CN212571164U - Lithium battery top cap and lithium cell - Google Patents

Abstract

The utility model relates to the field of batteries, in particular to a lithium battery top cover and a lithium battery; the lithium battery top cover comprises a top cover body and a convex hull, wherein the top cover body is provided with a first surface facing the inside of the shell and a second surface facing the outside of the shell, the top cover body is provided with a liquid injection hole, the convex hull is connected with the first surface, and the convex hull is provided with a cavity communicated with the liquid injection hole; a first matching surface and a second matching surface are arranged on one side of the convex hull, which is far away from the first surface, and the distance between the first matching surface and the first surface is smaller than the distance between the second matching surface and the first surface; when the pole lug of the lithium battery is in contact with the second matching surface, the second matching surface can prevent the pole lug from being in contact with the first matching surface, so that a gap is formed between the pole lug and the convex hull, and the liquid injection hole is prevented from being blocked by the pole lug. Be provided with the lithium cell of this lithium cell top cap can be when carrying out the gas tightness and detect, avoid the utmost point ear of lithium cell to block up the notes liquid hole of lithium cell top cap, and then ensure the accuracy that the gas tightness detected to improve detection efficiency.

Description

Lithium battery top cap and lithium cell

Technical Field

The utility model relates to a battery field particularly, relates to a lithium cell top cap and lithium cell.

Background

The secondary lithium ion battery provided by the related art is widely applied to industrial production. Due to the use safety requirement of the battery, the air tightness of the battery needs to be strictly ensured; for the aluminum-shell lithium ion battery, generally, helium is introduced into the battery, and the battery is vacuumized outside the battery, so that a pressure difference is formed between the inside and the outside of the battery, and if the air tightness of the battery does not meet the requirement (namely, a gap exists in the battery structure), the helium diffuses from the inside of the battery to a detection cavity outside the battery through the gap under the action of the pressure difference, so that the air tightness of the battery is detected and fed back by an inductor.

In the positive pressure helium detection process of battery manufacturers in the current market, the inside of a battery and a detection cavity are firstly vacuumized, and then helium is charged into the battery.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a lithium cell top cap and lithium cell, it can be carrying out the gas tightness to the lithium cell and examine time measuring, avoids the utmost point ear of lithium cell to block up the notes liquid hole of lithium cell top cap, and then ensures the accuracy that the gas tightness detected to improve detection efficiency.

The embodiment of the utility model is realized like this:

in a first aspect, an embodiment of the present invention provides a lithium battery top cover for being disposed on a casing of a lithium battery, the lithium battery top cover comprising a top cover body and a convex hull, the top cover body having a first surface facing the inside of the casing and a second surface facing the outside of the casing, the top cover body having a liquid injection hole, the convex hull being connected to the first surface, and the convex hull having a cavity communicated with the liquid injection hole; a first matching surface and a second matching surface are arranged on one side of the convex hull, which is far away from the first surface, and the distance between the first matching surface and the first surface is smaller than the distance between the second matching surface and the first surface; when the pole lug of the lithium battery is in contact with the second matching surface, the second matching surface can prevent the pole lug from being in contact with the first matching surface, so that a gap is formed between the pole lug and the convex hull, and the liquid injection hole is prevented from being blocked by the pole lug.

In an alternative embodiment, the first mating surface and the second mating surface are stepped along a direction perpendicular to the first surface.

In an optional embodiment, the convex hull comprises a first half round table and a second half round table which are connected with each other, one side of the first half round table and one side of the second half round table are both connected with the first surface, and the first half round table and the second half round table are spliced to form a cavity; along the direction of the first surface of perpendicular to, the height that highly is less than the second half round platform of first half round platform, and one side that first half round platform deviates from the first surface is first fitting surface, and one side that the second half round platform deviates from the first surface is the second fitting surface.

In an optional implementation manner, one side of the convex hull, which deviates from the first surface, is provided with a limiting surface, the extending surface where the limiting surface is located and the first surface are arranged at an included angle, and the first matching surface and the second matching surface are both arranged on the limiting surface.

