CN111916588A

CN111916588A - Cap and battery with same

Info

Publication number: CN111916588A
Application number: CN202010901366.1A
Authority: CN
Inventors: 李吉栋; 徐悦斌; 何巍; 李碧梅; 张梦菲; 祝媛; ***; 刘金成
Original assignee: Huizhou Yiwei Energy Battery Co ltd; Eve Energy Co Ltd
Current assignee: Eve Energy Co Ltd
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2020-11-10

Abstract

The invention discloses a cap and a battery with the cap. And at least one side of the battery cap body is provided with an anti-corrosion layer. According to the battery cap, the anti-corrosion layer is arranged on at least one side of the cap body, so that the problem that the cap is blackened due to corrosion of the cap can be solved, and the safety risk of the battery is reduced.

Description

Cap and battery with same

Technical Field

The invention belongs to the technical field of new energy, and relates to a cap and a battery with the cap.

Background

The cap of the positive terminal of the battery in the market is generally made of stainless steel, such as 304, 316L; the anode tab inside the battery cell is generally made of Al and is electrically connected through ultrasonic welding, resistance welding and other modes. But the structural product generally has the problem of corrosion and blackening of the inner part of the cap. In the use or storage process, the corrosion of the cap is intensified along with the action of temperature and time, and oxides generated by the corrosion of the cap fall into the battery cell and cause internal short circuit, so that the battery is invalid or has safety risk.

Disclosure of Invention

Aiming at the problem that the existing cap is corroded and blackened, the invention provides the cap, the preparation method thereof and the battery with the cap, and the problem that the cap is corroded and blackened and the safety risk of the battery can be solved.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a battery cap comprising a cap body having an anti-corrosion layer disposed on at least one side of the cap body.

According to the invention, the anti-corrosion layer is arranged on at least one side of the cap body, so that the problem of blackening of the cap can be solved, and the safety risk of the battery is reduced.

The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.

Preferably, the base material of the cap body is stainless steel, preferably 304 steel, 304L steel, 316 steel or 316L steel. But is not limited to the above listed species and other species commonly used in the art for making caps are also suitable for use in the present invention.

Preferably, the corrosion protection layer is selected from an aluminum film or a nickel film.

Since the aluminum film is easily oxidized by air to form a dense oxide film, the detection of the cap product of the present invention may have an alumina component.

It should also be noted that the nickel film is easily oxidized into an oxide film in a certain environment (for example, in air or in relatively humid air), so that the cap product of the present invention may be detected to have a nickel oxide component.

As a preferable technical scheme of the cap, an M layer is arranged between the cap body and the anti-corrosion layer, and M is a metal element.

And/or a transition layer is arranged between the cap body and the anti-corrosion layer, and the transition layer is an M/Al transition layer or an M/Ni transition layer.

The common material of the cap is stainless steel, the problem of untight binding force of a coating between the anti-corrosion layer and the stainless steel exists when the anti-corrosion layer is directly arranged on the cap substrate, the anti-corrosion layer and the cap substrate are easy to separate, and the risk of failure of the coating exists. Aiming at the problem, the pre-plating layer (namely the M layer and/or the transition layer, wherein the transition layer is an M/Al transition layer or an M/Ni transition layer) capable of improving the bonding force is added between the two layers, so that the bonding force between the two layers can be enhanced, and the risk of coating failure is avoided.

Preferably, M is a transition metal element, and more preferably at least one of Cr and Ti. But not limited to the above listed kinds, other chemical elements that can increase the binding force between the corrosion prevention layer and the cap substrate can be used in the present invention.

In another preferred embodiment of the cap of the present invention, an aluminum film is disposed on at least one side of the cap body, and an M/Al transition layer and an M layer are sequentially disposed between the cap body and the aluminum film along a direction away from the aluminum film toward the cap body. Taking M as Cr element as an example, a Cr layer can be prepared at the position of the cap substrate, then a chromium-aluminum transition layer (also called Cr/Al transition layer) is prepared, and finally a pure Al layer (also called aluminum film) is prepared.

As another preferable technical solution of the cap of the present invention, at least one side of the cap body is provided with a nickel film, and an M/Ni transition layer and an M layer are sequentially disposed between the cap body and the nickel film along a direction away from the nickel film and toward the cap body. Taking M as Ti element as an example, a Ti layer can be prepared at the position of the cap substrate, a Ti-Ni transition layer (namely Ti/Ni transition layer) is prepared, and a pure Ni layer (namely nickel film) is prepared.

The M/Al transition layer and/or the M/Ni transition layer are preferably introduced in the form of a co-plating layer (the preparation method of the co-plating layer is not limited, and can be electroplating, chemical plating, magnetron sputtering and the like, for example), and the two elements are mutually dispersed to form the M/Al transition layer or the M/Ni transition layer, so that the effect of increasing the bonding force between the aluminum film and the substrate or between the nickel film and the substrate can be better achieved.

Preferably, the thickness of the corrosion protection layer is 100 μm or less, such as 100 μm, 90 μm, 80 μm, 70 μm, 65 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 8 μm, 5 μm, 3 μm, 2 μm or 1 μm, etc., preferably 1 μm to 20 μm.

Preferably, the thickness of the M layer is 50 μ M or less, for example 50 μ M, 40 μ M, 35 μ M, 30 μ M, 20 μ M, 10 μ M, 9 μ M, 7.5 μ M, 5 μ M, 3 μ M, 2 μ M, 1 μ M, 0.5 μ M, 0.1 μ M, 0.05 μ M or 0.001 etc., preferably 0.001 μ M to 20 μ M.

Preferably, the thickness of the M/Al transition layer and the M/Ni transition layer are independently ≦ 50 μ M, such as 50 μ M, 40 μ M, 30 μ M, 25 μ M, 20 μ M, 10 μ M, 8 μ M, 6.5 μ M, 4 μ M, 3 μ M, 2 μ M, 1 μ M, 0.5 μ M, 0.1 μ M, 0.05 μ M, or 0.001, and preferably 0.001 μ M to 20 μ M.

