Battery pack

Abstract

The present invention prevents a reduction in safety caused by a high-temperature exhaust gas injected from an open exhaust valve.　This pack battery is accommodated in a battery case (2) by connecting a heat-resistant cap (8) to an end of a battery block in which battery cells (1) each having an exhaust valve on an end surface thereof are arranged in a plurality of rows. In the battery block, a valve-side end surface (1a) of the battery cell (1) is disposed at a first end portion to which the heat-resistant cap (8) is connected. The heat-resistant cap (8) includes: a closing plate (31) that is provided with a first discharge gap (15A) between the closing plate (31) and a battery block end surface (10a); a peripheral wall (32) that is connected to the circumference of the closing plate (31) and is provided with a second discharge gap (15B) between the peripheral wall (32) and a battery block outer periphery; and a partition wall (33) that is disposed between adjacent battery cell end surfaces, and partitions the first discharge gap (15A) into the end surfaces of each battery cell (1), wherein the exhaust gas discharged to the valve-side end surface (1a) passes through a discharge gap (15) including the first discharge gap (15A) and the second discharge gap (15B) and is discharged to the outside from an exhaust opening.

Description

[Technical field]

[0001] The present invention relates to a battery pack having a rechargeable battery built into a battery case. [Background technology]

[0002] In recent years, there has been an increasing demand for higher output from battery packs used as power sources for electrical equipment, and non-aqueous electrolyte secondary batteries such as lithium-ion batteries, which have excellent efficiency per unit volume, are being adopted. Although lithium-ion batteries have high output, their internal pressure can increase for some reason. To ensure safety against an increase in the battery's internal pressure, a vent valve is provided that opens at a set pressure to prevent the battery from bursting (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-211909 A Summary of the Invention [Problem to be solved by the invention]

[0004] The exhaust valve opens when the internal pressure is higher than the set pressure, but in this state the battery is in an abnormally heated state, and high-temperature gas is forcefully ejected from the open exhaust valve. It is difficult for a battery pack containing such battery cells to safely eject the high-temperature exhaust gas ejected forcefully from the battery cells to the outside. In particular, the exhaust gas ejected from the exhaust valve of a lithium-ion battery, which is a non-aqueous electrolyte secondary battery, is abnormally hot at over 400°C and ejected forcefully, so there are various problems when the exhaust gas is ejected to the outside at a high temperature. Furthermore, the extremely hot exhaust gas ejected from the exhaust valve of the battery cell heats other battery cells inside the battery case, causing thermal runaway. Inducing thermal runaway inside the battery case dramatically increases the thermal energy generated, impairing safety.

[0005] The present invention was developed with the objective of preventing the above-mentioned problems, and its main object is to provide a battery pack which prevents a decrease in safety due to high-temperature exhaust gas being sprayed through an open exhaust valve. [Means for solving the problem]

[0006] A battery pack according to one embodiment of the present invention includes a battery block in which battery cells are arranged in multiple rows, each having an end face with a vent valve that opens when the internal pressure exceeds a set pressure, a heat-resistant cap connected to an end face of the battery block, and a battery case housing the battery block and having an exhaust opening for exhausting exhaust gas from the vent valve to the outside of the case. The battery block has a valve-side end face with the vent valve of the battery cell disposed at a first end portion to which the heat-resistant cap is connected. The heat-resistant cap includes a closing plate disposed with a first exhaust gap between it and the end face of the battery block, a peripheral wall connected to the periphery of the closing plate and disposed with a second exhaust gap between it and the outer periphery of the battery block, and a partition wall disposed between the end faces of the adjacent battery cells on the end face side of the battery block of the closing plate and partitioning the first exhaust gap between the end faces of the respective battery cells, so that exhaust gas exhausted to the valve-side end face of the battery cell passes through the exhaust gap consisting of the first exhaust gap and the second exhaust gap and is exhausted to the outside from the exhaust opening. Effect of the Invention

