A high-strength, corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure, its preparation method, and its application.

Abstract

This invention relates to a high-strength, corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure, its preparation method, and its application, belonging to the fields of copper foil materials and battery technology. The nickel-plated copper foil of this invention includes a copper foil substrate and plating layers disposed on both sides of the copper foil substrate; each side of the plating layer sequentially includes a first plating layer, a second plating layer, and a third plating layer; the first plating layer is a nickel-tungsten alloy layer with a nanocrystalline structure; the second plating layer is a nanocrystalline pure nickel layer with a (200) crystal plane preferred orientation; the third plating layer is a nickel-cobalt alloy layer with a (111) crystal plane preferred orientation; the first and second plating layers are deposited using pulse electroplating, and the third plating layer is deposited using direct current electroplating. This invention, through its multi-layer gradient structure design, significantly improves the tensile strength, interfacial bonding strength, and corrosion resistance of the copper foil, making it suitable for high-requirement applications such as solid-state batteries.

Description

Technical Field

[0001] This invention relates to the fields of copper foil materials and battery technology, and in particular to a high-strength, corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure, its preparation method, and its application. Background Technology

[0002] With the booming development of the new energy vehicle industry, the research and development of lithium-ion batteries with higher energy density, stronger safety performance, and longer cycle life has become the main direction of future development. Copper foil, as the negative electrode current collector, directly affects the battery's lifespan due to its mechanical properties and chemical stability. Especially in next-generation solid-state batteries, an electrochemical reaction occurs when copper foil comes into contact with a sulfide solid electrolyte, causing copper foil corrosion, leading to a decrease in current collector strength, and ultimately affecting the battery's cycle life.

[0003] To improve the overall performance of lithium-ion battery copper foil, the industry has proposed several technical approaches, such as plating nickel or nickel alloy layers on the copper foil surface. However, most existing plating layers have a simple structure, resulting in problems such as excessively large grain size, low adhesion, and insufficient corrosion resistance. Furthermore, a single plating layer cannot simultaneously meet the combined requirements of high strength and corrosion resistance of copper foil. In addition, insufficient adhesion between the copper foil substrate and the plating layer can easily lead to plating cracking, affecting the battery's long-term lifespan.

[0004] Therefore, developing a novel lithium-ion nickel-copper foil that combines a multi-layered coating structure, excellent interfacial bonding, high strength, and corrosion resistance is of great significance for improving the performance of next-generation solid-state batteries. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure, its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure, comprising a copper foil substrate and plating layers disposed on both sides of the copper foil substrate; the plating layer on each side sequentially comprises a first plating layer, a second plating layer and a third plating layer, wherein the first plating layer is disposed on the copper foil substrate; The first coating on each side is a nickel-tungsten (Ni-W) alloy layer, the second coating on each side is a nanocrystalline pure nickel (Ni) layer, and the third coating on each side is a nickel-cobalt (Ni-Co) alloy layer. The thickness of the first coating is 50~150 nm, and the grain size is no greater than 30 nm; the thickness of the second coating is 200~500 nm, and the grain size is no greater than 50 nm; the thickness of the third coating is 300~800 nm, and the grain size is no greater than 300 nm.

[0007] This invention uses a three-layer gradient plating structure—a nickel-tungsten (Ni-W) alloy layer, a nanocrystalline pure nickel (Ni) layer, and a nickel-cobalt (Ni-Co) alloy layer—as the nickel plating layer for copper foil, significantly improving the strength and corrosion resistance of the nickel-plated copper foil. By utilizing the high bonding strength and corrosion resistance of the nickel-tungsten alloy layer, the high strength of the nanocrystalline pure nickel layer, and the corrosion resistance of the nickel-cobalt alloy layer, the mechanical properties and chemical stability of the copper foil are simultaneously improved. The nickel-plated copper foil of this invention has a tensile strength ≥620 MPa, a tensile strength retention rate ≥88% after immersion in a sulfide electrolyte for 500 hours, and an interfacial adhesion force ≥1.0 N / mm.

[0008] The three-layer gradient structure of the present invention must meet a specific order: a nickel-tungsten alloy layer must be coated on the copper foil substrate as the first coating layer, a nanocrystalline pure nickel layer must be coated on the nickel-tungsten alloy layer as the intermediate layer, and a nickel-cobalt alloy layer must be coated on the nanocrystalline pure nickel layer as the surface layer.

[0009] In a preferred embodiment of the high-strength corrosion-resistant nickel-plated copper foil of the present invention, the thickness of the copper foil substrate layer is 3.5~10 μm.

[0010] In a preferred embodiment of the high-strength corrosion-resistant nickel-plated copper foil of the present invention, the copper foil substrate is an electrolytic copper foil or a rolled copper foil.

[0011] As a preferred embodiment of the high-strength corrosion-resistant nickel-plated copper foil of the present invention, the surface roughness (Rz) of the copper foil substrate layer is not greater than 2.0 μm.

[0012] As a preferred embodiment of the high-strength corrosion-resistant nickel-plated copper foil of the present invention, the first coating has a tungsten content of 5~15wt%, a grain size of 10~30 nm, and a nanocrystalline structure.

