JP7586038B2 - Valve structure for power storage device and power storage device - Google Patents

Description

The present invention relates to a valve structure for an electricity storage device and an electricity storage device equipped with the same.

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 seal 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.

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 off than other portions. The easy-peel portion peels off 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 a check valve as in Patent Document 1, the easy-peel portion is a break valve that does not return to its original state once peeled off.

JP 2016-31934 A JP 2010-153841 A

A check valve is generally a one-way valve whose purpose is to prevent backflow. However, in a battery such as that in Patent Document 1, even a small amount of air entering the pouch can cause deterioration of the battery, so it is necessary to prevent backflow with greater precision. For this reason, it is practically difficult for a check valve that releases gas from within a pouch such as that in Patent Document 1 to completely prevent air from entering the pouch to the high level required for a battery. Therefore, in a battery such as that in Patent Document 1, there is a problem in that air can enter the pouch, causing deterioration of the battery.

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 that air enters the laminated container, causing deterioration of the battery.

The present invention aims to provide a valve structure that can prevent air from entering a container that houses an electricity storage device element, and an electricity storage device that includes the valve structure.

The 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 close 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, the check valve including a valve seat and a valve body, and a liquid that is arranged to contact the valve seat and the valve body.

The valve structure for an electricity storage device according to the second aspect of the present invention is the valve structure for an electricity storage device according to the first aspect, in which the melting point of the liquid is 10°C or less.

The valve structure for an electricity storage device according to the third aspect of the present invention is the valve structure for an electricity storage device according to the first or second aspect, in which the boiling point of the liquid is 150°C or higher.

The 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, in which the liquid includes liquid paraffin.

The valve structure for an electricity storage device according to a fifth aspect of the present invention is a valve structure for an electricity storage device according to any one of the first to fourth aspects, in which 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 a sixth aspect of the present invention is a valve structure for an electricity storage device according to any one of the first to fifth aspects, in which the passage includes an outlet facing the external space and has a sealing member attached to close the outlet.

The seventh aspect of the present invention relates to a valve structure for an electricity storage device according to any one of the first to sixth aspects, and has a cover material that is arranged on at least one of the primary and secondary sides of the check valve and is configured to allow the gas to pass through.

The electricity storage device according to the eighth aspect of the present invention comprises a valve structure for an electricity storage device according to any one of the first to seventh aspects, and the container to which the valve structure for an electricity storage device is attached.

The valve structure for an electricity storage device and the electricity storage device of the present invention can prevent air from entering the container that houses the electricity storage device element.

1 is a plan view of an electricity storage device including a valve structure for an electricity storage device according to a first embodiment; FIG. 2 is a cross-sectional view taken along line D2-D2 in FIG. FIG. 2 is a front view of the valve structure of FIG. 1 . FIG. 4 is a bottom view of the valve structure of FIG. 3 . FIG. 4 is a plan view of the valve structure of FIG. 3 . FIG. 4 is a perspective view of the valve structure of FIG. 3 as viewed from the rear side. 7 is a cross-sectional view taken along line D7-D7 in FIG. 4. FIG. 7B is a cross-sectional view of the seal member of FIG. 7A. 4 is a cross-sectional view taken along line D8-D8 in FIG. 3; FIG. 13 is a front view of a valve structure for an electricity storage device according to a second embodiment. 10 is a cross-sectional view taken along line D10-D10 in FIG. 9 . FIG. 11 is a cross-sectional view of a valve structure according to a modified example. FIG. 13 is a cross-sectional view of a valve structure according to another modified example. FIG. 13 is a cross-sectional view of a valve structure according to still another modified example. FIG. 13 is a plan view of an electricity storage device according to a modified example. FIG. 13 is a plan view of an electricity storage device according to another modified example. FIG. 13 is a plan view of an electricity storage device according to still another modified example. FIG. 13 is a plan view of an electricity storage device according to still another modified example.

The following describes a valve structure for an electricity storage device according to one embodiment of the present invention, an electricity storage device including the valve structure, and a method for manufacturing the same, with reference to the drawings.

[1. First embodiment]
<1-1. Overall configuration of electricity storage device>
Fig. 1 shows a plan view of an electricity storage device 100 including an electricity storage device valve structure 10 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 by 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 this.

The energy storage device 100 comprises a housing 110, an energy storage device element 120, a tab 130, and a tab film 140. The housing 110 comprises an internal space S1 and a peripheral seal portion 150. The energy 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 energy storage device element 120, and the other end protrudes outward from the peripheral seal portion 150 of the housing 110, and a portion between the one end and the other end is fused to the peripheral seal portion 150 via the tab film 140.

The container 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 to each other at 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 seal mode referred to here may be a mode such as heat fusion from a heat source or ultrasonic fusion. 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 150 that sandwiches the tab 130 and the tab film 140 is made up of the packaging material 112, the tab 130, the pair of tab films 140, and the packaging material 111, which are integrated together, while the portion of the peripheral seal 150 that sandwiches only the pair of tab films 140 is made up of the packaging material 112, the pair of tab films 140, and the packaging material 111, which are integrated together.

