Composite current collector with welding reservation and preparation method thereof

Abstract

The invention provides a composite current collector with reserved welding and a preparation method thereof, the composite current collector with reserved welding comprises a conductive substrate, the conductive substrate comprises a current collector coating part and a reserved welding part, the thickness of the reserved welding part is greater than that of the current collector coating part, and the thickness of the reserved welding part is greater than that of the current collector coating part. The upper surface of the welding reserved part is flush with the upper surface of the current collector coating part, the lower surface of the welding reserved part is higher than the lower surface of the current collector coating part, and the lower surface of the current collector coating part is covered with a non-conductive base layer. And conductive coatings are arranged on the lower surface of the non-conductive base layer and the lower surface of the welding reserved part. Through the arrangement, the conductive substrate is made of the pure metal foil, and meanwhile, the welding reserved part is also made of the pure metal foil, so that a tab and an adapter plate do not need to be welded again when a battery is prepared, the welding reserved part of the composite current collector can be directly cut into strips, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of current collectors, and in particular to a composite current collector with welding reservation and a preparation method thereof. Background Art

[0002] The current collector is one of the indispensable electrode materials for lithium-ion batteries. It has the important functions of carrying active substances (carrying capacity) and collecting microcurrents (conductivity). Thinning and functionalization are the main development directions of current collectors. The 8-9um Alfoil current collector and the 4-5um Cu foil current collector have almost reached the ultimate level of manufacturability of lithium-ion batteries. Further thinning of the current collector leads to reduced strength and difficulty in mass application. Although functionalized current collectors such as carbon coating, LFP, and ceramics can improve adhesion, internal resistance, safety performance, etc., there are still some negative effects, such as higher process control requirements, increased costs, or reduced energy density. Composite current collectors integrate the characteristics of thin and light and high-safety current collectors and have been widely studied in recent years.

[0003] When the composite current collector is used in a battery, when it is punctured, the base film of the composite current collector will wrap up the end of the punctured object to prevent the positive and negative electrodes from directly contacting and forming a short circuit. In the current situation where electric vehicles and other vehicles frequently spontaneously combust, the application of composite current collectors is accelerating. In the process of preparing batteries with composite current collectors, it is necessary to weld the pole ears to conduct the current gathered by the composite current collector from the pole ears to the electrical device. Currently, the welding pole ears are clamped at the edge of the end of the composite current collector with pole ears and adapters, and then welded. The base film of the composite current collector is not conductive, and the base film will affect the conductive effect after welding, and the additional addition of pole ears and adapters will greatly increase the weight and cost of the battery. Therefore, the existing technology needs to be improved and improved. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a composite current collector with welding reservation and a preparation method thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a composite current collector with a welding reservation, comprising a conductive substrate, wherein the conductive substrate comprises a current collector coating portion and a welding reservation portion, the thickness of the welding reservation portion is greater than the thickness of the current collector coating portion, the upper surface of the welding reservation portion is flush with the upper surface of the current collector coating portion, the lower surface of the welding reservation portion is higher than the lower surface of the current collector coating portion, the lower surface of the current collector coating portion is covered with a non-conductive base layer, and a conductive coating is provided on the lower surface of the non-conductive base layer and on the lower surface of the welding reservation portion.

[0007] In a preferred embodiment, for the composite current collector with welding reservation, the side surface of the non-conductive base layer is connected to the welding reservation portion, and the lower surface of the non-conductive base layer is flush with the lower surface of the welding reservation portion.

[0008] In a preferred embodiment, the composite current collector having a reservation for welding is a conductive substrate which is a metal foil.

[0009] In a preferred embodiment, the composite current collector reserved for welding and the conductive substrate have a thickness of 6um-20um.

[0010] In a preferred embodiment, the composite current collector with welding reservation has a notch structure etched on the lower surface of the current collector coating portion.

[0011] In a preferred embodiment, the composite current collector having a welding reserve is provided, the notch structure is a mesh notch structure, and the notch depth of the notch structure is 100nm-1000nm.

[0012] In a preferred embodiment, the composite current collector having a welding reserve is provided, and the non-conductive layer is a polymer film layer.

[0013] In a preferred embodiment, the composite current collector reserved for welding has a thickness of 1 um to 4 um for the non-conductive base layer.