[0007] The battery pack of the present invention can enhance safety by suppressing the harmful effects of high-temperature exhaust gas ejected from the exhaust valves of the battery cells. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view of a battery pack according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of the battery pack shown in FIG. [Diagram 3] FIG. 3 is an exploded perspective view of the battery pack shown in FIG. 2. [Figure 4] 4 is a cross-sectional view taken along line IV-IV of the battery pack shown in FIG. [Diagram 5] 5 is a cross-sectional view of the battery pack shown in FIG. 4 along line VV. [Figure 6] 6 is a cross-sectional view taken along line VI-VI of the battery pack shown in FIG. [Figure 7] FIG. 2 is an exploded perspective view showing a heat-resistant cap and a battery block. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The battery pack of the first embodiment of the present invention comprises a battery block in which battery cells are arranged in multiple rows, the battery blocks having exhaust valves on their end faces that open when the internal pressure exceeds a set pressure, a heat-resistant cap connected to the end of the battery block, and a battery case housing the battery block and having an exhaust opening for exhausting exhaust gas from the exhaust valve to the outside of the case. The battery block has a valve-side end face on which the exhaust valve of the battery cell is provided, located at a first end to which the heat-resistant cap is connected. The heat-resistant cap comprises a closing plate arranged to provide a first exhaust gap between itself and the end face of the battery block, a peripheral wall connected to the periphery of the closing plate and arranged to provide a second exhaust gap between itself and the outer periphery of the battery block, and a partition wall arranged between the end faces of the adjacent battery cells on the end face side of the battery block of the closing plate and partitioning the first exhaust gap between the end faces of the respective battery cells, so that exhaust gas exhausted to the valve-side end face of the battery cells passes through the exhaust gap consisting of the first exhaust gap and the second exhaust gap, and is exhausted to the outside from the exhaust opening.

[0010] The above battery pack ensures high safety by eliminating the adverse effects of high-temperature exhaust gas ejected from an open exhaust valve. This is because the above battery pack can collide the high-temperature exhaust gas ejected from the exhaust valve against a heat-resistant cap to attenuate its energy and also control the flow direction to exhaust the gas. This feature is because the above battery pack has a first end of a battery block in which battery cells are arranged in multiple rows, which serves as the valve-side end face on which the exhaust valves of the battery cells are provided, a heat-resistant cap is connected to this end, a closing plate is arranged on this heat-resistant cap with a first exhaust gap provided between it and the end face of the battery block, a peripheral wall is provided around the closing plate and a second exhaust gap is provided between this peripheral wall and the outer periphery of the battery block, and a partition is provided between the end faces of the adjacent battery cells on the side of the end face of the battery block, which partitions the second exhaust gap for each end face of the battery cells, and exhaust gas that is ejected onto the valve-side end face of the battery cells is ejected through the first exhaust gap and the second exhaust gap. In particular, in the above battery pack, when a specific battery cell arranged at the end of the battery block experiences thermal runaway and emits high-temperature exhaust gas, the exhaust gas emitted from the end face is emitted into a first exhaust gap partitioned by a partition wall and guided to a second exhaust gap. This heat-resistant cap guides the high-temperature exhaust gas from the first exhaust gap to the second exhaust gap, attenuating its energy and emitting it, but does not allow it to flow to the end face of an adjacent battery cell that is not experiencing thermal runaway. In particular, high-temperature exhaust gas exceeding 400°C immediately after being emitted is vented to the outside without being allowed to flow to the end face of an adjacent battery cell that is not experiencing thermal runaway. This prevents the induction of thermal runaway in the battery cells, while attenuating and venting both the kinetic energy and thermal energy of the exhaust gas to the outside.

[0011] Furthermore, the above battery pack has the advantage that assembly is simple and can be mass-produced efficiently, because heat-resistant caps can be attached to the battery blocks to prevent thermal runaway and attenuate the energy of exhaust gases before discharging them to the outside.

[0012] In a battery pack according to a second embodiment of the present invention, the battery block is equipped with a battery holder in which battery cells are arranged in fixed positions, and a second ejection gap is provided between the peripheral wall and the battery holder.

[0013] In a battery pack of the third embodiment of the present invention, the battery holder and battery case are made of plastic, the heat-resistant cap is made of a plastic with a higher heat resistance than the battery holder and battery case, and the closing plate, peripheral wall and partition are molded into a single unitary structure out of plastic.

[0014] In a battery pack according to a fourth embodiment of the present invention, the heat-resistant cap is made of fiber-reinforced plastic reinforced with heat-resistant fiber.

[0015] In a battery pack according to a fifth embodiment of the present invention, the heat-resistant fibers are inorganic fibers.

[0016] In a battery pack according to a sixth embodiment of the present invention, the battery block has a lead plate that connects adjacent battery cells at the end face of the first end, and the leading edge of the partition wall contacts the surface of the lead plate.

[0017] A battery pack according to a seventh embodiment of the present invention has cylindrical battery cells, and a battery pack according to an eighth embodiment of the present invention has partitions disposed in valleys formed on the outer periphery of adjacent cylindrical batteries.

[0018] A battery pack according to a ninth embodiment of the present invention uses non-aqueous electrolyte secondary batteries as its battery cells, and a battery pack according to a tenth embodiment of the present invention uses lithium ion batteries as its battery cells.