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 a method such as injection molding, compressed air molding, vacuum molding, or blow molding, and in-mold molding may be performed to impart design and functionality. The type of resin may be polyolefin, polyester, nylon, ABS, or the like. The film referred to here is, for example, a resin film that can be manufactured by a method such as an inflation method or a T-die method, or a film in which such a resin film is laminated on a metal foil. The film referred to here may or may not be stretched, and may be a single-layer film or a multilayer film. The multilayer film referred to here may be manufactured by a coating method, may be a film in which multiple films are bonded together with an adhesive, or may be manufactured by a multilayer extrusion method.

As described above, the packaging materials 111 and 112 can be configured in various ways, but in this embodiment, they are configured from a laminate film. The laminate film can be a laminate in which a base layer, a barrier layer, and a heat-sealable resin layer are laminated. The base layer functions as a base material for the packaging materials 111 and 112, and is typically an insulating resin layer that forms the outer layer side of the container 110A. The barrier layer not only improves the strength of the packaging materials 111 and 112, but also has the function of preventing 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.

The shape of the container 110A is not particularly limited, and can be, for example, a bag-like (pouch-like) shape. The bag-like shape here can be a three-sided seal type, a four-sided seal type, a pillow type, a gusset type, or the like. However, the container 110A of this embodiment has a shape as shown in FIG. 2, and is manufactured by heat-sealing a packaging material 111 formed into a tray shape and a packaging material 112 similarly formed into a tray shape and superimposed on the packaging material 111 along the outer periphery in a plan view. The packaging material 111 includes a square ring-shaped 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 the flange portion 111A and bulges downward from there. Similarly, the packaging material 112 includes a square ring-shaped 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 the flange portion 112A and bulges upward from there. 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 be integrated, forming peripheral seal portion 150. Peripheral seal portion 150 extends around the entire outer periphery of container 110A and is formed in a rectangular ring shape. Note that one of packaging materials 111 and 112 may be in sheet form.

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

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 of which constitutes a positive terminal and the other of which constitutes a negative terminal. One left and right end of each tab 130 is electrically connected to an electrode (positive or negative) 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-mentioned form of the power storage device 100 is particularly preferable for use in electric vehicles such as electric vehicles and hybrid vehicles that use a large number of power storage devices 100 connected in series at high voltage. The attachment positions of the two tabs 130 that constitute the positive and negative terminals are not particularly limited, and may be arranged on the same side of the peripheral seal portion 150, for example.

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.

The left tab 130 is sandwiched between the packaging materials 111, 112 at the left end of the peripheral seal portion 150 via the tab film 140. The right tab 130 is also sandwiched between the packaging materials 111, 112 at the right end of the peripheral seal portion 150 via the tab film 140.

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 by being fused and fixed to the tab 130 in advance, and the tab 130 to which the tab film 140 is fixed is sandwiched between the packaging materials 111, 112 and fused to be integrated as shown in FIG. 2.

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, causing damage to the power storage device 100. The container 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.

<1-2. Configuration of valve structure>
FIG. 3 is a front view of the valve structure 10. The valve structure 10 includes a valve main body 20 and a liquid 70 (see FIGS. 7A and 8). The valve main body 20 includes a first body 30, a second body 40, a check valve 50 (see FIGS. 7A and 8), a seal member 80, and a lid member 90 (see FIGS. 7A and 8). In this embodiment, the first body 30 and the second body 40 are arranged in succession in the order of the direction from the inside to the outside of the container 110A (see FIG. 1) (direction from the rear side to the front side). FIG. 4 is a view of the valve structure 10 viewed from the first body 30 side (from the rear side). FIG. 5 is a view of the valve structure 10 viewed from the second body 40 side (from the front side). FIG. 6 is a perspective view of the valve structure 10 viewed from the first body 30 side (from the rear side).

Figure 7A is a cross-sectional view taken along line D7-D7 in Figure 4. Figure 8 is a cross-sectional view taken along line D8-D8 in Figure 3. As shown in Figures 7A and 8, 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 Figure 1) rises due to gas generated inside the container 110A, and allows the gas to pass from the inside to the outside of the container 110A. More specifically, the check valve 50 constitutes a relief valve that switches between an open state and a closed state depending on the pressure on its primary side, that is, the pressure in the internal space S1 (see Figure 1). A passage LA is formed in the accommodation space S2 inside the valve body 20. The passage LA is a passage that 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.

The check valve 50 is positioned so as to block 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 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.

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. The attachment portion 31 is heat-sealed together with the packaging materials 111, 112 via a heat-sealing film 60 (see FIG. 1) when the container 110A is molded. This heat sealing causes the outer peripheral surface of the attachment portion 31 and the packaging materials 111, 112 to be fused and joined via the heat-sealing film 60, and the attachment portion 31 is fixed to the peripheral seal portion 150 in such a manner that it is sandwiched between the packaging materials 111, 112 (see FIG. 2).

The connecting portion 32 is disposed outside the peripheral seal portion 150 and is not sandwiched between the packaging materials 111, 112 (see Figures 1 and 2). The second body 40, which is disposed further outboard 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 destroyed 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.

