Aqueous battery stainless steel current collector and preparation method thereof

Abstract

The invention provides an aqueous battery stainless steel current collector and a preparation method thereof, and solves the problems of poor binding force, narrow potential window, insufficient corrosion resistance and the like of the existing stainless steel current collector, the main preparation method comprises the following steps: S1, respectively preparing an adhesive aqueous solution and a film-forming additive aqueous solution; s2, mixing a carbon material, a binder aqueous solution and a film-forming additive aqueous solution according to a certain mass ratio, adding deionized water into the mixed material, adjusting the solid content and viscosity, uniformly stirring, and carrying out defoaming treatment to prepare slurry; s3, a stainless steel current collector is coated with the slurry to form a coating, and after high-temperature drying is conducted for a certain time, rolling is conducted to control the thickness of the coating; and S4, placing the stainless steel current collector coated with the coating in a micro-arc oxidation electrolyte, performing micro-arc oxidation treatment by taking the stainless steel current collector as an anode, performing coating treatment on the stainless steel current collector by using a carbon material, and forming a surface carburized composite layer in combination with a micro-arc oxidation technology, thereby effectively improving the performance defects.

Description

Technical Field

[0001] The present invention relates to the technical field of battery current collectors, and in particular to a stainless steel current collector for an aqueous battery and a preparation method thereof. Background Art

[0002] With the rapid development of the global economy and the continued growth of its population, energy demand has skyrocketed, while environmental pollution has also become increasingly severe. The active development of new energy sources has placed higher demands on energy storage systems to effectively address the problem of intermittent energy supply. Implementing safe, reliable, cost-effective, and environmentally friendly energy storage systems has become a major global challenge in the 21st century. Aqueous batteries, with their significant advantages such as high safety, low cost, low pollution, and extremely long service life, demonstrate enormous potential for large-scale energy storage applications.

[0003] However, aqueous electrolytes are highly corrosive, especially under high voltage conditions on the positive electrode side of the battery. Their electrochemical oxidation properties can cause severe corrosion of the current collector, leading to poor battery cycling stability. This problem poses a severe challenge to the screening and protection technology of current collector materials. Stainless steel, as a low-cost and relatively chemically stable metal current collector material, is widely used in aqueous batteries. However, due to its oxygen absorption corrosion reaction, its electrochemical stability still needs to be significantly improved. Under certain voltage conditions, some metal elements in the stainless steel mesh will undergo oxidative dissolution, which not only easily causes the electrode to fall off, but also triggers serious side reactions, adversely affecting the overall performance of the battery. In addition, the relatively smooth surface of stainless steel weakens the bonding between the electrode material and the current collector. Therefore, exploring an effective treatment method to enhance the bonding strength of the stainless steel current collector and improve its oxidation resistance and corrosion resistance is of great significance to promoting the development of aqueous batteries. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the existing technology. The present invention proposes a stainless steel current collector for aqueous batteries and a preparation method thereof, aiming to address the problems of poor bonding force, narrow potential window, insufficient corrosion resistance, etc. of the existing stainless steel current collector. The stainless steel current collector is coated with carbon material and combined with micro-arc oxidation technology to form a surface carburized composite layer, thereby effectively improving the above-mentioned performance defects.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a stainless steel current collector for an aqueous battery, comprising the following steps: S1. Prepare an adhesive aqueous solution and a film-forming additive aqueous solution respectively; S2. Mixing the carbon material, the binder aqueous solution, and the film-forming additive aqueous solution in a certain mass ratio, adding deionized water to the mixed material, adjusting the solid content and viscosity, stirring evenly, and performing a degassing treatment to prepare a slurry; S3, applying the slurry to a stainless steel current collector to form a coating, drying at high temperature for a certain period of time, and then rolling to control the coating thickness; S4. Place the coated stainless steel current collector in a micro-arc oxidation electrolyte and perform micro-arc oxidation treatment with the stainless steel current collector as the anode.

[0006] Furthermore, the mass fractions of the binder aqueous solution and the film-forming additive aqueous solution are both 2%-5%.

[0007] Furthermore, in step S2, the mass ratio of the carbon material, the binder aqueous solution, and the film-forming additive aqueous solution is 7-9:0.5-2.5:0.5.

[0008] Furthermore, in step S2, the carbon material is one or more of carbon black, carbon nanotubes, and graphene, the binder material is one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, sodium alginate, and polyvinyl alcohol, and the film-forming additive material is one or more of polyacrylic acid, sodium polyacrylate, agar, and carrageenan.

