Valve structure for power storage device and power storage device

Abstract

To provide a valve structure for a power storage device and a power storage device that prevent moisture from entering a container in which a power storage device element is housed.SOLUTION: A valve structure for a power storage device includes a passage that communicates the inside and outside of a container that houses a power storage device element, and a check valve that is arranged so as to block the passage, and is opened when the internal pressure of the container rises due to gas generated inside the container, and passes the gas from the inside to the outside of the container, and the check valve includes a valve seat and a valve body that contacts the valve seat in the closed state, and the valve seat and the valve body come into contact with each other at a plurality of places in the closed state.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a valve structure for an electricity storage device and an electricity storage device including the same. [Background technology]

[0002] Patent Document 1 discloses a battery in which a battery element is housed in a pouch. A valve structure having a check valve is attached to the heat-sealed portion formed along the periphery of the pouch. This check valve is configured to operate and release gas when the internal pressure of the pouch rises above a certain level.

[0003] Patent Document 2 discloses a battery in which a battery element is housed in a box-shaped laminated container. This laminated container has a flange-shaped heat-sealed portion formed along its periphery, which has a portion (hereinafter referred to as an easy-peel portion) that is easier to peel than other portions. The easy-peel portion peels when the internal pressure of the laminated container rises above a certain level, and gas is released through a hole formed in the center of the easy-peel portion. Unlike the check valve in Patent Document 1, the easy-peel portion is a break valve that does not return to its original state once peeled. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-31934 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-153841 Summary of the Invention [Problem to be solved by the invention]

[0005] A check valve is generally a one-way valve designed to prevent backflow. However, in a battery such as that described in Patent Document 1, even a small amount of moisture from the atmosphere entering the pouch can cause battery degradation, so backflow prevention must be performed with greater precision. Therefore, it is practically difficult for a check valve that vents gas from the pouch described in Patent Document 1 to completely prevent the entry of air into the pouch to the high level required for a battery. Therefore, a battery such as that described in Patent Document 1 faces the problem of moisture from the atmosphere entering the pouch, causing battery degradation.

[0006] On the other hand, in a battery such as that in Patent Document 2, once the rupture valve is ruptured, air enters the laminated container through the passage formed by the rupture. Therefore, even when a rupture valve is used as in Patent Document 2, there is a problem in that moisture contained in the air enters the laminated container, causing deterioration of the battery.

[0007] An object of the present invention is to provide a valve structure that can prevent moisture from entering a container that houses an electricity storage device element, and an electricity storage device including the valve structure. [Means for solving the problem]

[0008] A valve structure for an electricity storage device according to a first aspect of the present invention comprises a passage that connects the inside and outside of a container that houses an electricity storage device element, and a check valve that is arranged to block the passage and opens when the internal pressure of the container increases due to gas generated inside the container, allowing the gas to pass from the inside to the outside of the container, and the check valve includes a valve seat and a valve body that contacts the valve seat in a closed state, and the valve seat and the valve body contact each other at multiple points in the closed state.

[0009] A valve structure for an electricity storage device according to a second aspect of the present invention is the valve structure for an electricity storage device according to the first aspect, wherein at least one of the valve seat and the valve body includes a multi-stage structure having a plurality of steps, and the valve seat and the valve body contact each other via the multi-stage structure in the closed state.

[0010] A valve structure for an electricity storage device according to a third aspect of the present invention is the valve structure for an electricity storage device according to the first or second aspect, wherein the valve seat includes an insertion hole into which the valve body is inserted in the closed state, the valve body includes an insertion portion that is inserted into the insertion hole in the closed state, the insertion hole having a shape that tapers toward the interior of the container, and the insertion portion having a shape that tapers toward the interior of the container to follow the shape of the insertion hole.

[0011] A valve structure for an electricity storage device according to a fourth aspect of the present invention is a valve structure for an electricity storage device according to any one of the first to third aspects, further comprising a valve body that houses the check valve, and the valve body includes a side wall that guides movement of the valve body when the check valve transitions from one of the closed state and the open state to the other.

[0012] A valve structure for an electricity storage device according to a fifth aspect of the present invention is the valve structure for an electricity storage device according to the fourth aspect, wherein the side wall includes a discharge hole formed so that the gas can be discharged when the check valve is in the open state.

[0013] A valve structure for an electricity storage device according to a sixth aspect of the present invention is the valve structure for an electricity storage device according to any one of the first to fifth aspects, and includes a liquid arranged so as to be in contact with the valve seat and the valve body.

[0014] A valve structure for an electricity storage device according to a seventh aspect of the present invention is the valve structure for an electricity storage device according to the sixth aspect, wherein the melting point of the liquid is 10° C. or lower.

[0015] An eighth aspect of the present invention provides a valve structure for an electricity storage device according to the sixth or seventh aspect, wherein the boiling point of the liquid is 150°C or higher.

[0016] A valve structure for an electricity storage device according to a ninth aspect of the present invention is the valve structure for an electricity storage device according to any one of the sixth to eighth aspects, wherein the liquid includes liquid paraffin.

[0017] A valve structure for an electricity storage device according to a tenth aspect of the present invention is the valve structure for an electricity storage device according to any one of the sixth to ninth aspects, wherein the viscosity of the liquid is in the range of 0.1 mPa·s to 2000 mPa·s.

[0018] An electricity storage device according to an eleventh aspect of the present invention comprises the valve structure for an electricity storage device according to any one of the first to tenth aspects, and the container to which the valve structure for an electricity storage device is attached. [Effects of the Invention]

