JP7735657B2 - 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 with a check valve is attached to the heat-sealed portion of the pouch along its periphery. This check valve is configured to activate 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 than other portions. The easy-peel portion peels when the internal pressure of the laminated container rises above a certain level, allowing gas to escape 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 breakable valve that does not return to its original state once peeled.

JP 2016-31934 A JP 2010-153841 A

A check valve is generally a one-way valve designed to prevent backflow. However, in batteries like those 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 done with greater precision. For this reason, it is practically difficult for a check valve like the one described in Patent Document 1, which vents gas from within a pouch, to completely prevent air from entering the pouch to the high level required for batteries. Therefore, batteries like those described in Patent Document 1 face the problem of moisture from the atmosphere entering the pouch, causing battery degradation.

On the other hand, in a battery like that described in Patent Document 2, once the break valve breaks, atmospheric air enters the laminated container through the passage formed by the break. Therefore, even when a break valve is used as in Patent Document 2, there is the problem that moisture contained in the atmosphere can enter the laminated container, causing battery degradation.

The present invention aims 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 that includes the valve structure.

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 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 includes a valve seat and a valve element that contacts the valve seat in a closed state, and the valve seat and valve element contact each other at multiple points in the closed state.

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 multiple steps, and the valve seat and the valve body contact each other via the multi-stage structure in the closed state.

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 has a shape that tapers toward the interior of the container, and the insertion portion has a shape that tapers toward the interior of the container so as to follow the shape of the insertion hole.

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 element when the check valve transitions from one of the closed state and the open state to the other.

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.

A 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, comprising a liquid arranged to be in contact with the valve seat and the valve body.

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.

The valve structure for an electricity storage device according to an eighth aspect of the present invention is the 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.

A ninth aspect of the present invention relates to a valve structure for an electricity storage device according to any one of the sixth to eighth aspects, in which the liquid includes liquid paraffin.

A valve structure for an electricity storage device according to a tenth aspect of the present invention is a 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.

An electricity storage device according to an eleventh aspect of the present invention comprises a 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.

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

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. FIG. 7 is a cross-sectional view taken along line D7-D7 in FIG. 4. FIG. 8 is a perspective view of the valve body of FIG. 7 as viewed from the bottom side. FIG. 9 is a front view of the valve body of FIG. 8 . FIG. 10 is a cross-sectional view of a valve structure for an electricity storage device according to a second embodiment. FIG. 11 is a perspective view of the valve seat of FIG. 10 as viewed from the top side. 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. 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. FIG. 10 is a plan view of an electricity storage device according to a modified example. FIG. 10 is a plan view of an electricity storage device according to another modified example. FIG. 10 is a plan view of an electricity storage device according to yet another modified example. FIG. 10 is a plan view of an electricity storage device according to yet another modified example. FIG. 10 is a cross-sectional view of a modified valve structure.

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 same, and a method for manufacturing the same, with reference to the drawings.

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 would not normally be 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 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, with a portion of the space between the one end and the other end fused to the peripheral seal portion 150 via the tab film 140.

The container 110 includes a container 110A. The container 110A is composed of 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 150. This peripheral seal 150 forms an internal space S1 of the container 110A that is isolated from the external space. The peripheral seal 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 150 refers to the portion where the packaging materials 111 and 112 are fused together to form a single unit. As shown in FIG. 2, the portion of the peripheral seal 150 that sandwiches the tab 130 and tab film 140 is made up of an integrated package of the packaging material 112, the tab 130, the pair of tab films 140, and the packaging material 111, while the portion of the peripheral seal 150 that sandwiches only the pair of tab films 140 is made up of an integrated package of the packaging material 112, the pair of tab films 140, and the packaging material 111.