[0014] In a preferred embodiment, the composite current collector with welding reservation is provided with a lower coating between the non-conductive base layer and the conductive coating, the lower coating is aluminum oxide, silicon nitride, silicon carbide, copper alloy, aluminum alloy, nickel alloy or titanium alloy coating, the conductive coating is a metal coating, the conductive coating is the same thickness as the current collector coating portion of the conductive substrate, the conductive coating is aluminum, copper, titanium, nickel, aluminum alloy, titanium alloy, nickel alloy or aluminum alloy coating, and the conductive substrate is aluminum, copper, titanium, nickel, aluminum alloy, titanium alloy, nickel alloy or aluminum alloy substrate.

[0015] The present invention also provides a method for preparing the composite current collector with welding reservation as described above, comprising:

[0016] Taking a conductive substrate, the conductive substrate comprising a current collector coating portion and a welding reserved portion, and performing a thinning process on the current collector coating portion of the conductive substrate;

[0017] Covering a non-conductive base layer on the lower surface of the current collector coating portion;

[0018] A conductive coating is plated on the lower surface of the non-conductive base layer and the lower surface of the welding reserved portion.

[0019] Compared with the prior art, the present invention provides a composite current collector with welding reservation and a preparation method thereof, wherein the composite current collector with welding reservation comprises a conductive substrate, the conductive substrate comprises a current collector coating portion and a welding reservation portion, the thickness of the welding reservation portion is greater than the thickness of the current collector coating portion, the upper surface of the welding reservation portion is flush with the upper surface of the current collector coating portion, the lower surface of the welding reservation portion is higher than the lower surface of the current collector coating portion, the lower surface of the current collector coating portion is covered with a non-conductive base layer, and a conductive coating is arranged on the lower surface of the non-conductive base layer and the lower surface of the welding reservation portion. Through such a setting, the present invention, since the conductive substrate is a pure metal foil and the welding reservation portion is also a pure metal foil, when preparing the battery, it is not necessary to weld the pole ear and the adapter again, and the welding reservation portion of the composite current collector can be directly cut into strips, and then welded with external devices such as a busbar, which is conducive to reducing multiple processes, thereby helping to improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] Figure 1 A schematic structural diagram of a conductive substrate with a composite current collector reserved for welding provided by the present invention.

[0022] Figure 2 A schematic diagram of the structure of a composite current collector with welding reservation provided by the present invention.

[0023] Figure 3 A schematic diagram of the notched structure of a conductive substrate with a composite current collector reserved for welding provided by the present invention.

[0024] Description of Figure Numbers:

[0025] Conductive substrate 100

[0026] Current collector coating portion 110

[0027] Welding reserved portion 120

[0028] Non-conductive base layer 200

[0029] Conductive coating 300 DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] like Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a composite current collector with welding reservation and a preparation method thereof, wherein the composite current collector with welding reservation comprises a conductive substrate 100, the conductive substrate 100 comprises a current collector coating portion 110 and a welding reservation portion 120, the thickness of the welding reservation portion 120 is greater than the thickness of the current collector coating portion 110, the upper surface of the welding reservation portion 120 is flush with the upper surface of the current collector coating portion 110, the lower surface of the welding reservation portion 120 is higher than the lower surface of the current collector coating portion 110, the lower surface of the current collector coating portion 110 is covered with a non-conductive base layer 200, and a conductive coating 300 is provided on the lower surface of the non-conductive base layer 200 and the lower surface of the welding reservation portion 120. With such an arrangement, in the present invention, since the conductive substrate 100 is made of pure metal foil and the welding reserved portion 120 is also made of pure metal foil, there is no need to weld the tabs and the adapter again when preparing the battery. The welding reserved portion 120 of the composite current collector can be directly cut into strips and then welded to external devices such as the busbar, which is conducive to reducing multiple working steps and thus helping to improve production efficiency.

