Patent Description:
With the advantages of high energy density, high power density, high recyclability, long storage time, etc., the rechargeable battery cell is widely used in electric vehicles. Since the exhaust safety of the battery cell restricts its development, the technical research related to the safety performance of the battery cell has been conducted.

<CIT> relates to a gas permeable member including a gas permeable sheet configured to allow a gas to permeate therethrough; and a holder configured to hold the gas permeable sheet, wherein the gas permeable member is mounted in a container body having a surface on which a through hole communicating with an internal space is open by being inserted through the opening, so as to allow the gas to permeate therethrough between the internal space and the outer space of the container body via the gas permeable sheet, and the gas permeable member further includes a pressing part that contacts with an inner wall of the through hole and that presses the inner wall toward the open side at the contact position when a force is applied in a pull-out direction from the open side.

<CIT> relates to a cover for gas permeable container which is mounted on a container body having an internal space and an opening communicating with the internal space includes: a closing part configured to close the opening; and a gas permeable part configured to be permeable to a gas, thereby allowing the gas to flow between the internal space and an outer space of the container body, wherein the gas permeable part is constituted by a gas permeable member having a gas permeable sheet, and the gas permeable member is integrally formed with a material constituting the closing part.

Embodiments of the application provide a cover assembly, a battery cell, a battery, an electric device, a method and an apparatus. The cover assembly may meet a release requirement of gas in the battery cell, and also may guarantee safety performance of the battery cell. In accordance with the present invention, there is provided a cover assembly as set out in claim <NUM>, a battery cell as set out in claim <NUM>, a battery as set out in claim <NUM> and an electric device as set out in claim <NUM>.

In one aspect, an embodiment of the application provides a cover assembly of a battery cell. The cover assembly includes: a cover plate, a fixing member, a breathable film and a support, the cover plate being provided with a first through hole, the fixing member being used for being connected to the cover plate and provided with a second through hole, where the second through hole is configured to be in gas communication with the first through hole, the breathable film being connected to the fixing member and used for covering the second through hole, the second through hole being filled with the support, and the support being connected to the fixing member and used for supporting the breathable film and allowing gas passing through the breathable film to pass through.

According to the cover assembly provided by the embodiment of the application, the cover assembly includes the cover plate, the fixing member, the breathable film and the support, where the second through hole is in gas communication with the first through hole, the breathable film has a breathable function, accordingly, gas generated by the battery cell may be discharged to an outside of the battery cell by means of the breathable film, and the gas is prevented from being accumulated in a casing, thereby improving performance of an electrode assembly and prolonging service life of the battery cell. By arranging the support, the breathable film may be supported, it may be guaranteed that the breathable film is still kept intact under the condition of large internal pressure of the battery cell, damage to the breathable film may be avoided, breathable performance of the breathable film in the entire service life of the battery cell may be guaranteed, and further the safety performance of the battery cell may be guaranteed.

According to one aspect of an embodiment of the application, a melting point of the support is greater than that of the breathable film. When a temperature of the battery cell reaches the melting point of the breathable film, the breathable film deforms and flows, since the melting point of the support is greater than that of the breathable film, a material of the support does not reach the melting point thereof, a support framework effect may be achieved on the breathable film, and flowing and deformation of the breathable film are reduced.

According to one aspect of an embodiment of the application, a difference between the melting point of the support and the melting point of the breathable film is greater than or equal to <NUM>, so the support may be effectively prevented from deforming when the breathable film deforms and flows, thereby guaranteeing a support effect on the breathable film.

According to one aspect of an embodiment of the application, a shear strength at a joint between the support and the fixing member is greater than or equal to <NUM> MPa. When internal pressure of the battery cell is increased, shape stability of the support and stability of connection strength between the support and the fixing member may be guaranteed, thereby guaranteeing the support effect on the breathable film, preventing the breathable film from deforming or even breaking, and guaranteeing the breathable effect of the breathable film.

According to one aspect of an embodiment of the application, the breathability of the support is greater than that of the breathable film. Since the breathable film is made of a material for controlling the entire breathable effect of the battery, gas passing through the breathable film needs to be smoothly discharged from the support to the outside of the battery cell. The breathability of the support is greater than that of the breathable film, so the gas, passing through the breathable film, in the battery cell may be smoothly discharged from the support, so as to guarantee the safety performance of the battery cell.

According to one aspect of an embodiment of the application, the fixing member is a metal ring provided with the second through hole, the support includes a hydrophobic breathable material, and the support is connected to the fixing member by means of a chemical bond or a metal bond. By means of the above arrangement, on the basis of meeting a support requirement for the breathable film, it may be guaranteed that gas passing through the breathable film may smoothly pass through the support, so as to guarantee the breathable effect of the breathable film, water vapor, etc. may be blocked, so as to avoided the situation that the water vapor enters the battery cell to affect the battery cell, in addition, electrolyte in the battery cell may be prevented from being exposed, and the connection strength between the support and the fixing member may be guaranteed.