In another preferred embodiment of the cap of the present invention, the corrosion-resistant layer is prepared by a vacuum magnetron sputtering method.

The anti-corrosion layer is arranged on the inner side of the cap by adopting a vacuum magnetron sputtering method, so that the anti-corrosion layer with a compact structure can be obtained, and the problem that the cap is corroded and blackened is solved.

The method of vacuum magnetron sputtering for preparing the anti-corrosion layer belongs to a physical method. By taking the preparation of the aluminum film by vacuum magnetron sputtering as an example, under the impact of high-energy ions, aluminum is coated in an atomic deposition mode to form a compact aluminum coating, namely the aluminum film. The above explanation of the mechanism is only illustrative and not limitative of the present invention, and similarly, the same applies to other kinds of corrosion protection layers.

Compared with the chemical method for preparing the anti-corrosion layer, the vacuum magnetron sputtering method has the following advantages: according to the method, the cap can be subjected to vacuum magnetron sputtering coating after being subjected to punch forming, the anti-corrosion layer can be prevented from being formed on the outer side of the cap body in a mask covering mode, and the prepared anti-corrosion layer is more compact and has a good anti-corrosion effect.

By taking the anti-corrosion layer as the aluminum film as an example to compare the advantages and the disadvantages of the anti-corrosion layer and the aluminum film, a more compact aluminum film can be obtained by a vacuum magnetron sputtering method, and the anti-corrosion effect is good; the chemical method is not suitable for preparing the aluminum coating film because the aluminum has high activity, is easy to generate chemical reaction and is not suitable for the chemical method (such as water plating); moreover, the chemical method for preparing the aluminum film requires aluminum plating and then stamping, which may cause the aluminum film to be damaged in the stamping process, and chemical plating is generally carried out in a liquid phase, which makes it difficult to avoid the aluminum film not forming on the outer side of the cap body.

Preferably, the aluminum film or the nickel film is prepared by a vacuum magnetron sputtering method.

Preferably, in the process of preparing the aluminum film, the vacuum magnetron sputtering adopts an aluminum target material, and the purity of the aluminum target material is preferably more than 90%, and more preferably more than 99.99%.

Preferably, an M layer is prepared between the cap body and the aluminum film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an M target material, and the purity of the M target material is preferably more than 90%, and more preferably more than 99.99%.

Preferably, an M/Al transition layer is prepared between the aluminum film and the M layer or between the cap body and the aluminum film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an aluminum target and an M target, and the purity of the aluminum target and the purity of the M target are preferably 90% or more independently, and further preferably 99.99% or more independently.

Preferably, the vacuum degree of the vacuum magnetron sputtering during the preparation of the aluminum film, the M/Al transition layer and the M layer is independently 0.2Pa-0.5Pa, such as 0.2Pa, 0.25Pa, 0.3Pa, 0.35Pa, 0.4Pa or 0.5Pa, etc.

Preferably, the bias voltage of the vacuum magnetron sputtering during the preparation of the aluminum film, the M/Al transition layer and the M layer is independently 80V-130V, such as 80V, 90V, 95V, 100V, 105V, 110V, 120V or 130V, etc.

Preferably, in the process of preparing the nickel film, the vacuum magnetron sputtering adopts a nickel target material, and the purity of the nickel target material is preferably more than 90%, and more preferably more than 99.99%.

Preferably, an M layer is prepared between the cap body and the nickel film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an M target material, and the purity of the M target material is preferably more than 90%, and more preferably more than 99.99%.

Preferably, an M/Ni transition layer is prepared between the nickel film and the M layer or the M/Ni transition layer is prepared between the cap body and the aluminum film by adopting a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts a nickel target and an M target, and the purity of the nickel target and the purity of the M target are preferably 90% or more independently, and further preferably 99.99% or more independently.

Preferably, the vacuum degree of the vacuum magnetron sputtering during the preparation of the nickel film, the M/Ni transition layer and the M layer is independently 0.2Pa to 0.5Pa, such as 0.2Pa, 0.25Pa, 0.3Pa, 0.35Pa, 0.4Pa or 0.5 Pa.

Preferably, the bias voltage of the vacuum magnetron sputtering during the preparation of the nickel film, the M/Ni transition layer and the M layer is independently 80V-130V, such as 80V, 90V, 95V, 100V, 105V, 110V, 120V or 130V, etc.

Preferably, the thickness of the anti-corrosion layer prepared by the vacuum magnetron sputtering method is less than or equal to 100 μm, and preferably 1 μm to 20 μm.

Preferably, the thicknesses of the M layer, the M/Al transition layer and the M/Ni transition layer prepared by the vacuum magnetron sputtering method are independently less than or equal to 100 μ M, preferably less than or equal to 50 μ M, and preferably 0.001 μ M to 20 μ M.

When the thickness of the coating prepared by the vacuum magnetron sputtering method is too large, the aluminum film formed by magnetron sputtering may have uneven density in the thickness direction, the structural stability is deteriorated, and the time and material cost are increased.

In a second aspect, the invention provides a battery, which includes a battery core, a bottom shell, and the cap of the first aspect, wherein a receiving cavity for receiving the battery core is formed between the bottom shell and the cap, the bottom shell and the cap are insulated and sealed by a sealing member, and an anti-corrosion layer is disposed on one side of the cap, which is located in the receiving cavity.

The form of the battery of the present invention is not particularly limited, and may be a bean type battery, for example. The improved scheme of the invention has better effect on solving the problem of corrosion and blackening of the bean type battery cap.

Preferably, the block includes the roof and encloses and establish first leg in roof one side, the drain pan includes the bottom plate and encloses and establish second leg in bottom plate one side, first leg cover is located outside the second leg, or second leg cover is located outside the first leg.

