the cylindrical battery positioned on the discharge end face, and the non-discharge end face being the bottom surface of the cylindrical battery's outer casing. (Embodiment 1)

[0023] The battery pack 1 shown in Figures 1 to 10 houses multiple battery units 3, each consisting of multiple battery cells 4, in a case 5. In the battery pack 1 shown in the figures, the battery units 3 are connected to form a battery core pack 2, which is then housed in the case 5. The battery cell 4 is a secondary battery in which one cell end face 6 is designated as the discharge end face 6A for ejected waste, and the other cell end face 6 is a non-discharge end face 6B that does not eject waste. The battery unit 3 arranges multiple battery cells 4 in a parallel position with their cell end faces 6 on the same plane. The battery unit 3 arranges the cell end faces 6 on the same plane, designating this surface as the unit electrode surface 7, and places lead plates 8 on the unit electrode surface 7. The lead plates 8 are connected to the cell end faces 6 of the battery cells 4, connecting the battery cells 4 in series or parallel. The case 5 has an internal duct 9 to discharge waste ejected by the battery cells 4 to the outside of the case 5. The internal duct 9 is located between a pair of battery units 3A and 3B positioned on either side, and is a duct that discharges the waste ejected by the battery cells 4 of the battery unit 3 to the outside of the case 5. The internal duct 9 has an discharge end face 6A and a non-discharge end face 6B positioned opposite each other on both sides, so that the waste ejected from the discharge end face 6A of the battery cells 4 into the internal duct 9 is blown toward the non-discharge end face 6B of the battery cells 4 located opposite each other. The lead plates 8 are located on both sides of the internal duct 9, and the internal duct 9 is located between the lead plates 8 on both sides.

[0024] Furthermore, the lead plate 8 is provided with a permeable opening 11 in the region covering the discharge end face 6A of the battery cell 4, allowing the discharged material ejected from the battery cell 4 to flow into the internal duct 9, thus designating this region as a discharge permeable region 8A. The lead plate 8 also does not have a permeable opening 11 in the region covering the non-discharge end face 6B of the battery cell 4, and instead serves as a discharge dispersion and blockage region 8B where the discharged material ejected from the permeable opening 11 into the internal duct 9 is reflected and dispersed by its surface.

[0025] The lead plate 8 shown in the enlarged cross-sectional view of Figure 4 has a heat-insulating insulating board 12 laminated on its surface to improve its heat resistance. In the figure, the lead plate 8 has the heat-insulating insulating board 12 laminated over its entire surface, but the lead plate 8 does not necessarily have the heat-insulating insulating board 12 laminated over its entire surface; it can also be constructed in which the heat-insulating insulating board 12 is laminated on at least the surface of the dispersed blockage region 8B. The heat-insulating insulating board 12 laminated on the dispersed blockage region 8B reflects the waste discharged from the permeable opening 11 into the internal duct 9 on its surface and disperses it within the internal duct 9, thereby preventing thermal runaway of the battery cell 4 which has its cell end face 6 in the dispersed blockage region 8B. (Case 5)

[0026] The case 5 shown in Figures 1 and 2 consists of an upper case 5A and a lower case 5B connected together, with the core pack 2 housed inside. The upper case 5A has a discharge section for discharging waste to the outside. The upper case 5A is box-shaped with an open bottom, and the lower case 5B is box-shaped with an open top, and they are connected by screwing a flange into the opening. (Battery unit 3)