According to one aspect of an embodiment of the application, a difference between a maximum size of the breathable film and a maximum size of the support is greater than or equal to <NUM> in a radial direction of the first through hole, and an orthographic projection of a geometric center of the breathable film coincides with an orthographic projection of a geometric center of the support in an axial direction of the first through hole. A combination area between a periphery of the breathable film and the support may be guaranteed, and composite strength and sealing performance between the breathable film and the support may be guaranteed.

According to one aspect of an embodiment of the application, a hole diameter of the second through hole remains unchanged in a direction away from the breathable film.

According to one aspect of an embodiment of the application, a hole diameter of at least part, in a length direction, of the second through hole is gradually reduced in a direction away from the breathable film. When the cover assembly is used for the battery cell, one side of the breathable film faces a battery assembly and makes direct contact with the gas inside the battery cell. The hole diameter of at least part, in the length direction, of the second through hole is gradually reduced in the direction away from the breathable film, so when the breathable film deforms outwards in advance under the action of the internal gas pressure of the battery cell, a hole wall of the second through hole formed in an enclosing mode may provide certain support for the breathable film at a hole diameter reducing position, so as to avoid deformation of the breathable film, thereby guaranteeing the breathable effect and the safety performance of the breathable film.

According to one aspect of an embodiment of the application, the hole diameter of the second through hole is gradually reduced in the direction away from the breathable film.

According to one aspect of an embodiment of the application, the hole diameter of the second through hole is reduced section by section in the direction away from the breathable film.

According to one aspect of an embodiment of the application, the hole diameter of the second through hole is firstly reduced and then increased in the direction away from the breathable film.

According to one aspect of an embodiment of the application, the first through hole includes an accommodation section and an extension section extending from the accommodation section, a hole diameter of the accommodation section being greater than that of the extension section, and the fixing member and the support are at least partially accommodated in the accommodation section. Thus, space occupied by the fixing member is reduced, so as to reduce an overall height of the battery cell.

The accommodation section is provided with a bottom wall surrounding the extension section, the breathable film is at least partially sandwiched between the fixing member and the bottom wall to separate the second through hole from the extension section, and the support is arranged on one side, away from the extension section, of the breathable film. The accommodation section and the extension section with different hole diameters form a step surface (that is, the bottom wall), and the step surface may support the fixing member, so the fixing member may be conveniently positioned when the fixing member and the cover plate are welded.

According to one aspect of an embodiment of the application, the fixing member is provided with a groove arranged around the second through hole, and the breathable film is at least partially accommodated in the groove. By arranging the groove, the space occupied by the breathable film may be reduced, and the overall thickness of the fixing member and the breathable film may be reduced.

In another aspect, an embodiment of the application provides a battery cell, including: a casing provided with an opening; an electrode assembly accommodated in the casing; and the above cover assembly, wherein the cover assembly is connected to the casing and covers the opening of the casing, a breathable film is positioned between the electrode assembly and a support.

The battery cell provided in the embodiment of the application includes the cover assembly provided in each embodiment, gas generated in the battery cell may be discharged to the outside of the battery cell by means of the breathable film, and the gas is prevented from being accumulated in the casing, thereby improving performance of the electrode assembly and prolonging the service life. By arranging the support in the cover assembly, the breathable film may be supported, it may be guaranteed that the breathable film is still kept intact under the condition of large internal pressure of the battery cell, damage to the breathable film may be avoided, breathable performance of the breathable film in the entire service life of the battery cell may be guaranteed, and further better safety performance of the battery cell is achieved.

In yet another aspect, an embodiment of the application provides a battery, including the battery cell described above.

In yet another aspect, an embodiment of the application provides an electric device, including the battery described above, and the battery is used for providing electrical energy.

In yet another aspect, which does not form part of the invention, an embodiment of the application provides a method for manufacturing a battery cell, including:.

In yet another aspect, which does not form part of the invention, an embodiment of the application provides an apparatus for manufacturing a battery cell, the apparatus including:.

In order to describe the technical solutions in the embodiments of the application more clearly, the accompanying drawings required for describing the embodiments are briefly described below. Obviously, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and a person of ordinary skill in the art would also be able to derive other accompanying drawings from these accompanying drawings without creative efforts.

In the drawings, the components are not drawn to actual scale.