[0019] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper", "lower", and other terms including these terms) are used as necessary, but the use of these terms is for the purpose of facilitating 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. In addition, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or members. Furthermore, the embodiments shown below are specific examples of the technical ideas of the present invention, and do not limit the present invention to the following. Furthermore, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative and not to limit the scope of the present invention, unless otherwise specified. Furthermore, the contents described in one embodiment or example can be applied to other embodiments or examples. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

[0020] (Embodiment 1) The battery pack 100 shown in Figs. 1 to 6 has a battery block 10 in which battery cells 1 are arranged in multiple rows housed in a battery case 2. The battery case 2 is made up of a lower case 2A, which is a first case, and an upper case 2B, which is a second case that is connected to the first case and closes the opening of the first case. The battery block 10 in Figs. 2 to 5 has multiple battery cells 1 arranged in two rows and four stages on the same plane. In the battery block 10, two rows of battery cells 1 are arranged in fixed positions in battery holders 4 to form battery assemblies 11, and multiple battery assemblies 11 are connected in multiple stages in the longitudinal direction. A heat-resistant cap 8 is connected to the end of the battery block 10. The heat-resistant cap 8 controls the flow direction of the high-temperature exhaust gas ejected from the exhaust valve of the battery cells 1 to attenuate the energy, and further guides the exhaust gas to an exhaust opening to safely exhaust it outside the battery case 2.

[0021] (Battery cell 1) Battery cell 1 is a cylindrical battery with a discharge valve on the valve-side end face 1a that opens when the internal pressure exceeds a set pressure. A cylindrical battery contains electrodes and electrolyte in a cylindrical metal case. The metal case has a sealed structure with a sealing plate hermetically fixed to the opening of a cylindrical exterior can that closes the bottom. The exterior can is manufactured by pressing a metal plate into a cylindrical shape. The sealing plate is hermetically fixed by crimping to the periphery of the opening of the exterior can via an insulating packing.

[0022] Although not shown, the battery cell 1 has a discharge valve on the sealing plate to prevent the internal pressure of the metal case from becoming abnormally high and causing damage, and the sealing plate side is the valve side end face 1a. The battery cell 1 has an opening for the discharge valve on the sealing plate, which opens to discharge internal gases and the like. However, the battery cell 1 can also have a discharge valve and its opening on the bottom, which is the end face opposite the sealing plate, without providing an opening for the discharge valve on the sealing plate of the outer can, and use the bottom as the valve side end face. The discharge valve opens when the internal pressure exceeds a set pressure, for example 1.5 MPa, to prevent the metal case from being destroyed by the rise in internal pressure. If the battery cell 1 becomes abnormal, for example due to an internal short circuit, the discharge valve opens to prevent rupture. In this state, the temperature of the battery cell 1 is also very high, so the gas and electrolyte (ejected material) discharged from the opened discharge valve are abnormally hot. In particular, in a battery pack in which the battery cells 1 are non-aqueous electrolyte secondary batteries such as lithium ion batteries, the temperature of the exhaust gas reaches abnormally high temperatures of 400°C or more. Furthermore, because lithium ion batteries are filled with a non-aqueous electrolyte, if they are discharged from the case at a high temperature, they may come into contact with oxygen in the air and ignite, causing the temperature to rise even further. Not only in lithium ion batteries, but also in other batteries, the exhaust valve opens in an abnormal state, so the exhaust gas ejected from the exhaust valve reaches an abnormally high temperature. Therefore, in order to maintain a high level of safety, it is extremely important that the exhaust gas ejected from the open exhaust valve be exhausted to the outside of the case after attenuating its energy.

[0023] (Battery block 10) The battery block 10 shown in Figs. 2 to 6 has a heat-resistant cap 8 connected to a first end 10A, which is one end of the battery block 10. In the battery block 10, the valve-side end faces 1a of the battery cells 1 are arranged at the first end 10A. In the battery block 10 in which the battery cells 1 are arranged in multiple rows, the valve-side end faces 1a of all the battery cells 1 are arranged at the first end 10A, or the valve-side end face 1a of any one of the battery cells 1 is arranged at the first end 10A, and exhaust gas is ejected from the first end 10A of the battery block 10. The battery block 10 in Fig. 3 connects multiple battery assemblies 11 in the longitudinal direction. This battery block 10 has exhaust gaps 12 between each battery assembly 11 to exhaust exhaust gas. The battery block 10 in Fig. 3 connects four battery assemblies 11 in the longitudinal direction, and therefore has three rows of exhaust gaps 12. Each exhaust gap 12 is disposed between adjacent battery assemblies 11, and disperses and exhausts exhaust gas discharged from the battery cells 1 of each battery assembly 11 to the surroundings.

