Battery pack

Abstract

Provided is a battery pack capable of reducing adverse effects on adjacent secondary battery cells. A battery pack (100) is provided with: a plurality of secondary battery cells (1) provided with gas discharge ports (1a) on end surfaces; a battery holder (20) that holds the plurality of secondary battery cells (1); and one or more lead plates (30) that connect the end surfaces of adjacent secondary battery cells (1) among the plurality of secondary battery cells (1), the battery pack (100) being configured such that the end surfaces of the adjacent secondary battery cells (1) are arranged between the end surfaces of the adjacent secondary battery cells (1), on the surface of the battery holder (20) facing the lead plate (30) and / or the surface of the lead plate (30) facing the battery holder (20), and on the surface of the battery holder (20) facing the lead plate (30). The present invention is provided with a baffle (40) having a plurality of concavo-convex shapes, said baffle (40) generating a pressure difference in gas discharged from a secondary battery cell (1).

Description

Technical Field

[0001] The present disclosure relates to a battery pack. Background Art

[0002] In order to drive an electrical device using a rechargeable secondary battery such as a lithium ion secondary battery, a battery pack in which a plurality of secondary battery cells are housed in an outer casing is used (for example, Patent Document 1). For example, a battery pack that achieves high output and high capacity by connecting in series and parallel a plurality of secondary battery cells using cylindrical outer cans is, for example, as shown in the perspective view of Figure 9 In a state where the end faces of the cylindrical outer cans are aligned in the same planar shape, welding is performed by a flat lead plate 930 so as to cover the end faces of the outer cans of the respective secondary battery cells.

[0003] In such a battery pack, each secondary battery cell is provided with a gas discharge port for discharging high-temperature and high-pressure gas from the outer can when the inside of the outer can becomes high pressure in the event of some abnormality. For example, in a secondary battery cell using a cylindrical outer can, a gas discharge port is provided on the end face of the cylindrical outer can. In a battery pack using such secondary battery cells, when high-temperature and high-pressure gas is ejected from the gas discharge port of a certain secondary battery cell, it is required to quickly diffuse the gas and discharge the gas from the inside of the outer casing to the outside so that the high-temperature and high-pressure gas does not have an adverse effect on other normal secondary battery cells.

[0004] However, as shown in the perspective view of Figure 9 In the battery pack 900 in which the end faces of adjacent secondary battery cells are connected to each other by a lead plate 930, as shown in the cross-sectional view of Figure 10 Welding is performed in a state where the end faces of the respective secondary battery cells 901 are covered with the lead plate 930. In this state, the gas discharge port opened on the end face of the outer can is in a form covered by the lead plate 930. In this state, if high-temperature and high-pressure gas is discharged from the gas discharge port of one secondary battery cell 901, it has been found through experiments by the inventors of the present application that the following situation may occur: as shown in the cross-sectional view of Figure 11 The high-temperature and high-pressure gas discharged from the secondary battery cell 901A hits the back side of the lead plate 930 and is bounced back, and is irradiated onto the end face of the adjacent secondary battery cell 901B. In this state, the end face of the normal secondary battery cell 901B is exposed to the high-temperature and high-pressure gas. As a result, an abnormal state may occur, and there is a concern that abnormal secondary battery cells will spread.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-174673 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] One object of the present disclosure is to provide a battery pack that can reduce the adverse effects on adjacent secondary battery cells even when high-temperature and high-pressure gas is discharged from a secondary battery cell.

[0010] Means for Solving the Problems

[0011] A battery pack according to one embodiment of the present invention includes: a plurality of secondary battery cells each having a gas discharge port provided at an end face thereof; a battery holder that holds the plurality of secondary battery cells; and one or more lead plates that connect end faces of adjacent secondary battery cells among the plurality of secondary battery cells to each other. The battery pack further includes a baffle plate having a plurality of uneven shapes and generating a pressure difference for gas discharged from the secondary battery cells between the end faces of the adjacent secondary battery cells, on a surface of the battery holder facing the lead plate and / or on a surface of the lead plate facing the battery holder.

[0012] Advantages of the Invention

[0013] According to the battery pack of one embodiment of the present invention, even if high-temperature and high-pressure gas is discharged from the gas discharge port of any secondary battery cell, it is possible to avoid or suppress the situation where the gas rebounded by the lead plate connecting the end faces of adjacent secondary battery cells is transmitted to the end face of the adjacent secondary battery cell and heated by reducing the pressure of the gas by a plurality of baffle plates, thereby improving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. is a perspective view showing a battery pack according to Embodiment 1 of the present invention.