Brief Description of the Numbers:
<NUM>-vehicle; 1a-motor; 1b-controller; <NUM>-battery; <NUM>-first shell; <NUM>-second shell; <NUM>-battery module; <NUM>-battery cell; <NUM>-casing; <NUM>-electrode assembly; <NUM>-cover assembly; <NUM>-cover plate; <NUM>-fixing member; <NUM>-breathable film; <NUM>-support; <NUM>-electrode terminal; <NUM>-rupture disc; <NUM>-first through hole; 337a-accommodation section; 337b-extension section; 337c-bottom wall; <NUM>-second through hole; <NUM>-groove; <NUM>-apparatus; <NUM>-first assembling device; <NUM>-second assembling device; and <NUM>-third assembling device.

The implementation of the application will be further described in detail with reference to the accompanying drawings and the embodiments. The following detailed description of the embodiments and the accompanying drawings serve to illustrate principles of the application as examples, but are not intended to limit the scope of the application, that is, the application is not limited to the described embodiments.

In the description of the application, the following is to be noted: unless otherwise specified, "plurality" means two or more; the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate azimuthal or positional relations only for ease of description of the application and for simplicity of description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation and be constructed and operative in a particular orientation, and thus may not be construed as a limitation on the application. Moreover, the terms "first", "second", "third", etc. are merely for descriptions and may not be understood as indication or implication of relative importance. "Perpendicular" is not perpendicular in a strict sense, but within error allowance. "Parallel" is not parallel in a strict sense, but within error allowance.

Nouns of locality appearing in the following description are orientation shown in the drawings and are not intended to limit the specific structure of the application. In the description of the application, it is also noted that unless expressly specified otherwise, the terms "mount", "connect", "connected", etc. are to be construed broadly and, for example, may be fixedly connected, or detachably connected, or integrally connected, and may be direct connected or indirect connected via an intermediary medium. The specific meanings of the above terms in the application may be understood on a case-by-case basis for those with ordinary skills in the art.

The applicant has investigated and analyzed a cover assembly after it has been found that the cover assembly with a breathable film is prone to the problem of breakage of the breathable film during operation. The applicant discovers that as the breathable film used in the cover assembly is very thin and has the problems of low strength, easiness in deformation, etc., the number of nanopores or micropores in the breathable film is increased and the pore diameter is increased when the breathable film is stretched to generate plastic deformation, and then the breathability is increased. When the outward breathability amount of gas in the battery cell is increased, external excessive water vapor permeates into the battery cell, so risks are brought to the electrical performance (for example, service life, direct current resistance (DCR), etc.) and safety performance of the battery cell. Moreover, when the internal pressure of the battery cell is increased, the breathable film has risk of rupture, which may cause a series of failure conditions caused by liquid leakage of the battery cell.

Based on the above problems discovered by the applicant, the applicant has made improvements to the structure of the battery cell. An embodiment of the application is further described below.

For a better understanding of the application, embodiments of the application are described below in conjunction with <FIG>.

With reference to <FIG>, this embodiment of the application provides an electric device using a battery <NUM> as a power supply. The electric device may be, but is not limited to, a vehicle, a ship, an aircraft, etc. One embodiment of the application provides a vehicle <NUM>. The vehicle <NUM> may be a fuel, gas or new energy vehicle. The new energy vehicle may be a battery electric vehicle, a hybrid electric vehicle, an extended-range vehicle, etc. In one embodiment of the application, the vehicle <NUM> may include a motor 1a, a controller 1b, and the battery <NUM>, where the controller 1b is used for controlling the battery <NUM> to supply power to the motor 1a; the motor 1a is connected to wheels by means of a transmission mechanism, thereby driving the vehicle <NUM> to travel; and the battery <NUM> may be used as a driving power source for the vehicle <NUM> to provide driving power for the vehicle <NUM> instead of or partially instead of fuel or natural gas. In one example, the battery <NUM> may be arranged at a bottom, head or tail of the vehicle <NUM>. The battery <NUM> may be used to power the vehicle <NUM>. In one example, the battery <NUM> may be used as an operational power source of the vehicle <NUM> for a circuit system of the vehicle <NUM>. Illustratively, the battery <NUM> may be used for meeting work power demand at startup, navigation, and operation of the vehicle <NUM>.

With reference to <FIG>, the battery <NUM> may include two or more battery modules <NUM>. In some optional embodiments, the battery <NUM> further includes a box. The battery module <NUM> is arranged in the box. The two or more battery modules <NUM> are arranged in the box. The type of the box is not limited. The box may be a frame-like box, a disc-like box, a cabinet-like box, etc. Illustratively, the box includes a first shell <NUM> for accommodating the battery module <NUM> and a second shell <NUM> covering the first shell <NUM>. The first shell <NUM> covers the second shell <NUM> to define an accommodation portion for accommodating the battery module <NUM>. In some embodiments, the battery <NUM> may also include one battery module <NUM>. In other optional embodiments, the battery <NUM> includes a box and a plurality of battery cells arranged in the box directly.

