Rectangular power storage device

Abstract

The present invention provides a rectangular power storage device capable of preventing difficult discharge of gas due to clogging of a safety valve by fragments of an electrode body or the like when a spike test is performed. A rectangular power storage device is provided with: a rectangular box-shaped case having a case main body and a rectangular plate-shaped cover body; an electrode body accommodated in the housing; a positive electrode terminal member that passes through a positive electrode insertion hole provided in the cover body and extends and protrudes to the outside; and a negative electrode terminal member that passes through the negative electrode insertion hole, extends and protrudes to the outside, and has: a first safety valve that is provided in the center region of the cover body and opens under a first operating pressure; a second relief valve which is provided on one side of the central region and which opens at a second operating pressure higher than the first operating pressure; and a third relief valve which is provided on the other side of the central region and which opens at a third operating pressure higher than the first operating pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to a square-shaped power storage device that houses an electrode body in a rectangular box-shaped case made of metal and is sealed. BACKGROUND

[0002] For a secondary battery such as a lithium ion secondary battery (hereinafter, also simply referred to as a battery) that houses an electrode body in a rectangular box-shaped metal case, a so-called nail penetration test is sometimes performed, which is configured to pierce a metal rod into the central portion of the largest main side face among six faces that form the case in a manner that penetrates the positive electrode plate and the negative electrode plate that are stacked in the housed electrode body, to observe the behavior of the battery, such as confirming the operation of a safety valve provided to the case. The nail penetration test is performed to confirm that the safety valve provided to the case also operates in a situation where the main side face of the case collides with another component and crushes the case and the electrode body due to an accident of a vehicle on which the battery is mounted, and a short circuit occurs in the electrode body, and further abnormal heat generation and gas generation occur, causing an increase in internal pressure. In addition, in the nail penetration test described above, the position at which the metal rod is pierced is set to be near the center of the main side face of the case because the main side face has a large area and thus has low strength, and the center of the main side face has low strength and is easily deformed by a large amount of crushing, which further causes a short circuit in the electrode body.

[0003] As an example of a battery provided with such a safety valve, for example, Patent Literature 1 can be cited. The battery of Patent Literature 1 houses an electrode body in a rectangular box-shaped case made of metal. The case is composed of a bottomed square tubular case main body and a lid having a rectangular plate shape elongated in the longitudinal direction and sealing a rectangular opening portion of the case main body. The safety valve is provided to the substantially central portion in the longitudinal direction between the positive electrode terminal portion provided to one side in the longitudinal direction and the negative electrode terminal portion provided to the other side in the lid having the rectangular plate shape elongated in the longitudinal direction.

[0004] Patent Literature 1: Japanese Patent Application Laid-Open No. 2017-117750

[0005] However, when gas is generated and the safety valve is opened in a situation where the nail penetration test described above is performed, it is found that fragments of the positive electrode plate, the negative electrode plate, and the like of the electrode body formed due to cracking in the electrode body are scattered toward the safety valve together with the gas flowing toward the safety valve, and the safety valve is clogged by the fragments and the like, which causes the gas to be insufficiently released from the safety valve. SUMMARY

[0006] The present application is achieved in view of the problem and insight, and provides a square-shaped power storage device capable of inhibiting gas from being easily released due to the safety valve being clogged by electrode body fragments or the like in a case where the safety valve needs to be opened in a case where a short circuit occurs in an electrode body, abnormal heat generation occurs, and gas is generated.

[0007] (1) One technical solution of the present application for solving the above problem is a square-shaped power storage device including: an outer case of a rectangular parallelepiped box shape having a bottomed square cylinder-shaped outer case main body made of metal and a rectangular plate-shaped lid body made of metal and closing a rectangular opening portion of the outer case main body; an electrode body accommodated and sealed in the outer case and having a positive electrode current collecting portion and a negative electrode current collecting portion; a positive electrode terminal member having one end connected to the positive electrode current collecting portion, passing through a positive electrode insertion hole provided in one side in a long side direction in the lid body, and extending and protruding to the outside of the outer case; and a negative electrode terminal member having one end connected to the negative electrode current collecting portion, passing through a negative electrode insertion hole provided in the other side in the long side direction in the lid body, and extending and protruding to the outside of the outer case, wherein the lid body has: a first safety valve provided in a central region in the long side direction between the positive electrode insertion hole and the negative electrode insertion hole and opened at a first working pressure; a second safety valve provided at a position closer to the one side in the long side direction than the central region and opened at a second working pressure higher than the first working pressure; and a third safety valve provided at a position closer to the other side in the long side direction than the central region and opened at a third working pressure higher than the first working pressure.

