A high sodium affinity carbon-coated aluminum foil and a method for preparing the same
Patent Information
- Application Number
- CN202610967843.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-01
- Publication Date
- 2026-09-22
AI Technical Summary
近年来，研究者尝试将铝箔拓展至无负极钠金属电池的负极集流体应用，但裸铝箔表面与钠的亲和性较差，钠金属在其表面呈随机成核、平面堆积，极易诱发枝晶生长，导致电池快速失效，为改善铝箔的亲钠性，现有技术主要采用以下方法：1）在铝箔表面涂覆氮掺杂、硫掺杂或磷掺杂的碳层，然而，单一杂原子掺杂对钠成核的诱导能力有限，且难以有效缓冲钠金属的体积膨胀；2）构建多孔碳骨架，应对涂层的体积膨胀，但缺乏亲钠活性位点；
本发明通过向纺丝溶液中引入SiO2硬模版与PMMA造孔剂，通过碳化和碱刻蚀制成多级孔碳纤维材料，有效缓冲循环中的体积膨胀，增大电解液与碳涂层之间的接触面积，拓宽钠离子通量，降低局部电流密度，且该孔道结构有效锚定碳包覆金属颗粒，另外，碳包覆金属颗粒由氧化锰、氧化铁和盐酸多巴胺混合碳化得到，提供亲钠成核位点；涂层中进一步引入组合金属盐掺杂生物质碳，用以填充间隙，金属盐中，偏钒酸铵增强对钠离子的静电吸附，硫酸钠和硫酸锌促进钠离子在涂层和电解液界面的传输，氯化亚锡与硫酸钠组合掺杂生物质碳，Sn提供合金化亲钠位点、Na⁺促进离子传输，二者协同优化涂层的离子传输动力学和界面稳定性；利用多孔径碳纤维、掺杂型生物质碳及PVDF按特定比例复配，提升无负极钠金属电池的循环稳定性。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of battery technology, specifically to a highly sodium-affinity carbon-coated aluminum foil and its preparation method. Background Technology
[0002] As the global energy structure shifts towards cleaner and lower-carbon energy, electrochemical energy storage technology is playing an increasingly crucial role in grid connection of new energy power generation, peak shaving of smart grids, and electric vehicle power systems. Sodium-ion batteries, due to the abundance and wide distribution of sodium in the Earth's crust and their low cost, are considered one of the most promising technological routes in the field of large-scale energy storage. Aluminum foil is widely used as the positive electrode current collector in sodium-ion batteries due to its low cost, good conductivity, and stability within the sodium potential window. In recent years, researchers have attempted to extend the application of aluminum foil as the negative electrode current collector in sodium metal-free batteries. However, the surface of bare aluminum foil has poor affinity with sodium, and sodium metal randomly nucleates and accumulates in a planar manner on its surface, which easily induces dendrite growth, leading to rapid battery failure. To improve the sodium affinity of aluminum foil, existing technologies mainly employ the following methods: 1) Coating the surface of aluminum foil with a nitrogen-doped, sulfur-doped, or phosphorus-doped carbon layer. However, the ability of single heteroatom doping to induce sodium nucleation is limited, and it is difficult to effectively buffer the volume expansion of sodium metal; 2) Constructing a porous carbon framework to cope with the volume expansion of the coating, but lacking sodium-affinity active sites. Therefore, it is of great significance to prepare a carbon-coated aluminum foil in order to improve the sodium affinity of aluminum foil. Summary of the Invention
[0003] The purpose of this invention is to provide a highly sodium-affinity carbon-coated aluminum foil 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 a highly sodium-affinity carbon-coated aluminum foil includes the following steps: Step 1: Place silica, polymethyl methacrylate, polyacrylonitrile, and carbon-coated metal particles in N,N-dimethylformamide and stir to obtain a spinning solution. Obtain nanofibers by electrospinning, heat-treat, place in sodium hydroxide solution, etch, wash with water, and dry to obtain porous carbon fibers. Step 2: Mix porous carbon fibers, doped biomass carbon materials and polyvinylidene fluoride, disperse them in N-methyl-2-pyrrolidone, stir evenly to obtain a slurry, coat it on the surface of aluminum foil, and dry it to obtain a highly sodium-loving carbon-coated aluminum foil. Preferably, the spinning solution in step 1 comprises the following components by weight: 0.4-0.6 parts silica, 0.3-0.5 parts polymethyl methacrylate, 0.7-1 parts polyacrylonitrile, 0.2-0.5 parts carbon-coated metal particles, and 10-12 parts N,N-dimethylformamide; Preferably, the preparation steps of carbon-coated metal particles are as follows: manganese oxide and iron oxide are placed