In an optional embodiment, the convex hull comprises a first boss and a second boss, one side of the first boss and one side of the second boss are both connected with the first surface, the first boss is provided with a cavity, one side of the first boss departing from the first surface is provided with a first fitting surface, and one side of the second boss departing from the first surface is provided with a second fitting surface.

In an alternative embodiment, the second boss is located within the cavity.

In an alternative embodiment, the boss is located outside the cavity.

In an alternative embodiment, the cavity is circular in cross-section in a direction parallel to the first face, and the second boss extends radially of the cavity.

In an alternative embodiment, the convex hull comprises a plurality of second bosses, which are distributed along the circumference of the first boss.

In a second aspect, an embodiment of the present invention provides a lithium battery, including the lithium battery top cap of any one of the foregoing embodiments.

The utility model discloses lithium battery top cap's beneficial effect includes: the embodiment of the utility model provides a lithium battery top cap can set up on the casing of lithium cell, this lithium cell top cap includes top cap body and convex closure, the top cap body has the first face towards the casing inside and the second face towards the casing outside, the top cap body has seted up annotates the liquid hole, annotate the liquid hole and be used for annotating liquid when assembling the lithium cell, and bleed and fill into helium when detecting the gas tightness of lithium cell, the convex closure is connected with the first face, and the convex closure has the cavity with annotating the liquid hole intercommunication; a first matching surface and a second matching surface are arranged on one side of the convex hull, which is far away from the first surface, and the distance between the first matching surface and the first surface is smaller than the distance between the second matching surface and the first surface; when the pole lug of the lithium battery is contacted with the second matching surface, the second matching surface can prevent the pole lug from being contacted with the first matching surface, so that a gap is formed between the pole lug and the convex hull, and the liquid injection hole is prevented from being blocked by the pole lug; so, carry out the gas tightness to the lithium cell that is provided with this lithium cell top cap and detect (helium is examined), and through annotating the liquid hole evacuation, make the utmost point ear of lithium cell remove under the effect of negative pressure when contacting with the convex closure, can make utmost point ear and second fitting surface contact, in order to utilize the second fitting surface to block utmost point ear and first fitting surface contact, in order to make and form the clearance between utmost point ear and the convex closure, in order to prevent to annotate the liquid hole and blockked up by utmost point ear, can be in order to ensure that the notes liquid hole that is the route of evacuation is not blockked up, ensure the smooth development of evacuation, and then avoid the termination of testing procedure, in order to improve the detection precision.

The utility model discloses beneficial effect of lithium cell includes: the utility model discloses the lithium cell includes foretell lithium cell roof, it can detect (helium is examined) carrying out the gas tightness, through annotating liquid hole evacuation, make the utmost point ear of lithium cell remove under the effect of negative pressure to when contacting with the convex closure, make utmost point ear and second fitting surface contact, and utilize the second fitting surface to block utmost point ear and first fitting surface contact, so that form the clearance between utmost point ear and the convex closure, in order to prevent to annotate the liquid hole and blockked up by utmost point ear, can be in order to ensure that the notes liquid hole of the route as the evacuation is not blockked up, ensure developing smoothly of evacuation, and then avoid the termination of testing procedure, in order to improve the detection precision, and improve detection efficiency.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic structural diagram of a top cover of a lithium battery in an embodiment of the present invention;

FIG. 2 is an enlarged view taken at II in FIG. 1;

fig. 3 is a schematic structural diagram of a top cover of a lithium battery in an embodiment of the present invention;

FIG. 4 is an enlarged view taken at IV in FIG. 3;

fig. 5 is a schematic structural diagram of a top cover of a lithium battery in an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a top cover of a lithium battery in an embodiment of the present invention;

FIG. 7 is an enlarged view taken at VI in FIG. 6;

fig. 8 is a schematic structural diagram of a top cover of a lithium battery in an embodiment of the present invention;

fig. 9 is a sixth schematic structural view of a top cover of a lithium battery in an embodiment of the present invention;

FIG. 10 is an enlarged view of the X in FIG. 9.

