Battery Housing and Venting Elements

Abstract

Provided is a battery housing comprising a housing wall, the housing wall comprising an impermeable substrate and at least one aperture disposed in the impermeable substrate, the or each aperture extending from a first side of the impermeable substrate to a second side of the impermeable substrate, the or each aperture having a maximum width of from 0.1 μm to 100 μm, and the housing wall having a ratio of carbon dioxide (CO2) permeability to water vapor (moisture) permeability of at least 2 using the test method described herein.

Description

[Technical Field]

[0001] Field The present disclosure relates to battery housings for use in batteries, and more particularly to battery housings that allow gases to escape from within the battery housing during use. [Background technology]

[0002] background Batteries, such as lithium-ion batteries, are used as power sources for a wide range of electronic devices, including automobiles and mobile phones. Although battery performance has improved dramatically over the past few decades, improvements in several aspects of battery performance (e.g., battery life, battery power output, etc.) are still needed.

[0003] For example, in batteries containing electrolytes that may release one or more gases during operation, these gases can increase pressure within the battery housing, which, if left unchecked, could lead to the battery housing exploding. Therefore, it is important to be able to vent such gases and reduce the pressure within the battery housing.

[0004] However, vents or covers typically used in the art to release gases generated by electrolyte decomposition can allow water vapor to enter the battery housing, adversely affecting battery performance and lifespan.

[0005] Therefore, there remains a need for improved batteries and improved battery housings that further minimize water ingress while providing good release of gases evolved from the electrolyte.

[0006] Thus, at least some embodiments described herein provide an improved solution for venting internal gases while minimizing water vapor ingress into the battery housing. Summary of the Invention

[0007] Abstract According to a first aspect, there is provided a battery housing comprising a housing wall, the housing wall comprising an impermeable substrate and at least one aperture disposed in the impermeable substrate, the or each aperture extending from a first side of the impermeable substrate to a second side of the impermeable substrate, the housing wall having a ratio of carbon dioxide (CO2) transmission rate to water vapor (moisture) transmission rate of at least 2, using the test method described herein.

[0008] The or each hole may have a maximum width of less than 100 μm. The or each hole may have a maximum width of less than 80 μm. The or each hole may have a maximum width of less than 60 μm. The or each hole may have a maximum width of less than 40 μm. The or each hole may have a maximum width of less than 20 μm.

[0009] The hole or each hole may have a maximum width of 0.1 μm to 100 μm. The hole or each hole may have a maximum width of 0.1 μm to 75 μm. The hole or each hole may have a maximum width of 0.1 to 50 μm. The hole or each hole may have a maximum width of 0.1 to 40 μm. The hole or each hole may have a maximum width of 0.1 to 30 μm. The hole or each hole may have a maximum width of 0.1 to 20 μm. The hole or each hole may have a maximum width of 0.1 to 15 μm. The hole or each hole may have a maximum width of 0.1 to 10 μm. The hole or each hole may have a maximum width of 0.1 to 9 μm. The hole or each hole may have a maximum width of 0.1 to 8 μm. The hole or each hole may have a maximum width of 0.1 to 7 μm. The hole or each hole may have a maximum width of 0.1 to 6 μm. The or each hole may have a maximum width of 0.1 to 5 μm. The or each hole may have a maximum width of 1 to 100 μm. The or each hole may have a maximum width of 2 to 100 μm. The or each hole may have a maximum width of 3 to 100 μm. The or each hole may have a maximum width of 4 to 100 μm. The or each hole may have a maximum width of 5 to 100 μm.

[0010] The or each pore may have an effective diameter of less than 100 μm. The or each pore may have an effective diameter of less than 80 μm. The or each pore may have an effective diameter of less than 60 μm. The or each pore may have an effective diameter of less than 40 μm. The or each pore may have an effective diameter of less than 20 μm.

[0011] The hole or each hole may have an effective diameter of 0.1 μm to 100 μm. The hole or each hole may have an effective diameter of 0.1 μm to 75 μm. The hole or each hole may have an effective diameter of 0.1 to 50 μm. The hole or each hole may have an effective diameter of 0.1 to 40 μm. The hole or each hole may have an effective diameter of 0.1 to 30 μm. The hole or each hole may have an effective diameter of 0.1 to 20 μm. The hole or each hole may have an effective diameter of 0.1 to 15 μm. The hole or each hole may have an effective diameter of 0.1 to 10 μm. The hole or each hole may have an effective diameter of 0.1 to 9 μm. The hole or each hole may have an effective diameter of 0.1 to 8 μm. The hole or each hole may have an effective diameter of 0.1 to 7 μm. The hole or each hole may have an effective diameter of 0.1 to 6 μm. The or each hole may have an effective diameter of 0.1 to 5 μm. The or each hole may have an effective diameter of 1 to 100 μm. The or each hole may have an effective diameter of 2 to 100 μm. The or each hole may have an effective diameter of 3 to 100 μm. The or each hole may have an effective diameter of 4 to 100 μm. The or each hole may have an effective diameter of 5 to 100 μm.

[0012] As used herein, the term "effective diameter" refers to the diameter of a hole when it is approximated as a circle from its measured cross-sectional area.

[0013] As used herein, the term "pore" refers to a pathway or channel that allows the passage of a fluid from a first side of a substrate to a second side of the substrate. The pathway is linear, allowing the fluid to pass through the substrate in a substantially straight line. As used herein, the term "pore" does not include pores that provide a tortuous path through a porous substrate, but rather includes pores that are more linear.

[0014] The or each hole may be formed as a linear path through the non-permeable substrate, the or each hole may be formed in or through the non-permeable substrate after the non-permeable substrate is formed, and therefore the or each hole is not a pore of, for example, a porous material.

[0015] The or each hole may have any cross-sectional shape. The or each hole may have a substantially circular or elliptical cross-section. The or each hole may have an angular cross-sectional shape having any number of sides, such as a triangle, rectangle (square or oblong), pentagon, hexagon or octagon. The or each hole may have an irregular cross-sectional shape.

[0016] The or each hole may include a generally cylindrical portion. The or each hole may be generally cylindrical. Thus, the or each hole may have substantially the same maximum width and substantially the same cross-sectional area as the or each hole when the or each hole extends from the first surface to the second surface of the non-permeable substrate.

