Closed container including an activatable vent

Abstract

There is provided a closed container comprising a housing wall defining an aperture, a membrane, and a barrier, the closed container configured to move between a first configuration where the barrier prevents passage of fluid along the pathway to the exterior of the closed container and a second configuration where the barrier does not prevent passage of fluid along the pathway to the exterior of the closed container and the membrane remains in the pathway, wherein the closed container is configured to transition from the first configuration to the second configuration when a threshold is exceeded.

Description

[0001] Closed Container Including an Activatable Vent

[0002] Field

[0003] The present disclosure is directed to closed containers including a vent, specifically to closed containers such as batteries including an activatable vent.

[0004] Background

[0005] Closed containers are used widely to retain fluids in a controlled environment. These containers are often sealed from the exterior of the closed container to ensure that the fluid retained within the closed container is not contaminated from exterior particulates, or fluids, which may interact negatively with the retained fluid by chemical reaction or otherwise.

[0006] However, some liquids retained within the closed container may produce a gas through decomposition reactions over time or otherwise. As gas is produced, the pressure within the closed container increases and if it is allowed to increase beyond a certain threshold for a given closed container, could cause the closed container to fail or burst.

[0007] Accordingly, in some closed containers vents are provided to allow excess gases to escape the closed container to attempt to prevent failure of the closed container. These vents are also often required to prevent the ingress of at least some gases and liquids, such as water vapor or liquid water, for example. Therefore, the selection of materials for use in such vents has to be carefully tailored for a given application and often inherently limits the rate of gas flow through the vent in order to retain the necessary selectivity.

[0008] For example, lithium-ion batteries are often provided in a housing such as a prismatic can or a pouch that retain an electrolyte and that must be isolated from oxygen and water in order to retain the integrity of the electrolyte and electrodes. However, during normal operation of a lithium ion battery, gases may be produced through either electrolyte decomposition or other unwanted side reactions that may occur during operation of the battery.

[0009] If the rate of gas production is greater than the ability of the vent to allow to escape, or if the battery does not have a vent, the battery can swell, and, if this is allowed to continue, can fail or cause malfunctions of the device within which the battery is installed.

[0010] Accordingly, there remains a need for improved vent assemblies for use in closed containers. Summary

[0011] According to a first aspect there is provided a closed container comprising a housing wall defining an aperture, a membrane, and a barrier, a pathway is defined by the housing wall between the interior of the closed container and the exterior of the closed container through the aperture, the membrane and the barrier being positioned within the pathway such that membrane and the barrier substantially occlude the pathway, the closed container configured to move between a first configuration where the barrier prevents passage of fluid along the pathway to the exterior of the closed container and a second configuration where the barrier does not prevent passage of fluid along the pathway to the exterior of the closed container and the membrane remains in the pathway, wherein the closed container is configured to transition from the first configuration to the second configuration when a threshold is exceeded.

[0012] As used herein, the term “barrier” refers to a feature that substantially blocks or prevents passage of fluid past or through it in the closed container. Typically, the barrier substantially blocks or prevents passage of fluid past or through it in the closed container in the first configuration and does not substantially block or prevent passage of fluid past or through it in the closed container in the second configuration.

[0013] The provision of a barrier that may be changed from occluding the pathway in the first configuration to not occluding the pathway in the second configuration and a membrane that remains within the pathway in the first configuration and the second configuration can be considered to be an “activatable vent” for the closed container. During normal use the closed container is sealed by the activatable vent from the environment exterior to the closed container. In this first configuration the interior of the closed container is protected from exterior contaminants such as particulates, liquids such as water and gasses such as water vapour and oxygen. However, when the threshold is exceeded the activatable vent is activated by the barrier changing to no longer occlude the pathway in the second configuration, thereby allowing gas within the closed container to escape from within the closed container to the exterior. Accordingly, the gas transmission rate along the pathway may be increased when the closed container transitions from the first configuration to the second configuration.

[0014] Typically, the closed container retains a fluid. The fluid may be a liquid. The fluid may be a gas.

[0015] The closed container may be a battery. The closed container may be a chemical container.

[0016] The closed container may be food container. The housing wall may be a flexible housing wall. The flexible housing wall may comprise a polymer material. The flexible housing wall may comprise polypropylene (PP), polyamide (PA) including nylon, or polybutylene terephthalate (PBT), polyethylene (PE), or polyethylene terephthalate (PET). The housing wall may comprise a metallic material. The housing wall may comprise aluminium. The housing wall may comprise aluminium foil, for example.

[0017] The housing wall may comprise a laminate material. The laminate material may comprise at least one polymer layer. The laminate material may comprise at least one metallic layer. The laminate material may comprise at least one polymer layer and at least one metallic layer. The laminate material may comprise a first polymer layer, a metallic layer and a second polymer layer. The metallic layer may be located between the first polymer layer and the second polymer layer.

[0018] The closed container may be a pouch.

[0019] In embodiments where the closed container is a battery, the battery may comprise a pouch cell. The battery may comprise a prismatic or cylindrical can. The closed container may be configured to retain battery fluid that allows the transfer of ions from a first electrode to a second electrode through the battery fluid or electrolyte. Accordingly, the closed container may retain at least two electrodes and at least two electrical contacts that are configured to connect the at least two electrodes to an external electrical circuit. The housing wall may be configured to be substantially impervious to the fluid that is retained within the closed container. For example, the battery pouch may be a lithium (Li) ion pouch cell.

[0020] The housing wall may be a rigid housing wall. The rigid housing wall may comprise a rigid polymer material. The rigid housing wall may comprise a thermoplastic material. The rigid housing wall may comprise a reinforced thermoplastic material. For example, the rigid housing wall may comprise a thermoplastic material such as polypropylene (PP), polyethylene (PE), polybutylene terephthalate (PBT), or polyethylene terephthalate (PET) reinforced with a fiber such as glass fiber or similar. The rigid housing may comprise a rigid metallic material. The rigid housing wall may comprise aluminium, steel, stainless steel, copper, brass, bronze, tin or lead, for example.

[0021] The threshold may be a pressure threshold. When the pressure threshold is exceeded the housing wall may flex or bend such that the barrier no longer occludes the pathway to thereby allow gas to flow along the pathway through the membrane and aperture to the exterior of the closed container.

[0022] The closed container may be configured to transition from the first configuration to the second configuration when the pressure within the closed container is greater than the pressure threshold.

[0023] The pressure threshold may be dependent on the material of the housing wall of the closed container. For example, the pressure threshold may be a higher pressure for a housing wall comprising a rigid material than the pressure threshold for a housing wall comprising a flexible material. In embodiments where the closed container is a battery, the pressure threshold may be a higher pressure for a battery comprising a prismatic or cylindrical can than the pressure threshold for a battery comprising a pouch cell, for example.

