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CN-122025600-A - High-entropy alloy composite carbon fiber negative electrode material for lithium ion battery and preparation method thereof

CN122025600ACN 122025600 ACN122025600 ACN 122025600ACN-122025600-A

Abstract

The invention relates to the technical field of lithium ion battery cathode materials, in particular to a high-entropy alloy composite carbon fiber cathode material for a lithium ion battery and a preparation method thereof. The electrical performance of the composite material formed by the high-entropy alloy and the carbon nano fiber designed in the equimolar ratio or near equimolar ratio needs to be further improved. Aiming at the problems, the invention provides a high-entropy alloy composite carbon fiber negative electrode material for a lithium ion battery, which is an electrode material formed by compositing five or seven metal elements according to a non-equimolar ratio or a near molar ratio, and the high-entropy alloy composite carbon fiber negative electrode material can effectively enhance the lithium storage capacity of the material by reasonably increasing the proportion of elements with higher electrochemical activity, fully exert the synergistic effect among multiple principal elements, avoid the problem of active dilution caused by 'average sense', and remarkably improve the reversible capacity and the cycling stability of the composite negative electrode material.

Inventors

  • REN YURONG
  • WU CHAOJUN
  • LI JIANBIN

Assignees

  • 常州大学

Dates

Publication Date
20260512
Application Date
20260318

Claims (10)

  1. 1. The high-entropy alloy composite carbon fiber negative electrode material for the lithium ion battery is characterized by being an electrode material formed by compositing carbon nanofibers with a high-entropy alloy formed by five or seven metal elements, wherein the high-entropy alloy in the electrode material is composed of Fe, co, cu, ni, zn or Fe, co, cu, ni, in or Fe, co, cu, ni, zn, mn, in according to a molar ratio of 5:1:1:1:1:1, 5:1:1:1:1:1 and 4:1:1:1:1:1:1 respectively.
  2. 2. The high-entropy alloy composite carbon fiber negative electrode material for lithium ion batteries according to claim 1, wherein the preparation method comprises the following steps: (1) Adding soluble metal salt corresponding to the high-entropy alloy into an organic solvent to form uniform metal precursor dispersion; (2) Adding high-temperature carbonized high-molecular polymer precursors for forming carbon nanofibers into the metal precursor dispersion liquid to form uniform spinning solution; (3) Carrying out electrostatic spinning on the spinning solution by an electrostatic spinning method, and forming a nanofiber membrane on the surface of the collecting plate; (4) And sequentially performing stability heat treatment in air and high-temperature carbonization under inert gas on the nanofiber membrane to obtain the high-entropy alloy composite carbon fiber anode material.
  3. 3. The high-entropy alloy composite carbon fiber negative electrode material for lithium ion batteries according to claim 2, wherein the soluble metal salt is Fe, co, cu, ni, zn, mn, in acetate.
  4. 4. The high-entropy alloy composite carbon fiber negative electrode material for lithium ion batteries according to claim 2, wherein the organic solvent comprises one or more of N, N-dimethylformamide, N-dimethylacetamide, tetrahydrofuran, dimethylacetamide, acetone, isopropanol, hexafluoroisopropanol and absolute ethanol.
  5. 5. The high-entropy alloy composite carbon fiber negative electrode material for lithium ion batteries according to claim 2, wherein the high-molecular polymer precursor is polyacrylonitrile, and the average molecular weight mw=150000-500000.
  6. 6. The high-entropy alloy composite carbon fiber negative electrode material for lithium ion batteries according to claim 2, wherein the molar mass ratio of the total molar amount of the soluble metal salt corresponding to the high-entropy alloy to the high-molecular polymer precursor is 1 mmol/1 g.
  7. 7. The high-entropy alloy composite carbon fiber anode material for lithium ion batteries according to claim 2, wherein, In the electrostatic spinning process, a spinning needle head is 21 types, a collecting plate for electrostatic spinning is arranged at a position 10-15 cm away from the needle head, the working voltage of a high-voltage power supply is set to be 15-18 kV, and the flow rate of a propeller is set to be 0.5-0.8 mL h -1 .
  8. 8. The high-entropy alloy composite carbon fiber negative electrode material for lithium ion batteries according to claim 2, wherein the stability heat treatment is to heat up a nanofiber membrane to 200-220 ℃ in air in a blast drier and preserve heat for 3-4 hours, and the heating rate is not lower than 20 ℃ min -1 .
  9. 9. The high-entropy alloy composite carbon fiber negative electrode material for lithium ion batteries according to claim 2, wherein the high-temperature carbonization is to transfer the nanofiber membrane subjected to the stability heat treatment into a tube furnace, raise the temperature to 900 ℃ under the protection of inert atmosphere and keep the temperature for 2-3 hours.
  10. 10. The negative electrode plate for a lithium ion battery is characterized in that the high-entropy alloy composite carbon fiber negative electrode material for the lithium ion battery as a negative electrode active substance is uniformly mixed with a binder, a conductive agent and a solvent respectively, then uniformly coated on the surface of a negative electrode current collector, and finally dried and compacted in sequence to form the electrode plate.