[0019] The valve structure for an electricity storage device and the electricity storage device according to the present invention can prevent moisture from entering the container that houses the electricity storage device elements. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a plan view of an electricity storage device including a valve structure for an electricity storage device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line D2-D2 in FIG. [Figure 3] FIG. 2 is a front view of the valve structure of FIG. 1. [Figure 4] FIG. 4 is a bottom view of the valve structure of FIG. 3 . [Figure 5] FIG. 4 is a plan view of the valve structure of FIG. 3 . [Figure 6] FIG. 4 is a perspective view of the valve structure of FIG. 3 as viewed from the rear side. [Figure 7] 7 is a cross-sectional view taken along line D7-D7 in FIG. 4. [Figure 8] FIG. 8 is a perspective view of the valve body of FIG. 7 as viewed from the bottom side. [Figure 9] FIG. 9 is a front view of the valve body of FIG. 8. [Figure 10] FIG. 6 is a cross-sectional view of a valve structure for an electricity storage device according to a second embodiment. [Figure 11] FIG. 11 is a perspective view of the valve seat of FIG. 10 as viewed from above. [Figure 12] 10 is a cross-sectional view of a valve seat and a valve body included in a modified example of a valve structure for an electricity storage device. FIG. [Figure 13] FIG. 10 is a cross-sectional view of a valve seat and a valve body provided in a valve structure for an electricity storage device according to another modified example. [Figure 14] FIG. 10 is a plan view of an electricity storage device according to a modified example. [Figure 15] FIG. 10 is a plan view of an electricity storage device according to another modified example. [Figure 16] FIG. 10 is a plan view of an electricity storage device according to yet another modified example. [Figure 17] FIG. 10 is a plan view of an electricity storage device according to yet another modified example. [Figure 18] FIG. 10 is a cross-sectional view of a modified valve structure. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A valve structure for an electricity storage device according to one embodiment of the present invention, an electricity storage device including the same, and a method for manufacturing the same will be described below with reference to the drawings.

[0022] [1. First embodiment] <1-1. Overall configuration of the electricity storage device> FIG. 1 shows a plan view of an electricity storage device 100 including a valve structure 10 for an electricity storage device according to this embodiment. FIG. 2 is a cross-sectional view taken along line D2-D2 in FIG. 1. In these figures, for reference, parts that are not normally visible from the outside are partially shown with dotted lines. Hereinafter, for convenience of explanation, unless otherwise specified, the up-down direction in FIG. 1 will be referred to as "front-back", the left-right direction will be referred to as "left-right", and the up-down direction in FIG. 2 will be referred to as "up-down". However, the orientation of the electricity storage device 100 during use is not limited to these.

[0023] The electricity storage device 100 includes a housing 110, an electricity storage device element 120, a tab 130, and a tab film 140. The housing 110 includes an internal space S1 and a peripheral seal portion 150. The electricity storage device element 120 is housed in the internal space S1 of the housing 110. One end of the tab 130 is joined to the electricity storage device element 120, and the other end protrudes outward from the peripheral seal portion 150 of the housing 110, with a portion of the space between the one end and the other end being fused to the peripheral seal portion 150 via the tab film 140.

[0024] The housing 110 includes a container 110A. The container 110A is configured to include packaging materials 111 and 112. In a plan view, the packaging materials 111 and 112 are heat-sealed and fused together around the outer periphery of the container 110A, thereby forming a peripheral seal portion 150. The peripheral seal portion 150 forms an internal space S1 of the container 110A that is isolated from the external space. The peripheral seal portion 150 defines the periphery of the internal space S1 of the container 110A. Note that the heat sealing method used here may be heat fusion from a heat source, ultrasonic fusion, or the like. In any case, the peripheral seal portion 150 refers to the portion where the packaging materials 111 and 112 are fused and integrated. As shown in FIG. 2, the portion of the peripheral seal portion 150 that sandwiches the tab 130 and the tab film 140 is made up of a unified package of the packaging material 112, the tab 130, the pair of tab films 140, and the packaging material 111, and the portion of the peripheral seal portion 150 that sandwiches only the pair of tab films 140 is made up of a unified package of the packaging material 112, the pair of tab films 140, and the packaging material 111.

[0025] The packaging materials 111 and 112 are composed of, for example, a resin molded product or a film. The resin molded product referred to here can be manufactured by methods such as injection molding, pressure forming, vacuum forming, and blow molding, and in-mold molding may also be used to impart design and functionality. The resin may be polyolefin, polyester, nylon, ABS, or the like. The film referred to here refers to, for example, a resin film that can be manufactured by methods such as an inflation method or a T-die method, or a resin film laminated on a metal foil. The film referred to here may be stretched or not, and may be a single-layer film or a multilayer film. The multilayer film referred to here may be manufactured by a coating method, or may be a film in which multiple films are bonded together with an adhesive or the like, or may be manufactured by a multilayer extrusion method.

[0026] As described above, the packaging materials 111 and 112 can be configured in various ways, but in this embodiment, they are configured from laminate films. The laminate films can be laminates formed by laminating a base layer, a barrier layer, and a heat-sealable resin layer. The base layer functions as the base material of the packaging materials 111 and 112 and is typically an insulating resin layer that forms the outer layer of the container 110A. The barrier layer not only improves the strength of the packaging materials 111 and 112 but also functions to prevent at least moisture and the like from penetrating into the power storage device 100 and is typically a metal layer made of aluminum alloy foil or the like. The heat-sealable resin layer is typically made of a heat-sealable resin such as polyolefin and forms the innermost layer of the container 110A.

[0027] The shape of container 110A is not particularly limited and may be, for example, a bag (pouch). Examples of bag-like shapes include three-sided sealed, four-sided sealed, pillow-shaped, and gusseted. However, container 110A of this embodiment has a shape as shown in FIG. 2 and is manufactured by heat-sealing packaging material 111, which is formed into a tray shape, and packaging material 112, which is also formed into a tray shape and overlaid on packaging material 111, along their outer peripheries in a plan view. Packaging material 111 includes a rectangular annular flange portion 111A corresponding to the outer periphery in a plan view, and a molded portion 111B that is continuous with the inner edge of flange portion 111A and bulges downward therefrom. Similarly, packaging material 112 includes a rectangular annular flange portion 112A corresponding to the outer periphery in a plan view, and a molded portion 112B that is continuous with the inner edge of flange portion 112A and bulges upward therefrom. Packaging materials 111 and 112 are overlapped so that their respective molded portions 111B and 112B bulge in opposite directions. In this state, flange portion 111A of packaging material 111 and flange portion 112A of packaging material 112 are heat-sealed to form a periphery seal portion 150. Peripheral seal portion 150 extends around the entire outer periphery of container 110A and is formed in a rectangular ring shape. One of packaging materials 111 and 112 may be in sheet form.