With reference to <FIG>, for meeting different power use requirements, the battery module <NUM> may include one or more battery cells <NUM>. The plurality of battery cells <NUM> may be connected in series, in parallel or in a series-parallel mode to form a battery module <NUM>, and then the plurality of battery modules <NUM> may be connected in series, in parallel or in a series-parallel mode to form a battery. A series-parallel mode refers to a mixture of series connection and parallel connection. Illustratively, the battery <NUM> may include the plurality of battery cells <NUM>, where the plurality of battery cells <NUM> may be connected in series, in parallel or in series-parallel. The plurality of battery cells <NUM> may be arranged in the box directly. That is, the plurality of battery cells <NUM> may form the battery <NUM> directly, or may form the battery module <NUM> first, and then the battery module <NUM> forms the battery <NUM>. The battery cell <NUM> includes, but is not limited to, a lithium-ion battery cell, a lithium-ion primary battery, a lithium-sulfur battery, a sodium lithium-ion battery, or a magnesium ion battery.

When the battery cell <NUM> of the embodiment of the application is used in the vehicle <NUM>, a width of the battery cell <NUM> equals a height of the vehicle <NUM>. The width of the battery cell <NUM> is also strictly limited by space limitation in a height direction of the vehicle <NUM>, so when capacity of the battery cell <NUM> needs to be increased, the width of the battery cell <NUM> may not be infinitely increased, and a length of the battery cell <NUM> may be increased.

With reference to <FIG>, the battery cell in the embodiment of the application includes a casing <NUM> and an electrode assembly <NUM> arranged in the casing <NUM>. The casing <NUM> of the embodiment of the application is of a square structure or other shapes. The casing <NUM> has an internal space accommodating the electrode assembly <NUM> and electrolyte, and an opening in communication with the internal space. The casing <NUM> may be made of aluminum, an aluminum alloy, plastic, etc. The electrode assembly <NUM> is a core member for the battery cell <NUM> to charge and discharge.

The electrode assembly of the embodiment of the application may be formed by stacking or winding a first pole piece, a second pole piece and a diaphragm between the first pole piece and the second pole piece together, and the diaphragm is an insulator between the first pole piece and the second pole piece. In this embodiment, illustratively, the first pole piece is a positive pole piece, and the second pole piece is a negative pole piece. Each of the positive pole piece and the negative pole piece includes a coated area and an uncoated area, the coated area of the positive pole piece is coated with a positive pole piece active substance, and the coated area of the negative pole piece is coated with a negative pole piece active substance. On the coated area, the active substance coats a current collector formed of thin metal foil, and no active substance coats the uncoated area. The electrode assembly <NUM> also includes two tabs, that is, a positive tab and a negative tab. The coated area of the positive pole piece and the coated area of the negative pole piece form a body portion. The uncoated area of the positive pole piece is staked to form the positive tab, and the uncoated area of the negative pole piece is stacked to form the negative tab. In some embodiments, the body portion is provided with two end faces oppositely arranged in a height direction, and the positive tab and the negative tab may extend from one end face of the body portion respectively.

The battery cell <NUM> of the embodiment of the application further includes a cover assembly <NUM>. The cover assembly <NUM> is connected to the casing <NUM> and seals the opening of the casing <NUM>. Illustratively, the cover assembly <NUM> and the casing <NUM> may be connected by means of welding.

With reference to <FIG>, the cover assembly <NUM> provided in the embodiment of the application includes a cover plate <NUM>, a fixing member <NUM>, a breathable film <NUM> and a support <NUM>, where the cover plate <NUM> is provided with a first through hole <NUM>. The fixing member <NUM> is used for being connected to the cover plate <NUM> and provided with a second through hole <NUM>, where the second through hole <NUM> is configured to be in gas communication with the first through hole <NUM>. The breathable film <NUM> is connected to the fixing member <NUM>, where the breathable film <NUM> is used for covering the second through hole <NUM>. The second through hole <NUM> is filled with the support <NUM>, and the support <NUM> is connected to the fixing member <NUM> and used for supporting the breathable film <NUM> and allowing gas passing through the breathable film <NUM> to pass through.