[0024] The pressure threshold may be at least 0.01 bar. The pressure threshold may be at least 0.05 bar. The pressure threshold may be at least 0.1 bar. The pressure threshold may be at least 0.2 bar. The pressure threshold may be at least 0.3 bar. The pressure threshold may be at least 0.4 bar. The pressure threshold may be at least 0.5 bar.

[0025] The pressure threshold may be from 0.01 to 6 bar. The pressure threshold may be from 0.01 to 5 bar. The pressure threshold may be from 0.01 to 4 bar. The pressure threshold may be from 0.01 to 3 bar. The pressure threshold may be from 0.01 to 2 bar. The pressure threshold may be from 0.01 to 1.5 bar. The pressure threshold may be from 0.01 to 1 bar. The pressure threshold may be from 0.01 to 0.5 bar. The pressure threshold may be from 0.01 to 0.1 bar. The pressure threshold may be from 0.05 to 6 bar. The pressure threshold may be from 0.1 to 6 bar. The pressure threshold may be from 0.2 to 6 bar. The pressure threshold may be from 0.3 to 6 bar. The pressure threshold may be from 0.4 to 6 bar. The pressure threshold may be from 0.5 to 6 bar.

[0026] In some embodiments, the barrier may be more rigid than the housing wall. For example, in embodiments where the housing wall is flexible, the barrier may be less flexible than the housing wall. The barrier may be significantly less flexible than the housing wall. The barrier may be substantially rigid.

[0027] The barrier may substantially not flex or bend when the closed container moves from the first configuration to the second configuration. The barrier may be substantially planar.

[0028] The barrier may have an irregular shape. The barrier may be substantially planar and have an irregular shape. The barrier may have an elongate shape. The barrier may be substantially planar and have an elongate shape.

[0029] The barrier may optionally have a teardrop shape or a guitar pick shape. The shape of the barrier may be configured to increase the force applied to at least one end of the barrier when a container wall flexes during use. For example, in embodiments where the threshold is a pressure threshold, the shape of the barrier may be configured to increase the force applied to at least one end of the barrier when the pressure within the closed container increases.

[0030] The barrier may comprise at least one polymer layer. The barrier may comprise at least two polymer layers. The at least two polymer layer may comprise a different polymer. The at least two polymer layers may comprise the same polymer.

[0031] The barrier may comprise at least one metallic layer. The at least one metallic layer may be provided on a side of the barrier facing the exterior of the closed container. The at least one metallic layer may be provided on a side of the barrier facing the aperture defined in the housing wall.

[0032] The barrier may comprise at least one polymer layer and at least one metallic layer. The barrier may comprise at least two polymer layers and at least one metallic layer.

[0033] The at least one polymer layer may comprise polypropylene, polyethylene terephthalate (PET), polyamide, polyethylene, fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), polytetrafluoroethylene (PTFE), or co-polymers of tetrafluoroethylene (TFE).

[0034] The at least one polymer layer may comprise polypropylene.

[0035] The at least one metallic layer may comprise aluminium, steel or stainless steel.

[0036] In embodiments where the closed container is a battery, the threshold may be an electrical measurement from the battery such as voltage, current, or resistance. In some embodiments, the barrier, the membrane and a first portion of the housing wall may define a first enclosed volume. The barrier and a second portion of the housing wall may define a second enclosed volume. The first enclosed volume and the second enclosed volume may be separated from one another by the barrier. In the first configuration the barrier may seal the first enclosed volume from the second enclosed volume. The aperture defined by the housing wall may be defined in the first portion of the housing wall. In the first configuration the barrier may prevent the flow of fluid retained within the second enclosed volume entering the first enclosed volume. In the second configuration fluid may be free to flow between the second enclosed volume and the first enclosed volume. Accordingly, in the second configuration gas generated or retained within the second enclosed volume may flow along the pathway into the first enclosed volume to contact the membrane and pass through the membrane and the aperture to the exterior of the closed container.

[0037] The aperture may be defined within a portion of the housing wall. The membrane may span the aperture in both the first configuration and the second configuration. The membrane may be fixed to the portion of the housing wall around the aperture. Accordingly, the membrane may be positioned between the aperture and the barrier.

[0038] The housing wall may comprise a plurality of housing wall portions. The aperture may be defined between adjacent housing wall portions. Adjacent housing wall portions may be sealed together in a seam and the aperture may be formed in the seam. In embodiments where the closed container is a battery pouch cell, a seam typically corresponds to a heat sealed seam that closes the battery pouch, such as side seals and terrace seals for example.

[0039] In some embodiments the barrier may be positioned within the seam. The barrier may be positioned within the aperture adjacent to or at the external edge of the seam. The barrier may occlude or substantially occlude the aperture when the closed container is in the first configuration. The barrier may seal the aperture in the first configuration. The aperture may be opened when the closed container is in the second configuration.

[0040] The barrier may be fixed to opposing portions of the housing wall to thereby span the closed container. The barrier may be adhered to the opposing portions of the housing wall. The barrier may be welded to the opposing portions of the housing wall. The barrier may be a barrier element that it fixed to, adhered to or welded to the opposing portion of the housing wall. The barrier may be a weld between the opposing portions of the housing wall. In some embodiments the barrier may not be a weld. Typically, the barrier fails to no longer substantially occlude the pathway when the threshold is exceeded and the closed container moves from the first configuration to the second configuration.

[0041] The barrier may be configured to break when the threshold is exceeded. The barrier may break into a first barrier portion and a second barrier portion when the threshold is exceeded. A barrier space may be formed between the first barrier portion and the second barrier portion when the threshold is exceeded. Movement of the opposing portions of the housing wall to which the barrier is fixed away from each other may apply a force to the barrier such that the barrier fails when that force is sufficient to break the barrier into a first barrier portion and a second barrier portion. Pressure applied to the barrier may be sufficient to cause the barrier to break. The first barrier portion may remain fixed to a first portion of the opposing portions of the housing wall. The second barrier portion may remain fixed to a second portion of the opposing portions of the housing wall. The first barrier portion and the second barrier portion may be moved away from each other when the threshold is exceeded. Fluid may be able to flow along the pathway between the first barrier portion and the second barrier portion.

[0042] The barrier may comprise a fault element that is configured to break when the threshold is exceeded. The fault element may be positioned between the first barrier portion and the second barrier portion such that when the barrier breaks at the fault element, the first barrier portion and the second barrier portion are separated at the fault element.

[0043] The fault element may be a formation within the barrier portion that is weaker than the rest of the barrier. The fault element may be a portion of the barrier that is thinner than the rest of the barrier. The fault element may be a scored line on the barrier that is configured to be the weak point of the barrier. The fault element may be a portion of the barrier that has a lower tensile or z-strength than the rest of the barrier.

