CN-122025558-A - Pre-lithiation method, equipment and medium for silicon-carbon composite negative electrode material of lithium ion battery

CN122025558ACN 122025558 ACN122025558 ACN 122025558ACN-122025558-A

Abstract

The invention provides a method, equipment and medium for pre-lithiation of a silicon-carbon composite negative electrode material of a lithium ion battery, and relates to the technical field of electrochemistry, comprising the steps of growing single-wall carbon nanotubes by a floating catalyst chemical vapor deposition method to obtain macroscopic three-dimensional carbon nanotube aerogel, and performing functionalization treatment on the macroscopic three-dimensional carbon nanotube aerogel to obtain functionalized three-dimensional carbon nanotube aerogel; the preparation method comprises the steps of obtaining silicon-carbon composite aerogel, obtaining a three-dimensional interconnected silicon-carbon composite negative plate, carrying out integrated pre-lithiation on the three-dimensional interconnected silicon-carbon composite negative plate, and taking the three-dimensional interconnected silicon-carbon composite negative plate after the pre-lithiation as a negative electrode material of a lithium ion battery. The technical problems of uniform, controllable and safe pre-lithiation of the silicon-carbon composite anode material which is suitable for taking a three-dimensional single-wall carbon nanotube network as a framework in the prior art are solved, and the technical effects of reducing the internal resistance of the anode material electrode of a lithium battery, improving the utilization rate of active substances and improving the pre-lithiation quality of the material are achieved.

Inventors

SONG XIAOBIN
LIU GUOHONG
LI JIANQIU

Assignees

深圳凯福新能源有限公司

Dates

Publication Date: 20260512
Application Date: 20251231

Claims (10)