[0015] Figure 2 is Figure 1 exploded perspective view of the battery pack.

[0016] Figure 3 is a perspective view showing Figure 2 the battery module.

[0017] Figure 4 is a perspective view of the battery module viewed from the back Figure 3 the battery module.

[0018] Figure 5 is from Figure 3 the battery module with the lead plate removed exploded perspective view.

[0019] Figure 6 is fromFigure 4 Exploded perspective view of the battery module with the lead plate removed.

[0020] Figure 7 It is from Figure 5 Exploded perspective view with the battery holder further removed.

[0021] Figure 8 It is Figure 3 Cross-sectional view of the battery module at the VIII-VIII line.

[0022] Figure 9 Perspective view showing the battery pack related to the comparative example.

[0023] Figure 10 It shows Figure 9 Schematic cross-sectional view of the gas discharge port part of the battery pack.

[0024] Figure 11 It shows Figure 9 Schematic cross-sectional view of the state where the gas is reflected by the lead plate when gas is discharged from one secondary battery cell in the battery pack.

[0025] Figure 12 It is Figure 8 Enlarged perspective view of the part of the battery module surrounded by the dashed line.

[0026] Figure 13 It is Figure 12 Enlarged perspective view of the baffle.

[0027] Figure 14 It shows Figure 13 Enlarged perspective view of the flow of high-pressure gas in the baffle.

[0028] Figure 15 A is Figure 5 Side view of the battery holder, Figure 15 B is Figure 15 Enlarged cross-sectional view of the part of A surrounded by the frame, Figure 15 C is the enlarged cross-sectional view of the battery pack related to Embodiment 2, Figure 15 D is the enlarged cross-sectional view of the battery pack related to Embodiment 3, Figure 15 E is the enlarged cross-sectional view of the battery pack related to Embodiment 4, Figure 15 F is the enlarged cross-sectional view of the battery pack related to Embodiment 5.

[0029] Figure 16 Main part enlarged schematic cross-sectional view of the battery pack related to Embodiment 6.

[0030] Figure 17 Main part enlarged schematic cross-sectional view of the battery pack related to Embodiment 7.

[0031] Figure 18 is an enlarged schematic cross-sectional view of the main part of the battery pack according to Embodiment 8. Specific Embodiment

[0032] The embodiment of the present invention can also be determined by the following structures and features.

[0033] Regarding the battery pack according to another embodiment of the present invention, in the above embodiment, the plurality of baffles are arranged in parallel with each other, and a gas retention space is formed in the concave portion of the concave-convex shape. With the above structure, the high-temperature and high-pressure gas discharged from the gas outlet is respectively retained in the gas retention spaces formed between adjacent baffles, so that a pressure loss is generated every time the gas travels over the baffle, and the mass flow rate of the gas is reduced during the period until it reaches the adjacent secondary battery cells, and the effect of reducing the risk of flame spread can be expected.

[0034] In addition, regarding the battery pack according to another embodiment of the present invention, in any of the above embodiments, the plurality of baffles are fixed to the base plate, and a gap is formed by separating the end faces of the respective baffles from the inner side of the lead plate, and the gap is made narrower than the height of the baffle. With the above structure, the high-temperature and high-pressure gas discharged from the gas outlet is made to generate a pressure loss by passing through the narrow gap. In addition, the gas that has passed through the gap settles in the gas retention space, and further settles in the adjacent gas retention space by passing through the adjacent gap, and the gas travels with a pressure loss while repeating such up-and-down movement, so that the mass flow rate of the gas can be decreased as the gas travels.

[0035] Furthermore, regarding the battery pack according to another embodiment of the present invention, in any of the above embodiments, the lead plate includes: a pair of bonding pieces respectively bonded to the end faces of the adjacent secondary battery cells; and a flat portion having the pair of bonding pieces disposed on both sides thereof, the flat portion bending the pair of bonding pieces on both sides thereof so that the main surface of the flat portion is separated from the surface to which the pair of bonding pieces belong, to form a first space on the back side of the flat portion, and the plurality of baffles are arranged in the first space. With the above structure, the gas rebounded by the back surface of the flat portion of the lead plate in the first space is guided to the gas retention spaces between the baffles, so that it spreads over the plurality of gas retention spaces, thereby reducing the pressure of the gas and decreasing the mass flow rate, and thus the situation where the adjacent secondary battery cells are directly exposed to the high-temperature and high-pressure gas can be avoided or suppressed, thereby improving safety.

