Secondary battery

Abstract

Provided is a sealed secondary battery in which a flow path for a gas to a relief valve covered by an insulating member is secured when the gas pressure or the gas temperature in a battery case rises to a predetermined value or more, and the relief valve is easy to operate appropriately. This secondary battery is provided with: a battery case; an electrode body accommodated in the battery case in a sealed manner; an insulating member interposed between the battery case and the electrode body; and a safety valve which is provided in the battery case at a position facing the insulating member and which is capable of discharging, to the outside of the battery case, a gas having a gas pressure or a gas temperature increased to a predetermined value or more within the battery case. The safety valve is provided with an openable valve body and a valve body supporting part which annularly supports the outer peripheral part of the valve body and is connected to the battery case, and a gas flow path forming part is provided between an insulating member pressed to the valve body side by gas and the valve body supporting part on the case inner surface of the valve body supporting part at a position closer to the inside of the case than the valve body. The gas flow path forming portion forms a gas flow path communicating with the valve body side.

Description

TECHNICAL FIELD

[0001] The technology of the present disclosure relates to a secondary battery. BACKGROUND

[0002] Generally, in a sealed secondary battery in which an electrode body is housed in a battery case, in a case where charging at a high voltage and a large current or the like is performed, gas is generated as the temperature of the battery rises, and the gas pressure or the gas temperature in the battery case can rise above a prescribed value. Therefore, in many sealed secondary batteries, a safety valve is provided in the battery case, which discharges gas in the battery case to the outside of the battery case when the gas pressure or the gas temperature in the battery case rises above the prescribed value. Also, a technology is known in which, in a case where the battery case is made of metal, an insulating member is interposed between the electrode body and the battery case for the purpose of improving the electrical insulation between the electrode body and the battery case or the like.

[0003] For example, in Patent Literature 1, a secondary battery is disclosed in which a safety valve is provided in a lid of a battery case, and an end portion of an insulating film (insulating member) interposed between an electrode body and the battery case is provided extending to the lid side. Also, in Patent Literature 2, a battery is disclosed in which an electrode group is housed in a bottomed square tubular battery case, a negative electrode lead connected to a negative electrode plate is electrically connected to an internal terminal of a sealing body having a safety valve via an upper insulating plate (insulating member), and the upper insulating plate is provided extending to a position covering the safety valve.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2020-095836

[0007] Patent Literature 2: Japanese Patent Application Publication No. 2004-31263 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, in the secondary battery of Patent Literature 1 and the battery of Patent Literature 2 described above, there is a problem in that, although the gas pressure or the gas temperature rises above the prescribed value in the battery case and gas is intended to be discharged to the outside of the battery case, the insulating member (insulating film, upper insulating plate) can hinder the flow of gas to the safety valve and the safety valve can not work properly.

[0010] The technology of the present disclosure is achieved in view of this problem, and the problem to be solved thereby is to provide a sealed secondary battery that ensures a flow path of gas to a safety valve covered by an insulating member and the safety valve easily works properly when the gas pressure or the gas temperature rises above a prescribed value in a battery case.

[0011] Means for solving the problem

[0012] (1) One form of the technology of the present disclosure for solving the above problem is a secondary battery that is a sealed secondary battery and has a battery case, an electrode body housed in the battery case in a sealed manner, an insulating member interposed between the battery case and the electrode body, and a safety valve that can discharge a gas whose gas pressure or gas temperature has risen to a prescribed value or more within the battery case to the outside of the battery case and is provided to the battery case at a position facing the insulating member, wherein the safety valve has a valve core that can open and a valve core support portion that supports an outer peripheral portion of the valve core in a ring shape and is connected to the battery case, a gas flow path forming portion is provided between the insulating member pressed by the gas to the valve core side and the valve core support portion at a position of an inner surface of the battery case that is closer to the inside of the battery case than the valve core, and the gas flow path forming portion forms a gas flow path that communicates with the valve core side.

[0013] (2) In the secondary battery described in (1), it is preferable that the gas flow path forming portion have a groove portion formed in the inner surface of the battery case of the valve core support portion.

[0014] (3) In the secondary battery described in (1), it is preferable that the gas flow path forming portion have a protrusion portion formed in the inner surface of the battery case of the valve core support portion.

