Cover plate assembly and battery monomer
By introducing a high-temperature resistant sealing ring and top plastic in the cover assembly of the battery cell, the problem of sealing and insulation failure under extreme high temperatures is solved, improving the sealing reliability and safety of the battery cell.
Patent Information
- Application Number
- CN202411607335.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-12
AI Technical Summary
Existing battery cells may fail to seal and insulate under extreme high temperatures, leading to safety risks.
A high-temperature resistant layer is introduced into the sealing ring and the upper plastic of the cover plate assembly, and the high-temperature resistant layer is covered by an overlay layer to ensure that the sealing performance is maintained at extreme temperatures.
It improves the sealing reliability of individual battery cells under extreme temperatures, prevents sealing and insulation failure, and reduces safety risks.
Smart Images
Figure CN122025943A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery technology, and in particular to a cover plate assembly and a battery cell. Background Technology
[0002] A single battery cell includes a casing, a cover assembly, and an electrode assembly. The electrode assembly is housed within the casing, and the cover assembly is mounted on the casing and seals its opening. The cover assembly includes a cover plate, terminals, upper plastic, lower plastic, and a sealing ring. The terminals are positioned within through holes in the cover plate. Plastic is applied above the cover plate at a location corresponding to the terminals, and lower plastic is applied below the cover plate at a location corresponding to the terminals. Because the upper plastic and sealing ring are typically made of materials with narrow temperature ranges, such as polyolefins and fluororubber, the upper plastic or sealing ring is prone to softening, deformation, or even melting under extreme high temperatures or other abnormal operating conditions. This can cause sealing and insulation failure in the battery cell, posing a serious safety risk. Summary of the Invention
[0003] The purpose of this invention is to provide a cover plate assembly and a battery cell to solve the technical problems of sealing and insulation failure of battery cells.
[0004] In a first aspect, this application provides a cover plate assembly for a battery cell, comprising: a cover plate having mounting holes having intersecting axial and radial directions, the mounting holes penetrating the cover plate axially; a terminal post disposed within the mounting holes; and a sealing ring axially sleeved between the terminal post and the cover plate, the sealing ring comprising a first covering layer and a first high-temperature resistant layer, the first covering layer covering the surface of the first high-temperature resistant layer, the melting point of the first high-temperature resistant layer being greater than the melting point of the first covering layer.
[0005] In some embodiments, the cover plate has a raised ring that extends radially into a mounting hole; the pole includes a column portion and a connecting portion, the column portion passing through the mounting hole, and the connecting portion being axially connected to one end of the column portion; wherein, a sealing ring is axially disposed between the raised ring and the connecting portion, and the connecting portion extends radially and partially overlaps the cover plate in the axial direction.
[0006] In some embodiments, the first high-temperature resistant layer is an annular structure, and the maximum dimension between the inner wall and the outer wall of the first high-temperature resistant layer in the radial direction is R1; the axial distance between the convex ring and the connecting part is D1; wherein, R1 and D1 satisfy: R1≥D1.
[0007] In some embodiments, the material used for the first coating layer includes at least one of fluororubber, silicone rubber, and polyolefin; the material used for the first high-temperature resistant layer includes at least one of high-temperature resistant polymer, inorganic material, and organic-inorganic mixture.
[0008] In some embodiments, the high-temperature resistant polymer includes at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic material includes at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; the organic-inorganic mixture includes at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
[0009] In some embodiments, the flexural modulus of the first coating layer is K1, and the flexural modulus of the first high-temperature resistant layer is K2, wherein K1 and K2 satisfy: K1 > K2.
[0010] Secondly, this application provides a cover plate assembly for a battery cell, comprising: a cover plate having mounting holes having intersecting axial and radial directions, the mounting holes penetrating the cover plate axially; an electrode post disposed within the mounting holes; and an upper plastic layer disposed on the cover plate, a portion of the upper plastic layer extending into the mounting holes and disposed radially between the electrode post and the cover plate; the upper plastic layer includes a second coating layer and a second high-temperature resistant layer, the second coating layer covering the surface of the second high-temperature resistant layer, the melting point of the second high-temperature resistant layer being greater than the melting point of the second coating layer.
[0011] In some embodiments, the cover plate has a raised ring that extends radially into a mounting hole; the upper plastic includes a first part and a second part connected together, the second part being axially connected to the first part, wherein the first part is radially disposed between the raised ring and the pole post, and the second part is located on the raised ring; wherein the first part includes a second covering layer and a second high-temperature resistant layer.
[0012] In some embodiments, the second high-temperature resistant layer is an annular structure, and the maximum dimension between the inner wall and the outer wall of the second high-temperature resistant layer in the radial direction is R2; the distance between the outer wall of the pole post and the convex ring in the radial direction is D2; wherein, R2 and D2 satisfy the following condition: R2≥D2.
[0013] In some embodiments, the material used for the second coating layer includes at least one of polypropylene, polyethylene, polyimide, and conductive polypropylene; the material used for the second high-temperature resistant layer includes at least one of high-temperature resistant polymer, inorganic material, and organic-inorganic mixture.
[0014] In some embodiments, the high-temperature resistant polymer includes at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic material includes at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; the organic-inorganic mixture includes at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
[0015] In some embodiments, the flexural modulus of the second high-temperature resistant layer is K3, and the flexural modulus of the second covering layer is K4; wherein K3 and K4 satisfy: K3 > K4.
