CN219457802U - Cover plate of lithium battery and battery pack - Google Patents

Abstract

The application relates to a apron and battery package of lithium cell, wherein the apron of lithium cell includes at least: the cover plate body is provided with a pressure relief hole; the explosion-proof piece is arranged on one side surface of the cover plate body and covers the pressure relief hole; the first protection film is attached to one side surface of the explosion-proof piece, facing the cover plate body, and covers the explosion-proof piece, and the first protection film is used for blocking the explosion-proof piece from being contacted with electrolyte of the lithium battery. Through install the explosion proof piece on the one side surface of apron body, and be in the explosion proof piece orientation laminating first protection film on the one side surface of apron body, and then separation explosion proof piece with lithium cell's electrolyte contact, this application can form the inoxidizing coating of electrolyte resistant between explosion proof piece and electrolyte, reduces the corruption risk of explosion proof piece, promotes lithium cell's security, simultaneously because simple structure, has further reduced lithium cell's cost.

Description

Cover plate of lithium battery and battery pack

Technical Field

The application relates to the technical field of batteries, in particular to a cover plate of a lithium battery and a battery pack.

Background

At present, a lithium battery is generally composed of a battery core, a cover plate and a shell for wrapping the battery core, wherein an anode, a cathode, electrolyte and a diaphragm positioned between the anode and the cathode are arranged in the battery core, and the electrolyte is generally composed of lithium salt and an organic solvent. When the battery core is abnormal, a large amount of gas is generated in the battery, so that the internal pressure of the battery is increased sharply, and the battery is exploded, thereby causing safety accidents.

In the related art, in order to increase the explosion-proof function, an explosion-proof sheet is generally disposed on a cover plate of a lithium battery, so that the safety protection of the battery cell is enhanced by using the explosion-proof sheet. However, in the standing stage of the battery cell after the completion of liquid injection, the electrolyte can be contacted with one side of the explosion-proof piece, which is close to the pole piece. Because the explosion-proof sheet contacts the electrolyte for a long time, under the condition that the electrolyte contains conductive particles (such as metal particles), the explosion-proof valve is easy to corrode, and potential safety hazards are caused. In addition, the perimeter of the rupture disc is usually scored, and the material layer at the scored location of the rupture disc is too thin, especially susceptible to corrosion, further reducing the safety of the battery.

Disclosure of Invention

In view of this, this application provides a apron and battery package of lithium cell, can form the inoxidizing coating of resistant electrolyte between explosion-proof piece and electrolyte, reduces the corruption risk of explosion-proof piece, promotes the security of lithium cell, simultaneously because simple structure, has further reduced the cost of lithium cell.

In a first aspect, embodiments of the present application provide a cover plate of a lithium battery, the cover plate of the lithium battery at least including: the cover plate body is provided with a pressure relief hole; the explosion-proof piece is arranged on one side surface of the cover plate body, facing the electrolyte of the lithium battery, and covers the pressure relief hole; the first protection film is attached to one side surface of the explosion-proof piece, which is away from the cover plate body, and covers the explosion-proof piece, and the first protection film is used for blocking the explosion-proof piece from being contacted with electrolyte of the lithium battery.

In an embodiment, the explosion-proof sheet includes a first bending portion, a second bending portion, a first connecting portion and a second connecting portion, wherein the first connecting portion is used for connecting one end of the first bending portion and one end of the second bending portion, and the second connecting portion is used for connecting the other end of the first bending portion and the other end of the second bending portion.

In an embodiment, the explosion-proof sheet further includes a bottom surface and a stepped structure formed by the bottom surface and the first bending portion, the second bending portion, the first connecting portion and the second connecting portion, respectively.

In an embodiment, the cover plate of the lithium battery further comprises an insulating bracket, and the insulating bracket is arranged on one side of the cover plate body, which faces the first protective film.

In an embodiment, the insulating support is provided with a lower plastic component and a plurality of weight reduction grooves respectively arranged on two sides of the lower plastic component, the lower plastic component is arranged in the middle of the insulating support, and the weight reduction grooves are used for reducing the weight of the insulating support.