It should be noted that, when the first surrounding wall of the cap is sleeved outside the second surrounding wall of the bottom case, the anti-corrosion layer may be disposed only on the top region of the cap.

Preferably, the top plate and the first surrounding wall of the cap are both provided with a corrosion protection layer.

Preferably, the battery core comprises a pole piece and a diaphragm, the pole piece comprises a positive pole piece and a negative pole piece, and the diaphragm is located between the positive pole piece and the negative pole piece.

Preferably, the pole piece comprises a current collector and an active material coated on the current collector.

Preferably, the positive pole piece is provided with a positive pole lug, and the positive pole lug is connected with the cap.

Preferably, the material of the positive tab is selected from aluminum or nickel.

Preferably, the battery cell further comprises a negative electrode tab.

The arrangement position of the negative electrode tab is not limited, and the negative electrode tab and the positive electrode tab can be arranged on the same side or different sides. Preferably, the positive tab is connected with the cap, and the negative tab is connected with the bottom shell.

Preferably, the battery cell is a winding battery cell, the diaphragm has an isolation portion extending to two ends of the negative plate along an axis direction of the winding battery cell, and the isolation portion is used for electrically insulating a tab of the winding battery cell and an end surface of the winding battery cell.

Preferably, the battery cell is a laminated battery cell, and the diaphragm has an isolation portion extending to an edge of a negative plate of the laminated battery cell, and the isolation portion is used for electrically insulating a tab of the laminated battery cell from a terminal surface of the laminated battery cell.

The setting of isolation part can prevent effectively that utmost point ear and electric core tip from taking place the electrical contact, need not additionally to set up insulating gasket, has reduced the preparation degree of difficulty and the cost of battery, has promoted production efficiency, need not to change the preparation technology and the equipment of current battery simultaneously, is favorable to the large-scale production of battery, and insulating nature is good.

Preferably, the diameter to height ratio of the battery is ≧ 1, preferably > 1.

Preferably, the current collector contains a hollow foil area which is not coated with active substances, the hollow foil area forms an extension part, and the extension part forms a tab which is a positive tab and/or a negative tab.

Preferably, the extension part is folded after being bent, and the extension part and the pole piece form an included angle.

The angle size that the extension was bent is according to the nimble adjustment of the requirement of electric core when the encapsulation, specifically, the extension uses the position of being connected with the end of pole piece as the fulcrum and buckles, buckles first contained angle alpha, and wherein first contained angle alpha is 90, and this angle can make the extension be convenient for draw forth from the tip of electric core, shortens the length of utmost point ear, has reduced manufacturing cost. Of course, the bending angle of the extending portion is not limited to 90 °, and the first included angle α may also be set to 30 °, 45 °, 100 °, or 120 °, etc., as required.

Preferably, the battery core further comprises a reinforcing member wrapping the overlapped position of the extension part. Set up extra reinforcement through the coincide position at the extension, the reinforcement can strengthen the intensity of the coincide position of bending, is prevented effectively that the extension from being broken after bending, protects the integrality of utmost point ear, has also strengthened the bulk strength of utmost point ear simultaneously.

In a preferred embodiment, the reinforcement is an adhesive tape wrapped around the outside of the overlapping position of the extensions. The reinforcing piece is set as an adhesive tape, so that on one hand, the overlapped position of the bent extension part can be buffered, the stress of the bent extension part can be relieved to a certain extent, and the phenomenon that the tab is separated from the pole piece due to the breakage of the extension part at the overlapped position is effectively reduced; on the other hand, the adhesive tape is utilized to protect and shape the structure of the overlapping position of the extension part, so that the normal use of the winding type battery cell is prevented from being influenced by the deformation of the overlapping position of the bent extension part after the tab is used for a long time. To further enhance the protective effect of the tape on the extension, multiple layers of tape may be wrapped in the laminating position.

In another preferred technical solution, the reinforcing member is a double-sided adhesive tape, a first laminating surface and a second laminating surface which are attached to each other are disposed on the extending portion and located at the laminating position, and the double-sided adhesive tape is disposed between the first laminating surface and the second laminating surface. The setting of double faced adhesive tape can prevent effectively that first coincide face and second coincide face from separating to avoid utmost point ear to occupy the space between drain pan and the block.

Preferably, the extension part is bent for multiple times at the same position, so that the thickness of the overlapping position is increased, and the strength of the pole piece is further improved.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, the anti-corrosion layer is arranged on at least one side of the cap body, so that the problem that the cap is blackened due to corrosion of the cap can be solved, and the safety risk of the battery is reduced.

According to the preferred technical scheme, the anti-corrosion layer is arranged on the inner side of the cap by adopting a vacuum magnetron sputtering method, and the anti-corrosion layer with a compact structure can be obtained, so that the corrosion and blackening of the cap and the safety risk of a battery are better eliminated.

According to the preferred technical scheme, the pre-plating layer (namely the M layer and/or the transition layer) capable of improving the binding force is added between the anti-corrosion layer and the cap substrate, so that the aluminum plating effect is better, the binding force between the anti-corrosion layer and the cap substrate is strong, and the risk of failure of the anti-corrosion layer is avoided.

Drawings

Fig. 1 is a schematic cross-sectional view of a battery cap according to an embodiment of the present invention.

Fig. 2 is a schematic structural view of a battery according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a battery cell according to an embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view of a bottom case according to an embodiment of the invention.

Fig. 5 is a schematic structural diagram of a pole piece and a tab according to an embodiment of the invention.

Fig. 6 is a schematic structural diagram of a pole piece and a tab according to another embodiment of the present invention.

Fig. 7(a) and 7(b) are cell HTHH test results of example 3.

Fig. 8(a) and 8(b) are results of the cell HTHH test of comparative example 1.

Fig. 9 is a storage test of capped cells of example 3 and comparative example 1 at 60 ℃ & 90% RH.

Fig. 10 is a photograph of an actual cap of example 3 disassembled after 28 days of cycling + HTHH test of the capped cells.