[0016] Thirdly, this application provides a cover plate assembly for a battery cell, comprising: a cover plate having a mounting hole having intersecting axial and radial directions, the mounting hole penetrating the cover plate axially; a terminal post disposed within the mounting hole; a sealing ring axially sleeved between the terminal post and the cover plate, the sealing ring including a first covering layer and a first high-temperature resistant layer, the first covering layer covering the surface of the first high-temperature resistant layer, the melting point of the first high-temperature resistant layer being greater than the melting point of the first covering layer; an upper plastic layer disposed on the side of the cover plate away from the sealing ring, a portion of the upper plastic layer extending into the mounting hole and disposed radially between the upper plastic layer and the cover plate; and the upper plastic layer including a second covering layer and a second high-temperature resistant layer, the second covering layer covering the surface of the second high-temperature resistant layer, the melting point of the second high-temperature resistant layer being greater than the melting point of the second covering layer.
[0017] In some embodiments, the cover plate has a raised ring that extends radially into a mounting hole; the pole includes a column portion and a connecting portion, the column portion passing through the mounting hole, and the connecting portion being axially connected to one end of the column portion; wherein, a sealing ring is axially disposed between the raised ring and the connecting portion, and the connecting portion extends radially and partially overlaps the cover plate in the axial direction.
[0018] In some embodiments, the upper plastic includes a first part and a second part connected together, the second part being axially connected to the first part, wherein the first part is radially disposed between the convex ring and the pole post, and the second part is located on the convex ring; wherein the first part includes a second covering layer and a second high-temperature resistant layer.
[0019] In some embodiments, the first high-temperature resistant layer is an annular structure, and the maximum radial dimension between the inner and outer walls of the first high-temperature resistant layer is R1; the axial distance between the convex ring and the connecting portion is D1; wherein R1 and D1 satisfy R1≥D1; the second high-temperature resistant layer is an annular structure, and the radial dimension of the second high-temperature resistant layer is R2; the radial distance between the outer wall of the pole post and the convex ring is D2; wherein R2 and D2 satisfy R2≥D2.
[0020] In some embodiments, the material used for the first coating layer includes at least one of fluororubber, silicone rubber, and polyolefin; the material used for the second coating layer includes at least one of polypropylene, polyethylene, polyimide, and conductive polypropylene; and the materials used for both the first high-temperature resistant layer and the second high-temperature resistant layer include at least one of high-temperature resistant polymer, inorganic material, and organic-inorganic mixture.
[0021] In some embodiments, the high-temperature resistant polymer includes at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic material includes at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; the organic-inorganic mixture includes at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
[0022] In some embodiments, the flexural modulus of the first coating layer is K1, the flexural modulus of the first high-temperature resistant layer is K2, the flexural modulus of the second high-temperature resistant layer is K3, and the flexural modulus of the second coating layer is K4; wherein, K1, K2, K3, and K4 satisfy: K1 > K2 ≥ K3 > K4.
[0023] In some embodiments, the melting point of the first coating layer is P1, the melting point of the first high-temperature resistant layer is P2, the melting point of the second high-temperature resistant layer is P3, and the melting point of the second coating layer is P4; wherein, P1, P2, P3, and P4 satisfy: P2 > P3 ≥ P1 > P4.
[0024] Fourthly, this application provides a battery cell, including: a housing having an opening; and a cover assembly as described in any of the above embodiments, the cover assembly being disposed on the housing for closing the opening.
[0025] The technical advantage of this invention lies in providing a cover plate assembly and a battery cell. By sealing the mounting holes of the cover plate with a sealing ring and / or an outer plastic layer, the terminal post is fixed within the mounting holes. A high-temperature resistant layer is provided inside the sealing ring and / or the outer plastic layer, and this high-temperature resistant layer is embedded by a covering layer. This allows the cover plate assembly to seal the mounting holes where the terminal post is located under any temperature conditions, and improves the sealing reliability of the battery cell under extreme temperatures. Attached Figure Description
[0026] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.
[0027] Figure 1 A schematic diagram of the structure of the cover plate assembly provided in the embodiments of this application. Figure 1 .
[0028] Figure 2 for Figure 1 A schematic diagram of the provided sealing ring.
[0029] Figure 3 for Figure 2 Cross-sectional view along the AA direction.
[0030] Figure 4 A schematic diagram of the structure of the cover plate assembly provided in the embodiments of this application. Figure 2 .
[0031] Figure 5 for Figure 4 The provided structural diagram of the upper plastic layer.
[0032] Figure 6 This is a schematic diagram of the cover plate assembly provided in an embodiment of this application.
[0033] Figure 7 A schematic diagram of the structure of the cover plate assembly provided in the embodiments of this application. Figure 3 .
[0034] Figure 8 for Figure 7 A schematic diagram of another form of the provided cover plate assembly.
[0035] Figure 9 This is a schematic diagram of the structure of a battery cell provided in an embodiment of this application.
[0036] Figure 10 This is a structural diagram of a conventional cover plate assembly.
[0037] Figure 11 for Figure 10 A schematic diagram of another form of the provided cover plate assembly.
[0038] Component labels in the attached diagram:
[0039] 1. Cover plate; 11. Raised ring; 101. Mounting hole; 102. Explosion-proof hole; 103. Liquid injection hole;
[0040] 2. Pole post; 21. Post body; 22. Connecting part;
[0041] 3. Sealing ring; 31. First covering layer; 32. First high-temperature resistant layer;
[0042] 4. Upper plastic layer; 41. Second coating layer; 42. Second high-temperature resistant layer; 401. First part; 402. Second part; 4021. Main body; 4022. First protrusion; 4023. Second protrusion; 4024. Slot;
[0043] 5. Explosion-proof valve; 51. First explosion-proof patch; 52. Second explosion-proof patch;
[0044] 6. Plastic;
[0045] 100 Cover assembly; 200 Housing; 20 Opening. Detailed Implementation
[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0047] In the description of this application, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.
[0048] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0049] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.