The mounting portion 31, the connecting portion 32, and the second body 40 extend coaxially with each other. The mounting portion 31, the connecting portion 32, and the second body 40 have a common central axis C1. The mounting 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 with each other, with the central axis C1 as the central axis. In this embodiment, the inlet 20A and the outlet 20B are arranged on the end surface in the front-rear direction, not on the outer peripheral surface of the valve body 20, and in particular, the central axis C1 extending linearly in the front-rear direction passes through the centers of the inlet 20A and the outlet 20B. Although not limited thereto, the cross section perpendicular to the central axis C1 of the air passages LX to LZ is circular. The air passages LX to LZ are connected to each other and together form a passage LA. The third air passage LZ is disposed closer to the outside of the container 110A than the first air passage LX. The second air passage LY is disposed even closer to the outside of the container 110A than the third air passage LZ.

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 thinner from the center in the left-right direction toward the left, and a second wing-shaped portion 31B that is thinner toward the right, when viewed along the direction in which the central axis C1 extends. For this reason, 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.

In this embodiment, since the first wing-shaped portion 31A and the second wing-shaped portion 31B are formed, the outer peripheral surface of the mounting portion 31 has 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. In addition, for example, compared to a case in which 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 in the vertical direction of the electric storage device 100 at the position where the mounting portion 31 is sandwiched in the peripheral seal portion 150 from the portion where the mounting portion 31 is not sandwiched to the portion where the mounting portion 31 is sandwiched in the peripheral seal portion 150. As a result, no excessive force is applied to the packaging materials 111 and 112 in the peripheral portion of the position where the mounting portion 31 is attached in the peripheral seal portion 150. Therefore, the mounting portion 31 can be firmly fixed to the peripheral seal portion 150 via the heat-sealing film 60.

The outer shape of the connecting portion 32 is generally a shape of a cylinder with the central axis C1 as the central axis, with a portion cut out. More specifically, the outer shape of the connecting portion 32 is generally a shape of a cylinder with the central axis C1 as the central axis, with a plane cut out at a certain distance from the central axis C1, and with a plane further cut out at a position symmetrical to the plane with respect to the central axis C1. Thus, the connecting portion 32 has a pair of planes, the first plane 32A and the second plane 32B. The first plane 32A and the second plane 32B are parallel to each other (including the case where they are approximately parallel. The same applies below). The first plane 32A and the second plane 32B are parallel to the direction in which the central axis C1 extends (including the case where they are approximately parallel. The same applies below). 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 the case where they are approximately parallel. The same applies below). The outer circumferential surface of the connecting portion 32 is composed of a first plane 32A, a second plane 32B, and curved surfaces 32C and 32D that connect the first plane 32A and the second plane 32B. When viewed along the direction in which the central axis C1 extends, the curved surfaces 32C and 32D are each an arc shape centered on the central axis C1, and overlap with 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 plane 32A and the second plane 32B.

The second body 40 is cylindrical and defines an accommodation space S2 that accommodates the check valve 50 together with the first body 30. The first body 30 and the second body 40 are assembled with the check valve 50 accommodated in the accommodation space S2. The first body 30 and the second body 40 are joined together by, for example, at least one of bonding with an adhesive, bonding with a screw structure, and bonding with a concave-convex meshing. In this embodiment, the first body 30 and the second body 40 are joined together by the meshing of the male thread 32X (see FIG. 7A) formed on the outer surface of the connecting portion 32 of the first body 30 and the female thread 40A (see FIG. 7A) formed on the inner surface of the second body 40, and by the adhesive applied to the male thread 32X and the female thread 40A. The material of the adhesive is not particularly limited, but may be composed of an acid-modified polyolefin and an epoxy resin. This type of adhesive is superior to adhesives made of modified silicone resin, for example, in that it can suppress deterioration of adhesive performance due to the electrolyte contained in the container 110A. Any means can be used to join the first body 30 and the second body 40. Therefore, in this embodiment, at least one of the structure related to the meshing of the male thread 32X and the female thread 40A and the adhesive may be omitted.

As described above, in this embodiment, the outer shapes of the attachment 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.

The second body 40 holds a portion having a main structure for performing the function of the valve structure 10 as a gas vent valve. In this embodiment, the check valve 50 has a spring 51, a valve body 52, and a valve seat 53 as a valve mechanism housed in the second air passage LY inside the second body 40. The spring 51, the valve body 52, and the valve seat 53 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 Figures 7A and 8, the first body 30 and the valve seat 53 are configured as separate parts, but they may be configured as an integral part.

The valve seat 53 receives the valve body 52 biased from the outside by the spring 51, and at this time, the valve structure 10 is in a closed state. The spring 51 is, for example, a coil spring, but is not limited to this, and can be, for example, a leaf spring. In this embodiment, the valve seat 53 is cylindrical and extends about the central axis C1, and has a top surface 53A that defines the front end surface in the front-rear direction, and a bottom surface 53B that defines the rear end surface. The valve body 52 is, for example, ball-shaped. A part of the surface of the valve body 52 is received by the top surface 53A of the valve seat 53, and contacts the top surface 53A when the check valve 50 is in a closed state. The spring 51 extends in a spiral shape about the central axis C1. The spring 51 is connected to the valve body 52.

The valve seat 53 and the first body 30 can be bonded, for example, with an adhesive. There are no particular limitations on the material of the adhesive, but a preferred example in which the valve seat 53 is made of fluororubber and the first body 30 is made of a metal such as aluminum is the same adhesive as exemplified when joining the first body 30 and the second body 40. In addition, from the viewpoint 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.