Icon: 010-lithium battery top cover; 100-a top cover body; 200-convex hull; 110-liquid injection hole; 210-a cavity; 101-a first side; 102-a second face; 221-a first mating face; 222-a second mating surface; 231-a first half round table; 232-a second half-truncated cone; 240-a limiting surface; 251-a first boss; 252-a second boss.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "inside" and "outside" are used for indicating the position or positional relationship based on the position or positional relationship shown in the drawings, or the position or positional relationship that the utility model is usually placed when using, and are only for convenience of describing the present invention and simplifying the description, but not for indicating or implying that the device or element to be referred must have a specific position, be constructed and operated in a specific position, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The embodiment provides a lithium battery which has wide application in the fields of mobile phones, unmanned planes, electric vehicles and the like.

Because the safety in utilization of battery requires, need strictly guarantee the gas tightness of battery, so all need carry out helium to the lithium cell and examine (gas tightness detects) usually, detect the flow and roughly include: and if the air tightness of the battery does not meet the requirement (namely, a gap exists in the battery structure), the helium gas is diffused to the detection cavity outside the battery from the inside of the battery through the gap under the action of the pressure difference, so that the air tightness of the battery is detected and fed back by the sensor.

However, in the process of helium detection of the lithium battery provided by the related art, the electrode tabs of the lithium battery can move due to the vacuumized negative pressure, and the liquid injection hole serving as the vacuumized path is blocked by the electrode tabs, so that the pressure read by the pressure gauge of the sensor is inconsistent with the real pressure inside the battery, and therefore helium cannot be charged into the battery in the next step, the detection process is terminated, and the detection is required to be re-detected, so that the detection precision and efficiency are affected.

The lithium cell that this embodiment provided is carrying out helium and examining (the gas tightness detects) the in-process of evacuation, then can not make and annotate the liquid hole and be blockked up by utmost point ear, and then ensure going on smoothly of evacuation, the pressure that the manometer of inductor read out is unanimous with the inside true pressure of battery, and the detection flow can go on smoothly, does not need repeated detection, the effectual efficiency and the precision that improves the detection.

The lithium cell includes casing, lithium cell top cap and sets up parts such as utmost point ear, plastic piece down in the casing, and above-mentioned lithium cell top cap sets up on the casing, and lithium cell top cap is used for encapsulating utmost point ear, plastic piece etc. and set up parts in the casing down.

It should be noted that the structures of the lithium batteries such as the casing, the tabs, and the lower plastic sheets are similar to those of the related art, and are not described herein again.

Referring to fig. 1 and 2, the lithium battery top cover 010 includes a top cover body 100 and a convex hull 200, the top cover body 100 has a first surface 101 facing the inside of the case and a second surface 102 facing the outside of the case, the top cover body 100 is opened with a liquid injection hole 110, the convex hull 200 is connected with the first surface 101, and the convex hull 200 has a cavity 210 communicated with the liquid injection hole 110. When assembling the lithium battery, the liquid can be injected into the lithium battery through the liquid injection hole 110 and the cavity 210 of the convex hull 200. When helium detection (air tightness detection) is performed on the lithium battery, the vacuum can be pumped and helium gas can be injected through the liquid injection hole 110 and the cavity 210.

It should be noted that the top cover body 100 can be connected to a lower plastic sheet inside the lithium battery, and the convex hull 200 extends toward the lower plastic sheet.

Further, a first mating surface 221 and a second mating surface 222 are arranged on one side of the convex hull 200, which is away from the first surface 101, and the distance between the first mating surface 221 and the first surface 101 is smaller than the distance between the second mating surface 222 and the first surface 101; when the tab of the lithium battery contacts the second mating surface 222, the second mating surface 222 can prevent the tab from contacting the first mating surface 221, so that a gap is formed between the tab and the convex hull 200, and the liquid injection hole 110 is prevented from being blocked by the tab.

