A chromium-free copper antioxidant for battery negative electrode current collector, and its preparation method and application

Abstract

The present invention relates to a chromium-free copper antioxidant for battery negative electrode collector plates, its preparation method, and application. The chromium-free copper antioxidant for battery negative electrode collector plates of the present invention comprises antioxidant A and antioxidant B. Antioxidant A comprises a primary corrosion inhibitor and a dilute alcohol solution, and antioxidant B is a secondary corrosion inhibitor. The primary corrosion inhibitor comprises tannic acid and / or sulfosalicylic acid, and also comprises sodium molybdate and / or sodium hexametaphosphate. The secondary corrosion inhibitor is selected from one or more of thiourea, EDTA·2Na, and polyaspartic acid. The technology of the present invention can specifically protect the copper surface, forming a dense chemical conversion film within minutes, isolating the copper surface from air and preventing air oxidation. It can keep the battery negative electrode collector plate free of corrosion bubbles for 30 to 60 seconds under 40% concentrated nitric acid, and has good wettability and solderability. At the same time, the antioxidant of the present invention does not contain chromium, is green and environmentally friendly, and can be widely used in the new energy industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery materials, and in particular relates to a chromium-free copper antioxidant for a battery negative electrode current collector, and a preparation method and application thereof. Background Art

[0002] In lithium-ion battery structures, the negative electrode current collector plays a crucial role. Typically made of copper, it not only carries the active material but also serves as a collector and conduction medium for electrons, directly impacting the battery's overall performance and lifespan. Surface treatment of the negative electrode current collector, particularly passivation, is a key step in improving battery performance. The passivation layer effectively inhibits corrosion reactions on the metal surface and reduces the occurrence of side reactions, thereby improving battery safety and cycle life.

[0003] An important performance indicator of the negative electrode current collector is wettability and weldability. Improving the wettability of the negative electrode current collector can make the negative electrode active material (such as graphite, silicon-based materials, etc.) more evenly and tightly coated on the surface of the current collector, reducing the possibility of gaps and shedding, thereby improving the utilization rate of the active material and increasing the energy density of the battery. Weldability is a key indicator when the current collector is welded to the tab or other components during the assembly process. Poor weldability can lead to poor welding, such as cold welding and fracture, which seriously affect the mechanical stability and electrical contact reliability of the battery, thereby reducing the battery's yield and safety of use. However, there are few reports on the current passivation treatment technology for the negative electrode current collector specifically for optimizing solutions to improve wettability and weldability. Patent application CN116103643A discloses a chromium-free passivator for copper foil used in lithium batteries and its application. The passivator comprises a main salt, an organic acid, a corrosion inhibitor, a chelating agent, a complexing agent, an additive and an organic solvent. In addition, it also comprises an inositol substance. Under the synergistic effect of cyclohexane hexaphosphate, glucose and inositol (1,4,5) triphosphate, the salt spray resistance and oxidation resistance of 6-10μm double-glazed copper foil are greatly improved. However, the wettability and solderability of the copper foil are not improved. Patent application CN116555743A discloses a chromium-free passivator and its application. The passivator uses 5-35 parts of film-forming agent, 1-20 parts of inorganic salt, 1-8 parts of complexing agent, 0.1-5 parts of additive, 0.5-8 parts of corrosion inhibitor, 0.5-10 parts of oxidant, 1-15 parts of surfactant, and the balance is water. The passivator can improve the oxidation resistance, corrosion resistance and high temperature resistance of the copper foil passivation film, but the wettability and solderability of the copper foil have not been modified or studied.

[0004] In view of this, the development of a chromium-free copper antioxidant for battery negative electrode current collectors that can simultaneously effectively form a protective layer to enhance corrosion resistance and significantly improve the wettability and weldability of the current collector surface will improve the performance and extend the life of lithium-ion batteries, and has broad application prospects in the new energy industry. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a chromium-free copper antioxidant for a battery negative electrode current collector disc, and a preparation method and application thereof. The chromium-free copper antioxidant for a battery negative electrode current collector disc of the present invention can specifically protect the copper surface to prevent the copper surface from being oxidized by air, and has excellent corrosion resistance, wettability and weldability. At the same time, the antioxidant of the present invention does not contain chromium, is green and environmentally friendly, and can be widely used in the new energy industry.