in Tris-HCl buffer solution, dopamine hydrochloride is added and stirred for 24 hours, then filtered, and carbonized at 500-600℃ for 2-3 hours under argon atmosphere to obtain carbon-coated metal particles. More preferably, the mass ratio of manganese oxide to iron oxide to dopamine hydrochloride is 1:(2.2-6.8):(0.3-0.8). Preferably, the electrospinning process parameters are: feed speed of 0.8-1 mL / h, voltage of 15-18 kV, and distance between needle and collector of 15-20 cm; Preferably, the heat treatment process parameters are: after pre-oxidation at 200-220℃ for 2-3 hours, calcination at 700-800℃ for 2-4 hours under an argon atmosphere; Preferably, the concentration of the sodium hydroxide solution is 2-3 mol / L, and the etching time is 18-24 h; Preferably, the mass ratio of porous carbon fiber to doped biomass carbon material in the slurry is (80-95):(5-20); the coating thickness of the slurry is 0.02-0.03 mm. Preferably, the preparation steps of the doped biomass carbon material are as follows: after mixing and stirring the biomass material with the metal salt solution for 2-3 hours, pre-freezing at -50~-60℃ for 5-8 hours, freeze-drying, carbonizing, and then treating at 600-700℃ for 1-2 hours under an argon atmosphere, washing and drying to obtain the doped biomass carbon material. Preferably, the metal salt solution includes one or a combination of two of ammonium metavanadate, sodium sulfate, zinc sulfate, and stannous chloride; More preferably, the mass ratio of the biomass material to the metal salt in the metal salt solution is 10:(0.2-0.5); the biomass material is preferably bamboo powder; A highly sodium-affinity carbon-coated aluminum foil is prepared by the above-described preparation method.
[0005] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention introduces a SiO2 hard template and PMMA pore-forming agent into the spinning solution, and then produces a multi-level porous carbon fiber material through carbonization and alkaline etching. This effectively buffers volume expansion during cycling, increases the contact area between the electrolyte and the carbon coating, broadens the sodium ion flux, and reduces local current density. Furthermore, the pore structure effectively anchors carbon-coated metal particles. These carbon-coated metal particles are obtained by carbonization of a mixture of manganese oxide, iron oxide, and dopamine hydrochloride, providing sodium-affinity nucleation sites. The coating is further incorporating combined metal salts doped with biomass carbon to fill gaps. Among the metal salts, ammonium metavanadate enhances the electrostatic adsorption of sodium ions, sodium sulfate and zinc sulfate promote sodium ion transport at the coating-electrolyte interface, and stannous chloride and sodium sulfate are combined to dope the biomass carbon. Sn provides alloying sodium-affinity sites, and Na⁺ promotes ion transport. These two elements synergistically optimize the ion transport kinetics and interfacial stability of the coating. By using a specific ratio of porous carbon fiber, doped biomass carbon, and PVDF, the cycling stability of the anode-free sodium metal battery is improved. Detailed Implementation
[0006] 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.
[0007] 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 biomass material was bamboo charcoal powder with a particle size of 100 mesh; the polyvinylidene fluoride (PVDF) was grade KF7200; the polymethyl methacrylate (PMMA) had a molecular weight of 80,000; the polyacrylonitrile (PAC) had a molecular weight of 60,000; the silica was obtained by mixing tetrapropoxysilane, ammonia, ethanol, and deionized water in a volume ratio of 17:8:350:55, stirring at 60°C for 12 hours, and then centrifuging and drying; the pH of the Tris-HCl buffer solution was 8.5. In the following examples, parts refer to parts by weight, and all raw materials mentioned above and others not mentioned are commercially available.