[0013] As a preferred embodiment of the high-strength corrosion-resistant nickel-plated copper foil of the present invention, the grain size of the second coating is 20~50 nm, has a preferred orientation of (200) crystal plane, and the texture coefficient (200) is not less than 60%.

[0014] As a preferred embodiment of the high-strength corrosion-resistant nickel-plated copper foil of the present invention, the third coating has a cobalt content of 10~20 wt%, a grain size of 100~300 nm, a (111) crystal plane preferred orientation, and a texture coefficient (111) of not less than 70%.

[0015] In a preferred embodiment of the high-strength corrosion-resistant nickel-plated copper foil of the present invention, the total thickness of the plating layer does not exceed 1.2 μm.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned high-strength corrosion-resistant nickel-plated copper foil, which includes the following steps: S1. Activate and clean the copper foil to obtain pretreated copper foil; S2. Deposit the first plating layer on both sides of the pretreated copper foil in step S1: Immerse the pretreated copper foil in the first nickel plating solution and perform pulse electroplating to form a nickel-tungsten alloy layer on the copper foil substrate. S3. Deposit a second plating layer on the first plating layer on both sides of step S2: Immerse the copper foil on which the first plating layer is deposited into the second nickel plating solution and perform pulse electroplating to form a nanocrystalline pure nickel layer on the first plating layer. S4. Deposit a third coating on the second coating on both sides of step S3: Immerse the copper foil on which the second coating is deposited into the third nickel plating solution and perform DC electroplating to form a nickel-cobalt alloy layer on the second coating. S5. The copper foil after the third plating layer is deposited in step S4 is subjected to anti-oxidation treatment, washed with water, dried with hot air, and wound up to obtain high-strength corrosion-resistant nickel-plated copper foil.

[0017] In a preferred embodiment of the preparation method described in this invention, in step S1, the activation and cleaning involve sequentially degreasing, acid-washing activation, and cleaning the copper foil.

[0018] In a preferred embodiment of the preparation method described in this invention, in step S1, the cleaning is performed using plasma or ultrasound to increase surface activity.

[0019] In a preferred embodiment of the preparation method described in this invention, in step S1, the plasma cleaning utilizes argon plasma with a processing power of 150-300 W and a processing time of 2-6 minutes. Using plasma for cleaning can further improve the adhesion of the nickel-plated copper foil.

[0020] In a preferred embodiment of the preparation method described in this invention, the pulse electroplating process conditions in step S2 are: current density 2~5 A / dm³. 2 The duty cycle is 20-40%, the frequency is 100-350 Hz, the temperature is 40-55℃, and the deposition time is 10-30 seconds.

[0021] In a preferred embodiment of the preparation method described in this invention, in step S2, the first nickel plating solution comprises: water, nickel sulfate 150~250 g / L, sodium tungstate 20~50 g / L, citric acid 50~100 g / L, sodium saccharin 0.5~1.5 g / L, and the pH value is adjusted to 5.0~6.5.

[0022] In a preferred embodiment of the preparation method described in this invention, the pulse electroplating process conditions in step S3 are: current density 4~8 A / dm³. 2 Duty cycle 15~35%, frequency 500~1500 Hz, temperature 45~60℃, deposition time 20~55 seconds.

[0023] In a preferred embodiment of the preparation method described in this invention, in step S3, the composition of the second nickel plating solution includes: water, nickel sulfate 250~350 g / L, nickel chloride 30~50 g / L, boric acid 30~40 g / L, sodium saccharin 0.5~2 g / L, and 1,4-butynediol 0.1~0.5 g / L, with a pH of 3.0~4.5.

[0024] In a preferred embodiment of the preparation method described in this invention, the DC electroplating process conditions in step S4 are: current density 6~12 A / dm³. 2 Temperature 55~65℃, deposition time 30~60 seconds.

[0025] In a preferred embodiment of the preparation method described in this invention, in step S4, the third nickel plating solution comprises: water, 200-300 g / L nickel sulfate, 20-55 g / L cobalt sulfate, 45-65 g / L nickel chloride, 30-45 g / L boric acid, and 0.05-0.15 g / L sodium dodecyl sulfate, with a pH of 4.0-6.0.

[0026] Thirdly, the present invention provides the application of the above-mentioned high-strength corrosion-resistant nickel-plated copper foil in the preparation of batteries, electromagnetic shielding materials or high-performance printed circuit boards.

[0027] In a preferred embodiment of the application described in this invention, the battery includes a solid-state battery or a lithium-ion battery.