[0036] Furthermore, regarding the battery pack according to another aspect of the present invention, in any of the above aspects, the lead plate is provided with one or more ridges on its inner side, and each ridge is configured to intervene in the recess of the baffle. With the above structure, the exhaust path of the gas is formed in a zigzag shape by the baffle and the ridges, and an effect of increasing the pressure drop as the gas travels can be expected.

[0037] Furthermore, regarding the battery pack according to another aspect of the present invention, in any of the above aspects, the lead plate connects secondary battery cells arranged along a first direction, and the baffle extends along a second direction intersecting the first direction. With the above structure, when the high-temperature and high-pressure gas discharged from the gas discharge port of one secondary battery cell is about to reach the end face of the adjacent secondary battery cell, the baffle arranged in a posture intersecting the traveling direction of the gas obstructs the traveling, and the effect of reducing the pressure can be efficiently exerted.

[0038] Furthermore, regarding the battery pack according to another aspect of the present invention, in any of the above aspects, it further includes a battery holder that holds the plurality of secondary battery cells, and the plurality of baffles are formed on the battery holder.

[0039] Furthermore, regarding the battery pack according to another aspect of the present invention, in any of the above aspects, the outer can of the secondary battery cell is cylindrical.

[0040] Hereinafter, embodiments of the present invention will be described based on the drawings. However, the embodiments shown below are illustrative examples for embodying the technical idea of the present invention, and the present invention is not limited by the following content. In addition, the components shown in the claims are not limited to the components of the embodiments in this specification. In particular, regarding the dimensions, materials, shapes, relative configurations, etc. of the structural components described in the embodiments, unless there are particularly limiting descriptions, the main purpose is not to limit the scope of the present invention only to this, but only illustrative examples. In addition, the sizes, positional relationships, etc. of the components shown in the respective drawings may be exaggerated for clarity of explanation. Furthermore, in the following description, for the same names and symbols, the same or homogeneous components are indicated, and detailed descriptions are appropriately omitted. Further, regarding each element constituting the present invention, it is also possible to adopt a mode in which a plurality of elements are constituted by the same component, so that one component can be used in place of a plurality of elements, and conversely, the function of one component can be realized by sharing among a plurality of components.

[0041] The battery pack of the present invention can be used as a driving power source for autonomous robots for delivery, electric carts for delivery, electric scooters for golf courses, construction machinery, hybrid vehicles, electric vehicles and other vehicles. In addition, in addition to the driving power source for power-assisted bicycles, it can also be used as a power source for portable electrical equipment such as wireless devices, electric cleaners, and electric tools. Or it can also be used as a backup power source for servers, or a power supply device for home use, production service sites, and factories for stationary power storage purposes. Below, as one embodiment of the present invention, a battery pack used as a driving power source for an autonomous robot is described.

[0042] [Implementation Method 1]

[0043] exist Figures 1 - 8 1 and 2 show a battery pack 100 according to Embodiment 1 of the present invention. In these figures, respectively, Figure 1 FIG. 1 is a perspective view showing a battery pack 100 according to Embodiment 1 of the present invention. Figure 2 Shows Figure 1 An exploded perspective view of the battery pack 100, Figure 3 Shows Shows Figure 2 A perspective view of a battery module 2, Figure 4 Shown from the back Figure 3 A perspective view of a battery module 2, Figure 5 Shows from Figure 3 An exploded perspective view of the battery module 2 with the lead plate 30 removed, Figure 6 Shows from Figure 4 An exploded perspective view of the battery module 2 with the lead plate 30 removed, Figure 7 Shows from Figure 5 Further removed the battery holder 20 of the exploded perspective view, Figure 8 Shows Figure 3 1 and 2 are cross-sectional views of a battery module 2 taken along line VIII-VIII. The battery pack 100 shown in these figures includes an outer casing 10 and a battery module 2. The battery module 2 includes one or more secondary battery cells 1.

[0044] (External casing 10)

[0045] The outer casing 10 accommodates a battery module 2 composed of one or more secondary battery cells 1 and a circuit board 3. Figure 1 , Figure 2 As shown in FIG. 1 and FIG. 2 , the outer casing 10 is formed into a box-shaped rectangular shape extending in one direction when viewed from above. The box-shaped outer casing 10 has a first surface and a second surface intersecting the first surface. Figure 1 In the example of FIG. 1 , the top surface is set as the first surface, and the side surface along the length direction is set as the second surface. Figure 2As shown in the figure, inside the exterior housing 10, a storage space for storing the battery module 2 and the circuit board 3 is provided.