[0028] The electricity storage device element 120 includes at least a positive electrode, a negative electrode, and an electrolyte, and is, for example, an electricity storage member such as a lithium-ion battery (secondary battery) or a capacitor. When an abnormality occurs in the electricity storage device element 120, gas may be generated in the internal space S1 of the container 110A. When the electricity storage device 100 is a lithium-ion battery, gases such as volatile organic solvents, carbon monoxide, carbon dioxide, methane, ethane, hydrogen, and hydrogen fluoride may be generated in the internal space S1 of the container 110A due to volatilization of the organic solvent serving as the electrolyte and decomposition of the electrolytic solution. When the electricity storage device 100 is a capacitor, gas may be generated in the internal space S1 of the container 110A due to a chemical reaction in the capacitor. The electricity storage device 100 may also be an all-solid-state battery. In this case, the electricity storage device element 120 may include a solid electrolyte capable of generating gas. For example, when the solid electrolyte is sulfide-based, hydrogen sulfide gas may be generated.

[0029] The tabs 130 are metal terminals used for inputting and outputting power to and from the power storage device element 120. The tabs 130 are arranged separately at the left and right ends of the peripheral seal portion 150 of the container 110A, one forming a positive electrode terminal and the other forming a negative electrode terminal. One left and right end of each tab 130 is electrically connected to an electrode (positive electrode or negative electrode) of the power storage device element 120 in the internal space S1 of the container 110A, and the other end protrudes outward from the peripheral seal portion 150. The above-described configuration of the power storage device 100 is particularly preferable for use in, for example, electric vehicles, hybrid vehicles, and other electric vehicles in which a large number of power storage devices 100 are connected in series and used at high voltage. The attachment positions of the two tabs 130 forming the positive and negative electrode terminals are not particularly limited, and they may be arranged, for example, on the same side of the peripheral seal portion 150.

[0030] The metal material constituting the tab 130 is, for example, aluminum, nickel, copper, etc. When the power storage device element 120 is a lithium ion battery, the tab 130 connected to the positive electrode is typically made of aluminum, etc., and the tab 130 connected to the negative electrode is typically made of copper, nickel, etc.

[0031] The left tab 130 is sandwiched between the packaging materials 111 and 112 at the left end of the peripheral seal portion 150 with the tab film 140 interposed therebetween. The right tab 130 is also sandwiched between the packaging materials 111 and 112 at the right end of the peripheral seal portion 150 with the tab film 140 interposed therebetween.

[0032] The tab film 140 is a so-called adhesive film, and is configured to adhere to both the packaging materials 111, 112 and the tab 130 (metal). By using the tab film 140, the tab 130 and the innermost layer (thermally adhesive resin layer) of the packaging materials 111, 112 can be fixed together even if they are made of different materials. The tab film 140 is integrated with the tab 130 by being fused and fixed to it in advance, and the tab 130 with the tab film 140 fixed thereto is sandwiched between the packaging materials 111, 112 and fused to be integrated as shown in FIG. 2.

[0033] When gas is generated in the internal space S1 of the container 110A as the power storage device 100 operates, the pressure in the internal space S1 gradually increases. If the pressure in the internal space S1 increases excessively, the container 110A may burst, damaging the power storage device 100. The housing 110 is provided with a valve structure 10 as a mechanism for preventing such an event. The valve structure 10 is a gas vent valve for adjusting the pressure in the internal space S1, and is attached to, for example, the peripheral seal portion 150 of the container 110A. The configuration of the valve structure 10 will be described in detail below.

[0034] <1-2. Valve structure configuration> FIG. 3 is a front view of the valve structure 10. The valve structure 10 includes a valve main body 20. The valve main body 20 includes a first body 30, a second body 40, and a check valve 50 (see FIG. 7). In this embodiment, the first body 30 and the second body 40 are arranged consecutively in this order in a direction from the inside to the outside of the container 110A (see FIG. 1) (from the rear to the front). FIG. 4 is a view of the valve structure 10 as viewed from the first body 30 side (from the rear side). FIG. 5 is a view of the valve structure 10 as viewed from the second body 40 side (from the front side). FIG. 6 is a perspective view of the valve structure 10 as viewed from the first body 30 side (from the rear side).

[0035] FIG. 7 is a cross-sectional view taken along line D7-D7 in FIG. 4. As shown in FIG. 7, the check valve 50 is accommodated in the accommodation space S2 defined by the first body 30 and the second body 40. The check valve 50 opens when the internal pressure of the container 110A (see FIG. 1) increases due to gas generated inside the container 110A, allowing the gas to pass from the interior to the exterior of the container 110A. More specifically, the check valve 50 serves as a relief valve that switches between an open state and a closed state depending on the pressure on its primary side, i.e., the pressure in the internal space S1 (see FIG. 1). A passage LA is formed inside the valve body 20. The passage LA connects the inside and outside of the container 110A and has an inlet 20A facing the internal space S1 of the container 110A and an outlet 20B facing the external space.

[0036] The check valve 50 is disposed so as to close the passage LA in the closed state. When the pressure in the internal space S1 increases due to gas generated in the internal space S1, the check valve 50 opens and allows the gas to pass from its primary side to its secondary side, i.e., from the internal space S1 to the external space. In the closed state, the check valve 50 seals the internal space S1 from the external space.

[0037] The first body 30 includes an attachment portion 31 and a connecting portion 32. The attachment portion 31 is a portion for attaching the valve structure 10 to the container 110A. When the container 110A is molded, the attachment portion 31 is heat-sealed together with the packaging materials 111, 112 via a heat-sealing film 11 (see FIG. 1). This heat-sealing fuses and joins the outer peripheral surfaces of the attachment portion 31 to the packaging materials 111, 112 via the heat-sealing film 11, and the attachment portion 31 is fixed to the peripheral seal portion 150 in a manner such that it is sandwiched between the packaging materials 111, 112 (see FIG. 2).

[0038] The connecting portion 32 is disposed outside the peripheral seal portion 150 and is not sandwiched between the packaging materials 111, 112 (see FIGS. 1 and 2). In addition, the second body 40, which is disposed further outside than the connecting portion 32, is also disposed outside the peripheral seal portion 150 and is not sandwiched between the packaging materials 111, 112. As a result, the risk of the check valve 50 held by the second body 40 being damaged by deformation or the like due to the heat generated when the mounting portion 31 is attached to the container 110A by heat sealing is reduced.