When helium detection (air tightness detection) is performed on the lithium battery, vacuum pumping needs to be performed through the liquid injection hole 110, the electrode tabs can move towards the convex hull 200 under the action of negative pressure in the vacuum pumping step, since the distance between the second mating surface 222 and the first surface 101 is greater than the distance between the first mating surface 221 and the first surface 101, when the tab moves into contact with the second mating surface 222, the second mating surface 222 can prevent the tab from contacting the first mating surface 221, so that a gap is formed between the tab and the convex hull 200, and the opening of the cavity 210 far away from the injection hole 110 is prevented from being blocked by the tab, and further the injection hole 110 is prevented from being blocked by the tab, can ensure that the route of evacuation is not blockked up, when carrying out the helium to the lithium cell and examining, can be smooth through annotating liquid hole 110 and cavity 210 evacuation, and then avoid the termination of detection procedure to improve and detect the precision, and improve detection efficiency.

It should be noted that, when the lithium battery top cover 010 is assembled to the lithium battery shell, the top cover can be connected to the lower plastic sheet, specifically, the top cover body 100 is connected to the lower plastic sheet; the tabs may be distributed substantially parallel to the first face 101 of the header body 100.

Optionally, referring to fig. 2, along a direction perpendicular to the first surface 101, the first mating surface 221 and the second mating surface 222 are distributed in a step shape; so set up, when the utmost point ear moves to convex closure 200's direction under the effect of negative pressure, the utmost point ear can contact with second fitting surface 222 earlier, and block by second fitting surface 222 that the utmost point ear moves to contacting with first fitting surface 221, so that form the clearance between utmost point ear and the first fitting surface 221, and even utmost point ear can incline relative to first face 101 under the effect of negative pressure, and contact with first fitting surface 221, the step department between first fitting surface 221 and the second fitting surface 222 also can form the clearance with the utmost point ear, and then ensure that cavity 210 and notes liquid hole 110 are not blocked, can ensure the smooth going on of evacuation when lithium cell gas tightness detects, reduce repeated detection, improve and detect accuracy and efficiency.

Further, with reference to fig. 2, the convex hull 200 includes a first half round table 231 and a second half round table 232 which are connected to each other, one side of the first half round table 231 and one side of the second half round table 232 are both connected to the first surface 101, and the first half round table 231 and the second half round table 232 are spliced to form the cavity 210, specifically, when the first half round table 231 and the second half round table 232 are spliced, an arc concave surface of the first half round table 231 and an arc concave surface of the second half round table 232 are distributed oppositely to form the cavity 210; along the direction perpendicular to the first surface 101, the height of the first half round table 231 is smaller than that of the second half round table 232, the side of the first half round table 231 departing from the first surface 101 is a first mating surface 221, and the side of the second half round table 232 departing from the first surface 101 is a second mating surface 222. So set up, when utmost point ear when the effect of negative pressure is down to convex closure 200's direction removal, utmost point ear can contact with second fitting surface 222 earlier, no matter move to the utmost point ear with convex closure 200 contact whether can contact with first fitting surface 221, all can form the clearance between utmost point ear and the convex closure 200, can be that form the clearance between utmost point ear and the first fitting surface 221, also can be that the junction of first half round platform 231 and second half round platform 232 forms the clearance between the utmost point ear, can annotate liquid hole 110 effectively and not blockked up, and then ensure going on smoothly of helium inspection in-process evacuation, improve detection efficiency.

Still further, both the first mating surface 221 disposed on the first half round table 231 and the second mating surface 222 disposed on the second half round table 232 may be substantially parallel to the first surface 101 and spaced apart from each other. Of course, the first mating surface 221 and the second mating surface 222 may also have an angle with the first surface 101, and the angle may be 1 °, 3 °, 5 °, and the like, and is not limited herein.

It should be noted that, the connection mode between the first half round table 231 and the second half round table 232 and the top cover body 100, and the connection mode between the first half round table 231 and the second half round table 232 can be selected as required, for example: integrally formed, welded, snapped, etc., and is not specifically limited herein.

It should be further noted that, when the first half round table 231 and the second half round table 232 are integrally formed, a portion of the first half round table 231 lower than the second half round table 232 may be formed by die cutting, that is, the first mating surface 221 may be formed by die cutting.