[0006] In a first aspect, the present invention provides a chromium-free copper antioxidant for a battery negative electrode current collecting disc, wherein the chromium-free copper antioxidant for a battery negative electrode current collecting disc comprises an antioxidant A and an antioxidant B; the antioxidant A comprises a main corrosion inhibitor and a dilute alcohol solution, and the antioxidant B is a secondary corrosion inhibitor.

[0007] Furthermore, the main corrosion inhibitor contains tannic acid and / or sodium molybdate, and also contains one or more of sodium hexametaphosphate and / or sulfosalicylic acid.

[0008] Furthermore, the secondary corrosion inhibitor includes one or more of thiourea, EDTA·2Na, and polyaspartic acid.

[0009] Furthermore, the diluted alcohol includes alcohols and water, and the mass ratio of the alcohols to water is (10-30):100;

[0010] Furthermore, the alcohol is selected from one or more of ethanol, methanol, 1,2-propylene glycol, n-propanol and ethylene glycol.

[0011] Furthermore, the volume ratio of the antioxidant A to the antioxidant B is (5-8):(2-5).

[0012] Furthermore, the mass volume ratio of the main corrosion inhibitor to the dilute alcohol solution is 10-45g:1L.

[0013] Furthermore, when the main corrosion inhibitor also includes tannic acid, the mass volume ratio of tannic acid to the dilute alcohol solution is 5 to 15 g / L; when the main corrosion inhibitor also includes sodium molybdate, the mass volume ratio of sodium molybdate to the dilute alcohol solution is 5 to 20 g / L; when the main corrosion inhibitor also includes sodium hexametaphosphate, the mass volume ratio of sodium hexametaphosphate to the dilute alcohol solution is 10 to 20 g / L; when the corrosion inhibitor also includes sulfosalicylic acid, the mass volume ratio of sulfosalicylic acid to the dilute alcohol solution is 1 to 5 g / L.

[0014] Furthermore, the mass volume ratio of the secondary corrosion inhibitor to water in the antioxidant B is 0.05-15g:1L.

[0015] Furthermore, when the secondary corrosion inhibitor contains thiourea, the mass volume ratio of thiourea to pure water is 0.05 to 0.1 g / L; when the secondary corrosion inhibitor contains EDTA·2Na, the mass volume ratio of EDTA·2Na to pure water is 1 to 5 g / L; when the secondary corrosion inhibitor contains polyaspartic acid, the mass volume ratio of polyaspartic acid to pure water is 2 to 10 g / L.

[0016] In a second aspect, the present invention provides a method for preparing a chromium-free copper antioxidant for a negative electrode current collector of a battery, which specifically comprises the following steps:

[0017] S1. Dissolving the main corrosion inhibitor in a dilute alcohol solution to obtain antioxidant A;

[0018] S2. dissolving the secondary corrosion inhibitor in pure water to obtain antioxidant B;

[0019] S3. Mix the antioxidant A obtained in step S1 and the antioxidant B obtained in step S2 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0020] In a third aspect, the present invention provides a battery negative electrode current collecting disc, which is obtained by treating the battery negative electrode current collecting disc with a chromium-free copper antioxidant.

[0021] In a third aspect, the present invention provides a passivation method for a negative electrode current collector of a battery, comprising placing the negative electrode current collector to be used in the negative electrode current collector antioxidant, soaking it at 20 to 50°C for 2 to 5 minutes, washing it with water, first blowing away surface water droplets with cold air, and then drying it at 70 to 90°C for 10 to 20 minutes to obtain a passivated negative electrode current collector of the battery.

[0022] In a fourth aspect, the present invention also provides a lithium battery comprising the battery negative electrode current collecting disk.

[0023] In a fifth aspect, the present invention also provides applications of the lithium battery in new energy vehicles, electronic products, and energy storage devices.