[0015] (4) In the secondary battery described in any one of (1) to (3), it is preferable that the valve core support portion be a resin valve core support portion formed of a thermoplastic resin material.

[0016] (5) In the secondary battery described in any one of (1) to (4), it is preferable that the valve core be formed of a member having a tensile strength that is smaller than a tensile strength of the battery case, and the valve core support portion be connected to the battery case via a ring-shaped member of the same material as the battery case. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic cross-sectional view of a secondary battery that is one form of the present embodiment.

[0018] Figure 2 is a schematic cross-sectional view of a secondary battery that is one form of the present embodiment. Figure 1 is an enlarged cross-sectional view of A in FIG. 1, and is an explanatory view of one state when the valve core is open.

[0019] Figure 3 is an enlarged cross-sectional view of A in FIG. 1, and is an explanatory view of one state when the valve core is open. Figure 1An enlarged sectional view of A part shown, and is an explanatory view of another state when the valve core is open.

[0020] Figure 4 is Figure 1 An enlarged sectional view of A part shown, and is an explanatory view of another state when the valve core is open.

[0021] Figure 5 is viewed from the inside of the case Figure 1 A perspective view of a safety valve in a secondary battery and a ring-shaped member engaged with a valve core support portion of the safety valve shown.

[0022] Figure 6 is Figure 5 A B-B partial sectional view shown.

[0023] Figure 7 is viewed from the inside of the case Figure 1 A perspective view of a safety valve in a first modification of a secondary battery and a ring-shaped member engaged with a valve core support portion of the safety valve shown.

[0024] Figure 8 is viewed from the inside of the case Figure 1 A perspective view of a safety valve in a second modification of a secondary battery and a ring-shaped member engaged with a valve core support portion of the safety valve shown.

[0025] Figure 9 is Figure 1 An enlarged sectional view of A part in a third modification of a secondary battery shown, and is an explanatory view of a state when the valve core is open.

[0026] BRIEF DESCRIPTION OF REFERENCE NUMERALS

[0027] 1 battery case

[0028] 2 electrode body

[0029] 3 insulating member

[0030] 4, 4B, 4C, 4D safety valve

[0031] 5, 5A, 5B current collecting terminal

[0032] 10, 10B, 10C, 10D secondary battery

[0033] 41, 41D valve core

[0034] 42, 42B, 42C, 42D valve core support portion

[0035] 42N inside surface of case

[0036] 42J, 42DJ resin valve core support portion

[0037] 43, 43B, 43C, 43D gas flow path forming portion

[0038] 44, 44D gas flow path

[0039] 112 annular member

[0040] 411, 411D outer peripheral portion

[0041] 431, 431B, 431D recessed portion

[0042] 431C protruding portion

[0043] GS gas DETAILED DESCRIPTION

[0044] <Explanation of the secondary battery>

[0045] Next, a secondary battery of one mode of the above-described disclosed technology will be described in detail with reference to the drawings. Figure 1 A schematic cross-sectional view of the secondary battery of one mode of the present embodiment is shown. Figure 2 An enlarged cross-sectional view of the A portion shown, and a diagram showing one state when the valve element is open. Figure 1 An enlarged cross-sectional view of the A portion shown, and a diagram showing one state when the valve element is open. Figure 3 An enlarged cross-sectional view of the A portion shown, and a diagram showing another state when the valve element is open. Figure 1 An enlarged cross-sectional view of the A portion shown, and a diagram showing another state when the valve element is open. Figure 4 An enlarged cross-sectional view of the A portion shown, and a diagram showing another state when the valve element is open. Figure 1 An enlarged cross-sectional view of the A portion shown, and a diagram showing another state when the valve element is open. Figure 5 A perspective view of the safety valve in the secondary battery shown, and the annular member engaged with the valve element support portion of the safety valve, viewed from the inside of the case. Figure 1 A perspective view of the safety valve in the secondary battery shown, and the annular member engaged with the valve element support portion of the safety valve, viewed from the inside of the case. Figure 6 A perspective view of the safety valve in the secondary battery shown, and the annular member engaged with the valve element support portion of the safety valve, viewed from the inside of the case. Figure 5 A B-B partial cross-sectional view of the safety valve shown. Figure 6 A partial cross-sectional view of the valve element support portion, in which the intermediate portion between the inner peripheral side and the outer peripheral side is cut into a circular arc shape, and the cut surface is viewed horizontally from the inner peripheral side. Further, in the drawing, the valve element support portion is shown as a circular shape. Figures 1-4 In the drawings, etc., the X direction indicates the long side direction of the battery case, the Y direction indicates the short side direction (width direction) of the battery case, and the Z direction indicates the up-down direction of the battery case. In addition, the arrow U indicates the upper side of the battery case, and the arrow D indicates the lower side of the battery case.