In an embodiment, the cover plate body is provided with a first liquid injection hole positioned at one side of the pressure relief hole, the insulating support is provided with a second liquid injection hole, and the second liquid injection hole is matched with the first liquid injection hole and is used for injecting electrolyte into the cavity of the lithium battery.

In an embodiment, the cover plate of the lithium battery further comprises a positive electrode sleeve member and a negative electrode sleeve member which are respectively arranged at two ends of the cover plate body, a positive electrode sleeve member hole penetrating through the positive electrode sleeve member is formed in the middle of the positive electrode sleeve member, and a negative electrode sleeve member hole penetrating through the negative electrode sleeve member is formed in the middle of the negative electrode sleeve member.

In an embodiment, the cover plate of the lithium battery further includes a first upper plastic and a second upper plastic, wherein the first upper plastic is disposed directly above the positive electrode sleeve, and the second upper plastic is disposed directly above the negative electrode sleeve.

In an embodiment, the cover plate of the lithium battery further comprises a second protective film, wherein the second protective film is attached to one side of the pressure release hole, which is away from the explosion-proof piece, and covers the explosion-proof piece.

In a second aspect, embodiments of the present application provide a battery pack including a cover plate of the lithium battery.

Through install the explosion proof piece on the one side surface of apron body, and be in the explosion proof piece orientation laminating first protection film on the one side surface of apron body, and then separation explosion proof piece with lithium cell's electrolyte contact, according to the aspect of this application can form the inoxidizing coating of electrolyte resistant between explosion proof piece and electrolyte, reduce the corruption risk of explosion proof piece, promote lithium cell's security, simultaneously because simple structure, further reduced lithium cell's cost.

Drawings

Technical solutions and other advantageous effects of the present application will be made apparent from the following detailed description of specific embodiments of the present application with reference to the accompanying drawings.

Fig. 1 shows an exploded schematic view of a cover plate of a lithium battery according to an embodiment of the present application.

Fig. 2 shows a schematic perspective view of the rupture disc according to an embodiment of the present application.

Fig. 3 shows an enlarged partial cross-sectional schematic view of a rupture disc of an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

In the description of the present application, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," etc. indicate or are based on the orientation or positional relationship shown in the drawings, merely for convenience of description and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically connected, electrically connected or can be communicated with each other; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements or interaction relationship between the two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

The following disclosure provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. Furthermore, the present application may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not in themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize the application of other processes and/or the use of other materials. In some instances, methods, means, elements, and circuits have not been described in detail as not to unnecessarily obscure the present application.

Fig. 1 shows an exploded schematic view of a cover plate of a lithium battery according to an embodiment of the present application. As shown in fig. 1, the cover plate of the lithium battery may include at least a cover plate body 1, a rupture disc 2, and a first protection film 3. Wherein, the cover plate body 1 can be made of aluminum sheet. Because the texture of aluminium is soft, and ductility is good, adopts the aluminium sheet to make apron body 1 for apron body 1 can bear the deformation of certain degree, promotes the ductility of apron body 1, simultaneously because aluminium's density is little, makes the quality of aluminium sheet lighter, can lighten the weight of whole apron. Illustratively, the outer edge of the cover body 1 may be rectangular in shape.

In an embodiment, referring to fig. 1, the cover body 1 may be provided with a pressure relief hole 11. The pressure relief hole 11 may be a oval shape and penetrates the cover body 1 along the direction of the cover body 1 toward the rupture disc 2. The explosion-proof sheet 2 may be mounted on a side surface of the cap plate body 1 facing the electrolyte of the lithium battery, and covers the pressure relief hole 11. Specifically, the explosion-proof sheet 2 is mounted on a side surface of the cover plate body 1 facing away from the second protective film 9, and an outer edge of the explosion-proof sheet 2 is arranged in a waist-round shape. The length of the rupture disc 2 in a first direction (i.e. the x-direction of the cartesian coordinate system in fig. 1) is greater than the width of the rupture disc 2 in a second direction (i.e. the x-direction of the cartesian coordinate system in fig. 1). The thickness of the rupture disc 2 may be set as desired along the third direction (i.e., the z-direction of the cartesian coordinate system in fig. 1), which is not limited in this regard.