[0017] The or each hole may include a generally conical portion. The or each hole may be generally conical. Accordingly, the maximum width of the or each hole may increase or decrease as it extends from the first surface to the second surface.

[0018] The or each hole may be formed in the non-transparent substrate by any suitable method. The or each hole may be formed by mechanical drilling. The or each hole may be formed by laser drilling. In embodiments in which the or each hole is formed by laser drilling, the maximum width of the or each hole may decrease slightly from the first surface on which the laser is incident to the second surface as the laser is attenuated as it passes through the non-transparent substrate. Thus, the or each hole may have a first maximum width or effective diameter at the first surface of the non-transparent substrate and a second maximum width or effective diameter at the second surface of the non-transparent substrate. The first maximum width or effective diameter may be larger than the second maximum width or effective diameter. The first maximum width or effective diameter may be smaller than the second maximum width or effective diameter.

[0019] The or each hole may be formed by piercing the non-permeable substrate. The or each hole may be formed by piercing the non-permeable substrate by forcing or biasing a piercing element through the non-permeable substrate. The piercing element may be a needle, capillary tube or the like.

[0020] In embodiments in which a plurality of holes is provided in the non-permeable substrate, the plurality of holes may be formed by an array of perforation elements, which may be arranged in a regular pattern such that the plurality of holes provided in the non-permeable substrate are arranged in a regular pattern.

[0021] The housing wall may include at least two holes disposed in the non-permeable substrate. The housing wall may include at least three holes disposed in the non-permeable substrate. The housing wall may include at least four holes disposed in the non-permeable substrate. The housing wall may include at least five holes disposed in the non-permeable substrate. The housing wall may include at least six holes disposed in the non-permeable substrate. The housing wall may include at least seven holes disposed in the non-permeable substrate. The housing wall may include at least eight holes disposed in the non-permeable substrate. The housing wall may include at least nine holes disposed in the non-permeable substrate. The housing wall may include at least ten holes disposed in the non-permeable substrate.

[0022] The housing wall may include 1 to 100 holes formed in the non-transparent substrate. The housing wall may include 1 to 75 holes formed in the non-transparent substrate. The housing wall may include 1 to 50 holes formed in the non-transparent substrate. The housing wall may include 1 to 40 holes formed in the non-transparent substrate. The housing wall may include 1 to 30 holes formed in the non-transparent substrate. The housing wall may include 1 to 20 holes formed in the non-transparent substrate. The housing wall may include 1 to 15 holes formed in the non-transparent substrate. The housing wall may include 1 to 10 holes formed in the non-transparent substrate.

[0023] In some embodiments, the housing wall can include one hole in the non-transparent substrate. In some embodiments, the housing wall can include two holes in the non-transparent substrate. In some embodiments, the housing wall can include three holes in the non-transparent substrate. In some embodiments, the housing wall can include four holes in the non-transparent substrate. In some embodiments, the housing wall can include five holes in the non-transparent substrate.

[0024] As used herein, the "ratio of CO2 permeability to water vapor permeability" is calculated by dividing the CO2 permeability of a substrate by the water vapor permeability. The ratio of CO2 permeability to water vapor permeability is unitless (i.e., dimensionless). Thus, a ratio of at least 2 means that at a given pressure, at least twice the volume of CO2 passes through the housing wall as the volume of water vapor.

[0025] Typically, the battery housing defines an enclosed space capable of holding an electrolyte.

[0026] It is important to prevent water, whether in liquid or vapor form, from entering the interior of the battery housing, as its presence can significantly affect the efficiency and performance of the battery.

[0027] Additionally, during the life of the battery, gases such as carbon dioxide (CO), hydrogen (H), carbon monoxide (CO), or methane (CH) may be produced as by-products of the electrochemical reactions within the battery housing. To ensure that the pressure within the battery housing remains within operational limits and to prevent rupture of the housing walls, it is advantageous for the gases to be able to vent from within the battery housing.

[0028] Surprisingly, it has been found that battery housings according to embodiments of the present invention are capable of minimizing the ingress of water into the interior of the battery housing while allowing gases to escape.

[0029] CO2 transmission through the housing wall is at least 25cm 3 / day. The CO2 transmission rate through the housing wall must be at least 50 cm 3 / day. The CO2 transmission rate through the housing wall must be at least 75 cm 3 / day. The CO2 permeability through the housing wall must be at least 100 cm 3 / day. The CO2 transmission rate through the housing wall must be at least 150 cm 3 / day. The CO2 permeability through the housing wall must be at least 200 cm 3 / day. The CO2 transmission rate through the housing wall is 25 cm 3 / day~10,000cm 3 / day. The CO2 transmission rate through the housing wall is 50 cm 3 / day~10,000cm 3 / day. The CO2 transmission rate through the housing wall is 75 cm 3 / day~10,000cm 3 / day. The CO2 permeability through the housing wall is 100 cm 3 / day~10,000cm 3 / day. The CO2 permeability through the housing wall is 150 cm 3 / day~10,000cm 3 / day. The CO2 permeability through the housing wall is 200 cm 3 / day~10,000cm 3 / day can be.

[0030] CO2 permeability is typically 37.8°C, 5cm 2 The surface area of ​​a material is measured at a pressure of 1 bar. 3 When the unit " is used, it should be understood that this is the volume of gas at standard temperature and pressure (hereinafter defined as a temperature of 0°C and a pressure of 1 bar).

[0031] The CO2 permeability through the housing wall is at least 50,000 cm³ at standard temperature and pressure. 3 / (m 2 The CO2 permeability through the housing wall can be at least 75,000 cm 3 / (m 2 The CO2 permeability through the housing wall can be at least 100,000 cm 3 / (m 2The CO2 permeability through the housing wall can be at least 150,000 cm 3 / (m 2 The CO2 permeability through the housing wall can be at least 200,000 cm 3 / (m 2 The CO2 permeability through the housing wall is 25,000 cm 3 / (m 2 ·day·bar) ~10,000,000 cm 3 / (m 2 The CO2 permeability through the housing wall is 50,000 cm 3 / (m 2 ·day·bar) ~10,000,000 cm 3 / (m 2 The CO2 permeability through the housing wall is 75,000 cm 3 / (m 2 ·day·bar) ~10,000,000 cm 3 / (m 2 The CO2 permeability through the housing wall can be 100,000 cm 3 / (m 2 ·day·bar) ~10,000,000 cm 3 / (m 2 The CO2 permeability through the housing wall is 150,000 cm 3 / (m 2 ·day·bar) ~10,000,000 cm 3 / (m 2 The CO2 permeability through the housing wall is 200,000 cm 3 / (m 2 ·day·bar) ~10,000,000 cm 3 / (m 2 ·Sun·Bar).

