Aluminum-based functional current collector for an anode-free sodium battery and method for preparing the same

Abstract

This invention discloses an aluminum-based functional current collector for a negative electrode-free sodium battery and its preparation method, relating to the field of sodium battery technology. The method includes the following steps: aluminum foil is plasma-treated, then immersed in a metal nitrate alcohol solution, removed and dried, followed by magnetron sputtering of a thin aluminum layer to obtain a pretreated aluminum foil, and then chemical vapor deposition to obtain a carbon nanofiber-modified aluminum foil; the carbon nanofiber-modified aluminum foil is then spray-coated with a modified chitosan solution, dried, and then subjected to a second spray coating and drying to obtain the aluminum-based functional current collector. This invention sequentially performs plasma treatment, metal nitrate immersion, magnetron sputtering of a thin aluminum layer, carbon nanofiber modification, and spray coating with modified chitosan on the aluminum foil substrate, improving the uniform nucleation and deposition of sodium ions on the current collector surface, and further enhancing the rate performance of the negative electrode-free sodium battery.

Description

Technical Field

[0001] This invention relates to the field of sodium battery technology, specifically to an aluminum-based functional current collector for a negative electrode-free sodium battery and its preparation method. Background Technology

[0002] With the rapid development of the new energy industry, high-energy-density, low-cost, and high-safety energy storage batteries have become a research hotspot. Sodium batteries, due to the abundant and widely distributed nature of sodium resources, their low cost, and the similarity in electrochemical performance to lithium-ion batteries, are considered to be the next generation of energy storage devices with great application potential, especially in large-scale energy storage and electric vehicles, where they possess irreplaceable advantages. Among them, anode-free sodium batteries, with their simplified structure, higher energy density, lower manufacturing cost, and superior safety, further enhance the application potential of sodium batteries and have become a key research direction in the current sodium battery field. Currently, commercial aluminum foil is the preferred substrate material for current collectors in anode-free sodium batteries due to its low density, low cost, and superior thermodynamic inertness to sodium compared to copper foil. However, pure aluminum foil has many inherent defects that make it difficult to meet the high-performance requirements of anode-free sodium batteries. These inherent defects are concentrated in the fact that pure aluminum foil has a smooth surface and poor sodium affinity, making it difficult for sodium ions to nucleate on its surface and resulting in uneven deposition, which easily leads to the formation of sodium dendrites. The growth of sodium dendrites not only causes short circuits inside the battery but also exacerbates the irreversible loss of active sodium, reducing the battery's cycle life. Furthermore, the bonding force between pure aluminum foil and subsequent functional coatings (such as carbon materials and sodium-affinity modified layers) is weak, and the coating is prone to peeling off during long-term battery cycling, leading to failure of the current collector function. In addition, the surface structure of conventional aluminum foil is simple and cannot provide sufficient space for sodium deposition, making it difficult to suppress the volume expansion during the sodium deposition process, further shortening the battery's cycle life. Therefore, in order to solve the above problems, it is of great practical significance to prepare an aluminum-based functional current collector for sodium batteries without negative electrodes. Summary of the Invention

[0003] The purpose of this invention is to provide an aluminum-based functional current collector for sodium batteries without negative electrodes and its preparation method, so as to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery includes the following steps: Step 1: After plasma treatment, the aluminum foil is immersed in a metal nitrate alcohol solution, removed and dried, and then magnetron sputtered to form a thin aluminum layer to obtain the pretreated aluminum foil. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition to obtain carbon nanofiber modified aluminum foil; Step 3: Take the modified chitosan solution and spray it onto the carbon nanofiber modified aluminum foil once. After drying, spray it a second time and dry it to obtain the aluminum-based functional current collector.

