Preparation method of bismuth modified coal-based carbon fiber host material of sodium metal battery
Bismuth-modified coal-based carbon fiber materials were prepared by electrospinning and carbonization processes, which solved the problem of instability of sodium anode in sodium metal batteries and achieved sodium metal batteries with high efficiency and long life.
Patent Information
- Application Number
- CN202511794804.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-02
- Publication Date
- 2026-01-20
AI Technical Summary
The high reactivity of the sodium anode in sodium metal batteries leads to the formation of an unstable solid electrolyte interface, which can easily cause sodium dendrite growth and the formation of 'dead sodium', affecting the safety and lifespan of the battery.
Bismuth-modified coal-based carbon fiber materials were prepared by electrospinning combined with a one-step carbonization process. By utilizing its porous network structure and the alloying reaction of bismuth, the sodium nucleation overpotential was reduced, sodium dendrite growth was inhibited, and the mechanical stability of the electrode was enhanced.
Stable operation of sodium metal batteries with high areal capacity and high depth of discharge was achieved, improving the cycle stability and reversibility of the batteries.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a preparation method of a bismuth-modified coal-based carbon fiber material and its use as a host for sodium metal batteries. BACKGROUND
[0002] Sodium metal batteries have the advantages of abundant resources and low cost, and are a promising large-scale energy storage technology. However, to achieve the goal of high energy density practicality, the sodium metal anode needs to be able to operate stably at high surface capacity and high discharge depth. Although the sodium metal anode has the advantages of high theoretical specific capacity and low electrode potential, its high reactivity leads to the formation of an unstable solid-state electrolyte interface on the electrode surface, which easily triggers the growth of sodium dendrites and the formation of "dead sodium", affecting the safety application and service life of sodium metal batteries.
[0003] Constructing a high-performance host material is an effective strategy to solve the above problems. The porous network structure of the three-dimensional conductive skeleton can effectively alleviate the large volume expansion of the sodium metal anode during cycling, reduce the damage to the solid-state electrolyte interface by mechanical stress, and delay the formation of dendrites by reducing the local current density, promoting the uniform deposition of sodium ions on the current collector, reducing the probability of "dead sodium" formation, and improving the cycle stability and reversibility of the battery.
[0004] Coal-based carbon materials, as a low-cost, resource-rich, and mature manufacturing process carbon source, have excellent regulation space and a wide variety of functional groups, making them an ideal candidate for high-performance current collectors. The unique porous network structure of coal-based carbon fibers and the rich oxygen-containing functional groups are of great significance in improving the sodium affinity of the material. The bismuth element, which can alloy with sodium, can significantly reduce the sodium nucleation overpotential, inhibit the growth of sodium dendrites during the cycle process, and enhance the mechanical stability and electrochemical performance of the electrode. SUMMARY
[0005] The present application aims to provide a simple and low-cost preparation method of a bismuth-modified coal-based carbon fiber material.
[0006] The present application relates to a simple and low-cost preparation method of a bismuth-modified coal-based carbon fiber host material. This method uses electrospinning combined with a one-step carbonization process to prepare a bismuth-modified coal-based carbon fiber material, which exhibits excellent electrochemical performance when used as a host material for stabilizing sodium metal anodes.
[0007] The synthesis steps include the following steps: firstly, 6.0 g of sieved coal powder is placed in a beaker, and 150 mL of mixed acid (nitric acid:sulfuric acid = 1:3) is slowly added dropwise. After acid treatment and washing, the acidified coal is dried. Secondly, polyacrylonitrile and acidified coal with a mass ratio of 3:2 are dissolved in 5 mL of N,N-dimethylformamide, and 0.2-0.4 g of bismuth acetate is added. After complete dissolution, the spinning dope is obtained. Subsequently, the spinning solution is transferred to a plastic syringe, and the voltage applied to the roller and needle is set to -1.5 kV and 11.5 kV, respectively. Finally, the injection speed is set to 0.09 mm min -1 Electrospinning is carried out. Finally, the fiber precursor is wrapped with carbon paper, and the temperature is raised to 280 ℃ at a rate of 2 ℃ min -1 in air for 2 h of pre-oxidation, and then the temperature is raised to 700-1000 ℃ at a rate of 5 ℃ min -1 under N2 for 2 h of heat preservation, to obtain bismuth-modified coal-based carbon fibers (X-CBCF, X represents different amounts of bismuth salt addition). BRIEF DESCRIPTION OF DRAWINGS
[0008] Figure 1 SEM images of bismuth-modified coal-based carbon fibers are shown. The SEM images of 0.2-CBCF ( Figure 1 a), 0.3-CBCF ( Figure 1 b) and 0.4-CBCF ( Figure 1 c) clearly show that long-range continuous and uniform structure nanofiber networks are successfully obtained by electrospinning combined with high-temperature calcination process. It is found through observation that the fibers in all samples have clear outlines, and no obvious beads are observed, which indicates that the optimized spinning process and heat treatment process effectively guarantee the integrity of the fiber morphology.