[0032] It will be appreciated that it is desirable to have as low a water vapor transmission rate through the housing wall as possible. For example, a water vapor transmission rate of 200,000 cm 3 / (m 2 The water vapor transmission rate through the housing wall can be less than 150,000 cm 3 / (m 2 The water vapor transmission rate through the housing wall can be less than 100,000 cm 3 / (m 2 The water vapor transmission rate through the housing wall can be less than 75,000 cm 3 / (m 2 ·day·bar).

[0033] The housing wall can have a ratio of CO2 permeability to moisture permeability of at least 3. The housing wall can have a ratio of CO2 permeability to moisture permeability of at least 5. The housing wall can have a ratio of CO2 permeability to moisture permeability of at least 10. The housing wall can have a ratio of CO2 permeability to moisture permeability of at least 20. The housing wall can have a ratio of CO2 permeability to moisture permeability of at least 30. It will be appreciated that in this application it is desirable to have this ratio as high as possible to maximize the rate of CO2 migration from the cell housing through the housing wall while simultaneously minimizing the rate of water migration into the cell housing.

[0034] The ratio of the CO2 permeability to the moisture permeability of the housing wall may be 2 to 1000. The ratio of the CO2 permeability to the moisture permeability of the housing wall may be 3 to 1000. The ratio of the CO2 permeability to the moisture permeability of the housing wall may be 5 to 1000. The ratio of the CO2 permeability to the moisture permeability of the housing wall may be 10 to 1000. The ratio of the CO2 permeability to the moisture permeability of the housing wall may be 20 to 1000. The ratio of the CO2 permeability to the moisture permeability of the housing wall may be 30 to 1000. The ratio of the CO2 permeability to the moisture permeability of the housing wall may be 50 to 1000.

[0035] As discussed herein, CO2 permeability is the CO2 permeability measured at 37.8°C using the method described below. As discussed herein, moisture or water vapor permeability is the moisture or water vapor permeability measured at 37.8°C using the method described below. Gas volumes were converted from the measurement temperature to standard temperature and pressure as described above.

[0036] As used herein, the term "impermeable substrate" refers to a substrate that has a low water vapor transmission rate. As used herein, a low water vapor (moisture) transmission rate is greater than or equal to 5 g / (m 2 ) at 37.8°C and 100% RH. 2 ·days) or less than 100,000g / (m 2 This is understood to be a water vapor transmission rate of less than 100 kJ / h (100 kJ / h).

[0037] The impermeable substrate can comprise a polymer. The polymer can be a fluoropolymer. The polymer can be a non-fluoropolymer. The polymer can be an expanded (expanded, swollen, stretched, or foamed) polymer. The polymer can be a densified expanded polymer.

[0038] For the avoidance of doubt, the term "densified expanded polymer membrane" refers to a polymer membrane that has been expanded below its melting point and then densified after expansion. It will therefore be understood that the density of at least one densified expanded polymer membrane is greater than the density of a corresponding undensified expanded polymer membrane. Those skilled in the art will appreciate that a polymer membrane expanded below its melting point and then densified may have a lower porosity than a corresponding undensified polymer membrane expanded with the same material. The densification process may result in the closure of some of the pores in the expanded polymer membrane. Therefore, the degree of densification of the expanded polymer membrane can control the gas permeation across the membrane and be tailored to the required application.

[0039] The polymer may be selected from polytetrafluoroethylene (PTFE), polypropylene (PP), polyethylene (PE), perfluoro(alkyl vinyl ether) ("PAVE" including perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), etc.), vinylidene fluoride (VDF), fluorinated ethylene propylene (FEP), chlorotrifluoroethylene (CTFE), or copolymers or combinations thereof.

[0040] The non-transparent substrate can comprise a metal, for example, aluminum, iron, copper, tin, or alloys or combinations thereof.

[0041] The non-permeable substrate can have a thickness between the first surface and the second surface. The ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 3. The ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 5. The ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 7. The ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 10. The ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 15. The ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 20. The ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 25. Thus, the ratio of the thickness of the non-permeable substrate to the maximum width of the hole or each hole can be at least 3, 5, 7, 10, 15, 20, 25, or any value therebetween.

[0042] The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 3 to 100. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 5 to 100. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 7 to 100. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 10 to 100. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 15 to 100. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 20 to 100. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 25 to 100. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 2 to 90. The ratio of the thickness of the non-transparent substrate to the maximum width of the hole or each hole can be 2 to 80. The ratio of the thickness of the non-permeable substrate to the maximum width of the or each hole can be from 2 to 70. The ratio of the thickness of the non-permeable substrate to the maximum width of the or each hole can be from 2 to 60.

[0043] The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole is at least 0.1 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole is at least 0.5 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole is at least 0.6 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole can be at least 0.7 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole can be at least 0.8 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole can be at least 0.9 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole can be at least 1 / μm.

[0044] The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the hole or each hole may be 0.1 to 1000 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the hole or each hole may be 0.1 to 750 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the hole or each hole may be 0.1 to 500 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the hole or each hole may be 0.1 to 250 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the hole or each hole may be 0.1 to 100 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the hole or each hole may be 0.5 to 1000 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the hole or each hole may be 1 to 1000 / μm. The ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole may be from 2 to 1000 / μm.

[0045] The battery housing may include at least one protective element disposed on at least one of the first and second surfaces of the non-permeable substrate, covering the or each hole. The at least one protective element may prevent particles from entering the or each hole. The at least one protective element may prevent liquid from entering the or each hole. The battery housing may include two protective elements, including a first protective element disposed on the first surface and a second protective element disposed on the second surface, such that the or each hole is covered by both the first and second protective elements. Thus, a first end of the or each hole may be covered by the first protective element, and a second end of the or each hole may be covered by the second protective element.

[0046] At least one protective element may include an aperture material.

[0047] As used herein, the term "open material" refers to a material that has high porosity and low resistance to gas flow. In the context of this embodiment, an open material has a higher CO2 permeability than the housing wall, thereby not restricting CO2 permeability through the or each pore in the non-permeable substrate of the housing wall.