[0039] The attachment portion 31, the connecting portion 32, and the second body 40 extend coaxially. The attachment portion 31, the connecting portion 32, and the second body 40 share a common central axis C1. The attachment portion 31 has a first air passage LX, the second body 40 has a second air passage LY, and the connecting portion 32 has a third air passage LZ. These air passages LX to LZ also extend coaxially around the central axis C1. In this embodiment, the inlet 20A and the outlet 20B are disposed on the end surfaces in the front-rear direction rather than on the outer peripheral surface of the valve body 20. In particular, the central axis C1, which extends linearly in the front-rear direction, passes through the centers of the inlet 20A and the outlet 20B. Although not limited thereto, a cross section of the air passages LX to LZ perpendicular to the central axis C1 is circular. The air passages LX to LZ are connected to each other and collectively form a passage LA. The third ventilation passage LZ is disposed closer to the exterior of the container 110A than the first ventilation passage LX. The second ventilation passage LY is disposed further outside the container 110A than the third ventilation passage LZ.

[0040] 4 and 6, the mounting portion 31 has a non-circular outer shape when viewed along the direction in which the central axis C1 extends. More specifically, when viewed along the direction in which the central axis C1 extends, the mounting portion 31 has a first wing-shaped portion 31A that is formed to become thinner from the center in the left-right direction toward the left, and a second wing-shaped portion 31B that is formed to become thinner toward the right, when viewed along the direction in which the central axis C1 extends. Therefore, in this embodiment, the mounting portion 31 becomes thicker as it approaches the center in the width direction (left-right direction) of the electricity storage device 100, and becomes thinner as it approaches the ends in the width direction (left-right direction) of the electricity storage device 100.

[0041] In this embodiment, because the first wing-shaped portion 31A and the second wing-shaped portion 31B are formed, the outer peripheral surface of the mounting portion 31 forms a smoothly curved surface in both the lower half covered by the packaging material 111 and the upper half covered by the packaging material 112. Furthermore, compared to a case where the mounting portion 31 is formed cylindrically, the first wing-shaped portion 31A and the second wing-shaped portion 31B smooth the change in thickness of the power storage device 100 in the vertical direction at the transition position from the portion of the peripheral seal portion 150 where the mounting portion 31 is not sandwiched to the portion of the peripheral seal portion 150 where the mounting portion 31 is sandwiched. As a result, excessive force is not applied to the packaging materials 111 and 112 in the peripheral seal portion 150 around the position where the mounting portion 31 is attached. Therefore, the mounting portion 31 can be firmly fixed to the peripheral seal portion 150 via the heat-sealing film 11.

[0042] The outer shape of the connecting portion 32 is generally similar to a cylinder with a central axis C1 as its central axis, with a portion cut out. More specifically, the outer shape of the connecting portion 32 is generally similar to a cylinder with a central axis C1 as its central axis, with a plane cut out at a certain distance from the central axis C1 and a further plane cut out at a position symmetrical to the plane cut out with respect to the central axis C1. Thus, the connecting portion 32 has a pair of planes, a first plane 32A and a second plane 32B. The first plane 32A and the second plane 32B are parallel to each other (including when they are approximately parallel; the same applies hereinafter). The first plane 32A and the second plane 32B are parallel to the direction in which the central axis C1 extends (including when they are approximately parallel; the same applies hereinafter). In this embodiment, the first plane 32A and the second plane 32B are parallel to the direction in which the peripheral seal portion 150 extends (including when they are approximately parallel; the same applies hereinafter). The outer circumferential surface of the connecting portion 32 is composed of a first flat surface 32A, a second flat surface 32B, and curved surfaces 32C and 32D that connect the first flat surface 32A and the second flat surface 32B. When viewed along the direction in which the central axis C1 extends, the curved surfaces 32C and 32D each have an arc shape centered on the central axis C1 and overlap the outer shape of the second body 40. The connecting portion 32 as described above can be formed by cutting the outer circumferential surface of a cylindrical member so as to form the first flat surface 32A and the second flat surface 32B.

[0043] The second body 40 is cylindrical and, together with the first body 30, defines an accommodation space S2 that accommodates the check valve 50. The first body 30 and the second body 40 are assembled together with the check valve 50 accommodated in the accommodation space S2.

[0044] The first body 30 and the second body 40 are joined together by at least one of adhesive, threaded joints, and engagement of recesses and protrusions. In this embodiment, the first body 30 and the second body 40 are joined together by the engagement of the male threads 32X (see FIG. 7) formed on the outer surface of the connecting portion 32 of the first body 30 with the female threads 40A (see FIG. 7) formed on the inner surface of the second body 40, and by an adhesive applied to the male threads 32X and the female threads 40A. The adhesive may be made of any material, including, but not limited to, acid-modified polyolefin and epoxy resin. This type of adhesive is superior to, for example, an adhesive made of modified silicone resin in that it can suppress deterioration of adhesive performance due to the electrolyte solution contained in the container 110A. Any means may be used to join the first body 30 and the second body 40. Therefore, in this embodiment, at least one of the structure for engaging the male threads 32X and the female threads 40A and the adhesive may be omitted.

[0045] As described above, in this embodiment, the outer shapes of the mounting portion 31, the connecting portion 32, and the second body 40 all have different shapes when viewed along the direction in which the central axis C1 extends, depending on the role assigned to each part.

[0046] The second body 40 holds a portion of the valve structure 10 having a main structure for functioning as a gas vent valve. In this embodiment, the check valve 50 has a spring 60, a valve seat 70, and a valve element 80 as a valve mechanism housed in the second air passage LY inside the second body 40. The spring 60, the valve element 80, and the valve seat 70 are arranged in this order in the second air passage LY from the outlet 20B toward the inlet 20A. In this embodiment, as shown in FIGS. 7 and 8, the first body 30 and the valve seat 70 are configured as separate parts, but they may also be configured as an integrated unit.

[0047] The valve seat 70 receives the valve element 80 that is biased from the outside by the spring 60, and at this time, the valve structure 10 is in a closed state. The spring 60 is, for example, a coil spring, but is not limited to this and can also be, for example, a leaf spring.

[0048] In this embodiment, the valve seat 70 has a shape similar to a cylinder extending about a central axis C1. The valve seat 70 has an insertion hole 71 into which a portion of the valve element 80 is inserted when the check valve 50 is in a closed state. In this embodiment, the inner surface 71A of the insertion hole 71 is generally smooth. The diameter of the insertion hole 71 decreases toward the inlet 20A. In other words, the insertion hole 71 has a shape that tapers toward the inlet 20A.