[0009] Figure 2 TGA and XRD patterns of bismuth-modified coal-based carbon fibers are shown. As shown in Figure 2 a, the bismuth element contents of 0.2-CBCF, 0.3-CBCF and 0.4-CBCF are 16.33, 20.24 and 26.72 %, respectively. The XRD pattern of X-CBCF ( Figure 2 b) shows that the modified carbon fiber material contains Bi metal and a small amount of Bi2O3, indicating that the bismuth element is successfully combined with the carbon fiber.
[0010] Figure 3 Electrochemical performance diagrams of bismuth-modified coal-based carbon fibers prepared by the present application as sodium metal host materials are shown, Figure 3 a is the coulombic efficiency diagram after assembling half-cells of different materials, and the current density is 2 mA cm -2 and the deposition surface capacity is 4 mAh cm -2Under the condition of 0.3-CBCF, the symmetrical battery can be stably cycled for more than 300 times, while 0.2-CBCF and 0.4-CBCF both have short circuit and obvious CE fluctuation in the cycle. Figure 3 b is the cycle performance of the symmetrical battery after the different material assembly, the surface capacity is 4 mAh cm -2 Under the condition of 0.3-CBCF, the symmetrical battery can be stably cycled for more than 300 times, while 0.2-CBCF and 0.4-CBCF both have short circuit and obvious CE fluctuation in the cycle. Figure 3 c is the cycle performance of the full battery, the electroplating capacity is 5 mAh cm -2 The 0.3-CBCF and NVP of sodium are assembled into a full battery, and the charging and discharging test is carried out under the current density of 10C. After 2400 times of super-long cycle, the capacity retention rate of the sample is as high as 94.34%. DETAILED DESCRIPTION
[0011] Example 1
[0012] (1) Put 6.0 g of sieved coal powder into a beaker, and slowly add 150 mL of mixed acid (nitric acid: sulfuric acid = 1:3) and distilled water in turn, fully stir, wash the precipitate to pH = 6 or so, and centrifuge and dry.
[0013] (2) 0.6 g of PAN polyacrylonitrile, 0.4 g of acidified coal and 0.2-0.4 g of bismuth acetate are dissolved in 5 mL of N,N-dimethylformamide to obtain three different spinning solutions.
[0014] (3) Transfer the spinning solution to a plastic syringe with a 19-gauge needle for electrospinning, and the voltage applied to the roller and the needle is -1.5 kV and 11.5 kV respectively, the receiving distance between the syringe and the aluminum foil is 10 cm, and the injection speed is 0.09 mm min -1 .
[0015] (4) The fiber precursor is wrapped with carbon paper, and heated to 280 ℃ at a rate of 2 ℃ min -1 in air for 2 h of pre-oxidation, and then heated to 800 ℃ at a rate of 5 ℃ min -1 under N2 for 2 h of carbonization, and naturally cooled to room temperature to obtain bismuth-modified coal-based carbon fiber (X-CBCF, X represents the addition amount of 0.2, 0.3 and 0.4 g of bismuth salt).
Claims
1. A method for preparing a bismuth-modified coal-based carbon fiber host material for a sodium metal battery, characterized by, The following steps are followed: (1) Put 6.0 g of sieved Xinjiang Heishan coal powder into a beaker, slowly add 150 mL of mixed acid (nitric acid: sulfuric acid = 1:3), and after acid treatment and washing, dry to obtain acidified coal. (2) Dissolve the acidified coal and polyacrylonitrile with a mass ratio of 3:2 in 5 mL of dimethylformamide, and then add 0.2-0.4 g of bismuth acetate, and after complete dissolution, obtain a spinning dope. (3) First, transfer the spinning solution to a plastic syringe with a 19-gauge needle, then set the voltage applied to the roller and the needle to -1.5 kV and 11.5 kV respectively, and finally set the injection speed to 0.09 mm min -1 . Perform electrospinning. (4) Wrap the fiber precursor with carbon paper, and heat to 280 ℃ at a rate of 2 ℃ min -1 in air for 2 h, and then heat to 700-1000 ℃ at a rate of 5 ℃ min -1 under N2 for 2 h, to obtain bismuth-modified coal-based carbon fiber (X-CBCF, X represents different amounts of bismuth salt added). The following steps are followed: (1) Put 6.0 g of sieved Xinjiang Heishan coal powder into a beaker, slowly add 150 mL of mixed acid (nitric acid: sulfuric acid = 1:3), and after acid treatment and washing, dry to obtain acidified coal. (2) Dissolve the acidified coal and polyacrylonitrile with a mass ratio of 3:2 in 5 mL of dimethylformamide, and then add 0.2-0.4 g of bismuth acetate, and after complete dissolution, obtain a spinning dope. (3) First, transfer the spinning solution to a plastic syringe with a 19-gauge needle, then set the voltage applied to the roller and the needle to -1.5 kV and 11.5 kV respectively, and finally set the injection speed to 0.09 mm min -1 . Perform electrospinning. (4) Wrap the fiber precursor with carbon paper, and heat to 280 ℃ at a rate of 2 ℃ min -1 in air for 2 h, and then heat to 700-1000 ℃ at a rate of 5 ℃ min -1 under N2 for 2 h, to obtain bismuth-modified coal-based carbon fiber (X-CBCF, X represents different amounts of bismuth salt added). The following steps are followed:
2. The preparation method according to claim 1, wherein the obtained bismuth-modified coal-based carbon fiber can be used as a host material for a sodium metal battery.