[0048] The at least one protective element can include a highly porous material. The at least one protective element can include a material having a higher CO2 permeability than the housing wall. Thus, the CO2 permeability across the battery housing is not limited by the at least one protective element, but rather by the CO2 permeability of the housing wall. The at least one protective element can have a CO2 permeability of at least 200,000,000 cm3. 3 / (m 2 At least one protective element has a CO2 permeability of at least 300,000,000 cm 3 / (m 2 At least one protective element has a CO2 permeability of at least 400,000,000 cm3 / (m 2 At least one protective element has a CO2 permeability of at least 500,000,000 cm 3 / (m 2 At least one protective element has a CO2 permeability of at least 600,000,000 cm 3 / (m 2 At least one protective element has a CO2 permeability of at least 700,000,000 cm 3 / (m 2 At least one protective element has a CO2 permeability of at least 800,000,000 cm 3 / (m 2 At least one protective element has a CO2 permeability of at least 1,000,000,000 cm 3 / (m 2 At least one protective element may have a CO2 permeability of about 200,000,000 cm 3 / (m 2 10000000000 cm 3 / (m 2 At least one protective element may have a CO2 permeability of about 300,000,000 cm 3 / (m 2 10000000000 cm 3 / (m 2 At least one protective element may have a CO2 permeability of about 400,000,000 cm 3 / (m 2 10000000000 cm 3 / (m 2 At least one protective element may have a CO2 permeability of about 500,000,000 cm 3 / (m 2 10000000000 cm 3 / (m 2At least one protective element may have a CO2 permeability of about 600,000,000 cm 3 / (m 2 10000000000 cm 3 / (m 2 At least one protective element may have a CO2 permeability of about 700,000,000 cm 3 / (m 2 10000000000 cm 3 / (m 2 At least one protective element may have a CO2 permeability of about 800,000,000 cm 3 / (m 2 10000000000 cm 3 / (m 2 ·Sun·Bar).

[0049] At least one protective element can include an expanded polymer. At least one protective element can include expanded polytetrafluoroethylene or expanded polyethylene. At least one protective element can include an expanded polymer that includes a fibrillated microstructure.

[0050] The at least one protective element can include a coating. The coating can be oleophobic. The coating can prevent or inhibit passage of solvent or electrolyte from within the battery housing through the or each hole. The coating can prevent or inhibit wetting of the non-permeable substrate.

[0051] At least one protective element can be less than 200 μm thick. At least one protective element can be less than 150 μm thick. At least one protective element can be less than 100 μm thick. At least one protective element can be less than 50 μm thick. At least one protective element can be less than 40 μm thick. At least one protective element can be less than 30 μm thick.

[0052] The at least one protective element can have a thickness of 1 μm to 200 μm. The at least one protective element can have a thickness of 1 μm to 150 μm. The at least one protective element can have a thickness of 1 μm to 100 μm. The at least one protective element can have a thickness of 1 μm to 50 μm. The at least one protective element can have a thickness of 1 μm to 40 μm. The at least one protective element can have a thickness of 1 μm to 30 μm.

[0053] In some embodiments, the housing wall can be rigid. Thus, the housing wall can be configured to resist deformation, thereby changing the shape of the housing wall. Alternatively, the housing wall can be flexible. Thus, the housing wall can be configured to at least partially deform, thereby changing the shape of the housing wall. For example, the housing wall can be a pouch-type housing wall, and the battery housing can be a battery pouch.

[0054] In some embodiments, the housing wall can include at least one of a metal, a metal alloy, or a combination thereof. In some embodiments, the housing wall can include at least one of iron (Fe), aluminum (Al), or an alloy thereof. In some embodiments, the housing wall can include at least one polymer. The at least one polymer can include a fluoropolymer such as PTFE, PFA, or FEP, or a copolymer thereof. The at least one polymer can include a non-fluoropolymer such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or a copolymer thereof. The housing wall can include a combination of at least one metal layer and at least one polymer layer. The housing wall can include at least one metal layer disposed between at least two polymer layers. Thus, the housing wall can include at least one metal layer, with at least one polymer layer disposed on a first surface of the at least one metal layer and at least one polymer layer disposed on a second surface of the at least one metal layer. This allows the at least one metal layer to be protected by at least one polymer layer on a first surface and at least one polymer layer on a second surface. At least one polymer layer on the first side can be the same as at least one polymer layer on the second side. At least one polymer layer on the first side can comprise the same polymer as at least one polymer layer on the second side. At least one polymer layer on the first side can be different from at least one polymer layer on the second side. At least one polymer layer on the first side can comprise a different polymer than at least one polymer layer on the second side.

[0055] In embodiments where the housing wall comprises multiple layers, the or each hole should be understood to extend through each of the multiple layers to form a through hole through the housing wall.

[0056] In a second aspect, there is provided a venting element comprising a non-permeable substrate, the non-permeable substrate comprising at least one hole, the or each hole extending from a first side of the non-permeable substrate to a second side of the non-permeable substrate.

[0057] The or each hole may have a maximum width of less than 100 μm. The or each hole may have a maximum width of less than 80 μm. The or each hole may have a maximum width of less than 60 μm. The or each hole may have a maximum width of less than 40 μm. The or each hole may have a maximum width of less than 20 μm.

[0058] The hole or each hole may have a maximum width of 0.1 μm to 100 μm. The hole or each hole may have a maximum width of 0.1 μm to 75 μm. The hole or each hole may have a maximum width of 0.1 to 50 μm. The hole or each hole may have a maximum width of 0.1 to 40 μm. The hole or each hole may have a maximum width of 0.1 to 30 μm. The hole or each hole may have a maximum width of 0.1 to 20 μm. The hole or each hole may have a maximum width of 0.1 to 15 μm. The hole or each hole may have a maximum width of 0.1 to 10 μm. The hole or each hole may have a maximum width of 0.1 to 9 μm. The hole or each hole may have a maximum width of 0.1 to 8 μm. The hole or each hole may have a maximum width of 0.1 to 7 μm. The hole or each hole may have a maximum width of 0.1 to 6 μm. The hole or each hole may have a maximum width of 0.1 to 5 μm. The hole or each hole may have a maximum width of 1 to 100 μm. The hole or each hole may have a maximum width of 2 to 100 μm. The hole or each hole may have a maximum width of 3 to 100 μm. The hole or each hole may have a maximum width of 4 to 100 μm. The hole or each hole may have a maximum width of 5 to 100 μm.