[0008] In the square-shaped power storage device, the central region in the long side direction of the lid body between the positive electrode insertion hole and the negative electrode insertion hole in the lid body is provided with the first safety valve having a relatively low working pressure. Therefore, when the inner pressure of the outer case rises due to abnormal heat generation caused by a short circuit in the electrode body and gas generation, the first safety valve having a low working pressure is first opened due to the rise in the inner pressure, and the internal gas is released to the outside. In this way, the rise in the inner pressure of the battery can be inhibited. Further, since the first safety valve is provided in the central region close to the center portion of the main side surface where a short circuit is likely to occur, the generated gas can be easily and quickly released to the outside.

[0009] Further, in the square-shaped power storage device, a second safety valve and a third safety valve that open at a higher operating pressure than the first safety valve are provided at positions on one side and the other side of the central region in the long side direction. Therefore, along with the gas flow toward the first safety valve that has opened, electrode body fragments are scattered toward the first safety valve, and even in the case where the first safety valve is clogged by the fragments and the like and cannot release gas and the internal pressure rises again, by the opening of at least either one of the second safety valve and the third safety valve, the internal pressure can be prevented from rising again. Further, since two safety valves, the second safety valve and the third safety valve, are provided, by the opening of at least either one, the possibility of preventing the internal pressure from rising again can be improved.

[0010] Further, the second safety valve is provided at a position on one side of the central region in the long side direction where the first safety valve is provided. In addition, the third safety valve is provided at a position on the other side of the central region. Therefore, compared to the first safety valve, the second and third safety valves are farther apart from the portion of the main side surface of the case into which the metal rod is inserted in the nail penetration test, and thus compared to the first safety valve, it is more difficult for the scattered electrode body fragments to reach the second and third safety valves.

[0011] Further, the second safety valve and the third safety valve open later than the first safety valve, and thus it can be considered that most of the electrode body fragments have already been scattered toward the first safety valve. From this point, it is also difficult for the electrode body fragments to reach the second and third safety valves. Thus, it is difficult for the second and third safety valves to be clogged by the electrode body fragments.

[0012] Further, as the square-shaped power storage device, a lithium ion secondary battery, a secondary battery such as a sodium ion secondary battery, a power storage device such as a lithium ion capacitor, and the like can be given.

[0013] In addition, in the present application, the central region in the long side direction in the cover refers to a range of 30% of the entire length of the cover in the long side direction, centered on the center in the long side direction.

[0014] As the electrode body housed in the case, a flat-wound electrode body can be used, or a laminated electrode body can be used. For the positive electrode current collecting portion that connects the positive electrode terminal member, and the negative electrode current collecting portion that connects the negative electrode terminal member, in the flat-wound electrode body, a portion in which the exposed positive electrode current collecting foil and the negative electrode current collecting foil overlap in a spiral shape can be given. In addition, in the flat-wound electrode body and the laminated electrode body, a portion in which the exposed positive electrode current collecting foil and the negative electrode current collecting foil protrude in a tab shape can be considered as the positive electrode current collecting portion and the negative electrode current collecting portion.

[0015] (2) On the basis of the square-shaped power storage device described in (1), the second safety valve can be provided at a position on the one side in the long side direction than the positive electrode insertion hole.

[0016] (3) In the square-shaped power storage device described in (1) or (2), the third safety valve can be provided at a position on the other side in the longitudinal direction than the negative electrode insertion hole.

[0017] In the square-shaped power storage device, the second safety valve is provided at a position on the one side in the longitudinal direction than the positive electrode insertion hole, that is, at a position on the outer side in the longitudinal direction than the positive electrode insertion hole. In addition, the third safety valve is provided at a position on the other side in the longitudinal direction than the negative electrode insertion hole, that is, at a position on the outer side in the longitudinal direction than the negative electrode insertion hole. In the square-shaped power storage device, if the first safety valve is clogged by the electrode body fragments and the like after that, the second safety valve or the third safety valve is opened, and thus gas flows toward the second safety valve or the third safety valve that is opened, and the electrode body fragments can fly toward the second safety valve or the third safety valve together with the gas. However, in the square-shaped power storage device, the positive electrode terminal member or the negative electrode terminal member is present midway to the second safety valve or the third safety valve. The positive electrode terminal member or the negative electrode terminal member functions as a blocking member that stops the flying fragments from reaching the second safety valve or the third safety valve by catching the flying fragments. In this way, in the square-shaped power storage device, it is possible to further reduce the risk of the second safety valve and the third safety valve being clogged by the fragments. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a longitudinal sectional view of A-A in the battery according to Embodiment 1. Figure 2 is a longitudinal sectional view of A-A in the battery according to Embodiment 1.