The mounting portion 31 is fixed to the peripheral seal portion 150 so that the gas generated in the internal space S1 of the container 110A flows into the first ventilation path LX. That is, the first ventilation path 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 that flows out of the internal space S1 and passes through the first ventilation path LX and the third ventilation path LZ presses the valve body 52 toward the outlet 20B. When the valve body 52 is pressed and moves away from the valve seat 53, the spring 51 deforms, and the valve body 52 moves toward the outlet 20B, forming an open state of the check valve 50. In this open state, the gas generated in the internal space S1 flows toward the outlet 20B through the gap formed between the valve body 52 and the valve seat 53, and is discharged to the external space. In this way, when the gas in the internal space S1 is discharged through the passage LA, the pressure on the internal space S1 side pressing the valve body 52 toward the outlet 20B side weakens, and the force of the spring 51 urging the valve body 52 toward the inlet 20A side becomes greater. As a result, the shape of the spring 51 is restored, and the check valve 50 is closed again.

When the check valve 50 is closed, it can prevent the atmosphere from entering the internal space S1 of the container 110A from the external space. Once the check valve 50 is opened, the internal space S1 is kept at a relatively high pressure equal to or higher than atmospheric pressure, so that the atmosphere is unlikely to enter the internal space S1. The valve structure 10 can effectively prevent the atmosphere from entering the internal space S1 by using the check valve 50 described above, and prevent deterioration of the electricity storage device element 120 due to moisture contained therein. Even when the check valve 50 is open, the atmosphere 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 higher than or equal to the pressure on the secondary side.

The liquid 70 shown in Figures 7A and 8 is placed in the storage space S2. The hatched area shown in Figures 7A and 8 is an example of the area in which the liquid 70 exists.

The liquid 70 is arranged to be in contact with the valve body 52 and the valve seat 53 in order to prevent the air from entering the internal space S1 (see FIG. 1). The type of liquid 70 can be selected arbitrarily. In this embodiment, the liquid 70 is liquid paraffin. Liquid oil such as silicone oil, or ionic liquid, etc. can also be used as the liquid 70. In a preferred example, the liquid 70 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 70 is preferably 10° C. or less, and more preferably 0° C. or less. Similarly, the boiling point of the liquid 70 is preferably 150° C. or more.

The viscosity of the liquid 70 can be selected arbitrarily. In a preferred example, the viscosity of the liquid is determined based on the viewpoint of allowing gas to permeate suitably and the viewpoint of handling. A preferred example of the maximum viscosity of the liquid 70 is 2000 mPa·s. When the viscosity of the liquid 70 is 2000 mPa·s or less, the gas can be permeated suitably. A more preferred example of the maximum viscosity of the liquid 70 is 500 mPa·s. A more preferred example of the maximum viscosity of the liquid 70 is 100 mPa·s. A preferred example of the minimum viscosity of the liquid 70 is 0.1 mPa·s. When the viscosity of the liquid 70 is 0.1 mPa·s or more, the liquid 70 can be handled suitably. A more preferred example of the minimum viscosity of the liquid 70 is 0.5 mPa·s. A more preferred example of the minimum viscosity of the liquid 70 is 1.0 mPa·s. An example of a preferred range of the viscosity of the liquid 70 is 0.1 mPa·s to 2000 mPas. An example of a more preferred range of the viscosity of the liquid 70 is 0.5 mPa·s to 500 mPas. An example of a more preferred range of the viscosity of the liquid 70 is 1.0 mPa·s to 100 mPas. The viscosity of the liquid 70 is a viscosity in a measurement range of 10°C to 40°C. In addition, when the liquid 70 is crude oil or petroleum, the viscosity of the liquid 70 is a viscosity calculated by multiplying the kinematic viscosity measured based on "JIS K2283 Crude oil and petroleum products - Kinematic viscosity test method and viscosity index calculation method" by the density. When the liquid 70 is other than crude oil or petroleum, the viscosity of the liquid 70 is a viscosity measured based on "JIS Z8803 Viscosity measurement method for liquids".

The specific arrangement of the liquid 70 can be selected arbitrarily as long as the liquid 70 is in contact with the valve body 52 and the valve seat 53. In this embodiment, the liquid 70 is filled in a predetermined range of the storage space S2. For example, the liquid 70 is filled from at least one of the inlet 20A and the outlet 20B after the first body 30 and the second body 40 are assembled. According to this embodiment, when the check valve 50 is in an open state, the gas generated in the internal space S1 (see FIG. 1) flows out from the gap formed between the valve body 52 and the valve seat 53. The flowing gas passes through the liquid 70 in the form of bubbles, and after passing through the liquid 70, flows out toward the outlet 20B. On the other hand, when the atmosphere and the moisture contained therein enter the valve structure 10 through the outlet 20B, the moisture and the like are prevented from entering the inside of the container 110A beyond the check valve 50 by the liquid 70. Therefore, the atmosphere and the moisture and the like contained therein are suppressed from entering the container 110A. As shown in Fig. 11, the liquid 70 may at least adhere to the portion of the surface of the valve body 52 that contacts the valve seat 53 and the portion of the surface of the valve seat 53 that contacts the valve body 52 when the check valve 50 is closed. Such an arrangement of the liquid 70 can be formed, for example, by injecting air from the inlet 20A to blow away the liquid 70 in the state shown in Fig. 7A. In the arrangement of the liquid 70 shown in Fig. 11, the liquid 70 forms a film on the portion of the surface of the valve body 52 that contacts the valve seat 53 and the portion of the surface of the valve seat 53 that contacts the valve body 52 when the check valve 50 is closed. When the check valve 50 is open, the gas generated in the internal space S1 passes through the film of the liquid 70 in the form of bubbles, or breaks through the film of the liquid 70 and flows out toward the outlet 20B. When gas breaks through the film of liquid 70, the check valve 50 transitions from an open state to a closed state, causing the valve body 52 and the valve seat 53 to come into contact, and the film of liquid 70 is regenerated.