[0059] The or each pore may have an effective diameter of less than 100 μm. The or each pore may have an effective diameter of less than 80 μm. The or each pore may have an effective diameter of less than 60 μm. The or each pore may have an effective diameter of less than 40 μm. The or each pore may have an effective diameter of less than 20 μm.

[0060] The hole or each hole may have an effective diameter of 0.1 μm to 100 μm. The hole or each hole may have an effective diameter of 0.1 μm to 75 μm. The hole or each hole may have an effective diameter of 0.1 to 50 μm. The hole or each hole may have an effective diameter of 0.1 to 40 μm. The hole or each hole may have an effective diameter of 0.1 to 30 μm. The hole or each hole may have an effective diameter of 0.1 to 20 μm. The hole or each hole may have an effective diameter of 0.1 to 15 μm. The hole or each hole may have an effective diameter of 0.1 to 10 μm. The hole or each hole may have an effective diameter of 0.1 to 9 μm. The hole or each hole may have an effective diameter of 0.1 to 8 μm. The hole or each hole may have an effective diameter of 0.1 to 7 μm. The hole or each hole may have an effective diameter of 0.1 to 6 μm. The or each hole may have an effective diameter of 0.1 to 5 μm. The or each hole may have an effective diameter of 1 to 100 μm. The or each hole may have an effective diameter of 2 to 100 μm. The or each hole may have an effective diameter of 3 to 100 μm. The or each hole may have an effective diameter of 4 to 100 μm. The or each hole may have an effective diameter of 5 to 100 μm.

[0061] The venting element may include a first protective element disposed on a first side of the non-permeable substrate and capable of blocking the or each hole. The venting element may include a second protective element disposed on a second side of the non-permeable substrate and capable of blocking the or each hole.

[0062] The first and second protective elements may comprise an expanded polymer selected from expanded polytetrafluoroethylene and expanded polyethylene.

[0063] The first protective element and the second protective element may each have a higher CO2 permeability than the or each hole.

[0064] The first protective element and / or the second protective element can include a coating. The coating can be oleophobic. The coating can prevent or inhibit the passage of a solvent or electrolyte through the or each pore. The coating can prevent or inhibit wetting of the non-permeable substrate.

[0065] The vent element can include at least two holes disposed in the non-permeable substrate. The vent element can include at least three holes disposed in the non-permeable substrate. The vent element can include at least four holes disposed in the non-permeable substrate. The vent element can include at least five holes disposed in the non-permeable substrate. The vent element can include at least six holes disposed in the non-permeable substrate. The vent element can include at least seven holes disposed in the non-permeable substrate. The vent element can include at least eight holes disposed in the non-permeable substrate. The vent element can include at least nine holes disposed in the non-permeable substrate. The vent element can include at least ten holes disposed in the non-permeable substrate.

[0066] The vent element may include 1 to 100 holes provided in the non-permeable substrate. The vent element may include 1 to 75 holes provided in the non-permeable substrate. The vent element may include 1 to 50 holes provided in the non-permeable substrate. The vent element may include 1 to 40 holes provided in the non-permeable substrate. The vent element may include 1 to 30 holes provided in the non-permeable substrate. The vent element may include 1 to 20 holes provided in the non-permeable substrate. The vent element may include 1 to 15 holes provided in the non-permeable substrate. The vent element may include 1 to 10 holes provided in the non-permeable substrate.

[0067] The impermeable substrate can comprise a polymer. The polymer can be a fluoropolymer. The polymer can be a non-fluoropolymer. The polymer can be an expanded polymer. The polymer can be a densified expanded polymer.

[0068] For the avoidance of doubt, the term "densified expanded polymeric membrane" refers to a polymeric membrane as defined in the first aspect.

[0069] The polymer may be selected from polytetrafluoroethylene (PTFE), polypropylene (PP), polyethylene (PE), perfluoro(alkyl vinyl ether) ("PAVE" including perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), etc.), vinylidene fluoride (VDF), fluorinated ethylene propylene (FEP), chlorotrifluoroethylene (CTFE), or copolymers or combinations thereof.

[0070] The non-transparent substrate can comprise a metal, for example, aluminum, iron, copper, tin, or alloys or combinations thereof.

[0071] The ventilation element may have a ratio of carbon dioxide (CO2) transmission rate to water vapor (moisture) transmission rate of at least 2, using the test method as described herein.

[0072] The CO2 transmission rate through the ventilation element is at least 25 cm 3 / (day). The CO2 transmission rate through the ventilation element can be at least 50 cm 3 / day. The CO2 transmission rate through the ventilation element can be at least 75 cm 3 / day. The CO2 transmission rate through the ventilation element can be at least 100 cm 3 / day. The CO2 transmission rate through the ventilation element can be at least 150 cm 3 / day. The CO2 transmission rate through the ventilation element can be at least 200 cm 3 / day. The CO2 transmission rate through the ventilation element is 25 cm 3 / day~10,000cm 3 / day. The CO2 transmission rate through the ventilation element is 50 cm 3 / day~10,000cm 3 / day. The CO2 transmission rate through the ventilation element is 75 cm 3 / day~10,000cm 3 / day. The CO2 transmission rate through the ventilation element is 100 cm 3 / day~10,000cm 3 / day. The CO2 transmission rate through the ventilation element can be 150 cm 3 / day~10,000cm 3 / day. The CO2 transmission rate through the ventilation element can be 200 cm 3 / day~10,000cm 3 / day can be.

[0073] It will be appreciated that it is desirable for the water vapor transmission rate through the vent element to be as low as possible. For example, the water vapor transmission rate through the vent element may be less than 200,000 cm 3 / (m 2The water vapor transmission rate through the ventilation element can be less than 150,000 cm 3 / (m 2 The water vapor transmission rate through the ventilation element can be less than 100,000 cm 3 / (m 2 The water vapor transmission rate through the ventilation element can be less than 75,000 cm 3 / (m 2 ·day·bar).

[0074] The vent element can be configured to be installed within an electronic device housing. The vent element can be configured to be installed within a housing wall of a battery housing. The impermeable substrate of the vent element can be part of the impermeable substrate of the housing wall. The impermeable substrate of the vent element can be configured to be inserted into an aperture in the impermeable substrate of the housing wall.