[0027] The cross-sectional view in Figure 3 and the enlarged cross-sectional view in Figure 4 show that battery units 3A and 3B are positioned above and below the internal duct 9, with the internal duct 9 located between the unit electrode surfaces 7 of the upper and lower battery units 3A and 3B. The battery unit 3 shown in Figures 3 to 10 has multiple battery cells 4 positioned in place by a cell holder 13. The battery cell 4 has cell end faces 6 at both ends, with one cell end face 6 being an discharge end face 6A from which discharged material is ejected, and the other cell end face 6 being a non-discharge end face 6B from which discharged material is ejected. In the enlarged cross-sectional view of Figure 4, the discharge end face 6A is used as the cell positive electrode provided on the sealing plate of the battery cell 4, and the non-discharge end face 6B is used as the cell negative electrode on the bottom surface of the outer casing of the battery cell 4. This disclosure does not specify the shape, size, arrangement, structure, etc., of the cell electrodes consisting of the cell positive electrode and cell negative electrode provided on the cell end face 6. The cell electrodes can be provided on the cell end face 6 as convex or concave portions, or as substantially flat portions. The battery cell 4 is equipped with a discharge valve (not shown) on its discharge end face 6A. The discharge valve opens in the event of a malfunction in the battery cell 4 to prevent the battery case, such as the outer casing, from rupturing. Since the discharge valve opens in the event of a malfunction, the gases, electrolytes, etc., contained in the discharged material will be at high temperature and pressure, which can cause temperature damage and fire spread, so it is necessary to properly discharge them outside the case 5.

[0028] A cylindrical battery can be used for battery cell 4, and a lithium-ion battery is suitable for battery cell 4. Lithium-ion batteries have a large charge / discharge capacity relative to their capacity and weight, allowing for a smaller and lighter battery pack 1 while maintaining a large charge / discharge capacity. However, the battery pack of this disclosure does not specify the shape, size, type, structure, electrode shape, number, or connection of the battery cells, and can use shapes other than cylindrical batteries, such as prismatic batteries, and can also use all rechargeable secondary batteries that have already been developed or will be developed in the future, such as non-aqueous electrolyte secondary batteries and all-solid-state batteries, in addition to lithium-ion batteries.

[0029] A battery cell 4 consisting of a cylindrical lithium-ion battery has the discharge end face 6A as the positive electrode and the non-discharge end face 6B as the negative electrode. In the following embodiments, the discharge end face 6A of the battery cell 4 is the positive electrode and the non-discharge end face 6B is the negative electrode. However, this disclosure is not limited to the discharge end face 6A being the positive electrode and the non-discharge end face 6B being the negative electrode of the battery cell 4, and a battery cell 4 in which the discharge end face 6A is the negative electrode and the non-discharge end face 6B is the positive electrode can also be used.

[0030] The battery pack 1 shown in the exploded perspective view of Figure 2 consists of a battery core pack 2 formed by connecting a pair of battery units 3A and 3B with insulating spacers 14. The battery pack 1 in Figure 2 has the core pack 2 housed in a case 5. This structure allows for efficient assembly of multiple battery units 3 in fixed positions within the case 5. As shown in the enlarged cross-sectional view of Figure 4, the core pack 2 has a pair of battery units 3A and 3B positioned on both sides (top and bottom in the figure) of the internal duct 9. The upper and lower battery units 3A and 3B each have their unit electrode surfaces 7 positioned above and below the internal duct 9, with the internal duct 9 located between the unit electrode surfaces 7.

[0031] The battery core pack 2, as shown in the exploded perspective views of Figures 2, 5, and 6, has a circuit board assembly 16 on which the circuit board 15 is mounted, positioned on the top surface in the figures. The circuit board assembly 16 has the circuit board 15 positioned in a fixed position on a plastic fixing frame. The enlarged cross-sectional view in Figure 12 shows a heat-resistant plate 17 placed between the circuit board assembly 16 and the core pack 2, with the heat-resistant plate 17 insulating the circuit board 15 from the core pack 2. This structure prevents problems caused by the temperature rise of the circuit board 15 due to the heat-resistant plate 17. The circuit board 15 of the circuit board assembly 16 has protection circuits and other components mounted on it that control the charge and discharge currents of the respective battery units 3A and 3B. The circuit board assembly 16 is connected to the battery unit 3 via lead wires 18.