[0046] As Figure 2 shown, the exterior housing 10 is, for example, divided into an upper housing 11 and a lower housing 12. The obtained upper housing 11 and lower housing 12 are fixed by screwing, fitting, bonding, ultrasonic welding, etc. their corners. In addition, not limited to this structure, for example, it may be divided into a bottomed cylindrical tube portion with one side open and a lid portion for closing the open surface, or may be disassembled into three or more parts.

[0047] (Battery module 2)

[0048] In Figures 3 - 7 the figure shows the battery module 2. As shown in these figures, the battery module 2 includes a plurality of secondary battery cells 1, a battery holder 20 for storing these secondary battery cells 1, and a lead plate 30.

[0049] (Battery holder 20)

[0050] The battery holder 20 is provided with a plurality of storage cylinders 24 for storing the secondary battery cells 1 individually. In Figure 7 the example shown, in the longitudinal direction of the cylindrical secondary battery cell 1, it is divided into a first holder 21 and a second holder 22, and the secondary battery cell 1 is stored in the storage cylinders 24 from each end face in the longitudinal direction. In addition, an opening 23 is formed at the end face of the storage cylinder 24 to expose the end face of the secondary battery cell 1. Such a battery holder 20 can be made of a resin such as polycarbonate with excellent insulation.

[0051] (Secondary battery cell 1)

[0052] One or more secondary battery cells 1 can be secondary battery cells with a square or cylindrical exterior can. In Figure 7 , Figure 8 the example shown, four cylindrical secondary battery cells 1 are arranged in a posture of stacking two layers with two cells per layer. In addition, the secondary battery cells 1 are connected in series with two and in parallel with two. In addition, the number, arrangement, series or parallel connection number, etc. of the secondary battery cells are not limited to this example, and any number and arrangement can be appropriately adopted. Each secondary battery cell 1 has positive and negative electrodes. The positive and negative electrodes are preferably provided on one end face of the secondary battery cell 1. In such a secondary battery cell 1, known secondary batteries such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries can be appropriately used.

[0053] In addition, in the exterior can of the secondary battery cell 1, as Figure 8 , Figure 12 , Figure 14As shown in the figure, a gas discharge port 1a is provided. The gas discharge port 1a opens in response to an increase in the internal pressure of the outer can and discharges the gas inside the outer can to the outside. Such a gas discharge port 1a can utilize, for example, a safety valve or a sealing body provided with a cut that opens the open end.

[0054] (Lead plate 30)

[0055] A lead plate 30 is disposed on the side surface of the battery holder 20. The lead plate 30 connects the electrodes on the end faces of the secondary battery cells 1 to each other and connects the plurality of secondary battery cells 1 in series and in parallel. In Figures 3 - 7 In examples such as, the secondary battery cells 1 are connected in series with 2 and in parallel with 2, and include a first lead plate 31 that connects the end faces of 4 secondary battery cells 1 to each other and a second lead plate 32 that connects the end faces of 2 secondary battery cells 1 to each other. In addition, the number, arrangement, and series or parallel connection number of the secondary battery cells are not limited to this example, and any number and arrangement can be appropriately adopted. These lead plates 30 are made of a metal plate with excellent conductivity such as a nickel plate. In addition, an insulating plate may be disposed on the end face of the lead plate 30 as needed. The insulating plate is made of a material with excellent insulation such as paper or mica.

[0056] As Figures 3 - 7 shown, each lead plate 30 has a pair of bonding pieces 34 that are respectively bonded to the end faces of adjacent secondary battery cells 1, and a flat portion 35 that has the pair of bonding pieces 34 disposed on both sides. The flat portion 35 bends the pair of bonding pieces 34 on both sides thereof. In addition, as Figure 8 , Figure 12 shown, the main surface of the flat portion 35 is separated from the surface to which the pair of bonding pieces 34 belong, and a first space 36 is formed on the back side of the flat portion 35.

[0057] In addition, as Figure 2 shown in the exploded perspective view of, a circuit board 3 is placed on the upper surface of the battery holder 20. The battery holder 20 holds the secondary battery cells 1 and the circuit board 3. The battery module 2 is connected to the circuit board 3 via the lead plate 30. On the upper surface of the battery holder 20 that constitutes the battery module 2, a placement surface for placing the circuit board 3 is formed.