[0075] Thus, the CO2 permeability across the vent element is not limited by the first or second protective element, but rather by the CO2 permeability of the or each pore in the non-permeable substrate.

[0076] For the avoidance of doubt, the features of the non-permeable substrate of the first embodiment are features of the second embodiment. Furthermore, the features of the at least one protective element of the first embodiment are features of the first and second protective elements of the second embodiment.

[0077] According to a third aspect, there is provided a battery comprising a battery housing according to the first aspect.

[0078] The battery can be a secondary battery. The secondary battery can be a lithium ion battery.

[0079] As used herein, the term "lithium ion battery" refers to any battery configured so that lithium ions migrate between a negative electrode and a positive electrode during operation of the battery. Examples of lithium ion batteries include, but are not limited to, lithium ion polymer (LiPo) batteries, lithium sulfur (Li-S) batteries, and thin-film lithium batteries.

[0080] The positive electrode can be selected from lithium nickel manganese cobalt oxide ("NMC"), lithium nickel cobalt aluminum oxide ("NCA"), lithium manganese oxide ("LMO"), lithium iron phosphate ("LFP"), lithium cobalt oxide ("LCO"), or any combination thereof.

[0081] The negative electrode can be selected from lithium, graphite, lithium titanate ("LTO"), tin-cobalt alloy, or any combination thereof.

[0082] In some embodiments, the battery can include at least one separator, which can include at least one material selected from polypropylene, polyethylene, at least one tetrafluoroethylene (TFE) polymer or copolymer, at least one vinylidene fluoride homopolymer, at least one hexafluoropropylene (HFP)-vinylidene fluoride copolymer, or any combination thereof.

[0083] The electrolyte is an electrolytic solution, and the electrolytic solution can include at least one solvent and at least one electrolyte salt. The at least one solvent of the electrolytic solution can include at least one organic solvent. The at least one organic solvent of the electrolyte can be selected from propylene carbonate, ethylene carbonate, diethyl carbonate (DEC), dimethyl carbonate (DMC), or a mixture thereof.

[0084] The electrolyte includes at least one additive, and the at least one additive can be configured to release at least one gas selected from CO, H, CO, CH, or any combination thereof during operation of the battery. The at least one additive can be selected from the group including vinylene carbonate (VC), ethylene sulfite (ES), and fluoroethylene carbonate (FEC).

[0085] The electrolyte may release at least one gas during use of the battery. The at least one gas may be a decomposition product of the electrolyte.

[0086] The electrolyte may be impregnated within at least one separator.

[0087] The housing wall of the battery housing may include an aperture and a vent element according to the second aspect disposed within said aperture.

[0088] It should be understood that the features of the battery housing of the first embodiment are also features of the battery housing of the third embodiment. [Brief explanation of the drawings]

[0089] BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of non-limiting example, with reference to the accompanying drawings, in which:

[0090] [Figure 1] FIG. 1 is a cross-sectional side view of a portion of a battery housing according to an embodiment.

[0091] [Figure 2] FIG. 2 is a cross-sectional side view of a portion of a battery housing according to an embodiment.

[0092] [Figure 3] Figure 3 shows the test equipment for measuring CO2 permeability / transmission rate.

[0093] [Figure 4] Figure 4 shows the test equipment for measuring moisture permeability / transmission rate.

[0094] [Figure 5] Figure 5 is an SEM image of an example of a hole with a maximum width of 5.3 μm in an aluminum substrate.

[0095] [Figure 6] FIG. 6 is an SEM image of an example of pores with a maximum width of 4.1 μm in a densified expanded polytetrafluoroethylene (ePTFE) substrate.

[0096] [Figure 7] FIG. 7 is a cross-sectional side view of a vent element according to an embodiment.

[0097] [Figure 8] FIG. 8 is a cross-sectional side view of a battery housing including a vent element according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0098] Detailed Description While the following provides detailed descriptions of making and using various embodiments of the invention, it should be understood that the present invention provides many applicable inventive concepts that can be implemented in a variety of specific contexts. The specific embodiments described herein are merely illustrative of specific examples of how to make and use the invention and do not limit the scope of the invention.

[0099] To facilitate understanding of the present invention, several terms are defined below. Terms defined herein have meanings commonly understood by one of ordinary skill in the art relevant to the present invention. Terms such as "a," "an," and "the" do not refer to a single entity only, but include general classes that may be described with specific examples. While terms herein are used to describe specific embodiments of the present invention, their use does not limit the present invention, except as outlined in the claims.

[0100] Test Method CO2 transmittance The CO2 permeability through the substrate was measured according to ASTM D1434-82 (Standard Test Method for Measuring Gas Permeation Properties of Plastic Films and Sheeting). A differential pressure test method was used. The test apparatus is shown in Figure 3.

[0101] CO2 permeability of 3,000,000 cm 3 / (m 2 For samples with relatively low permeability (less than 1 / 2 sq. m / s), the gas permeability of the substrate was measured using a Labthink® gas permeability tester (model VAC-V2). The sample substrate was placed 5 cm apart from the center. 2 The mask was placed in an aluminum mask holder (Mocon part number 052-612) with an opening of 1.5 mm. The mask was secured in the test cell of the instrument and sealed in the chamber. A vacuum was applied for 25 minutes to remove air from the test chamber. Dry CO2 gas was then introduced into the chamber on the first side of the substrate. A differential pressure of 1 bar was adjusted across the substrate for the measurement. The CO2 passing through the sample substrate and into the second side of the substrate was detected and the permeability of the substrate was calculated. The test temperature was set to 37.8°C. The proportionality coefficient was set to 10%. The CO2 permeability was measured by the instrument in cm 3 / (m 2 The values ​​are reported in units of (days) and converted to volumetric values ​​at standard temperature and pressure (0°C, 1 bar).