[0044] The barrier may at least partially detach from one of the opposing portions of the housing wall when the threshold is exceeded. The barrier may detach from one of the opposing portions of the housing wall when the threshold is exceeded. Movement of the opposing portions of the housing wall to which the barrier is fixed away from each other may apply a force to the barrier such that the barrier fails when that force is sufficient to detach the barrier from one of the opposing portions of the housing wall. Pressure applied to the barrier may be sufficient to cause the barrier to detach. A passage may be formed between the one of the two opposing portions of the housing wall and the barrier when the threshold is exceeded. Fluid may be able to flow along the passage between the one of the opposing portions of the housing wall and the barrier.

[0045] In embodiments where the barrier is adhered to opposing portions of the housing wall the bond between the barrier and one of the opposing portions of the housing wall may break when the threshold is exceeded to thereby detach the barrier from the housing wall such that the barrier fails.

[0046] In embodiments where the barrier is laminated to opposing portions of the housing wall the barrier may delaminate from one of the portions of the opposing portions of the housing wall when the threshold is exceeded to thereby detach the barrier from the housing wall such that the barrier fails.

[0047] The barrier may comprise a gas impermeable material. Accordingly, the barrier may prevent or substantially prevent the flow of gas. The barrier may comprise a liquid impermeable material. Accordingly the barrier may prevent or substantially prevent the flow of liquid. The barrier may comprise a material that is both gas impermeable and liquid impermeable and may prevent or substantially prevent the flow of fluid.

[0048] The barrier may comprise a gas permeable material and may have a thickness and / or length that presents a diffusion pathway for gas through the thickness of the barrier that is sufficient to substantially prevent the passage of gas through the barrier. Accordingly, the diffusion pathway may be sufficiently long and narrow to effectively prevent the passage of gas through the barrier. The diffusion pathway for gas through the thickness of the barrier may be at least 0.5 mm. The diffusion pathway for gas through the thickness of the barrier may be at least 1 mm. The diffusion pathway for gas through the thickness of the barrier may be at least 1.5 mm. The diffusion pathway for gas through the thickness of the barrier may be at least 2 mm.

[0049] The material of the barrier and the thickness of the barrier may be chosen to ensure that the flow of gas through the thickness of the barrier is substantially prevented by the barrier before the threshold is exceeded. For example, the thickness of the barrier may be greater for a barrier comprising a gas permeable material than for a barrier comprising a substantially gas impermeable material to ensure that the diffusion pathway through the barrier of the gas permeable material is sufficient to substantially prevent the flow of gas. The barrier may comprise a material selected from the group: an adhesive, a laminate, a sealant, a material with low tensile strength, a material with low z-strength, or a degradable material.

[0050] In embodiments where the barrier comprises a laminate, the laminate may comprise at least one binding layer and at least one break layer. The at least one binding layer may comprise a material configured to form a strong bond between the barrier and the inner surface of the housing wall. The at least one break layer may be configured to form a weak bond between the barrier and inner surface of the housing wall. The weak bond may be configured to break when the threshold is exceeded. The laminate may comprise at least a first binding layer, a second binding layer and at least one break layer. The at least one break layer may be positioned between the first binding layer and the second binding layer. The at least one break layer may be configured to form a weak bond between the first binding layer and the second binding layer. The weak bond between the first binding layer or the second binding layer and the at least one break layer may be configured to break when the threshold is exceeded.

[0051] The barrier may comprise a material selected from the group: thermoset adhesive, acrylic based adhesive, epoxy, urethane-based adhesive, rubber adhesive, silicone-based adhesive, metal foils including aluminium foil, laminated metal foils, fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), PTFE and co-polymers of tetrafluoroethylene (TFE), polyethylene (PE), polypropylene (PP), polybutene-1 , polyolefin blends, or combinations or co-polymers thereof.

[0052] The barrier may comprise a material selected from the group: FEP, PE, PP, polybutene-1 , polyolefin blends, combinations and co-polymers thereof.

[0053] The barrier may have a thickness of less than 250 pm. The barrier may have a thickness of less than 200 pm. The barrier may have a thickness of less than 150 pm. The barrier may have a thickness of less than 100 pm. The barrier may have a thickness of less than 90 pm. The barrier may have a thickness of less than 80 pm. The barrier may have a thickness of less than 70 pm. The barrier may have a thickness of less than 60 pm. The barrier may have a thickness of less than 50 pm. The barrier may have a thickness of less than 40 pm.

[0054] The barrier may have a thickness of from 5 to 250 pm. The barrier may have a thickness of from 10 to 250 pm. The barrier may have a thickness of from 20 to 250 pm. The barrier may have a thickness of from 30 to 250 pm. The barrier may have a thickness of from 40 to 250 pm. The barrier may have a thickness of from 5 to 200 pm. The barrier may have a thickness of from 5 to 150 pm. The barrier may have a thickness of from 5 to 100 pm. The barrier may have a thickness of from 5 to 90 pm. The barrier may have a thickness of from 5 to 80 pm. The barrier may have a thickness of from 5 to 70 pm. The barrier may have a thickness of from 5 to 60 pm. The barrier may have a thickness of from 5 to 50 pm. The barrier may have a thickness of from 5 to 40 pm.

[0055] The membrane is typically configured to not fail when the threshold is exceeded and the closed container moves from the first configuration to the second configuration. Accordingly, the membrane occludes the pathway in the first configuration and the second configuration such that fluid is blocked in the first configuration and gas may pass through the membrane in the second configuration to the aperture.

[0056] The membrane may be connected to opposing portions of the housing wall. The membrane may be in a closed configuration when the closed container is in the first configuration. The membrane may be in an open configuration when the closed container is in the second configuration. The membrane may remain connected to opposing portions of the housing wall in both the closed configuration and the open configuration.

[0057] The membrane may be sealed against the housing wall around at least the periphery of the membrane.

[0058] The membrane may comprise a non-porous material. The membrane may comprise a non- porous material that is configured to allow gas transfer through the membrane via a solution diffusion mechanism, for example.

[0059] The membrane may comprise a porous material. The membrane may be sufficiently porous to allow the flow of gas through the membrane. Accordingly, the membrane may be configured to allow gas flow through the membrane.

[0060] The membrane may be configured to allow the flow of gas through the membrane. The membrane may be configured to allow diffusion of gas through the membrane. The membrane may comprise pores that allow gas to diffuse through the membrane. The pores may be sized such that they allow gas to diffuse through the membrane but are sufficiently small to prevent a flow of gas through the membrane. The membrane may be structured such that the gas must take an indirect route through the membrane. The membrane may be impermeable to liquid. The membrane may be substantially impermeable to liquid. Accordingly, the membrane may allow the passage of gas through the membrane and not allow the passage of liquid through the membrane.