1. The method for pre-lithiating the silicon-carbon composite anode material of the lithium ion battery is characterized by comprising the following steps of: Growing single-wall carbon nanotubes by a floating catalyst chemical vapor deposition method to obtain macroscopic three-dimensional carbon nanotube aerogel, and performing functionalization treatment on the macroscopic three-dimensional carbon nanotube aerogel to obtain functionalized three-dimensional carbon nanotube aerogel; Immersing the functionalized single-walled carbon nanotube aerogel into a silicon source solution, and fully immersing the pores of the functionalized single-walled carbon nanotube aerogel by a silicon source through a sol-gel method, and attaching the pores to network nodes and tube walls of the carbon nanotubes to obtain the silicon-carbon composite aerogel; Grinding the silicon-carbon composite aerogel in a protective atmosphere to obtain composite powder, mixing the composite powder, a binder and a conductive agent to prepare slurry, coating the slurry on a copper current collector, and drying to obtain a three-dimensional interconnected silicon-carbon composite negative plate; And carrying out integrated prelithiation on the three-dimensional interconnected silicon-carbon composite negative electrode plate, and taking the three-dimensional interconnected silicon-carbon composite negative electrode plate subjected to prelithiation as a negative electrode material of the lithium ion battery.
2. The method for prelithiation of the silicon-carbon composite negative electrode material of the lithium ion battery according to claim 1, wherein the macroscopic three-dimensional carbon nanotube aerogel is placed in an ozone or oxygen plasma atmosphere for mild oxidation and functionalization treatment, and the functionalized three-dimensional carbon nanotube aerogel with the surface rich in oxygen-containing functional groups is obtained.
3. The method for prelithiation of the lithium ion battery silicon-carbon composite negative electrode material according to claim 1, wherein the silicon source solution is a solution prepared by mixing ethyl orthosilicate, ethanol and water and adding ammonia water as a catalyst, and the volume concentration of the ethyl orthosilicate is 5% -20%.
4. The method for prelithiation of the silicon-carbon composite negative electrode material of the lithium ion battery according to claim 1, wherein a three-dimensional elastic interconnection network is formed between single-arm carbon nanotubes in the macroscopic three-dimensional carbon nanotube aerogel through van der waals force and winding.
5. The method for pre-lithiating a lithium ion battery silicon-carbon composite negative electrode material of claim 1, wherein the integrated pre-lithiation of the three-dimensional interconnected silicon-carbon composite negative electrode sheet, using the pre-lithiated three-dimensional interconnected silicon-carbon composite negative electrode sheet as a lithium ion battery negative electrode material, comprises: attaching a three-dimensional interconnected silicon-carbon composite negative plate to one side of a layer of solid polymer electrolyte film, and attaching the other side of the solid polymer electrolyte film to a lithium foil to generate a negative plate-electrolyte film-lithium foil laminated structure; And applying pressure and heating to the negative plate-electrolyte film-lithium foil laminated structure, performing prelithiation monitoring through a plurality of potential monitoring points deployed on the three-dimensional interconnected silicon-carbon composite negative plate, and separating and taking out the three-dimensional interconnected silicon-carbon composite negative plate after obtaining a prelithiation completion instruction to obtain the three-dimensional interconnected silicon-carbon composite negative plate after prelithiation completion.
6. The method for prelithiation of the lithium-ion battery silicon-carbon composite negative electrode material according to claim 5, wherein the negative electrode sheet-electrolyte film-lithium foil laminated structure is subjected to pressure and heating, prelithiation monitoring is performed through a plurality of potential monitoring points arranged on a three-dimensional interconnected silicon-carbon composite negative electrode, after a prelithiation completion instruction is obtained, the three-dimensional interconnected silicon-carbon composite negative electrode sheet is separated and taken out, and the three-dimensional interconnected silicon-carbon composite negative electrode sheet with prelithiation completion is obtained, and the method comprises the following steps: Collecting a plurality of open circuit potential sequences of the plurality of potential monitoring points relative to the lithium foil; traversing the open-circuit potential sequences to analyze adjacent potential change rates in the sequences to obtain a plurality of potential change rate sequences, and respectively calculating the average value of the plurality of potential change rate sequences to obtain a plurality of potential change rate average values; Global reference potential change rate identification is carried out on the average value of the potential change rates, and global reference potential change rate is determined; And carrying out temperature self-adaptive regulation and control on a plurality of potential monitoring points corresponding to the average value of the plurality of potential change rates according to the global reference potential change rate until a preset condition is met, so as to obtain a prelithiation completion instruction.
7. The method for prelithiation of the lithium-ion battery silicon-carbon composite negative electrode material of claim 6, wherein performing global reference potential change rate identification on the plurality of potential change rate averages, determining a global reference potential change rate comprises: Identifying the mode of the average value of the potential change rates to obtain an initial global reference potential change rate; Identifying bandwidth according to a preset change rate, constructing a neighborhood of the initial global reference potential change rate in the average value of the plurality of potential change rates, and obtaining the neighborhood of the initial global reference potential change rate; taking a potential change rate average value corresponding to the maximum value of the difference value from the initial global reference potential change rate neighborhood to the initial global reference potential change rate as a phase global reference potential change rate, and constructing a phase global reference potential change rate neighborhood; And comparing the neighborhood of the global reference potential change rate of the stage with the neighborhood of the initial global reference potential change rate to perform iterative identification of the global reference potential change rate, and determining the global reference potential change rate.
8. The method for prelithiation of the silicon-carbon composite negative electrode material of the lithium ion battery according to claim 7, wherein the preset condition is that the average value of the potential change rate of each of a plurality of potential monitoring points is smaller than 0.1mV/min, and the real-time open circuit potential of the plurality of potential monitoring points reaches a preset target potential range; The preset target potential range is an open-circuit potential interval corresponding to 60% -90% of theoretical capacity required to be met by the lithium ion battery anode material.
9. An electronic device, the electronic device comprising: a memory for storing executable instructions; A processor for implementing the lithium ion battery silicon-carbon composite anode material prelithiation method of any one of claims 1-8 when executing the executable instructions stored in the memory.
10. A computer readable storage medium having stored thereon a computer program, which when executed by a processor, implements a method for prelithiation of a lithium ion battery silicon-carbon composite negative electrode material as defined in any one of claims 1-8.