[0034] The composite current collector embodiment provided by the present invention includes a non-conductive base layer 200, which is generally a polymer film layer. The composite current collector embodiment provided by the present invention also includes upper and lower surfaces arranged in the thickness direction of the polymer film layer, and metal layers are arranged on the upper and lower surfaces of the polymer film layer, which are respectively a conductive substrate 100 and a conductive coating 300. In this embodiment, a metal conductive substrate 100 and a metal conductive coating 300 are used. The metal conductive substrate 100 has a welding reservation 120 and a current collector coating 110. The welding reservation 120 is located on one side of the composite current collector in the width direction, and the remaining part of the current collector is the current collector coating 110. The thickness of the welding reservation 120 for the electrode tab welding of the metal conductive substrate 100 is higher than the current collector coating 110, and a polymer film layer is arranged on the current collector coating 110, and the thickness of the polymer film layer can be the same as the difference between the thickness of the welding reservation 120 and the thickness of the current collector coating 110. The metal conductive coating 300 covers the polymer film layer and the welding reservation 120, wherein the metal conductive substrate 100 is a pure metal foil. With such a configuration, since the metal conductive substrate 100 is a pure metal foil, the welding reservation 120 is also a pure metal foil. When preparing the battery, there is no need to weld the tabs and the adapter again. The welding reservation 120 can be directly cut into strips and then welded to the busbar and other devices, which greatly reduces the process and improves production efficiency. The polymer film layer of this embodiment can be a film made of any non-conductive material. The polymer film layer of this embodiment of the present invention can be a film formed by one or more of polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polypropylene, acrylonitrile-butadiene-styrene copolymer, polyvinyl alcohol, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, sodium polystyrene sulfonate, polyacetylene, silicone rubber, polyformaldehyde, polyphenylene ether, polyphenylene sulfide, polyethylene glycol, polysulfur nitride polymer materials, polyphenylene, polypyrrole, polyaniline, polythiophene, polypyridine, cellulose, starch, protein, epoxy resin, and phenolic resin.

[0035] Further, in the composite current collector with welding reservation provided by the present invention, the side of the non-conductive base layer 200 is connected to the welding reservation portion 120, and the lower surface of the non-conductive base layer 200 is flush with the lower surface of the welding reservation portion 120. Further, in the composite current collector with welding reservation provided by the present invention, the conductive substrate 100 is a metal foil. Further, in the composite current collector with welding reservation provided by the present invention, the thickness of the conductive substrate 100 is 6um-20um, and the thickness of the conductive substrate 100 can be selected as a metal foil of 12um.

[0036] Furthermore, the composite current collector provided by the present invention has a welding reserve, and a notch structure is etched on the lower surface of the current collector coating portion 110. Further, the composite current collector provided by the present invention has a welding reserve, and the notch structure is a mesh notch structure, and the notch depth of the notch structure is 100nm-1000nm. That is to say, in the present invention, notches can also be etched on the conductive substrate 100, that is, on the side of the pure metal foil mentioned above facing the polymer film layer, and the depth of these notches is 100nm-1000nm. Then a polymer film layer is formed on the side of the conductive substrate 100 where the notch is provided. In this way, the polymer material part is formed on the conductive substrate 100, which improves the bonding force between the conductive substrate 100 and the polymer film layer. These notches are preferably a cross-mesh structure, and such a structure has better bonding force, and at the same time, the mass of the composite current collector can be reduced.

[0037] Further, the composite current collector provided by the present invention has a welding reserve, and the non-conductive layer is a polymer film layer. Further, the composite current collector provided by the present invention has a welding reserve, and the thickness of the non-conductive base layer 200 is 1um-4um. Further, the composite current collector provided by the present invention has a welding reserve, and a lower coating is provided between the non-conductive base layer 200 and the conductive coating 300, and the lower coating is aluminum oxide, silicon nitride, silicon carbide, copper alloy, aluminum alloy, nickel alloy or titanium alloy coating, and the conductive coating 300 is a metal coating, and the conductive coating 300 has the same thickness as the current collector coating portion 110 of the conductive substrate 100, and the conductive coating 300 is aluminum, copper, titanium, nickel, aluminum alloy, titanium alloy, nickel alloy or aluminum alloy coating, and the conductive substrate 100 is aluminum, copper, titanium, nickel, aluminum alloy, titanium alloy, nickel alloy or aluminum alloy substrate. The thickness of the polymer film layer can be 1um-4um, and can be set to a polymer film layer with a thickness of 3um. Among them, a lower coating layer can also be set between the conductive coating layer 300 and the polymer film layer. For example, a coating layer such as aluminum oxide, silicon nitride, silicon carbide, copper alloy, aluminum alloy, nickel alloy, titanium alloy, etc., this layer is called a lower coating layer, and the function of the lower coating layer is to improve the bonding force between the lower metal layer and the polymer film layer (that is, the polymer material). The material of the conductive coating layer 300 can be aluminum, copper, titanium, nickel, or aluminum alloy, titanium alloy, nickel alloy or aluminum alloy. Preferably, the material of the conductive base layer and the material of the conductive coating layer 300 can be consistent.