[0050] To address the technical problems of sealing and insulation failure in battery cells, this application provides a cover plate assembly and a battery cell including the cover plate assembly. The mounting holes of the cover plate are sealed by a sealing ring and / or an outer plastic layer, thereby fixing the terminal post within the mounting holes. A high-temperature resistant layer is provided inside the sealing ring and / or the outer plastic layer, and this high-temperature resistant layer is further embedded by a covering layer. This allows the cover plate assembly to seal the mounting holes containing the terminal post under any temperature conditions and improves the sealing reliability of the battery cell under extreme temperatures. A detailed description follows.
[0051] like Figure 1 As shown in the figure, this application provides a cover plate assembly 100, including a cover plate 1, a pole post 2, and a sealing ring 3.
[0052] The cover plate 1 is generally rectangular in shape and has a mounting hole 101. The mounting hole 101 has intersecting axial direction Y and radial direction X, and the mounting hole 101 penetrates the cover plate 1 along the axial direction Y. The cover plate 1 has a protruding ring 11, which extends into the mounting hole 101 along the radial direction X.
[0053] The electrode post 2 is disposed within the mounting hole 101. It can be understood that the electrode post 2 is installed within the mounting hole 101. The electrode post 2 includes a post body 21 and a connecting part 22. The post body 21 passes through the mounting hole 101, and the connecting part 22 is connected to one end (bottom end) of the post body 21 along the axial direction Y. Optionally, the post body 21 and the connecting part 22 are integrally formed, which can improve assembly efficiency.
[0054] The sealing ring 3 is fitted onto the outer wall of the pole post 2 in the axial direction Y. Specifically, the sealing ring 3 is fitted onto the outer wall of the pole body 21 and is positioned between the convex ring 11 and the connecting part 22 in the axial direction Y. The connecting part 22 extends radially X and partially overlaps with the cover plate 1 in the axial direction Y to seal the mounting hole 101.
[0055] like Figure 2 and Figure 3 As shown, the sealing ring 3 includes a first covering layer 31 and a first high-temperature resistant layer 32. The first covering layer 31 covers the surface of the first high-temperature resistant layer 32. The melting point of the first high-temperature resistant layer 32 is greater than that of the first covering layer 31. In this way, under abnormal conditions (such as thermal runaway), the sealing ring 3 can still fit tightly with the cover plate 1 and the electrode post 2, and can seal the residual gas or excess electrolyte inside the housing 200.
[0056] like Figures 1 to 3 As shown, the first high-temperature resistant layer 32 has an annular structure. In the radial direction X, the maximum dimension between the inner and outer walls of the first high-temperature resistant layer 32 is R1. For example, the first high-temperature resistant layer 32 is a ring, and its ring width is the outer radius of the first high-temperature resistant layer 32 minus the inner radius of the first high-temperature resistant layer 32. The distance between the convex ring 11 and the connecting portion 22 in the axial direction Y is D1. It can be understood that the "distance between the convex ring 11 and the connecting portion 22" is the vertical distance between the lower surface of the convex ring 11 and the upper surface of the connecting portion 22.
[0057] R1 and D1 satisfy the condition that R1≥D1. In this way, under any state (such as elastic deformation), the sealing ring 3 can always fill the gap between the outer wall of the pole post 2 and the inner wall of the mounting hole 101, as well as the gap between the convex ring 11 and the connecting part 22, thereby sealing the mounting hole 101 and further improving the sealing performance of the cover plate assembly 100.
[0058] The first covering layer 31 has a dimension of R in the radial direction X. 11Where R1 < R 11 And R1 = (1 / 4 ~ 1 / 2)R 11 In this way, the sealing ring 3 not only has good sealing performance but also can withstand high temperatures. Therefore, even if the cover plate assembly 100 is in a high-temperature environment, the sealing ring 3 is not likely to melt due to heat, thus preventing sealing failure.
[0059] The flexural modulus of the first coating layer 31 is K1, and the flexural modulus of the first high-temperature resistant layer 32 is K2, wherein K1 and K2 satisfy: K1 > K2.
[0060] The sealing ring 3 is an integrally formed circular structure. Specifically, both the first covering layer 31 and the first high-temperature resistant layer 32 are circular structures, with the first covering layer 31 covering the outer surface of the first high-temperature resistant layer 32 to form a wrapping structure.
[0061] The material used for the first coating layer 31 includes at least one of fluororubber, silicone rubber, and polyolefin.
[0062] The material used in the first high-temperature resistant layer 32 includes at least one of high-temperature resistant polymers, inorganic materials, and organic-inorganic mixtures. Specifically, the high-temperature resistant polymer includes at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic material includes at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; and the organic-inorganic mixture includes at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
[0063] In preparing the sealing ring 3, the high-temperature resistant material raw material is first shaped into a first high-temperature resistant layer 32 of a specific size through sintering, casting, UV curing and other means; then, the outer surface of the first high-temperature resistant layer 32 is shaped into a first covering layer 31 of a specific size through sintering, casting, UV curing and other means, thereby obtaining the structure in which the first covering layer 31 wraps the first high-temperature resistant layer 32, i.e., the sealing ring 3.
[0064] During the installation of the cover plate 1, pole post 2 and sealing ring 3, the sealing ring 3 is first fitted onto the outer wall of the pole body 21, and then the pole body 21 is installed in the mounting hole 101. At this time, with the cooperation of the cover plate 1 and the connecting part 22, the sealing ring 3 is restricted to the position of the mounting hole 101, so that the sealing ring 3 is tightly fitted with the cover plate 1 and pole post 2, and the mounting hole 101 is sealed.
[0065] like Figure 4 As shown, another embodiment of this application provides a cover plate assembly 100, including a cover plate 1, an electrode post 2, and an upper plastic 4.