[0061] The membrane may comprise a fluoropolymer. The fluoropolymer may comprise a fluoropolymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), or co-polymers or combinations thereof.

[0062] The fluoropolymer may comprise a fluoropolymer selected from the group: PTFE, PFA and FEP.

[0063] The membrane may comprise a non-fluoropolymer. The non-fluoropolymer may comprise a non-fluoropolymer selected from the group: polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and poly(tetramethyl-p-silphenylenesiloxane) (PTMPS) or co-polymers or combinations thereof.

[0064] The membrane may comprise a polymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and poly(tetramethyl-p- silphenylenesiloxane) (PTMPS) or co-polymers or combinations thereof.

[0065] The membrane may comprise an expanded polymer. The expanded polymer may be selected from the group consisting of expanded PE (ePE), expanded PP (ePP), expanded PET (ePET), or an expanded fluoropolymer such as expanded PTFE (ePTFE) or expanded FEP (eFEP).

[0066] An expanded polymer may have an increased porosity when compared to the corresponding non-expanded polymer.

[0067] The membrane may comprise a dense polymer. The dense polymer may be selected from the group consisting of dense PE, dense PP, dense PET, or dense fluoropolymer such as dense PTFE, dense PCTFE, dense ETFE, dense PFA or dense FEP. As used herein, the term “dense polymer” refers to a polymer material that is substantially non-porous. Accordingly, the dense polymer may have a non-measurable airflow using the test method described herein.

[0068] The membrane may comprise a densified expanded polymer. The densified expanded polymer may be selected from the group consisting of densified ePE, densified ePP, densified ePET, or densified expanded fluoropolymer such as densified ePTFE or densified eFEP.

[0069] The term “densified expanded polymer” as used herein refers to an expanded polymer that has been densified after the material has been expanded.

[0070] A densified expanded polymer may have the microstructure of an expanded polymer and a lower porosity than the expanded polymer. For example, the densified expanded polymer may have the node and fibril structure of the expanded polymer but have a reduced porosity.

[0071] In some embodiments the membrane may comprise a laminate. The laminate may comprise an open layer. The open layer may comprise an expanded material. The open layer may comprise a porous material. The laminate may comprise a plurality of open layers. The laminate may comprise a dense layer. The dense layer may comprise a non-porous material. The laminate may comprise a plurality of dense layers.

[0072] The laminate may comprise an open layer and a dense layer. The open layer may be more porous than the dense layer. Accordingly, the gas permeability of the membrane may be determined by the dense layer.

[0073] The open layer may be configured to fix the membrane to opposed portions of the housing wall of the closed container. The membrane may be in a bent or folded configuration such that the open layer may be positioned against opposed portions of the housing wall of the closed container to thereby allow the open layer to fixed to the opposed portions of the housing wall. The open layer may be configured to fix the membrane to opposed sides of an aperture defined within the housing wall of the closed container.

[0074] A dense layer may fix the membrane to opposed interior surfaces of a housing wall of the closed container. The dense layer may fix the membrane to opposed sides of the aperture within the housing wall of the closed container. Typically, the membrane has a rate at which gas may flow through the membrane. In some embodiments, the rate at which gas is generated within the closed container may exceed the rate at which gas may flow through the membrane. The closed container may be configured to transition to a third configuration where the membrane fails such that there is no obstruction in the pathway. Accordingly, rapid pressure equalisation may occur when the closed container transitions to the third configuration. The closed container may be configured to transition from the second configuration to the third configuration when a second threshold is exceeded. Accordingly, the closed container may be configured to transition from the first configuration to the second configuration when a first threshold is exceeded and the closed container may be configured to transition from the second configuration to the third configuration when the second threshold is exceeded.

[0075] Typically, the second threshold is greater than the first threshold.

[0076] The second threshold may be a second pressure threshold. When the second pressure threshold is exceeded the housing wall may flex or bend such that the membrane fails to thereby allow gas to flow along the pathway of the vent assembly and aperture to the exterior of the closed container. Alternatively, when the second pressure threshold is exceeded, the membrane may fail without bending or flexing of the housing wall. Typically, the second pressure threshold is a greater pressure than the pressure threshold.

[0077] In a second aspect there is provided a closed container comprising a housing wall, a membrane and a barrier, the housing wall comprising two opposed edges, the two opposed edges abutting one another to form a seam, the membrane being provided on a first side of the seam and the barrier being provided on a second side of the seam, the seam and barrier preventing passage of fluid into or out of the closed container in a first configuration, the barrier being configured to break and a space to be formed between the two opposed edges of the housing wall in a second configuration when the pressure within the closed container exceeds a threshold pressure and a pathway is formed from within the closed container, through the membrane and the space between the two opposed edges of the housing wall to the exterior of the closed container along which gas may pass.

[0078] According to a third aspect there is provided a method of activating a vent assembly in a closed container, the method comprising the steps: providing a closed container according to the first aspect or second aspect; and exceeding the threshold such that the closed container moves from the first configuration to the second configuration, wherein in the second configuration gas from within the closed container may pass through the membrane of the closed container to the exterior.

[0079] The threshold may be a pressure threshold. Accordingly, the step of exceeding the threshold includes increasing the pressure within the closed container to exceed a threshold pressure. As a result, moving the closed container to the second configuration from the first configuration allows the pressure within the closed container to be reduced through gas passing through the membrane of the closed container.

[0080] In a fourth aspect there is provided a vent assembly for use in a closed container, the vent assembly comprising a membrane, a barrier and an assembly wall, a pathway is defined by the assembly wall and extends through the membrane and the barrier, the vent assembly having a first configuration in which the barrier at least substantially occludes the pathway and prevents or substantially prevents the passage of fluid along the pathway when the vent assembly is installed in a closed container and a second configuration in which the barrier does not occlude the pathway such that fluid may pass along the pathway when the vent assembly is installed in a closed container, wherein the vent assembly is configured to transition from the first configuration to the second configuration when a threshold is exceeded.

[0081] The assembly wall may define a first aperture. The first aperture may be adjacent to the barrier. The first aperture may be adjacent to the membrane. The vent assembly may be configured to be installed in a closed container such that the first aperture is adjacent to an aperture defined in the wall of the closed container. Accordingly, during use fluid may flow from the closed container to the vent assembly through the first aperture.

[0082] The assembly wall may define a second aperture. The second aperture may be adjacent to the membrane. The second aperture may be adjacent to the barrier. During use when the vent assembly is installed in a closed container, the pathway may extend from the interior of the closed container to the exterior of the vent assembly through the second aperture.

[0083] The closed container may be a battery.

[0084] For the avoidance of doubt the features of the closed container, membrane and barrier of the first aspect may be features of the membrane and barrier of the second and fourth aspects. Brief Description of the Figures

[0085] Embodiments of the present invention will now be described, by way of non-limiting example, with reference to the accompanying drawings.