[0049] The valve element 80 has a cylindrical base 81, a conical insertion portion 82 extending from a lower surface 81A of the base 81 toward the valve seat 70, and a cylindrical shaft portion 83 extending from an upper surface 81B of the base 81 toward the outlet 20B. The base 81, the insertion portion 82, and the shaft portion 83 extend about a central axis C1. When the check valve 50 is in a closed state, the insertion portion 82 is inserted into the insertion hole 71 of the valve seat 70. The outer shape of the insertion portion 82 is configured to match the inner shape of the insertion hole 71. Specifically, the diameter of the insertion portion 82 decreases from the base 81 toward the valve seat 70. That is, the insertion portion 82 tapers from the base 81 toward the valve seat 70. Therefore, when the check valve 50 transitions from an open state to a closed state, the insertion hole 71 guides the valve element 80 to a predetermined position. Therefore, when the check valve 50 is in a closed state, the position of the valve element 80 is unlikely to shift relative to the valve seat 70. In other words, the position of the valve element 80 is unlikely to shift relative to the central axis C1. The spring 60 extends spirally around the central axis C1. The shaft portion 83 of the valve element 80 is inserted into the space inside the spring 60. Therefore, the valve element 80 and the spring 60 are connected to each other.

[0050] In this embodiment, the valve seat 70 and the valve element 80 are configured to come into contact with each other at multiple locations so that they come into firmer contact with each other when the check valve 50 is in the closed state. More specifically, in this embodiment, at least one of the valve seat 70 and the valve element 80 includes a multi-stage structure 90 having multiple steps, and the valve seat 70 and the valve element 80 come into contact with each other via the multi-stage structure 90 when the check valve 50 is in the closed state. In this embodiment, the multi-stage structure 90 is formed in the valve element 80.

[0051] As shown in FIGS. 8 and 9 , the insertion portion 82 of the valve body 80 has a multi-stage structure 90 including a plurality of convex portions 91 and a plurality of concave portions 92. Such a multi-stage structure 90 can be realized, for example, by forming concave portions 92 in the insertion portion 82. The convex portions 91 and the concave portions 92 are alternately arranged in the direction in which the central axis C1 extends. The convex portions 91 and the concave portions 92 are formed over the entire circumferential direction of the insertion portion 82. The number of convex portions 91 in the multi-stage structure 90 can be selected arbitrarily as long as it is two or more. In this embodiment, the multi-stage structure 90 has six convex portions 91. The number of concave portions 92 in the multi-stage structure 90 is determined, for example, based on the number of convex portions 91. In this embodiment, the multi-stage structure 90 has six concave portions 92.

[0052] When the check valve 50 is in the closed state, the insertion portion 82 is inserted into the insertion hole 71, and the protrusions 91 of the multi-stage structure 90 formed on the insertion portion 82 contact the inner surface 71A of the insertion hole 71. In this embodiment, the multi-stage structure 90 has six protrusions 91, so when the check valve 50 is in the closed state, the valve seat 70 and the valve element 80 contact each other at six locations. Therefore, when the biasing force of the spring 60 is the same, the valve seat 70 and the valve element 80 contact each other with stronger pressure in this embodiment than when the valve seat 70 and the valve element 80 are in surface contact at one location. Therefore, when the check valve 50 is in the closed state, if the atmosphere and the moisture contained therein enter the valve structure 10 through the outlet 20B, the check valve 50 prevents the moisture from entering the container 110A beyond the check valve 50. This prevents the atmosphere and the moisture contained therein from entering the container 110A.

[0053] The side wall 42 of the second body 40 extends along the central axis C1 so as to guide the movement of the valve element 80 when the check valve 50 transitions from one of the closed state and the open state to the other. There is substantially no gap between the inner surface 42A of the side wall 42 and the surface of the base 81 of the valve element 80. In other words, the inner surface 42A of the side wall 42 and the surface of the base 81 of the valve element 80 are in contact with each other. Therefore, when the check valve 50 transitions from one of the closed state and the open state to the other, the base 81 of the valve element 80 moves along the central axis C1 while contacting the inner surface 42A of the side wall 42.

[0054] Because the inner surface 42A of the side wall 42 and the surface of the base 81 of the valve element 80 are in contact with each other, when the check valve 50 is in an open state, it is difficult for much gas to pass between the side wall 42 and the valve element 80. For this reason, in this embodiment, in addition to the outlet 20B, a discharge hole 42B is formed in the side wall 42 so that gas can be smoothly discharged when the check valve 50 is in an open state. The discharge hole 42B is a hole that penetrates the side wall 42. When gas is generated in the internal space S1 and the check valve 50 is in an open state, much of the gas is discharged to the outside through the gap between the valve seat 70 and the side wall 42 and the discharge hole 42B. Note that some of the gas is also discharged to the outside through the outlet 20B. The position at which the discharge hole 42B is formed in the side wall 42 can be selected arbitrarily. In this embodiment, the discharge hole 42B is formed in the side wall 42 at a position facing the valve seat 70. The discharge hole 42B may be formed in the side wall 42 at a position facing the valve body 80.

[0055] The valve seat 70 and the first body 30 can be bonded together, for example, with an adhesive. The material of the adhesive is not particularly limited, but a preferred example when the valve seat 70 is made of fluororubber and the first body 30 is made of a metal such as aluminum is the same adhesive as exemplified for joining the first body 30 and the second body 40. Furthermore, from the standpoint of preventing the valve structure 10 from being opened, adhesive can be applied to various other locations as appropriate. For example, adhesive can be applied between the rear end surface 41 of the second body 40 and the front end surface 32E of the connecting portion 32.

[0056] The mounting portion 31 is fixed to the peripheral seal portion 150 so that gas generated in the internal space S1 of the container 110A flows into the first air passage LX. That is, the first air passage LX inside the mounting portion 31 is connected to the internal space S1 of the container 110A. Therefore, when the pressure in the internal space S1, i.e., the pressure in the space on the primary side of the check valve 50, reaches a predetermined pressure, the gas flows out of the internal space S1 and passes through the first air passage LX and the third air passage LZ, pressing the valve element 80 toward the outlet 20B. When the valve element 80 is pressed and moves away from the valve seat 70, the spring 60 deforms, and the valve element 80 moves toward the outlet 20B, thereby opening the check valve 50. In this open state, gas generated in the internal space S1 flows through a gap formed between the valve element 80 and the valve seat 70 toward the outlet 20B and the discharge hole 42B and is discharged to the outside space. When the gas in the internal space S1 is discharged through the passage LA in this way, the pressure in the internal space S1 pressing the valve element 80 toward the outlet 20B weakens, and the force of the spring 60 urging the valve element 80 toward the inlet 20A increases. As a result, the shape of the spring 60 is restored, and the check valve 50 is again in the closed state.