The materials constituting each part of the valve structure 10 are not particularly limited. As a preferred example, the valve body 52 can be made of a fluororesin such as polytetrafluoroethylene (PTFE), and the valve seat 53 can be made of a fluororubber such as polyvinylidene fluoride (FKM). Furthermore, the spring 51 can be made of a metal such as stainless steel, and the mounting part 31, the second body 40, and the connecting part 32 can be made of a metal such as aluminum alloy, stainless steel, steel plate, titanium, etc. Furthermore, the valve body 52 can be made of a metal such as stainless steel, or a fluororubber such as FKM. Note that when the valve body 52 is made of a fluororubber such as FKM, it is preferable that the valve seat 53 is made of a fluororesin such as PTFE.

The heat-sealing film 60 shown in FIG. 1 and the like is configured to be adhered to both the valve structure 10 and the packaging materials 111, 112 of the container 110A by heat sealing. The heat-sealing film 60 is fused to the mounting 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. 7A). The heat-sealing film 60 is fused to the mounting portion 31 so as to cover most of the surface of the mounting portion 31. As the heat-sealing film 60, various known adhesive films can be adopted. The heat-sealing film 60 may be, for example, a single-layer film of maleic anhydride-modified polypropylene (PPa), or a laminated film of multiple layers of PPa, polyethylene naphthalate (PEN), and PPa. A laminated film of multiple layers of PPa, polypropylene (PP), and PPa may also be applied. In addition, 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-sealing film 60 is a three-layer laminate film including a core material, which is made of PPa/polyester fiber/PPA. As the core material, various known materials can be used 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 may be polyamide fiber, or may be carbon fiber.

In addition, it is preferable to apply a coating of a corrosion inhibitor to the surface of the mounting portion 31 to form a corrosion-preventing film layer, particularly from the viewpoint of electrolyte resistance. This is particularly true when the mounting portion 31 is made of a metal such as aluminum, but it can also be true when the mounting portion 31 is made of other materials. Such a coating can be applied by immersing the mounting portion 31 in a liquid of the corrosion inhibitor 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, and prevents 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. In addition, particularly from the viewpoint of electrolyte resistance, a similar coating may be applied to the surfaces of not only the mounting portion 31 but also the connecting portion 32, the second body 40, and the check valve 50 to form a corrosion-preventing film layer. When applying a coating of a corrosion inhibitor to the surfaces of the connecting portion 32, the second body 40, and the check valve 50, it is preferable to form a corrosion-preventing 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 body 52, and the contact point between the second body 40 and the valve seat 53. However, from the viewpoint of suppressing deterioration of the adhesive performance between the mounting portion 31 and the packaging materials 111 and 112 due to the electrolyte, it is meaningful to apply such a coating to the mounting portion 31 in particular. The material of the corrosion inhibitor is not particularly limited, but an acid-resistant material is preferable, and the corrosion-preventing coating layer can be formed by chromate chromate treatment or phosphate chromate treatment, etc.

The seal member 80 is attached to the second body 40 so as to close the outlet 20B. This prevents, for example, the liquid 70 from leaking through the outlet 20B during transportation of the valve structure 10, and prevents foreign matter from entering the inside of the valve structure 10 through the outlet 20B. When the valve structure 10 is attached to the container 110A, the seal member 80 is peeled off from the second body 40. The seal member 80 shown in FIG. 7B includes, for example, a surface layer 81 that closes the outlet 20B, and a base layer 82 that is laminated on the surface layer 81. The seal member 80 may be an adhesive containing an acrylic resin, or may have a single-layer structure consisting of only the surface layer 81.

The material constituting the surface layer 81 preferably contains at least one of, for example, polyolefin and elastomer. When polyolefin is present on the surface of the surface layer 81, the seal member 80 can be easily peeled off from the second body 40 when the valve structure 10 is in use. The polyolefin is, for example, polyethylene or polypropylene. When the material constituting the surface layer 81 contains an elastomer, the surface layer 81 has adhesiveness, so that the seal member 80 can be easily positioned relative to the outlet 20B. The elastomer is, for example, a thermoplastic elastomer.

The substrate layer 82 includes, for example, a first substrate layer 82A laminated on the surface layer 81, and a second substrate layer 82B laminated on the first substrate layer 82A. The material constituting the first substrate layer 82A preferably includes a metal such as an aluminum alloy, for example, from the viewpoint of improving water vapor barrier properties and airtightness. When the material constituting the first substrate layer 82A includes a metal, the sealing member 80 as a whole has tension, and can be easily peeled off from the second body 40. The second substrate layer 82B is laminated on the first substrate layer 82A, for example, via an adhesive. The material constituting the second substrate layer 82B includes, for example, polyethylene terephthalate.

