Preparation Method and Application of a Functional Current Collector with Low Thermal Shrinkage and High Tensile Strength

Abstract

The present invention relates to the technical field of batteries, and specifically to a preparation method and application of a functional current collector with low thermal shrinkage and high tensile strength. In the present invention, a thermal shrinkage transition layer and a copper layer are sequentially magnetron sputtered on the surface of a base film, and then a copper layer is electroplated to prepare a functional current collector. The functional current collector prepared by the present invention can effectively solve the problems of large thermal deformation amount and large residual stress of the functional current collector, and at the same time can also improve the overall strength and stability of the functional current collector, so it has broad application prospects in the technical field of batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and specifically to a preparation method and application of a functional current collector with low thermal shrinkage and high tensile strength. Background Art

[0002] With the rapid development of new energy and electronic technologies, the cycle life, safety performance, energy density, etc. of batteries have become top priorities. As a very important part of the battery, the current collector is used to collect the current generated by the battery active substances so as to form a larger current for external output. The quality of its performance will directly affect the cycle life, energy density, safety, etc. of the battery. Currently, copper foils and aluminum foils are mostly used as current collectors for the positive and negative electrode sheets in lithium batteries and sodium batteries. Such current collectors have high costs and weights, which are not conducive to the control of battery costs and the improvement of energy density. In this regard, the foil current collector has obvious advantages compared with traditional foil materials. The foil current collector is usually a "sandwich" structure, with a polymer polymer layer in the inner layer and metal conductive layers on both sides. Since the metal layer on the surface of the current collector is thin and the polymer layer inside is light, the overall weight of the current collector can be well reduced, thereby increasing the energy density of the lithium-ion battery; at the same time, the relatively thin metal layer on the surface of the current collector is more likely to break than the current collector of traditional foil materials when the lithium-ion battery undergoes thermal runaway, thereby isolating the connection between the active substances and the current collector and preventing the continuous progress of the thermal runaway of the lithium-ion battery. However, although the foil current collector has the advantages of low cost and light weight, a large amount of heat will be generated during the processing of coating, hot pressing, etc. of the current collector or when the battery is made into a finished product and the battery is cycled, resulting in excessive thermal shrinkage of the current collector, large thermal deformation, volume change, thus causing film surface deformation and copper layer peeling off, seriously reducing the energy density and cycle life of the battery, and also bringing safety problems to the battery. At the same time, the low tensile strength of the current collector will cause it to break passively during subsequent manufacturing or application processes, thus affecting the performance of the current collector.

[0003] In order to overcome the defects of the prior art, the present invention provides a preparation method and application of a functional current collector with low thermal shrinkage and high tensile strength. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a functional current collector with low thermal shrinkage and high tensile strength to solve the problems in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A functional current collector with low thermal shrinkage and high tensile strength, comprising a base film, a thermal shrinkage transition layer formed on the surface of the base film, and a metal layer formed on the surface of the thermal shrinkage transition layer; wherein the thermal shrinkage rate of the thermal shrinkage transition layer ranges between that of the metal layer and the base film, and the thermal shrinkage rate of the thermal shrinkage transition layer is less than that of the base film.

[0007] Preferably, the material of the thermal shrinkage transition layer is a high-entropy alloy, specifically TaNbHfZrTi, TaNbHfZrTiMo 0.75 , MoNbTaTiV, AlMgLiZnCu, AlMgZnCuSi, AlZrTiNbMo, CoCrFeMnNi, NbMoTaWVCr, ZrTiHfV 0.5 Nb 0.5 C 0.2 , TaNbHfZrTiMoW, VNbMoTaW, Ti 4.8 Zr2Hf 1.5 AlNb 0.7 , Ti3Al2V2Nb2Mo; wherein for TaNbHfZrTi, MoNbTaTiV, AlMgLiZnCu, AlMgZnCuSi, AlZrTiNbMo, CoCrFeMnNi, NbMoTaWVCr, TaNbHfZrTiMoW, VNbMoTaW, the mass ratio of each metal element is 1:1:1:1:1; for TaNbHfZrTiMo 0.75 it means the mass ratio of each metal element is 1:1:1:1:1:0.75; for ZrTiHfV 0.5 Nb 0.5 C 0.2 it means the mass ratio of each metal element is 1:1:1:0.5:0.5:0.2; for Ti 4.8 Zr2Hf 1.5 AlNb 0.7 it means the mass ratio of each metal element is 4.8:2:1.5:1:0.7; for Ti3Al2V2Nb2Mo, it means the mass ratio of each metal element is 3:2:2:2:1.