[0019] Figure 2 is a plan view of the battery according to Embodiment 1.

[0020] Figure 3 is a longitudinal sectional view of B-B in the battery according to Embodiment 2. Figure 4 is a longitudinal sectional view of B-B in the battery according to Embodiment 2.

[0021] Figure 4 is a plan view of the battery according to Embodiment 2.

[0022] EXPLANATION OF REFERENCE NUMERALS

[0023] 1, 101…Battery (square energy storage device); 2…Electrode body; 2pc…Positive current collector; 2nc…Negative current collector; 4…Outer casing; 6, 106…Cover; LH…(Cover)long side direction; LH1…(long side direction)one side; LH2…(long side direction)the other side; 6CA, 106CA…Central area; 6p, 106p…Positive insertion hole; 6n, 106n…Negative insertion hole; 6s1, 106s1…First safety valve; 6s2, 106s2…Second safety valve; 6s3, 1 06s3…Third safety valve; P1…First working pressure; P2…Second working pressure; P3…Third working pressure; 7, 107…Positive terminal component; 7C, 107C…Internal connection part of positive electrode; 7I, 107I…Intermediate part of positive electrode; 7G, 107G…External terminal part of positive electrode; 8, 108…Negative terminal component; 8C, 108C…Internal connection part of negative electrode; 8I, 108I…Intermediate part of negative electrode; 8G, 108G…External terminal part of negative electrode; 9p, 9n, 109p, 109n…Terminal insulation component. Detailed Implementation

[0024] (Implementation Method 1)

[0025] The following is a reference. Figure 1 , Figure 2 The following describes battery 1 (an example of the square energy storage device of the present invention) as a lithium-ion secondary battery according to Embodiment 1. This battery 1 is a square and sealed lithium-ion secondary battery, used in various devices such as hybrid vehicles, plug-in hybrid vehicles, battery electric vehicles (BEVs), and drones. Furthermore, the width direction AH, thickness direction BH, and height direction CH of battery 1 are set as follows: Figure 1 , Figure 2 The direction is indicated by arrows in the diagram.

[0026] The battery 1 of this embodiment comprises a square outer casing 4 that is thinner in the thickness direction BH, an electrode body 2 that is housed and sealed inside the outer casing 4, and an electrolyte 3 that is housed in the outer casing 4 and impregnated with the electrode body 2. The outer casing 4 is made of metal (aluminum in this embodiment 1) and is a cuboid box shape, having a bottomed rectangular cylindrical outer casing body 5 and a cover 6 welded to the rectangular opening 5o of the outer casing body 5 to seal the rectangular opening 5o. The electrode body 2 is covered inside the outer casing 4 by a rectangular bag-shaped insulating film 10. In addition, the electrolyte 3 described above is contained inside the outer casing 4, part of which is impregnated inside the electrode body 2, and the other part is accumulated at the bottom of the outer casing 4.

[0027] The electrode body 2 housed within the outer casing 4 is a known so-called flat wound electrode body, with a strip-shaped positive electrode plate 2P and a strip-shaped negative electrode plate 2N wound around a pair of strip-shaped separators 2S, and along the... Figure 1The thickness direction BH orthogonal to the paper surface is pressed to be flattened. The electrode body 2 is housed in the case 4 in a posture in which it is laid down and the winding axis 2X extends in the width direction AH.

[0028] The strip-shaped positive electrode plate 2P in the electrode body 2 is one in which a positive electrode current collector foil composed of an aluminum foil is layered with positive electrode active material layers on both surfaces. The positive electrode active material layers are composed of positive electrode active material particles, conductive particles, and a binder. In the present embodiment, as the positive electrode active material particles, for example, lithium transition metal complex oxide particles such as lithium nickel cobalt manganese complex oxide particles are used. Further, the positive electrode current collector foil exposed at the end portion of the strip-shaped positive electrode plate 2P in the width direction one side (leftward in Figure 1 the drawing) is layered in a spiral shape to become a positive electrode current collecting portion 2pc.

[0029] On the other hand, the strip-shaped negative electrode plate 2N in the electrode body 2 is one in which a negative electrode current collector foil composed of a copper foil is layered with negative electrode active material layers on both surfaces. The negative electrode active material layers are composed of negative electrode active material particles and a binder. In the present embodiment, as the negative electrode active material particles, graphite particles are used. Further, the negative electrode current collector foil exposed at the end portion of the strip-shaped negative electrode plate 2N in the width direction other side (rightward in Figure 1 the drawing) is layered in a spiral shape to become a negative electrode current collecting portion 2nc.