[0032] Figure 8 shows an exploded perspective view of the core pack 2 shown in Figure 2. The core pack 2 shown in this figure has two sets of battery units 3A and 3B positioned in fixed positions above and below each other via insulating spacers 14. The insulating spacers 14 are made of plastic and are used to position the two sets of battery units 3A and 3B in fixed positions using a fitting structure (not shown), with an internal duct 9 provided between the unit electrode surfaces 7. The internal duct 9 is a duct that guides the discharged material ejected from the battery cells 4 of the battery unit 3 to the outside of the case 5.

[0033] Figures 9 and 10 are exploded perspective views of the lower battery unit 3B in the exploded perspective view of Figure 8. In the battery unit 3B shown in this figure, multiple battery cells 4 are arranged in a parallel position, and the cell end faces 6 of the battery cells 4 are placed on the same plane to form the unit electrode surface 7. The upper battery unit 3A is similar. Each of the battery units 3A and 3B holds multiple battery cells 4 in a parallel position in fixed positions using a plastic cell holder 13. In the battery unit 3 shown in Figures 8 to 10, cell holder 13A and cell holder 13B are connected to hold the battery cells 4 in fixed positions. Cell holders 13A and 13B are provided with insertion parts into which the battery cells 4 are inserted and positioned in fixed positions. Cell holders 13A and 13B are integrally molded with an end face plate 13T that supports the cell end faces 6 of the battery cells 4 and prevents the battery cells 4 from falling out. The end face plate 13T has an electrode window 20 that opens up a part of the cell end face 6. The electrode window 20 guides the connection tab 8T provided on the lead plate 8 and connects to the cell electrode on the cell end face 6. The cell holder 13 allows the battery cells 4 to be inserted into the respective insertion parts of one cell holder 13A, and the other cell holder 13B to be stacked, fitted, and locked onto the cell holder 13A to position the battery cells 4 in place.

[0034] The core pack 2 shown in the cross-sectional view of Figure 3 and the enlarged cross-sectional view of Figure 4 has the upper battery unit 3A and the lower battery unit 3B positioned on both sides of the internal duct 9, vertically in the figures. The upper and lower battery units 3A and 3B have the discharge end face 6A and non-discharge end face 6B of the battery cells 4 positioned opposite each other vertically in the internal duct 9. The core pack 2 can also arrange the discharge end face 6A and non-discharge end face 6B of adjacent battery cells 4 alternately in the longitudinal direction of the internal duct 9, but the core pack 2 shown in Figures 2 and 3 connects two adjacent rows of battery cells 4 in parallel, with two discharge end faces 6A and two non-discharge end faces 6B arranged alternately. The core pack 2 shown in the figures above connects two adjacent battery cells 4 in parallel, but the core pack 2 can also arrange multiple discharge end faces 6A and multiple non-discharge end faces 6B alternately. (Lead plate 8)

[0035] The lead plate 8 is a metal plate connected to the positive and negative terminals of adjacent battery cells 4, connecting the battery cells 4 in series or parallel. The lead plate 8 can be positioned in a fixed location on the cell holder 13 using a mating structure. The lead plate 8 is laminated to a lead plate 8X by laminating a heat insulating plate 12 on its surface. The heat insulating plate 12 can be bonded to the surface of the lead plate 8 via adhesive or bonding material. The structure of bonding the heat insulating plate 12 to the lead plate 8 prevents relative misalignment between the heat insulating plate 12 and the lead plate 8. However, although not shown in the diagram, since the heat insulating plate 12 and the lead plate 8 can be positioned in a fixed location on the cell holder 13 using a mating structure, the heat insulating plate 12 does not necessarily have to be bonded to the lead plate 8. For example, it can be positioned in a fixed location on the cell holder 13 using a mating structure and laminated to the lead plate 8 without misalignment.

[0036] The heat-insulating board 12 is laminated on the surface of the lead plate 8 and can be made of an insulating material, preferably an inorganic board, that has heat-resistant properties to withstand the high temperature and high pressure emissions discharged from the battery cell 4. Mica can be used as the inorganic board material. Mica can be used as a thin heat-insulating board 12 with excellent heat-resistant properties. However, all other insulating materials with excellent heat-resistant properties, such as glass or enamel, can also be used as the heat-insulating board 12 instead of mica.