[0005] Preferably, the metal nitrate alcohol solution comprises nickel nitrate hexahydrate and cobalt nitrate hexahydrate in a molar concentration ratio of 1:(0.5-3); Preferably, the plasma treatment uses Ar, the Ar flow rate is 5 sccm, and the plasma treatment time is 3-8 min; Preferably, the process parameters for magnetron sputtering are: sputtering power of 30-45W and Ar flow rate of sputtering atmosphere of 30-45 sccm; More preferably, the thickness of the thin aluminum layer is 5-10 nm; Preferred process parameters for chemical vapor deposition are as follows: Ar is introduced at a flow rate of 160-200 sccm, and the temperature is increased to 400-450℃ at a heating rate of 10-20℃ / min. Then, Ar is turned off, H2 is introduced at a flow rate of 120-150 sccm, and the temperature is held for 30-40 min before H2 is turned off. Then, Ar is introduced at a flow rate of 180-200 sccm, and the temperature is increased to 580-600℃ at a heating rate of 10-20℃ / min. The atmosphere is adjusted to be a mixture of Ar, H2 and C2H2, and the temperature is held for 5-10 min before H2 and C2H2 are turned off and the mixture is cooled. More preferably, the flow rates of each gas in the mixture are: Ar 80-100 sccm, H2 20-30 sccm, and C2H2 20-30 sccm. Preferably, the preparation steps of the modified chitosan solution are as follows: carboxymethyl chitosan is dissolved in deionized water by stirring, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 4-6 hours, 1,2,4,5-phenyltetramine tetrahydrochloride is added, and the reaction is continued for 8-10 hours. Sodium selenite is then added, and the reaction is carried out at 45-50℃ for 5-6 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in acetic acid solution by stirring to obtain the modified chitosan solution. More preferably, the modified chitosan comprises the following raw materials in parts by weight: 1 part carboxymethyl chitosan, 0.8-1.0 parts 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.3-0.5 parts N-hydroxysuccinimide, 0.8-1.2 parts 1,2,4,5-phenyltetramine tetrahydrochloride, and 2-3 parts sodium selenite; Preferably, the modified chitosan in the modified chitosan solution has a mass ratio of 1-3 wt%.

[0006] Preferably, the total coating amount of modified chitosan in the aluminum-based functional current collector is 10-30 μL / cm.2 The thickness of the aluminum foil is 10-20μm. An aluminum-based functional current collector for sodium-ion batteries without negative electrodes is prepared by the above-described method.

[0007] Compared with the prior art, the beneficial effects achieved by the present invention are: 1. This invention sequentially performs plasma treatment, metal nitrate impregnation, magnetron sputtering of a thin aluminum layer, CVD introduction of carbon nanofiber modification, and spray coating of modified chitosan on an aluminum foil substrate. Among these processes, plasma treatment effectively enhances the surface activity of the aluminum foil substrate. Then, catalytic active sites are introduced through metal nitrates (nickel nitrate hexahydrate and cobalt nitrate hexahydrate). Combined with magnetron sputtering of a thin aluminum layer, the catalytic active sites are fixed between the aluminum foil and the thin aluminum layer, which synergistically improves the bonding between the carbon nanofibers and the aluminum foil. In addition, the thin aluminum layer can also inhibit the agglomeration process of Ni and Co catalyst particles during catalytic growth, resulting in a uniform three-dimensional porous framework that is conducive to Na metal deposition. 2. This invention utilizes a spray coating method to introduce a modified chitosan coating onto the surface of carbon nanofiber-modified aluminum foil. By adjusting the concentration of the chitosan solution, the electron-ion conduction pathway within the three-dimensional porous framework remains undisturbed, preserving certain porous channels and simultaneously improving the interfacial bonding between the framework and the aluminum foil. The modified chitosan is grafted with 1,2,4,5-phenyltetramine and modified with selenide to introduce sodium-loving groups such as selenide and amino groups, enhancing its chemical adsorption capacity for sodium ions, improving the sodium affinity of the current collector, and accelerating the migration rate of sodium ions. Combined with the three-dimensional porous framework, this allows sodium ions to uniformly nucleate and deposit on the surface of the current collector, inhibiting the growth of sodium dendrites and avoiding the risk of short circuits caused by sodium dendrites piercing the separator in a negative electrode-free sodium battery, further improving the rate cycle performance of the negative electrode-free sodium battery. Detailed Implementation