[0030] The electrolyte 3 is a nonaqueous electrolyte having an organic solvent, and a lithium salt containing fluorine as a supporting salt. In the present embodiment, as the organic solvent, an organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate are mixed is used. Further, as the lithium salt containing fluorine, LiPF6 is used. The salt concentration of the lithium salt in the electrolyte 3 at the time of injection is 1.1 M.

[0031] The cover 6 in the case 4 is a rectangular plate shape elongated in the long direction LH (in Figure 1 , Figure 2 the drawing, the left-right direction coinciding with the width direction AH), and a rectangular positive electrode insertion hole 6p is provided in the long direction LH one side LH1 (in Figure 1 , Figure 2 the drawing, the left direction), and a rectangular negative electrode insertion hole 6n is also provided in the long direction LH other side LH2 (in Figure 1 , Figure 2 the drawing, the right direction). Further, in the cover 6, an injection port 6i is also provided. In the present embodiment 1, specifically, the injection port 6i is provided between the negative electrode insertion hole 6n and a first safety valve 6s1 described later. This injection port 6i is hermetically closed by an injection plug 11 after injection of the electrolyte 3.

[0032] In addition, when a range of 30% of the entire length of the lid 6 centered on the center 6C in the long direction LH is set as the central region 6CA, the first safety valve 6s1 is provided in the central region 6CA. In detail, in a portion of the central region 6CA closer to one side LH1 (on the left in Figure 1 , Figure 2 the embodiment 1, the first safety valve 6s1 is provided in a range of 30% of the entire length of the lid 6 centered on the center 6C in the long direction LH. In detail, in a portion of the central region 6CA closer to one side LH1 (on the left in

[0033] the embodiment 1, the first safety valve 6s1 is provided in a range of 30% of the entire length of the lid 6 centered on the center 6C in the long direction LH. In detail, in a portion of the central region 6CA closer to one side LH1 (on the left in

[0034] the embodiment 1, the first safety valve 6s1 is provided in a range of 30% of the entire length of the lid 6 centered on the center 6C in the long direction LH. In detail, in a portion of the central region 6CA closer to one side LH1 (on the left in

[0035] The working pressures P2 and P3 depend on the magnitude of the working pressure P1 and the strength of the housing 4, but can be selected within the range of 1.05 to 2.0 times the working pressure P1. Considering the deviation of the working pressures of each safety valve, a value of 1.05 times or more is preferred in order to reliably open the first safety valve 6s1 first. On the other hand, this is because, in the event that the first safety valve 6s1 is blocked by debris, in order to quickly open the second safety valve 6s2 or the third safety valve 6s3 before the internal pressure of the housing 4 becomes too high, a value of 2.0 times or less is preferred. In addition, in this embodiment 1, the working pressures P2 and P3 are set equally, but the working pressures P2 and P3 can also be different, that is, the working pressure P2 can be lower than the working pressure P3 (P2 < P3), or the working pressure P3 can be lower than the working pressure P2 (P3 < P2).

[0036] In this embodiment 1, the three safety valves 6s1, 6s2, and 6s3 of the cover 6 are stamped together with the cover 6 formed by stamping sheet metal. Alternatively, the cover 6 may be configured such that mounting holes (not shown) for the safety valves are pre-drilled in the cover 6, and a separately formed safety valve component is airtightly fixed in the mounting holes by welding or bonding.

[0037] A positive terminal component 7, formed by bending an aluminum plate, is inserted through the positive electrode insertion hole 6p of the cover body 6. This positive terminal component 7 is insulated from the cover body 6 by a terminal insulating component 9p and is fixedly mounted to the cover body 6. The positive terminal component 7 consists of a rectangular flat positive electrode external terminal portion 7G surrounded by the terminal insulating component 9p and exposed externally, and one end of the electrode body 2 (located in...). Figure 1 It consists of a positive electrode internal connection part 7C connected to the positive electrode current collector part 2pc (at the left end), and a positive electrode middle part 7I connecting these parts.

[0038] Similarly, a negative terminal component 8, formed by bending a copper plate, is inserted into the negative electrode insertion hole 6n of the cover body 6. This negative terminal component 8 is insulated from the cover body 6 by a terminal insulating component 9n and is fixedly mounted to the cover body 6. The negative terminal component 8 consists of a rectangular flat negative electrode external terminal portion 8G surrounded by the terminal insulating component 9n and exposed externally, and a terminal portion 8G located at the other end of the electrode body 2 (in...). Figure 1 The electrode body 2 is composed of a negative electrode internal connection part 8C connected to the negative electrode current collector part 2nc (located at the right end), and a negative electrode intermediate part 8I connecting these parts. Thus, the electrode body 2 is fixed and held to the cover body 6 via the positive terminal component 7 and the negative terminal component 8.