[0066] The cover plate 1 is generally rectangular in shape and has a mounting hole 101. The mounting hole 101 has intersecting axial direction Y and radial direction X, and the mounting hole 101 penetrates the cover plate 1 along the axial direction Y. The cover plate 1 has a protruding ring 11, which extends into the mounting hole 101 along the radial direction X.
[0067] The electrode post 2 is disposed within the mounting hole 101. It can be understood that the electrode post 2 is installed within the mounting hole 101. The electrode post 2 includes a post body 21 and a connecting part 22. The post body 21 passes through the mounting hole 101, and the connecting part 22 is connected to one end (bottom end) of the post body 21 along the axial direction Y. Optionally, the post body 21 and the connecting part 22 are integrally formed, which can improve assembly efficiency.
[0068] The upper plastic 4 is disposed on the cover plate 1, and a portion of the upper plastic 4 extends into the mounting hole 101. The upper plastic 4 abuts against the outer wall of the electrode post 2 and is located between the electrode post 2 and the cover plate 1 in the radial direction X. The upper plastic 4 includes a second coating layer 41 and a second high-temperature resistant layer 42. The second coating layer 41 covers the surface of the second high-temperature resistant layer 42. The melting point of the second high-temperature resistant layer 42 is greater than that of the second coating layer 41. In this way, under abnormal conditions (such as thermal runaway), the upper plastic 4 can still fit tightly with the cover plate 1 and the electrode post 2 and can seal the residual gas or excess electrolyte inside the housing 200.
[0069] like Figure 4 and Figure 5 As shown, the upper plastic 4 includes a first part 401 and a second part 402 connected together, with the dotted line as the boundary. The second part 402 is connected to the first part 401 along the axial direction Y. The first part 401 is disposed between the convex ring 11 and the pole post 2 along the radial direction X, and the second part 402 is disposed on the convex ring 11. It can be understood that the first part 401 is disposed at the mounting hole 101, and the first part 401 cooperates with the cover plate 1 and the pole post 2 to seal the mounting hole 101 where the pole post 2 is located.
[0070] The first part 401 includes a second covering layer 41 and a second high-temperature resistant layer 42, which allows the second high-temperature resistant layer 42 to be disposed at the mounting hole 101 to improve the sealing performance of the cover assembly. Optionally, the first part 401 and the second part 402 both include a second covering layer 41 and a second high-temperature resistant layer 42, such that the second high-temperature resistant layer 42 extends from the mounting hole 101 to the surface of the cover 1, so that the entire pole post 2 is covered by the second high-temperature resistant layer 42, which can further improve the sealing performance of the cover assembly.
[0071] like Figures 4 to 5As shown, the second high-temperature resistant layer 42 has a ring-shaped structure. In the radial direction X, the maximum distance between the inner and outer walls of the second high-temperature resistant layer 42 is R2. For example, if the second high-temperature resistant layer 42 is a ring, the ring width of the second high-temperature resistant layer 42 is the outer radius of the second high-temperature resistant layer 42 minus the inner radius of the second high-temperature resistant layer 42. In the radial direction X, the distance between the outer wall of the pole post 2 and the convex ring 11 is D2; where R2 and D2 satisfy: R2 ≥ D2. It can be understood that the "distance between the outer wall of the pole post 2 and the convex ring 11" is the vertical distance between the outer wall of the pole post 2 and the convex ring 11.
[0072] R2 and D2 satisfy the condition that R2≥D2. In this way, under any state (such as elastic deformation), the upper plastic 4 can always fill the gap between the outer wall of the pole post 2 and the inner wall of the mounting hole 101, thereby sealing the mounting hole 101 and further improving the sealing performance of the cover plate assembly 100.
[0073] The second covering layer 41 has a dimension R in the radial direction X. 22 Where R2 < R 22 And R2 = (1 / 4 ~ 1 / 2)R 22 This allows the plastic 4 to not only have good sealing performance but also withstand high temperatures. Therefore, even if the cover assembly 100 is exposed to certain environments, the sealing ring 3 is less likely to melt due to heat, thus preventing sealing failure.
[0074] The flexural modulus of the second high-temperature resistant layer 42 is K3, and the flexural modulus of the second covering layer 41 is K4; wherein, K3 and K4 satisfy: K3 > K4.
[0075] like Figure 5 As shown, the second part 402 includes a body part 4021, a first protrusion 4022, and a second protrusion 4023. The body part 4021 has a ring structure, and a groove 4024 matching the cover plate 11 is formed on the surface of the body part 4021 facing the cover plate 11. The first protrusion 4022 protrudes from the inner wall of the body part 4021 and extends in the radial X direction to abut against the outer wall of the pole post 2. The second protrusion 4023 protrudes from the outer wall of the body part 4021 and extends in both the radial X and axial Y directions, wherein the second protrusion 4023 abuts against the top surface of the cover plate 11 in the axial Y direction. Therefore, the second part 402 can confine the pole post 2 within the mounting hole 101 and achieve the fixation of the cover plate 1, the pole post 2, and the upper plastic 4.
[0076] The upper plastic layer 4 is a one-piece molded ring structure. Specifically, both the second covering layer 41 and the second high-temperature resistant layer 42 are ring structures, with the second covering layer 41 covering the outer surface of the second high-temperature resistant layer 42 to form an encapsulation structure.
[0077] The material used for the second coating layer 41 includes at least one of polypropylene, polyethylene, polyimide, and conductive polypropylene.
[0078] The material used for the second high-temperature resistant layer 42 includes at least one of high-temperature resistant polymers, inorganic materials, and organic-inorganic mixtures. Specifically, the high-temperature resistant polymers include at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic materials include at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; and the organic-inorganic mixtures include at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
[0079] In preparing the upper plastic 4, the high-temperature resistant material raw material is first shaped into a second high-temperature resistant layer 42 of a specific size through sintering, casting, UV curing and other means; then, the outer surface of the first high-temperature resistant layer 32 is shaped into a second covering layer 41 of a specific size through sintering, casting, UV curing and other means, thereby obtaining the structure in which the second covering layer 41 wraps the second high-temperature resistant layer 42, that is, the upper plastic 4.