[0046] As shown in FIG. 1, the secondary battery 1 includes a battery case 2, a safety valve 3, and a battery cell 4. Figures 1-6As shown, the secondary battery 10 is a sealed type secondary battery 10 provided with a battery case 1, an electrode body 2 housed in the battery case 1 in a sealed manner, an insulating member 3 interposed between the battery case 1 and the electrode body 2, and a safety valve 4 capable of discharging a gas GS whose pressure or temperature has risen to a prescribed value or more in the battery case 1 to the outside of the battery case 1, and provided to the battery case 1 at a position facing the insulating member 3.

[0047] Here, the battery case 1 is provided with a square tubular case main body 11 having rectangular shaped opening portions 114 (114A, 114B) at both end portions in the longitudinal direction (X direction), and plate-shaped cover bodies 12 (12A, 12B) that seal the respective opening portions 114 (114A, 114B) of the case main body 11. The battery case 1 can be formed of, for example, a stainless steel plate (for example, JIS standard: SUS304 or the like) that has excellent pressure resistance, but is not necessarily limited thereto. The case main body 11 and the cover bodies 12 are formed of metal members of the same material and are joined in a watertight manner by laser welding or the like. Further, the prescribed value of the gas pressure is, for example, a reference value determined in accordance with the amount of deformation of the battery case 1 or the like, and the prescribed value of the gas temperature is, for example, a reference value determined in accordance with the melting point of the insulating member 3 or the like. The battery case 1 is not necessarily limited to the above-described shape, and can be, for example, a battery case constituted by a bottomed square tubular case main body having one opening portion and a cover body that seals the opening portion.

[0048] The electrode body 2 in which the positive electrode body 21 and the negative electrode body 22 are stacked with the separator 23 interposed therebetween is housed in the battery case 1 in a sealed manner. Here, the electrode body 2 is formed by winding the strip-shaped positive electrode body 21 and the strip-shaped negative electrode body 22 with the strip-shaped separator 23 interposed therebetween in a direction orthogonal to the longitudinal direction (X direction) and pressing them in the short direction (Y direction) to be stacked in a flat shape. Therefore, the end portions of the positive electrode body 21, the negative electrode body 22, and the separator 23 are open at both end edge portions 2T in the longitudinal direction (X direction) of the electrode body 2. Therefore, in the case where the positive electrode body 21 and the negative electrode body 22 are short-circuited or the like, high-temperature gas GS or the like is mainly emitted from the end edge portions 2T in the longitudinal direction (X direction) of the electrode body 2.

[0049] In addition, in order to ensure electrical insulation between the battery case 1 and the electrode body 2, an insulating member 3 formed of an insulating film is interposed between the battery case 1 and the electrode body 2. The length of the insulating member 3 in the longitudinal direction (X direction) of the electrode body 2 is longer than the length of the electrode body 2 in the longitudinal direction, and is formed as a cylindrical body with both end edge portions 3T in the longitudinal direction (X direction) open. Also, the high-temperature gas GS and the like emitted from the end edge portion 2T in the longitudinal direction (X direction) of the electrode body 2 is divided into the battery case 1 side and the electrode body 2 side by the insulating member 3, and moves toward the safety valve 4 side. Here, both end edge portions 3T in the longitudinal direction of the insulating member 3 are entirely open, but need not necessarily be limited thereto, and can be open only in the vicinity of the current collecting terminal 5 and the injection port 122 described later. The insulating member 3 can be formed of, for example, a polypropylene (PP) resin or the like.