[0038] The present invention also provides a method for preparing the composite current collector with welding reservation as described above, comprising:

[0039] S100, taking a conductive substrate 100, wherein the conductive substrate 100 comprises a current collector coating portion 110 and a welding reserved portion 120, and performing a thinning process on the current collector coating portion 110 of the conductive substrate 100;

[0040] S200, coating a non-conductive base layer 200 on the lower surface of the current collector coating portion 110;

[0041] S300 , a layer of conductive coating 300 is plated on the lower surface of the non-conductive base layer 200 and the lower surface of the welding reserved portion 120 .

[0042] Specifically, when preparing the composite current collector with welding reservation of the present invention, first take a metal foil (that is, a conductive substrate 100), the thickness of which can be 6um-20um, such as 12um; then thin a part of the metal foil, and etching, electroplating or other existing thinning methods can be used, so that one side of the metal foil in the width direction is not thinned, while other positions are thinned, and the thickness of the thinned part is 1um-3um, such as 3um. At this time, the thinned part is the current collector coating part 110, and the position that is not thinned is the welding reservation part 120 of the current collector; then spray or apply a layer of non-conductive polymer material on the current collector coating part 110 to form the polymer film layer mentioned above. The polymer material used in the polymer film layer can be PP material, PET material or PI material, etc., and the thickness of the polymer material is the welding reservation part 120 is higher than the thickness of the current collector coating part 110; wait for the formed polymer material to solidify; after solidification, the above material is vacuum evaporated once to form the conductive coating 300 mentioned above. The thickness of the conductive coating 300 is equal to the thickness of the current collector coating portion 110 of the conductive substrate 100 after thinning.

[0043] In the present invention, roughness treatment can also be performed on the surface of the polymer material to improve the roughness of the polymer surface. Specifically, plasma treatment and other methods can be used, and then a conductive coating 300 is formed on the surface of the polymer material. The main purpose is to improve the bonding strength between the lower metal layer and the polymer material.

[0044] The composite current collector prepared in this way has many benefits that existing production methods do not have. First, the process of welding the pole ear can be reduced; second, the welding reserved part 120 of the current collector is pure metal, which can improve the current capacity of this part and reduce heat generation; third, the production cost of the composite current collector can be reduced. At present, a vacuum coating equipment costs up to several million, and it costs a lot to draw a vacuum and run it once; fourth, the void problem in the production of composite current collector can be completely eliminated. The voids are mostly caused by the film being burned through by high-temperature particles when the metal layer is formed on the film for the first time. The conductive substrate 100 of the present application is not formed by vacuum coating, so there will be no pinholes (also known as holes); fifth, since the conductive substrate 100 and the conductive coating 300 are not formed by the same process, in the final composite current collector, for example, after winding, there will be no adhesion between the conductive substrate 100 and the conductive coating 300, which solves this prominent problem; sixth, the polymer film layer of the composite current collector of the present invention is coated, and the thickness can be adjusted according to actual conditions, so that the thickness of the film can be reduced, and the production of ultra-thin composite current collectors can be achieved.

[0045] In summary, the present invention provides a composite current collector with welding reservation and a preparation method thereof, wherein the composite current collector with welding reservation comprises a conductive substrate, the conductive substrate comprises a current collector coating portion and a welding reservation portion, the thickness of the welding reservation portion is greater than the thickness of the current collector coating portion, the upper surface of the welding reservation portion is flush with the upper surface of the current collector coating portion, the lower surface of the welding reservation portion is higher than the lower surface of the current collector coating portion, the lower surface of the current collector coating portion is covered with a non-conductive base layer, and a conductive coating is arranged on the lower surface of the non-conductive base layer and the lower surface of the welding reservation portion. Through such a setting, the present invention, since the conductive substrate is a pure metal foil and the welding reservation portion is also a pure metal foil, when preparing the battery, there is no need to weld the pole ear and the adapter again, and the welding reservation portion of the composite current collector can be directly cut into strips, and then welded with external devices such as a busbar, which is conducive to reducing multiple processes, thereby helping to improve production efficiency.