[0102] CO2 permeability of 3,000,000 cm 3 / (m 2 For samples with relatively high permeability (> 1000 kJ / day, bar), the gas permeability of the substrate was measured using a Shimadzu GC-2014 gas chromatograph, GTR Tec Corporation, Japan, GTR series gas permeability analyzer (model number GTR-30XAGR). The sample substrate was measured by measuring the gas permeability of the substrate with a 5 cm diameter at the center. 2The mask was placed in an aluminum mask holder (Mocon part number 052-612) with an opening of 1.5 mm. The mask was then cut to approximately 6 x 6 cm. It was then secured in the test cell of the instrument and sealed within the chamber. A vacuum was applied for 10 minutes to remove air from the test chamber. Dry CO2 gas was then introduced into the chamber from the first side of the substrate. For the measurement, a differential pressure of 1 bar was adjusted across the substrate. CO2 passing through the sample substrate and flowing to the second side of the substrate was detected, and the permeability of the substrate was calculated. The test temperature was set to 37.8°C. The analyte collection time was set to 5-10 seconds, and the GC analysis time was set to 3 minutes. CO2 permeability was measured in cm by the instrument. 3 / (m 2 This is reported in units of cm 3 / (m 2 ⋅day ⋅bar), where the volume values ​​are at standard temperature and pressure as defined above.

[0103] Moisture permeability The water vapor transmission rate of the substrates was determined in accordance with ASTM F1249-20 (Standard Test Method for Water Vapor Transmission Rate of Plastic Films and Sheeting Using a Modulated Infrared Sensor). The isobaric method was used. The test equipment is shown in Figure 4. Specifically, an AMETEK / Mocon water vapor transmission analyzer (Model: Permatran-W 3 / 34) was used to test the water vapor transmission rate of the materials. The sample substrates were placed on a 5 cm center. 2The mask was placed in an aluminum mask holder (Mocon, part number 052-612) with an opening of 1.5 mm. The mask was then secured to the instrument's test cell and sealed within the chamber. The sample substrate was positioned to divide the sample chamber into a first section (high humidity chamber) and a second section (low humidity chamber). The first section held moisture and formed the high humidity side of the sample substrate. Dry nitrogen gas was vented into the second section, forming the low humidity side of the sample substrate. Both the first and second sections of the chamber were maintained at ambient pressure. Testing was performed at 100% relative humidity and 37.8°C on the high humidity side. The amount of water vapor passing through the sample substrate was measured by detecting water vapor passing from the first side of the substrate on the high humidity side through the sample substrate to the second side of the substrate on the low humidity side at the "dry gas" outlet. The water vapor transmission rate was measured by the instrument in g / (m 2 Reported in units of (days).

[0104] The water vapor transmission rate was calculated by dividing the water vapor partial pressure difference (0.066 bar) using the ideal gas law to obtain cm 3 / (m 2 The carbon dioxide (CO2) permeability and water vapor (moisture) permeability (unit: cm) were calculated. 3 / (m 2 The ratio of CO2 permeability to water vapor (moisture) permeability was calculated by converting the CO2 permeability to the volume at standard temperature and pressure as defined above using the unit (units per square meter). The ratio of CO2 permeability to water vapor permeability is unitless (i.e., dimensionless).

[0105] Physical parameters Image analysis is used to calculate the surface area of ​​the holes from the SEM images. The effective diameter of the holes is calculated from the measured area of ​​the holes on the laser exit side. Image analysis is used to estimate the maximum width of the holes from the SEM images.

[0106] The substrate thickness of the polymer film was measured using a Mitutoyo Lightmatic VL50S thickness gauge, and the substrate thickness of the aluminum foil was measured using a Mitutoyo 547-400S Digimatic thickness gauge.

[0107] Referring to FIG. 1, battery housing 1 includes a housing wall 2, three holes 4 formed in housing wall 2, a first protective layer 6 (acting as at least one protective element), and a second protective layer 8 (acting as at least one further protective element).

[0108] The housing wall 2 comprises aluminum (Al) foil having a thickness of 29.3 μm, and three holes 4 extend through the housing wall 2 from the first surface 10 to the second surface 12. The three holes 4 have a generally circular cross-section and a diameter (corresponding to their widest point) of 4 μm. The first protective layer 6 and the second protective layer 8 comprise expanded polytetrafluoroethylene (ePTFE). The first protective layer 6 is disposed on the first surface 10, and the second protective layer 8 is disposed on the second surface 12. The first protective layer 6 and the second protective layer 8 cover the three holes 4 to prevent particles from entering or blocking one or more of the three holes 4 and to allow the three holes 4 to vent gases that may be generated within the battery housing 1.

[0109] 2, battery pouch 20 (acting as a battery housing) includes pouch wall 22 (acting as a housing wall) and one hole 24 formed in pouch wall 22. Pouch wall 22 is 100 μm thick and includes aluminum foil 26, a polyethylene terephthalate (PET) layer 28 facing the outside of the battery pouch, and a polypropylene layer 30 facing the inside of the battery pouch. Aluminum foil 26 is disposed between polyethylene terephthalate layer 28 and polypropylene layer 30. One hole 24 has a generally oval cross section and a maximum width of 12 μm.

[0110] In an alternative embodiment to that shown in Figure 2, first and second protective layers are provided over holes 24 to prevent holes 24 from becoming blocked, for example by particles. The first and second protective layers comprise expanded ultra-high molecular weight polyethylene.

[0111] 7, vent element 100 includes a densified ePTFE substrate 102 (acting as a non-permeable substrate), a first ePTFE membrane 104 (acting as a first protective element), and a second ePTFE membrane 106 (acting as a second protective element). A single 5 μm hole 108 was drilled in substrate 102. Substrate 102 was 25 μm thick. First ePTFE membrane 104 and second ePTFE membrane 106 filled hole 108 on a first side 110 of substrate 102 and a second side 112 of substrate 102, respectively.

[0112] Referring to FIG. 8, the vent element 100 was installed over the aperture 114 of the battery housing 116 . [Example]

[0113] example Specific examples are shown in Table 1, and the measurement performance of these examples is shown in Table 2.

[0114] The PTFE substrate material used in Examples 1 and 2 below was prepared using the following method.

[0115] PTFE resin was mixed with a lubricant (Isopar K, Exxon, Houston, TX) at a concentration of 0.167 g / g, then blended and pressed into cylindrical pellets and heat-conditioned at a temperature of 70°C for 24 hours. The cylindrical pellets were then extruded through a rectangular die with a reduction ratio of 88 to form a tape with a thickness of 0.711 mm. The resulting tape was then dried to remove the lubricant.