[0008] Preferably, the metal layer is copper or a copper alloy.

[0009] Preferably, the base film material is any one of polypropylene, polyethylene terephthalate, polyimide, polyethylene naphthalate, polyethersulfone, polyethylene, polyvinyl chloride, polystyrene, polycarbonate, polyvinylidene fluoride.

[0010] A preparation method of a functional current collector with low thermal shrinkage and high tensile strength, comprising the following steps:

[0011] S1: Take the base film, deposit a heat-shrinkable transition layer on the surface of the base film by magnetron sputtering process, and then use copper or copper alloy as the target to magnetron sputter and deposit a copper or copper alloy layer on the surface of the heat-shrinkable transition layer;

[0012] S2: Electroplate and thicken the copper or copper alloy on the surface of the copper or copper alloy layer in S1 to form a metal layer, and obtain a functional current collector.

[0013] Preferably, in step S1, the thickness of the base film is 4.0 - 4.5 μm.

[0014] Preferably, in step S1, the thickness of the heat-shrinkable transition layer is 5 - 15 nm.

[0015] Preferably, in step S1, the thickness of the copper or copper alloy layer is 60 - 70 nm.

[0016] Preferably, in step S2, the thickness of the electroplated and thickened copper or copper alloy is 1 - 2 μm.

[0017] The battery prepared from the functional current collector with low heat shrinkage and high tensile strength includes a cathode, an anode, a housing, and an electrolyte layer disposed between the cathode and the anode; wherein the cathode includes a functional current collector and an active material layer.

[0018] Advantages of the present invention:

[0019] In the present invention, a heat-shrinkable transition layer and a copper layer are successively magnetron sputtered on the surface of the base film, and then the copper layer is electroplated to prepare a functional current collector. The feature of the present invention is that the present invention provides a functional current collector with low heat shrinkage and high tensile strength. By adding a heat-shrinkable transition layer between the metal layer and the inner polymer layer, the heat shrinkage deformation amount of the functional current collector during cyclic application can be reduced, effectively solving the problems of large heat deformation amount and large residual stress of the functional current collector, without affecting the conductivity of the functional current collector, and at the same time improving the overall strength and stability of the functional current collector.

[0020] Among them, the material of the heat-shrinkable transition layer is a high-entropy alloy. Using a high-entropy alloy has the following advantages: on the one hand, the composition of the high-entropy alloy contains multiple high-melting-point metals, making it have a high melting point and thermal stability, and the functional current collector will not generate large deformations due to heating or cooling during processing such as magnetron sputtering, and the film layer of the functional current collector will not deform and peel off due to residual stress during application after processing. On the other hand, due to its uniformly mixed atomic structure and the combined action of multiple groups of elements, the high-entropy alloy has a high anti-deformation ability and mechanical strength, can withstand greater external tensile or compressive forces without easily undergoing plastic deformation, helps to reduce the deformation amount, and improves the tensile strength of the functional current collector. Description of the Drawings

[0021] The accompanying drawings are used to provide a further understanding of the present invention and form a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the accompanying drawings:

[0022] Figure 1 is a structural diagram of the functional current collector of the present invention;

[0023] In the figure: 1: base film, 2: heat-shrinkable transition layer, 3: metal layer. Detailed embodiments

[0024] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0025] Source of raw materials:

[0026] Polypropylene film: provided by Anhui Tongfeng Electronics Co., Ltd., model MRPP; AlMgLiZnCu, is a target provided by Lavoisier (Beijing) New Materials Technology Co., Ltd.; AlZrTiNbMo, is a target provided by Plansee SE; CoCrFeMnNi, is a target provided by Plansee SE; ZrTiHfV 0.5 Nb 0.5 C 0.2 , is a target provided by Lavoisier (Beijing) New Materials Technology Co., Ltd.; Ti3Al2V2Nb2Mo, is a target provided by Baoji Lihua Metal Materials Co., Ltd.; Cr20Ni80, is a target provided by Lavoisier (Beijing) New Materials Technology Co., Ltd.