[0050] The current collecting terminal 5 electrically connected to the current collecting foil of the electrode body 2 is fixed to the lid body 12 in a watertight manner via an insulating resin portion 6. The insulating resin portion 6 can be formed of, for example, a polyphenylene sulfide (PPS) resin or the like. The current collecting terminal 5 (5A) for the positive electrode, which is engaged with the tab of the current collecting foil 211 of the positive electrode body 21, is inserted into the through hole 121A and fixed to the one lid body 12 (12A) via the insulating resin portion 6 (6A). Figure 1 In addition, the current collecting terminal 5 (5B) for the negative electrode, which is engaged with the tab of the current collecting foil 221 of the negative electrode body 22, is inserted into the through hole 121B and fixed to the other lid body 12 (12B) via the insulating resin portion 6 (6B). Furthermore, the injection port 122 for injecting the electrolyte 7 is formed in the one lid body 12 (12A), and is sealed by a plug 123 after the electrolyte 7 is injected. Figure 1

[0051] The through hole 111 for the safety valve 4 is formed in the upper end portion of the case main body 11. The safety valve 4 has a valve core 41 that can be opened, and a valve core support portion 42 that supports the outer peripheral portion 411 of the valve core 41 in a ring shape and is connected to the battery case 1 (112). The outer peripheral portion 411 of the valve core 41 is formed to have a larger thickness than the inner peripheral side. Also, the lower end portion 411K of the outer peripheral portion 411 is embedded in and fixed to the upper end portion of the valve core support portion 42, which is formed in a ring shape. In addition, a V-shaped groove 412 for cracking is formed in an X-shaped cross section at a position on the inner peripheral side of the outer peripheral portion 411 of the valve core 41. Figure 5 The shape of the V-shaped groove 412 is merely an example, and can be a shape other than that shown in the drawing. Figure 5 Here, the safety valve 4 is formed in a circular shape as a whole, but need not necessarily be limited thereto, and can be formed in an oblong shape or an elliptical shape, for example.

[0052] ​Further, the lower portion of the valve core support portion 42 is inserted into the penetration hole 111 of the battery case 1 (the case main body 11) and protrudes toward the position inside the case from the battery case 1. The annular member 112 of the battery case 1 is connected to the outer peripheral portion of the valve core support portion 42. The annular member 112 is formed of a metal plate (for example, a stainless steel plate) of the same material as the battery case 1. Further, the annular member 112 is joined to the case main body 11 by a welding portion 113 formed in a continuous manner on the outer peripheral side of the penetration hole 111 and becomes a part of the battery case 1. The welding portion 113 can be formed by laser welding, for example.

[0053] Further, on the case inner surface 42N of the valve core support portion 42 at the position inside the case from the valve core 41, a gas flow path forming portion 43 is provided between the insulating member 3 pressed to the valve core 41 side by the gas GS rising to a prescribed value or more in the battery case 1 in the gas pressure or the gas temperature and the valve core support portion 42, and the gas flow path forming portion 43 forms a gas flow path 44 communicating with the valve core 41 side. Therefore, if the gas pressure or the gas temperature rises to a prescribed value or more in the battery case 1, the gas GS flowing at the position of the battery case 1 side from the insulating member 3 is supplied to the valve core 41 side via the gas flow path 44 formed between the insulating member 3 pressed to the valve core 41 side by the electrode body 2 side gas GS and the valve core support portion 42. Further, the gas flow path forming portion 43 can be formed in a plurality of prescribed intervals from the outer peripheral side toward the inner peripheral side along the case inner surface 42N (the inner peripheral surface and the bottom surface) of the valve core support portion 42 formed in an annular shape. In this case, the gas flow path 44 is formed in a plurality of from the outer peripheral side of the valve core support portion 42 toward the valve core 41 side.

[0054] Further, with the gas GS supplied to the valve core 41 side from the gas flow path 44, the valve core 41 is opened, and it is possible to discharge the gas GS from the safety valve 4 after the valve core 41 is opened to the outside of the battery case 1. As a result, it is possible to provide the sealed type secondary battery 10 capable of ensuring the gas flow path 44 supplying the gas GS to the safety valve 4 covered by the insulating member 3 when the gas pressure or the gas temperature rises to a prescribed value or more in the battery case 1 and the safety valve 4 easily operates properly.