[0024] In the battery assemblies 11, the battery cells 1 are arranged in fixed positions in the battery holder 4 and are arranged in two rows. The battery holder 4 is made of thermoplastic plastic molded into a shape that fits the battery cells 1 and arranges them in fixed positions. The plastic of the battery holder 4 is preferably an engineering plastic with excellent heat insulating properties, such as polycarbonate. The battery holder 4 in FIG. 3 arranges the battery cells 1 in two rows in a position that extends in the longitudinal direction of the battery case 2. The battery block 10 in the figure is connected in four stages, with exhaust gaps 12 for exhaust gas between the battery assemblies 11. The battery blocks 10 connect the battery cells 1 in series or parallel with lead plates (not shown) arranged in the exhaust gaps 12. The battery block 10 in the figure arranges the battery assemblies 11, each consisting of two rows of battery cells 1, in four rows in the longitudinal direction, and connects eight battery cells 1 in series and parallel in the four two rows. The battery pack 100 shown in the figures has battery blocks 10 arranged in four stages inside a battery case 2, with battery assemblies 11 consisting of two rows of battery cells 1 connected together, but the number of battery cells 1 housed in the case and the connection state of the battery pack of the present invention are not limited to the structure shown in the figures.

[0025] Exhaust gap 12 is a gap that guides exhaust gas ejected from the exhaust valve to the outside, and connects battery cells 1 of battery assembly 11 with lead plates 13. Exhaust gap 12 is, for example, 1 mm to 5 mm wide, and diffuses exhaust gas ejected from the exhaust valve on the end face of battery cell 1 to the surrounding area.

[0026] (Battery case 2) Battery case 2 is made of a thermoplastic plastic such as polycarbonate, has a long, narrow box shape overall, and houses battery block 10 and circuit board 3 connected to battery block 10. Polycarbonate used for battery case 2 and battery holder 4 can withstand temperatures from low to high and has excellent impact resistance. However, the present invention does not limit the battery holder 4 and battery case 2 to polycarbonate, and other thermoplastic resins that can be used over a wide temperature range, preferably engineering plastics, can also be used.

[0027] The battery case 2 in Figs. 1 to 4 is composed of a lower case 2A and an upper case 2B that closes the opening of the lower case 2A. The lower case 2A is groove-shaped with side walls 22 on both sides of a long and narrow rectangular bottom plate 21 in the figures, and a battery block 10 is arranged inside the side walls 22. The upper case 2B connects the outer periphery to the lower case 2A and closes the upper opening of the lower case 2A. The lower case 2A shown in Fig. 4 has both side walls 22 curved to fit the cylindrical battery. The lower case 2A has multiple exhaust openings 23 spaced apart in the longitudinal direction of the side walls 22 for exhausting exhaust gas to the outside. The battery pack 100 in the figures has a heat dissipation plate 5 arranged between the battery block 10 and the lower case 2A. The exhaust openings 23 are opened at positions facing the heat dissipation plate 5, i.e., on the outside of the heat dissipation plate 5. In this battery pack 100, exhaust gas ejected into the exhaust gap 12 can be exhausted to the outside after its energy is attenuated by the heat dissipation plate 5. The exhaust gas passes through the gap between the battery block 10 and the heat dissipation plate 5, and then passes through the gap between the heat dissipation plate 5 and the battery case 2, before being exhausted to the outside through the exhaust opening 23. A battery pack 100 having a heat dissipation plate 5 can attenuate the energy of the exhaust gas before exhausting it, ensuring even higher safety. However, the battery pack of the present invention does not necessarily require the heat dissipation plate 5 to be provided, and the exhaust gas can also be exhausted by guiding it through a gap in the case to the exhaust opening 23.

[0028] (Heat-resistant cap 8) In the battery pack 100 of Figures 2 and 3, a heat-resistant cap 8 is connected to the battery block 10 in order to attenuate and exhaust the energy of the exhaust gas ejected at the first end 10A of the battery block 10. In the battery pack 100 of the figures, a heat-resistant cap 8 is connected to the first end 10A of the battery block 10, and an end plate (not shown) integrally formed with the battery holder 4 is disposed at the other end, the second end 10B from which the lead wire 19 is drawn out. Although not shown, the end plate is configured to prevent thermal damage caused by high-temperature exhaust gas by disposing a heat insulating plate on the inside or by providing a diffusion gap for diffusing the exhaust gas. However, although not shown, the battery block 10 can be made heat-resistant by connecting heat-resistant caps 8 to both ends, and battery cells 1 can also be disposed on the end faces of the battery block 10 to which the heat-resistant caps 8 are not connected such that the valve-side end faces 1a of the battery cells 1 are not disposed.