Since gas (for example, CO, CO2, CH4, C2H6, H2, etc.) is generated in a charging/discharging process of the electrode assembly <NUM>, internal pressure in the casing <NUM> is continuously increased along with the accumulation of the gas, which is likely to cause the risk of battery deformation and deterioration of performance of the electrode assembly <NUM>. In the battery cell <NUM> according to a first illustrative embodiment, the second through hole <NUM> is in gas communication with the first through hole <NUM>, the breathable film <NUM> has a breathable function, accordingly, the generated gas is discharged to an outside of the battery cell <NUM> by means of the first through hole <NUM>, the breathable film <NUM> and the second through hole <NUM>, and the gas is prevented from being accumulated in the casing <NUM>, thereby improving performance of the electrode assembly <NUM> and prolonging service life of the battery cell <NUM>.

By arranging the support <NUM>, the breathable film <NUM> is supported, it is guaranteed that the breathable film <NUM> is still kept intact under the condition of large internal pressure of the battery cell <NUM>, damage to the breathable film <NUM> is avoided, breathable performance of the breathable film <NUM> in the entire service life of the battery cell <NUM> is guaranteed, and further the safety performance of the battery cell <NUM> is guaranteed.

Optionally, the cover assembly <NUM> further includes an electrode terminal <NUM> arranged on the cover plate <NUM>, the electrode terminal <NUM> extending outside the cover plate <NUM> and being electrically connected to the positive and negative pole pieces separately, and the electrode terminal <NUM> may be circular or square in shape, without limitation. Two or more battery cells <NUM> may be connected in series, in parallel, or in a series-parallel mode by means of the respective electrode terminals <NUM>.

Optionally, the cover plate <NUM> is formed as a sheet metal, and provided with an injection hole for electrolyte to be injected and a sealing plug for sealing the injection hole. The cover plate <NUM> is further provided with a through terminal hole, and the electrode terminal <NUM> is arranged on one side of the cover plate <NUM> and covers the terminal hole. The electrode terminal <NUM> is formed in a cylindrical shape, and is fixed to the cover plate <NUM> by means of a connecting member surrounding an outer periphery thereof.

Optionally, the cover assembly <NUM> further includes a rupture disc <NUM> configured to rupture when the internal pressure of the casing <NUM> reaches a set value.

Optionally, the cover plate <NUM> is provided with a through discharge hole, and the rupture disc <NUM> is fixed to the cover plate <NUM> and covers the discharge hole. The rupture disc <NUM> is provided with a weak area, when the electrode assembly <NUM> generates a large amount of gas due to overcharging, short circuits, etc., gas pressure in the battery cell <NUM> is increased and breaks through the rupture disc <NUM> in the weak area, and the gas is discharged to the outside of the battery cell <NUM> by means the discharge hole, thereby reducing the risk of explosion of the battery cell <NUM>.

With reference to <FIG>, optionally, the cover plate <NUM> of the cover assembly <NUM> provided in the embodiments described above in the application is provided with a first through hole <NUM> that is in communication with spaces on both sides of the cover plate <NUM>. In one embodiment, the first through hole <NUM> penetrates the cover plate <NUM> in a thickness direction of the cover plate <NUM>, that is, an axis of the first through hole <NUM> is parallel to the thickness direction of the cover plate <NUM>.

In some embodiments, the fixing member <NUM> is connected to the cover plate <NUM>. Optionally, the fixing member <NUM> is fixedly connected to the cover plate <NUM> by welding.

Optionally, the second through hole <NUM> of the fixing member <NUM> penetrates the fixing member <NUM> in the thickness direction of the cover plate <NUM>, that is, an axis of the second through hole <NUM> may also be parallel to the thickness direction of the cover plate <NUM>. The gas in the first through hole <NUM> may freely flow into the second through hole <NUM>, and certainly, the gas in the second through hole <NUM> may also freely flow into the first through hole <NUM>.

In some optional embodiments, the fixing member <NUM> is a metal ring with a second through hole <NUM>, which is simple in structure and conducive to connection to the cover plate <NUM> and mounting of the breathable film <NUM>.

In some optional embodiments, the breathable film <NUM> is made of a polymeric material (for example, one or a combination of two or more of polypropylene (PP), polyethylene (PE) and polyurethane (PU)) with breathable properties, and may block liquids. The breathable film <NUM> and the fixing member <NUM> are integrally connected to block the first through hole <NUM>, so the breathable film <NUM> and the fixing member <NUM> may block the electrolyte solution and prevent the electrolyte solution from leaking.

Optionally, the breathable film <NUM> and the fixing member <NUM> are connected by means of a chemical bond (ionic bond or covalent bond). Specifically, the breathable film <NUM> and the fixing member <NUM> are subjected to surface treatment, so as to form functional groups on a surface of the breathable film <NUM> and a surface of the fixing member <NUM>, then the breathable film <NUM> and the fixing member <NUM> are connected by thermal compounding, and the functional group of the breathable film <NUM> and the functional group of the fixing member <NUM> are connected by means of a chemical bond at a bonding surface of the breathable film <NUM> and the fixing member <NUM>.