[0039] The battery 1 is formed by covering the electrode body 2 fixed to the lid 6 via the positive terminal member 7 and the negative terminal member 8 with the rectangular bag-shaped insulating film 10, and inserting the electrode body 2 into the case main body 5, and hermetically welding and sealing the rectangular opening portion 5o of the case main body 5 and the peripheral portion 6F of the lid 6 to form the case 4. Further, the liquid electrolyte 3 is injected into the case 4 through the injection port 6i, and a portion of the liquid electrolyte 3 is immersed in the electrode body 2, and the injection port 6i is sealed with the injection plug 11. After that, after initial charging, high-temperature aging, and inspection, and the like are performed, the battery 1 is completed.

[0040] Further, for the battery 1 after completion and before shipment, and the battery 1 after shipment and use, a nail penetration test is sometimes performed. The nail penetration test is performed to confirm that, in the case where the battery 1 collides with other members and is crushed due to an accident of a vehicle in which the battery 1 is mounted, and a short circuit occurs in the electrode body 2, and further abnormal heat generation and gas generation occur to cause an increase in internal pressure, the safety valve provided in the case 4 also operates to suppress the increase in internal pressure. Further, in the nail penetration test, the position of the penetration metal rod NL is set to the central portion (center 4MC) of the major side surface 4M having the largest area and facing the thickness direction BH in the rectangular case 4. The reason for this setting is that the major side surface 4M has a large area in the case 4, and thus the strength is low, and the strength around the center 4MC in the major side surface 4M is low, and thus a large crushing deformation easily occurs, and further a short circuit in the electrode body 2 occurs.

[0041] For example, as the nail penetration test, the metal rod NL made of stainless steel having a thickness of 3 mm and a sharp semispherical tip is penetrated into the center 4MC of the major side surface 4M of the battery 1 at SOC 100% and battery temperature 60°C to form a state in which a portion of the electrode body 2 is penetrated. In this way, in the penetration portion of the electrode body 2, the positive electrode plate 2P and the negative electrode plate 2N are brought into a short-circuited state, a large current flows, and abnormal heat generation occurs, and in addition to evaporation of the organic solvent forming the liquid electrolyte 3, evaporation of each of the positive electrode plate 2P, the negative electrode plate 2N, and the separator 2S occurs, and gas is generated to cause an increase in internal pressure of the case 4. In this case, if the internal pressure of the case 4 exceeds the operation pressure PI of the first safety valve 6sl, the first safety valve 6sl is opened, and gas is discharged from the first safety valve 6sl to the outside to suppress the increase in internal pressure.

[0042] However, for example, as indicated by a dashed line in Figure 1 , sometimes a crack 2K occurs in the electrode body 2 from the vicinity of the penetration metal rod NL. In this case, there is a possibility that fragments of the positive electrode plate 2P, the negative electrode plate 2N, and the separator 2S forming the electrode body 2 are scattered toward the first safety valve 6sl by the gas flow GF1 toward the first safety valve 6sl, the first safety valve 6sl is blocked by the fragments, and the gas cannot be discharged through the first safety valve 6sl, and thus the internal pressure is increased again.

[0043] In this regard, in the battery 1 of the present embodiment 1, the second safety valve 6s2 and the third safety valve 6s3 that open at an operating pressure P2, P3 higher than the operating pressure PI of the first safety valve 6sl are further provided. By opening of at least any one of the two second safety valve 6s2 and the third safety valve 6s3, the re-increase in the internal pressure can be suppressed. Further, the two safety valves of the second safety valve 6s2 and the third safety valve 6s3 are provided to increase the possibility of suppressing the re-increase in the internal pressure.

[0044] Further, the second safety valve 6s2 is provided outside the central region 6CA where the first safety valve 6sl is provided, i.e., at a position closer to the one side LHl of the longitudinal direction LH than the central region 6CA. In addition, the third safety valve 6s3 is provided at a position closer to the other side LH2 of the central region 6CA. Thus, the second safety valve 6s2 and the third safety valve 6s3 are farther apart from the inserted metal rod NL than the first safety valve 6sl. Therefore, it is more difficult for the fragments of the flying electrode body 2 to reach the second safety valve 6s2 and the third safety valve 6s3 than the first safety valve 6sl, and thus it is difficult for the second safety valve 6s2 and the third safety valve 6s3 to be clogged by the fragments of the electrode body 2.