[0008] Example 1: This example provides a method for preparing a highly sodium-affinity carbon-coated aluminum foil, specifically including the following steps: Step 1: According to the mass ratio, 0.5 parts of silica, 0.4 parts of polymethyl methacrylate, 0.8 parts of polyacrylonitrile, and 0.3 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are obtained by extrusion. After pre-oxidation at 200℃ for 2 h, the nanofibers are calcined at 750℃ for 2 h under an argon atmosphere. Then, the nanofibers are placed in a 2 mol / L sodium hydroxide solution and etched for 24 h. After washing and drying, porous carbon fibers with a diameter of 118 nm are obtained. Step 2: After mixing and stirring the biomass material with ammonium metavanadate solution for 2 hours, pre-freeze at -60℃ for 6 hours, freeze-dry, then carbonize, and treat at 650℃ for 2 hours under argon atmosphere, then wash and dry to obtain doped biomass carbon material. Step 3: According to the mass ratio, mix 85 parts of porous carbon fiber, 15 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride, disperse them in N-methyl-2-pyrrolidone, stir evenly to obtain a slurry, coat it on the surface of aluminum foil with a 0.02mm doctor blade, and dry to obtain a highly sodium-loving carbon-coated aluminum foil. One part of manganese oxide and 2.25 parts of iron oxide were placed in 80 parts of Tris-HCl buffer solution, and 0.4 parts of dopamine hydrochloride were added. After stirring for 24 hours, the mixture was filtered and then heated to 600℃ for 2 hours under an argon atmosphere to obtain carbon-coated metal particles. The mass ratio of biomass material to ammonium metavanadate in the solution is 10:0.3.
[0009] Example 2: This example provides a method for preparing a highly sodium-affinity carbon-coated aluminum foil, specifically including the following steps: Step 1: According to the mass ratio, 0.6 parts of silica, 0.5 parts of polymethyl methacrylate, 1.0 parts of polyacrylonitrile, and 0.4 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are extruded and pre-oxidized at 220℃ for 2 h. Then, under an argon atmosphere, the temperature is raised to 800℃ for 2 h. After etching in a 2 mol / L sodium hydroxide solution for 24 h, the nanofibers are washed with water and dried to obtain porous carbon fibers with a diameter of 121 nm. Step 2: After mixing and stirring the biomass material with zinc sulfate solution for 3 hours, pre-freeze at -60℃ for 6 hours, freeze-dry, then carbonize, and treat at 700℃ for 2 hours under argon atmosphere, then wash and dry to obtain doped biomass carbon material. Step 3: According to the mass ratio, mix 90 parts of porous carbon fiber, 10 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride, disperse them in N-methyl-2-pyrrolidone, stir evenly to obtain a slurry, coat it on the surface of aluminum foil with a 0.02mm doctor blade, and dry to obtain a highly sodium-loving carbon-coated aluminum foil. One part of manganese oxide and 6.5 parts of iron oxide were placed in 100 parts of Tris-HCl buffer solution, and 0.8 parts of dopamine hydrochloride were added. After stirring for 24 hours, the mixture was filtered and then heated to 600℃ for 3 hours under an argon atmosphere to obtain carbon-coated metal particles. The mass ratio of zinc sulfate in the biomass material and the zinc sulfate solution is 10:0.5.