Packaging materials 111, 112 are composed of, for example, a resin molded product or film. Resin molded products can be manufactured by methods such as injection molding, pressure forming, vacuum forming, and blow molding, and in-mold molding can also be used to add design and functionality. Resins can be polyolefin, polyester, nylon, ABS, and other materials. Films can be resin films manufactured by methods such as inflation and T-die methods, or films in which such resin films are laminated onto metal foil. Films can be stretched or unstretched, and can be single-layer or multilayer films. Multilayer films can be manufactured by a coating method, or can be made by bonding multiple films together with an adhesive, or can 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 laminate film. The laminate film can be a laminate formed by laminating a base layer, a barrier layer, and a heat-sealable resin layer. The base layer functions as the base material for 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 energy 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 container 110A is not particularly limited and can be, for example, a bag (pouch). 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, which corresponds to the outer periphery in a plan view, and a molded portion 111B, which is continuous with the inner edge of flange portion 111A and bulges downward from the flange portion. Similarly, packaging material 112 includes a rectangular annular flange portion 112A, which corresponds to the outer periphery in a plan view, and a molded portion 112B, which is continuous with the inner edge of flange portion 112A and bulges upward from the flange portion. 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 together to form 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 capacitor or other power storage component. When an abnormality occurs in the power storage device element 120, gas may be generated in the internal space S1 of the container 110A. If the power storage device 100 is a lithium-ion battery, the organic solvent serving as the electrolyte may volatilize, and the electrolytic solution may decompose, generating gases such as volatile organic solvents, carbon monoxide, carbon dioxide, methane, ethane, hydrogen, and hydrogen fluoride in the internal space S1 of the container 110A. If the power storage device 100 is a capacitor, gas may be generated in the internal space S1 of the container 110A due to chemical reactions in the capacitor. The power storage device 100 may also be an all-solid-state battery. In this case, the power storage device element 120 may include a solid electrolyte capable of generating gas. For example, if the solid electrolyte is sulfide-based, hydrogen sulfide gas may be generated.

The tabs 130 are metal terminals used for inputting and outputting power to and from the energy 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, with one forming a positive terminal and the other forming a negative terminal. One left and right end of each tab 130 is electrically connected to an electrode (positive or negative) of the energy 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 energy storage device 100 configuration is particularly preferable for use in electric vehicles, hybrid vehicles, and other electric vehicles that use multiple energy storage devices 100 connected in series at high voltage. The attachment positions of the two tabs 130 that form the positive and negative terminals are not particularly limited; for example, they may be arranged on the same side of the peripheral seal portion 150.

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

The tab film 140 is a so-called adhesive film that is configured to adhere to both the packaging materials 111, 112 and the tab 130 (metal). The tab film 140 allows the tab 130 and the innermost layer (thermally adhesive resin layer) of the packaging materials 111, 112 to be fixed together, even if they are made of different materials. The tab film 140 is first fused and fixed to the tab 130 to form an integrated unit. The tab 130 with the attached tab film 140 is then sandwiched between the packaging materials 111, 112 and fused to form an integrated unit, as shown in Figure 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, potentially damaging the power storage device 100. The housing 110 is equipped with a valve structure 10 as a mechanism to prevent this from happening. The valve structure 10 is a gas vent valve for regulating the pressure in the internal space S1, and is attached, for example, to 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. 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). FIG. 5 is a view of the valve structure 10 as viewed from the second body 40 side (from the front). FIG. 6 is a perspective view of the valve structure 10 as viewed from the first body 30 side (from the rear).

Figure 7 is a cross-sectional view taken along line D7-D7 in Figure 4. As shown in Figure 7, the check valve 50 is housed in the housing 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, allowing the gas to pass from the inside to the outside 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 Figure 1). A passage LA is formed within 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.

The check valve 50 is positioned so that, in the closed state, it blocks the passage LA. 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. When the container 110A is molded, the attachment portion 31 is heat-sealed together with the packaging materials 111, 112 via the heat-sealing film 11 (see FIG. 1). This heat sealing fuses and joins the outer peripheral surface 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).

The connecting portion 32 is positioned outside the peripheral seal portion 150 and is not sandwiched between the packaging materials 111, 112 (see Figures 1 and 2). Furthermore, the second body 40, which is positioned further outboard than the connecting portion 32, is also positioned 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 other factors 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. The mounting portion 31, the connecting portion 32, and the second body 40 share 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-LZ also extend coaxially around the central axis C1. In this embodiment, the inlet 20A and the outlet 20B are disposed on the front-to-rear end faces of the valve body 20 rather than on the outer peripheral surface. In particular, the central axis C1, which extends linearly in the front-to-rear direction, passes through the centers of the inlet 20A and the outlet 20B. Although not limited thereto, the cross sections of the air passages LX-LZ perpendicular to the central axis C1 are circular. The air passages LX-LZ are interconnected and collectively constitute a passage LA. The third air vent passage LZ is located closer to the exterior of the container 110A than the first air vent passage LX. The second air vent passage LY is located even closer to the exterior of the container 110A than the third air vent passage LZ.