[0029] The heat-resistant cap 8 is produced by molding a thermoplastic plastic with better heat resistance than the battery holder 4 and the battery case 2. Plastics with excellent heat resistance are produced by molding a fiber-reinforced plastic, such as PBT, which is reinforced by embedding inorganic fibers. The heat-resistant cap 8 is connected to the end of the battery block 10, and attenuates the energy of the exhaust gas ejected from the valve-side end face 1a of the battery cell 1 and changes the flow direction. The heat-resistant cap 8 shown in Figures 2 to 7 is composed of a closing plate 31 arranged opposite the battery block end face 10a, a peripheral wall 32 connected to the periphery of the closing plate 31, and a partition wall 33 arranged on the side of the closing plate 31 on the battery block end face 10a side, and the closing plate 31, the peripheral wall 32, and the partition wall 33 are molded into an integral structure.

[0030] A first exhaust gap 15A is provided between the closing plate 31 and the battery block end face 10a in order to exhaust the exhaust gas ejected from the exhaust valve. In the first exhaust gap 15A, the closing plate 31 causes the exhaust gas ejected from the exhaust valve to collide with its inner surface, attenuating its energy and further diffusing it to the surroundings. The first exhaust gap 15A provided between the closing plate 31 and the battery block end face 10a, or more precisely, between the closing plate 31 and the end face of the battery cell 1, is connected to, for example, 0.5 mm or more and 3 mm or less so as to smoothly exhaust the exhaust gas while attenuating the kinetic energy of the exhaust gas.

[0031] Exhaust gas passing through the first discharge gap 15A is diffused to the surroundings by the closing plate 31 and collides with the inside of the peripheral wall 32. A lead plate 13 fixed to the battery cell 1 is placed in the first discharge gap 15A. The lead plate 13 is fixed by welding to the end face of the battery cell 1. A welding part is provided in the center of the lead plate 13 via a slit, and a welding part is welded to the end face of the battery cell 1. The outer periphery provided outside the welding part via the slit is not welded to the end face of the battery cell 1, so that a small gap is formed without adhering to the end face of the battery cell 1. Therefore, the first discharge gap 15A is provided between the closing plate 31 and the lead plate 13, and between the lead plate 13 and the end face of the battery cell. The total width of the first discharge gap 15A formed on both sides of the lead plate 13 is preferably set to the above-mentioned range so that the exhaust gas can be smoothly discharged while passing through a narrow gap to attenuate the kinetic energy of the exhaust gas.

[0032] The peripheral wall 32 has a second discharge gap 15B between itself and the outer periphery of the battery block 10 in order to redirect the exhaust gas flowing in from the first discharge gap 15A and discharge it. The peripheral wall 32 shown in FIG. 5 causes the exhaust gas flowing in from the first discharge gap 15A to collide with itself inward to attenuate its energy, and then changes its flow direction at a right angle to the longitudinal direction of the battery cell 1 without scattering it to the surroundings. The exhaust gas collides with the inner surface of the peripheral wall 32, changes direction, attenuates its kinetic energy, and is discharged in the longitudinal direction of the battery cell 1. The peripheral wall 32 has a second discharge gap 15B between itself and the outer periphery of the battery cell 1 in order to allow the exhaust gas to flow between itself and the battery cell 1. The exhaust gas that collides with the inner side of the blocking plate 31 and flows into the second discharge gap 15B is redirected inside the partition wall 33 as shown by the arrow in the figure and is discharged in the longitudinal direction of the battery cell 1.

[0033] The partition wall 33 in FIG. 6 is fixed vertically to the inner surface of the blocking plate 31 and defines the exhaust gap 15 between the end face of the battery cell 1. The partition wall 33 defines a divided exhaust gap 15a between the valve-side end face 1a of the abnormal battery cell 1 with its exhaust valve open and the blocking plate 31, and a divided exhaust gap 15a between the adjacent battery cell 1 and the blocking plate 31. When the battery cell 1 experiences thermal runaway due to, for example, an internal short circuit, the internal pressure rises abnormally and the exhaust valve opens. In this state, the exhaust gas ejected from the exhaust valve becomes abnormally hot. If the high-temperature exhaust gas heats the adjacent battery cell 1, it causes thermal runaway to occur. The partition wall 33 prevents the high-temperature exhaust gas from flowing to the end face of the adjacent battery cell 1, thereby preventing the induction of thermal runaway. The partition wall 33 is provided to prevent the exhaust gas ejected from the abnormal battery cell 1 from heating the adjacent battery cell 1, and defines the exhaust gap 15 between the battery cells 1.