[0024] In the chromium-free copper antioxidant for the negative electrode current collecting plate of a battery of the present invention, the main corrosion inhibitor forms a protective film on the copper surface or forms a stable complex with copper ions in different ways, among which tannic acid provides good adsorption and chelation, sodium molybdate can form an oxide film, and sodium hexametaphosphate has both complexation and phosphating effects, and sulfosalicylic acid also plays a complexation and acid protection role; the secondary corrosion inhibitor further enhances the stability and integrity of the protective film, which can not only reduce the formed oxides, but also promote the formation of new films during the reduction process, thereby enhancing the antioxidant capacity. At the same time, as a good chelating agent for copper, it can more thoroughly remove free copper ions in the solution, ensuring that the copper surface does not cause local corrosion due to ion movement, and also helps to build a more uniform and tight protective layer; in addition, the main corrosion inhibitor of the present invention is added to dilute alcohol, and the main corrosion inhibitor can be better dissolved in dilute alcohol.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The chromium-free copper antioxidant for the battery negative electrode current collector provided by the present invention can quickly form a film on the copper surface, forming a dense chemical conversion film within a few minutes, isolating the copper surface from the air and preventing air oxidation. The negative electrode current collector treated by the present invention can be left exposed for one month without changing color.

[0027] (2) It does not contain chromate and other harmful heavy metal components, reducing the potential threat to the environment and human health. The product made with this antioxidant has good wettability, can pass 46 dyne pen, has good solderability, and the surface after welding is relatively flat without tin leakage, and wastewater treatment is easy.

[0028] (3) The preparation method of the chromium-free copper antioxidant for the negative electrode current collector of the battery provided by the present invention is simple, low in cost, mild in working conditions, and can be washed with water or not. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a physical picture of the antioxidant test results of the battery negative electrode current collecting disc after antioxidant treatment of the present invention, A is the battery negative electrode current collecting disc prepared in Example 6, B is the battery negative electrode current collecting disc prepared in Comparative Example 6, C is the battery negative electrode current collecting disc prepared in Comparative Example 7, and D is the battery negative electrode current collecting disc prepared in Comparative Example 2.

[0030] Figure 2 Figure 1 is a physical diagram of the test results of the wettability of the battery negative electrode current collecting disk after antioxidant treatment of the present invention (diagram of no shrinkage of the dyne pen within 10 seconds), A is the battery negative electrode current collecting disk prepared in Example 6, B is the battery negative electrode current collecting disk prepared in Comparative Example 6, and C is the battery negative electrode current collecting disk prepared in Comparative Example 2.

[0031] Figure 3Figure 1 is a physical diagram of the weldability test results of the battery negative electrode current collecting disc after antioxidant treatment of the present invention, A is the battery negative electrode current collecting disc prepared in Example 6, B is the battery negative electrode current collecting disc prepared in Comparative Example 6, C is the battery negative electrode current collecting disc prepared in Comparative Example 7, and D is the battery negative electrode current collecting disc prepared in Comparative Example 2.

[0032] Figure 4 This is a physical picture of the test results of the nitric acid drip test (acid corrosion resistance) of the battery negative electrode current collecting disk after antioxidant treatment in Example 6 of the present invention.

[0033] Figure 5 This is a physical picture of the test results of the nitric acid drip test (acid corrosion resistance) of the battery negative electrode current collecting disk after antioxidant treatment in Comparative Example 7 of the present invention. DETAILED DESCRIPTION

[0034] The experimental methods in the following examples of the present invention, where specific conditions are not specified, are generally carried out under conventional conditions or conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0035] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0037] The present invention is further described in the following examples, but these examples are not intended to limit the scope of protection of the present invention.