[0058] (Circuit board 3)

[0059] The battery module 2 is connected to the circuit board 3 via the lead plate 30. The circuit board 3 is equipped with a charge and discharge circuit for charging and discharging the secondary battery cells 1, a protection circuit for monitoring the voltage and temperature of the secondary battery cells 1 and cutting off the current in case of an abnormality, etc. The circuit board 3 is made of an epoxy glass substrate or the like.

[0060] (Baffle 40)

[0061] In addition, the battery pack 100 is provided with a baffle plate 40 between the end faces of adjacent secondary battery cells 1. The baffle plate 40 has a concavo-convex shape formed by a plurality of alternately arranged convex portions and concave portions. The baffle plate 40 is provided on the opposing surface of the battery holder 20 to the lead plate 30 and / or the opposing surface of the lead plate 30 to the battery holder 20, creating a pressure difference in the gas discharged from the secondary battery cell and flowing between the battery holder 20 and the lead plate 30. With such a structure, even if high-temperature and high-pressure gas is discharged from the gas discharge port 1a of any secondary battery cell, the pressure of the gas can be reduced by the baffle plate 40, thereby avoiding or suppressing the situation where the gas rebounded by the lead plate 30 connecting the end faces of adjacent secondary battery cells is transmitted to the end faces of adjacent secondary battery cells for heating, and improving safety.

[0062] That is, the inventors of the present application have found the following situation: in the structure using a lead plate for the electrical connection of secondary battery cells, the lead plate becomes the cause of the transmission of high-temperature and high-pressure gas. Specifically, in the structure using a lead plate 930 for the electrical connection of secondary battery cells 901 as in the battery pack 900 related to the comparative example shown in Figure 9 , Figure 10 a structure is adopted in which the battery holder 920 holds the end faces of a plurality of secondary battery cells 901 in an aligned posture, exposing the end faces of adjacent secondary battery cells 901, and welding is performed through the lead plate 930 for connection. In this structure, welding is performed through the flat lead plate 930 so as to cover the end faces of each secondary battery cell 901.

[0063] On the other hand, in each secondary battery cell 901, a gas discharge port 901a such as a safety valve is provided. When the inside of the outer can becomes high pressure in case of an emergency, the gas discharge port 901a opens to discharge the high-temperature and high-pressure gas inside the outer can to the outside. When high-temperature and high-pressure gas is discharged from the gas discharge port 901a, it is required to quickly discharge it to the outside of the battery pack, thereby preventing adverse effects on other normal secondary battery cells. Such a gas discharge port 901a is generally provided on the end face of the positive electrode side. As a result, as shown in the cross-sectional view of Figure 10 , the end face of the positive electrode side is in a state covered by the lead plate 930.

[0064] In this state, in case the safety valve opens at the gas discharge port 901a of any secondary battery cell 901 and high-temperature and high-pressure gas is ejected from this secondary battery cell, it has been determined through the tests of the inventors of the present application that the following situation may occur: as shown in Figure 11As shown in the schematic cross-sectional view, the high-temperature and high-pressure gas discharged from the secondary battery cell 901A hits the back side of the lead plate 930 and is bounced back, and is irradiated onto the end face of the adjacent secondary battery cell 901B. In this state, the end face of the normal secondary battery cell 901B is exposed to the high-temperature and high-pressure gas, and as a result, it will become an abnormal state, and there is a concern that the abnormal secondary battery cell will continue to spread.

[0065] Therefore, in the battery pack 100 according to the first embodiment, as Figure 8 , Figure 12 shown in the cross-sectional view, between the end faces of adjacent secondary battery cells 1, a plurality of convex portions and concave portions constituting the baffle 40 are alternately arranged. In addition, as Figure 12 , Figure 13 shown, a gap GP is formed between the upper surface of the baffle 40 and the lower surface of the lead plate 30. With such a structure, as shown by the thick arrow in the enlarged cross-sectional view of Figure 14 , even when high-pressure gas is discharged from the gas discharge port 1a of an arbitrary secondary battery cell (in Figure 14 , the left secondary battery cell 1A), the gas bounced back after colliding with the lead plate 30 will not directly reach the adjacent secondary battery cell (in Figure 14 , the right secondary battery cell 1B) due to the presence of the baffle 40, but becomes the gas that has passed through the plurality of gaps GP formed between the upper surface of the baffle 40 and the lower surface of the lead plate 30. In this way, by reducing the pressure of the gas by the baffle 40, the safety can be improved. And by diffusing the gas by the baffle 40, the mass flow rate of the gas going to the adjacent secondary battery cell can be reduced to improve safety.