Optionally, referring to fig. 3 and fig. 4, a side of the convex hull 200 away from the first surface 101 has a position-limiting surface 240, an extending surface of the position-limiting surface 240 forms an included angle with the first surface 101, and the first mating surface 221 and the second mating surface 222 are both disposed on the position-limiting surface 240. Specifically, the limiting surface 240 is an inclined surface that is not parallel to the first surface 101, and along a direction perpendicular to the first surface 101, a point of the limiting surface 240 farthest from the first surface 101 is the second mating surface 222, and a point of the limiting surface 240 closest to the first surface 101 is the first mating surface 221; or, the limiting surface 240 is an inclined surface that is not parallel to the first surface 101, and along a direction perpendicular to the first surface 101, a point of the limiting surface 240 that is closest to the first surface 101 is a first mating surface 221, and a point of the limiting surface 240 that is farthest from the first surface 101 and portions of surfaces extending from both sides of the point form a second mating surface 222 together, so that the second mating surface 222 with a larger area is used to block the tab from contacting the first mating surface 221, thereby ensuring that the tab does not block the injection hole 110 under a negative pressure condition.

Optionally, referring to fig. 5, a side of the convex hull 200 away from the first surface 101 has a limiting surface 240, a half of the limiting surface 240 is parallel to the first surface 101 and is a second matching surface 222, and the other half of the limiting surface is disposed at an angle to the first surface 101 and is a first matching surface 221.

Optionally, referring to fig. 6 and 7, the convex hull 200 includes a first boss 251 and a second boss 252, one side of the first boss 251 and one side of the second boss 252 are both connected to the first surface 101, the first boss 251 is provided with a cavity 210, the second boss 252 is connected to the first boss 251, one side of the first boss 251 departing from the first surface 101 is provided with a first mating surface 221, and one side of the second boss 252 departing from the first surface 101 is provided with a second mating surface 222. Specifically, one side surface of the first boss 251, which is away from the first surface 101, is a first mating surface 221 parallel to the first surface 101, and one side surface of the second boss 252, which is away from the first surface 101, is a second mating surface 222 parallel to the first surface 101; thus, the first mating surface 221 and the second mating surface 222 are distributed in a step-like manner, when the tab moves towards the convex hull 200 under the action of negative pressure, the tab can be prevented from contacting the first mating surface 221 by the second mating surface 222, so that a gap for gas to flow is formed between the tab and the convex hull 200, and the liquid injection hole 110 is prevented from being blocked, even if the tab is prevented by the second mating surface 222, the tab can move to contact the first mating surface 221, a gap can be formed between the step formed between the first mating surface 221 and the second mating surface 222 and the tab, and the liquid injection hole 110 is prevented from being blocked.

It should be understood that in some embodiments, a side of the first boss 251 facing away from the first face 101 is not parallel to the first mating face 221 of the first face 101, and a side of the second boss 252 facing away from the first face 101 is not parallel to the second mating face 222 of the first face 101.

The first boss 251 and the second boss 252 may be integrally formed with the top cover body 100, welded, etc., and are not particularly limited herein.

It should be noted that the second boss 252 may be disposed adjacent to the first boss 251 only, and not connected to the first boss 251, for example: the first boss 251 and the second boss 252 are adjacent to each other and spaced apart, or the surface of the second boss 252 is spliced, abutted or attached to the surface of the first boss 251, instead of being fixedly connected, and the like, and is not particularly limited herein.

Alternatively, referring to fig. 7 and 8, the second boss 252 is located within the cavity 210; alternatively, referring to fig. 9 and 10, the second boss 252 is located outside the cavity 210; alternatively, the second bosses 252 may be provided on both the inside and outside of the cavity 210.

Optionally, the cross-section of the cavity 210 is circular in a direction parallel to the first face 101, and the second boss 252 extends in a radial direction of the cavity 210. It should be appreciated that in some embodiments, the second bosses 252 may also extend at an angle to the radial direction of the cavity 210.

Optionally, referring to fig. 9 and 10, the convex hull 200 includes a plurality of the second bosses 252, and the plurality of the second bosses 252 are distributed along the circumferential direction of the first boss 251. Further, the first boss 251 is annular, and a plurality of second bosses 252 are sequentially distributed along the periphery of the first boss 251; or a plurality of second bosses 252 are sequentially distributed along the inner circumference of the first boss 251; or a part of the second bosses 252 are sequentially distributed along the outer circumference of the first boss 251, and the other part of the second bosses 252 are sequentially distributed along the inner circumference of the first boss 251.