[0009] Furthermore, the specific steps of step S3 are drying at a temperature of 60° C.-90° C. for 6-12 hours, and accurately controlling the coating thickness to be 1 μm-5 μm after roller pressing.

[0010] Furthermore, in step S4, the voltage of the micro-arc oxidation treatment is 380V-450V, the current density is 1A / dm²-5A / dm², the frequency is 450Hz-600Hz, the duty cycle is 25%-35%, and the treatment time is 10-20min.

[0011] A stainless steel current collector for an aqueous battery is prepared by the above-mentioned method for preparing the stainless steel current collector for an aqueous battery.

[0012] Furthermore, the aqueous battery includes an aqueous lithium ion battery, an aqueous sodium ion battery, an aqueous zinc ion battery, an aqueous hydrogen ion battery, and an aqueous ammonium ion battery.

[0013] Compared with existing technologies, the present invention offers several advantages: by first applying a coating of a specific material and then performing micro-arc oxidation, the resulting composite layer combines the high electrical conductivity of carbon materials with excellent electrochemical corrosion resistance and strong adhesion to electrode materials. The unique structure created by micro-arc oxidation further enhances these properties. The composite layer increases surface roughness, significantly strengthening the adhesion between the current collector and the electrode material. Furthermore, the composite layer exhibits excellent corrosion resistance, effectively isolating the stainless steel from electrolyte attack, significantly improving the current collector's corrosion resistance in high-voltage environments. Furthermore, the composite layer modifies the electrochemical properties of the current collector surface, increasing the overpotential for hydrogen and oxygen evolution, and broadening the potential window for aqueous batteries. This technology ensures uniformity and density of the initial coating through a rational combination of binders and film-forming additives, paving the way for subsequent micro-arc oxidation to form a high-quality composite film. Testing has shown that compared to untreated stainless steel current collectors, the treated stainless steel current collectors exhibit a wider potential window, lower resistance, higher adhesion, and superior cycling stability. Therefore, the present invention has broad application prospects in the field of large-scale energy storage of aqueous batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them: Figure 1 The figures are UV absorption spectra of the electrolytes of the stainless steel current collectors obtained in Examples 1, 2, and 3 and Comparative Examples 1 and 2 after being oxidized at constant potential for 1 hour.

[0015] Figure 2 Graph showing the cycle stability test results of the stainless steel current collectors obtained in Examples 1, 2, and 3 and Comparative Examples 1 and 2 after loading the electrode materials. DETAILED DESCRIPTION

[0016] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0017] According to one embodiment of the present invention, Figure 1-Figure 2 Shown.

[0018] The present invention provides a stainless steel current collector for aqueous batteries with high binding strength, a wide potential window, high conductivity, and corrosion resistance. The treatment process includes coating the stainless steel current collector with a specific material, followed by micro-arc oxidation. The specific composition includes a carbon material (one or more of carbon black, carbon nanotubes, and graphene), a binder material (one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, sodium alginate, and polyvinyl alcohol), a film-forming additive material (one or more of polyacrylic acid, sodium polyacrylate, agar, and carrageenan), and micro-arc oxidation.

[0019] The specific preparation steps are as follows: Step S1: preparing a binder aqueous solution and a film-forming additive aqueous solution with a mass fraction of 2-5% respectively; Step S2: adding the binder solution and film-forming additive solution prepared in step S1 to a certain mass of carbon powder in a mass ratio of carbon material, binder, and film-forming additive of 7-9:0.5-2.5:0.5, and mixing thoroughly; Step S3: adding deionized water to the mixture obtained in step S2, adjusting the solid content and viscosity, stirring to uniformly disperse all substances, and performing degassing treatment to obtain the desired slurry; Step S4: coating the slurry prepared in step S3 onto a stainless steel current collector, and then placing it in a constant temperature drying oven and drying it at 60°C-90°C for 6-12 hours, with the coating thickness precisely controlled to be 1 μm-5 μm; Step S5: Roll-pressing the stainless steel current collector with modified coating obtained in step S4 to further improve the density of the coating; Step S6: Micro-arc oxidation. Using commercial micro-arc oxidation technology, the coated stainless steel current collector is placed in a specific micro-arc oxidation electrolyte. With the stainless steel current collector serving as the anode, micro-arc oxidation is performed under appropriate voltage, current, frequency, duty cycle, and other parameters. This forms a carburized composite layer with unique structure and properties on the surface of the stainless steel current collector.