[0028] Fourthly, the present invention provides a solid-state battery, wherein the negative electrode current collector of the solid-state battery comprises the aforementioned high-strength corrosion-resistant nickel-plated copper foil.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The nickel-plated copper foil of the present invention comprises a copper foil substrate and plating layers disposed on both sides of the copper foil substrate; the plating layers on each side sequentially include a first plating layer, a second plating layer, and a third plating layer; the first plating layer is a nickel-tungsten alloy layer with a thickness of 50~150 nm and a nanocrystalline structure; the second plating layer is a nanocrystalline pure nickel layer with a thickness of 200~500 nm and a (200) crystal plane preferred orientation; the third plating layer is a nickel-cobalt alloy layer with a thickness of 300~800 nm and a (111) crystal plane preferred orientation; its preparation method includes pretreatment, pulse electroplating deposition of the first and second plating layers, DC electroplating deposition of the third plating layer, and post-treatment. The present invention, through a multi-layer gradient structure design, significantly improves the tensile strength, interfacial bonding force, and corrosion resistance of the copper foil, making it suitable for high-requirement applications such as solid-state batteries. Attached Figure Description

[0030] Figure 1This is a schematic diagram of the structure of the nickel-plated copper foil of the present invention, wherein 1 represents the copper foil substrate layer, 2 represents the first plating layer, 3 represents the second plating layer, and 4 represents the third plating layer. Figure 2 The XRD pattern of the nickel-plated copper foil in Example 1 of this invention; Figure 3 This is a comparison diagram of the stress-strain curves of copper foil in Example 1 of the present invention with those of Comparative Examples 4 and 5. Detailed Implementation

[0031] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0032] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.

[0033] Example 1 An embodiment of the present invention provides a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The high-strength corrosion-resistant nickel-plated copper foil of this embodiment includes a copper foil substrate layer and plating layers disposed on both sides of the copper foil substrate layer. The plating layer on each side sequentially includes a first plating layer, a second plating layer and a third plating layer, wherein the first plating layer is disposed on the copper foil substrate layer. The thickness of the copper foil substrate is 6 μm; The first coating on each side is a nickel-tungsten alloy layer, the second coating on each side is a nanocrystalline pure nickel layer, and the third coating on each side is a nickel-cobalt alloy layer.

[0034] The preparation method of high-strength corrosion-resistant nickel-plated copper foil in this embodiment includes the following steps: (1) Select an electrolytic copper foil with a thickness of 6 μm, and successively degrease it with acetone, activate it with 10% dilute sulfuric acid for 30 seconds, rinse it with deionized water, and then perform argon plasma cleaning (power 200 W, 2 minutes) to obtain pretreated copper foil; (2) Deposit the first plating layer on both sides of the pretreated copper foil in step (1): Immerse the pretreated copper foil in the first nickel plating solution (nickel sulfate 200 g / L, sodium tungstate 30 g / L, citric acid 80 g / L, sodium saccharin 1 g / L, pH adjusted to 5.5 with ammonia, temperature 45℃), and use pulse electroplating with a current density of 3 A / dm³. 2 With a duty cycle of 30%, a frequency of 200 Hz, and a deposition time of 20 seconds, a nickel-tungsten alloy layer with a thickness of about 80 nm (tungsten content of 9.5 wt.%) was formed on both sides, with a grain size of about 18 nm. (3) Deposit a second coating on the first coating on both sides of step (2): Immerse the copper foil on which the first coating is deposited into the second nickel plating solution (nickel sulfate 300 g / L, nickel chloride 40 g / L, boric acid 35 g / L, sodium saccharin 1.5 g / L, 1,4-butynediol 0.3 g / L, pH 4.0, temperature 50℃), and use pulse electroplating with a current density of 7 A / dm 2 With a duty cycle of 20%, a frequency of 1000 Hz, and a deposition time of 50 seconds, a nanocrystalline pure nickel layer with a thickness of about 300 nm was formed on both sides, with a grain size of about 35 nm. After XRD testing, it showed a (200) crystal plane preferred orientation. (4) Deposit a third coating on the second coating on both sides of step (3): Immerse the copper foil on which the second coating is deposited into the third nickel plating solution (nickel sulfate 250 g / L, cobalt sulfate 40 g / L, nickel chloride 50 g / L, boric acid 40 g / L, sodium dodecyl sulfate 0.1 g / L, pH 4.5, temperature 60℃), and use direct current electroplating with a current density of 8 A / dm³. 2 The deposition time was 45 seconds, and a nickel-cobalt alloy layer with a thickness of about 550 nm (cobalt content 14.5 wt.%) was formed on both sides, with a grain size of about 180 nm. (5) Immerse the copper foil after the third coating is deposited in step (4) in 0.5% benzotriazole anti-oxidation solution for 30 seconds, wash with water, dry with hot air, and roll up to obtain high-strength corrosion-resistant nickel-plated copper foil.

[0035] In the nickel-plated copper foil of the present invention, the thickness of the first plating layer is 80 nm, the thickness of the second plating layer is 300 nm, and the thickness of the third plating layer is 550 nm.

[0036] A schematic diagram of the structure of the nickel-plated copper foil of the present invention is shown below. Figure 1 As shown, 1 represents the copper foil substrate, 2 represents the first plating layer, 3 represents the second plating layer, and 4 represents the third plating layer.