The lid material 90 is composed of a PTFE (PolyTetraFluoroEthylene) membrane having a pore diameter of, for example, 10 ⁻² μm to 10 ⁰ μm, which does not allow the organic solvent contained in the power storage device element 120 and the liquid 70 to pass through, and selectively allows only gas to pass through. Since the PTFE membrane is a soft material, if the strength is insufficient, the lid material 90 may be reinforced by a mesh of polypropylene or polyester, or a nonwoven fabric and a PTFE membrane integrally molded. The material constituting the lid material 90 may be, for example, a metal mesh, a synthetic resin mesh, or a nonwoven fabric. The lid material 90 includes a first lid material 91 arranged on the primary side of the check valve 50, and a second lid material 92 arranged on the secondary side of the check valve 50.

The first lid material 91 prevents the organic solvent contained in the power storage device element 120 (see FIG. 2) from passing through the passage LA to open the check valve 50 and flow out of the valve body 20. The position of the first lid material 91 in the valve body 20 can be selected arbitrarily as long as it is on the primary side of the check valve 50. In this embodiment, the first lid material 91 is arranged in the passage LA near the bottom surface 53B of the valve seat 53. The first lid material 91 may be arranged in the passage LA near the inlet 20A, or may be arranged at any position between the bottom surface 53B of the valve seat 53 and the inlet 20A.

The second lid material 92 prevents the liquid 70 from leaking through the outlet 20B when the seal member 80 is peeled off, for example, when the valve structure 10 is in use. The second lid material 92 is disposed, for example, near the outlet 20B. The second lid material 92 may be disposed at any position between the liquid level of the liquid 70 and the outlet 20B.

[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, their description is omitted, and the description will focus on the parts that are different from the first embodiment.

Figure 9 is a front view of the valve structure 200 of the second embodiment. Figure 10 is a cross-sectional view taken along line D10-D10 in Figure 9. The second body 40 of this embodiment is configured to hold a plurality of check valves 50. In this embodiment, the second body 40 holds two check valves 50. In the following, in order to distinguish between the two check valves 50, the check valve 50 located closer to the inlet 20A may be referred to as the check valve 210, and the check valve 50 located closer to the outlet 20B may be referred to as the check valve 220.

The check valves 210, 220 are arranged along the direction in which the passage LA extends, and the check valve 220 is disposed on the secondary side (external side) of the check valve 210. When the check valves 210, 220 open, the passage LA can discharge gas generated in the internal space S1 (see FIG. 1) to the outside of the container 110A. Note that the check valves 210, 220 do not necessarily open at the same time, and are often open at different times.

The check valves 210 and 220 are arranged so as to close the passage LA at different positions along the extension direction of the passage LA in the closed state. In this embodiment, the part (valve box) constituting the body included in the check valves 210 and 220 is constituted by the second body 40, and the valve mechanism included in the check valves 210 and 220 is arranged inside the second body 40. The space included in the passage LA and located on the secondary side (external side) of the check valve 210 and the primary side (internal side) of the check valve 220 is called the intervalve space S3. When the pressure of the internal space S1 increases due to gas generated in the internal space S1, the check valve 210 opens and allows the gas to pass from its primary side to its secondary side, i.e., to the intervalve space S3. When the check valve 210 opens and the gas generated in the internal space S1 flows into the intervalve space S3, the pressure of the intervalve space S3 increases. When the pressure in the intervalve space S3 rises in this manner, the check valve 220 opens and allows gas to pass from its primary side to its secondary side, i.e., to the external space. When either the check valve 210 or 220 is in the closed state, the valve structure 200 seals the internal space S1 from the external space.

When the pressure in the internal space S1, i.e., the pressure in the space on the primary side of the check valve 210, reaches a predetermined pressure, the gas that flows out of the internal space S1 and passes through the first air passage LX and the third air passage LZ presses the valve body 52 toward the check valve 220. When the valve body 52 is pressed and separated from the valve seat 53, the spring 51 deforms, and the valve body 52 moves toward the check valve 220, forming an open state of the check valve 210. In this open state, the gas generated in the internal space S1 flows out into the intervalve space S3 through the gap formed between the valve body 52 and the valve seat 53. In this way, when the gas in the internal space S1 is discharged to the secondary side of the check valve 210, the pressure on the internal space S1 side pressing the valve body 52 toward the check valve 220 weakens, and the force of the spring 51 urging the valve body 52 toward the inlet 20A becomes greater. As a result, the spring 51 returns to its original shape, and the check valve 210 is closed again.

When the check valve 210 opens and the pressure in the intervalve space S3 included in the second air passage LY, i.e., the pressure in the space on the primary side of the check valve 220, reaches a predetermined pressure, the gas in the intervalve space S3 presses the valve body 52 toward the outlet 20B. When the valve body 52 is pressed and separated from the valve seat 53, the spring 51 deforms, the valve body 52 moves toward the outlet 20B, and the check valve 220 is opened. In this open state, the gas contained in the intervalve space S3 flows toward the outlet 20B through the gap formed between the valve body 52 and the valve seat 53, and is discharged to the outside space through the outlet 20B. In this way, when the gas in the intervalve space S3 is discharged through the passage LA, the pressure on the intervalve space S3 side pressing the valve body 52 toward the outlet 20B weakens, and the force of the spring 51 urging the valve body 52 toward the check valve 210 becomes greater. As a result, the spring 51 returns to its original shape, and the check valve 220 is closed again.