[0066] In addition, according to the research of the inventors of the present application, when high-pressure gas flows into the gap GP at the right end, as it goes to the gap GP, the static pressure is converted into dynamic pressure. After passing through the gap GP, as the flow path expands, pressure recovery occurs, and the dynamic pressure is converted into static pressure, but since the air flow does not follow the flow path shape, flow separation occurs and pressure loss occurs. Moreover, by providing a plurality of alternately arranged convex portions and concave portions on the baffle 40, the above actions are repeated, and the effect of reducing the differential pressure between the inlet and the outlet of the gap GP and reducing the pressure of the gas can be exerted.

[0067] In Figure 12In examples such as this, the multiple convex portions and concave portions constituting the baffle 40 are arranged in parallel to each other. Further, in the concave portion of the baffle 40, a gas retention space GP is formed. Thus, by causing the high-temperature and high-pressure gas discharged from the gas discharge port 1a to be retained in the gas retention spaces GP formed between the baffles 40 respectively, a pressure loss is generated each time the gas travels beyond the baffle 40, and the pressure of the gas is reduced during the period until it reaches the adjacent secondary battery cell 1, and an effect of reducing the risk of flame spread can be expected.

[0068] The baffle 40 is provided on the base plate 42. In Figure 5 , Figure 8 examples such as this, the base plate 42 is the end face of the battery holder 30. Further, in Figure 14 etc., a gap GP is formed by separating the end face of each baffle 40 from the inner side of the lead plate 30. Each gap GP is shorter than the height of the baffle 40. With such a structure, the high-temperature and high-pressure gas discharged from the gas discharge port 1a passes through the narrow gap GP, thereby generating a pressure loss. In addition, the gas that has passed through the gap GP settles in the gas retention space GP, and further passes through the adjacent gap GP and settles in the adjacent gas retention space GP, and the gas travels while repeating such up-and-down movement, whereby the pressure of the gas can be decreased as the gas travels.

[0069] Further, as described above, each lead plate 30 forms a first space 36 on the back side of the flat portion 35. The baffle 40 is disposed in this first space 36. With such a structure, the gas rebounded by the back of the flat portion 35 of the lead plate 30 in the first space 36 is guided to the gas retention space GP between the flat portion 35 and the baffle 40, and is made to propagate across the multiple gas retention spaces GP, thereby reducing the pressure of the gas and decreasing the mass flow rate, and thus it is possible to avoid or suppress the situation where the adjacent secondary battery cells 1 are directly exposed to the high-temperature and high-pressure gas, thereby improving safety. Additionally, preferably, the size (PT×HT) of the gas retention space is set to a size such that the gas passing through the gap GP can form a vortex. Thus, in addition to the separation loss caused by the sudden expansion of the flow path, the pressure reduction effect can also be exerted by the frictional loss caused by the vortex. Further, preferably, the interval PT between the convex portions of the baffle 40 and the height HP are set to larger values.

[0070] In addition, the lead plate 30 connects the secondary battery cells arranged along the first direction to each other. In contrast, the concavo-convex shape of the baffle plate 40 extends along a second direction intersecting the first direction. Thus, when the high-temperature and high-pressure gas discharged from the gas discharge port 1a of one secondary battery cell 1 travels toward the end face of an adjacent secondary battery cell, the concavo-convex shape of the baffle plate 40 arranged in a posture intersecting the traveling direction of the gas obstructs the travel, and the effect of reducing the pressure can be efficiently exerted. In other words, the concavo-convex shape of the baffle plate 40 is formed in a posture intersecting the direction in which the lead plate 30 extends, and the adjacent secondary battery cells are connected to each other by the lead plate 30.

[0071] In addition, the concavo-convex shape of the baffle plate 40 is continuously formed up to the side end portions in the direction of the electrode end faces of the secondary battery cells of the first holding member 21 and the second holding member 22, respectively. Therefore, the gas travels in a direction escaping along the side surfaces in the longitudinal direction of the secondary battery cells of the first holding member 21 and the second holding member 22 due to the baffle plate 40, and is guided in a direction of being wound into a recess formed between two secondary battery cells along the side surface shape of the cylindrical secondary battery cell on the side surfaces in the longitudinal direction of the secondary battery cells of the first holding member 21 and the second holding member 22, respectively. Therefore, by reducing the mass flow rate of the gas traveling toward the adjacent secondary battery cells by the baffle plate 40, the effect of avoiding or suppressing the situation where the adjacent secondary battery cells 1 are directly exposed to the high-temperature and high-pressure gas can be improved.