[0086] Figure 1 : A schematic side view of a closed container according to an embodiment in a first configuration (A) and a second configuration (B);

[0087] Figure 2: A schematic top down view of a closed container according to an embodiment;

[0088] Figure 3: A schematic side view of a closed container according to an embodiment in a first configuration (A) and a zoomed in view of the seal in the second configuration (B);

[0089] Figure 4: A schematic side view of a closed container according to an embodiment in a first configuration (A) and a second configuration (B);

[0090] Figure 5: A schematic top down view of a closed container according to an embodiment;

[0091] Figure 6: A schematic side view of a closed container according to an embodiment in a first configuration;

[0092] Figure 7: A schematic top down view of a closed container according to an embodiment;

[0093] Figure 8: A schematic side view of a closed container according to an embodiment in a first configuration (A) and a second configuration (B);

[0094] Figure 9: A schematic side view of a representative vent assembly installed within a closed container moving from a first configuration (A) to a second configuration (B);

[0095] Figure 10: A schematic side view of a vent assembly according to an embodiment;

[0096] Figure 11 : A schematic side view of a representative vent assembly installed within a closed container moving from a first configuration (A) to a second configuration (B);

[0097] Figure 12: A schematic side view of a vent assembly according to an embodiment; and Figure 13: A schematic top down view of a closed container according to an embodiment.

[0098] Detailed Description

[0099] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.

[0100] To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as "a", "an" and "the" are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.

[0101] Test Methods

[0102] T-Peel Strength Test Method

[0103] The t-peel strength test method was carried out on an IMASS SP-2100 Peel Tester using the T-peel fixturing and 22 N load cell. A sample was created by laminating or adhering two materials together and then prepared for testing by cutting 10 mm wide strips. The sample strips are loaded into the tester by clamping one material into the first clamp and the second material in the laminate into the second clamp. The material was manually brought to a taught position and then the test was started. The equipment pulls the two materials apart at a rate of 1 mm / second for a total length of 14 mm. The data collection starts after a 4 second delay and the load was averaged for a total of 10 seconds. This average load was used to compare the sample’s peel strength.

[0104] Opening Pressure Test Method

[0105] The following system was used to measure the opening pressure at which the barrier fails of modified mock battery pouches. The mock battery pouches were built to represent a standard 645464 battery by utilizing a 5.6 mm thick by 52.7 mm wide by 59.6 mm long acrylic block as the mock jelly roll. This acrylic block also includes a tapped hole to accept a quick connect air fitting. Battery pouch material was sealed around the acrylic block. During the pouch construction a barrier and membrane were installed. Utilizing the tapped hole, the quick connect air fitting was attached through the pouch material and into the acrylic block. With the mock battery pouch in a box to constrain its available head space to 10% of its total thickness, compressed air was slowly flowed into the mock battery pouch. A pressure regulator and pressure gauge were used to slowly increase the pressure until the barrier failed and this pressure value was recorded for comparison to different configurations.

[0106] Moisture Vapor Transmission Rate (MVTR)

[0107] MVTR was measured according to the standard test method ASTM F1249-13.

[0108] Instrument (any is acceptable):

[0109] Mocon PERMATRAN-W 3 / 34 G

[0110] GTR Tec GTR-30XAGR Moisture (gaseous H2O) permeability was measured where a sample material divides a chamber into a high humidity section and a low humidity section where a dry gas is flowed across the sample material. Moisture that passes through the material to the low humidity section is measured by relative humidity detection (Mocon) or gas chromatography (GTR Tec).

[0111] Gas Transmission Rate (GTR)

[0112] GTR was measured according to the standard test method ASTM D1434-82 or ASTM F2476. Instrument (any is acceptable):

[0113] 1 . Labthink VAC-V2

[0114] 2. GTR Tec GTR-30XAGR

[0115] 3. GTR Tec GTR-11MJGG

[0116] 4. Mocon Permatran-C 4 / 41

[0117] Gas (CO2, N2, O2) permeability was measured using a gas detector at 40°C. A sample material is placed in an evaluation cell to cover an aperture. Gas is supplied into the evaluation cell to create a pressure differential. For Labthink and GTR Tec instrument, gas that passes through the material to the low pressure section is measured by pressure sensor (Labthink) or gas chromatography (GTR Tec). For Mocon instrument, gas is supplied into the evaluation cell to create a concentration gradient with measurement under isobaric conditions. Gas that passes through the material to the low concentration section is measured by gas sensor.

[0118] Method of calculating CO2 / H2O selectivity

[0119] The CO2 to H2O selectivity of a sample material was calculated by converting the CO2 gas transmission rate (GTR, units of cm3 / (m2x 24h x atm)) of the sample material and moisture vapor transmission rate (MVTR, units of g / (m2x day)) of the sample material into respective permeability coefficients (CO2: units of cm3 / (cm2x s x cmHg), moisture: units of g / (cm2x s x cmHg)) and the selectivity is calculated as the CO2 permeability coefficient divided by the moisture permeability coefficient. This method may be used to calculate selectivity between other gases such as CO2 / O2 or CO2 / N2, for example.

[0120] Airflow

[0121] The ATEQ airflow test measures laminar volumetric flow rates of air through membrane samples. Each membrane sample was clamped between two plates in a manner that seals an area of 2.99 cm2across the flow pathway. An ATEQ® (ATEQ Corp., Livonia, Ml) Premier D Compact Flow Tester was used to measure airflow rate (L / hr) through each membrane sample by challenging it with a differential air pressure of 1.2 kPa (12 mbar) through the membrane. The instrument was operated with calibrated 30 and 150 L flow tubes for making airflow measurements within the ranges of 0.5 to 30 L / hr and 3.8 to 150 L / hr, respectively.

[0122] It will be appreciated that the schematic representations of the membranes, barriers and closed containers shown in the Figures are not to scale and are for illustrative purposes only.

[0123] Example 1

[0124] With reference to Figures 1 and 2, a battery pouch cell 1 (acting as a closed container) comprises a pouch wall 2 (acting as a housing wall), a jelly roll, a membrane 4 and a barrier 6. The pouch wall 2 comprises polypropylene / aluminium / nylon laminate 88 pm thick obtained from Dai Nippon Printing (D-EL35H(3)A) with the polypropylene on the interior of the pouch wall 2. The pouch wall 2 was sealed around the periphery of the battery pouch cell 1 to form a seal 8. A passage 10 (acting as an aperture) was formed in the seal 8 between the interior of the battery pouch cell 1 and the exterior. The membrane 4 had a thickness of 27 pm and comprises an expanded polytetrafluoroethylene (PTFE) layer 12 (acting as an open layer) and a dense PTFE layer 14 (acting as a dense layer) as described in WO 2022 / 224012 to W. L. Gore & Associates, Inc. which is incorporated by reference herein in its entirety. The expanded PTFE layer 12 is adhered to the dense PTFE layer 14 by a thin layer of fluorinated ethylene propylene (FEP) 16. The membrane 4 is integrated within the passage 10 using an impulse sealer at a temperature of 200°C for 10 seconds. The barrier 6 comprised an acrylic adhesive 10 pm thick (SDK97C01 obtained from TaiCang Sidike New Materials Science and Technology Co., Ltd.) and was integrated within the passage 10 between the membrane 4 and the exterior of the battery pouch cell 1 using a roller at room temperature followed by impulse sealing the edges of the barrier 6 at 200°C for 10 seconds.