[0037] Example 2-3 This invention discloses two embodiments of a high-strength, corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. Embodiments 2-3 have the same structure and preparation method as Embodiment 1, differing only in the thickness of the copper foil substrate layer. Specifically, Example 2: Compared with Example 1, the thickness of the copper foil substrate layer in Example 1 was adjusted from 6 μm to 3.5 μm; Example 3: Compared with Example 1, the thickness of the copper foil substrate layer in Example 1 was adjusted from 6 μm to 8 μm.

[0038] In Example 2, the thickness of the first coating layer in the high-strength corrosion-resistant nickel-plated copper foil is 82 nm, the thickness of the second coating layer is 307 nm, and the thickness of the third coating layer is 552 nm.

[0039] In Example 3, the thickness of the first coating layer in the high-strength corrosion-resistant nickel-plated copper foil is 81 nm, the thickness of the second coating layer is 304 nm, and the thickness of the third coating layer is 553 nm.

[0040] Example 4 This invention provides an embodiment of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The difference between this embodiment and Embodiment 1 is only in the pretreatment method of the copper foil. Compared with Embodiment 1, this embodiment replaces the argon plasma cleaning for 2 minutes in step (1) of the preparation method in Embodiment 1 with conventional water washing for 2 minutes.

[0041] Example 5 This invention discloses an embodiment of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The difference between this embodiment and Embodiment 1 lies only in the thickness, tungsten content, cobalt content, and grain size of each layer. The high-strength corrosion-resistant nickel-plated copper foil of this embodiment includes a copper foil substrate layer and plating layers disposed on both sides of the copper foil substrate layer. The plating layer on each side sequentially includes a first plating layer, a second plating layer, and a third plating layer, wherein the first plating layer is disposed on the copper foil substrate layer. The thickness of the copper foil substrate is 6 μm; the first coating on each side is a nickel-tungsten alloy layer, the second coating on each side is a nanocrystalline pure nickel layer, and the third coating on each side is a nickel-cobalt alloy layer.

[0042] The preparation method of high-strength corrosion-resistant nickel-plated copper foil in this embodiment includes the following steps: (1) Same as step (1) in embodiment 1; (2) Deposit the first coating on both sides of the pretreated copper foil in step (1): Immerse the pretreated copper foil in the first nickel plating solution (the composition of the first nickel plating solution is adjusted to: nickel sulfate 180 g / L, sodium tungstate 20 g / L, citric acid 60 g / L, sodium saccharin 0.8 g / L, pH adjusted to 5.5 with ammonia, temperature 45℃); use pulse electroplating, current density 2.5 A / dm 2 With a duty cycle of 30%, a frequency of 200 Hz, and a deposition time of 12 seconds, a nickel-tungsten alloy layer with a thickness of about 50 nm, a tungsten content of about 5 wt%, and a grain size of about 10 nm was formed on both sides. (3) Deposit a second coating on the first coating on both sides of step (2): Immerse the copper foil on which the first coating is deposited into the second nickel plating solution (composition is the same as in Example 1: 300 g / L nickel sulfate, 40 g / L nickel chloride, 35 g / L boric acid, 1.5 g / L sodium saccharin, 0.3 g / L 1,4-butynediol, pH 4.0, temperature 50℃); use pulse electroplating with a current density of 6 A / dm 2With a duty cycle of 20%, a frequency of 1000 Hz, and a deposition time of 33 seconds, nanocrystalline pure nickel layers with a thickness of about 200 nm and a grain size of about 20 nm were formed on both sides. XRD tests showed that the (200) crystal plane was preferentially oriented. (4) Deposit a third coating on the second coating on both sides of step (3): Immerse the copper foil with the second coating into the third nickel plating solution (the composition of the third nickel plating solution is adjusted to: nickel sulfate 220 g / L, cobalt sulfate 20 g / L, nickel chloride 45 g / L, boric acid 35 g / L, sodium dodecyl sulfate 0.08 g / L, pH 4.5, temperature 60℃); use DC electroplating with a current density of 7 A / dm 2 The deposition time was 25 seconds, and a nickel-cobalt alloy layer with a thickness of about 300 nm, a cobalt content of about 10 wt%, and a grain size of about 100 nm was formed on both sides. (5) Same as step (5) in Example 1, to obtain high-strength corrosion-resistant nickel-plated copper foil.

[0043] In this embodiment, the first coating layer of the high-strength corrosion-resistant nickel-plated copper foil is a nickel-tungsten alloy layer with a thickness of 50 nm, a tungsten content of 5 wt%, and a grain size of 10 nm; the second coating layer is a nanocrystalline pure nickel layer with a thickness of 200 nm, a grain size of 20 nm, and XRD testing shows that it has a (200) crystal plane preferred orientation; the third coating layer is a nickel-cobalt alloy layer with a thickness of 300 nm, a cobalt content of 10 wt%, and a grain size of 100 nm.

[0044] Example 6 This invention discloses an embodiment of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The difference between this embodiment and Embodiment 1 lies only in the thickness, tungsten content, cobalt content, and grain size of each layer. The high-strength corrosion-resistant nickel-plated copper foil of this embodiment includes a copper foil substrate layer and plating layers disposed on both sides of the copper foil substrate layer. The plating layer on each side sequentially includes a first plating layer, a second plating layer, and a third plating layer, wherein the first plating layer is disposed on the copper foil substrate layer. The thickness of the copper foil substrate is 6 μm; the first coating on each side is a nickel-tungsten alloy layer, the second coating on each side is a nanocrystalline pure nickel layer, and the third coating on each side is a nickel-cobalt alloy layer.