[0037] Figure 4 is an enlarged cross-sectional view of the internal duct 9 located between the upper and lower battery units 3A and 3B. In this figure, the internal duct 9 has heat insulating plates 12 laminated on each lead plate 8 connected to the battery cells 4 which are arranged in opposing positions at the top and bottom. The heat insulating plates 12 are laminated on the lead plates 8 to form a laminated lead plate 8X. Figure 4 shows the internal duct 9 located between the upper and lower laminated lead plates 8X. The laminated lead plates 8X are arranged in opposing positions on both sides of the internal duct 9 (opposite positions at the top and bottom in the figure), with the area covering the discharge end face 6A of the battery cell 4 being designated as a discharge permeable area 8A with a discharge permeable opening 11, and the area covering the non-discharge end face 6B being designated as a discharge dispersion and occlusion area 8B without a discharge permeable opening 11.

[0038] The lead plates 8 in the permeable region 8A are connected to the cell electrodes on the cell end face 6 by connection tabs 8T. In the dispersion-blocking region 8B, the lead plates 8 do not have permeable openings 11 for discharge in the heat-insulating board 12, and the laminated lead plates 8X and the cell end face 6 are kept in a non-contact state, with an air layer 22 between them and the cell end face 6. In the enlarged cross-sectional view of the dispersion-blocking region 8B shown in Figure 4, the laminated lead plates 8X of the dispersion-blocking region 8B do not have permeable openings 11 in either the lead plate 8 or the heat-insulating board 12, and an air layer 22 is provided between the lead plate 8 and the non-discharge end face 6B.

[0039] The laminated lead plate 8X shown in the exploded perspective views of Figures 9 and 10 has a structure in which neither the lead plate 8 nor the heat insulating plate 12 has a permeable opening 11 in the dispersed occlusion region 8B of the heat insulating plate 12, i.e., in the position opposite to the non-discharge end face 6B of the battery cell 4. As shown in the enlarged cross-sectional view of Figure 4, this laminated lead plate 8X can cover the non-discharge end face 6B of the battery cell 4 with both the lead plate 8, which does not have a permeable opening 11, and the heat insulating plate 12. However, although not shown, the dispersed occlusion region 8B of the lead plate 8 can also be structured in which the lead plate 8 has a permeable opening 11, but the heat insulating plate 12 does not have a permeable opening 11.

[0040] As shown in the enlarged cross-sectional view of Figure 4, in the dispersed blockage region 8B, the structure in which an air layer 22 is provided between the laminated lead plate 8X and the cell end face 6, without permeable openings 11 in both the lead plate 8 and the heat insulating plate 12, has the advantage that the lead plate 8 and the cell end face 6 of the battery cell 4 are not thermally coupled, and thermal runaway of the battery cell 4 located opposite the discharge end face 6A can be more effectively prevented. The structure in which an air layer 22 is provided between the lead plate 8 and the cell end face 6 in the dispersed blockage region 8B prevents the lead plate 8 in the dispersed blockage region 8B from connecting to the cell electrodes of the battery cell 4.

[0041] The battery unit 3 requires that both the positive and negative electrodes of the battery cells 4 be electrically connected to the lead plates 8 and connected in series or parallel. The schematic connection diagram in Figure 14 illustrates a state in which the battery cells 4 are connected in parallel and series without connecting the lead plates 8 to the cell electrodes at both ends of the battery cell 4. The cylindrical battery cell 4 has an outer metal casing that is sealed by insulating the opening with a sealing plate, with the outer casing acting as the negative electrode and the center of the sealing plate acting as the positive electrode. In this battery cell 4, the opening edge of the top surface of the outer casing is crimped and the opening of the outer casing is sealed with a sealing plate. An insulating material is placed between the outer casing and the sealing plate to insulate them. In this structure of the battery cell 4, the entire outer casing acts as the negative electrode, so the lead plates 8 that connect to the negative electrode do not necessarily need to be connected to the cell end face 6, i.e., the bottom surface of the outer casing. In the connection diagram in Figure 14, the core pack 2 connects the lead plates 8 to the outer casing that is exposed at the outer edge of the sealing plate. This core pack 2 allows all battery cells 4 to be connected in series or parallel using the lead plates 8, without connecting the dispersed blockage regions 8B of the lead plates 8, which are located on both sides of the internal duct 9, to the cell electrodes.