[0057] In a closed state, the check valve 50 can prevent atmospheric air from entering the internal space S1 of the container 110A from the external space. Once the check valve 50 opens, the internal space S1 is maintained at a relatively high pressure equal to or higher than atmospheric pressure, making it particularly difficult for atmospheric air to enter the internal space S1. The valve structure 10, using the check valve 50 described above, can effectively prevent atmospheric air from entering the internal space S1 and prevent deterioration of the electricity storage device element 120 due to moisture and the like contained therein. Furthermore, even when the check valve 50 is open, atmospheric air is unlikely to enter the internal space S1. This is because, in the open state, the pressure on the primary side of the check valve 50 is maintained higher than or equal to the pressure on the secondary side thereof.

[0058] The materials constituting each part of the valve structure 10 are not particularly limited. As a preferred example, the valve body 80 can be made of a fluororesin such as polytetrafluoroethylene (PTFE), and the valve seat 70 can be made of a fluororubber such as polyvinylidene fluoride (FKM). Furthermore, the spring 60 can be made of a metal such as stainless steel, and the mounting portion 31, the second body 40, and the connecting portion 32 can be made of a metal such as aluminum alloy, stainless steel, steel plate, or titanium. The valve body 80 can also be made of a metal such as aluminum or stainless steel, or a fluororubber such as PTFE or FKM. When the valve body 80 is made of a fluororubber such as FKM, the valve seat 70 is preferably made of a fluororesin such as PTFE.

[0059] The heat-sealing film 11 shown in FIG. 1 and other figures is configured to be bonded by heat sealing to both the valve structure 10 and the packaging materials 111, 112 of the container 110A. The heat-sealing film 11 is fused to the attachment portion 31 of the first body 30 before the first body 30 and the second body 40 are assembled while the check valve 50 is accommodated in the accommodation space S2 (see FIG. 7). The heat-sealing film 11 is fused to the attachment portion 31 so as to cover most of the surface of the attachment portion 31. Various known adhesive films can be used as the heat-sealing film 11. The heat-sealing film 11 may be, for example, a single-layer film of maleic anhydride-modified polypropylene (PPa), or a multi-layer laminate film of PPa, polyethylene naphthalate (PEN), and PPa. Alternatively, a multi-layer laminate film of PPa, polypropylene (PP), and PPa may be used. Instead of the PPa resin, resins capable of bonding to metal, such as ionomer resin, modified polyethylene, and EVA, can also be used. In this embodiment, the heat-sealable film 11 employs a three-layer laminate film including a core material, consisting of PPa / polyester fiber / PPA. Various known materials can be used as the core material, in addition to the polyester fiber described above. For example, the core material may be a polyester film such as PEN, polyethylene terephthalate, or polybutylene terephthalate, or it may be polyamide fiber or carbon fiber.

[0060] Furthermore, from the viewpoint of electrolyte resistance in particular, it is preferable to coat the surface of the mounting portion 31 with a corrosion inhibitor to form a corrosion-preventing film layer. This applies particularly when the mounting portion 31 is made of a metal such as aluminum, but it can also apply when the mounting portion 31 is made of other materials. Such a coating can be applied by immersing the mounting portion 31 in a corrosion-preventing liquid and then performing a baking process. This allows a corrosion-preventing film layer to be formed on the outer surface of the mounting portion 31 and on the inner surface facing the first air passage LX, thereby preventing corrosion of the outer surface due to gas generated from the power storage device element 120 and corrosion of the inner surface due to gas passing through the first air passage LX. Furthermore, from the viewpoint of electrolyte resistance in particular, a similar coating may be applied to the surfaces of the connecting portion 32, the second body 40, and the check valve 50 as well as the mounting portion 31 to form a corrosion-preventing film layer. When applying a corrosion inhibitor coating to the surfaces of the connecting portion 32, the second body 40, and the check valve 50, it is preferable to form a corrosion inhibitor coating layer in a predetermined range, particularly including the male thread 32X of the connecting portion 32, the female thread 40A of the second body 40, the valve element 80, and the contact point between the second body 40 and the valve seat 70. However, from the viewpoint of suppressing deterioration of the adhesive performance between the mounting portion 31 and the packaging materials 111, 112 due to the electrolyte, it is meaningful to apply such a coating particularly to the mounting portion 31. The material of the corrosion inhibitor is not particularly limited, but an acid-resistant material is preferable, and the corrosion inhibitor coating layer can be formed by a chromate chromate treatment, a chromate phosphate treatment, or the like.

[0061] [2. Second Embodiment] In the second embodiment, the configuration of the valve structure 10 is different from that of the first embodiment. Other configurations are basically the same as those of the first embodiment. In the following, the same components as those of the first embodiment are denoted by the same reference numerals, and their description will be omitted, and the description will focus on the parts that are different from the first embodiment.

[0062] 10 is a cross-sectional view of a valve structure 200 of the second embodiment. In this embodiment, a multi-stage structure 290 is formed in the insertion hole 71 of the valve seat 70. The surface of the base 81 of the valve body 80 is a generally smooth surface.

[0063] As shown in FIGS. 10 and 11 , the insertion hole 71 of the valve seat 70 has a multi-stage structure 290 including a plurality of convex portions 291 and a plurality of concave portions 292. Such a multi-stage structure 290 can be realized, for example, by forming concave portions 292 in the insertion hole 71. The convex portions 291 and the concave portions 292 are alternately arranged in the direction in which the central axis C1 extends. The convex portions 291 and the concave portions 292 are formed all over the insertion hole 71 in the circumferential direction. The number of convex portions 291 in the multi-stage structure 290 can be selected arbitrarily as long as it is two or more. In this embodiment, the multi-stage structure 290 has six convex portions 291. The number of concave portions 292 in the multi-stage structure 290 is determined, for example, based on the number of convex portions 291. In this embodiment, the multi-stage structure 290 has six concave portions 292.