[0010] Example 3: This example provides a method for preparing a highly sodium-affinity carbon-coated aluminum foil, specifically including the following steps: Step 1: According to the mass ratio, 0.4 parts of silica, 0.3 parts of polymethyl methacrylate, 0.7 parts of polyacrylonitrile, and 0.2 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 0.8 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are extruded and pre-oxidized at 200℃ for 3 h. Then, under an argon atmosphere, the temperature is raised to 750℃ for 3 h. After etching in a 2 mol / L sodium hydroxide solution for 18 h, the nanofibers are washed with water and dried to obtain porous carbon fibers with a diameter of 115 nm. Step 2: After mixing and stirring the biomass material with stannous chloride solution for 2 hours, pre-freeze at -60℃ for 8 hours, freeze-dry, then carbonize, and treat at 700℃ for 2 hours under argon atmosphere, then wash and dry to obtain doped biomass carbon material. Step 3: According to the mass ratio, mix 80 parts of porous carbon fiber, 20 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride, disperse them in N-methyl-2-pyrrolidone, stir evenly to obtain a slurry, coat it on the surface of aluminum foil with a 0.02mm doctor blade, and dry to obtain a highly sodium-loving carbon-coated aluminum foil. One part of manganese oxide and four parts of iron oxide were placed in 90 parts of Tris-HCl buffer solution, and 0.6 parts of dopamine hydrochloride were added. After stirring for 24 hours, the mixture was filtered and then heated to 600℃ for 2 hours under an argon atmosphere to obtain carbon-coated metal particles. The mass ratio of stannous chloride in the biomass material and the stannous chloride solution is 10:0.2.
[0011] Example 4: This example provides a method for preparing a highly sodium-affinity carbon-coated aluminum foil, specifically including the following steps: Step 1: According to the mass ratio, 0.55 parts of silica, 0.4 parts of polymethyl methacrylate, 0.8 parts of polyacrylonitrile, and 0.4 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are obtained by extrusion. After pre-oxidation at 220℃ for 2 h, the nanofibers are calcined at 800℃ for 4 h under an argon atmosphere. Then, the nanofibers are placed in a 2 mol / L sodium hydroxide solution and etched for 24 h. After washing and drying, porous carbon fibers with a diameter of 120 nm are obtained. Step 2: After mixing and stirring the biomass material with the metal salt solution for 3 hours, pre-freeze it at -60℃ for 6 hours, freeze-dry it, and then carbonize it. Under an argon atmosphere, heat it to 700℃ for 2 hours, wash and dry it to obtain doped biomass carbon material. The metal salt solution is composed of stannous chloride and sodium sulfate in a mass ratio of 1:1. Step 3: According to the mass ratio, 87 parts of porous carbon fiber, 13 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride are mixed and dispersed in N-methyl-2-pyrrolidone. After stirring evenly, a slurry is obtained. The slurry is coated on the surface of aluminum foil with a 0.02 mm doctor blade and dried to obtain a sodium-affinity carbon-coated aluminum foil. One part of manganese oxide and 3.5 parts of iron oxide were placed in 90 parts of Tris-HCl buffer solution, and 0.5 parts of dopamine hydrochloride were added. After stirring for 24 hours, the mixture was filtered and then heated to 600℃ for 2 hours under an argon atmosphere to obtain carbon-coated metal particles. The mass ratio of biomass material to metal salt in the metal salt solution is 10:0.4.
[0012] Example 5: This example provides a method for preparing a highly sodium-affinity carbon-coated aluminum foil, specifically including the following steps: Step 1: According to the mass ratio, 0.45 parts of silicon dioxide, 0.35 parts of polymethyl methacrylate, 0.8 parts of polyacrylonitrile, and 0.2 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are obtained by extrusion. After pre-oxidation at 220℃ for 2 h, the nanofibers are calcined at 800℃ for 4 h under an argon atmosphere. Then, the nanofibers are placed in a 2 mol / L sodium hydroxide solution and etched for 24 h. After washing and drying, porous carbon fibers with a diameter of 116 nm are obtained. Step 2: After mixing and stirring the biomass material with the metal salt solution for 3 hours, pre-freeze it at -60℃ for 6 hours, freeze-dry it, and then carbonize it. Under an argon atmosphere, heat it to 700℃ for 2 hours, wash and dry it to obtain doped biomass carbon material. The metal salt solution is composed of ammonium metavanadate and sodium sulfate in a mass ratio of 1:1. Step 3: According to the mass ratio, 87 parts of porous carbon fiber, 13 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride are mixed and dispersed in N-methyl-2-pyrrolidone. After stirring evenly, a slurry is obtained. The slurry is coated on the surface of aluminum foil with a 0.02 mm doctor blade and dried to obtain a sodium-affinity carbon-coated aluminum foil. One part of manganese oxide and 3.5 parts of iron oxide were placed in 90 parts of Tris-HCl buffer solution, and 0.5 parts of dopamine hydrochloride were added. After stirring for 24 hours, the mixture was filtered and then heated to 600℃ for 2 hours under an argon atmosphere to obtain carbon-coated metal particles. The mass ratio of biomass material to metal salt in the metal salt solution is 10:0.4.