In an embodiment, the peripheral edge portion of the explosion-proof sheet 2 may be attached to the annular inner wall of the pressure relief hole 11, so that the explosion-proof sheet 2 is firmly connected with the cover plate body 1 by welding, so as to ensure that the explosion-proof sheet 2 can completely cover the pressure relief hole 11. It should be noted that, since the rupture disk 2 is ruptured when the internal pressure of the lithium battery exceeds a preset threshold value and is sealed in a normal state, the function is similar to a valve or a switch, the rupture disk 2 may also be referred to as an explosion-proof valve in this application.

Fig. 2 shows a schematic perspective view of the rupture disc 2 according to an embodiment of the present application. Referring to fig. 2, the rupture disc 2 may include a first bending portion 21, a second bending portion 22, a first connecting portion 23, and a second connecting portion 24. The first connecting portion 23 may be used to connect one end of the first bending portion 21 and one end of the second bending portion 22, and the second connecting portion 24 may be used to connect the other end of the first bending portion 21 and the other end of the second bending portion 22. The first bending portion 21, the second bending portion 22, the first connecting portion 23, and the second connecting portion 24 may be integrally formed.

In an embodiment, the first bending portion 21 and the second bending portion 22 may be both arc-shaped. The first bending portion 21 and the second bending portion 22 are both arc-shaped. The first connecting portion 23 and the second connecting portion 24 may be disposed along the first direction and symmetrical with respect to a symmetrical center line of the rupture disc 2 along the first direction. The first bending portion 21 and the second bending portion 22 are symmetrical with respect to a symmetry center line of the rupture disc 2 along the second direction.

In an embodiment, the explosion-proof sheet 2 may be a sunken structure with a concave middle portion. Referring to fig. 2, specifically, the rupture disc 2 may further include a bottom surface 25 and a stepped structure formed by the bottom surface 25 and the first bent portion 21, the second bent portion 22, the first connecting portion 23, and the second connecting portion 24, respectively. For example, for the first connecting portion 23, a stepped structure is provided between the first connecting portion 23 and the bottom surface 25, and the stepped structure is similar to a court stand, and can be used to more tightly fit the rupture disc 2 with the pressure release hole 11.

Fig. 3 shows an enlarged partial cross-sectional schematic view of the rupture disc 2 of an embodiment of the present application. As shown in fig. 3, corresponding to the partially enlarged structure 20 in fig. 2, taking the first connection portion 23 as an example, the first step 202 may be disposed at a lower position adjacent to the top surface 201 of the first connection portion 23. By analogy, a second step 204 may be provided below the bottom surface 203 of the first step 202, and a third step 206 may be provided below the bottom surface 205 of the second step 204. The bottom surface of the third step 206 may be flush with the bottom surface 25 of the rupture disc 2. That is, the stepped structure in fig. 2 may be a three-stage stepped structure.

It is noted that in fig. 3, the first step 202, the second step 204, and the third step 206 are parallel to each other and all disposed along the third direction, and the top surface 201, the bottom surface 203, and the bottom surface 205 are parallel to each other and all disposed along the second direction. That is, the first step 202 may be perpendicular to the top surface 201, the bottom surface 203, and the bottom surface 205, respectively, the second step 204 may be perpendicular to the top surface 201, the bottom surface 203, and the bottom surface 205, respectively, and the third step 206 may be perpendicular to the top surface 201, the bottom surface 203, and the bottom surface 205, respectively.

In one embodiment, the first step 202, the second step 204, and the third step 206 extend along the second direction by different lengths. Illustratively, the first step 202, the second step 204, and the third step 206 extend in the second direction with decreasing lengths. In addition, the thicknesses of the first step 202, the second step 204, and the third step 206 in the third direction are also different. The thicknesses of the first step 202, the second step 204, and the third step 206 in the third direction decrease in order.

Through set up step structure in explosion-proof piece 2 to the length and the thickness that each step in the step setting step structure extended, this application embodiment can make explosion-proof piece 2 and pressure release hole 11 agree with each other, and then makes explosion-proof piece 2 and pressure release hole 11 inseparabler cooperation, in time dredge the pressure release route when exceeding preset threshold value in the battery of being convenient for, reduces the security risk that explosion-proof piece 2 burst and cause.