[0064] When the check valve 50 is in the closed state, the insertion portion 82 is inserted into the insertion hole 71, and the protrusions 291 of the multi-stage structure 290 formed in the insertion hole 71 contact the surface of the insertion portion 82. In this embodiment, the multi-stage structure 290 has six protrusions 291, so when the check valve 50 is in the closed state, the valve seat 70 and the valve element 80 contact each other at six locations. Therefore, when the biasing force of the spring 60 is the same, the valve seat 70 and the valve element 80 contact each other with stronger pressure in this embodiment than when the valve seat 70 and the valve element 80 are in surface contact at one location. Therefore, when the check valve 50 is in the closed state, if the atmosphere and the moisture contained therein enter the valve structure 10 through the outlet 20B, the check valve 50 prevents the moisture from entering the container 110A beyond the check valve 50. This prevents the atmosphere and the moisture contained therein from entering the container 110A.

[0065] <3. Modifications> The above-described embodiments are examples of possible forms of the valve structure for an electricity storage device and the electricity storage device according to the present invention, and are not intended to limit the forms. The valve structure for an electricity storage device and the electricity storage device according to the present invention may take forms different from those exemplified in the embodiments. Examples of such forms include forms in which part of the configuration of each embodiment is replaced, modified, or omitted, or forms in which a new configuration is added to each embodiment. Some examples of modified forms of each embodiment are shown below. Note that the gist of the following modified forms can be applied to the second embodiment as well as the first embodiment.

[0066] <3-1> The configurations of the valve seat 70 and the valve body 80 are not limited to those shown in the respective embodiments, and can be changed as desired.

[0067] FIG. 12 is a cross-sectional view showing a modified valve seat 370 and valve body 380. The modified valve seat 370 is cylindrical. A multi-stage structure 390 is formed on an upper surface 371 of the valve seat 370. The multi-stage structure 390 has multiple protrusions 391 and multiple recesses 392. The valve body 380 has a cylindrical base 381 and a cylindrical shaft 382 extending from an upper surface 381A of the base 381 toward the side opposite the valve seat 370. A lower surface 381B of the base 381 is generally smooth. When the check valve 50 is in a closed state, the lower surface 381B of the base 381 contacts the multiple protrusions 391. The multi-stage structure may be formed on the lower surface 381B of the base 381. In this case, the upper surface 371 of the valve seat 370 may be smooth.

[0068] FIG. 13 is a cross-sectional view showing a valve seat 470 and a valve body 480 of another modified example. The valve seat 470 of this modified example is cylindrical and has an insertion hole 471 into which a portion of the valve body 480 is inserted when the check valve 50 is in a closed state. A multi-stage structure 490 is formed on a side surface 471A of the insertion hole 471. The multi-stage structure 490 has a plurality of convex portions 491 and a plurality of concave portions 492. The valve body 480 has a cylindrical base 481 and a cylindrical shaft portion 482 extending from an upper surface 481A of the base 481 toward the side opposite the valve seat 470. At least a side surface 481C of the surface of the base 481 is a smooth surface. In this embodiment, the entire surface of the base 481 is a smooth surface. When check valve 50 is in the closed state, lower surface 481B of base 481 contacts bottom surface 471B of insertion hole 471, and side surface 481C contacts multiple protrusions 491. Note that a multi-step structure may be formed on side surface 481C of base 481. In this case, side surface 471A of insertion hole 471 is a smooth surface.

[0069] <3-2> The configurations of the multi-stage structures 90, 290 are not limited to those shown in the respective embodiments and can be modified as desired. For example, in the first embodiment, in addition to the multi-stage structure 90 formed on the valve body 80, the multi-stage structure 290 formed on the valve seat 70 shown in the second embodiment can be added. In this modification, when the check valve 50 is in the closed state, the convex portion 91 of the multi-stage structure 90 formed on the valve body 80 fits into the concave portion 292 of the multi-stage structure 290 formed on the valve seat 70. Similarly, the convex portion 291 of the multi-stage structure 290 formed on the valve seat 70 fits into the concave portion 92 of the multi-stage structure 90 formed on the valve body 80.

[0070] <3-3> It is sufficient that the valve seat 70 and the valve element 80 are in contact at multiple points when the check valve 50 is in the closed state. For this reason, for example, in the first embodiment, multiple protrusions protruding from the surface of the insertion portion 82 may be provided instead of the multi-stage structure 90. Similarly, in the second embodiment, multiple protrusions protruding from the inner surface 71A of the insertion hole 71 may be provided instead of the multi-stage structure 290.

[0071] <3-4> The configuration of the peripheral seal portion 150 is not limited to those shown in each embodiment and can be modified as desired. As shown in FIG. 14, the peripheral seal portion 150 may have sloped seal portions 151, 152 whose seal width narrows as they approach the valve structure 10. As shown in FIG. 15, the peripheral seal portion 150 may have sloped seal portions 251, 252 that slope toward a valve seal portion 253 where the valve structure 10 and the packaging materials 111, 112 are sealed. As shown in FIG. 16, the peripheral seal portion 150 may have stepped sloped seal portions 351, 352 that slope toward a valve seal portion 353 where the valve structure 10 and the packaging materials 111, 112 are sealed. As shown in FIG. 17, the peripheral seal portion 150 may have sloped seal portions 451, 452 that slope toward the valve structure 10 and have a substantially constant seal width. According to the modified examples shown in FIGS. 14 to 17, gas generated in the internal space S1 is guided toward the valve structure 10, and therefore the gas can be suitably discharged via the valve structure 10.

[0072] <3-5> As shown in FIG. 18, the valve structure 10 may include a liquid 500 arranged to contact the valve element 80 and the valve seat 70 in order to prevent moisture from entering the internal space S1 (see FIG. 1). The area surrounded by an ellipse in FIG. 18 is an example of the area in which the liquid 500 exists. The type of liquid 500 can be selected arbitrarily. In this embodiment, the liquid 500 is liquid paraffin. Liquid oil such as silicone oil, or an ionic liquid, etc., can also be used as the liquid 500. In a preferred example, the liquid 500 preferably has the property of existing as a liquid under the normal usage environment of the electricity storage device 100. From this perspective, the melting point of the liquid 500 is preferably 10°C or lower, and more preferably 0°C or lower. Similarly, the boiling point of the liquid 500 is preferably 150°C or higher.