[0045] Further, the second safety valve 6s2 or the third safety valve 6s3 is delayed in opening after the opening of the first safety valve 6sl, and thus it is considered that most of the fragments of the electrode body 2 have already flown toward the first safety valve 6sl. From this point, it is also difficult for the fragments of the electrode body 2 to reach the second safety valve 6s2 and the third safety valve 6s3, and thus it is less likely for the second safety valve 6s2 and the third safety valve 6s3 to be clogged by the fragments.

[0046] Further, as described above, in the battery 1, if the second safety valve 6s2 or the third safety valve 6s3 opens after the first safety valve 6sl is clogged by the fragments of the electrode body 2 or the like, and if gas flows toward the opened second safety valve 6s2 or the third safety valve 6s3, it is still possible for the fragments of the electrode body 2 to fly toward the second safety valve 6s2 or the third safety valve 6s3 along with the gas flow GF2, GF3.

[0047] However, in the battery 1 of the present embodiment 1, the second safety valve 6s2 is provided at a position closer to the one side LHl of the longitudinal direction LH than the positive electrode insertion hole 6p, i.e., at a position outside the positive electrode insertion hole 6p in the longitudinal direction LH. Similarly, the third safety valve 6s3 is provided at a position closer to the other side LH2 of the longitudinal direction LH than the negative electrode insertion hole 6n, i.e., at a position outside the negative electrode insertion hole 6n in the longitudinal direction LH. Thus, by observing the above, it is considered that the second safety valve 6s2 and the third safety valve 6s3 are less likely to be clogged by the fragments of the electrode body 2 than the first safety valve 6sl. Figure 1As can be seen, in the middle of the flow of the gas flow GF2 toward the second safety valve 6s2, that is, toward one side LH1 of the longitudinal direction LH, there is the positive electrode terminal member 7 connected to the positive electrode current collecting portion 2pc of the electrode body 2, specifically, the positive electrode intermediate portion 71 thereof. Also, toward the third safety valve 6s3, in the middle of the flow of the gas flow GF3 toward the other side LH2 of the longitudinal direction LH, there is the negative electrode intermediate portion 81 of the negative electrode terminal member 8 connected to the negative electrode current collecting portion 2nc of the electrode body 2.

[0048] Therefore, even if the fragments of the electrode body 2 are scattered toward the second safety valve 6s2 or the third safety valve 6s3, the fragments are easily caught in the positive electrode intermediate portion 71, the negative electrode intermediate portion 81. That is, the positive electrode intermediate portion 71 of the positive electrode terminal member 7, the negative electrode intermediate portion 81 of the negative electrode terminal member 8 also function as a blocking member that prevents the fragments from reaching the second safety valve or the third safety valve. In this way, in the battery 1 of the present embodiment 1, the risk of the second safety valve 6s2 or the third safety valve 6s3 also being clogged by the fragments of the electrode body 2 can be further reduced.

[0049] (Embodiment 2)

[0050] Hereinafter, while referring to Figure 3 , Figure 4 , a description will be given of the battery 101 (an example of a secondary battery) as a lithium-ion secondary battery to which the present embodiment 2 is applied. The battery 101 is a square and airtight lithium-ion secondary battery like the battery 1 to which the present embodiment 1 is applied, but differs in the arrangement of the second safety valve 106s2 and the third safety valve 106s3 and the like. Therefore, the description of the same parts is omitted or simplified, and a description will be given focusing on the different parts. Also, the width direction AH, the thickness direction BH, and the height direction CH of the battery 101 are described as the directions indicated by arrows in Figure 3 , Figure 4 .

[0051] The battery 101 of the present embodiment 2 also consists of a square and thin housing 4 in the thickness direction BH, an electrode body 2 housed inside the housing 4, and an electrolyte 3 housed in the housing 4 and partially impregnated into the electrode body 2. The cuboid box-shaped housing 4 has a housing main body 5 and a lid body 106 different from the lid body 6 of the present embodiment 1 that seals a rectangular opening portion 5o of the housing main body 5.

[0052] The lid body 106 of the present embodiment 2 in the housing 4 is the same as the lid body 6, and is also a rectangular plate shape elongated in the longitudinal direction LH, and has a rectangular positive electrode insertion hole 106p opened in one side LH1 of the longitudinal direction LH (in the left direction in Figure 3 , Figure 4 , Figure 3 , Figure 4The negative electrode insertion hole 106n is formed in the rectangular shape in the right direction.