[0020] The following describes the present invention in combination with a number of embodiments and comparative examples.

[0021] Example 1 This embodiment introduces a method for treating a stainless steel mesh current collector: First, proceed to steps S1-S4. Carbon black is selected as the carbon material, sodium carboxymethyl cellulose (CMC) as the binder, and polyacrylic acid (PAA) as the film-forming additive, with a mass ratio of 80:15:5. A 2% solution of CMC and a 5% solution of PAA are prepared and added to the carbon powder. Premix thoroughly, then add deionized water and thoroughly mix and degas. The resulting slurry is coated onto the surface of a stainless steel foil current collector to a thickness of 3 μm. After coating, the mixture is dried in an 80°C drying oven for 6 hours.

[0022] Then, step S5 is performed to roll-press the stainless steel current collector with the composite membrane, with the rolling pressure set to 30T, to obtain a stainless steel current collector with a uniform and dense coating.

[0023] Finally, step S6 is performed for micro-arc oxidation treatment. The coated stainless steel current collector is placed in a micro-arc oxidation electrolyte containing sodium phosphate, glycerol and additives. The stainless steel current collector is used as the anode, the voltage is set to 400 V, and the current density is set to 1A / dm², a frequency of 500Hz, a duty cycle of 30%, and a treatment time of 15min to form a composite layer on the surface of the stainless steel current collector.

[0024] Example 2 This embodiment describes a method for treating a stainless steel mesh current collector: First, proceed to steps S1-S4. Graphene is used as the carbon material, sodium carboxymethyl cellulose (CMC) as the binder, and polyvinyl alcohol (PVA) as the film-forming additive, with a mass ratio of 70:25:5. A 2% solution of CMC and a 5% solution of PVA are prepared and added. Premix thoroughly, then deionized water is added for thorough mixing and degassing. The resulting slurry is applied to the surface of a stainless steel foil current collector to a thickness of 5μm. After coating, the mixture is dried in an 80°C oven for 6 hours.

[0025] Then, step S5 of roller pressing is performed, and the roller pressing pressure is controlled to be 30T to obtain a stainless steel current collector with a uniform and dense coating.

[0026] Finally, step S6, micro-arc oxidation treatment, is performed. The stainless steel current collector is placed in a micro-arc oxidation electrolyte containing sodium silicate, ethylenediaminetetraacetic acid, and additives. The voltage is set to 450 V, the current density is 2 A / dm², the frequency is 600 Hz, the duty cycle is 35%, and the treatment time is 10 minutes. A composite layer is formed on the surface of the stainless steel current collector.

[0027] Example 3 This embodiment describes a method for treating a stainless steel mesh current collector: Complete steps S1-S4 first. Select carbon black as the carbon material, sodium alginate as the binder, and agar as the film-forming additive in a mass ratio of 80:15:5. Prepare a 5% solution of sodium alginate and a 3% solution of agar before adding them. Premix thoroughly, then add deionized water, mix thoroughly, and degas. Apply the resulting slurry to the surface of a stainless steel foil current collector to a thickness of 1 μm. Dry in an 80°C drying oven for 6 hours.

[0028] Then, step S5 of roller pressing is performed, and the roller pressing pressure is controlled to be 30T to obtain a stainless steel current collector with a uniform and dense coating.

[0029] Finally, step S6 is performed to place the stainless steel current collector in a micro-arc oxidation electrolyte containing sodium tungstate, potassium sodium tartrate, and additives. The voltage is set to 380 V, the current density is 1 A / dm², the frequency is 450 Hz, the duty cycle is 25%, and the treatment time is 12 minutes to form a composite layer on the surface of the stainless steel current collector.

[0030] Comparative Example Comparative Example 1: An untreated stainless steel mesh current collector was used as a comparative example.

[0031] Comparative Example 2: The stainless steel current collector was only subjected to coating treatment (steps S1-S5) without micro-arc oxidation treatment.

[0032] Comparative Example 3: The stainless steel current collector was only subjected to micro-arc oxidation treatment (step S6, performed according to the corresponding steps in Example 1), without coating treatment.

[0033] Using the stainless steel current collectors obtained in the above examples and comparative examples as the working electrode, platinum as the auxiliary electrode, and Ag / AgCl as the reference electrode, a 1 mol / L sodium sulfate solution was used as the electrolyte. Constant-potential oxidation, conductivity, and cyclic voltammetry tests were conducted using a three-electrode test system. Furthermore, Na0.44MnO2 was loaded as the positive electrode active material for peel strength testing. Aqueous sodium-ion batteries were also assembled and subjected to charge-discharge cycle testing.