[0008] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0009] It should be noted that the following quantities are by weight, and there are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include: The preparation steps of carboxymethyl chitosan are as follows: Take 2 parts of chitosan and 8 parts of solid sodium hydroxide and ball mill and alkalize for 5 hours. After alkalization, add 8 parts of solid sodium chloroacetate and continue ball milling for 5 hours. Add 50 parts of deionized water and adjust the pH of the system to 7. Centrifuge and collect the filtrate for alcohol precipitation. Filter, wash and dry to obtain carboxymethyl chitosan. The degree of deacetylation of chitosan is ≥90%, and it was purchased from Aladdin. In the following examples, parts refer to parts by weight, and all raw materials mentioned above and others not mentioned are commercially available.

[0010] Example 1: This example provides a method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery, including the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.005mol / L cobalt nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 160 sccm, and heat to 400℃ at a rate of 10℃ / min. Then turn off Ar and introduce H2 at a flow rate of 120 sccm. Hold for 40 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Heat to 580℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 5 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 80 sccm, H2 30 sccm, and C2H2 20 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 1 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 10 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 4 hours, 0.8 parts of 1,2,4,5-phenyltetramine tetrahydrochloride are added, and the reaction continues for 8 hours. Then, 2 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 5 hours. After centrifugation, filtration, washing, and drying, the modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0011] Example 2: This example provides a method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery, including the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.01mol / L cobalt nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 180 sccm, and heat to 400℃ at a rate of 10℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 30 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Heat to 600℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 6 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 80 sccm, H2 20 sccm, and C2H2 20 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 4 hours, 0.8 parts of 1,2,4,5-phenyltetramine tetrahydrochloride are added, and the reaction continues for 8 hours. Then, 2 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 6 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% (v / v) acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0012] Example 3: This example provides a method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery, including the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.02mol / L cobalt nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 200 sccm, and raise the temperature to 450℃ at a rate of 10℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 30 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Raise the temperature to 600℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 8 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 100 sccm, H2 20 sccm, and C2H2 30 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 5 hours, 1.0 part of 1,2,4,5-phenyltetramine tetrahydrochloride is added, and the reaction is continued for 10 hours. Then, 2 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 5 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0013] Example 4: This example provides a method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery, including the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.02mol / L cobalt nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 200 sccm, and raise the temperature to 450℃ at a rate of 20℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 30 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Raise the temperature to 600℃ at a rate of 20℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 8 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 80 sccm, H2 20 sccm, and C2H2 30 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 6 hours, 1.2 parts of 1,2,4,5-phenyltetramine tetrahydrochloride are added, and the reaction is continued for 10 hours. Then, 2 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 5 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0014] Example 5: This example provides a method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery, including the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.03mol / L cobalt nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 200 sccm, and raise the temperature to 450℃ at a rate of 20℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 40 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Raise the temperature to 600℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 8 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 100 sccm, H2 20 sccm, and C2H2 30 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 5 hours, 1.2 parts of 1,2,4,5-phenyltetramine tetrahydrochloride are added, and the reaction is continued for 10 hours. Then, 2 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 5 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0015] Example 6: This example provides a method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery, including the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.02mol / L cobalt nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 200 sccm, and raise the temperature to 420℃ at a rate of 20℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 40 min, then turn off H2 and introduce Ar at a flow rate of 180 sccm. Raise the temperature to 600℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 8 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 90 sccm, H2 30 sccm, and C2H2 30 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 5 hours, 1.0 part of 1,2,4,5-phenyltetramine tetrahydrochloride is added, and the reaction continues for 8 hours. Then, 3 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 6 hours. After centrifugation, filtration, washing, and drying, the modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% (v / v) acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0016] Comparative Example 1: As a control experiment for Example 3, the difference is that the modified chitosan was not selenized, and the experiment included the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.02mol / L cobalt nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 200 sccm, and raise the temperature to 450℃ at a rate of 10℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 30 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Raise the temperature to 600℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 8 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 100 sccm, H2 20 sccm, and C2H2 30 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added. The pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 5 hours, 1.0 part of 1,2,4,5-phenyltetramine tetrahydrochloride is added. The reaction is continued for 10 hours. After centrifugation, filtration, washing, and drying, the modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% acetic acid solution by stirring and adjusting the pH to 5 to obtain the modified chitosan solution.