As shown in Figures 4 and 6, the mounting portion 31 has a non-circular outer shape when viewed along the direction of extension of the central axis C1. More specifically, when viewed along the direction of extension of the central axis C1, the mounting portion 31 has a first wing-shaped portion 31A that becomes thinner as it moves leftward from the center in the left-right direction, and a second wing-shaped portion 31B that becomes thinner as it moves rightward. Therefore, in this embodiment, the mounting portion 31 becomes thicker as it moves closer to the center in the width direction (left-right direction) of the energy storage device 100, and becomes thinner as it moves closer to the ends in the width direction (left-right direction) of the energy storage device 100.

In this embodiment, the first wing-shaped portion 31A and the second wing-shaped portion 31B are formed, and therefore 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 energy storage device 100 in the vertical direction at the transition point between the portion of the peripheral seal 150 where the mounting portion 31 is not sandwiched and the portion of the peripheral seal 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 area surrounding the position where the mounting portion 31 is attached in the peripheral seal 150. This allows the mounting portion 31 to be firmly fixed to the peripheral seal 150 via the heat-sealing film 11.

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 a certain distance from the central axis C1 and a further plane cut out symmetrically to the plane 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 below). 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 below). Furthermore, 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 below). The outer peripheral 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 extension direction of the central axis C1, 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 described above can be formed by cutting the outer peripheral surface of a cylindrical member so as to form the first flat surface 32A and the second flat surface 32B.

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 with the check valve 50 accommodated in the accommodation space S2.

The first body 30 and the second body 40 are joined together by at least one of adhesive, threaded joints, and interlocking grooves. 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, as well as by an adhesive applied to the male threads 32X and the female threads 40A. The adhesive material is not particularly limited, but may be composed of an acid-modified polyolefin and an epoxy resin. This type of adhesive is superior to, for example, an adhesive made from a modified silicone resin in that it can suppress deterioration of adhesive performance due to the electrolyte solution contained in the container 110A. Any method can be used to join the first body 30 and the second body 40. Therefore, in this embodiment, at least one of the structure for interlocking the male threads 32X and the female threads 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, when viewed along the direction in which the central axis C1 extends, all have different shapes depending on the role assigned to each part.

The second body 40 holds the main structural components that enable the valve structure 10 to function as a gas vent valve. In this embodiment, the check valve 50 has a spring 60, valve seat 70, and valve element 80 as a valve mechanism housed within the second air passage LY inside the second body 40. The spring 60, valve element 80, and valve seat 70 are arranged in this order within the second air passage LY from the outlet 20B toward the inlet 20A. In this embodiment, as shown in Figures 7 and 8, the first body 30 and valve seat 70 are configured as separate parts, but they may also be configured as an integrated unit.

The valve seat 70 receives the valve element 80, which 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 could also be, for example, a leaf spring.

In this embodiment, the valve seat 70 has a shape similar to a cylinder extending about the 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 the 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 tapers toward the inlet 20A.

The valve element 80 has a cylindrical base 81, a conical insertion portion 82 extending from the lower surface 81A of the base 81 toward the valve seat 70, and a cylindrical shaft portion 83 extending from the upper surface 81B of the base 81 toward the outlet 20B. The base 81, insertion portion 82, and shaft portion 83 extend about a central axis C1. When the check valve 50 is in the 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 the open state to the closed state, the insertion hole 71 guides the valve element 80 to a specified position. As a result, the position of the valve element 80 relative to the valve seat 70 is unlikely to shift when the check valve 50 is closed. In other words, the position of the valve element 80 relative to the central axis C1 is unlikely to shift. 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. This connects the valve element 80 and the spring 60.

In this embodiment, the valve seat 70 and the valve element 80 are configured to contact each other at multiple locations so that they come into firmer contact when the check valve 50 is in a 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 via the multi-stage structure 90 when the check valve 50 is in a closed state. In this embodiment, the multi-stage structure 90 is formed in the valve element 80.

As shown in Figures 8 and 9, the insertion portion 82 of the valve body 80 has a multi-stage structure 90 including multiple protrusions 91 and multiple recesses 92. Such a multi-stage structure 90 can be achieved, for example, by forming recesses 92 in the insertion portion 82. The protrusions 91 and recesses 92 are alternately arranged in the direction in which the central axis C1 extends. The protrusions 91 and recesses 92 are formed over the entire circumferential direction of the insertion portion 82. The number of protrusions 91 in the multi-stage structure 90 can be selected as desired, as long as it is two or greater. In this embodiment, the multi-stage structure 90 has six protrusions 91. The number of recesses 92 in the multi-stage structure 90 is determined, for example, based on the number of protrusions 91. In this embodiment, the multi-stage structure 90 has six recesses 92.