[0034] Table 1 Table 2 Table 3 Table 1 shows the peel strength test results of the stainless steel current collectors obtained in Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2 after loading the electrode material. Table 2 shows the conductivity test results of the stainless steel current collectors obtained in Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2. Table 3 shows the potential window test results of the stainless steel current collectors obtained in Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2.

[0035] The peel strength test results in Table 1, the electrical conductivity of each current collector in Table 2, and the potential window test results of each current collector in Table 3 show that the bonding strength between each embodiment and the electrode material, its own electrical conductivity, and the inhibition of hydrogen and oxygen evolution and the increase in water decomposition potential are significantly higher than those of the stainless steel mesh current collector that is only coated or only micro-arc oxidation treated, as well as the untreated stainless steel mesh current collector.

[0036] Likewise, Figure 1 and Figure 2 As shown in Figure 1, the curve shows the UV absorption spectrum of the Fe and Cr concentrations dissolved in the electrolyte after oxidation of the stainless steel current collector working electrode at a constant potential of 2.5V for 1 hour. A comparison shows that the Fe and Cr absorption peaks corresponding to the stainless steel mesh current collector in each example are significantly reduced compared to the stainless steel mesh current collector obtained by coating alone without micro-arc oxidation treatment or the untreated control example. This demonstrates that the stainless steel current collector and treatment method proposed in the present invention can effectively reduce the amount of metal dissolved by oxidation in the stainless steel current collector and significantly improve its corrosion resistance. Figure 2 The test results show that the stainless steel current collector treated by the present invention can significantly improve the cycle stability of the electrode material, and the effect is better than that of only coating treatment.

[0037] The above embodiments are intended only 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 the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of protection of the technical solutions of the present invention.

Claims

1. A method for preparing a stainless steel current collector for an aqueous battery, characterized in that: The steps include: S1. Prepare an adhesive aqueous solution and a film-forming additive aqueous solution respectively; S2. Mixing the carbon material, the binder aqueous solution, and the film-forming additive aqueous solution in a certain mass ratio, adding deionized water to the mixed material, adjusting the solid content and viscosity, stirring evenly, and performing a degassing treatment to prepare a slurry; S3, applying the slurry to a stainless steel current collector to form a coating, drying at high temperature for a certain period of time, and then rolling to control the coating thickness; S4. Place the coated stainless steel current collector in a micro-arc oxidation electrolyte and perform micro-arc oxidation treatment with the stainless steel current collector as the anode.

2. The method for preparing a stainless steel current collector for an aqueous battery according to claim 1, wherein: The mass fractions of the binder aqueous solution and the film-forming additive aqueous solution are both 2%-5%.

3. The method for preparing a stainless steel current collector for an aqueous battery according to claim 1, wherein: In the step S2, the mass ratio of the carbon material, the binder aqueous solution, and the film-forming additive aqueous solution is 7-9:0.5-2.5:0.

5.

4. The method for preparing a stainless steel current collector for an aqueous battery according to claim 1, wherein: In step S2, the carbon material is one or more of carbon black, carbon nanotubes, and graphene; the binder material is one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, sodium alginate, and polyvinyl alcohol; and the film-forming additive material is one or more of polyacrylic acid, sodium polyacrylate, agar, and carrageenan.

5. The method for preparing a stainless steel current collector for an aqueous battery according to claim 1, wherein: The specific steps of step S3 are drying at a temperature of 60° C.-90° C. for 6-12 hours, and accurately controlling the coating thickness to be 1 μm-5 μm after roller pressing.

6. The method for preparing a stainless steel current collector for an aqueous battery according to claim 1, wherein: In step S4, the voltage of the micro-arc oxidation treatment is 380V-450V, the current density is 1A / dm²-5A / dm², the frequency is 450Hz-600Hz, the duty cycle is 25%-35%, and the treatment time is 10-20min.

7. A stainless steel current collector for an aqueous battery, characterized in that: The aqueous battery stainless steel current collector is prepared by the preparation method of any one of claims 1 to 6.

8. The stainless steel current collector for aqueous batteries according to claim 7, characterized in that: The aqueous batteries include aqueous lithium ion batteries, aqueous sodium ion batteries, aqueous zinc ion batteries, aqueous hydrogen ion batteries, and aqueous ammonium ion batteries.

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