With continued reference to fig. 1, the cover plate of the lithium battery further includes a first protection film 3. The first protection film 3 can be attached to the surface of one side, away from the cover plate body 1, of the explosion-proof sheet 2 and cover the explosion-proof sheet 2, and the first protection film 3 can be used for blocking the explosion-proof sheet 2 from being contacted with electrolyte of the lithium battery.

In one example, the thickness of the first protective film 3 may be set between 0.01mm and 1 mm. Preferably, the thickness of the first protective film 3 may be 0.03mm.

In an embodiment, the first protective film 3 may be made of polyester resin (Polyethylene terephthalate, PET). Through adopting polyester resin preparation the protection film, the embodiment of the application can make the protection film possess the characteristic that electrolyte is non-wetting, and then separation explosion-proof piece 2 with lithium cell's electrolyte direct contact forms the protective layer in order to reduce explosion-proof piece 2 by the risk of corruption.

In an embodiment, as shown in fig. 1, a second protection film 9 may be further disposed on a side of the pressure relief hole 11 facing away from the explosion protection sheet 2, where the second protection film 9 and the pressure relief hole 11 are disposed in a matching manner on a side facing away from the explosion protection sheet 2. The second protective film 9 has a kidney-shaped structure, and can be attached to the side of the pressure release hole 11 facing away from the rupture disc 2.

Further, the first protective film 3 and the second protective film 9 may be disposed on two sides of the cover body 1. The second protection film 9 is attached to one side of the pressure relief hole 11, which is away from the explosion-proof sheet 2, and covers the explosion-proof sheet 2. Since the second protective film 9 may not be in direct contact with the electrolyte, the material used for the second protective film 9 may be different from the material used for the first protective film 3. It will be appreciated that the material used for the second protective film 9 may be selected according to actual needs, and is not limited in this application.

Referring to fig. 1, the positive electrode assembly 41 and the negative electrode assembly 42 may be further separated at both ends of the cap body 1, and both outer edges of the positive electrode assembly 41 and the negative electrode assembly 42 may be rectangular. The middle position of the positive electrode assembly 41 may be provided with a positive electrode assembly hole 411 penetrating the positive electrode assembly, and the middle position of the negative electrode assembly 42 may be provided with a negative electrode assembly hole 421 penetrating the negative electrode assembly. Illustratively, the positive electrode assembly holes 41 and the negative electrode assembly holes 42 are both circular. The positive electrode sleeve 41 and the negative electrode sleeve 42 are attached to the surface of the cover plate body 1 on the side facing away from the explosion-proof sheet 2.

In an embodiment, a first cover body 1 hole of the cover body 1 is formed at a position corresponding to the positive electrode sleeve hole 411 on the cover body 1, and a second cover body 1 hole of the cover body 1 is formed at a position corresponding to the negative electrode sleeve hole 421 on the cover body 1. The first cover plate body 1 hole is matched with the positive electrode sleeve hole 411, and the second cover plate body 1 hole is matched with the negative electrode sleeve hole 421. The first cover body 1 hole and the second cover body 1 hole are circular, the diameter of the first cover body 1 hole is equal to the diameter of the positive electrode sleeve hole 411, and the diameter of the second cover body 1 hole is equal to the diameter of the negative electrode sleeve hole 421.

Further, the cover plate of the lithium battery may further include an insulating bracket 5, and the insulating bracket 5 is disposed on a side of the cover plate body 1 facing the first protective film 3. The outer edge of the insulating support 5 may be rectangular, and may be engaged with the outer edge of the cover body 1. The two ends of the insulating support 5 may be separately provided with a first support sleeve 51 and a second support sleeve 52, the outer edge of the first support sleeve 51 may be rectangular and arc-shaped, and the shape of the second support sleeve 52 may be the same as the shape of the first support sleeve 51. A first bracket set hole 511 penetrating the first bracket set may be further provided at the junction of the rectangle and the arc of the first bracket set 51, and correspondingly, a second bracket set hole 521 penetrating the second bracket set may be further provided at the junction of the rectangle and the arc of the second bracket set 52. Illustratively, the first bracket set aperture 511 and the second bracket set aperture 521 are both circular. The first bracket set 51 and the second bracket set 52 are attached to the surface of the insulating bracket 5 on the side facing the first protective film 3.