Description

Pre-lithiation method, equipment and medium for silicon-carbon composite negative electrode material of lithium ion battery Technical Field The invention relates to the technical field of electrochemistry, in particular to a method, equipment and medium for pre-lithiation of a silicon-carbon composite negative electrode material of a lithium ion battery. Background Increasing the energy density of lithium ion batteries is a core pursuit of the electric automobile and energy storage industry. Silicon is considered as the first choice for the next-generation anode material because of its extremely high theoretical specific capacity. However, silicon undergoes tremendous volume expansion during charge and discharge, resulting in pulverization of particles, repeated cracking and growth of the solid electrolyte interface film, loss of active material from the conductive network, and eventually rapid decay of battery capacity. The construction of silicon carbon composites is a mainstream strategy to alleviate this problem, where the carbon component (e.g. graphite, amorphous carbon, carbon nanotubes) is able to both buffer volume changes and provide electron conduction pathways. The single-wall carbon nano tube is used as a conductive additive, and has the advantages of large length-diameter ratio, excellent conductivity and high mechanical strength, so that a more effective long-range conductive network can be constructed, and the effect is better than that of the traditional carbon black, and the single-wall carbon nano tube is particularly suitable for a silicon-based negative electrode. The prior art generally combines single-walled carbon nanotubes with silicon nanoparticles, graphite, etc. by simple mechanical mixing, ball milling, or CVD coating, etc. However, these methods have significant limitations: 1. SWCNT dispersion and network construction are not ideal in that simple mixing makes it difficult to uniformly disperse SWCNTs and form a robust three-dimensional interconnected network. Under the repeated stress of silicon volume expansion/contraction, the network is easily broken and the conductive path is interrupted. 2. The pre-lithiation technology is lack that a large amount of lithium ions are consumed to form an SEI film in the first cycle of the silicon-based negative electrode, so that the irreversible capacity loss is large, and the first efficiency is low (generally < 85%). Pre-lithiation is a key technology for compensating the loss and improving the overall energy density of the battery, but how to uniformly, controllably and safely pre-lithiate a complex silicon-carbon composite material is still an industrial problem. 3. The large-scale production bottleneck is that the large-scale preparation of the high-quality SWCNT has the problems of high cost, complex process, patent barriers and the like. The process of compounding the silicon-silicon composite material is also often complicated, and mass production is difficult. Disclosure of Invention The application provides a method, equipment and medium for pre-lithiation of a silicon-carbon composite negative electrode material of a lithium ion battery, and aims to solve the technical problem that the prior art lacks a silicon-carbon composite negative electrode material which is applicable to taking a three-dimensional single-wall carbon nanotube network as a framework, and is uniform, controllable and safe for pre-lithiation of the silicon-carbon composite negative electrode material. In a first aspect of the present disclosure, a method for prelithiation of a silicon-carbon composite negative electrode material of a lithium ion battery is provided, the method comprising: The preparation method comprises the steps of growing single-walled carbon nanotubes by a floating catalyst chemical vapor deposition method to obtain macroscopic three-dimensional carbon nanotube aerogel, performing functionalization treatment on the macroscopic three-dimensional carbon nanotube aerogel to obtain functionalized three-dimensional carbon nanotube aerogel, immersing the functionalized single-walled carbon nanotube aerogel into a silicon source solution, enabling a silicon source to fully infiltrate pores of the functionalized single-walled carbon nanotube aerogel by a sol-gel method, attaching the pores of the functionalized single-walled carbon nanotube aerogel to network nodes and tube walls of the carbon nanotubes to obtain silicon carbon composite aerogel, grinding the silicon carbon composite aerogel in a protective atmosphere to obtain composite powder, mixing the composite powder, a binder and a conductive agent to prepare slurry, coating the slurry on a copper current collector, drying to obtain a three-dimensional interconnected silicon carbon composite negative plate, and performing integrated pre-lithiation on the three-dimensional interconnected silicon carbon composite negative plate after pre-lithiation to serve as a negative electrode material