[0013] Comparative Example 1: As a control experiment for Example 4, the difference is that only polymethyl methacrylate was used for pore creation, including the following steps: Step 1: According to the mass ratio, 0.4 parts of polymethyl methacrylate, 0.8 parts of polyacrylonitrile, and 0.4 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are obtained by extrusion. After pre-oxidation at 220℃ for 2 h, they are calcined at 800℃ for 4 h under an argon atmosphere to obtain porous carbon fibers. Step 2: After mixing and stirring the biomass material with the metal salt solution for 3 hours, pre-freeze it at -60℃ for 6 hours, freeze-dry it, and then carbonize it. Under an argon atmosphere, heat it to 700℃ for 2 hours, wash and dry it to obtain doped biomass carbon material. The metal salt solution is composed of stannous chloride and sodium sulfate in a mass ratio of 1:1. Step 3: According to the mass ratio, 87 parts of porous carbon fiber, 13 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride are mixed and dispersed in N-methyl-2-pyrrolidone. After stirring evenly, a slurry is obtained. The slurry is coated on the surface of aluminum foil with a 0.02mm scraper and dried to obtain carbon-coated aluminum foil. One part of manganese oxide and 3.5 parts of iron oxide were placed in 90 parts of Tris-HCl buffer solution, and 0.5 parts of dopamine hydrochloride were added. After stirring for 24 hours, the mixture was filtered and then heated to 600℃ for 2 hours under an argon atmosphere to obtain carbon-coated metal particles. The mass ratio of biomass material to metal salt in the metal salt solution is 10:0.4.
[0014] Comparative Example 2: As a control experiment for Example 4, the difference is that no carbon-coated metal particles were added, and the experiment included the following steps: Step 1: According to the mass ratio, 0.55 parts of silica, 0.4 parts of polymethyl methacrylate, and 0.8 parts of polyacrylonitrile are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are extruded and pre-oxidized at 220℃ for 2 h. Then, under an argon atmosphere, the temperature is raised to 800℃ for 4 h. After etching in a 2 mol / L sodium hydroxide solution for 24 h, the nanofibers are washed with water and dried to obtain porous carbon fibers with a diameter of 120 nm. Step 2: After mixing and stirring the biomass material with the metal salt solution for 3 hours, pre-freeze it at -60℃ for 6 hours, freeze-dry it, and then carbonize it. Under an argon atmosphere, heat it to 700℃ for 2 hours, wash and dry it to obtain doped biomass carbon material. The metal salt solution is composed of stannous chloride and sodium sulfate in a mass ratio of 1:1. Step 3: According to the mass ratio, 87 parts of porous carbon fiber, 13 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride are mixed and dispersed in N-methyl-2-pyrrolidone. After stirring evenly, a slurry is obtained. The slurry is coated on the surface of aluminum foil with a 0.02mm scraper and dried to obtain carbon-coated aluminum foil. The mass ratio of biomass material to metal salt in the metal salt solution is 10:0.4.