Fig. 11 is the results of the cap EDS disassembled after 28 days of cycling + HTHH testing of the cap cells of example 3.

Fig. 12 is a photograph of the cap in substance before the cap is assembled into a cap cell in example 3.

Fig. 13 is the results of the capping EDS before the capping is assembled into a capped cell of example 3.

Fig. 14 is an ultrasonic welding section analysis view of the cap and the tab of the embodiment 3.

Fig. 15 is an ultrasonic welding section analysis view of the cap and the tab of example 2.

Fig. 16 is a graph showing the results of the cap of example 3 in testing the plating adhesion by the one-hundred-grid method.

Fig. 17 is a charge curve of a battery assembled from the caps of example 3 and comparative example 1.

1-a cover cap, 11-a top plate, 12-a first surrounding wall, 121-a first outer wall plate, 122-a second outer wall plate, 123-a third outer wall plate, 21-an anti-corrosion layer, 22-a transition layer, 23-M layers, 3-a sealing element, 4-an ultrasonic welding spot, 5-an electric core, 51-a tab, 511-a positive tab, 512-a negative tab, 52-an extension part, 521 and a superposition position; 53. a reinforcement; 54-pole piece, 541-positive pole piece, 542-negative pole piece, 55-diaphragm, 551-separator, 6-bottom shell, 61-bottom plate, 62-second surrounding wall, 621-first inner wall plate, 622-second inner wall plate, 623-third inner wall plate, 624-fourth inner wall plate, 625-fifth inner wall plate; 23. 22 and 21 are in turn disposed inwardly of 1.

Detailed Description

In order to make the technical problems solved, technical solutions adopted and technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The embodiment of the invention provides a cap, which comprises a cap body, wherein at least one side of the cap body is provided with an anti-corrosion layer.

In one embodiment, the base material of the cap body is stainless steel, preferably 304 steel, 304L steel, 316 steel or 316L steel. But is not limited to the above listed species and other species commonly used in the art for making caps are also suitable for use in the present invention.

In one embodiment, the corrosion protection layer is selected from an aluminum film or a nickel film.

In one embodiment, an M layer is disposed between the cap body and the anti-corrosion layer, where M is a metal element; and/or a transition layer is arranged between the cap body and the anti-corrosion layer, and the transition layer is an M/Al transition layer or an M/Ni transition layer.

Further, M is a transition metal element, and more preferably at least one of Cr and Ti. But not limited to the above listed kinds, other chemical elements that can increase the binding force between the corrosion prevention layer and the cap substrate can be used in the present invention.

In one embodiment, an aluminum film is disposed on at least one side of the cap body, and an M/Al transition layer and an M layer are sequentially disposed between the cap body and the aluminum film along a direction away from the aluminum film and toward the cap body. Because the binding force between the M layer and the cap substrate and between the M/Al transition layer is strong, the binding force between the M/Al transition layer and the aluminum film is also strong, and the problem that the aluminum film is easy to fall off to cause failure of the aluminum film can be better solved.

In one embodiment, a nickel film is disposed on at least one side of the cap body, and an M/Ni transition layer and an M layer are sequentially disposed between the cap body and the nickel film along a direction away from the nickel film and toward the cap body. Because the binding force between the M layer and the cap substrate and between the M/Ni transition layer and the nickel film is strong, the problem that the nickel film fails due to the fact that the aluminum film is easy to fall off can be better solved.

In an embodiment, the M/Al transition layer and/or the M/Ni transition layer are preferably introduced in the form of a co-plating layer (the preparation method of the co-plating layer is not limited, and may be, for example, electroplating, electroless plating, magnetron sputtering, etc.), and the two elements are mutually dispersed to form the M/Al transition layer or the M/Ni transition layer, so that the effect of increasing the bonding force between the aluminum film and the substrate or between the nickel film and the substrate can be better achieved.

Furthermore, the thickness of the anti-corrosion layer is less than or equal to 100 μm, and preferably ranges from 1 μm to 20 μm.

Further, the thickness of the M layer is 50 μ M or less, preferably 0.001 μ M to 20 μ M.

Further, the thickness of the M/Al transition layer and the M/Ni transition layer is independently 50 μ M or less, preferably 0.001 μ M to 20 μ M.

In one embodiment, the anti-corrosion layer is prepared by a vacuum magnetron sputtering method, and the anti-corrosion layer is arranged on the inner side of the cap by the vacuum magnetron sputtering method, so that the anti-corrosion layer with a compact structure can be obtained, and the problem of corrosion and blackening of the cap is solved.

In one embodiment, the aluminum film or the nickel film is prepared by a vacuum magnetron sputtering method.

In one embodiment, in the process of preparing the aluminum film, the vacuum magnetron sputtering adopts an aluminum target material. Further, the purity of the aluminum target is 90% or more, and more preferably 99.99% or more.

In one embodiment, an M layer is prepared between the cap body and the aluminum film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an M target material. Further, the purity of the M target is 90% or more, and more preferably 99.99% or more.

In one embodiment, an M/Al transition layer is prepared between an aluminum film and an M layer or between a cap body and the aluminum film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an aluminum target and an M target. Further, the purity of the aluminum target and the purity of the M target are independently 90% or more, and more preferably 99.99% or more.

Further, in the process of preparing the aluminum film, the M/Al transition layer and the M layer, the vacuum degree of the vacuum magnetron sputtering is independently 0.2Pa-0.5 Pa.

Further, in the process of preparing the aluminum film, the M/Al transition layer and the M layer, the bias voltage of the vacuum magnetron sputtering is independently 80V-130V.

In one embodiment, in the process of preparing the nickel film, the vacuum magnetron sputtering employs a nickel target. Further, the purity of the nickel target is 90% or more, and more preferably 99.99% or more.

In one embodiment, an M layer is prepared between the cap body and the nickel film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an M target material. Further, the purity of the M target is 90% or more, and more preferably 99.99% or more.