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, for the same biasing force of the spring 60, the valve seat 70 and the valve element 80 in this embodiment contact each other with greater pressure than when the valve seat 70 and the valve element 80 make surface contact at a single location. Therefore, when the check valve 50 is in the closed state, if atmospheric air and the moisture contained therein enter the valve structure 10 through the outlet 20B, the check valve 50 prevents the moisture from penetrating beyond the check valve 50 and into the container 110A. This prevents atmospheric air and the moisture contained therein from entering the container 110A.

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 and open states to the other. There is essentially 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. Therefore, when the check valve 50 transitions from one of the closed and open states 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.

Because the inner surface 42A of the side wall 42 and the surface of the base 81 of the valve body 80 are in contact with each other, when the check valve 50 is in the open state, it is difficult for much gas to pass between the side wall 42 and the valve body 80. For this reason, in this embodiment, in addition to the outlet 20B, a discharge hole 42B is formed in the side wall 42 to allow smooth discharge of gas when the check valve 50 is in the 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 the 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 of the discharge hole 42B 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.

The valve seat 70 and the first body 30 can be bonded together, for example, with an adhesive. There are no particular limitations on the material of the adhesive; however, 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, to prevent 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 face 41 of the second body 40 and the front end face 32E of the connecting portion 32.

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 ventilation passage LX. That is, the first ventilation 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 primary space of the check valve 50, reaches a predetermined pressure, gas flows out of the internal space S1 and passes through the first ventilation passage LX and the third ventilation 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, moving the valve element 80 toward the outlet 20B, thereby opening the check valve 50. In this open state, gas generated in the internal space S1 flows through the 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. In this way, when the gas in the internal space S1 is discharged through the passage LA, the pressure in the internal space S1 pressing the valve body 80 toward the outlet 20B weakens, and the force of the spring 60 urging the valve body 80 toward the inlet 20A increases. As a result, the shape of the spring 60 is restored, and the check valve 50 is once again closed.

When the check valve 50 is closed, it can prevent atmospheric air 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 maintained at a relatively high pressure equal to or greater 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, effectively prevents atmospheric air from entering the internal space S1 and prevents deterioration of the electricity storage device element 120 due to moisture and other substances 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.

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, second body 40, and 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. If 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.

The heat-sealing film 11 shown in FIG. 1 and elsewhere is configured to adhere to both the valve structure 10 and the packaging materials 111, 112 of the container 110A by heat sealing. The heat-sealing film 11 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 housed in the housing space S2 (see FIG. 7). The heat-sealing film 11 is fused to the mounting portion 31 so as to cover most of the surface of the mounting portion 31. Various known adhesive films can be used as the heat-sealing film 11. For example, the heat-sealing film 11 may be a single-layer film of maleic anhydride-modified polypropylene (PPa), or a multi-layer laminate film of PPa, polyethylene naphthalate (PEN), and PPa. A multi-layer laminate film of PPa, polypropylene (PP), and PPa may also be used. Instead of the PPa resin, resins capable of bonding to metals, such as ionomer resin, modified polyethylene, and EVA, can also be used. In this embodiment, the heat-sealable film 11 is a three-layer laminate film containing a core material made 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.

In addition, particularly from the standpoint of electrolyte resistance, 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. 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, 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. In addition, particularly from the standpoint of electrolyte resistance, similar coatings may be applied to the surfaces of the connecting portion 32, the second body 40, and the check valve 50 in addition to 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, second body 40, and check valve 50, it is preferable to form a corrosion inhibitor coating layer in a predetermined area, 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 area where the second body 40 contacts the valve seat 70. However, from the perspective 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 particularly effective to apply such a coating to the mounting portion 31. The corrosion inhibitor material is not particularly limited, but an acid-resistant material is preferable, and the corrosion inhibitor coating layer can be formed by chromate chromate treatment, chromate phosphate treatment, or the like.

[2. Second embodiment]
The second embodiment differs from the first embodiment in the configuration of the valve structure 10. 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, with the focus being on the differences from the first embodiment.

Figure 10 is a cross-sectional view of the 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 generally smooth.