[0015] Comparative Example 3: As a control experiment for Example 4, the difference is that the biomass material was not doped, and the preparation steps included the following: Step 1: According to the mass ratio, 0.55 parts of silica, 0.4 parts of polymethyl methacrylate, 0.8 parts of polyacrylonitrile, and 0.4 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are obtained by extrusion. After pre-oxidation at 220℃ for 2 h, the nanofibers are calcined at 800℃ for 4 h under an argon atmosphere. Then, the nanofibers are placed in a 2 mol / L sodium hydroxide solution and etched for 24 h. After washing and drying, porous carbon fibers with a diameter of 120 nm are obtained. Step 2: According to the mass ratio, 87 parts of porous carbon fiber, 13 parts of biomass material and 10 parts of polyvinylidene fluoride are mixed and dispersed in N-methyl-2-pyrrolidone. After stirring evenly, a slurry is obtained. The slurry is coated on the surface of aluminum foil with a 0.02mm doctor blade and dried to obtain carbon-coated aluminum foil. One part of manganese oxide and 3.5 parts of iron oxide were placed in 90 parts of Tris-HCl buffer solution, and 0.5 parts of dopamine hydrochloride were added. After stirring for 24 hours, the mixture was filtered and carbonized at 600℃ for 2 hours under an argon atmosphere to obtain carbon-coated metal particles.
[0016] Comparative Example 4: As a control experiment for Example 4, the difference is that no manganese oxide was added to the carbon-coated metal particles, and the preparation steps included the following: Step 1: According to the mass ratio, 0.55 parts of silica, 0.4 parts of polymethyl methacrylate, 0.8 parts of polyacrylonitrile, and 0.4 parts of carbon-coated metal particles are placed in 12 parts of N,N-dimethylformamide and stirred to obtain a spinning solution. Electrospinning is performed with a feed speed of 1 mL / h, a voltage of 18 kV, and a distance of 20 cm between the needle and the collector. Nanofibers are obtained by extrusion. After pre-oxidation at 220℃ for 2 h, the nanofibers are calcined at 800℃ for 4 h under an argon atmosphere. Then, the nanofibers are placed in a 2 mol / L sodium hydroxide solution and etched for 24 h. After washing and drying, porous carbon fibers with a diameter of 120 nm are obtained. Step 2: After mixing and stirring the biomass material with the metal salt solution for 3 hours, pre-freeze it at -60℃ for 6 hours, freeze-dry it, and then carbonize it. Under an argon atmosphere, heat it to 700℃ for 2 hours, wash and dry it to obtain doped biomass carbon material. The metal salt solution is composed of stannous chloride and sodium sulfate in a mass ratio of 1:1. Step 3: According to the mass ratio, 87 parts of porous carbon fiber, 13 parts of doped biomass carbon material and 10 parts of polyvinylidene fluoride are mixed and dispersed in N-methyl-2-pyrrolidone. After stirring evenly, a slurry is obtained. The slurry is coated on the surface of aluminum foil with a 0.02mm scraper and dried to obtain carbon-coated aluminum foil. In this process, 3.5 parts of iron oxide were placed in 90 parts of Tris-HCl buffer solution, 0.5 parts of dopamine hydrochloride were added, and the mixture was stirred for 24 hours and then filtered. The mixture was then heated to 600℃ and carbonized for 2 hours under an argon atmosphere to obtain carbon-coated metal particles. The mass ratio of biomass material to metal salt in the metal salt solution is 10:0.4.
[0017] Performance testing: The carbon-coated aluminum foils prepared in Examples 1-5 and Comparative Examples 1-4 were cut into discs with a diameter of 16 mm. These discs were used as negative electrodes to form a full battery system with the NVP positive electrode. 75 μL of 1 M NaPF6 electrolyte was injected, and long-term cycling tests were conducted at 1 C and 5 C rates. The voltage window was set to 2.3 V-4.2 V. The discharge specific capacity at 1 C, the capacity retention rate after 500 cycles at 1 C, and the capacity retention rate after 1000 cycles at 5 C were recorded.