The breathable film <NUM> is connected to the fixing member <NUM> by means of the chemical bond directly, so a connection strength of the breathable film <NUM> and the fixing member <NUM> may be effectively improved, the risk that the breathable film <NUM> is separated from the fixing member <NUM> under gas impact may be reduced, and the sealing performance of the battery cell <NUM> may be improved.

At least part of the breathable film <NUM> is sandwiched between the fixing member <NUM> and the cover plate <NUM>. The fixing member <NUM> and the cover plate <NUM> grip the breathable film <NUM>, thereby further reducing the risk of falling of the breathable film <NUM>.

With reference to <FIG>, the first through hole <NUM> includes an accommodation section 337a and an extension section 337b extending from the accommodation section 337a, a hole diameter of the accommodation section 337a being greater than that of the extension section 337b. The accommodation section 337a and the extension section 337b are coaxial holes. The extension section 337b is positioned on one side, close to the electrode assembly <NUM>, of the accommodation section 337a. The fixing member <NUM> is at least partially accommodated in the accommodation section 337a so as to reduce the space occupied by the fixing member <NUM> and reduce the overall height of the battery cell <NUM>.

The accommodation section 337a is provided with a bottom wall 337c surrounding the extension section 337b, and the fixing member <NUM> is positioned on one side of the bottom wall 337c. The accommodation section 337a and the extension section 337b with different hole diameters form a step surface (that is, the bottom wall 337c), and the step surface may support the fixing member <NUM>, so the fixing member <NUM> may be conveniently positioned when the fixing member <NUM> and the cover plate <NUM> are welded. The accommodation section 337a is further provided with a side wall surrounding the fixing member <NUM>, and the bottom wall 337c and the side wall define the accommodation section 337a.

The breathable film <NUM> is at least partially sandwiched between the fixing member <NUM> and the bottom wall 337c to separate the second through hole <NUM> from the extension section 337b, and the support <NUM> is arranged on one side, away from the extension section 337b, of the breathable film <NUM>. The breathable film <NUM> is entirely positioned outside the extension section 337b, and an annular edge portion of its periphery is sandwiched between the fixing member <NUM> and the bottom wall 337c, so as to improve the sealing performance and prevent the electrolyte solution from flowing out between the bottom wall 337c and the breathable film <NUM>, and the edge portion is compressed.

Optionally, the fixing member <NUM> is provided with a groove <NUM> arranged around the second through hole <NUM>, and the breathable film <NUM> is at least partially accommodated in the groove <NUM>. By arranging the groove <NUM>, the space occupied by the breathable film <NUM> may be reduced, and the overall thickness of the fixing member <NUM> and the breathable film <NUM> may be reduced. A thickness of the breathable film <NUM> may be slightly greater than a depth of the groove <NUM>. When the fixing member <NUM> and the cover plate <NUM> are assembled, the fixing member <NUM> is attached to the bottom wall 337c, and the breathable film <NUM> is compressed, thereby improving the sealing performance.

Optionally, the fixing member <NUM> is welded to the cover plate <NUM>. Specifically, an interface of the side wall and an outer edge of the fixing member <NUM> is welded.

As an optional embodiment, according to the cover assembly <NUM> provided in the embodiment of the application, the support <NUM> includes a hydrophobic breathable material, the support <NUM> is made of the hydrophobic breathable material, on the basis of meeting a support requirement for the breathable film <NUM>, it may be guaranteed that gas passing through the breathable film <NUM> may smoothly pass through the support <NUM>, so as to guarantee the breathable effect of the breathable film <NUM>, water vapor, etc. may be blocked, so as to avoided the situation that the water vapor enters the battery cell <NUM> to affect the battery cell <NUM>, and in addition, the electrolyte in the battery cell <NUM> may be prevented from being exposed.

Optionally, the second through hole <NUM> is filled with the support <NUM>, the support <NUM> and the fixing member <NUM> are connected by means of a chemical bond (ionic bond or covalent bond). Illustratively, the support <NUM> and the fixing member <NUM> are subjected to surface treatment so as to form functional groups on a surface of the support <NUM> and a surface of the fixing member <NUM>, then the support <NUM> and the fixing member <NUM> are connected by thermal compounding, and the functional group of the support <NUM> and the functional group of the fixing member <NUM> are connected by means of a chemical bond at a bonding surface of the support <NUM> and the fixing member <NUM>. Of course, in some embodiments, the support <NUM> and the fixing member <NUM> may be connected by means of a metal bond, a mechanical interference fit, an adhesive fit, etc., as long as the connection strength of the support <NUM> and the fixing member <NUM> is met.