[0045] The preparation method of high-strength corrosion-resistant nickel-plated copper foil in this embodiment includes the following steps: (1) Same as step (1) in Example 1; (2) Deposit the first coating on both sides of the pretreated copper foil in step (1): Immerse the pretreated copper foil in the first nickel plating solution (the composition of the first nickel plating solution is adjusted to: nickel sulfate 220 g / L, sodium tungstate 50 g / L, citric acid 90 g / L, sodium saccharin 1.2 g / L, pH adjusted to 5.5 with ammonia water, temperature 45℃); use pulse electroplating, current density 4 A / dm2 With a duty cycle of 30%, a frequency of 200 Hz, and a deposition time of 28 seconds, a nickel-tungsten alloy layer with a thickness of about 150 nm, a tungsten content of about 15 wt%, and a grain size of about 30 nm was formed on both sides. (3) Deposit a second plating layer on both sides of the first plating layer in step (2): Immerse the copper foil on which the first plating layer is deposited into the second nickel plating solution (the composition is the same as in Example 1); use pulse electroplating with a current density of 8 A / dm 2 With a duty cycle of 20%, a frequency of 1000Hz, and a deposition time of 72 seconds, nanocrystalline pure nickel layers with a thickness of about 500 nm and a grain size of about 50 nm were formed on both sides. XRD tests showed that the (200) crystal plane had a preferred orientation. (4) Deposit a third coating on the second coating on both sides of step (3): Immerse the copper foil on which the second coating is deposited into the third nickel plating solution (the composition of the third nickel plating solution is adjusted to: nickel sulfate 280 g / L, cobalt sulfate 55 g / L, nickel chloride 60 g / L, boric acid 45 g / L, sodium dodecyl sulfate 0.12 g / L, pH 4.5, temperature 60℃); use DC electroplating with a current density of 11 A / dm 2 The deposition time was 65 seconds, and a nickel-cobalt alloy layer with a thickness of about 800 nm, a cobalt content of about 20 wt%, and a grain size of about 300 nm was formed on both sides. (5) Same as step (5) in Example 1.

[0046] In this embodiment, the first coating layer of the high-strength corrosion-resistant nickel-plated copper foil is a nickel-tungsten alloy layer with a thickness of 150 nm, a tungsten content of 15 wt%, and a grain size of 30 nm; the second coating layer is a nanocrystalline pure nickel layer with a thickness of 500 nm and a grain size of 50 nm, which, after XRD testing, has a (200) crystal plane preferred orientation; the third coating layer is a nickel-cobalt alloy layer with a thickness of 800 nm, a cobalt content of 20 wt%, and a grain size of 300 nm.

[0047] Comparative Example 1 This invention provides a comparative example of a high-strength, corrosion-resistant nickel-plated copper foil with a multi-layered gradient structure and its preparation method. The difference between this comparative example and Example 1 lies only in the thickness of each layer. Specifically, In this comparative example of nickel-plated copper foil, the thickness of the first plating layer on each side is 40 nm (the deposition time in step (2) of the corresponding preparation method is adjusted to 10 seconds). The thickness of the second coating on each side is 360 nm (the deposition time in step (3) of the corresponding preparation method is adjusted to 60 seconds). The thickness of the third coating on each face is 305 nm (the deposition time in step (4) of the corresponding preparation method is adjusted to 25 seconds).

[0048] Comparative Example 2 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The structure of this comparative example is the same as that of the high-strength corrosion-resistant nickel-plated copper foil in Example 1, except that the grain size of the second plating layer is different. Compared with Example 1, the grain size of the second plating layer in Example 1 is adjusted from 35 nm to 65 nm (corresponding to the content of saccharin sodium in the second nickel plating solution in step (3) of the preparation method in Example 1 being adjusted to 0.2 g / L and 1,4-butynediol being adjusted to 0.05 g / L).

[0049] Comparative Example 3 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The only difference between this comparative example and Example 1 is the grain size of the third plating layer. Compared with Example 1, the grain size of the third plating layer in Example 1, which was 180 nm, is adjusted to 350 nm (corresponding to the temperature of the third nickel plating solution in step (4) of the preparation method in Example 1 being adjusted to 70°C).

[0050] Comparative Example 4 This invention provides a comparative example of a high-strength, corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. This comparative example is a commercially available 6 μm electrolytic copper foil without plating.

[0051] Comparative Example 5 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a single-layer nickel-plated copper foil with a nanocrystalline pure nickel layer. A nanocrystalline pure nickel layer is deposited on one side of a 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to the second plating solution in step (3) of the preparation method of Example 1, a nanocrystalline pure nickel layer of about 500 nm is deposited on one side of the pretreated copper foil by DC electroplating.