[0034] 4, the second exhaust gap 15B is wider at the top than at the bottom, allowing a larger amount of exhaust gas to be exhausted to the top. A fitting groove 4a is provided in the battery holder 4 above the second exhaust gap 15B, and the partition wall 33 is guided into this fitting groove 4a to position the partition wall 33 in a fixed position.

[0035] The partition wall 33 prevents the exhaust gas from flowing to the end face of the adjacent battery cell 1, thereby preventing the exhaust gas from heating the adjacent battery cell 1. The partition wall 33 is provided to protrude from the closing plate 31 into the first discharge gap 15A and is disposed between the end faces of the adjacent battery cells. The heat-resistant cap 8 of FIG. 5 is provided with partition walls 33 not only in the first discharge gap 15A but also in the second discharge gap 15B, and the partition walls 33 of the first discharge gap 15A and the second discharge gap 15B are formed as a single plate. This heat-resistant cap 8 can more effectively prevent the high-temperature exhaust gas from heating the adjacent battery cell 1, thereby more effectively preventing thermal damage to the adjacent battery cell 1. However, the partition wall can be provided only in the first discharge gap 15A, and a structure can be formed in which the exhaust gas is prevented from heating the end face of the adjacent battery cell 1 at the end face of the battery block 10.

[0036] 5 and 7 has a shape in which the center of the partition 33 located in the first discharge gap 15A is lowered and both ends are higher so that it extends into the second discharge gap 15B. The partition 33 protruding from the inner surface of the closing plate 31 contacts the surface of the lead plate 13 to divide the first discharge gap 15A between the battery cells 1, and the partitions 33 on both sides extend into the valleys around the outer periphery of the cylindrical battery to divide the second discharge gap 15B, which is located between the battery cells 1 and the peripheral wall 32, between the battery cells 1. In the heat-resistant cap 8 of FIG. 4, the second discharge gap 15B above the battery cell 1 is wider than the lower side in the figure, so the vertical width of the upper partition 33 is made wider than the lower side, and the lower edge of the upper partition 33 is guided into the fitting groove 4a provided in the battery holder 4. The structure that guides this partition 33 into the fitting groove 4a of the battery holder 4 has the characteristic that it can partition the second exhaust gap 15B to more reliably prevent exhaust gas from leaking, while preventing the partition 33 from shifting position, thereby more reliably preventing exhaust gas from heating the adjacent battery cell 1.

[0037] (Heat dissipation plate 5) 2 and 3 is provided with a heat dissipation plate 5 to more effectively attenuate the energy of exhaust gas. The heat dissipation plate 5 is placed inside the lower case 2A, between it and the battery block 10, and attenuates the energy of exhaust gas emitted from the battery cells 1. A plate material with better thermal conductivity than the battery case 2 is suitable for the heat dissipation plate 5. This heat dissipation plate 5 absorbs the thermal energy of the exhaust gas that it impinges on, and quickly diffuses the absorbed thermal energy over a wide area for thermal conduction to the lower case 2A, which then dissipates the thermal energy to the outside over a wide area.

[0038] A metal plate is used for the heat dissipation plate 5 as a plate material with favorable heat conduction properties. In particular, an aluminum (including aluminum alloy) plate is suitable for the heat dissipation plate 5. An aluminum plate has heat resistance, excellent heat conduction properties, and is lightweight, so it can quickly diffuse the thermal energy of exhaust gases and dissipate heat efficiently while reducing weight. In the battery pack 100 shown in the figures, the side wall 22 of the lower case 2A is shaped to fit the outer circumferential surface of the cylindrical battery, and the heat dissipation plate 5 is disposed between the side wall 22 and the battery block 10. The heat dissipation plate 5 disposed here has a flat portion that fits on the inner surface of the bottom plate 21 of the lower case 2A, and a curved portion that fits on the inside of the side wall 22 to fit the outer surface of the cylindrical battery. The battery block 10 is disposed inside the heat dissipation plate 5, and the battery block 10 has the battery cells 1 positioned in place by the battery holder 4, so the battery assembly 11 of the battery block 10 is disposed inside the heat dissipation plate 5. The inwardly curved sidewalls have a height of approximately half the thickness of the battery block 10 so that the battery block 10 can be smoothly guided into position and the inner surfaces of the sidewalls can come into contact with both sides of the battery block 10. The sidewalls come into contact with both sides of the curved battery block 10, thereby enabling efficient heat conduction from the battery block 10, but if an air layer is created between the sidewalls and the battery block 10, the air layer will impede heat conduction. This is because if the curved sidewalls are higher than half the thickness of the battery block 10, the opening width at the upper edge of the heat dissipation plate 5 will be narrower than the horizontal width of the battery block 10, making it difficult to insert the battery block 10 smoothly.