[0038] Example 1

[0039] The specific preparation method of the chromium-free copper antioxidant for the battery negative electrode current collector and the battery negative electrode current collector prepared in this embodiment is as follows:

[0040] S1. Ethanol and pure water are mixed in a mass ratio of 20:100 to obtain a dilute alcohol solution, and the main corrosion inhibitors tannic acid and sodium molybdate are dissolved in the dilute alcohol solution to obtain an antioxidant A, wherein the concentration of tannic acid in the antioxidant A is 10 g / L and the concentration of sodium molybdate is 5 g / L;

[0041] S2. Dissolving the secondary corrosion inhibitor thiourea in pure water to obtain an antioxidant B, wherein the concentration of the corrosion inhibitor thiourea in the antioxidant B is 0.05 g / L;

[0042] S3. Mix antioxidant A and antioxidant B in a volume ratio of 6:4 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0043] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0044] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 70°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0045] Example 2

[0046] The specific preparation method of the chromium-free copper antioxidant for the battery negative electrode current collector and the battery negative electrode current collector prepared in this embodiment is as follows:

[0047] S1. Ethylene glycol and pure water are mixed in a mass ratio of 20:100 to obtain a dilute alcohol solution, and the main corrosion inhibitors sodium hexametaphosphate and tannic acid are dissolved in the dilute alcohol solution to obtain an antioxidant A, wherein the concentration of sodium hexametaphosphate in the antioxidant A is 10 g / L and the concentration of tannic acid is 15 g / L;

[0048] S2. Dissolving the secondary corrosion inhibitor EDTA·2Na in pure water to obtain an antioxidant B, wherein the concentration of EDTA·2Na in the antioxidant B is 3 g / L;

[0049] S3. Mix antioxidant A and antioxidant B in a volume ratio of 8:2 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0050] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0051] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 70°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0052] Example 3

[0053] The specific preparation method of the chromium-free copper antioxidant for the battery negative electrode current collector and the battery negative electrode current collector prepared in this embodiment is as follows:

[0054] S1. Methanol and pure water are mixed in a mass ratio of 30:100 to obtain a dilute alcohol solution, and the main corrosion inhibitors sulfosalicylic acid and sodium molybdate are dissolved in the dilute alcohol solution to obtain an antioxidant A, wherein the concentration of sulfosalicylic acid in the antioxidant A is 3 g / L and the concentration of sodium molybdate is 8 g / L;

[0055] S2. Dissolve 5 g / L of polyaspartic acid, a secondary corrosion inhibitor, in pure water to obtain an antioxidant B, wherein the concentration of polyaspartic acid in the antioxidant B is 5 g / L;

[0056] S3. Mix antioxidant A and antioxidant B in a volume ratio of 7:3 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0057] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0058] At 40°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 80°C for 12 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0059] Example 4

[0060] The specific preparation method of the chromium-free copper antioxidant for the battery negative electrode current collector and the battery negative electrode current collector prepared in this embodiment is as follows:

[0061] S1. 1,2-propylene glycol and pure water are mixed in a mass ratio of 30:100 to obtain a dilute alcohol solution, and the main corrosion inhibitors sodium hexametaphosphate, sodium molybdate, and sulfosalicylic acid are dissolved in the dilute alcohol solution to obtain an antioxidant A, wherein the concentration of sodium hexametaphosphate in the antioxidant A is 12 g / L, the concentration of sodium molybdate is 8 g / L, and the concentration of sulfosalicylic acid is 4 g / L;

[0062] S2. Dissolving the secondary corrosion inhibitor thiourea in pure water to obtain an antioxidant B, wherein the concentration of thiourea in the antioxidant B is 0.08 g / L;

[0063] S3. Mix antioxidant A and antioxidant B in a volume ratio of 7:3 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0064] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0065] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 75°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0066] Example 5

[0067] The specific preparation method of the chromium-free copper antioxidant for the battery negative electrode current collector and the battery negative electrode current collector prepared in this embodiment is as follows:

[0068] S1. 1,2-propylene glycol and pure water are mixed in a mass ratio of 30:100 to obtain a dilute alcohol solution, and the main corrosion inhibitors tannic acid, sodium hexametaphosphate, and sulfosalicylic acid are dissolved in the dilute alcohol solution to obtain an antioxidant A, wherein the antioxidant A has a tannic acid concentration of 15 g / L, a sodium hexametaphosphate concentration of 10 g / L, and a sulfosalicylic acid concentration of 3 g / L;