When the plurality of second bosses 252 are sequentially distributed along the circumferential direction of the first boss 251, the plurality of second bosses 252 may be uniformly spaced apart, or non-uniformly spaced apart, and are not particularly limited herein.

It should be noted that, in the lithium battery top cover 010 of this embodiment, the electrolyte injection hole 110 is formed in the top cover body 100, the first mating surface 221 and the second mating surface 222 are formed in the convex hull 200 connected to the top cover body 100, and the height difference between the first mating surface 221 and the second mating surface 222 is utilized to prevent the tab from moving to the convex hull 200 to block the electrolyte injection hole 110 under the action of negative pressure, and it is not necessary to increase the distance between the electrolyte injection hole 110 and the tab in order to prevent the tab from blocking the electrolyte injection hole 110 under the action of negative pressure, and further, it is not necessary to increase the thickness of the top cover body 100, so that the design height of the lithium battery is not increased, and the capacity of the.

To sum up, the utility model provides a lithium cell top cap 010 is used for setting up in the casing of lithium cell, and the lithium cell that is provided with this lithium cell top cap 010 can prevent to annotate liquid hole 110 when helium is examined (gas tightness detects), and then ensures going on smoothly of evacuation, avoids the termination of testing procedure to improve and detect the precision, and improve detection efficiency.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A lithium battery top cover is used for being arranged on a shell of a lithium battery and is characterized by comprising a top cover body and a convex hull, wherein the top cover body is provided with a first surface facing the inside of the shell and a second surface facing the outside of the shell, the top cover body is provided with a liquid injection hole, the convex hull is connected with the first surface, and the convex hull is provided with a cavity communicated with the liquid injection hole; wherein the content of the first and second substances,

a first matching surface and a second matching surface are arranged on one side, away from the first surface, of the convex hull, and the distance between the first matching surface and the first surface is smaller than the distance between the second matching surface and the first surface; when the pole lug of the lithium battery is in contact with the second matching surface, the second matching surface can block the pole lug from being in contact with the first matching surface, so that a gap is formed between the pole lug and the convex hull, and the liquid injection hole is prevented from being blocked by the pole lug.

2. The lithium battery top cap of claim 1, wherein the first mating surface and the second mating surface are disposed in a step-like manner along a direction perpendicular to the first surface.

3. The lithium battery top cap of claim 2, wherein the convex hull comprises a first half round platform and a second half round platform that are connected to each other, wherein one side of the first half round platform and one side of the second half round platform are both connected to the first face, and the first half round platform and the second half round platform are spliced to form the cavity; along the perpendicular to the direction of first face, the height of first half round platform is less than the height of second half round platform, just first half round platform deviates from one side of first face is first fitting surface, the second half round platform is kept away from one side of first face is the second fitting surface.

4. The lithium battery top cap of claim 1, wherein one side of the convex hull facing away from the first surface is provided with a limiting surface, an extending surface of the limiting surface is arranged at an included angle with the first surface, and the first matching surface and the second matching surface are both arranged on the limiting surface.

5. The lithium battery top cap of claim 1, characterized in that the convex hull comprises a first boss and a second boss, one side of the first boss and one side of the second boss are both connected with the first face, the first boss is provided with the cavity, one side of the first boss departing from the first face is provided with the first mating face, and one side of the second boss departing from the first face is provided with the second mating face.

6. The lithium battery top cap of claim 5, wherein the second boss is located within the cavity.

7. The lithium battery top cap of claim 5, wherein the boss is located outside the cavity.

8. The lithium battery top cap of claim 5, wherein the cavity has a circular cross-section in a direction parallel to the first face, and the second boss extends in a radial direction of the cavity.

9. The lithium battery top cap of claim 5, wherein the convex hull comprises a plurality of the second bosses, and the plurality of the second bosses are distributed along a circumferential direction of the first bosses.

10. A lithium battery comprising a lithium battery top cover as claimed in any one of claims 1 to 9.

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