[0055] The gas flow path forming portion 43 can be formed in various shapes, but here, a groove portion 431 formed on the case inner surface 42N of the valve core support portion 42 is provided. The groove portion 431 is formed in a U-shaped cross section. Further, the groove portion 431 is formed from the outer peripheral side to the inner peripheral side of the case inner surface 42N of the valve core support portion 42 in the radial direction of the valve core support portion 42 and is formed in a continuous manner in a manner of being bent in an L shape in the vertical direction (Z direction) and the radial direction. The groove portions 431 are formed at equal intervals in the circumferential direction of the valve core support portion 42. Therefore, in the case where the insulating member 3 is pressed to the valve core 41 side by the gas GS in the battery case 1, as shown in FIG. 6, the gas flow path 44 is formed in a plurality of from the outer peripheral side of the valve core support portion 42 toward the valve core 41 side. Figure 2、 Figure 6 As shown, a portion of the insulating member 3 enters the groove portion 431 and forms a wavy crease in the insulating member 3 covering the safety valve 4.

[0056] In this case, a gap is easily generated between the insulating member 3 and the groove portion 431 and between the insulating member 3 and the housing inner surface 42N of the valve core support portion 42. Further, a gas flow path 44 through which the gas GS in the battery case 1 flows to the valve core 41 side via the gap is easily formed. As a result, as shown in FIG. 6, the V-shaped groove 412 of the valve core 41 is cracked by the gas GS supplied from the gas flow path 44 to the valve core 41 side, and the valve core 41 is opened. Further, the gas GS can be discharged from the safety valve 4 to the outside of the battery case 1 after the valve core 41 is opened. Figure 2

[0057] In addition, the valve core support portion 42 can be a resin valve core support portion 42J formed of a thermoplastic resin material. The valve core 41 is combined with the resin valve core support portion 42J by insert molding. The resin valve core support portion 42J can be formed of, for example, a polyphenylene sulfide (PPS) resin. In this case, before the gas pressure in the battery case 1 rises to a prescribed value or more, at the time when the gas temperature rises to a prescribed value or more, the combined portion of the resin valve core support portion 42J and the valve core 41 is softened or melted, and as shown in FIG. 7, the outer peripheral portion 411 of the valve core 41 can be separated from the resin valve core support portion 42J before the V-shaped groove 412 of the valve core 41 is cracked. Therefore, the rise in the gas pressure is slowed down, and the valve core 41 can be stably opened even if the amount of the gas GS supplied from the gas flow path 44 to the valve core 41 side is small. Figure 3

[0058] Further, as shown in FIG. 8, the resin valve core support portion 42J can also be formed by combining resin materials having different melting points. For example, the resin valve core support portion 42J can be a member in which a first resin material 42J1 that is combined with the valve core 41 and the annular member 112 and has a high melting point and a second resin material 42J2 that is sandwiched between the first resin material 42J1 and has a lower melting point than the first resin material 42J1 are laminated. For example, the first resin material 42J1 can be formed of a polyphenylene sulfide (PPS) resin having a melting point of about 290°C, and the second resin material 42J2 can be formed of a polypropylene (PP) resin having a melting point of about 170°C. Figure 4 In this case, at the time when the gas temperature rises to the melting point or the softening temperature of the second resin material 42J2, as shown in FIG. 9, the V-shaped groove 412 of the valve core 41 is cracked by the gas GS supplied from the gas flow path 44 to the valve core 41 side, and the valve core 41 is opened. Further, the gas GS can be discharged from the safety valve 4 to the outside of the battery case 1 after the valve core 41 is opened.

[0059] Figure 4 ​​​As shown, the outer peripheral portion 411 of the valve element 41 can be separated from the resin valve element support portion 42J. Therefore, even if the amount of the gas GS supplied from the gas flow path 44 to the valve element 41 side is small, the valve element 41 can be stably opened at a lower temperature than in the case where the resin valve element support portion 42J is as shown. Figure 3 As shown, the outer peripheral portion 411 of the valve element 41 can be separated from the resin valve element support portion 42J. Therefore, even if the amount of the gas GS supplied from the gas flow path 44 to the valve element 41 side is small, the valve element 41 can be stably opened at a lower temperature than in the case where the resin valve element support portion 42J is as shown.