[0017] Comparative Example 2: As a control experiment for Example 3, the difference is that the metal nitrate alcohol solution used only nickel nitrate hexahydrate, and included the following steps: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is wetted, it is removed and dried at 75℃ for 2 min. Then, a 5nm thick aluminum layer is sputtered by magnetron sputtering to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent and 0.01mol / L nickel nitrate hexahydrate. The magnetron sputtering process parameters are: sputtering power of 30W and Ar flow rate of 40sccm. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 200 sccm, and raise the temperature to 450℃ at a rate of 10℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 30 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Raise the temperature to 600℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 8 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 100 sccm, H2 20 sccm, and C2H2 30 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 5 hours, 1.0 part of 1,2,4,5-phenyltetramine tetrahydrochloride is added, and the reaction is continued for 10 hours. Then, 2 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 5 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0018] Comparative Example 3: As a control experiment for Example 3, the difference is that magnetron sputtering of a thin aluminum layer was not performed, and the following steps were included: Step 1: A 12μm thick aluminum foil is subjected to plasma treatment with Ar (5sccm) for 5 min, then immersed in a metal nitrate alcohol solution. After the surface is moistened, it is removed and dried at 75℃ for 2 min to obtain the pretreated aluminum foil. The metal nitrate alcohol solution includes the following raw material components: anhydrous ethanol as solvent, 0.01mol / L nickel nitrate hexahydrate and 0.02mol / L cobalt nitrate hexahydrate. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition. Place it in a plasma-enhanced CVD tube furnace, introduce Ar at a flow rate of 200 sccm, and raise the temperature to 450℃ at a rate of 10℃ / min. Then turn off Ar and introduce H2 at a flow rate of 150 sccm. Hold for 30 min, then turn off H2 and introduce Ar at a flow rate of 200 sccm. Raise the temperature to 600℃ at a rate of 10℃ / min. Adjust the atmosphere to a mixture of Ar, H2, and C2H2. Hold for 8 min, then turn off H2 and C2H2. Cool to obtain carbon nanofiber modified aluminum foil. The flow rates of each gas in the mixture are: Ar 100 sccm, H2 20 sccm, and C2H2 30 sccm. Step 3: A modified chitosan solution is used to spray-coat carbon nanofiber modified aluminum foil once, followed by drying. A second spray-coating and drying process is then performed to obtain an aluminum-based functional current collector. The modified chitosan in the solution comprises 2 wt% of the modified chitosan, and the total coating amount of modified chitosan in the aluminum-based functional current collector is 20 μL / cm². 2 ; The preparation steps of the modified chitosan solution are as follows: 1 part of carboxymethyl chitosan is dissolved in 60 parts of deionized water by stirring. Then, 1.0 part of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.5 part of N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 5 hours, 1.0 part of 1,2,4,5-phenyltetramine tetrahydrochloride is added, and the reaction is continued for 10 hours. Then, 2 parts of sodium selenite are added, and the reaction is carried out at 50℃ for 5 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in a 0.8% acetic acid solution by stirring, and the pH is adjusted to 5 to obtain the modified chitosan solution.

[0019] Performance testing: Using the aluminum-based current collectors prepared in Examples 1-6 and Comparative Examples 1-3 as negative electrodes, Celgard 2340 as separators, 1M sodium trifluoromethanesulfonate dissolved in diethylene glycol dimethyl ether as electrolyte, and sodium iron pyrophosphate as positive electrode, a sodium battery without negative electrode was assembled. The first-cycle discharge capacity at 1C rate and the capacity retention rate after 300 cycles were tested and the data are recorded in Table 1. Table 1

[0020] Conclusion: Example 3 exhibits the best sodium affinity and chemical stability compared to the other examples, maintaining a high capacity even after 300 cycles; Comparative Example 1, serving as a control for Example 3, did not undergo selenization, resulting in fewer sodium-affinity groups and a lower capacity retention rate during cycling; Comparative Example 2, using single nickel catalysis, experienced rapid capacity decay; Comparative Example 3, serving as a control for Example 3, lacked a magnetron sputtered thin aluminum layer, resulting in poor interfacial bonding and a significant decrease in capacity retention during long-term cycling.