In one embodiment, an M/Ni transition layer is prepared between a nickel film and an M layer or between a cap body and an aluminum film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts a nickel target and an M target. Further, the purity of the nickel target and the purity of the M target are independently 90% or more, and more preferably 99.99% or more.

Further, in the process of preparing the nickel film, the M/Ni transition layer and the M layer, the vacuum degree of the vacuum magnetron sputtering is independently 0.2Pa-0.5 Pa.

Further, in the process of preparing the nickel film, the M/Ni transition layer and the M layer, the bias voltage of the vacuum magnetron sputtering is independently 80V-130V.

Furthermore, the thickness of the anti-corrosion layer prepared by the vacuum magnetron sputtering method is less than or equal to 100 μm, and preferably 1 μm to 20 μm.

Further, the thicknesses of the M layer, the M/Al transition layer and the M/Ni transition layer prepared by the vacuum magnetron sputtering method are independently less than or equal to 100 μ M, preferably less than or equal to 50 μ M, and preferably 0.001-20 μ M.

When the thickness of the coating prepared by the vacuum magnetron sputtering method is too large, the aluminum film formed by magnetron sputtering may have uneven density in the thickness direction, the structural stability is deteriorated, and the time cost is increased.

The embodiment of the invention also provides a battery, as shown in fig. 2, the battery comprises a battery core 5, a bottom shell 6 and the cap 1, a containing cavity for containing the battery core is formed between the bottom shell 6 and the cap 1, the bottom shell 6 and the cap 1 are insulated and sealed by a sealing member 3, and an anti-corrosion layer is arranged on one side of the cap 1, which is located in the containing cavity. Specifically, as shown in fig. 4, the bottom case 6 includes a bottom plate 61 and a second surrounding wall 62 surrounding the bottom plate 61. The second surrounding wall 62 comprises a first inner wall plate 621, a second inner wall plate 622, a third inner wall plate 623, a fourth inner wall plate 624 and a fifth inner wall plate 625 which are sequentially connected along the axial direction thereof, the fifth inner wall plate 625 is vertically connected with the bottom plate 61, the fourth inner wall plate 624 inclines towards one side of the center of the second surrounding wall 62, the third inner wall plate 623 and the first inner wall plate 621 are both vertical to the bottom plate 61, the second inner wall plate 622 inclines towards one side far away from the center of the second surrounding wall 62,

specifically, as shown in fig. 1, the cap 1 includes a top plate 11 and a first surrounding wall 12 surrounding one side of the top plate 11, the first surrounding wall 12 includes a first outer wall plate 121, a second outer wall plate 122 and a third outer wall plate 123 sequentially connected along an axial direction thereof, the first outer wall plate 121 is perpendicularly connected to the top plate 11, the second outer wall plate 122 is inclined toward a side away from a center of the first surrounding wall 12, and the third outer wall plate 123 is inclined toward a side away from the center of the first surrounding wall 12.

Specifically, the first surrounding wall 12 is sleeved outside the second surrounding wall 62, a sealing element 3 is sandwiched between the first surrounding wall 12 and the second surrounding wall 62, the first outer wall panel 121 and the first inner wall panel 621 are parallel to each other and abut against each other through the sealing element 3, the second outer wall panel 122 and the second inner wall panel 622 are parallel to each other and abut against each other through the sealing element 3, and the sealing element 3 on one side of the third inner wall panel 623 and the fourth inner wall panel 624 is clamped tightly by the third outer wall panel 123.

Of course, the third outer wall panel 123 is not limited to being inclined to the side of the center of the first wall 12 as a whole, and the third outer wall panel 123 may be provided in other configurations, for example, the third outer wall panel 123 includes a first sub-wall panel and a second sub-wall panel arranged at an included angle, the first sub-wall panel is connected with the second outer wall panel and is perpendicular to the top panel 11, and the second sub-wall panel is inclined to the side of the center of the first wall 12.

Specifically, the first sub-wall plate and the third inner wall plate 623 are parallel and abut against each other through the sealing member 3, and the second sub-wall plate and the fourth inner wall plate 624 are parallel and abut against each other through the sealing member 3, and at this time, preferably, the second outer wall plate 122 and the second sub-wall plate are symmetrically arranged along the first sub-wall plate.

The material of the bottom shell 6 is not limited in the present invention, and may be a steel shell, for example.

Specifically, the battery cell 5 is a winding battery cell (see fig. 3 for a schematic structural diagram thereof), a pole piece 54 of the winding battery cell 5 includes a current collector and an active material coated on the current collector, the pole piece 54 includes a negative pole piece 541 and a positive pole piece 542, a separator 55 is disposed between the negative pole piece 541 and the positive pole piece 542, the current collector includes an empty foil area not coated with the active material, the empty foil area forms an extension portion 52, the extension portion 52 forms a tab 51, preferably, the extension portion 52 is partially overlapped after being bent, and the extension portion 52 and the pole piece 54 are disposed at an included angle. The tab 51 is directly formed after the extension part 52 of the current collector of the pole piece 54 is bent, the process of welding the tab 51 is omitted, the production efficiency is improved, the internal resistance of the winding type battery cell 5 is reduced, and meanwhile, the integrally formed tab 51 and the pole piece 54 have higher strength and are not easy to separate.

Of course, in other embodiments, an externally welded tab may also be used, namely: and welding a metal conductor as a tab on the empty foil area of the current collector which is not coated with the active substance.

The size of the angle of bending of the extension portion can be flexibly adjusted according to the requirement of the battery cell during packaging, specifically, as shown in fig. 5 and 6, the extension portion is bent by taking the position connected with the end portion of the pole piece as a pivot, and is bent by a first included angle alpha, wherein the first included angle alpha is 90 degrees, so that the extension portion can be conveniently led out from the end portion of the battery cell, the length of the tab is shortened, and the manufacturing cost is reduced. Of course, the bending angle of the extending portion is not limited to 90 °, and the first included angle α may also be set to 30 °, 45 °, 100 °, or 120 °, etc., as required.