[0027] Example 1: S1: Use a 4.5-μm polypropylene film as the base film 1, deposit a heat-shrinkable transition layer 2 (AlMgLiZnCu layer) on the surface of the base film 1 by magnetron sputtering process, and then use copper as the target to magnetron sputter and deposit a copper layer on the surface of the heat-shrinkable transition layer 2; wherein the thickness of the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) is 10 nm, and the thickness of the copper layer is 60 nm; the magnetron sputtering process is as follows: the temperature of the base film is maintained at -20 °C, the sputtering pressure is maintained at 0.5 Pa, the power is 10 KW, and a 10-nm-thick AlMgLiZnCu layer is deposited on both the upper and lower surfaces of the base film at a speed of 4 m / min; then set the power of the copper target to 15 KW, and deposit a 60-nm-thick copper layer on both the upper and lower surfaces of the base film at a speed of 4 m / min;

[0028] S2: Electroplate the copper layer on the surface of S1 to increase the thickness of copper, forming the metal layer 3 to obtain the functional current collector; wherein the thickness of the electroplated copper is 1 μm; the electroplating process is as follows: place the film material with the sputtered copper layer in a water plating tank with the electroplating solution at a constant temperature of 22 °C, wherein the electroplating solution composition is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive; the copper plating additive includes 20 mg / L of sodium polydithiopropanesulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0029] Example 2: Replace the heat shrinkable transition layer 2 (AlMgLiZnCu layer) with an AlZrTiNbMo layer, and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1, deposit the heat shrinkable transition layer 2 (AlZrTiNbMo layer) on the surface of the base film 1 by magnetron sputtering, and then use copper as the target to magnetron sputter and deposit a copper layer on the surface of the heat shrinkable transition layer 2; wherein the thickness of the heat shrinkable transition layer 2 (AlZrTiNbMo layer) is 10 nm, and the thickness of the copper layer is 60 nm; the magnetron sputtering process is as follows: keep the temperature of the base film at -20 °C, the sputtering pressure at 0.5 Pa, the power at 10 KW, and deposit a 10-nm-thick AlZrTiNbMo layer on both sides of the base film at a speed of 4 m / min; then set the copper target power at 15 KW and deposit a 60-nm-thick copper layer on both sides of the base film at a speed of 4 m / min.

[0030] S2: Electroplate the copper layer on the surface of S1 to increase the thickness of copper, forming the metal layer 3 to obtain the functional current collector; wherein the thickness of the electroplated copper is 1 μm; the electroplating process is as follows: place the film material with the sputtered copper layer in a water plating tank with the electroplating solution at a constant temperature of 22 °C, wherein the electroplating solution composition is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive; the copper plating additive includes 20 mg / L of sodium polydithiopropanesulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0031] Example 3: Replace the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) with a CoCrFeMnNi layer, and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1. Deposit the heat-shrinkable transition layer 2 (CoCrFeMnNi layer) on the surface of the base film 1 by magnetron sputtering. Then, use copper as the target and magnetron sputter to deposit a copper layer on the surface of the heat-shrinkable transition layer 2. The thickness of the heat-shrinkable transition layer 2 (CoCrFeMnNi layer) is 10 nm, and the thickness of the copper layer is 60 nm. The magnetron sputtering process is as follows: Keep the base film temperature at -20 °C, the sputtering gas pressure at 0.5 Pa, the power at 10 KW, and deposit a 10-nm-thick CoCrFeMnNi layer on both sides of the base film at a speed of 4 m / min. Then, set the copper target power to 15 KW and deposit a 60-nm-thick copper layer on both sides of the base film at a speed of 4 m / min.