[0069] S2. Dissolving the secondary corrosion inhibitor thiourea in pure water to obtain an antioxidant B, wherein the concentration of thiourea in the antioxidant B is 0.06 g / L;

[0070] S3. Mix antioxidant A and antioxidant B in a volume ratio of 6:4 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0071] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0072] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 80°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0073] Example 6

[0074] The specific preparation method of the chromium-free copper antioxidant for the battery negative electrode current collector and the battery negative electrode current collector prepared in this embodiment is as follows:

[0075] S1. 1,2-propylene glycol and pure water are mixed in a mass ratio of 30:100 to obtain a dilute alcohol solution, and the main corrosion inhibitors tannic acid, sodium molybdate, sodium hexametaphosphate, and sulfosalicylic acid are dissolved in the dilute alcohol solution to obtain an antioxidant A, wherein the antioxidant A has a tannic acid concentration of 9 g / L, a sodium molybdate concentration of 15 g / L, a sodium hexametaphosphate concentration of 10 g / L, and a sulfosalicylic acid concentration of 3 g / L;

[0076] S2. Dissolve the secondary corrosion inhibitor EDTA·2Na in pure water to obtain an antioxidant B, wherein the concentration of EDTA·2Na in the antioxidant B is 2 g / L;

[0077] S3. Mix antioxidant A and antioxidant B in a volume ratio of 6:4 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0078] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0079] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 70°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0080] Example 7

[0081] The specific preparation method of the chromium-free copper antioxidant for the battery negative electrode current collector and the battery negative electrode current collector prepared in this embodiment is as follows:

[0082] S1. 1,2-propylene glycol and pure water are mixed in a mass ratio of 30:100 to obtain a dilute alcohol solution, and the main corrosion inhibitors tannic acid, sodium molybdate, and sulfosalicylic acid are dissolved in the dilute alcohol solution to obtain an antioxidant A, wherein the antioxidant A has a tannic acid concentration of 8 g / L, a sulfosalicylic acid concentration of 2 g / L, and a sodium molybdate concentration of 13 g / L;

[0083] S2. Dissolving the secondary corrosion inhibitor polyaspartic acid in pure water to obtain an antioxidant B, wherein the concentration of polyaspartic acid in the antioxidant B is 6 g / L;

[0084] S3. Mix antioxidant A and antioxidant B in a volume ratio of 8:2 to obtain a chromium-free copper antioxidant for a negative electrode current collector of a battery.

[0085] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0086] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 75°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0087] Comparative Example 1

[0088] The preparation method of the chromium-free copper antioxidant for the negative electrode current collector of the battery prepared in this embodiment is as follows:

[0089] Ethanol and pure water are mixed in a mass ratio of 30:100 to obtain a dilute alcohol solution, and tannic acid and sodium molybdate as main corrosion inhibitors are dissolved in the dilute alcohol solution to obtain a chromium-free copper antioxidant for a negative electrode current collecting disc of a battery, wherein the tannic acid concentration in the chromium-free copper antioxidant for a negative electrode current collecting disc of a battery is 10 g / L, and the sodium molybdate concentration is 5 g / L;

[0090] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0091] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 70°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0092] Comparative Example 2

[0093] The preparation method of the chromium-free copper antioxidant for the negative electrode current collector of the battery prepared in this embodiment is as follows:

[0094] Dissolving the secondary corrosion inhibitor EDTA·2Na in pure water to obtain a chromium-free copper antioxidant for a negative electrode current collecting disc of a battery, wherein the concentration of EDTA·2Na in the chromium-free copper antioxidant for a negative electrode current collecting disc of a battery is 3 g / L;

[0095] The battery negative electrode current collector disc to be treated with antioxidant is treated with a chromium-free copper antioxidant using the battery negative electrode current collector disc prepared above, and the specific steps are as follows:

[0096] At 30°C, the battery negative electrode current collector to be treated with antioxidant treatment was placed in the above-prepared chromium-free copper antioxidant for the battery negative electrode current collector and immersed for 3 minutes. After washing with water, the surface water droplets were blown away with cold air, and then baked with hot air at 70°C for 20 minutes until the surface moisture was dried to obtain a passivated battery negative electrode current collector.