[0072] For example, as Figure 3 , Figure 5 , Figure 7 shown, in an example where two secondary battery cells 1 are stacked in two layers per layer, the secondary battery cells 1 are adjacent in the up-down, left-right directions. Therefore, the first lead plate 31 connecting them is formed in a flat plate shape close to a rectangular shape extending in the up-down, left-right directions. Correspondingly, the baffle plate 40 is formed in a cross shape in the up-down, left-right directions. On the other hand, as Figure 4 , Figure 6 shown, for the second lead plate 32 connecting the left and right secondary battery cells 1, the baffle plate 40 may have a structure extending in the longitudinal direction shown in Figure 6 . In addition, in the example of Figures 3 - 7 , since the first holding member 21 and the second holding member 22 have the same shape, the baffle plate 40 is provided in a cross shape at four positions. In addition, the second holding member may have a structure in which the baffle plate is provided only in the upper center.

[0073] [Embodiments 2 to 5]

[0074] In addition, the concavo-convex shape of the cross section of the baffle plate 40 is not limited to those shown in Figure 15 A and Figure 15In addition to being rectangular as shown in B, it can also be other shapes. For example, as for the battery pack related to Embodiment 2, Figure 15 The battery holder 20C shown in C sets the concave-convex shape of the cross-section of the baffle 40C to a triangular shape. In addition, as for the battery pack related to Embodiment 3, Figure 15 The battery holder 20D shown in D sets the concave-convex shape of the cross-section of the baffle 40D to a trapezoidal shape. In addition, the concave-convex shape of the cross-section of the baffle can also be set to any polygonal shape. Further, without limiting the concave-convex shape of the cross-section of the baffle to a polygonal shape, it can also be composed of a curved surface. For example, as for the battery pack related to Embodiment 4, Figure 15 The battery holder 20E shown in E makes the concave-convex shape of the cross-section of the baffle 40E composed of a curved surface obtained by chamfering a triangular shape. Further, as for the battery pack related to Embodiment 5, Figure 15 The battery holder 20F shown in F sets the concave-convex shape of the cross-section of the baffle 40F to a fractal shape.

[0075] In addition, in the above examples, an example of forming the baffle 40 on the end face of the battery holder 20 has been described, but the present disclosure does not limit the member provided with the baffle to the battery holder. For example, a baffle can also be provided on a separator or a spacer that insulates between square secondary battery cells, or a plurality of baffles can be formed on a base plate composed of a member different from such members.

[0076] [Embodiments 6 and 7]

[0077] In addition, a baffle can also be provided on the lead plate side. Taking such examples as the battery packs related to Embodiments 6 and 7, they are respectively shown in the sectional views of Figure 16 、 Figure 17 . In these figures, for the members the same as those described in the above Embodiment 1 etc., the same reference signs are marked and the detailed description is appropriately omitted. Figure 16 、 Figure 17 The lead plates 30G and 30H shown in have second baffles 44G and 44H formed on their back sides so as to protrude into the first spaces 36G and 36H. The second baffle 44 can also be attached to the lead plate 30 by welding or the like, but preferably, as in the battery pack related to Embodiment 6 shown in Figure 16 , the second baffle 44G is attached to the lead plate 30 by integral forming. In addition, as in the battery pack related to Embodiment 7 shown in Figure 17 , the second baffle 44H can be formed by pressing or the like.

[0078] [Embodiment 8]

[0079] Further, in addition to replacing the baffle on the battery holder side and providing a second baffle on the lead plate side, it is also possible to add a second baffle on the lead plate side in addition to the baffle on the battery holder side. An example like this is shown as a cross-sectional view of the battery pack related to Embodiment 8 in Figure 18 In this figure, the same components as those described in the above Embodiment 1 etc. are also labeled with the same reference numerals, and the detailed description is appropriately omitted. Figure 18 The lead plate 30I shown in Figure 18 is provided with a plurality of ridges 44I on its inner side. Each ridge 44I is arranged to intervene in the recess of the baffle 40. With such a structure, the exhaust path of the gas is formed in a zigzag shape by the baffle 40 and the ridges 44I, and the effect of reducing the pressure as the gas travels can be further improved.