[0032] S2: Electroplate the copper layer on the surface of S1 to thicken the copper and form the metal layer 3 to obtain the functional current collector. The thickness of the electroplated thickened copper is 1 μm. The electroplating process is as follows: Place the film material with the sputtered copper layer in a water plating tank with the electroplating solution at a constant temperature of 22 °C. The electroplating solution composition is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive. The copper plating additive includes 20 mg / L of sodium polydithiopropane sulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0033] Example 4: Replace the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) with a ZrTiHfV 0.5 Nb 0.5 C 0.2 layer, and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1. Deposit the heat-shrinkable transition layer 2 (ZrTiHfV 0.5 Nb 0.5 C 0.2 layer) on the surface of the base film 1 by magnetron sputtering. Then, use copper as the target and magnetron sputter to deposit a copper layer on the surface of the heat-shrinkable transition layer 2. The thickness of the heat-shrinkable transition layer 2 (ZrTiHfV 0.5 Nb 0.5 C 0.2 layer) is 10 nm, and the thickness of the copper layer is 60 nm. The magnetron sputtering process is as follows: Keep the base film temperature at -20 °C, the sputtering gas pressure at 0.5 Pa, the power at 10 KW, and deposit a 10-nm-thick ZrTiHfV 0.5 Nb 0.5 C 0.2 layer on both sides of the base film at a speed of 4 m / min. Then, set the copper target power to 15 KW and deposit a 60-nm-thick copper layer on both sides of the base film at a speed of 4 m / min.

[0034] S2: Electroplate the copper layer on the surface of S1 to increase the thickness of copper, forming the metal layer 3 to obtain the functional current collector; wherein the thickness of the electroplated and thickened copper is 1 μm; the electroplating process is as follows: place the film material with the sputtered copper layer in a water plating tank with the electroplating solution at a constant temperature of 22 °C, wherein the electroplating solution composition is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive; the copper plating additive includes 20 mg / L of sodium polydithiopropane sulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0035] Example 5: Replace the heat shrinkable transition layer 2 (AlMgLiZnCu layer) with a Ti3Al2V2Nb2Mo layer, and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1, deposit the heat shrinkable transition layer 2 (Ti3Al2V2Nb2Mo layer) on the surface of the base film 1 by magnetron sputtering process, and then use copper as the target to magnetron sputter and deposit a copper layer on the surface of the heat shrinkable transition layer 2; wherein the thickness of the heat shrinkable transition layer 2 (Ti3Al2V2Nb2Mo layer) is 10 nm, and the thickness of the copper layer is 60 nm; the magnetron sputtering process is as follows: keep the temperature of the base film at -20 °C, keep the sputtering pressure at 0.5 Pa, the power is 10 KW, and deposit a 10-nm-thick Ti3Al2V2Nb2Mo layer on the upper and lower surfaces of the base film at a speed of 4 m / min; then set the copper target power to 15 KW and deposit a 60-nm-thick copper layer on the upper and lower surfaces of the base film at a speed of 4 m / min.

[0036] S2: Electroplate the copper layer on the surface of S1 to increase the thickness of copper, forming the metal layer 3 to obtain the functional current collector; wherein the thickness of the electroplated and thickened copper is 1 μm; the electroplating process is as follows: place the film material with the sputtered copper layer in a water plating tank with the electroplating solution at a constant temperature of 22 °C, wherein the electroplating solution composition is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive; the copper plating additive includes 20 mg / L of sodium polydithiopropane sulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0037] Example 6: Modify the thickness of the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) to 5 nm, and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1, and deposit the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) on the surface of the base film 1 by magnetron sputtering. Then, use copper as the target and magnetron sputter to deposit a copper layer on the surface of the heat-shrinkable transition layer 2. The thickness of the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) is 5 nm, and the thickness of the copper layer is 60 nm. The magnetron sputtering process is as follows: Keep the temperature of the base film at -20 °C, the sputtering pressure at 0.5 Pa, the power at 10 KW, and deposit a 5-nm-thick AlMgLiZnCu layer on both sides of the base film at a speed of 4 m / min. Then, set the power of the copper target to 15 KW and deposit a 60-nm-thick copper layer on both sides of the base film at a speed of 4 m / min.