When closed, the check valves 210 and 220 can prevent the ingress of atmospheric air from the external space into the internal space S1 of the container 110A. In order for the atmospheric air to enter the internal space S1 from the external space, it must flow back through the multiple check valves 210 and 220, making such ingress unlikely. In addition, once the check valve 210 opens, the intervalve space S3 is kept at a relatively high pressure equal to or higher than atmospheric pressure, making it difficult for the atmospheric air to even enter the intervalve space S3 from the external space. Therefore, the valve structure 200 can effectively prevent the ingress of atmospheric air into the internal space S1 by the check valves 210 and 220 arranged in multiple stages along the passage LA, and can prevent deterioration of the electricity storage device element 120 due to moisture contained therein.

Even when the check valves 210, 220 are open, it is difficult for the atmosphere to enter the internal space S1. This is because, in the open state, the pressure on the primary side of each of the check valves 210, 220 is maintained higher than or equal to the pressure on the secondary side.

The opening pressure of the check valves 210 and 220 can be set appropriately, and the opening pressure of the check valve 210 may be (i) equal to the opening pressure of the check valve 220, (ii) lower than the opening pressure of the check valve 220, or (iii) higher than the opening pressure of the check valve 220. However, from the following viewpoint, (i) and (ii) are preferred. In the case of (ii), the pressure of the internal space S1 can be maintained higher, so that the pressure difference between the internal space S1 and the external space more effectively prevents the atmosphere of the external space from entering the internal space S1. In the case of (i), the pressure of the internal space S1 can be maintained relatively high, and the manufacturing of the check valves 210 and 220 is easy, and, for example, there is an advantage that the check valves 210 and 220 are not mixed up. For example, the opening pressure of the check valves 210 and 220 can both be set to 0.05 MPa. The overall valve opening pressure of the valve structure 200 is the sum of the valve opening pressures of the check valves 210 and 220, which is 0.1 MPa in this example. The valve opening pressure is the pressure difference between the primary side pressure and the secondary side pressure.

Before or immediately after the valve structure 200 is attached to the container 110A, it is preferable to fill the intervalve space S3 with gas so that the pressure is higher than atmospheric pressure. In this case, the intervalve space S3 is kept at a higher pressure than atmospheric pressure immediately after the electric storage device 100 is manufactured, that is, before the check valve 210 is opened even once. Therefore, the intrusion of air from the external space into the intervalve space S3, and further into the internal space S1, is more effectively prevented. In addition, when the pressure on the primary side of the check valve 210 is made high and the check valves 210 and 220 are inspected for opening after the manufacture of the valve structure 200, the inspection can also serve as a process of filling the intervalve space S3 with gas. In addition, the gas filled into the intervalve space S3 is preferably an inert gas such as argon. When the intervalve space S3 is filled with gas by the check valves 210 and 220 opening inspection, the inert gas may be used to perform the opening inspection. In this case, even the slight amount of gas entering the internal space S1 can prevent the energy storage device element 120 from deteriorating.

The liquid 70 is arranged to contact the valve body 52 and the valve seat 53 of the check valve 210 in order to prevent the air from entering the internal space S1 (see FIG. 1). The specific arrangement of the liquid 70 can be selected arbitrarily as long as the liquid 70 contacts the valve body 52 and the valve seat 53. In this embodiment, the liquid 70 is filled to a predetermined range of the intervalve space S3. The liquid 70 may be filled, for example, before the check valve 210 and the check valve 220 are assembled, or may be filled from the inlet 20A after the check valve 210 and the check valve 220 are assembled. The liquid 70 may also be filled from the outlet 20B before the spring 51 and the valve body 52 of the check valve 220 are arranged. It is sufficient that the liquid 70 adheres to at least the portion of the surface of the valve body 52 that contacts the valve seat 53 and the portion of the surface of the valve seat 53 that contacts the valve body 52 when the check valve 210 is in the closed state. Such an arrangement of the liquid 70 can be formed, for example, by injecting air from the inlet 20A in the state shown in FIG. 10 to blow away the liquid 70.

According to this embodiment, when the check valve 50 is open, gas generated in the internal space S1 (see FIG. 1) flows out from the gap formed between the valve body 52 and the valve seat 53. The flowing gas passes through the liquid 70 in the form of bubbles, and after passing through the liquid 70, flows out toward the outlet 20B. On the other hand, if the atmosphere and the moisture contained therein enter the valve structure 200 through the outlet 20B, the liquid 70 prevents the moisture from entering the interior of the container 110A beyond the check valve 210. This prevents the atmosphere and the moisture contained therein from entering the container 110A.

3. Modifications
The above-described embodiments are examples of forms that the valve structure for an electricity storage device and the electricity storage device according to the present invention may take, 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. One example is a form in which part of the configuration of each embodiment is replaced, changed, or omitted, or a form in which a new configuration is added to each embodiment. Below, some examples of modified versions of each embodiment are shown. Note that the gist of the following modified versions can be applied to the second embodiment in addition to the first embodiment.