In an embodiment, a first insulating bracket hole of the insulating bracket 5 is formed at a position corresponding to the first bracket set hole 511 on the insulating bracket 5, and a second insulating bracket hole of the insulating bracket 5 is formed at a position corresponding to the second bracket set hole 521 on the insulating bracket 5. The first bracket set hole 511 is adapted to the first insulating bracket hole and the second bracket set hole 521 is adapted to the second insulating bracket hole. Illustratively, the first insulating support hole and the second insulating support hole are circular, the diameter of the first insulating support hole is equal to the diameter of the first support sleeve hole 511, and the diameter of the second insulating support hole is equal to the diameter of the second support sleeve hole 521.

In an embodiment, the insulating support 5 may further be provided with a plurality of weight-reducing grooves 53. The specific size of the weight-reducing groove 53 may be set according to actual needs. For example, when the weight of the insulating holder 5 is excessively heavy, the entire weight of the insulating holder 5 can be further reduced by increasing the groove depth of the weight-reducing groove 53.

In an embodiment, a lower plastic component 54 may be further disposed on the insulating support 5, and the lower plastic component 54 may be disposed in a middle portion of the insulating support 5. For example, the lower plastic component 54 has a rectangular structure, and the plurality of weight-reducing grooves 53 may be formed on two sides of the lower plastic component 54.

Further, the cover plate body 1 is provided with a first liquid injection hole 13, and the insulating support 5 is provided with a second liquid injection hole 55. The first liquid injection hole 13 is located between the pressure release hole 11 and the positive electrode sleeve 41, and the second liquid injection hole 55 is located at the edge joint of the four weight reduction grooves. The second filling hole 55 is arranged in cooperation with the first filling hole 13. Illustratively, the second injection hole 55 and the first injection hole 13 are both circular, and the diameter of the second injection hole 55 is the same as that of the first injection hole 13 so as to inject the electrolyte into the cavity of the lithium battery case through the first injection hole 13 and the second injection hole 55.

With continued reference to fig. 1, the cover plate of the lithium battery may further include a first upper plastic 61 and a second upper plastic 62, wherein the first upper plastic 61 is disposed directly above the positive electrode assembly 41, and the second upper plastic 62 is disposed directly above the negative electrode assembly 42. The first upper plastic 61 may be provided with a first upper plastic hole 611, and the second upper plastic 62 may be provided with a second upper plastic hole 621.

In an embodiment, the cap plate of the lithium battery may further include a first terminal block 71 and a second terminal block 72. The first terminal block 71 is disposed directly above the first upper plastic 61, and the second terminal block 72 is disposed directly above the second upper plastic 62. The first terminal block 71 may be provided with a first terminal block hole 711, and the second terminal block 72 may be provided with a second terminal block hole 721.

In an embodiment, the cover plate of the lithium battery may further include a positive electrode post 81 and a negative electrode post 82. Illustratively, the first terminal press block hole 711, the first upper plastic hole 611, the positive electrode sleeve hole 411, the first cover plate body 1 hole, the first bracket sleeve hole 511, and the first insulating bracket hole have the same size, so that the positive electrode post 81 sequentially passes through a side of the insulating bracket 5 facing away from the cover plate body 1. Similarly, the second terminal pressing block hole 721, the second upper plastic hole 621, the negative electrode sleeve hole 421, the second cover plate body 1 hole, the second bracket sleeve hole 521 and the second insulating bracket hole have the same size, so that the negative electrode post 82 sequentially passes through the side of the insulating bracket 5 facing away from the cover plate body 1. The top cap of the positive electrode post 81 and the top cap of the negative electrode post 82 may be disposed on a side facing away from the insulating support 5, so that the top caps of the positive electrode post 81 and the negative electrode post 82 are fixedly mounted on a surface of the insulating support 5 on a side facing away from the cap plate body 1.