As shown in Figures 10 and 11, the insertion hole 71 of the valve seat 70 has a multi-stage structure 290 including multiple protrusions 291 and multiple recesses 292. Such a multi-stage structure 290 can be achieved, for example, by forming recesses 292 in the insertion hole 71. The protrusions 291 and recesses 292 are alternately arranged in the direction in which the central axis C1 extends. The protrusions 291 and recesses 292 are formed all around the insertion hole 71 in the circumferential direction. The number of protrusions 291 in the multi-stage structure 290 can be selected as desired, as long as it is two or greater. In this embodiment, the multi-stage structure 290 has six protrusions 291. The number of recesses 292 in the multi-stage structure 290 is determined, for example, based on the number of protrusions 291. In this embodiment, the multi-stage structure 290 has six recesses 292.

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, for the same biasing force of the spring 60, the valve seat 70 and the valve element 80 in this embodiment contact each other with greater pressure than when the valve seat 70 and the valve element 80 are in surface contact at a single location. Therefore, when the check valve 50 is in the closed state, if atmospheric air and the moisture contained therein enter the valve structure 10 through the outlet 20B, the check valve 50 prevents the moisture from penetrating beyond the check valve 50 and into the container 110A. This prevents atmospheric air and the moisture contained therein from entering the container 110A.

3. Modified Examples
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.

<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.

Figure 12 is a cross-sectional view showing a modified valve seat 370 and valve body 380. The valve seat 370 of this modified example is cylindrical. A multi-stage structure 390 is formed on the upper surface 371 of the valve seat 370. The multi-stage structure 390 has multiple convex portions 391 and multiple concave portions 392. The valve body 380 has a cylindrical base 381 and a cylindrical shaft portion 382 extending from the upper surface 381A of the base 381 toward the side opposite the valve seat 370. The lower surface 381B of the base 381 is generally smooth. When the check valve 50 is in the closed state, the lower surface 381B of the base 381 contacts the multiple convex portions 391. Note that a 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.

Figure 13 is a cross-sectional view showing a valve seat 470 and 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 the 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 the upper surface 481A of the base 481 toward the side opposite the valve seat 470. Of the surfaces of the base 481, at least the side surface 481C is a smooth surface. In this embodiment, the entire surface of the base 481 is a smooth surface. When the check valve 50 is in a closed state, the lower surface 481B of the base 481 contacts the bottom surface 471B of the insertion hole 471, and the side surface 481C contacts the multiple protrusions 491. Note that a multi-step structure may be formed on the side surface 481C of the base 481. In this case, the side surface 471A of the insertion hole 471 is a smooth surface.

<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.

<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.

<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, so that the gas can be suitably discharged via the valve structure 10.

<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 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 oils such as silicone oil, or ionic liquids, etc., can also be used as the liquid 500. In a preferred example, the liquid 500 preferably has the property of remaining in liquid form 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.

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 allowing gas to pass through easily and the viewpoint of 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, gas can pass through easily. 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, it can be handled easily. 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 for the viscosity of liquid 500 is 0.1 mPa·s to 2000 mPas. An example of a more preferred range for the viscosity of liquid 500 is 0.5 mPa·s to 500 mPas. An example of an even more preferred range for the viscosity of liquid 500 is 1.0 mPa·s to 100 mPas. Note that the viscosity of liquid 500 is measured in the temperature range of 10°C to 40°C. Furthermore, if liquid 500 is crude oil or petroleum, the viscosity of 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. If liquid 500 is other than crude oil or petroleum, the viscosity of liquid 500 is measured in accordance with "JIS Z8803 Method for measuring viscosity of liquids."

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 Figure 18, when the check valve 50 is in the closed state, the liquid 70 is arranged so as to adhere to at least the portion of the surface of the valve element 80 that contacts the valve seat 70 and the portion of the surface of the valve seat 70 that contacts the valve element 80. In another example, the liquid 500 is filled within a predetermined range of the storage space S2.

<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 periphery.

<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.

10, 200: Valve structure for electricity 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 part 100: Electricity storage device 110A: Container 120: Electricity storage device element 90, 290: Multi-stage structure LA: Passage

Claims (10)

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. 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,
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. 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,
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. The valve structure for an electricity storage device according to claim 3 , 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. 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,
a liquid disposed in contact with the valve seat and the valve body;
Valve structure for power storage device. The melting point of the liquid is 10°C or less.
The valve structure for an electricity storage device according to claim 5 . The valve structure for an electricity storage device according to claim 5 or 6 , wherein the liquid has a boiling point of 150°C or higher. The valve structure for an electricity storage device according to any one of claims 5 to 7 , wherein the liquid includes liquid paraffin. The valve structure for an electricity storage device according to any one of claims 5 to 8 , wherein 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 1 to 9 ,
the container to which the valve structure for an electricity storage device is attached.