[0053] In this embodiment 2, the positive electrode insertion hole 106p is formed in the rectangular shape in the right direction. Figure 4 In this embodiment 2, the positive electrode insertion hole 106p is formed in the rectangular shape in the right direction. Figure 2 As can be seen, the positive electrode insertion hole 106p of the lid 106 of this embodiment 2 is disposed on one side LH1 (outer side) in the long direction LH, as compared with the positive electrode insertion hole 6p of the lid 6 of the first embodiment. In addition, the negative electrode insertion hole 106n of the lid 106 of this embodiment 2 is disposed on the other side LH2 (outer side) in the long direction LH, as compared with the negative electrode insertion hole 6n of the lid 6 of the first embodiment.

[0054] On the other hand, the first safety valve 106s1 of the lid 106 is disposed in the same position as the first safety valve 6s1 of the lid 6, that is, in the central region 106CA. In detail, the first safety valve 106s1 is disposed in the position closer to one side LH1 (in the left direction) than the center 106C in the central region 106CA. The first safety valve 106s1 is a pressure relief type safety valve of the non-reset type that opens at the working pressure PI. Figure 3 、 Figure 4 In this embodiment 2, the first safety valve 106s1 is disposed in the position closer to one side LH1 (in the left direction) than the center 106C in the central region 106CA. In detail, the first safety valve 106s1 is disposed in the position closer to one side LH1 (in the left direction) than the center 106C in the central region 106CA. The first safety valve 106s1 is a pressure relief type safety valve of the non-reset type that opens at the working pressure PI.

[0055] In this embodiment 2, the first safety valve 106s1 is disposed in the position closer to one side LH1 (in the left direction) than the center 106C in the central region 106CA. In detail, the first safety valve 106s1 is disposed in the position closer to one side LH1 (in the left direction) than the center 106C in the central region 106CA. The first safety valve 106s1 is a pressure relief type safety valve of the non-reset type that opens at the working pressure PI.

[0056] Further, a third safety valve 106s3 is provided outside the central region 106CA of the lid 106, i.e., at a position on the other side LH2 than the central region 106CA. More specifically, the third safety valve 106s3 is provided at a position on the other side LH2 than the central region 106CA but on the inner side (one side LH1) than the negative electrode insertion hole 106n. This third safety valve 106s3 is identical to the third safety valve 6s3 of Embodiment 1, and is a non-reset type and a pressure relief type safety valve that opens at a working pressure P3 (P3 > PI, P3 = 1.1 PI) higher (e.g., 10% higher) than the working pressure PI of the first safety valve 106s1. Further, in this Embodiment 2, the working pressure P2 of the second safety valve 106s2 and the working pressure P3 of the third safety valve 106s3 are also set to be equal (PI < P2 = P3). The three safety valves 106s1, 106s2, 106s3 of the lid 106 of this Embodiment 2 are also formed by press molding together with the press molding of the lid 106 from a sheet material.

[0057] In the positive electrode insertion hole 106p of the lid 106, a positive electrode terminal member 107 formed by bending an aluminum sheet is inserted, insulated via a terminal insulating member 109p, and fixed to the lid 106. The positive electrode terminal member 107 is composed of a rectangular flat plate-shaped positive electrode outer terminal portion 107G surrounded by the terminal insulating member 109p and exposed to the outside, a positive electrode inner connecting portion 107C connected to the positive electrode current collecting portion 2pc of the electrode body 2, and a positive electrode intermediate portion 107I connected between the positive electrode outer terminal portion 107G and the positive electrode inner connecting portion 107C and extending in the height direction CH.

[0058] Further, also in the negative electrode insertion hole 106n of the lid 106, a negative electrode terminal member 108 formed by bending a copper sheet is inserted, insulated via a terminal insulating member 109n, and fixed to the lid 106. The negative electrode terminal member 108 is composed of a rectangular flat plate-shaped negative electrode outer terminal portion 108G surrounded by the terminal insulating member 109n and exposed to the outside, a negative electrode inner connecting portion 108C connected to the negative electrode current collecting portion 2nc of the electrode body 2, and a negative electrode intermediate portion 108I connected between the negative electrode outer terminal portion 108G and the negative electrode inner connecting portion 108C and extending in the height direction CH.

[0059] In the battery 101 of Embodiment 2, as in the battery 1 of Embodiment 1, if the nail penetration test is performed in which the metal rod NL is penetrated at the center 4MC of the major side 4M, the positive electrode plate 2P and the negative electrode plate 2N become in a short-circuit state at the penetration portion of the electrode body 2, a large current flows, abnormal heat generation occurs, gas is generated, and the internal pressure of the case 4 rises. At this time, if the internal pressure of the case 4 exceeds the operating pressure PI of the first safety valve 106sl, the first safety valve 106sl is opened, and the gas is released to the outside, so that the rise in the internal pressure is suppressed.