[0039] The inner surfaces of the side walls of the heat dissipation plate 5 are in surface contact with the curved surfaces on both sides of the battery block 10, and the bottom surface is in surface contact with the bottom surface of the battery block 10, thereby efficiently absorbing the thermal energy of the battery block 10. Furthermore, the outer surface of the heat dissipation plate 5 is in surface contact with the inner surface of the lower case 2A, so the absorbed thermal energy is efficiently conducted to the lower case 2A. The heat dissipation plate 5 uses an aluminum plate as a metal plate with excellent thermal conductivity, but metal plates other than aluminum, such as a copper plate, or other plate materials that are heat resistant and have excellent thermal conductivity, can also be used.

[0040] (Heat-resistant cover 6) Furthermore, a heat-resistant cover 6 is disposed on the side edge of the heat-dissipating plate 5 in a position that covers the opening of the exhaust gap 12 between the battery assemblies 11. As with the heat-dissipating plate 5, a metal plate such as aluminum, which has excellent heat resistance and thermal conductivity, is suitable for the heat-resistant cover 6. The battery pack 100 in Figs. 2 and 3 has an integrated structure in which the heat-dissipating plate 5 and the heat-resistant cover 6 are formed as a single metal plate. This structure has the characteristic that the heat-resistant cover 6 can be accurately positioned via the heat-dissipating plate 5. The heat-resistant cover 6 is folded to close the opening of the exhaust gap 12 with the battery block 10 disposed inside, so it is a bendable metal plate. The structure in which the heat-resistant cover 6 and the heat-dissipating plate 5 are formed as a single metal plate allows the heat-resistant cover 6 to be folded freely and can be positioned in an ideal position for the opening of the exhaust gap 12 of the battery block 10 without misalignment.

[0041] The heat-resistant cover 6 has a width wider than the exhaust gap 12 so that the opening of the exhaust gap 12 can be adequately covered. The width of the heat-resistant cover 6 is, for example, 1 mm or more wider than the heat-resistant cover 6, preferably 2 mm or more wider, and more preferably 3 mm or more wider. A heat-resistant cover 6 that is too wide will be difficult to bend along the surface of the cylindrical battery and close the exhaust gap 12 in an ideal state, so the width is, for example, 20 mm or less, preferably 15 mm or less. The battery pack 100 in FIG. 3 has four battery assemblies 11 connected together, so that there are three rows of exhaust gaps 12 between each battery assembly 11. The heat-resistant cover 6 closes the opening of each exhaust gap 12, so the heat-dissipating plate 5 in FIG. 3 has three rows of heat-resistant covers 6 on its side edges along the exhaust gap 12. In other words, a plurality of heat-resistant covers 6 are provided to independently close each exhaust gap 12.

[0042] The heat-resistant cover 6 can be made longer to widen the blocking area of ​​the opening of the exhaust gap 12. In the battery pack 100 of FIG. 3, the circuit board 3 is placed on the top surface of the battery block 10, and the leading edge of the heat-resistant cover 6 is made long enough to approach both side edges of the circuit board 3, and the opening of the exhaust gap 12 is covered by both the heat-resistant cover 6 and the circuit board 3. The circuit board 3 is made of a thermosetting resin such as glass epoxy and has better heat resistance than the battery case 2 made of thermoplastic resin. In the battery pack 100 of this structure, almost the entire circumference of the opening of the exhaust gap 12 is covered by the heat-dissipating plate 5, which has better heat resistance than the battery case 2, the heat-resistant cover 6, and the circuit board 3. If there is a wide gap between the heat-resistant cover 6 and the circuit board 3, exhaust gas will pass through this gap, so this gap is made as narrow as possible, for example, 2 mm or less, preferably 1 mm or less, to suppress the passage of exhaust gas.

[0043] (Circuit board 3) The circuit board 3 mounts electronic components (not shown) that are connected to the battery cells 1 and implement a protection circuit for the battery cells 1. The protection circuit is a circuit that prevents the battery cells 1 from being overcharged or overdischarged, a circuit that prevents overcurrent, or a circuit that cuts off the current when the temperature rises abnormally.