[0097] Comparative Example 3

[0098] The negative electrode current collector to be anti-oxidized is directly washed with pure water, blown dry with cold air, and baked at 80 degrees Celsius for 10 minutes until the surface moisture is completely evaporated to obtain the battery negative electrode current collector.

[0099] Comparative Example 4

[0100] The difference between this comparative example and Example 6 is that tannic acid and sulfosalicylic acid are replaced by cyclohexanehexol hexaphosphate, and the remaining ingredients and preparation steps are the same as those in Example 1.

[0101] Comparative Example 5

[0102] The difference between this comparative example and Example 6 is that tannic acid is replaced by citric acid, and the remaining ingredients and preparation steps are the same as those in Example 1.

[0103] Comparative Example 6

[0104] The difference between this comparative example and Example 6 is that the dilute alcohol solution is replaced by a polyethylene glycol 200 aqueous solution with a concentration of 10 g / L, and the remaining ingredients and preparation steps are the same as those in Example 1.

[0105] Comparative Example 7

[0106] The difference between this comparative example and Example 6 is that the concentration of tannic acid in the main corrosion inhibitor of antioxidant A is 20 g / L, the concentration of sodium molybdate is 20 g / L, the concentration of sulfosalicylic acid is 10 g / L, and the concentration of sodium hexametaphosphate is 5 g / L, and the remaining ingredients and preparation steps are consistent with Example 1.

[0107] Comparative Example 8

[0108] The difference between this comparative example and Example 4 is that the concentration of EDTA·2Na in the main corrosion inhibitor of antioxidant A is 18 g / L, and the other ingredients and preparation steps are the same as those in Example 1.

[0109] Comparative Example 9

[0110] The difference between this comparative example and Example 6 is that antioxidant A and antioxidant B are mixed in a volume ratio of 2:8, and the remaining ingredients and preparation steps are the same as those in Example 1.

[0111] Comparative Example 10

[0112] The difference between this comparative example and Example 6 is that antioxidant A and antioxidant B are mixed in a volume ratio of 9:1, and the remaining ingredients and preparation steps are the same as those in Example 1.

[0113] Test Example 1: Antioxidant Performance Test

[0114] The negative electrode current collecting discs prepared in Examples 1 to 7 and Comparative Examples 1 to 10 of the present invention were subjected to an antioxidant performance test. The test method was to expose them to air for 30 days and observe the color and spots on the surface of the negative electrode current collecting discs. The specific test results are shown in Tables 1 and 2. Figures 1 to 3 shown.

[0115] Table 1 Antioxidation performance of negative electrode current collector

[0116] sample Antioxidant properties Example 1 No discoloration, spots, or patina Example 2 No discoloration, spots, or patina Example 3 No discoloration, spots, or patina Example 4 No discoloration, spots, or patina Example 5 No discoloration, spots, or patina Example 6 No discoloration, spots, or patina Example 7 No discoloration, spots, or patina Comparative Example 1 Severe oxidative discoloration, spots and verdigris Comparative Example 2 Severe oxidative discoloration, spots and verdigris Comparative Example 3 Severe oxidative discoloration, spots and verdigris Comparative Example 4 Oxidation discoloration, no spots or patina Comparative Example 5 Oxidation discoloration, no spots or patina Comparative Example 6 Oxidation discoloration, no spots or patina Comparative Example 7 Oxidation discoloration, no spots or patina Comparative Example 8 Oxidation discoloration, no spots or patina Comparative Example 9 Oxidation discoloration, no spots or patina Comparative Example 10 Oxidation discoloration, no spots or patina

[0117] From the results in Table 1, it can be seen that the surface of Examples 1 to 7 did not change color (see Figure 1A), the copper surface of the negative electrode collector disks of Comparative Examples 1 to 3 has been severely oxidized and discolored (see Figure 1 D), multiple spots and copper green appeared, and comparative examples 4 to 10 also partially oxidized and discolored (see Figure 1 B and C), it can be seen that the battery negative electrode current collecting disk prepared by the present invention is treated with a chromium-free copper antioxidant, which can significantly improve the antioxidant performance of the battery negative electrode current collecting disk.