[0080] During the installation of the cover plate 1, the pole post 2, and the upper plastic 4, the upper plastic 4 is first placed on the outer wall of the pole post 2, and then the pole post 2 is installed in the mounting hole 101. At this time, with the cooperation of the cover plate 1 and the pole post 2, the upper plastic 4 is restricted to the position of the mounting hole 101, so that the upper plastic 4 fits tightly with the cover plate 1 and the pole post 2, and the mounting hole 101 is sealed.
[0081] like Figures 6 to 8 As shown, the cover plate assembly 100 includes a cover plate 1, a pole post 2, a sealing ring 3, an upper plastic 4, an explosion-proof valve 5, and a lower plastic 6.
[0082] The cover plate 1 is roughly rectangular in shape and has mounting holes 101, explosion-proof holes 102, and liquid injection holes 103. The mounting holes 101 have intersecting axial directions Y and radial directions X, and the mounting holes 101 penetrate the cover plate 1 along the axial direction Y. The cover plate 1 has a protruding ring 11, which extends radially X into the mounting holes 101.
[0083] The pole post 2 is installed in the mounting hole 101, and the explosion-proof valve 5 is installed in the explosion-proof hole 102. It can be understood that the pole post 2 is installed in the mounting hole 101, and the explosion-proof valve 5 is installed in the explosion-proof hole 102.
[0084] The pole post 2 includes a post body 21 and a connecting part 22. The post body 21 passes through the mounting hole 101, and the connecting part 22 is connected to one end (bottom end) of the post body 21 along the axial direction Y. Optionally, the post body 21 and the connecting part 22 are integrally formed, which can improve assembly efficiency.
[0085] The electrode post 2 may include a positive electrode post 2 and a negative electrode post 2. An electrode assembly is provided inside the housing 200, comprising a positive electrode plate and a negative electrode plate stacked together, with a diaphragm disposed between the positive and negative electrode plates. The positive electrode post 2 can be connected to a positive electrode tab connected to the positive electrode plate, and the negative electrode post 2 can be connected to a negative electrode tab connected to the negative electrode plate. The mounting hole 101 corresponding to the positive electrode post 2 is the positive electrode mounting hole 101, and the mounting hole 101 corresponding to the negative electrode post 2 is the negative electrode mounting hole 101. Two sealing rings 3 are respectively disposed at the positive electrode mounting hole 101 and the negative electrode mounting hole 101 to achieve a sealing effect on the positive electrode mounting hole 101 and the negative electrode mounting hole 101.
[0086] The explosion-proof valve 5 includes a first explosion-proof patch 51 and a second explosion-proof patch 52, which are arranged vertically within the explosion-proof hole 102. The explosion-proof valve 5 opens when subjected to pressure and reduces the risk of deflagration of the battery cells.
[0087] The sealing ring 3 is fitted onto the outer wall of the pole post 2 in the axial direction Y. Specifically, the sealing ring 3 is fitted onto the outer wall of the pole body 21 and is positioned between the convex ring 11 and the connecting part 22 in the axial direction Y. The connecting part 22 extends radially X and partially overlaps with the cover plate 1 in the axial direction Y to seal the mounting hole 101.
[0088] The sealing ring 3 includes a first covering layer 31 and a first high-temperature resistant layer 32. The first covering layer 31 covers the surface of the first high-temperature resistant layer 32. The melting point of the first high-temperature resistant layer 32 is greater than that of the first covering layer 31. In this way, under abnormal conditions (such as thermal runaway), the sealing ring 3 can still fit tightly with the cover plate 1 and the electrode post 2, and can seal the residual gas or excess electrolyte inside the housing 200.
[0089] The upper plastic 4 is disposed on the side of the cover plate 1 away from the sealing ring 3. A portion of the upper plastic 4 extends into the mounting hole 101 and abuts against the outer wall of the electrode post 2, and is located between the electrode post 2 and the cover plate 1 in the radial direction X. The upper plastic 4 includes a second covering layer 41 and a second high-temperature resistant layer 42. The second covering layer 41 covers the surface of the second high-temperature resistant layer 42. The melting point of the second high-temperature resistant layer 42 is greater than that of the second covering layer 41. In this way, under abnormal conditions (such as thermal runaway), the upper plastic 4 can still fit tightly with the cover plate 1 and the electrode post 2, and can seal the residual gas or excess electrolyte inside the housing 200.
[0090] The upper plastic part 4 includes a first part 401 and a second part 402 connected together. The first part 401 is disposed on the convex ring 11, and the second part 402 is connected to the first part 401 along the axial direction Y. The first part 401 is disposed between the convex ring 11 and the pole post 2 along the radial direction X, and the second part 402 is disposed on the convex ring 11. It can be understood that the first part 401 is disposed at the mounting hole 101, and the first part 401 cooperates with the cover plate 1 and the pole post 2 to seal the mounting hole 101 where the pole post 2 is located.
[0091] The first part 401 includes a second covering layer 41 and a second high-temperature resistant layer 42, which allows the second high-temperature resistant layer 42 to be disposed at the mounting hole 101 to improve the sealing performance of the cover assembly. Optionally, the first part 401 and the second part 402 both include a second covering layer 41 and a second high-temperature resistant layer 42, such that the second high-temperature resistant layer 42 extends from the mounting hole 101 to the surface of the cover 1, so that the entire pole post 2 is covered by the second high-temperature resistant layer 42, which can further improve the sealing performance of the cover assembly.