[0060] In addition, in the present secondary battery 10, the valve element 41 can be formed of a member having a tensile strength smaller than that of the battery case 1, and the valve element support portion 42 can be connected to the battery case 1 via a ring-shaped member 112 of the same material as the battery case 1. The valve element 41 can be formed of, for example, an aluminum material after annealing (tensile strength: 70 to 100 N / mm 2 2), and the battery case 1 and the ring-shaped member 112 can be formed of, for example, an austenitic stainless steel (tensile strength: 590 N / mm 2 2).

[0061] In this case, the pressure resistance of the battery case 1 to the gas GS can be improved, and even if the amount of the gas GS supplied from the gas flow path 44 formed between the insulating member 3 and the valve element support portion 42 to the valve element 41 side is small when the gas pressure rises, the valve element 41 having a small tensile strength can be stably opened.

[0062] Further, in the lithium ion secondary battery as an example of the present secondary battery 10, the current collecting foil 211 of the positive electrode body 21 can use, for example, an aluminum foil, and the active material coated on the current collecting foil 211 of the positive electrode body 21 can use, for example, a lithium transition metal oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNiO2, etc.). In addition, the current collecting foil 221 of the negative electrode body 22 can use, for example, a copper foil, and the active material coated on the current collecting foil 221 of the negative electrode body 22 can use, for example, graphite, hard carbon, soft carbon, etc. In addition, the separator 23 can use, for example, a porous sheet of a polypropylene resin, a polyethylene resin, etc. Further, the electrolyte 7 can use a publicly known nonaqueous electrolyte. The current collecting terminal 5A of the positive electrode can be, for example, made of aluminum, and the current collecting terminal 5B of the negative electrode can be, for example, made of copper.

[0063] In addition, the present secondary battery 10 can be manufactured by the following steps. That is, the electrode body 2 surrounded by the insulating member 3 is housed in the case main body 11 of the battery case 1, the current collecting foils 211, 221 of the electrode body 2 are connected to the current collecting terminals 5 (5A, 5B) fixed to the lid body 12, and the opening portion 114 of the case main body 11 is sealed with the lid body 12, whereby assembly is performed, after which the electrolyte 7 is injected and primary charging, aging, etc. are performed to manufacture the battery.

[0064]

[0065] ​The embodiment described in detail above is merely an example and does not limit the technology of the present disclosure at all. Therefore, the technology of the present disclosure can be variously modified and altered without departing from the scope of the gist thereof. Figure 7 A perspective view of a safety valve and a ring-shaped member engaged with a valve core support portion of the safety valve in a first modified example of the secondary battery shown as viewed from the inside of the case. Figure 1 A perspective view of a safety valve and a ring-shaped member engaged with a valve core support portion of the safety valve in a first modified example of the secondary battery shown as viewed from the inside of the case. Figure 8 A perspective view of a safety valve and a ring-shaped member engaged with a valve core support portion of the safety valve in a first modified example of the secondary battery shown as viewed from the inside of the case. Figure 1 A perspective view of a safety valve and a ring-shaped member engaged with a valve core support portion of the safety valve in a first modified example of the secondary battery shown as viewed from the inside of the case. Figure 9 A perspective view of a safety valve and a ring-shaped member engaged with a valve core support portion of the safety valve in a first modified example of the secondary battery shown as viewed from the inside of the case. Figure 1 An enlarged sectional view of A portion in a third modified example of the secondary battery shown and a state explanatory view at the time of opening of the valve core.

[0066] In the present secondary battery 10, as shown in Figures 2-5 The gas flow path forming portion 43 formed in the case inner surface 42N of the valve core support portion 42 is a groove portion 431 formed continuously in an L shape bent in the up-and-down direction (Z direction) and the radial direction from the outer peripheral side to the inner peripheral side of the case inner surface 42N of the valve core support portion 42, but is not necessarily limited thereto.

[0067] For example, as in the secondary battery 10B of the first modified example shown in Figure 7 In this case, in the case where the insulating member 3 is pressed to the valve core 41 side by the gas GS in the battery case 1, a part of the insulating member 3 also enters the groove portion 431B, and a wavy crease is formed in the insulating member 3 covering the safety valve 4. Also, a gap is easily generated between the insulating member 3 and the groove portion 431B and between the insulating member 3 and the case inner surface 42N of the valve core support portion 42B, and a gas flow path 44 through which the gas GS in the battery case 1 flows to the valve core 41 side via the gap can be formed.