[0052] Comparative Example 6 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a single-layer nickel-tungsten alloy layer nickel-plated copper foil. A nickel-tungsten alloy layer is plated on one side of a 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, a nickel-tungsten alloy layer of about 80 nm is plated on one side of the pretreated copper foil according to step (2) of the preparation method of Example 1.

[0053] Comparative Example 7 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a double-layer nickel-plated copper foil (compared to Example 1, the plating layer has no intermediate nanocrystalline pure nickel layer). The plating layer on each side is a nickel-tungsten alloy layer and a nickel-cobalt alloy layer in sequence. The nickel-tungsten alloy layer and the nickel-cobalt alloy layer are deposited sequentially on each side of the 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to step (2) of the preparation method of Example 1, a nickel-tungsten alloy layer of about 80 nm is plated on both sides of the pretreated copper foil. Then, according to step (4) of the preparation method of Example 1, a nickel-cobalt alloy layer of about 550 nm is plated on both sides of the nickel-tungsten alloy layer.

[0054] Comparative Example 8 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a double-layer nickel-plated copper foil (compared to Example 1, the plating layer does not have a bottom nickel-tungsten alloy layer). The plating layer on each side is a nanocrystalline pure nickel layer and a nickel-cobalt alloy layer in sequence. The nanocrystalline pure nickel layer and the nickel-cobalt alloy layer are deposited sequentially on each side of the 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to step (3) of the preparation method of Example 1, a nanocrystalline pure nickel layer of about 300 nm is plated on both sides of the pretreated copper foil. Then, according to step (4) of the preparation method of Example 1, a nickel-cobalt alloy layer of about 550 nm is plated on both sides of the nanocrystalline pure nickel layer.

[0055] Comparative Example 9 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a double-layer nickel-plated copper foil (compared to Example 1, the coating has no surface nickel-cobalt alloy layer). The coating on each side is successively a nickel-tungsten alloy layer and a nanocrystalline pure nickel layer. The nickel-tungsten alloy layer and the nanocrystalline pure nickel layer are sequentially deposited on each side of the 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to step (2) of the preparation method of Example 1, a nickel-tungsten alloy layer of about 80 nm is plated on both sides of the pretreated copper foil. Then, according to step (3) of the preparation method of Example 1, a nanocrystalline pure nickel layer of about 300 nm is plated on both sides of the nickel-tungsten alloy layer.

[0056] Comparative Example 10 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a double-layer nickel-plated copper foil (the plating order is different compared with Comparative Example 9). The plating on each side is a nanocrystalline pure nickel layer and a nickel-tungsten alloy layer in sequence. The nanocrystalline pure nickel layer and the nickel-tungsten alloy layer are deposited sequentially on each side of the 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to step (3) of the preparation method of Example 1, a nanocrystalline pure nickel layer of about 300 nm is plated on both sides of the pretreated copper foil. Then, according to step (2) of the preparation method of Example 1, a nickel-tungsten alloy layer of about 80 nm is plated on both sides of the nanocrystalline pure nickel layer.

[0057] Comparative Example 11 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a double-layer nickel-plated copper foil (the plating order is different compared with Comparative Example 7). The plating on each side is a nickel-cobalt alloy layer and a nickel-tungsten alloy layer in sequence. The nickel-cobalt alloy layer and the nickel-tungsten alloy layer are deposited sequentially on each side of the 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to step (4) of the preparation method of Example 1, a nickel-cobalt alloy layer of about 550 nm is plated on both sides of the pretreated copper foil. According to step (2) of the preparation method of Example 1, a nickel-tungsten alloy layer of about 80 nm is plated on both sides of the nickel-cobalt alloy layer.

[0058] Comparative Example 12 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a double-layer nickel-plated copper foil (the plating order is different compared with Comparative Example 8). The plating on each side is a nickel-cobalt alloy layer and a nanocrystalline pure nickel layer in sequence. The nickel-cobalt alloy layer and the nanocrystalline pure nickel layer are deposited sequentially on each side of the 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to step (4) of the preparation method of Example 1, a nickel-cobalt alloy layer of about 550 nm is plated on both sides of the pretreated copper foil. Then, according to step (3) of the preparation method of Example 1, a nanocrystalline pure nickel layer of about 300 nm is plated on both sides of the nickel-cobalt alloy layer.

[0059] Comparative Example 13 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The nickel-plated copper foil in this comparative example is a three-layer nickel-plated copper foil (the plating order is different compared with Example 1). The plating on each side is, in sequence, a nickel-cobalt alloy layer, a nanocrystalline pure nickel layer, and a nickel-tungsten alloy layer. The nickel-cobalt alloy layer, the nanocrystalline pure nickel layer, and the nickel-tungsten alloy layer are deposited sequentially on each side of the 6 μm copper foil. The 6 μm electrolytic copper foil is pretreated according to the pretreatment method of Example 1. Then, according to step (4) of the preparation method of Example 1, a nickel-cobalt alloy layer of about 550 nm is plated on both sides of the pretreated copper foil. Then, according to step (3) of the preparation method of Example 1, a nanocrystalline pure nickel layer of about 300 nm is plated on both sides of the nickel-cobalt alloy layer. Finally, according to step (2) of the preparation method of Example 1, a nickel-tungsten alloy layer of about 80 nm is plated on both sides of the nanocrystalline pure nickel layer.