[0125] The membrane 4 had the following properties. CO2 and H2O permeability were measured at 40°C, and it was found that CO2 GTR is 24500 cm3 / m2 / day / atm, and MVTR is 2.4 g / m2 / day. The calculated CO2 / H2O selectivity is 744 cm3 / g, which is high among polymer films and ideal for the application in battery pouch cells, since it maximizes CO2 release while minimizing ingress of water vapor. Airflow was also measured according to the method above and it was zero. This confirms the membrane is nonporous and suitable for the application in battery pouch cells because it can contain electrolyte within the cell.

[0126] For testing purposes the jelly roll of the battery pouch cell was replaced with a mock jelly roll 18 comprising an acrylic sheet. During use the barrier 6 is configured to fail once a threshold pressure has been exceeded to allow gas to pass along a pathway 20 from the interior of the battery pouch cell 1 to the exterior of the battery pouch cell 1 (see Figure 1 B). When the barrier 6 fails it forms a first barrier portion 22 and a second barrier portion 24 and the pathway 20 extends between the first barrier portion 22 and the second barrier portion 24.

[0127] According to the test method described above, the internal pressure within the battery pouch cell 1 was increased until the barrier 6 failed. The pressure at which the barrier 6 failed and the seal 8 was observed to open was recorded at 0.81 bar.

[0128] Example 2

[0129] With reference to Figure 3 a battery pouch cell 50 (acting as a closed container) comprises a pouch wall 52 (acting as a housing wall), a jelly roll 54, a membrane 56 and a barrier 58. The pouch wall 52 comprises polypropylene / aluminium / nylon laminate 88 pm thick obtained from Dai Nippon Printing (D-EL35H(3)A) with the polypropylene on the interior of the pouch wall 52. The pouch wall 52 was sealed around the periphery of the battery pouch cell 50 to form a seal (not shown). A passage 60 (acting as an aperture) was formed in the seal between the interior of the battery pouch cell 50 and the exterior. The membrane 56 comprises an expanded polytetrafluoroethylene (PTFE) layer 62 (acting as an open layer) and a dense PTFE layer 64 (acting as a dense layer) as described in WO 2022 / 224012 to W. L. Gore & Associates, Inc. which is incorporated by reference herein in its entirety. The expanded PTFE layer 62 is adhered to the dense PTFE layer 64 by a thin layer of fluorinated ethylene propylene (FEP) 66. The membrane 56 corresponds to the membrane 4 of Example 1 above. The membrane 56 is integrated within the passage 60 using an impulse sealer at a temperature of 200°C for 10 seconds. The barrier 58 comprises a PP / PE / PP laminate that was made by laminating one layer of 60 pm polyethylene (PE) film between two layers of 1.5 mil (38 pm) polypropylene (PP) film (obtained from LILINE) using a hot press at a temperature of 130°C for 15 seconds. The barrier 58 was integrated within the passage 60 between the membrane 56 and the interior of the battery pouch cell 50 using an impulse sealer at a temperature of 190°C for 10 seconds.

[0130] The barrier 58 is configured to fail (see Figure 3B, for example) when the pressure within the battery cell pouch exceeds a threshold pressure and breaks about the connection between the PE and PP in the barrier 58 (acting as a fault element) into a first barrier portion 70 comprising PP 70a and PE 70b and a second barrier portion 72 comprising PP 72a alone. The space 74 between the first barrier portion 70 and the second barrier portion 72 allows fluid to flow along a pathway 76 to the membrane 56. Example 3

[0131] With reference to Figures 4 and 5 a battery pouch cell 100 (acting as a closed container) comprises a pouch wall 102 (acting as a housing wall), a jelly roll 104, a membrane 106 and a barrier 108. The pouch wall 102 comprises polypropylene / aluminium / nylon laminate 88 pm thick (obtained from Dai Nippon Printing (D-EL35H(3)A)) with the polypropylene on the interior of the pouch wall 102. The pouch wall 102 was sealed around the periphery of the battery pouch cell 100 to form a seal (not shown). An aperture 110 was formed in the pouch wall 102. The membrane 106 comprises a 1.5 mil (38 pm) polypropylene film (obtained from LILINE). The membrane 106 spans the aperture 110 and is heat welded in place using an impulse sealer at a temperature of 200°C for 10 seconds. The barrier 108 comprised a polyethylene film 60 pm thick and was bonded to the interior surface of the pouch wall 102 using an impulse sealer at a temperature of 130°C for 10 seconds. The barrier 108 is positioned between the membrane 106 and jelly roll 104 defining a first volume 112 defined between the pouch wall 102, the barrier 108 and the membrane 106. A second volume 114 is defined between the barrier 108 and the pouch wall 102 and the jelly roll 104 is retained within the second volume 114.

[0132] The barrier 108 is configured to detach from the pouch wall 102 when the pressure within the battery pouch cell 100 exceeds a threshold pressure to form a pathway 116 between the barrier and the pouch wall 102 to thereby allow fluid from the second volume 114 to flow into the first volume 112 (see Figure 4B). Gas may then pass through the membrane 106 and the aperture 110 to the exterior of the battery pouch cell 100.

[0133] Example 4

[0134] With reference to Figures 6 and 7 a battery pouch cell 150 (acting as a closed container) comprises a pouch wall 152 (acting as a housing wall), a jelly roll 154, a membrane 156 and a barrier 158. The pouch wall 152 comprises polypropylene / aluminium / nylon laminate 88 pm thick (obtained from Dai Nippon Printing (D-EL35H(3)A)) with the polypropylene on the interior of the pouch wall 152. The pouch wall 152 was sealed around the periphery of the battery pouch cell 150 to form a seal (not shown). An aperture 160 was formed in the pouch wall 152. The membrane 156 comprises expanded polytetrafluoroethylene (ePTFE). The membrane 156 spans the aperture 160 and is heat welded in place using an impulse sealer at a temperature of 200°C for 10 seconds. The barrier 158 comprised polypropylene and was formed by heat welding the interior polypropylene surfaces of the pouch wall 152 together using a 0.1 mm tool thickness at 400°C with a force of 30N for 0.05 seconds. The barrier 158 is positioned between the membrane 156 and jelly roll 154 defining a first volume 162 defined between the pouch wall 152, the barrier 158 and the membrane 156. A second volume 164 is defined between the barrier 158 and the pouch wall 152 and the jelly roll 154 is retained within the second volume 164.