[0018] Table 1
[0019] Conclusions: In Example 4, bimetallic doping and a high metal particle content optimized sodium ion transport, promoted sodium deposition, and resulted in the best cycling stability. In Comparative Example 1, the absence of SiO2 for pore formation led to reduced capacity and increased volume expansion, resulting in a subsequent decrease in capacity retention. In Comparative Example 2, the absence of carbon-coated metal particles reduced sodium affinity sites, leading to uneven sodium deposition, reduced capacity, and decreased cycle retention. In Comparative Example 3, the lack of doping on the biomass material resulted in reduced ion channels, leading to decreased capacity and cycle retention. In Comparative Example 4, the absence of manganese oxide in the carbon-coated metal particles resulted in lower sodium affinity compared to the Mn / Fe composite, thus causing a decline in long-term cycling performance.
[0020] With sodium-ion batteries without negative electrodes as the main application scenario, a sodium-loving carbon functional modification layer is used on the surface of the metal foil as an active site to promote sodium deposition. By adjusting the raw materials of this carbon functional layer, including modifying the carbon material, adjusting the pore structure and surface properties of the carbon material, and optimizing the stability of the binder, the sodium nucleation overpotential is reduced, the sodium ion flux is made more uniform, the load capacity is increased, the cycling performance at high current density is improved, and the requirements of high energy density sodium metal batteries are met.
[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 a highly sodium-affinity carbon-coated aluminum foil, characterized in that, Includes the following steps: Step 1: Place silica, polymethyl methacrylate, polyacrylonitrile, and carbon-coated metal particles in N,N-dimethylformamide and stir to obtain a spinning solution. Obtain nanofibers by electrospinning, heat-treat, place in sodium hydroxide solution, etch, wash with water, and dry to obtain porous carbon fibers. Step 2: Mix porous carbon fibers, doped biomass carbon materials and polyvinylidene fluoride, disperse them in N-methyl-2-pyrrolidone, stir evenly to obtain a slurry, coat it on the surface of aluminum foil, and dry it to obtain a sodium-loving carbon-coated aluminum foil.
2. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The spinning solution in step 1 comprises the following components by weight: 0.4-0.6 parts silica, 0.3-0.5 parts polymethyl methacrylate, 0.7-1 parts polyacrylonitrile, 0.2-0.5 parts carbon-coated metal particles, and 10-12 parts N,N-dimethylformamide.
3. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The preparation steps of the carbon-coated metal particles are as follows: manganese oxide and iron oxide are placed in Tris-HCl buffer solution, dopamine hydrochloride is added and stirred for 24 hours, then filtered, and carbonized at 500-600℃ for 2-3 hours under argon atmosphere to obtain carbon-coated metal particles.
4. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The mass ratio of manganese oxide, iron oxide, and dopamine hydrochloride is 1:(2.2-6.8):(0.3-0.8).
5. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The electrospinning process parameters are as follows: feed speed of 0.8-1 mL / h, voltage of 15-18 kV, and distance between needle and collector of 15-20 cm.
6. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The heat treatment process parameters are as follows: after pre-oxidation at 200-220℃ for 2-3 hours, calcination is carried out at 700-800℃ for 2-4 hours under an argon atmosphere; the concentration of the sodium hydroxide solution is 2-3 mol / L, and the etching time is 18-24 hours.
7. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The mass ratio of porous carbon fiber to doped biomass carbon material in the slurry is (80-95):(5-20); the coating thickness of the slurry is 0.02-0.03 mm.
8. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The preparation steps of the doped biomass carbon material are as follows: after mixing and stirring the biomass material with a metal salt solution for 2-3 hours, pre-freezing at -50~-60℃ for 5-8 hours, freeze-drying, carbonizing, and then treating at 600-700℃ for 1-2 hours under an argon atmosphere, followed by washing and drying to obtain the doped biomass carbon material.
9. The method for preparing a highly sodium-affinity carbon-coated aluminum foil according to claim 1, characterized in that, The metal salt solution includes one or a combination of two of ammonium metavanadate, sodium sulfate, zinc sulfate, and stannous chloride; the mass ratio of the biomass material to the metal salt in the metal salt solution is 10:(0.2-0.5).
10. A highly sodium-affinity carbon-coated aluminum foil, characterized in that, Prepared by the preparation method according to any one of claims 1-9.