[0068] In addition, as in the secondary battery 10C of the second modified example shown in Figure 8As with the secondary battery 10C of the second modification example shown, the gas flow path forming portion 43C formed in the housing inner surface 42N of the valve core support portion 42C of the safety valve 4C can also be a protrusion 431C formed in the housing inner surface 42N of the valve core support portion 42C. The protrusion 431C protrudes downward in the upward and downward direction (Z direction). In this case, in the event that the insulating member 3 is pressed by the gas GS in the battery housing 1 to the valve core 41 side, a portion of the insulating member 3 will be pressed downward by the protrusion 431C, and a wavy crease will also be formed in the insulating member 3 covering the safety valve 4. Thus, a gap is easily created between the insulating member 3 and the protrusion 431C, and between the insulating member 3 and the housing inner surface 42N of the valve core support portion 42C, and a gas flow path 44 through which the gas GS in the battery housing 1 flows to the valve core 41 side via this gap can be formed. Furthermore, the protrusion 431C is formed in a semispherical shape in the present embodiment, but can be, for example, a square cylindrical shape or a triangular pyramid shape. In addition, the gas flow path forming portion 43C formed in the housing inner surface 42N of the valve core support portion 42C can also have both a groove portion 431 and a protrusion 431C. Figure 8

[0069] In addition, in the present secondary battery 10, the annular member 112 of the battery housing 1 is connected to the outer peripheral portion of the valve core support portion 42 of the safety valve 4, but need not necessarily be limited thereto. For example, as with the secondary battery 10D of the third modification example shown, Figure 9 As with the secondary battery 10D of the third modification example shown, the outer peripheral portion of the valve core support portion 42D of the safety valve 4D can also be directly connected to the battery housing 1 (the housing main body 11). Furthermore, the gas flow path forming portion 43D formed in the housing inner surface 42N of the valve core support portion 42D can also have a groove portion 431D formed in the housing inner surface 42N of the valve core support portion 42D. In this case, in the event that the insulating member 3 is pressed by the gas GS in the battery housing 1 to the valve core 41D side, a portion of the insulating member 3 will also enter the groove portion 431D, and a wavy crease will also be formed in the insulating member 3 covering the safety valve 4. Thus, a gap is easily created between the insulating member 3 and the groove portion 431D, and between the insulating member 3 and the housing inner surface 42N of the valve core support portion 42D, and a gas flow path 44D through which the gas GS in the battery housing 1 flows to the valve core 41D side via this gap can be formed. Furthermore, the valve core support portion 42D is a resin valve core support portion 42DJ formed of a thermoplastic resin material, and the outer peripheral portion 411D of the battery housing 1 (the housing main body 11) and the valve core 41D are combined with the resin valve core support portion 42DJ by insert molding.​

Claims

1. A secondary battery which is a sealed secondary battery, comprising: a battery case; an electrode body housed in the battery case in a sealed manner; an insulating member interposed between the battery case and the electrode body; and a safety valve capable of discharging a gas to an outside of the battery case when a gas pressure or a gas temperature in the battery case rises above a prescribed value, and provided to the battery case at a position facing the insulating member, wherein the safety valve comprises a valve core capable of opening and a valve core support portion supporting an outer peripheral portion of the valve core in a ring shape and connected to the battery case, a gas flow path forming portion is provided between the insulating member pressed by the gas to the valve core side and the valve core support portion at an inner case surface of the valve core support portion at a position inside the battery case than the valve core, and the gas flow path forming portion forms a gas flow path communicating with the valve core side.

2. The secondary battery according to claim 1, wherein the gas flow path forming portion comprises a groove portion formed in the inner case surface of the valve core support portion.

3. The secondary battery according to claim 1, wherein the gas flow path forming portion comprises a protrusion portion formed in the inner case surface of the valve core support portion.

4. The secondary battery according to any one of claims 1 to 3, wherein the valve core support portion is a resin valve core support portion formed of a thermoplastic resin material.

5. The secondary battery according to any one of claims 1 to 4, wherein the valve core is formed of a member having a tensile strength smaller than a tensile strength of the battery case, and the valve core support portion is connected to the battery case via a ring-shaped member of the same material as the battery case. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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