[0060] However, for example, as indicated by a dotted line in Figure 3 , a crack 2K is sometimes generated in the electrode body 2 starting from the vicinity of the penetrated metal rod NL. In this case, there is a possibility that the pieces of the electrode body 2 are scattered toward the gas flow GF1 toward the first safety valve 106sl, the first safety valve 106sl is clogged by the pieces, and the gas cannot be released from the first safety valve 106sl, so that the internal pressure rises again.

[0061] In this regard, in the battery 101 of Embodiment 2, the second safety valve 106s2 and the third safety valve 106s3 that are opened at operating pressures P2, P3 higher than the operating pressure PI of the first safety valve 106sl are provided. By opening at least any one of the two second safety valve 106s2 and the third safety valve 106s3, the rise in the internal pressure can be suppressed again. Further, the two safety valves, the second safety valve 106s2 and the third safety valve 106s3, are provided to increase the possibility of suppressing the rise in the internal pressure again.

[0062] Further, in Embodiment 2, the second safety valve 106s2 and the third safety valve 106s3 are provided outside the central region 106CA, that is, at positions on the one side LH1 and the other side LH2 of the central region 106CA in the longitudinal direction LH. Therefore, the distance from the inserted metal rod NL to the second safety valve 106s2 and the third safety valve 106s3 is longer than the distance from the metal rod NL to the first safety valve 106sl. Therefore, compared with the first safety valve 106sl, it is more difficult for the pieces of the electrode body 2 that are scattered to reach the second safety valve 106s2 and the third safety valve 106s3, so that clogging by the pieces of the electrode body 2 is less likely to occur.

[0063] Further, the second safety valve 106s2 or the third safety valve 106s3 is opened later than the first safety valve 106sl, so it is considered that most of the pieces of the electrode body 2 have already been scattered toward the first safety valve 106sl. From this point, it is difficult for the pieces of the electrode body 2 to reach the second safety valve 106s2 and the third safety valve 106s3, so that clogging by the pieces is difficult to occur.

[0064] The application has been described based on Embodiments 1 and 2, but the application is not limited to the embodiments, and it is needless to say that the application can be appropriately changed and applied without departing from the gist thereof.

[0065] For example, in Embodiment 1, as shown in FIG. 1, the second safety valve 6s2 and the third safety valve 6s3 smaller than the first safety valve 6s1 are used, but if the installation site can be ensured, the same size as the first safety valve 6s1 can be used. In addition, the second safety valve 6s2 and the third safety valve 6s3 are made to have the same shape and size, but can have different shapes and sizes. Figure 2

[0066] In addition, in Embodiments 1 and 2, an example of the battery 1 in which the electrode body 2 in which the strip-shaped positive electrode plate 2P and the strip-shaped negative electrode plate 2N are wound with a pair of strip-shaped separators 2S interposed therebetween and become a flat one flat-wound type electrode body is housed in the case 4 is shown. However, the application can also be applied to a battery in which a laminated electrode body in which a plurality of paper-shaped positive electrode plates and negative electrode plates are alternately stacked with a paper-shaped separator interposed therebetween is housed in a case. In addition, the application can also be applied to a battery in which a plurality of electrode bodies, for example, three flat-wound type electrode bodies are housed in a case.​

Claims

1. A square-shaped energy storage device, comprising: The rectangular box-shaped shell has a bottomed square cylindrical shell body made of metal and a rectangular plate-shaped cover made of metal that closes the rectangular opening of the shell body. The electrode body is contained and sealed within the outer casing, and has a positive current collector and a negative current collector. A positive terminal component, one end of which is connected to the positive current collector, passes through a positive insertion hole located on one side of the cover along its longitudinal direction, and extends protruding outward from the outer casing; and The negative terminal component is connected at one end to the negative current collector, passes through the negative insertion hole located on the other side of the long side in the cover, and extends outward from the outer shell. in, The cover has: The first safety valve is located in the central region along the long side between the positive electrode insertion hole and the negative electrode insertion hole, and opens under the first working pressure. The second safety valve is located on the side of the central region that is closer to the long side, and opens at a second working pressure that is higher than the first working pressure. as well as The third safety valve is located on the other side of the central region along the long side, and opens at a third working pressure that is higher than the first working pressure.

2. The square energy storage device according to claim 1, wherein, The second safety valve is located on the side of the positive electrode insertion hole that is closer to the long side.

3. The square energy storage device according to claim 1 or 2, wherein, The third safety valve is located on the other side of the long side, which is closer to the negative electrode insertion hole.

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