[0038] S2: Electroplate the copper layer on the surface of S1 to thicken the copper and form the metal layer 3 to obtain the functional current collector. The thickness of the electroplated thickened copper is 1 μm. The electroplating process is as follows: Place the film material with the sputtered copper layer in a water plating tank with an electroplating solution at a constant temperature of 22 °C. The electroplating solution composition is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive. The copper plating additive includes 20 mg / L of sodium polydithiopropane sulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0039] Example 7: Modify the thickness of the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) to 15 nm, and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1, and deposit the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) on the surface of the base film 1 by magnetron sputtering. Then, use copper as the target and magnetron sputter to deposit a copper layer on the surface of the heat-shrinkable transition layer 2. The thickness of the heat-shrinkable transition layer 2 (AlMgLiZnCu layer) is 15 nm, and the thickness of the copper layer is 60 nm. The magnetron sputtering process is as follows: Keep the temperature of the base film at -20 °C, the sputtering pressure at 0.5 Pa, the power at 10 KW, and deposit a 15-nm-thick AlMgLiZnCu layer on both sides of the base film at a speed of 4 m / min. Then, set the power of the copper target to 15 KW and deposit a 60-nm-thick copper layer on both sides of the base film at a speed of 4 m / min.

[0040] S2: Electroplate the copper layer on the surface of S1 to thicken the copper, forming the metal layer 3 to obtain the functional current collector; wherein the thickness of the electroplated thickened copper is 1 μm; the electroplating process is as follows: place the film material with the sputtered copper layer in the electroplating bath with a constant temperature of 22 °C, and the composition of the electroplating solution is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive; the copper plating additive includes 20 mg / L of sodium polydithiopropane sulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0041] Comparative Example 1: Remove the thermal shrinkage transition layer 2 (AlMgLiZnCu layer), and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1, and then use copper as the target to magnetron sputter and deposit a copper layer on its surface; the thickness of the copper layer is 60 nm; the magnetron sputtering process is as follows: keep the base film temperature at -20 °C, the sputtering pressure at 0.5 Pa, set the copper target power at 15 KW, and deposit a 60-nm-thick copper layer on the upper and lower surfaces of the base film at a speed of 4 m / min;

[0042] S2: Electroplate the copper layer on the surface of S1 to thicken the copper, forming the current collector; wherein the thickness of the electroplated thickened copper is 1 μm; the electroplating process is as follows: place the film material with the sputtered copper layer in the electroplating bath with a constant temperature of 22 °C, and the composition of the electroplating solution is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive; the copper plating additive includes 20 mg / L of sodium polydithiopropane sulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0043] Comparative Example 2: Replace the thermal shrinkage transition layer 2 (AlMgLiZnCu layer) with a Cr20Ni80 layer, and the rest is the same as in Example 1. The specific steps are as follows: S1: Use a 4.5-μm polypropylene film as the base film 1, use the magnetron sputtering process to deposit the thermal shrinkage transition layer 2 (Cr20Ni80 layer) on the surface of the base film 1, and then use copper as the target to magnetron sputter and deposit a copper layer on the surface of the thermal shrinkage transition layer 2; wherein the thickness of the thermal shrinkage transition layer 2 (Cr20Ni80 layer) is 10 nm, and the thickness of the copper layer is 60 nm; the magnetron sputtering process is as follows: keep the base film temperature at -20 °C, the sputtering pressure at 0.5 Pa, the power at 10 KW, and deposit a 10-nm-thick Cr20Ni80 layer on the upper and lower surfaces of the base film at a speed of 4 m / min; then set the copper target power at 15 KW, and deposit a 60-nm-thick copper layer on the upper and lower surfaces of the base film at a speed of 4 m / min;

[0044] S2: Electroplate the copper layer surface of S1 with thickened copper to form a metal layer 3, obtaining a functional current collector; wherein the thickness of the electroplated thickened copper is 1 μm; the electroplating process is as follows: Place the film material with the sputtered copper layer in a water plating tank with a constant temperature of 22 °C for the electroplating solution, where the electroplating solution composition is 100 g / L copper sulfate, 120 g / L sulfuric acid, 50 mg / L hydrochloric acid, and a copper plating additive; the copper plating additive includes 20 mg / L of sodium polydithiopropane sulfonate and 200 mg / L of polyethylene glycol, and the molecular weight of the polyethylene glycol is 8000.