[0118] Test Example 2: Wetting Performance Test

[0119] The negative electrode current collecting discs prepared in Examples 1 to 7 of the present invention and Comparative Examples 1 to 10 were subjected to a wettability test. The test method was as follows: the copper surface of the negative electrode current collecting disc was tested with a 46# dyne pen, and the shrinkage of the dyne pen was observed within 10 seconds (in order to prevent the copper surface of the negative electrode current collecting disc from being oxidized at high temperature and affecting the observation of the dyne pen, Examples 1 to 7 and Comparative Examples 1 to 10 were not subjected to high-temperature baking during the antioxidant treatment process, and only cold air drying was used). The test results are shown in Tables 2 and 3. Figure 2 .

[0120] Table 2 Wettability of negative electrode current collector

[0121] sample Wettability Example 1 No shrinkage Example 2 No shrinkage Example 3 No shrinkage Example 4 No shrinkage Example 5 No shrinkage Example 6 No shrinkage Example 7 No shrinkage Comparative Example 1 There is contraction Comparative Example 2 There is contraction Comparative Example 3 There is contraction Comparative Example 4 There is contraction Comparative Example 5 There is contraction Comparative Example 6 There is contraction Comparative Example 7 There is contraction Comparative Example 8 There is contraction Comparative Example 9 There is contraction Comparative Example 10 There is contraction

[0122] From Table 2 and Figure 2 The results showed that all of Examples 1 to 7 were qualified (no shrinkage after drawing, see Figure 2 A in the figure), all of the comparative examples 1 to 10 have shrinkage (see Figure 2 B and C), it can be seen that the wetting performance of the battery negative electrode current collecting disc prepared by the present invention is significantly improved by treating the battery negative electrode current collecting disc with a chromium-free copper antioxidant.

[0123] Test Example 3: Solderability Test

[0124] The negative electrode current collectors prepared in Examples 1 to 7 and Comparative Examples 1 to 10 of the present invention were subjected to a solderability test. The test method was as follows: the samples were placed in a tin furnace for 2 seconds for a tin immersion test. The tin furnace temperature was 280°C. The surface tin layer was observed. If the surface was uniform and smooth without any tin leakage or holes, it indicated good solderability. The test results are shown in FIG. Figure 3 .

[0125] Table 3 Weldability performance of negative electrode current collector

[0126]

[0127]

[0128] From Table 3 and Figure 3 It can be seen that there is no tin leakage in the examples, and the tin layer impregnated in the anti-oxidation films of Examples 1 to 7 is smooth (see Figure 3 A in the figure), while comparative examples 1 to 3 have more protrusions, holes, and poor uniformity (see Figure 3 D), there is a partial tin leakage phenomenon, the tin layer of the oxide film of Comparative Examples 4 to 10 has a small amount of protrusions, no holes, and tin leakage (see Figure 3 B and C), it can be seen that the battery negative electrode current collecting disk prepared by the present invention is treated with a chromium-free copper antioxidant, which can significantly improve the weldability of the battery negative electrode current collecting disk.

[0129] Test Example 4: Nitric Acid Drip Test

[0130] The negative electrode current collecting plates prepared in Examples 1 to 7 of the present invention and Comparative Examples 1 to 10 were subjected to a nitric acid drop test. The test method is as follows: a drop of nitric acid solution with a volume fraction of 40% is dropped on the surface of the sample to corrode the copper surface, and the time when the first bubble appears in the drop is observed. The later the bubble appears, the better the nitric acid resistance. The test results are shown in Tables 4 and Figure 4 、 Figure 5 .