In one embodiment, as shown in fig. 5 and 6, the overlapping position 521 of the extension 52 is provided with a reinforcement 53. By arranging the additional reinforcing piece 53 at the overlapping position 521 of the extension part 52, the reinforcing piece 53 can reinforce the strength of the overlapping position 521 during bending, the extension part 52 is effectively prevented from being broken after being bent, the integrity of the tab 51 is protected, and the overall strength of the tab 51 is also reinforced.

In one embodiment, the reinforcement is an adhesive tape wrapped around the outside of the overlapping position of the extensions. The reinforcing piece is set as an adhesive tape, so that on one hand, the overlapped position of the bent extension part can be buffered, the stress of the bent extension part can be relieved to a certain extent, and the phenomenon that the tab is separated from the pole piece due to the breakage of the extension part at the overlapped position is effectively reduced; on the other hand, the adhesive tape is utilized to protect and shape the structure of the overlapping position of the extension part, so that the normal use of the winding type battery cell is prevented from being influenced by the deformation of the overlapping position of the bent extension part after the tab is used for a long time. To further enhance the protective effect of the tape on the extension, multiple layers of tape may be wrapped in the laminating position.

In another embodiment, the reinforcement member is a double-sided adhesive tape, the extension portion is provided with a first laminating surface and a second laminating surface which are attached to each other and located at the laminating position, and the double-sided adhesive tape is disposed between the first laminating surface and the second laminating surface. The setting of double faced adhesive tape can prevent effectively that first coincide face and second coincide face from separating to avoid utmost point ear to occupy the space between drain pan and the block.

In one embodiment, as shown in fig. 3, the separator 55 has a separation portion 551 extending to two ends of the negative electrode plate along the axial direction of the wound battery cell, and the separation portion 551 is used to electrically insulate the tab 51 of the wound battery cell 5 from the end surface of the wound battery cell 5.

The tab 51 of the winding-type battery cell 5 is divided into a positive tab 511 and a negative tab 512, the positive tab 511 is connected with the cap 1, and the negative tab 512 is connected with the bottom case 6. The winding type battery cell 5 can be in a cylindrical shape, a square column shape, an elliptic column shape and the like.

In one embodiment, the region of the negative electrode current collector not coated with the active material is formed with an extension part as a negative electrode tab, but a tab may be additionally welded in the region of the negative electrode current collector.

In one embodiment, as shown in fig. 2, the positive tab 511 is connected to the cap 1 by ultrasonic welding, and fig. 4 shows ultrasonic welding points, but the tab may be connected to the housing by other welding methods.

In one embodiment, the material of the positive tab 511 is selected from aluminum or nickel.

Specifically, when the corrosion-proof layer 23 is provided on the inside surface of the space formed by the top plate 11 and the first wall 12, it is satisfied that: the anti-corrosion layer 23 shields all areas of the cap 1 within the receiving cavity (e.g., the top area). More preferably, both the top plate 11 and the first peripheral wall 12 of the cap are provided with a corrosion protection layer.

Example 1

In a specific embodiment, the invention provides a cap 1 as shown in fig. 1, the cap 1 includes a cap body, the cap body includes a top plate 11 and a first surrounding wall 12 annularly disposed on one side of the top plate 11, an M layer 23, a transition layer 22 and an anti-corrosion layer 21 are sequentially disposed inside a space formed by the top plate 11 and the first surrounding wall 12 or inside the top plate 11, a substrate of the cap body is 316L steel, the M layer 23 is a chromium layer, the transition layer 22 is a Cr/Al transition layer (specifically, a chromium-aluminum co-plating layer), and the anti-corrosion layer 21 is an aluminum film.

The thickness of the chromium layer is less than or equal to 50 μm, preferably 0.001 μm to 20 μm.

The thickness of the Cr/Al transition layer is less than or equal to 50 μm, and preferably 0.001-20 μm.

The thickness of the aluminum film is less than or equal to 100 μm, preferably 1 μm to 20 μm.

The present embodiment further provides a battery, as shown in fig. 2, including a battery cell 5, a bottom case 6 and the above-mentioned cap 1, a containing cavity for containing the battery cell is formed between the bottom case 6 and the cap 1, the bottom case 6 and the cap 1 are insulated and sealed by a sealing member 3, and an anti-corrosion layer of the cap 1 faces one side of the containing cavity. The specific embodiment also provides a preparation method of the battery, which comprises the following steps:

providing a metal piece, stamping to form a cap body of the bottom shell 6 and the cap 1, and sequentially forming a chromium layer, a chromium-aluminum co-plating layer and an aluminum film on the cap body by adopting a vacuum magnetron sputtering method, wherein the specific plating layer preparation process comprises the following steps:

(1) performing vacuum magnetron sputtering by adopting a chromium target (with the purity of 99.99 percent), wherein the vacuum degree is 0.4Pa, and the bias voltage is 110V to form a chromium layer;

(2) performing vacuum magnetron sputtering on a chromium target (with the purity of 99.99%) and an aluminum target (with the purity of 99.995%) under the conditions that the vacuum degree is 0.4Pa and the bias voltage is 100V to form a chromium-aluminum co-plating layer;

(3) performing vacuum magnetron sputtering by adopting an aluminum target (with the purity of 99.995 percent) with the vacuum degree of 0.3Pa and the bias voltage of 100V to form an aluminum film, thus obtaining a cap 1;

winding the negative electrode sheet 541, the diaphragm 55 and the positive electrode sheet 542 to obtain the battery cell 5, and setting the positive electrode tab 511 and the negative electrode tab 512, wherein the positive electrode tab 511 is made of aluminum, and the positive electrode tab 511 is set in the following manner: the current collector of the negative electrode sheet 541 contains a blank foil area which is not coated with active material, the blank foil area forms an extension portion 52, the extension portion 52 forms a positive electrode tab 511, the extension portion 52 is folded and partially overlapped, and the extension portion 52 and the electrode sheet 54 are arranged at an included angle (for example, 90 °).