[0060] Comparative Example 14 This invention provides a comparative example of a high-strength corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure and its preparation method. The copper-nickel alloy foil prepared in this comparative example is prepared according to the method of Example 1 in Patent 202010240309.3. The thickness of the obtained copper-nickel alloy foil is 6 μm and the nickel content is 7.2%.

[0061] Test Example 1 The grain size and texture factor (TC) of the copper foil coatings in the examples and comparative examples were tested.

[0062] Characterization was performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

[0063] XRD results show that in the nickel-plated copper foil of Example 1, the second coating has a (200) plane preferred orientation, and the third coating has a (111) crystal plane preferred orientation. The XRD pattern of the nickel-plated copper foil of Example 1 is shown below. Figure 2 As shown.

[0064] The copper foil structural parameters of Examples 1-6 and Comparative Examples 1-14 are shown in Tables 1-1 and 1-2, respectively. Table 1-1 Table 1-2 Test Example 2 Example and comparative copper foil performance testing: 1. Tensile strength The test was conducted using a universal testing machine with a gauge length of 50 mm and a tensile speed of 50 mm / min.

[0065] 2. Cohesion The adhesion strength was evaluated using the cross-cut adhesion test (ASTM D3359), with a grade of 0-5B; supplemented by a peel strength test (peel width 10 mm, peel speed 50 mm / min).

[0066] 3. Corrosion resistant The sample was placed in an electrolyte containing 0.01 mol / L Na2S and immersed at 60°C for 500 hours. The tensile strength before and after the treatment was tested, and the retention rate was calculated.

[0067] The performance test results of the copper foils of Examples 1-6 and Comparative Examples 1-14 are shown in Table 2. The stress-strain curves of the copper foils of Example 1, Comparative Examples 4 and 5 are compared in the figure below. Figure 3 As shown, Table 2 Table 2 shows that the nickel-plated copper foil corresponding to the three-layer gradient structure of the present invention has better performance. The tensile strength (702 MPa), corrosion retention rate (92.7%), and peel strength (1.12 N / mm) of the nickel-plated copper foil of Example 1 (Ni-W / nanocrystalline Ni / Ni-Co) are significantly better than those of no plating (Comparative Example 4), single-layer pure nickel (Comparative Example 5), and single-layer Ni-W (Comparative Example 6), indicating that the three-layer structure synergistically improves mechanical properties and corrosion resistance.

[0068] In the three-layer gradient structure of the coating, the Ni-W layer provides high adhesion and barrier effect. In Comparative Example 8, which lacks the Ni-W layer, the adhesion (0.68 N / mm) and retention rate (81.9%) of the nickel-plated copper foil are significantly reduced. The nanocrystalline Ni layer contributes to grain refinement and strengthening. In Comparative Example 7, which lacks the nanocrystalline Ni layer, the strength (548 MPa) and retention rate (78.0%) of the nickel-plated copper foil are reduced. The Ni-Co layer provides a key anti-corrosion barrier. In Comparative Example 9, which lacks the Ni-Co layer, the retention rate of the nickel-plated copper foil drops to 79.0%.

[0069] Using copper foil as a substrate, the three-layer gradient structure of the plating consists of a Ni-W layer, a nanocrystalline Ni layer, and a Ni-Co layer, in that order. The order of these three layers cannot be substituted. In Comparative Example 13, the plating order is reversed to Ni-Co / Ni / Ni-W. The strength (532 MPa), adhesion (0.45 N / mm), and retention rate (72.0%) of the nickel-plated copper foil are all inferior to those of Example 1, indicating that the plating of the present invention must follow the gradient order of "Ni-W / nanocrystalline Ni / Ni-Co".

[0070] In the preparation method of nickel-plated copper foil, plasma cleaning of the copper foil substrate (Example 4) can further improve the adhesion of the nickel-plated copper foil.

[0071] In the preparation method of nickel-plated copper foil, the thickness of each layer in the coating needs to meet specific conditions: the thickness of the first coating is 50-150 nm, the thickness of the second coating is 200-500 nm, and the thickness of the third coating is 300-800 nm. If the thickness exceeds the range, the mechanical properties and corrosion resistance of the nickel-plated copper foil will be significantly reduced.

[0072] Meanwhile, the grain size in the coating needs to meet specific conditions. The grain size of the second coating is 20-50 nm. If it exceeds the range (Comparative Example 2, 65 nm), the grains will coarsen, which will lead to a decrease in the strength of the nickel-plated copper foil (down to 547 MPa). The grain size of the third coating is 100-300 nm. If it exceeds the range (Comparative Example 3, 350 nm), the grains will be too large, which will lead to a decrease in the strength (572 MPa) and retention rate (82.5%) of the nickel-plated copper foil.