[0080] In the above example, the battery pack is assembled to an electrical device to be driven to supply power to the electrical device. In addition, when the remaining capacity of the battery pack becomes small or when the battery pack deteriorates over time, the battery pack can be replaced to continue using the electrical device. However, the present disclosure does not limit the battery pack to a replaceable type mainly containing secondary battery cells, and can also be applied to a type in which secondary battery cells are housed in the housing of the electrical device. In the present disclosure, a battery pack means that secondary battery cells are housed in a housing, and a structure in which secondary battery cells for driving are built in the housing of the electrical device itself is also called a battery pack. That is, the present disclosure is not limited to a replaceable battery pack, and can also be applied to an electrical device with built-in secondary battery cells.

[0081] Industrial Applicability

[0082] The battery pack according to the present invention can be suitably used as a driving power source for vehicles such as autonomous mobile robots for delivery, electric carts for delivery, golf courses, electric scooters, construction machinery, hybrid vehicles, and electric vehicles. In addition, in addition to the driving power source for a power-assisted bicycle, it can also be appropriately used as a power source for portable electrical devices such as wireless devices, electric cleaners, and electric tools, as a standby power source for servers for stationary energy storage applications, and as a power supply device for home, production service sites, and factories.

[0083] Description of Reference Numerals

[0084] 100... Battery pack

[0085] 1, 1A, 1B... Secondary battery cells; 1a... Gas discharge port

[0086] 2... Battery module

[0087] 3... Circuit board

[0088] 10... Outer housing

[0089] 11… Upper housing

[0090] 12… Lower housing

[0091] 20, 20C, 20D, 20E, 20F… Battery holder

[0092] 21… First holder

[0093] 22… Second holder

[0094] 23… Opening

[0095] 24… Storage cylinder

[0096] 30, 30G, 30H, 30I… Lead plate

[0097] 31… First lead plate

[0098] 32… Second lead plate

[0099] 34… Bonding piece

[0100] 35… Flat part

[0101] 36… First space

[0102] 40, 40C, 40D, 40E, 40F… Baffle

[0103] 42… Base plate

[0104] 44, 44G, 44H… Second baffle

[0105] 44I… Rib

[0106] 900… Battery pack

[0107] 901, 901A, 901B… Secondary battery cell; 901a… Gas discharge port

[0108] 920… Battery holder

[0109] GP… Gap

[0110] GP… Gas retention space

[0111] PT… Spacing between baffles

[0112] HT… Height of baffle.

Claims

1. A battery pack, comprising: A plurality of secondary battery cells, each having a gas discharge port provided at an end face; A battery holder for holding the plurality of secondary battery cells; and One or more lead plates for connecting the end faces of adjacent secondary battery cells among the plurality of secondary battery cells to each other, Between the end faces of the adjacent secondary battery cells, on the opposing surface of the battery holder to the lead plate and / or on the opposing surface of the lead plate to the battery holder, the battery pack further includes a baffle having a plurality of concavo-convex shapes that create a pressure difference for the gas discharged from the secondary battery cells.

2. The battery pack according to claim 1, wherein the concavo-convex shapes of the baffle are arranged in parallel with each other, and a gas retention space is formed in the concave portion of the concavo-convex shape.

3. The battery pack according to claim 1, wherein the baffle is provided on the base plate of the battery holder, and a gap is formed by separating the end face of each baffle from the inner side of the lead plate, and the gap is made narrower than the height of the baffle.

4. The battery pack according to claim 1, wherein the lead plate includes: A pair of bonding pieces respectively bonded to the end faces of the adjacent secondary battery cells; and A flat portion with the pair of bonding pieces disposed on both sides, The flat portion bends the pair of bonding pieces on both sides thereof, separating the main surface of the flat portion from the surface to which the pair of bonding pieces belong to form a first space on the back side of the flat portion, and the baffle is disposed in the first space.

5. The battery pack according to claim 1, wherein one or more ridges are provided on the inner side of the lead plate, and each ridge is configured to intervene in the concave portion of the baffle.

6. The battery pack according to any one of claims 1 to 5, wherein the lead plate connects the secondary battery cells arranged along a first direction to each other, and the concavo-convex shape of the baffle extends along a second direction intersecting the first direction.

7. The battery pack according to any one of claims 1 to 5, wherein the outer can of the secondary battery cell is cylindrical.

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