As shown in <FIG>, as an optional embodiment, the hole diameter of the second through hole <NUM> may remain unchanged in a direction away from the breathable film <NUM>, facilitating formation of the second through hole <NUM> and arrangement of the support <NUM> so as to guarantee the support requirements for the breathable film <NUM>.

With reference to <FIG>, in some embodiments, a hole diameter of at least part, in a length direction, of the second through hole <NUM> is gradually reduced in a direction away from the breathable film <NUM>. When the cover assembly <NUM> is used for the battery cell <NUM>, one side of the breathable film <NUM> faces a battery assembly and makes direct contact with the gas inside the battery cell <NUM>. The hole diameter of at least part, in the length direction, of the second through hole <NUM> is gradually reduced in the direction away from the breathable film <NUM>, so when the breathable film <NUM> deforms outwards in advance under the action of the internal gas pressure of the battery cell <NUM>, a hole wall of the second through hole <NUM> formed in an enclosing mode may provide certain support for the breathable film <NUM> at a hole diameter reducing position, so as to reduce or avoid deformation of the breathable film <NUM>, thereby guaranteeing the breathable effect and the safety performance of the breathable film <NUM>.

Illustratively, with reference to <FIG>, the hole diameter of the second through hole <NUM> may be gradually reduced in a direction away from the breathable film <NUM>, the second through hole <NUM> may be a tapered hole, the second through hole <NUM> is filled with the support <NUM>, and the support <NUM> is connected to the fixing member <NUM>.

In some examples, with reference to <FIG>, the hole diameter of the second through hole <NUM> may be reduced section by section in a direction away from the breathable film <NUM>, the second through hole <NUM> may be a stepped hole, the second through hole <NUM> is filled with the support <NUM>, and the support <NUM> is connected to the fixing member <NUM>.

Certainly, in some other examples, as shown in <FIG>, the hole diameter of the second through holes <NUM> may also be firstly reduced and then increased in a direction away from the breathable film <NUM>, which likewise meets the breathable effect and safety performance requirements of the breathable film <NUM>.

In some optional embodiments, a melting point of the support <NUM> is greater than that of the breathable film <NUM>. When a temperature of the battery cell <NUM> reaches the melting point of the breathable film <NUM>, the breathable film <NUM> deforms and flows, since the melting point of the support <NUM> is greater than that of the breathable film <NUM>, a material of the support <NUM> does not reach the melting point thereof, a support framework effect may be achieved on the breathable film <NUM>, and flowing and deformation of the breathable film <NUM> may be reduced.

As an optional embodiment, according to the cover assembly <NUM> provided in the embodiment of the application, a difference between the melting point of the support <NUM> and the melting point of the breathable film <NUM> is greater than or equal to <NUM>. By means of the above arrangement, the support <NUM> may be effectively prevented from deforming when the breathable film <NUM> deforms and flows, thereby guaranteeing a support effect on the breathable film <NUM>.

In some optional embodiments, a shear strength at a joint between the support <NUM> and the fixing member <NUM> is greater than or equal to <NUM> MPa. By means of the above arrangement, when internal pressure of the battery cell <NUM> is increased, shape stability of the support <NUM> and stability of connection strength between the support <NUM> and the fixing member <NUM> may be guaranteed, thereby guaranteeing the support effect on the breathable film <NUM>, preventing the breathable film <NUM> from deforming or even breaking, and guaranteeing the breathable effect of the breathable film <NUM>.

As one optional embodiment, according to the cover assembly <NUM> provided in the embodiment of the application, the breathability of the support <NUM> is greater than that of the breathable film <NUM>. Since the breathable film <NUM> is made of a material for controlling the entire breathable effect of the battery, gas passing through the breathable film <NUM> needs to be smoothly discharged from the support <NUM> to the outside of the battery cell <NUM>. The breathability of the support <NUM> is greater than that of the breathable film <NUM>, so the gas, passing through the breathable film <NUM>, in the battery cell <NUM> may be smoothly discharged from the support <NUM>, so as to guarantee the safety performance of the battery cell <NUM>.

In some optional embodiments, a difference between a maximum size of the breathable film <NUM> and a maximum size of the support <NUM> is greater than or equal to <NUM> in a radial direction of the first through hole <NUM>, and an orthographic projection of a geometric center of the breathable film <NUM> coincides with an orthographic projection of a geometric center of the support <NUM> in an axial direction of the first through hole <NUM>. By means of the above arrangement, a combination area between a periphery of the breathable film <NUM> and the support <NUM> may be guaranteed, and composite strength and sealing performance between the breathable film <NUM> and the support <NUM> may be guaranteed.