[0092] The second part 402 includes a main body 4021, a first protrusion 4022, and a second protrusion 4023. See below. Figure 5 The main body 4021 has a circular structure, and a groove 4024 matching the cover plate 1 is formed on the surface of the main body 4021 facing the cover plate 1. A first protrusion 4022 protrudes from the inner wall of the main body 4021 and extends in the radial X direction to abut against the outer wall of the pole post 2. A second protrusion 4023 protrudes from the outer wall of the main body 4021 and extends in both the radial X and axial Y directions, wherein the second protrusion 4023 abuts against the top surface of the cover plate 1 in the axial Y direction. Therefore, the upper second part 402 can confine the pole post 2 within the mounting hole 101 and achieve the fixation of the cover plate 1, the pole post 2, and the upper plastic 4.
[0093] The first high-temperature resistant layer 32 has an annular structure, and the maximum dimension between the inner and outer walls of the first high-temperature resistant layer 32 in the radial direction X is R1. For example, the first high-temperature resistant layer 32 is a ring, and the ring width of the first high-temperature resistant layer 32 is the outer radius of the first high-temperature resistant layer 32 minus the inner radius of the first high-temperature resistant layer 32. The distance between the convex ring 11 and the connecting part 22 in the axial direction Y is D1. It can be understood that the "distance between the convex ring 11 and the connecting part 22" is the vertical distance between the lower surface of the convex ring 11 and the upper surface of the connecting part 22.
[0094] R1 and D1 satisfy the condition that R1≥D1. In this way, under any state (such as elastic deformation), the sealing ring 3 can always fill the gap between the outer wall of the pole post 2 and the inner wall of the mounting hole 101, as well as the gap between the convex ring 11 and the connecting part 22, thereby sealing the mounting hole 101 and further improving the sealing performance of the cover plate assembly 100.
[0095] The second high-temperature resistant layer 42 has a ring-shaped structure. In the radial direction X, the maximum distance between the inner and outer walls of the second high-temperature resistant layer 42 is R2. For example, if the second high-temperature resistant layer 42 is a ring, the ring width of the second high-temperature resistant layer 42 is the outer radius of the second high-temperature resistant layer 42 minus the inner radius of the second high-temperature resistant layer 42. In the radial direction X, the distance between the outer wall of the pole post 2 and the convex ring 11 is D2; where R2 and D2 satisfy: R2 ≥ D2. It can be understood that the "distance between the outer wall of the pole post 2 and the convex ring 11" is the perpendicular distance between the outer wall of the pole post 2 and the convex ring 11.
[0096] R2 and D2 satisfy the condition that R2≥D2. In this way, under any state (such as elastic deformation), the upper plastic 4 can always fill the gap between the outer wall of the pole post 2 and the inner wall of the mounting hole 101, thereby sealing the mounting hole 101 and further improving the sealing performance of the cover plate assembly 100.
[0097] The material used for the first coating layer 31 includes at least one of fluororubber, silicone rubber, and polyolefin.
[0098] The material used for the second coating layer 41 includes at least one of polypropylene, polyethylene, polyimide, and conductive polypropylene.
[0099] The materials used in the first high-temperature resistant layer 32 and the second high-temperature resistant layer 42 both include at least one of the following: high-temperature resistant polymers, inorganic materials, and organic-inorganic mixtures. Specifically, the high-temperature resistant polymers include at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic materials include at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; and the organic-inorganic mixtures include at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
[0100] In some embodiments, the first high-temperature resistant layer 32 and the second high-temperature resistant layer 42 may be made of the same or different materials. For example, the first high-temperature resistant layer 32 and the second high-temperature resistant layer 42 may be made of polyetheretherketone (PEEK), which will not be described in detail here.
[0101] In some embodiments, the flexural modulus of the first covering layer 31 is K1, the flexural modulus of the first high-temperature resistant layer 32 is K2, the flexural modulus of the second high-temperature resistant layer 42 is K3, and the flexural modulus of the second covering layer 41 is K4; wherein, K1, K2, K3, and K4 satisfy: K1 > K2 ≥ K3 > K4.
[0102] The melting point of the first coating layer is P1, the melting point of the first high-temperature resistant layer is P2, the melting point of the second high-temperature resistant layer is P3, and the melting point of the second coating layer is P4; wherein, P1, P2, P3, and P4 satisfy: P2>P3≥P1>P4.
[0103] In preparing the sealing ring 3, the high-temperature resistant material raw material is first shaped into a first high-temperature resistant layer 32 of a specific size through sintering, casting, UV curing and other means; then, the outer surface of the first high-temperature resistant layer 32 is shaped into a first covering layer 31 of a specific size through sintering, casting, UV curing and other means, thereby obtaining the structure in which the first covering layer 31 wraps the first high-temperature resistant layer 32, i.e., the sealing ring 3.
[0104] In preparing the upper plastic 4, the high-temperature resistant material raw material is first shaped into a second high-temperature resistant layer 42 of a specific size through sintering, casting, UV curing and other means; then, the outer surface of the first high-temperature resistant layer 32 is shaped into a second covering layer 41 of a specific size through sintering, casting, UV curing and other means, thereby obtaining the structure in which the second covering layer 41 wraps the second high-temperature resistant layer 42, that is, the upper plastic 4.
[0105] During the installation of the cover plate assembly 100, the sealing ring 3 is first fitted onto the outer wall of the column portion 21, then the column portion 21 is installed into the mounting hole 101, and finally the upper plastic 4 is fitted onto the outer wall of the column portion 21. This allows the cover plate 1, the electrode post 2, the sealing ring 3, and the upper plastic 4 to cooperate and seal the mounting hole 101. When the cover plate assembly 100 is fitted with the housing 200, it can close the opening 20 of the housing 200, allowing the electrolyte to be stored inside the housing 200 without overflowing.