<3-1>
The configuration of the check valve 50 is not limited to those shown in the respective embodiments and can be changed as desired. For example, the check valve 50 can be configured as a check valve of another type capable of repeatedly releasing gas, such as a poppet type, a duckbill type, an umbrella type, or a diaphragm type, instead of the ball spring type described above.

<3-2>
In the second embodiment, a rupture valve capable of one-time gas release, that is, a rupture valve configured to burst when the internal pressure of container 110A increases due to gas generated inside container 110A, may be used instead of check valve 210 or check valve 220. In this modification, when taking into consideration the fact that liquid 70 is filled from inlet 20A, it is preferable to use a rupture valve instead of check valve 220.

<3-3>
In the second embodiment, as shown in Fig. 12, the liquid 70 may be arranged so as to be in contact with the valve body 52 and the valve seat 53 of the check valve 220. The specific arrangement of the liquid 70 can be selected arbitrarily as long as the liquid 70 is in contact with the valve body 52 and the valve seat 53 of the check valve 220. In this modification, the liquid 70 is filled in a predetermined range of the accommodation space S2. Also, in this modification, the liquid 70 arranged so as to be in contact with the valve body 52 and the valve seat 53 of the check valve 210 can be omitted.

<3-4>
10 and the modified example of the second embodiment shown in Fig. 12, the first lid material 91 may be disposed on the primary side of the check valve 220 and above the liquid level of the liquid 70 in contact with the valve body 52 and valve seat 53 of the check valve 210. According to this modified example, the check valve 220 is prevented from opening by the liquid 70 in contact with the valve body 52 and valve seat 53 of the check valve 210 and the organic solvent contained in the electricity storage device element 120 (see Fig. 2).

<3-5>
In the second embodiment, the valve structure 200 has two check valves 210 and 220, but may have three or more check valves arranged along the extension direction of the passage LA. These three or more check valves close the passage LA at different positions in the passage LA in the closed state.

<3-6>
The configuration of the valve body 52 is not limited to those shown in each embodiment, and can be changed arbitrarily. Figure 13 is a cross-sectional view of the valve structure 10 having a modified valve body 252. The valve body 252 is inverted T-shaped, and has a disk-shaped portion 252A and a cylindrical shaft portion 252B that is continuous with an end face 252AX on the front side in the front-rear direction of the disk-shaped portion 252A and extends forward from the center of the end face 252AX. Both the disk-shaped portion 252A and the shaft portion 252B extend with the central axis C1 as the central axis. The bottom surface 252AY, which is the end face on the rear side in the front-rear direction of the disk-shaped portion 252A, is received by the top surface 253A of the valve seat 253 and contacts the top surface 253A when the check valve 250 is in the closed state. The shaft portion 252B of the valve body 252 is inserted into the space inside the spring 51, thereby connecting the valve body 252 and the spring 51.

<3-7>
The configuration of the peripheral seal portion 150 is not limited to those shown in each embodiment, and can be changed arbitrarily. As shown in Fig. 14, the peripheral seal portion 150 may have inclined 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 inclined seal portions 251, 252 that incline to approach the 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 inclined seal portions 351, 352 that incline to approach the 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 inclined seal portions 451, 452 that incline to approach 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, so that the gas can be suitably discharged through the valve structure 10.

<3-8>
Although container 110A is formed by heat-sealing packaging material 111 and packaging material 112, container 110A may also be formed by folding a single sheet of packaging material and heat-sealing the peripheral portion.

<3-9>
The container 110A may be made of the packaging materials 111, 112 as described above, but may also be, for example, a metal can.

REFERENCE SIGNS LIST 10, 200: Valve structure for electricity storage device 20B: Outlet 50: Check valve 52, 252: Valve body 53: Valve seat 70: Liquid 80: Sealing member 90: Lid 100: Electricity storage device 110A: Container 120: Electricity storage device element LA: Passage

Claims (8)

a passageway that communicates between the inside and the outside of a container that houses the electricity storage device element;
a check valve that is disposed to close the passage and 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,
a liquid that is arranged to be in contact with the valve seat and the valve body to prevent air from entering the container; Under normal use conditions, the melting point of the liquid is 10° C. or lower.
The valve structure for an electricity storage device according to claim 1 . The valve structure for an electricity storage device according to claim 1 , wherein the liquid has a boiling point of 150° C. or higher under a normal usage environment. The valve structure for an electricity storage device according to any one of claims 1 to 3, wherein the liquid includes liquid paraffin. The valve structure for an electricity storage device according to any one of claims 1 to 4, wherein the liquid has a viscosity in the range of 0.1 mPa·s to 2000 mPa·s. the passage includes an outlet facing an exterior space;
The valve structure for an electricity storage device according to any one of claims 1 to 5, further comprising a seal member attached to close the outlet. The valve structure for an electricity storage device according to any one of claims 1 to 6, further comprising a cover material arranged on at least one of a primary side and a secondary side of the check valve and configured to allow the gas to pass therethrough. The valve structure for an electricity storage device according to any one of claims 1 to 7,
the container to which the valve structure for an electricity storage device is attached.