To sum up, through install explosion-proof piece 2 on the one side surface of apron body 1, and be in explosion-proof piece 2 orientation laminate first protection film 3 on the one side surface of apron body 1, and then separation explosion-proof piece 2 with lithium cell's electrolyte contact, this application embodiment can form the inoxidizing coating of electrolyte resistant between explosion-proof piece 2 and electrolyte, reduces explosion-proof piece 2's corrosion risk, promotes lithium cell's security, simultaneously because simple structure, has further reduced lithium cell's cost.

Further, embodiments of the present application provide a battery pack including the cover plate of the lithium battery. It will be appreciated that the specific application scenario of the battery is not limited in this application.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.

The above describes the cover plate and the battery pack of the lithium battery provided by the embodiment of the present application in detail, and specific examples are applied to describe the principle and the implementation of the present application, and the description of the above examples is only used for helping to understand the technical scheme and the core idea of the present application; those of ordinary skill in the art will appreciate that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. A cover plate for a lithium battery, the cover plate comprising at least:

the cover plate comprises a cover plate body (1), wherein a pressure relief hole (11) is formed in the cover plate body (1);

the explosion-proof piece (2) is arranged on one side surface of the cover plate body (1) facing the electrolyte of the lithium battery and covers the pressure relief hole (11);

the lithium battery cover comprises a cover plate body (1), a first protection film (3), wherein the first protection film (3) is attached to one side surface of the explosion-proof sheet (2) away from the cover plate body (1) and covers the explosion-proof sheet (2), and the first protection film (3) is used for blocking the explosion-proof sheet (2) from being contacted with electrolyte of the lithium battery.

2. The cover plate of a lithium battery according to claim 1, wherein the explosion-proof sheet (2) comprises a first bending part (21), a second bending part (22), a first connecting part (23) and a second connecting part (24), the first connecting part (23) is used for connecting one end of the first bending part (21) and one end of the second bending part (22), and the second connecting part (24) is used for connecting the other end of the first bending part (21) and the other end of the second bending part (22).

3. The cover plate of a lithium battery according to claim 2, wherein the explosion-proof sheet further comprises a bottom surface (25) and a step structure formed by the bottom surface (25) and the first bending part (21), the second bending part (22), the first connecting part (23) and the second connecting part (24), respectively.

4. The cover plate of a lithium battery according to claim 1, further comprising an insulating support (5), the insulating support (5) being arranged at a side of the cover plate body (1) facing the first protective film (3).

5. The cover plate of a lithium battery according to claim 4, wherein a lower plastic component (54) and a plurality of weight-reducing grooves (53) respectively arranged on two sides of the lower plastic component (54) are arranged on the insulating support (5), the lower plastic component (54) is arranged in the middle of the insulating support (5), and the weight-reducing grooves (53) are used for reducing the weight of the insulating support (5).

6. The cover plate of a lithium battery according to claim 4, wherein a first liquid injection hole (13) located at one side of the pressure relief hole (11) is formed in the cover plate body (1), a second liquid injection hole (55) is formed in the insulating support (5), and the second liquid injection hole (55) is matched with the first liquid injection hole (13) and is used for injecting electrolyte into a cavity of the lithium battery.

7. The cover plate of a lithium battery according to any one of claims 1-6, further comprising a positive electrode sleeve (41) and a negative electrode sleeve (42) which are respectively arranged at two ends of the cover plate body (1), wherein a positive electrode sleeve hole (411) penetrating through the positive electrode sleeve is arranged at the middle position of the positive electrode sleeve (41), and a negative electrode sleeve hole (421) penetrating through the negative electrode sleeve is arranged at the middle position of the negative electrode sleeve (42).

8. The cover plate of a lithium battery according to any one of claims 1-6, further comprising a first upper plastic (61) and a second upper plastic (62), the first upper plastic (61) being disposed directly above the positive electrode assembly (41), the second upper plastic (62) being disposed directly above the negative electrode assembly (42).

9. The cover plate of a lithium battery according to any one of claims 1-6, further comprising a second protective film (9), wherein the second protective film (9) is attached to the side of the pressure relief hole (11) facing away from the rupture disc (2) and covers the rupture disc (2).

10. A battery pack comprising the cover sheet of a lithium battery according to any one of claims 1 to 9.