[0131] Table 4 Corrosion performance of negative electrode current collector

[0132] sample Bubble appearance time / s Example 1 59 Example 2 48 Example 3 39 Example 4 45 Example 5 48 Example 6 51 Example 7 46 Comparative Example 1 4 Comparative Example 2 3 Comparative Example 3 1 Comparative Example 4 2 Comparative Example 5 3 Comparative Example 6 5 Comparative Example 7 2 Comparative Example 8 4 Comparative Example 9 3 Comparative Example 10 2

[0133] From Table 1 and Figures 4-5 The results show that the time for the first copper bubble to appear on the surface of the negative electrode current collecting plate samples of Examples 1 to 7 is later than 39 seconds (see Figure 4 ), while the first bubble appeared on the surface of the negative electrode collector disc samples of Comparative Examples 1 to 3 within 1s to 4s, and the first bubble appeared within 5 to 15s in Comparative Examples 4 to 10 (see Figure 5 ), it can be seen that the battery negative electrode current collecting disk prepared by the present invention is treated with a chromium-free copper antioxidant, which can significantly improve the (acid) corrosion resistance of the battery negative electrode current collecting disk.

[0134] For the sake of simplicity, the above embodiments only represent several implementation methods of the present invention. The description is relatively specific and detailed, but it should not be understood as limiting the scope of the invention. Those skilled in the art may combine and combine the different embodiments and features of the different embodiments described in this specification without any contradiction.

Claims

1. A chromium-free copper antioxidant for a negative electrode current collector of a battery, characterized in that: The chromium-free copper antioxidant for the negative electrode current collector of the battery includes an antioxidant A and an antioxidant B; the antioxidant A includes a main corrosion inhibitor and a dilute alcohol solution, the main corrosion inhibitor includes tannic acid and / or sulfosalicylic acid, and also includes sodium molybdate and / or sodium hexametaphosphate, the antioxidant B includes a secondary corrosion inhibitor and water, the secondary corrosion inhibitor is selected from one or more of thiourea, EDTA·2Na, and polyaspartic acid; the dilute alcohol is a mixture of alcohols and water, the alcohols are selected from one or more of methanol, ethanol, propylene glycol, n-propanol, and ethylene glycol, and the mass ratio of the alcohols to water is (10-30):100; the volume ratio of the antioxidant A to the antioxidant B is (5-8): (2-5); the antioxidant A includes tannic acid with a concentration of 5-15 g / L and / or sulfosalicylic acid with a concentration of 1-5 g / L, and also includes sodium molybdate and / or sodium hexametaphosphate, the concentration of 5-20 g / L of sodium molybdate and / or sodium hexametaphosphate with a concentration of 10-20 g / L; the mass volume ratio of the main corrosion inhibitor to the dilute alcohol solution in the antioxidant A agent is 10-45g: 1L, and the mass volume ratio of the secondary corrosion inhibitor to water in the antioxidant B agent is 0.05-15g: 1L; the antioxidant B agent includes one or more of thiourea with a concentration of 0.05-0.1 g / L, EDTA·2Na with a concentration of 1-5 g / L, and polyaspartic acid with a concentration of 2-10 g / L.

2. A method for preparing a negative electrode current collector of a battery, characterized in that: The battery negative electrode current collector disc is obtained by treating the battery negative electrode current collector disc according to claim 1 with a chromium-free copper antioxidant, comprising the following steps: S1. Dissolving the main corrosion inhibitor in a dilute alcohol solution to obtain antioxidant A; S2. dissolving the secondary corrosion inhibitor in pure water to obtain antioxidant B; S3, mixing the antioxidant A obtained in step S1 and the antioxidant B obtained in step S2 to prepare a chromium-free copper antioxidant for a negative electrode current collector of a battery; S4. Place the negative electrode current collector disc to be treated into the chromium-free copper antioxidant for the battery negative electrode current collector disc prepared in step S3, soak it at 20-50° C. for 2-5 minutes, wash it with water, blow off the water droplets on the surface with cold air, and then dry it at 70-90° C. for 10-20 minutes to obtain a passivated battery negative electrode current collector disc.

3. A battery negative electrode current collecting disk prepared by the preparation method according to claim 2.

4. A lithium battery comprising the negative electrode current collecting disk of claim 3.

5. Application of the lithium battery as claimed in claim 4 in new energy vehicles, electronic products, and energy storage devices.

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