[0042] As shown in the enlarged cross-sectional view of Figure 11, the lead plate 8 can also be connected to the cell electrode of the non-discharge end face 6B of the battery cell 4 at the lead plate 8 in the dispersed blockage region 8B. In this figure, the lead plate 8 in the dispersed blockage region 8B is connected to the cell electrode of the battery cell 4, and a planar heat insulating plate 12 is laminated on the lead plate 8 in the dispersed blockage region 8B. The dispersed blockage region 8B of the lead plate 8 shown in this figure is provided with a protrusion 23 that projects toward the cell end face 6 of the battery cell 4 without providing a transparent opening 11, and the protrusion 23 can be locally connected to the cell end face 6 by a method such as laser welding. In this laminated lead plate 8X, the protrusion 23 of the lead plate 8 is connected to the cell electrode, and a planar heat insulating plate 12 is laminated on the surface of the lead plate 8 so as to close the opening of the protrusion 23, and an air layer 22 is provided between the protrusion 23 and the heat insulating plate 12. The battery pack 1, in which the lead plates 8 of the distributed occlusion region 8B are connected to the cell electrodes, has the advantage of simplifying the connection between the lead plates 8 and the battery cells 4, as shown in the connection diagram of Figure 15. This is because it is not necessary to connect the lead plates 8 to the cell negative electrodes located on the outer edge of the sealing plate of the battery cell 4.

[0043] The battery unit 3, which has unit electrode surfaces 7 on both its upper and lower surfaces, ejects waste material from the top and bottom of the battery unit 3 in Figure 3, so the core pack 2 ejects waste material from both the top and bottom. The battery pack 1, which houses this battery unit 3 in a case 5, has surface ducts 10 on the top and bottom of the core pack 2 to discharge the waste material ejected from the top and bottom of the core pack 2 to the outside of the case 5. The battery pack 1 has an internal duct 9 inside the case 5, and a surface duct 10 between the top and bottom of the core pack 2 and the inner surface of the case 5, so that the waste material ejected from the top and bottom of the battery unit 3 can be discharged to the outside of the case 5.

[0044] Figures 12 and 13 show enlarged cross-sectional views of the surface duct 10. Figure 12 is an enlarged cross-sectional view of the upper surface duct 10A that discharges waste materials discharged upward from the core pack 2 to the outside of the case 5. In Figure 12, a heat-resistant plate 17 is placed on the inner surface of the case 5, and the upper surface duct 10A is provided between the heat-resistant plate 17 and the laminated lead plate 8X. Figure 13 is an enlarged cross-sectional view of the lower surface duct 10B that discharges waste materials discharged downward from the core pack 2 to the outside of the case 5. In Figure 13, a heat-resistant plate 17 is placed on the inner surface of the case 5, and the lower surface duct 10B is provided between the heat-resistant plate 17 and the laminated lead plate 8X.

[0045] The battery pack 1 described above allows the inner spacing (d) of the internal duct 9, which is positioned between the battery units 3, to be less than twice that of the surface duct 10. This is because, while the surface duct 10 receives waste from one side, the internal duct 9 discharges waste from both battery units 3 to the outside of the case 5. Therefore, the inner spacing (d) of the internal duct 9 needs to be wider than that of the surface duct 10. However, since the internal duct 9 does not have an insulating plate 12 in the middle, the inner spacing (d) of the internal duct 9 can be made less than twice that of the surface duct 10, thereby preventing the induction of thermal runaway. Thus, the core pack 2 has the advantage of being able to prevent the induction of thermal runaway by reducing the outer dimensions of the case 5 while still providing surface ducts 10 above and below it. [Industrial applicability]