[0021] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery, characterized in that, Includes the following steps: Step 1: After plasma treatment, the aluminum foil is immersed in a metal nitrate alcohol solution, removed and dried, and then magnetron sputtered to form a thin aluminum layer to obtain the pretreated aluminum foil. Step 2: Take the pretreated aluminum foil and perform chemical vapor deposition to obtain carbon nanofiber modified aluminum foil; Step 3: Take the modified chitosan solution and spray it onto the carbon nanofiber modified aluminum foil once. After drying, spray it a second time and dry it to obtain the aluminum-based functional current collector.

2. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 1, characterized in that, The metal nitrate alcohol solution comprises nickel nitrate hexahydrate and cobalt nitrate hexahydrate in a molar concentration ratio of 1:(0.5-3); the plasma treatment uses Ar, with an Ar flow rate of 5 sccm and a plasma treatment time of 3-8 min.

3. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 1, characterized in that, The magnetron sputtering process parameters are: sputtering power of 30-45W, flow rate of Ar sputtering atmosphere of 30-45sccm; and the thickness of the thin aluminum layer of 5-10nm.

4. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 1, characterized in that, The process parameters for chemical vapor deposition are as follows: Ar is introduced at a flow rate of 160-200 sccm, and the temperature is increased to 400-450℃ at a heating rate of 10-20℃ / min. Then, Ar is turned off, H2 is introduced at a flow rate of 120-150 sccm, and the temperature is held for 30-40 min before H2 is turned off. Then, Ar is introduced at a flow rate of 180-200 sccm, and the temperature is increased to 580-600℃ at a heating rate of 10-20℃ / min. The atmosphere is adjusted to be a mixture of Ar, H2 and C2H2, and the temperature is held for 5-10 min before H2 and C2H2 are turned off and the mixture is cooled.

5. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 4, characterized in that, The flow rates of each gas in the mixture are as follows: Ar is 80-100 sccm, H2 is 20-30 sccm, and C2H2 is 20-30 sccm.

6. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 1, characterized in that, The preparation steps of the modified chitosan solution are as follows: carboxymethyl chitosan is dissolved in deionized water by stirring, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide are added, and the pH of the system is adjusted to 5 with hydrochloric acid. After reacting for 4-6 hours, 1,2,4,5-phenyltetramine tetrahydrochloride is added, and the reaction is continued for 8-10 hours. Sodium selenite is then added, and the reaction is carried out at 45-50℃ for 5-6 hours. After centrifugation, filtration, washing, and drying, modified chitosan is obtained. The modified chitosan is then dissolved in acetic acid solution by stirring to obtain the modified chitosan solution.

7. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 6, characterized in that, The modified chitosan comprises the following raw materials in parts by weight: 1 part carboxymethyl chitosan, 0.8-1.0 parts 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.3-0.5 parts N-hydroxysuccinimide, 0.8-1.2 parts 1,2,4,5-phenyltetramine tetrahydrochloride, and 2-3 parts sodium selenite.

8. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 6, characterized in that, The modified chitosan solution contains 1-3 wt% modified chitosan.

9. The method for preparing an aluminum-based functional current collector for a negative electrode-free sodium battery according to claim 1, characterized in that, The sum of the primary and secondary spray coating amounts of modified chitosan in the aluminum-based functional current collector is 10-30 μL / cm. 2 The thickness of the aluminum foil is 10-20 μm.

10. An aluminum-based functional current collector for a negative electrode-free sodium battery, characterized in that, It is prepared by any one of the preparation methods in claims 1-9.

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