[0073] The nickel-plated copper foil of this invention exhibits significantly higher strength and retention rate than nickel-plated copper foil prepared by existing technologies, demonstrating that the nickel-plated copper foil of this invention has significant performance advantages.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-strength, corrosion-resistant nickel-plated copper foil with a multi-layer gradient structure, characterized in that, It includes a copper foil substrate and plating layers disposed on both sides of the copper foil substrate; the plating layers on each side sequentially include a first plating layer, a second plating layer and a third plating layer, wherein the first plating layer is disposed on the copper foil substrate; The first coating on each side is a nickel-tungsten alloy layer, the second coating on each side is a nanocrystalline pure nickel layer, and the third coating on each side is a nickel-cobalt alloy layer. The thickness of the first coating is 50~150 nm, and the grain size is no greater than 30 nm; the thickness of the second coating is 200~500 nm, and the grain size is no greater than 50 nm; the thickness of the third coating is 300~800 nm, and the grain size is no greater than 300 nm.

2. The high-strength, corrosion-resistant nickel-plated copper foil as described in claim 1, characterized in that, The thickness of the copper foil substrate is 3.5~10 μm; And / or, the copper foil substrate is electrolytic copper foil or rolled copper foil; And / or, the surface roughness of the copper foil substrate layer is not greater than 2.0 μm.

3. The high-strength, corrosion-resistant nickel-plated copper foil as described in claim 1, characterized in that, The first coating has a tungsten content of 5-15 wt% and a grain size of 10-30 nm, exhibiting a nanocrystalline structure. And / or, the grain size of the second coating is 20~50 nm, has a preferred orientation of (200) crystal planes, and the texture factor (200) is not less than 60%; And / or, the third coating has a cobalt content of 10~20 wt%, a grain size of 100~300 nm, a (111) preferred orientation, and a texture factor (111) of not less than 70%; And / or, the total thickness of the coating does not exceed 1.2 μm.

4. The method for preparing the high-strength corrosion-resistant nickel-plated copper foil according to any one of claims 1 to 3, characterized in that, It includes the following steps: S1. Activate and clean the copper foil to obtain pretreated copper foil; S2. Deposit the first plating layer on both sides of the pretreated copper foil in step S1: Immerse the pretreated copper foil in the first nickel plating solution and perform pulse electroplating to form a nickel-tungsten alloy layer on the copper foil substrate. S3. Deposit a second plating layer on the first plating layer on both sides of step S2: Immerse the copper foil on which the first plating layer is deposited into the second nickel plating solution and perform pulse electroplating to form a nanocrystalline pure nickel layer on the first plating layer. S4. Deposit a third coating on the second coating on both sides of step S3: Immerse the copper foil on which the second coating is deposited into the third nickel plating solution and perform DC electroplating to form a nickel-cobalt alloy layer on the second coating. S5. The copper foil after the third plating layer is deposited in step S4 is subjected to anti-oxidation treatment, washed with water, dried with hot air, and wound up to obtain high-strength corrosion-resistant nickel-plated copper foil.

5. The preparation method according to claim 4, characterized in that, In step S1, the activation and cleaning involve sequentially degreasing, acid-washing activation, and cleaning the copper foil.

6. The preparation method according to claim 5, characterized in that, In step S1, the cleaning is performed using plasma or ultrasound.

7. The preparation method according to claim 4, characterized in that, In step S2, the pulse electroplating process conditions are: current density 2~5 A / dm³. 2 Duty cycle 20~40%, frequency 100~350 Hz, temperature 40~55℃, deposition time 10~30 seconds; And / or, in step S3, the pulse electroplating process conditions are: current density 4~8 A / dm³. 2 Duty cycle 15~35%, frequency 500~1500 Hz, temperature 45~60℃, deposition time 20~55 seconds; And / or, in step S4, the process conditions for DC electroplating are: current density 6~12 A / dm³. 2 Temperature 55~65℃, deposition time 30~60 seconds.

8. The preparation method according to claim 4, characterized in that, In step S2, the first nickel plating solution comprises: water, nickel sulfate 150~250 g / L, sodium tungstate 20~50 g / L, citric acid 50~100 g / L, sodium saccharin 0.5~1.5 g / L, and the pH value is adjusted to 5.0~6.5; And / or, in step S3, the composition of the second nickel plating solution includes: water, nickel sulfate 250~350 g / L, nickel chloride 30~50 g / L, boric acid 30~40 g / L, sodium saccharin 0.5~2 g / L and 1,4-butynediol 0.1~0.5 g / L, pH 3.0~4.5; And / or, in step S4, the composition of the third nickel plating solution includes: water, nickel sulfate 200~300 g / L, cobalt sulfate 20~55 g / L, nickel chloride 45~65 g / L, boric acid 30~45 g / L and sodium dodecyl sulfate 0.05~0.15 g / L, pH 4.0~6.

0.

9. The application of the high-strength corrosion-resistant nickel-plated copper foil according to any one of claims 1 to 3 in the preparation of batteries, electromagnetic shielding materials or high-performance printed circuit boards.

10. A solid-state battery, characterized in that, The negative electrode current collector of the solid-state battery includes the high-strength corrosion-resistant nickel-plated copper foil as described in any one of claims 1 to 3.

Images