[0045] Detection test:

[0046] Tensile strength test: Use the finished product prepared by the present invention as a specimen, and adopt an MTS Criterion42 type tensile testing machine to measure the tensile strength of the specimen. Parameter settings: The fixture spacing on the tensile testing machine is 100 mm, the test speed is 225 mm / min, and the tensile strength is obtained through testing.

[0047] Thermal shrinkage rate test: Use the finished product prepared by the present invention as a specimen, and adopt an RSY-01 thin film thermal shrinkage tester to measure the thermal shrinkage rate of the specimen. Parameter settings: Immerse the specimen quickly into the medium of a constant temperature bath at 142 °C and start timing. During the test process, keep the specimen evenly heated and freely shrink. After 20 s, take out the specimen and immerse it into the medium of a normal temperature bath for cooling. After cooling for 5 s, take it out and let it stand horizontally for 10 min, and the thermal shrinkage rate is obtained through testing. The results are as follows in the table:

[0048]

[0049] Conclusion: By adding a thermal shrinkage transition layer, the thermal shrinkage deformation amount of the functional current collector during cyclic application can be effectively reduced, the problems of large thermal deformation amount and large residual stress of the functional current collector can be solved, and thus the cycle life and safety performance of the battery can be improved; in addition, by adding a thermal shrinkage transition layer, the anti-deformation ability and mechanical strength of the functional current collector can be effectively enhanced, thereby enhancing the strength of the battery's service life.

[0050] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to this process, method, article or device.

[0051] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a functional current collector with low thermal shrinkage and high tensile strength, characterized in that: The following steps are involved: S1: taking a base film (1), using a magnetron sputtering process to plate a heat shrinkable transition layer (2) on the surface of the base film (1), and then using copper or a copper alloy as a target material to magnetron sputter plate a copper or a copper alloy layer on the surface of the heat shrinkable transition layer (2); S2: plating the copper or copper alloy layer of S1 with water to thicken the copper or copper alloy to form a metal layer (3) to obtain a functional current collector; The heat shrinkage rate of the heat shrinkage transition layer (2) is within the range between the metal layer (3) and the base film (1), and the heat shrinkage rate of the heat shrinkage transition layer (2) is less than the heat shrinkage rate of the base film (1); the material of the heat shrinkage transition layer (2) is a high entropy alloy, specifically TaNbHfZrTi, TaNbHfZrTiMo 0.75 , MoNbTaTiV, AlMgLiZnCu, AlMgZnCuSi, AlZrTiNbMo, CoCrFeMnNi, NbMoTaWVCr, ZrTiHfV 0.5 Nb 0.5 C 0.2 , TaNbHfZrTiMoW, VNbMoTaW, Ti 4.8 Zr2H 1.5 AlNb 0.7 , any one of Ti3Al2V2Nb2Mo.

2. The method for preparing a functional current collector with low thermal shrinkage and high tensile strength according to claim 1, characterized in that: The base film (1) is made of any one of polypropylene, polyethylene terephthalate, polyimide, polyethylene naphthalate, polyether sulfone, polyethylene, polyvinyl chloride, polystyrene, polycarbonate and polyvinylidene fluoride.

3. The method for preparing a functional current collector with low thermal shrinkage and high tensile strength according to claim 1, characterized in that: In step S1, the thickness of the base film (1) is 4.0-4.5 μm.

4. The method for preparing a functional current collector with low thermal shrinkage and high tensile strength according to claim 1, characterized in that: In step S1, the thickness of the heat shrinkable transition layer (2) is 5-15 nm.

5. The method for preparing a functional current collector with low thermal shrinkage and high tensile strength according to claim 1, characterized in that: In step S1, the thickness of the copper or copper alloy layer is 60-70 nm.

6. The method for preparing a functional current collector with low thermal shrinkage and high tensile strength according to claim 1, characterized in that: In step S2, the copper or copper alloy is thickened by water plating to a thickness of 1-2 μm.

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