[0106] The lower plastic 6 is located below the cover plate 1, and the pole post 2 is located in the through hole of the lower plastic 6. The sealing ring 3 is located between the cover plate 1 and the lower plastic 6. Under the combined action of the cover plate 1 and the lower plastic 6, the sealing ring 3 is fixed at the mounting hole 101.
[0107] This application also provides a battery cell, including a cover assembly. For example... Figure 9 As shown, the battery cell includes a housing 200 and a cover assembly 100. The housing 200 has an opening 20, and the cover assembly 100 is disposed on the housing 200 to close the opening 20.
[0108] Battery cells include, but are not limited to, lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments disclosed herein are not limited to these. Battery packs include battery cells and provide power to electrical devices. Electrical devices can be mobile phones, portable devices, laptops, electric vehicles, electric cars, ships, spacecraft, electric toys, and power tools, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.
[0109] In some embodiments, the battery cell may include the sealing ring having the aforementioned coating layer and high-temperature resistant layer. In some embodiments, the battery cell may include the aforementioned plastic coating having the aforementioned coating layer and high-temperature resistant layer. In some embodiments, the battery cell includes both the aforementioned sealing ring having the aforementioned coating layer and high-temperature resistant layer and the plastic coating having the aforementioned coating layer and high-temperature resistant layer.
[0110] like Figures 10 to 11 As shown, a conventional cover plate assembly 100 is provided, which includes a cover plate 1, a pole post 2, a sealing ring 3, an upper plastic 4, an explosion-proof valve 5, and a lower plastic 6. However, the sealing ring 3 does not have a first high-temperature resistant layer 32 inside, and the upper plastic 4 does not have a second high-temperature resistant layer 42 inside.
[0111] When a battery cell is in an abnormal operating state, such as at extremely high temperatures, the sealing ring, upper plastic, and lower plastic will deform when they reach their softening or melting points. That is, the sealing ring 3, upper plastic 4, and lower plastic 6 are all made of… Figure 11 The molten state in it becomes Figure 10 In this state, the battery loses its insulation and sealing capabilities. If there is residual gas or excessive electrolyte inside the battery cell, it can easily leak from there, leading to battery failure.
[0112] like Figures 7 to 8 As shown, the cover plate assembly 100 provided in this application embodiment has a first high-temperature resistant layer 32 inside the sealing ring 3 and a second high-temperature resistant layer 42 inside the upper plastic 4.
[0113] When a battery cell is in an abnormal operating state, such as at extremely high temperatures, the sealing ring 3, upper plastic 4, and lower plastic 6 will also deform when they reach their softening or melting points. That is, the sealing ring 3, upper plastic 4, and lower plastic 6 are all... Figure 8 The molten state in it becomes Figure 7The compression of the sealing ring 3 decreases or disappears. At this time, the first high-temperature resistant layer 32, which was compressed inside the sealing ring 3, returns to a circular structure, with R1≥D1 and R2≥D2. Due to the tight fit between the sealing ring 3 and the cover plate 1 and the terminal post 2, and between the upper plastic 4 and the cover plate 1 and the terminal post 2, even if there is residual gas or excessive electrolyte in the battery cell, the terminal post seal will not fail.
[0114] Therefore, in this embodiment, a sealing ring 3 is disposed below the cover plate 1, and an upper plastic layer 4 is disposed above the cover plate 1 and extends into the mounting hole 101, thereby sealing the connection between the electrode post 2 and the cover plate 1 (i.e., the location of the mounting hole 101). Furthermore, a first high-temperature resistant layer 32 is disposed within the sealing ring 3, and a second high-temperature resistant layer 42 is disposed within the upper plastic layer 4, enabling the cover plate assembly 100 to seal the mounting hole 101 where the electrode post 2 is located under any temperature conditions, and further improving the sealing reliability of the battery cell under extreme temperatures.
[0115] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0116] The foregoing has provided a detailed description of a cover plate assembly and a battery cell provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A cover plate assembly for a single battery cell, characterized in that, include: A cover plate having mounting holes having intersecting axial and radial directions, the mounting holes penetrating the cover plate along the axial direction; The electrode post is disposed within the mounting hole; and A sealing ring is sleeved axially between the pole and the cover plate. The sealing ring includes a first covering layer and a first high-temperature resistant layer. The first covering layer covers the surface of the first high-temperature resistant layer, and the melting point of the first high-temperature resistant layer is greater than that of the first covering layer.
2. The cover plate assembly for a battery cell according to claim 1, characterized in that, The cover plate has a protruding ring that extends radially into the mounting hole; The pole post includes a column portion and a connecting portion. The column portion passes through the mounting hole, and the connecting portion is connected to one end of the column portion in the axial direction. The sealing ring is disposed axially between the convex ring and the connecting portion, and the connecting portion extends radially and partially overlaps the cover plate in the axial direction.
3. The cover plate assembly for a battery cell according to claim 2, characterized in that, The first high-temperature resistant layer has a ring-shaped structure. In the radial direction, the maximum dimension between the inner wall and the outer wall of the first high-temperature resistant layer is R1; the axial distance between the convex ring and the connecting part is D1. Among them, R1 and D1 satisfy the condition: R1≥D1.
4. The cover plate assembly for a battery cell according to any one of claims 1 to 3, characterized in that, The material used for the first coating layer includes at least one of fluororubber, silicone rubber, and polyolefin. The material used for the first high-temperature resistant layer includes at least one of high-temperature resistant polymers, inorganic substances, and organic-inorganic mixtures.
5. The cover plate assembly for a battery cell according to claim 4, characterized in that, The high-temperature resistant polymer includes at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic material includes at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; the organic-inorganic mixture includes at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
6. The cover plate assembly for a battery cell according to claim 1, characterized in that, The flexural modulus of the first coating layer is K1, and the flexural modulus of the first high-temperature resistant layer is K2, wherein K1 and K2 satisfy: K1 > K2.