[0046] The battery pack of this disclosure can be suitably used in all applications where a high level of safety is required. [Explanation of symbols]

[0047] 1…Battery pack 2… Core Pack 3, 3A, 3B... Battery Units 4…Battery cell 5...Case; 5A...Upper case, 5B...Lower case 6...Cell end face; 6A...Discharge end face, 6B...Non-discharge end face 7... Unit electrode surface 8...Lead plate; 8X...Laminated lead plate 8A…Transmission area 8B…Distributed occlusion area 8T…Connection tab 9…Internal duct 10, 10A, 10B... Surface duct 11…Transmission aperture 12…Insulating board 13, 13A, 13B... Cell holder 13T…End plate 14…Insulating spacer 15... Circuit board 16…Circuit board assembly 17… Heat-resistant plate 18… Lead wire 20… Electrode window 22...Air layer 23...Protruding part

Claims

1. A battery unit consisting of multiple battery cells, It comprises a case that houses multiple of the aforementioned battery units, The aforementioned battery cell is One cell end face serves as the discharge end face for waste, and the other cell end face serves as the non-discharge end face that does not eject waste. The aforementioned battery unit Multiple of the aforementioned battery cells are arranged in a parallel position with their end faces on the same plane to form a unit electrode surface. A lead plate, to which the battery cell is connected, is arranged on the unit electrode surface. The aforementioned case is, An internal duct is provided inside the case to discharge the waste ejected by the battery cell to the outside. The unit electrode surfaces of the battery unit are arranged on both sides of the internal duct. The aforementioned internal duct is The discharge end face and the non-discharge end face of the battery cell are arranged at opposing positions on both sides. The aforementioned lead plate is Arranged on both sides of the aforementioned internal duct, The region covering the discharge end face of the battery cell is defined as a permeable region for discharged material, with a permeable opening formed therein. The region covering the non-discharge end face of the battery cell is configured as a dispersion and blockage region for the discharged material ejected from the permeable opening. Furthermore, the lead plate is At least one heat insulating plate is laminated on the surface of the dispersed blockage region, The heat insulating plate, which is laminated in the aforementioned dispersed blockage region, A battery pack having a structure that reflects the discharged material ejected from the permeable opening into the internal duct onto its surface and disperses it within the internal duct.

2. A battery pack according to claim 1, The transparent region of the lead plate is A battery pack connected to the cell end face of the discharge end face.

3. A battery pack according to claim 1, The dispersed occlusion region of the lead plate is A battery pack in which the battery cells are not connected to the cell end faces, and an air layer is provided between the battery pack and the cell end faces.

4. A battery pack according to claim 1, The aforementioned battery cell A battery pack having a cell positive electrode provided on the discharge end face.

5. A battery pack according to claim 1, The transparent opening of the lead plate is A battery pack having through holes provided in the lead plate.

6. A battery pack according to claim 1, A battery pack in which the inner spacing (d) of the internal ducts is 4 mm or more.

7. A battery pack according to claim 1, A battery pack in which the aforementioned heat insulating board is made of an inorganic plate material.

8. A battery pack according to claim 7, A battery pack in which the aforementioned heat insulating plate is made of mica.

9. A battery pack according to claim 1, The aforementioned battery unit A battery pack comprising a plurality of battery cells, the discharge end faces of which are arranged adjacent to each other in the longitudinal direction of the internal duct.

10. A battery pack according to claim 1, The aforementioned case is, The internal duct is arranged between the battery units, The case is provided with a surface duct located between the inner surface of the case and the surface of the core pack, A battery pack in which the inner spacing (d) of the internal ducts is less than twice that of the surface ducts.

11. A battery pack according to claim 1, The aforementioned battery cell is a cylindrical battery, A sealing plate for a cylindrical battery is placed on the discharge end face. The non-discharge end face is the battery pack, which is the bottom surface of the cylindrical battery casing.

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