Sleeving the sealing element 3 on the cap 1 or the bottom shell 6 in advance, placing the battery cell 5 in the bottom shell 6, connecting the free end of the positive lug 511 with one side of the cap 1 containing the anti-corrosion layer 23 through ultrasonic welding, connecting the negative lug 512 with the bottom plate 61 of the bottom shell 6, injecting liquid, and assembling the bottom shell 6 and the cap 1 to obtain the battery (the diameter of the battery is more than or equal to 1 in height).

Example 2

The difference from embodiment 1 is that an aluminum film is directly provided inside the space formed by the top plate 11 and the first wall 12 or inside the top plate 11 without a chromium layer and a Cr/Al transition layer.

Example 3

The difference from embodiment 1 is that a chromium layer and an aluminum film are provided in this order inside the space formed by the top plate 11 and the first wall 12 or inside the top plate 11, without containing a Cr/Al transition layer.

Example 4

The difference from embodiment 1 is that a Cr/Al transition layer and an aluminum film are provided in this order inside the space formed by the top plate 11 and the first wall 12 or inside the top plate 11, without containing a chromium layer.

Example 5

This example differs from example 1 in that the chromium layer was replaced by a titanium layer and the Cr/Al transition layer was replaced by a Ti/Al transition layer.

Example 6

This example differs from example 3 in that the chromium layer was replaced by a titanium layer

Example 7

The difference from the embodiment 1 is that the specific coating preparation process comprises the following steps:

(1) performing vacuum magnetron sputtering by adopting a chromium target (with the purity of 99.99 percent), wherein the vacuum degree is 0.3Pa, and the bias voltage is 120V to form a chromium layer 21;

(2) performing vacuum magnetron sputtering by adopting a chromium target (with the purity of 99.99%) and an aluminum target (with the purity of 99.995%), wherein the vacuum degree is 0.4Pa, and the bias voltage is 110V to form a Cr/Al transition layer 22;

(3) an aluminum film 23 was formed by vacuum magnetron sputtering using an aluminum target (purity 99.995%) under a vacuum degree of 0.3Pa and a bias voltage of 95V, to obtain a cap 1.

Example 8

The difference from embodiment 1 is that a titanium layer, a Ti/Ni transition layer, and a nickel film are sequentially provided inside the space formed by the top plate 11 and the first enclosure wall 12 or inside the top plate 11.

Example 9

The difference from embodiment 3 is that a chromium layer and a nickel film are sequentially provided inside the space formed by the top plate 11 and the first surrounding wall 12 or inside the top plate 11.

Example 10

The difference from embodiment 1 is that a Cr/Al transition layer, a chromium layer and an aluminum film are provided in this order inside the space formed by the top plate 11 and the first wall 12 or inside the top plate 11.

Comparative example 1

The difference from embodiment 2 is that the inside surface of the space formed by the top plate 11 and the first wall 12 is not provided with a chromium layer, a Cr/Al transition layer and an aluminum film.

And (3) testing results:

1) the capped cells of example 3 and comparative example 1 were subjected to the HTHH test, and the results are shown in fig. 7(a), fig. 7(b), and fig. (a), fig. 8(b), from which it can be seen that the capped cells of comparative example 1, which were subjected to the HTHH test, exhibited blackening due to corrosion and black material at the positive terminal of the winding core for 14 days; the capped cell of example 3, HTHH tested for 14 days, showed no corrosion blackening and no black material on the core.

2) The capping battery cells of the embodiment 3 and the comparative example 1 are subjected to storage test under the conditions of 60 ℃ and 90% RH, and the results are shown in fig. 9 and table 1, and analysis shows that the capping battery cell of the comparative example 1 has greatly reduced voltage and failed function along with the time extension; the cap cell of embodiment 3 has stable voltage and normal function.

3) EDS analysis is carried out on the caps disassembled after 28 days of the cap cell cycle + HTHH test in the embodiment 3, the physical photos are shown in figure 10, and the EDS results are shown in figure 11; a physical photograph of the cap before it was assembled into a cell is shown in fig. 12, and EDS results are shown in fig. 13. The result shows that before the cap is assembled into a battery, the EDS analysis of the cap has Al, O, C and Fe elements, the main element is Al element, and the content is 99.38%; after the battery is assembled and the battery is cycled and tested by HTHH for 28 days, the cap EDS analyzes that Al, O and F elements exist, and the main element is still Al element and has the content of about 98.73 percent. From the above analysis, it can be seen that the cap of example 3 has no significant change in the main components and the content thereof after being used as a battery.

4) The ultrasonic welding section analysis chart of the cap and the tab of the embodiment 3 shows that the result is shown in figure 14; the ultrasonic welding section of the cap and the tab of the embodiment 2 is analyzed, and the result is shown in fig. 15. It can be seen from the figure that, in the case of the direct contact between the base material of the cap and the aluminum film in the embodiment 2, the Al plating layer is easily separated from the base material after the positive tab and the cap are welded by ultrasonic welding in the battery processing process, and the risk of the plating layer falling off exists. In example 3, the improvement is obvious by adding a Cr layer, and in addition, the invention discovers that the improvement can be further improved by adding a Cr/Al transition layer (such as example 1 and example 10) on the basis of Cr.

5) The cap of example 3 was tested for plating adhesion by the one hundred grid method, and the results of the bending are shown in fig. 16, which shows that the plating adhesion was tested well by the bending test, and in addition, the invention found that the plating adhesion was better than that of example 3 by the bending test by adding Cr/Al (as in examples 1 and 10) on the basis of Cr.

6) After the caps of example 3 and comparative example 1 were assembled into a battery, rate charging tests were performed under the conditions of constant current and constant voltage charging of 42mA to 4.2V and cutoff current of 1.68mA, and the results are shown in fig. 17, from which it can be seen that the aluminum-plated cap of example 3 can be normally cut off; whereas the cap of comparative example 1 failed to cut off when rate charging was performed.