[0116] The dried PTFE tape was stretched between heated drums at a linear speed of about 46% / sec, a drum temperature of 315°C, and an elongation of 1,032% in the y direction. The tape was then stretched in the x direction at a linear speed of about 56% / sec, a temperature of about 300°C, and an elongation of 2,863%. The resulting product had a density of about 0.20 g / cm. 3 The unsintered expanded PTFE membrane was

[0117] The resulting unsintered expanded PTFE membrane was compressed and densified at a temperature of 370° C. and a pressure of 1724 kPa (250 psi) according to the teachings of U.S. Patent No. 5,374,473 and U.S. Patent No. 7,521,010 (B2). The resulting product was a sintered and densified ePTFE film approximately 24 μm thick.

[0118] [Table 1]

[0119] In Examples 2, 4, 6, 7-14, 16, and 17 above, the holes were formed by laser drilling, and the exit effective hole size referenced in Table 1 above refers to the side of the substrate opposite to the side on which the laser was applied to form the hole (i.e., the side from which the laser "exits" the substrate). In Example 15, the hole was formed by mechanical drilling using a 50 μm drill bit.

[0120] 50 μm thick PCTFE film was obtained from Honeywell (Hydroblock P2000TRl). 500 μm thick polypropylene film was obtained from McMaster-Carr (part number 5895N112). 25 μm and 50 μm thick aluminum foil was obtained from Grainger (part numbers 4UGH8 and 4UGJ1). 100 μm aluminum foil was obtained from McMaster-Carr (part number 9708K54). 400 μm aluminum sheet (6061-T6) was obtained from Xometry Supplies (nominal thickness as received from manufacturer).

[0121] PP-Al-nylon-PET composite film is a standard material for pouch-type battery housings. It was obtained from Dai Nippon Printing Co., Ltd. (part number D-EL408PH). Its total thickness is 153 μm, and it contains aluminum (approximately 40 μm), polypropylene (approximately 80 μm), PET (approximately 12 μm), and nylon (approximately 15 μm).

[0122] [Table 2] TR = Permeability calculated for a gas volume at standard temperature and pressure as defined herein

[0123] As noted above, embodiments including holes having a maximum width of at least 4 μm exhibit a much higher CO2 permeability through the substrate forming the battery housing compared to embodiments that do not include holes, resulting in a surprisingly improved selectivity of CO2 permeability relative to water vapor permeability.

[0124] While the foregoing describes approved embodiments of the present invention, it will be readily understood that various changes and modifications in shape, design, construction and arrangement of parts of other embodiments may be made without departing from the present invention, and all such changes and modifications are contemplated as embodiments that are part of the present invention as defined in the appended claims.

Claims

1. a housing wall, the housing wall comprising a non-permeable substrate and at least one hole disposed in the non-permeable substrate, the or each hole extending from a first side of the non-permeable substrate to a second side of the non-permeable substrate, the or each hole having a maximum width of 0.1 μm to 100 μm, the housing wall having a maximum transmittance of carbon dioxide (CO ２ ) a ratio of water vapor (moisture) permeability to water vapor (moisture) permeability of at least 2.

2. The battery housing of claim 1 , wherein said battery housing defines an enclosed space, said enclosed space holding an electrolyte.

3. CO passing through the housing wall ２ Transmittance is at least 25 cm ３ 3. The battery housing according to claim 1, wherein the temperature is 100°C / (day).

4. The housing wall is ２ The battery housing of any one of claims 1 to 3, wherein the ratio of the permeability to the moisture permeability is at least 3.

5. 5. The battery housing of claim 1, wherein the non-permeable substrate has a thickness between the first surface and the second surface, and wherein the ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole is at least 0.1 / μm.

6. A battery housing according to any preceding claim, wherein the or each hole has a maximum width of from 1 μm to 10 μm.

7. A battery housing according to any preceding claim, wherein the or each hole has an effective diameter of from 0.1 μm to 100 μm.

8. 8. The battery housing of claim 1, wherein the battery housing includes at least one protective element provided on at least one of the first and second major surfaces of the non-permeable substrate and covering the or each hole.

9. The battery housing of claim 8 , wherein the battery housing includes two protective elements.

10. 10. The battery housing of claim 9, wherein the two protective elements include a first protective element provided on the first major surface and a second protective element provided on the second major surface, whereby the or each hole is covered by the first protective element and the second protective element.

11. The at least one protective element has a higher CO ２ The battery housing according to any one of claims 8 to 10, comprising a material having permeability.

12. The battery housing of any one of claims 8 to 11, wherein the at least one protective element comprises an expanding polymer.

13. The battery housing of claim 12 , wherein the at least one protective element comprises expanded polytetrafluoroethylene or expanded polyethylene.

14. 1. A venting element comprising: a non-permeable substrate; a first protective element; and a second protective element, wherein the non-permeable substrate comprises at least one hole, the or each hole extending from a first surface of the non-permeable substrate to a second surface of the non-permeable substrate, the or each hole having a maximum width of 0.1 μm to 100 μm, the first protective element being disposed on the first surface of the non-permeable substrate and blocking the or each hole, and the second protective element being disposed on the second surface of the non-permeable substrate and blocking the or each hole.

15. The ventilation element is configured to vent carbon dioxide (CO ２ 15. The venting element of claim 14, wherein the ratio of the permeability to the water vapor (moisture) permeability is at least 2 using the test method described herein.

16. 16. A ventilation element according to claim 14 or claim 15, wherein the first protective element and the second protective element comprise an expanded polymer selected from expanded polytetrafluoroethylene and expanded polyethylene.

17. Each of the first and second protective elements has a higher CO 2 concentration than the or each hole. ２ The ventilation element according to any one of claims 14 to 16, which has permeability.

18. 18. A venting element according to any one of claims 14 to 17, wherein the non-permeable substrate has a thickness between the first side and the second side, and wherein the ratio of the thickness of the non-permeable substrate to the cross-sectional area of ​​the or each hole is at least 0.1 / μm.

19. A venting element according to any one of claims 14 to 18, wherein the or each hole has a maximum width of from 1 μm to 10 μm.

20. A venting element according to any one of claims 14 to 19, wherein the or each hole has an effective diameter of from 0.1 μm to 100 μm.

21. CO passing through the vent element ２ Transmittance is at least 25 cm ３ The ventilation element according to any one of claims 14 to 20, wherein the saturation temperature is 100°C / (day).

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