Description

High-entropy alloy composite carbon fiber negative electrode material for lithium ion battery and preparation method thereof Technical Field The invention relates to the technical field of lithium ion battery cathode materials, in particular to a high-entropy alloy composite carbon fiber cathode material for a lithium ion battery and a preparation method thereof. Background Lithium ion batteries have become a core power source for portable electronic devices, electric vehicles and large-scale energy storage systems due to the advantages of high energy density, long cycle life, environmental friendliness and the like. The negative electrode material is used as a key component of the lithium ion battery, and the performance of the negative electrode material directly influences the overall electrochemical performance of the battery. At present, a commercial lithium ion battery mainly adopts a graphite carbon material as a negative electrode, but has lower theoretical specific capacity (372 mAh g < -1 >) and limited multiplying power performance, and is difficult to meet the development requirements of high-energy-density and high-power-density energy storage devices. Therefore, the development of novel high-capacity, long-cycle-life anode materials is a current research hotspot. The high-entropy alloy is used as a novel metal alloy material, breaks through the design concept that the traditional alloy takes a single element as a principal element, and consists of five or more principal element elements in nearly equimolar ratio. Due to the unique high entropy effect, lattice distortion effect and delayed diffusion effect, the high entropy alloy has excellent mechanical property, corrosion resistance and electrochemical stability, and has wide application prospect in the field of lithium ion battery cathode materials. In particular, the high-entropy alloy is compounded with the carbon material, so that the high-capacity advantage of the high-entropy alloy can be exerted, and the volume expansion effect in the alloying reaction process can be relieved by utilizing the conductivity and the buffer effect of the carbon material, so that the cycling stability of the electrode is improved. At present, the high-entropy alloy and the composite anode material thereof are researched, and the component design mostly follows the traditional thinking of equimolar ratio or nearly equimolar ratio (for example, chinese patent invention CN 118389966A), namely, the atomic percentages of all principal elements tend to be equal or nearly equal. While this design concept helps to maximize the configurational entropy to obtain a stable solid solution structure, there are the following disadvantages in specific applications facing lithium ion battery cathodes: First, equimolar ratio designs are difficult to orient optimize for electrochemical performance. In a high-entropy alloy system, the storage activity, the reaction potential and the catalytic activity of different metal elements on lithium ions are obviously different. If simply mixed in equimolar ratios, it may result in too high a fraction of the electrochemically less active component, diluting the active sites, thereby limiting further enhancement of the reversible capacity of the material. In other words, such "average sense" component designs fail to fully exert synergistic effects among multiple principals and fail to maximize capacity. Second, the introduction of a portion of the elements at equimolar ratios may adversely affect the cycling stability. For example, some elements with a large volume expansion rate in the alloying reaction (such as Zn, mn, etc. in some studies) may accelerate pulverization of the electrode structure if they occupy too high a proportion in an equimolar ratio system, and their drastic volume change during charge and discharge may occur. Meanwhile, not all the elements can be uniformly distributed in the carbon fiber matrix in an equimolar ratio, and partial element segregation may induce side reactions, so that a solid electrolyte interface film (SEI film) is unstable and finally reflected as rapid decay of circulation capacity. Furthermore, the design concept of equimolar ratio limits the screening range of high-performance high-entropy alloy systems. Limited to the framework of "five and more principal components and similar proportions," researchers often ignore the "cocktail effect" that non-equimolar combinations may bring. In fact, by controlling the non-stoichiometric ratio of each element, the electronic structure, the degree of lattice distortion and the free energy of reaction with lithium ions of the alloy can be modulated more flexibly, so that the comprehensive electrochemical performance which is more excellent than the combination of equimolar ratio is expected to be obtained. Therefore, how to break the design formulation of the traditional equimolar ratio, fully exert the synergistic effect of specific element combination t