TABLE 1

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. A cap comprises a cap body and is characterized in that at least one side of the cap body is provided with an anti-corrosion layer.

2. The cap of claim 1, wherein the substrate of the cap body is stainless steel, preferably 304 steel, 304L steel, 316 steel, or 316L steel;

3. The cap according to claim 1 or 2, wherein an M layer is provided between the cap body and the corrosion prevention layer, the M being a metal element;

and/or a transition layer is arranged between the cap body and the anti-corrosion layer, and the transition layer is an M/Al transition layer or an M/Ni transition layer;

preferably, M is a transition metal element, and more preferably at least one of Cr and Ti;

preferably, an aluminum film is arranged on at least one side of the cap body, and an M/Al transition layer and an M layer are sequentially arranged between the cap body and the aluminum film along a direction far away from the aluminum film and towards the cap body;

or at least one side of the cap body is provided with a nickel film, and an M/Ni transition layer and an M layer are sequentially arranged between the cap body and the nickel film along the direction away from the nickel film and towards the cap body.

4. A cap according to any one of claims 1 to 3, characterized in that the thickness of the corrosion protection layer is 100 μm or less, preferably 1 μm to 20 μm;

preferably, the thickness of the M layer is 50 μ M or less, preferably 0.001 μ M to 20 μ M;

preferably, the thickness of the M/Al transition layer and the M/Ni transition layer is independently 50 μ M or less, preferably 0.001 μ M to 20 μ M.

5. A cap according to any one of claims 1 to 4, characterized in that the corrosion protection layer is produced by means of vacuum magnetron sputtering.

6. The cap according to claim 5, characterized in that the aluminum film or the nickel film is prepared by a vacuum magnetron sputtering method;

preferably, in the process of preparing the aluminum film, the vacuum magnetron sputtering adopts an aluminum target material, and the purity of the aluminum target material is preferably more than 90%, and more preferably more than 99.99%;

preferably, an M layer is prepared between the cap body and the aluminum film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an M target material, and the purity of the M target material is preferably more than 90%, and more preferably more than 99.99%;

preferably, an M/Al transition layer is prepared between the aluminum film and the M layer or between the cap body and the aluminum film by adopting a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an aluminum target and an M target, and the purity of the aluminum target and the purity of the M target are preferably more than 90% independently, and further preferably more than 99.99%;

preferably, in the process of preparing the aluminum film, the M/Al transition layer and the M layer, the vacuum degree of the vacuum magnetron sputtering is independently 0.2Pa-0.5 Pa;

preferably, in the process of preparing the aluminum film, the M/Al transition layer and the M layer, the bias voltage of the vacuum magnetron sputtering is independently 80V-130V;

preferably, in the process of preparing the nickel film, the vacuum magnetron sputtering adopts a nickel target material, and the purity of the nickel target material is preferably more than 90%, and more preferably more than 99.99%;

preferably, an M layer is prepared between the cap body and the nickel film by a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts an M target material, and the purity of the M target material is preferably more than 90%, and more preferably more than 99.99%;

preferably, an M/Ni transition layer is prepared between the nickel film and the M layer or the M/Ni transition layer is prepared between the cap body and the aluminum film by adopting a vacuum magnetron sputtering method, wherein the vacuum magnetron sputtering method adopts a nickel target material and an M target material, and the purity of the nickel target material and the purity of the M target material are preferably more than 90% independently, and further preferably more than 99.99%;

preferably, in the process of preparing the nickel film, the M/Ni transition layer and the M layer, the vacuum degree of the vacuum magnetron sputtering is independently 0.2Pa-0.5 Pa;

preferably, in the process of preparing the nickel film, the M/Ni transition layer and the M layer, the bias voltage of the vacuum magnetron sputtering is independently 80V-130V;

preferably, the thickness of the anti-corrosion layer prepared by the vacuum magnetron sputtering method is less than or equal to 100 μm, and preferably 1 μm to 20 μm;

7. A battery, characterized in that the battery comprises a battery core, a bottom shell and a cap according to any one of claims 1 to 6, a containing cavity for containing the battery core is formed between the bottom shell and the cap, the bottom shell and the cap are insulated and sealed by a sealing member, and the cap is provided with an anti-corrosion layer at one side of the containing cavity.

8. The battery of claim 7, wherein the cap comprises a top plate and a first surrounding wall surrounding one side of the top plate, the bottom shell comprises a bottom plate and a second surrounding wall surrounding one side of the bottom plate, and the first surrounding wall is covered outside the second surrounding wall or the second surrounding wall is covered outside the first surrounding wall;

9. The battery of claim 7 or 8, wherein the battery core comprises a pole piece and a diaphragm, the pole piece comprises a positive pole piece and a negative pole piece, and the diaphragm is positioned between the positive pole piece and the negative pole piece;

preferably, the pole piece comprises a current collector and an active material coated on the current collector;

preferably, a positive tab is arranged on the positive plate and connected with the cap;

preferably, the material of the positive tab is selected from aluminum or nickel;

preferably, the battery cell is a winding battery cell, the diaphragm has an isolation portion extending to two ends of the negative plate along an axial direction of the winding battery cell, and the isolation portion is used for electrically insulating a tab of the winding battery cell and an end face of the winding battery cell;

preferably, the battery cell is a laminated battery cell, and the diaphragm has an isolation part extending to an edge of a negative plate of the laminated battery cell, and the isolation part is used for electrically insulating a tab of the laminated battery cell from an end face of the laminated battery cell;

preferably, the diameter-height ratio of the battery is more than or equal to 1, preferably more than 1;

preferably, the current collector contains a void foil area uncoated with active material, the void foil area forming an extension, the extension forming a tab;

10. The battery of claim 9, wherein the cell further comprises a reinforcement that wraps around the overlap location of the extension.