[0135] The barrier 158 is configured to detach from the pouch wall 152 or rupture when the pressure within the battery pouch cell 150 exceeds a threshold pressure to form a pathway 166 between the barrier and the pouch wall 152 to thereby allow fluid from the second volume 164 to flow into the first volume 162. Gas may then pass through the membrane 156 and the aperture 160 to the exterior of the battery pouch cell 150.

[0136] A modified version of the above battery pouch cell 150 was tested using test method described above. The jelly roll 154 and the membrane 156 were removed for this test and the pressure when the barrier 158 failed was determined to be 0.063 bar.

[0137] Example 5

[0138] Referencing Figure 8 a pouch 200 (acting as a closed container) comprises a pouch wall 202, a membrane 204, and barrier 206. The pouch wall 202 comprises polypropylene and forms a first wall portion 208 and a second wall portion 210 that abut one another in a first configuration to form a seam 212. The membrane 204 comprises expanded polyethylene was positioned on the inside of the seam 212. The barrier 206 comprises an epoxy adhesive and is provided on the outside of the seam 212 sealing the seam 212 against exterior contaminants.

[0139] When the pressure within the pouch 200 exceeds a threshold pressure the pouch wall 202 swells such that the pouch wall 202 flexes about the seam 212. As the pouch wall 202 moves to a second configuration and flexes about the seam 212 the barrier 206 breaks (see Figure 8B), thereby creating a pathway 214 through the seam 212 and the membrane 204 along which gas may pass from within the pouch 200 to exterior of the pouch 200, thereby relieving the pressure and preventing bursting of the pouch 200.

[0140] With reference to Figure 9, for the avoidance of doubt regarding the mode by which the membranes of the examples and embodiments move from a closed configuration and an open configuration where the housing wall comprises a flexible material, a schematic general representation of a vent assembly installed within a closed container 252 is shown in a closed configuration 254 (Figure 9A) where there is slack in the membrane 260 and an open configuration 256 (Figure 9B). A fixed portion 258 of the membrane 260 of the vent assembly 250 is fixed to the interior surface of the wall 262 of the closed container 252 and a free portion 264 of the membrane 260 is not fixed. When the closed container 254 moves from the first configuration to the second configuration the walls 262 of the closed container 254 move apart from one another such that the vent assembly 250 moves to the open configuration 256 within which the fixed portion 258 of the membrane 260 remains fixed and the free portion 264 of the membrane 260 opens up to allow the membrane 260 to adopt the open configuration 256 and induces the barrier 266 to fail.

[0141] With reference to Figure 10, a vent assembly 300 comprises a housing wall 302, a barrier 304 and a membrane 306. The housing wall defines a first aperture 308 and a second aperture 310 and a pathway is defined between the first aperture 308 to the second aperture 310 through the barrier 304 and membrane 306. The membrane 306 occludes the second aperture 310. A first volume 312 is defined between the barrier 304, the housing wall 302 and the membrane 306.

[0142] The vent assembly 300 is configured to be installed onto the housing wall of a closed container (not shown) to thereby provide a pathway from the interior of the closed container to the exterior of the closed container through the vent assembly 300 via the first aperture 308 and the second aperture 310.

[0143] Example 6

[0144] With reference to Figures 11 and 12 a battery pouch cell 350 (acting as a closed container) comprises a pouch wall 352 (acting as a housing wall), a jelly roll 354, a membrane 356 and a barrier 358. The barrier 358 was teardrop shaped and oriented such that the long axis of the teardrop runs in the direction from the jelly roll 354 to the edge of the battery pouch cell 350. A space 359 is defined between the jelly roll 354 and the membrane 356. The pouch wall 352 comprises polypropylene / aluminium / nylon laminate 88 pm thick (obtained from Dai Nippon Printing (D-EL35H(3)A)) with the polypropylene on the interior of the pouch wall 352. The pouch wall 352 was sealed around the periphery of the battery pouch cell 350 to form a seal (not shown). An aperture 360 was formed in the pouch wall 352. The membrane 356 comprises an expanded polytetrafluoroethylene (PTFE) layer (acting as an open layer) and a dense PTFE layer (acting as a dense layer) as described in WO 2022 / 224012 to W. L. Gore & Associates, Inc. which is incorporated by reference herein in its entirety. The expanded PTFE layer is adhered to the dense PTFE layer by a thin layer of fluorinated ethylene propylene (FEP). The membrane 356 spans the aperture 360 and is heat welded in place with the open layer of the membrane facing the PP layer of the pouch laminate, using an impulse sealer at a temperature of 200°C for 10 seconds. With reference to Figure 11 the barrier 358 is positioned on the outside of the pouch wall 352 over the aperture 360. The barrier is adhered to the pouch wall 352 with a ring of 25-micron thick rubber-based pressure sensitive adhesive 362. The barrier consists of the rubber-based pressure sensitive adhesive 362, two layers of 254-micron polypropylene film 364 bonded together with a 30-micron thick acrylic pressure sensitive adhesive 366, and a single layer of 3M 3311 aluminium foil Wh tape 368. This material forms a stiff barrier that is less flexible than the pouch wall 352 laminate.

[0145] The barrier 358 is configured to detach from the pouch wall 352 when the pressure within the battery pouch cell 350 deforms the pouch material to cause the more rigid barrier 358 to delaminate, forming a pathway 370 between the barrier 358 and the pouch wall 352 to thereby expose membrane 356 to the outside environment. Gas may then pass through the membrane 356 and the aperture 360 to the exterior of the battery pouch cell 350.

[0146] Figure 13 shows a top down view of the battery pouch cell 350. A pair of electrodes 370 extend from the battery pouch cell 250.

[0147] A modified version of the above battery pouch cell 350 was tested using test method described above. The jelly roll 354 and the membrane 356 were removed for this test and the pressure when the barrier 358 failed was determined to be 0.14 bar.

[0148] Table 1 : Change in gas transmission rate for Example 6 before and after barrier fail (“closed” and “Open” respectively)aPTFE / FEP laminate has a thickness of 16 pm. It comprises an expanded polytetrafluoroethylene (PTFE) layer (acting as an open layer) and a dense PTFE layer (acting as a dense layer) as described in WO 2022 / 224012 to W. L. Gore & Associates, Inc. which is incorporated by reference herein in its entirety. The expanded PTFE layer is adhered to the dense PTFE layer by a thin layer of fluorinated ethylene propylene (FEP).bAI / PP / Adhesive comprises a layer of aluminum (Al) foil tape (3311 obtained from 3M), a layer of polypropylene (254 pm thick, 1451T61 obtained from McMaster Carr), a layer of acrylic pressure sensitive adhesive (30 pm thick, 4983 obtained from Tesa), another layer of polypropylene (254 pm thick, 1451T61 obtained from McMaster Carr), and a layer of rubberbased adhesive (25 pm thick, ARclear EL-44010 obtained from Adhesives Research).