[0046] Moreover, the composite current collector prepared in this way has many benefits that are not available in existing production methods. First, the process of welding the pole ear can be reduced; second, the welding reserved part of the current collector is pure metal, which can improve the flow capacity of this part and reduce heat generation; third, the production cost of the composite current collector can be reduced. At present, a vacuum coating device costs millions of yuan, and it costs a lot of money to draw a vacuum once; fourth, the void problem in the production of the composite current collector can be completely eliminated. The voids are mostly generated when the metal layer is formed on the film for the first time, and the film is burned through by high-temperature particles. However, the conductive substrate of the present application is not formed by vacuum coating, so there will be no pinholes (also called holes); fifth, because the conductive substrate and the conductive coating are not formed by the same process, in the final composite current collector, for example, after winding, the conductive substrate and the conductive coating will not stick together, which solves this outstanding problem; sixth, the polymer film layer of the composite current collector of the present invention is coated, and the thickness can be adjusted according to the actual situation, so the thickness of the film can be reduced, and the production of ultra-thin composite current collectors can be achieved.

[0047] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A composite current collector with welding reservation, characterized in that: It includes a conductive substrate, which includes a current collector coating portion and a welding reserved portion, the thickness of the welding reserved portion is greater than the thickness of the current collector coating portion, the upper surface of the welding reserved portion is flush with the upper surface of the current collector coating portion, the lower surface of the welding reserved portion is higher than the lower surface of the current collector coating portion, the lower surface of the current collector coating portion is covered with a non-conductive base layer, and a conductive coating is provided on the lower surface of the non-conductive base layer and the lower surface of the welding reserved portion.

2. The composite current collector with welding reservation according to claim 1, characterized in that: The side surface of the non-conductive base layer is connected to the welding reserved portion, and the lower surface of the non-conductive base layer is flush with the lower surface of the welding reserved portion.

3. The composite current collector with welding reservation according to claim 1, characterized in that: The conductive substrate is a metal foil.

4. The composite current collector with welding reservation according to claim 2, characterized in that: The thickness of the conductive substrate is 6um-20um.

5. The composite current collector with welding reserve according to claim 1, characterized in that: A notch structure is etched on the lower surface of the current collector coating portion.

6. The composite current collector with welding reservation according to claim 5, characterized in that: The notch structure is a mesh-like notch structure, and the notch depth of the notch structure is 100nm-1000nm.

7. The composite current collector with welding reservation according to claim 1, characterized in that: The non-conductive layer is a polymer film layer.

8. The composite current collector with welding reserve according to claim 7, characterized in that: The thickness of the non-conductive base layer is 1um-4um.

9. The composite current collector with welding reserve according to any one of claims 1 to 8, characterized in that: An undercoat layer is arranged between the non-conductive base layer and the conductive coating layer, and the undercoat layer is a coating of aluminum oxide, silicon nitride, silicon carbide, copper alloy, aluminum alloy, nickel alloy or titanium alloy, and the conductive coating layer is a metal coating. The conductive coating layer has the same thickness as the current collector coating portion of the conductive substrate, and the conductive coating layer is a coating of aluminum, copper, titanium, nickel, aluminum alloy, titanium alloy, nickel alloy or aluminum alloy, and the conductive substrate is an aluminum, copper, titanium, nickel, aluminum alloy, titanium alloy, nickel alloy or aluminum alloy substrate.

10. A method for preparing a composite current collector with welding reservation as claimed in any one of claims 1 to 9, characterized in that: include: Taking a conductive substrate, the conductive substrate comprising a current collector coating portion and a welding reserved portion, and performing a thinning process on the current collector coating portion of the conductive substrate; Covering a non-conductive base layer on the lower surface of the current collector coating portion; A conductive coating is plated on the lower surface of the non-conductive base layer and the lower surface of the welding reserved portion.

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