7. A cover plate assembly for a single battery cell, characterized in that, include: A cover plate having mounting holes having intersecting axial and radial directions, the mounting holes penetrating the cover plate along the axial direction; A pole post, wherein the pole post is disposed within the mounting hole; as well as An upper plastic is provided on the cover plate, and a portion of the upper plastic extends into the mounting hole and is disposed in the radial direction between the pole post and the cover plate; The plastic portion includes a second coating layer and a second high-temperature resistant layer. The second coating layer covers the surface of the second high-temperature resistant layer, and the melting point of the second high-temperature resistant layer is greater than that of the second coating layer.
8. The cover plate assembly for a battery cell according to claim 7, characterized in that, The cover plate has a protruding ring that extends radially into the mounting hole; The upper plastic includes a first part and a second part connected together, the second part being connected to the first part in the axial direction, wherein the first part is disposed in the radial direction between the convex ring and the pole post, and the second part is located on the convex ring; wherein the first part includes a second covering layer and a second high-temperature resistant layer.
9. The cover plate assembly for a battery cell according to claim 8, characterized in that, The second high-temperature resistant layer is a ring structure. In the radial direction, the maximum dimension between the inner wall and the outer wall of the second high-temperature resistant layer is R2. In the radial direction, the distance between the outer wall of the pole post and the convex ring is D2. Wherein, R2 and D2 satisfy: R2≥D2.
10. The cover assembly for a battery cell according to any one of claims 7 to 9, characterized in that, The material used for the second coating layer includes at least one of polypropylene, polyethylene, polyimide, and conductive polypropylene; The material used for the second high-temperature resistant layer includes at least one of high-temperature resistant polymers, inorganic substances, and organic-inorganic mixtures.
11. The cover plate assembly for a battery cell according to claim 10, characterized in that, The high-temperature resistant polymer includes at least one of polyetheretherketone, aramid, polyimide, and polytetrafluoroethylene; the inorganic material includes at least one of non-metallic elements and their oxides, metallic elements and their oxides, alloys, and ceramics; the organic-inorganic mixture includes at least one of ceramic resin mixtures and mixtures of metals and their oxides with resins.
12. The cover plate assembly for a battery cell according to claim 7, characterized in that, The flexural modulus of the second high-temperature resistant layer is K3, and the flexural modulus of the second coating layer is K4; wherein, K3 and K4 satisfy: K3 > K4.
13. A cover plate assembly for a battery cell, characterized in that, include: A cover plate having mounting holes having intersecting axial and radial directions, the mounting holes penetrating the cover plate along the axial direction; A pole post, wherein the pole post is disposed within the mounting hole; A sealing ring is sleeved axially between the pole and the cover plate. The sealing ring includes a first covering layer and a first high-temperature resistant layer. The first covering layer covers the surface of the first high-temperature resistant layer. The melting point of the first high-temperature resistant layer is greater than that of the first covering layer. An upper plastic insert is disposed on the side of the cover plate away from the sealing ring, a portion of which extends into the mounting hole and is positioned radially between the pole post and the cover plate; and The plastic portion includes a second coating layer and a second high-temperature resistant layer. The second coating layer covers the surface of the second high-temperature resistant layer, and the melting point of the second high-temperature resistant layer is greater than that of the second coating layer.
14. The cover plate assembly for a battery cell according to claim 13, characterized in that, The cover plate has a protruding ring that extends radially into the mounting hole; The pole post includes a column portion and a connecting portion. The column portion passes through the mounting hole, and the connecting portion is connected to one end of the column portion in the axial direction. The sealing ring is disposed axially between the convex ring and the connecting portion, and the connecting portion extends radially and partially overlaps the cover plate in the axial direction.
15. The cover plate assembly for a battery cell according to claim 14, characterized in that, The upper plastic includes a first part and a second part connected together, the second part being connected to the first part in the axial direction, wherein the first part is radially disposed between the convex ring and the pole post, and the second part is located on the convex ring; The first part includes the second coating layer and the second high-temperature resistant layer.
16. The cover plate assembly for a battery cell according to claim 14, characterized in that, The first high-temperature resistant layer has a ring-shaped structure. In the radial direction, the maximum dimension between the inner wall and the outer wall of the first high-temperature resistant layer is R1; the axial distance between the convex ring and the connecting part is D1. Among them, R1 and D1 satisfy the following condition: R1≥D1; The second high-temperature resistant layer is a ring structure. In the radial direction, the maximum dimension between the inner wall and the outer wall of the second high-temperature resistant layer is R2. In the radial direction, the distance between the outer wall of the pole post and the convex ring is D2. Wherein, R2 and D2 satisfy: R2≥D2.
17. The cover plate assembly for a battery cell according to claim 13, characterized in that, The flexural modulus of the first coating layer is K1, the flexural modulus of the first high-temperature resistant layer is K2, the flexural modulus of the second high-temperature resistant layer is K3, and the flexural modulus of the second coating layer is K4; wherein, K1, K2, K3, and K4 satisfy: K1>K2≥K3>K4.
18. The cover assembly for a battery cell according to any one of claims 13 to 15, characterized in that, The melting point of the first coating layer is P1, the melting point of the first high-temperature resistant layer is P2, the melting point of the second high-temperature resistant layer is P3, and the melting point of the second coating layer is P4. Among them, P1, P2, P3, and P4 satisfy: P2 > P3 ≥ P1 > P4.
19. A single battery cell, characterized in that, include: The shell has an opening; as well as The cover assembly as claimed in any one of claims 1 to 18, wherein the cover assembly is disposed in the housing for closing the opening.