As shown in <FIG>, in another aspect, the embodiment of the application further provides a method for manufacturing a battery cell <NUM>. The method may be used to prepare the battery cell of the embodiment shown in <FIG>, and includes:.

According to the battery cell <NUM> prepared by means of the method for manufacturing the battery cell <NUM> provided in the embodiment of the application, gas generated in the battery cell may be discharged to the outside of the battery cell <NUM> by means of the breathable film <NUM>, and the gas is prevented from being accumulated in the casing <NUM>, thereby improving performance of the electrode assembly <NUM> and prolonging the service life of the battery cell <NUM>. By arranging the support <NUM>, the breathable film <NUM> may be supported, it may be guaranteed that the breathable film <NUM> is still kept intact under the condition of large internal pressure of the battery cell <NUM>, damage to the breathable film <NUM> may be avoided, breathable performance of the breathable film <NUM> in the entire service life of the battery cell <NUM> may be guaranteed, and further the safety performance of the battery cell <NUM> may be guaranteed.

As shown in <FIG>, in yet another aspect, the embodiment of the application further provides an apparatus <NUM> for manufacturing a battery cell <NUM>. The apparatus <NUM> may be used for manufacturing the battery cell of the embodiment shown in <FIG> and includes a first assembling device <NUM>, a second assembling device <NUM> and a third assembling device <NUM>. The first assembling device <NUM> is configured to provide a casing <NUM> provided with an opening. The second assembling device <NUM> is configured to provide an electrode assembly <NUM>, where the electrode assembly <NUM> is arranged in the casing <NUM>. The third assembling device <NUM> is configured to provide a cover assembly <NUM>, where the cover assembly <NUM> includes a cover plate <NUM>, a fixing member <NUM>, a breathable film <NUM> and a support <NUM>, the cover plate <NUM> being provided with a first through hole <NUM>, the fixing member <NUM> being used for being connected to the cover plate <NUM> and provided with a second through hole <NUM>, where the second through hole <NUM> is configured to be in gas communication with the first through hole <NUM>, the breathable film <NUM> being connected to the fixing member <NUM> and used for covering the second through hole <NUM>, the second through hole <NUM> being filled with the support <NUM>, and the support <NUM> being connected to the fixing member <NUM> and used for supporting the breathable film <NUM>, and the cover assembly <NUM> is arranged at the opening to be connected to the casing <NUM> by means of the cover plate <NUM>, and gas in the casing <NUM> passes through the breathable film <NUM> and the fixing member <NUM>.

The apparatus for manufacturing the battery cell <NUM> provided in the embodiment of the application may be used for manufacturing the battery cell <NUM> provided in the above embodiments, gas generated in the battery cell <NUM> manufactured by means of the apparatus may be discharged to the outside of the battery cell <NUM> by means of the breathable film <NUM>, and the gas is prevented from being accumulated in the casing <NUM>, thereby improving performance of the electrode assembly <NUM> and prolonging the service life of the battery cell <NUM>. By arranging the support <NUM>, the breathable film <NUM> may be supported, it may be guaranteed that the breathable film <NUM> is still kept intact under the condition of large internal pressure of the battery cell <NUM>, damage to the breathable film <NUM> may be avoided, breathable performance of the breathable film <NUM> in the entire service life of the battery cell <NUM> may be guaranteed, and further the safety performance of the battery cell <NUM> may be guaranteed.

Claim 1:
A cover assembly (<NUM>) of a battery cell (<NUM>), comprising:
a cover plate (<NUM>) provided with a first through hole (<NUM>) comprising an accommodation section (337a) and an extension section (337b) extending from the accommodation section (337a), a hole diameter of the accommodation section (337a) being greater than a hole diameter of the extension section (337b);
a fixing member (<NUM>) used for being connected to the cover plate (<NUM>) and provided with a second through hole (<NUM>), wherein the second through hole (<NUM>) is configured to be in gas communication with the first through hole (<NUM>);
a breathable film (<NUM>) connected to the fixing member (<NUM>) and used for covering the second through hole (<NUM>); and
a support (<NUM>) filled in the second through hole (<NUM>), connected to the fixing member (<NUM>) and used for supporting the breathable film (<NUM>) and allowing gas passing through the breathable film (<NUM>) to pass through, wherein the fixing member (<NUM>) and the support (<NUM>) are at least partially accommodated in the accommodation section (337a), and
wherein the accommodation section (337a) is provided with a bottom wall (337c) surrounding the extension section (337b), the breathable film (<NUM>) is at least partially sandwiched between the fixing member (<NUM>) and the bottom wall (337c) to separate the second through hole (<NUM>) from the extension section (337b), and the support (<NUM>) is arranged on one side, away from the extension section (337b), of the breathable film (<NUM>).