[0149] As can be seen in Table 1 above, before the barrier 358 fails the barrier 358 is substantially preventing passage of gas through the aperture 360 of the battery pouch cell 350. When the pressure differential across the barrier 358 exceeds 0.14 bar, the barrier 358 detaches from the housing and the gas transmission rate greatly increases to thereby relieve the pressure and preventing the pressure within the battery pouch cell 350 exceeding dangerous pressures.

[0150] For the above examples, it will be appreciated that the provision of a membrane that comprises a material that has good gas permeability (validated by using the test methods provided above) but is liquid impermeable allows the closed container of each example to continue operation after the barrier has failed as the membrane will prevent any liquid retained within the closed container escaping whilst continuing to allow gas generated within the closed container to escape.

[0151] Furthermore, if the membrane comprises a material with good selectivity between carbon dioxide and water (as validated using the test methods described above) gas such as carbon dioxide generated within the closed container can escape through the membrane whilst the ingress of water vapour into the closed container through the membrane will be minimized.

[0152] While there has been hereinbefore described approved embodiments of the present invention, it will be readily apparent that many and various changes and modifications in form, design, structure and arrangement of parts may be made for other embodiments without departing from the invention and it will be understood that all such changes and modifications are contemplated as embodiments as a part of the present invention as defined in the appended claims.

Claims

Claims1 . A closed container comprising a housing wall defining an aperture, a membrane, and a barrier, a pathway is defined by the housing wall between the interior of the closed container and the exterior of the closed container through the aperture, the membrane and the barrier being positioned within the pathway such that the membrane and the barrier substantially occlude the pathway, the closed container configured to move between a first configuration where the barrier prevents passage of fluid along the pathway to the exterior of the closed container and a second configuration where the barrier does not prevent passage of fluid along the pathway to the exterior of the closed container and the membrane remains in the pathway, wherein the closed container is configured to transition from the first configuration to the second configuration when a threshold is exceeded.

2. The closed container of claim 1 , wherein the closed container is a battery.

3. The closed container of claim 2, wherein the closed container is a battery pouch cell.

4. The closed container of any of preceding claim, wherein the threshold is a pressure threshold and the closed container transitions from the first configuration to the second configuration when the pressure within the closed container is greater than the pressure threshold.

5. The closed container of claim 4, wherein the pressure threshold is at least 0.01 bar.

6. The closed container of claim 4 or claim 5, wherein the pressure threshold is from 0.01 to 6 bar.

7. The closed container of any preceding claim, wherein the barrier is more rigid than the housing wall.

8. The closed container of claim 7, wherein the barrier substantially does not flex or bend when the closed container moves from the first configuration to the second configuration.

9. The closed container of claim 7 or claim 8, wherein the barrier has an irregular shape, optionally a teardrop shape.

10. The closed container of any of claim 7 to claim 9, wherein the barrier comprises at least one polymer layer and at least one metallic layer.11 . The closed container of any preceding claim, wherein the barrier, the membrane and a first portion of the housing wall define a first enclosed volume, and the barrier and a second portion of the housing wall define a second enclosed volume separated from the first enclosed volume by the barrier.

12. The closed container of any preceding claim, wherein the aperture is defined within a portion of the housing wall and the membrane spans the aperture in both the first configuration and the second configuration.

13. The closed container of any of claims 1 to 11 , wherein the housing wall comprises a plurality of housing wall portions and the aperture is defined between adjacent housing wall portions.

14. The closed container of claim 13, wherein the barrier occludes or substantially occludes the aperture when the closed container is in the first configuration.

15. The closed container of any preceding claim, wherein the barrier fails when the threshold is exceeded and the closed container transitions from the first configuration to the second configuration to thereby no longer substantially occlude the pathway.

16. The closed container of claim 15, wherein the barrier breaks when the threshold is exceeded to thereby no longer substantially occlude the pathway.

17. The closed container of claim 16, wherein the barrier breaks into a first barrier portion and a second barrier portion when the threshold is exceeded.

18. The closed container of claim 15, wherein the barrier is fixed to opposing portions of the housing wall to thereby span the closed container and the barrier detaches from the housing wall when the threshold is exceeded.

19. The closed container of any preceding claim, wherein the membrane is connected to two opposing walls of the housing wall or two opposing portions of the housing wall and the membrane is in a closed configuration when the closed container is in the firstconfiguration and the membrane is in an open configuration when the closed container is in the second configuration.

20. The closed container of any preceding claim, wherein the membrane is sealed against the housing wall around at least the periphery of the membrane.

21. The closed container of any preceding claim, wherein the membrane comprises a polymer selected from the group: polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), or polyethylenetetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and poly(tetramethyl-p-silphenylenesiloxane) (PTMPS) or co-polymers or combinations thereof.

22. The closed container of any preceding claim, wherein the barrier comprises a material selected from the group: thermoset adhesive, acrylic based adhesive, epoxy, urethane-based adhesive, rubber adhesive, silicone-based adhesive, metal foils including aluminium foil, laminated metal foils, fluorinated ethylene propylene (FEP), ethylene fluorinated ethylene propylene (EFEP), PTFE and co-polymers of tetrafluoroethylene (TFE), polyethylene (PE), polypropylene (PP), polybutene-1 , polyolefin blends, or combinations or co-polymers thereof.

23. A closed container comprising a housing wall, a membrane and a barrier, the housing wall comprising two opposed edges, the two opposed edges abutting one another to form a seam, the membrane being provided on a first side of the seam and the barrier being provided on a second side of the seam, the seam and the barrier preventing passage of fluid into or out of the closed container in a first configuration, the barrier being configured to break and a space to be formed between the two opposed edges of the housing wall in a second configuration when the pressure within the closed container exceeds a threshold pressure and a pathway is formed from within the closed container, through the membrane and the space between the two opposed edges of the housing wall to the exterior of the closed container along which gas may pass.

24. A vent assembly for use in a closed container, the vent assembly comprising a membrane, a barrier and a housing wall, a pathway is defined by the housing wall and extends through the membrane and the barrier, the vent assembly having a firstconfiguration in which the barrier at least substantially occludes the pathway and prevents or substantially prevents the passage of fluid along the pathway when the vent assembly is installed in a closed container and a second configuration in which the barrier does not occlude the pathway such that fluid may pass along the pathway when the vent assembly is installed in a closed container, wherein the vent assembly is configured to transition from the first configuration to the second configuration when a physical threshold is exceeded.

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