[0044] In the above-described battery pack 100, exhaust gas ejected from the exhaust valve is caused to collide with the heat-resistant cap 8, heat-dissipating plate 5, heat-resistant cover 6, and circuit board 3 to attenuate its energy, and is then diffused and discharged to the outside of the case through exhaust openings 23 provided in the lower case 2A. The exhaust openings 23 are positioned opposite the heat-dissipating plate 5 so that the exhaust gas is caused to collide with the heat-dissipating plate 5 and heat-resistant cover 6 to attenuate its energy, diffuse, and then discharged to the outside of the battery case 2. The exhaust openings 23 positioned opposite the heat-dissipating plate 5 have the heat-dissipating plate 5 on the inside, and exhaust gas diffused by the heat-dissipating plate 5 is discharged from the exhaust openings 23 to the outside of the battery case 2. The lower case 2A in FIGS. 2 and 3 has multiple exhaust openings 23 arranged at intervals in the longitudinal direction on the side wall 22 of the lower case 2A. In this battery pack 100, exhaust gas ejected into exhaust gap 12 is diffused by colliding with heat dissipation plate 5 and heat-resistant cover 6, and the diffused exhaust gas flows through gap 14 inside the case and is exhausted to the outside of battery case 2 from exhaust opening 23. A label 7 that is peeled off or melted by exhaust gas is attached to the lower case 2A so as to close the opening of exhaust opening 23. In this battery pack 100, the exhaust opening 23 is closed with label 7, preventing the intrusion of foreign matter. [Industrial Applicability]

[0045] The present invention can be effectively used in a battery pack that safely vents exhaust gases. [Explanation of symbols]

[0046] 100…Battery pack 1. Battery cell 1a...Valve side end surface 2. Battery case 2A…Lower case 2B…Upper case 3…Circuit board 4…Battery holder 4a…Mating groove 5…Heat dissipation plate 6…Heat-resistant cover 7. Label 8…Heat-resistant cap 10…Battery block 10A…First end 10a...Battery block end surface 10B...Second end 11…Battery assembly 12...Exhaust gap 13...Lead plate 14…Gap 15…Discharge gap 15A…First discharge gap 15a…Split discharge gap 15B…Second discharge gap 19…Lead wire 21…Bottom plate 22…Side wall 23...Exhaust opening 31…Blocking plate 32...peripheral wall 33…Bulkhead

Claims

1. a battery block including battery cells arranged in multiple rows, the battery cells having exhaust valves at their end faces that open when the internal pressure exceeds a set pressure; a heat-resistant cap connected to an end of the battery block; The battery block is housed in the housing, a battery case having an exhaust opening for exhausting the exhaust gas from the exhaust valve to the outside of the case; A battery pack comprising: The battery block includes: A first end portion to which the heat-resistant cap is connected, a valve side end surface of the battery cell on which the exhaust valve is provided, The heat-resistant cap is a closing plate disposed between the battery block end face and a first discharge gap; connected to the periphery of the closure plate; a peripheral wall disposed between the battery block and an outer periphery thereof and providing a second discharge gap; The battery block end face side of the closing plate, disposed between end faces of the adjacent battery cells, a partition wall that defines the first discharge gap at an end surface of each of the battery cells; a battery pack comprising: a first exhaust gap and a second exhaust gap; and a second exhaust gap configured to exhaust gas discharged to the valve side end face of the battery cell, the second exhaust gap being formed into the first exhaust gap and the second exhaust gap, and the second exhaust gap being formed into the exhaust opening.

2. 2. The battery pack according to claim 1, the battery block includes a battery holder in which the battery cells are arranged in fixed positions; The second discharge gap is a battery holder that is provided between the peripheral wall and the battery holder;

3. 3. The battery pack according to claim 2, The battery holder and the battery case are made of plastic, The heat-resistant cap is The battery holder and the battery case are made of a plastic having a higher heat resistance than the plastic. a battery pack comprising: said closing plate, said peripheral wall and said partition wall, said closing plate and said partition wall being integrally formed from plastic;

4. 4. The battery pack according to claim 3, The heat-resistant cap is A battery pack characterized in that it is made of fiber-reinforced plastic reinforced with heat-resistant fiber.

5. 5. The battery pack according to claim 4, A battery pack, wherein the heat-resistant fibers are inorganic fibers.

6. 6. The battery pack according to claim 1, The battery block is At the end surface of the first end portion, a lead plate connecting adjacent battery cells; The leading edge of the partition wall is A battery pack characterized in that it is in contact with the surface of said lead plate.

7. 7. The battery pack according to claim 1, 4. A battery pack comprising: a battery cell;

8. 8. The battery pack according to claim 7, The partition wall is A battery pack characterized in that said cylindrical batteries are disposed in valleys formed on the outer periphery of adjacent cylindrical batteries.

9. 9. The battery pack according to claim 1, 4. A battery pack comprising: a battery cell that is a non-aqueous electrolyte secondary battery;

10. 10. The battery pack according to claim 9, 4. A battery pack comprising: a battery cell that is a lithium ion battery;

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