[0073] The viscosity of the liquid 500 can be selected arbitrarily. In a preferred example, the viscosity of the liquid is determined based on the viewpoint of favorable gas permeability and handling. A preferred example of the maximum viscosity of the liquid 500 is 2000 mPa·s. When the viscosity of the liquid 500 is 2000 mPa·s or less, the gas can be favorably permeated. A more preferred example of the maximum viscosity of the liquid 500 is 500 mPa·s. A more preferred example of the maximum viscosity of the liquid 500 is 100 mPa·s. A preferred example of the minimum viscosity of the liquid 500 is 0.1 mPa·s. When the viscosity of the liquid 500 is 0.1 mPa·s or more, the liquid can be favorably handled. A more preferred example of the minimum viscosity of the liquid 500 is 0.5 mPa·s. A more preferred example of the minimum viscosity of the liquid 500 is 1.0 mPa·s. An example of a preferred range of the viscosity of the liquid 500 is 0.1 mPa·s to 2000 mPas. An example of a more preferred range of the viscosity of the liquid 500 is 0.5 mPa·s to 500 mPas. An example of a more preferred range of the viscosity of the liquid 500 is 1.0 mPa·s to 100 mPas. The viscosity of the liquid 500 is measured in a temperature range of 10°C to 40°C. When the liquid 500 is crude oil or petroleum, the viscosity of the liquid 500 is calculated by multiplying the kinematic viscosity measured in accordance with "JIS K2283 Crude oil and petroleum products - Kinematic viscosity test method and viscosity index calculation method" by the density. When the liquid 500 is other than crude oil or petroleum, the viscosity of the liquid 500 is measured in accordance with "JIS Z8803 Method for measuring viscosity of liquids."

[0074] The specific arrangement of the liquid 70 can be selected arbitrarily as long as the liquid 70 is in contact with the valve element 52 and the valve seat 53. In the example shown in Fig. 18, the liquid 70 is arranged so as to adhere to at least the portion of the surface of the valve element 80 that is in contact with the valve seat 70 and the portion of the surface of the valve seat 70 that is in contact with the valve element 80 when the check valve 50 is in the closed state. In another example, the liquid 500 is filled within a predetermined range of the accommodation space S2.

[0075] <3-6> Although container 110A is constructed by heat-sealing packaging material 111 and packaging material 112, container 110A may also be constructed by folding a single sheet of packaging material and heat-sealing the peripheral edge.

[0076] <3-7> The container 110A may be made of the packaging materials 111 and 112 as described above, but may also be, for example, a metal can. [Explanation of symbols]

[0077] 10, 200: Valve structure for power storage device 20: Valve body 42: Side wall 42B: Discharge hole 50: Check valve 70, 370, 470: Valve seat 71: Insertion hole 80, 380, 480: Valve body 82: Insertion section 100: Energy storage device 110A: Container 120: Energy storage device element 90, 290: Multi-stage structure LA:Aisle

Claims

1. a passageway that connects the inside and outside of a container that accommodates the electricity storage device element; a check valve that is disposed to close the passage and that opens when the internal pressure of the container increases due to gas generated inside the container, thereby allowing the gas to pass from the inside to the outside of the container, the check valve includes a valve seat and a valve body that contacts the valve seat in a closed state; the valve seat and the valve body are in contact with each other at a plurality of points in the closed state, the check valve is configured such that, when the internal pressure of the container increases in the closed state, the valve element moves in a direction away from the valve seat, thereby forming a gap between the valve element and the valve seat, At least one of the valve seat and the valve body includes a multi-step structure having a plurality of steps, The valve seat and the valve body are in contact with each other via the multi-stage structure in the closed state. Valve structure for power storage device.

2. A passage that connects the inside and outside of a container that houses an electricity storage device element; a check valve that is disposed to close the passage and that opens when the internal pressure of the container increases due to gas generated inside the container, thereby allowing the gas to pass from the inside to the outside of the container, the check valve includes a valve seat and a valve body that contacts the valve seat in a closed state; the valve seat and the valve body are in contact with each other at a plurality of points in the closed state, the check valve is configured such that, when the internal pressure of the container increases in the closed state, the valve element moves in a direction away from the valve seat, thereby forming a gap between the valve element and the valve seat, the valve seat includes an insertion hole into which the valve body is inserted in the closed state, the valve body includes an insertion portion that is inserted into the insertion hole in the closed state, The insertion hole has a shape that tapers toward the inside of the container, The insertion portion has a shape that tapers toward the inside of the container so as to conform to the shape of the insertion hole. Valve structure for power storage device.

3. A passage that connects the inside and outside of a container that houses an electricity storage device element; a check valve that is disposed to close the passage and that opens when the internal pressure of the container increases due to gas generated inside the container, thereby allowing the gas to pass from the inside to the outside of the container, the check valve includes a valve seat and a valve body that contacts the valve seat in a closed state; the valve seat and the valve body are in contact with each other at a plurality of points in the closed state, the check valve is configured such that, when the internal pressure of the container increases in the closed state, the valve element moves in a direction away from the valve seat, thereby forming a gap between the valve element and the valve seat, Further comprising a valve body that houses the check valve; The valve body includes a side wall that guides the movement of the valve element when the check valve transitions from one of the closed state and the open state to the other. Valve structure for power storage device.

4. The sidewall includes a vent hole formed therein to allow the gas to be vented when the check valve is in the open state. The valve structure for an electricity storage device according to claim 3 .

5. A passage that connects the inside and outside of a container that houses an electricity storage device element; a check valve that is disposed to close the passage and that opens when the internal pressure of the container increases due to gas generated inside the container, thereby allowing the gas to pass from the inside to the outside of the container, the check valve includes a valve seat and a valve body that contacts the valve seat in a closed state; the valve seat and the valve body are in contact with each other at a plurality of points in the closed state, the check valve is configured such that, when the internal pressure of the container increases in the closed state, the valve element moves in a direction away from the valve seat, thereby forming a gap between the valve element and the valve seat, a liquid disposed in contact with the valve seat and the valve body; Valve structure for power storage device.

6. The melting point of the liquid is 10°C or less. The valve structure for an electricity storage device according to claim 5 .

7. The boiling point of the liquid is 150°C or higher. The valve structure for an electricity storage device according to claim 5 or 6.

8. The liquid includes liquid paraffin The valve structure for an electricity storage device according to any one of claims 5 to 7.

9. The viscosity of the liquid is in the range of 0.1 mPa·s to 2000 mPa·s. The valve structure for an electricity storage device according to any one of claims 5 to 8.

10. The valve structure for an electricity storage device according to any one of claims 1 to 9, the container to which the valve structure for an electricity storage device is attached; Energy storage device.

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