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CN-122025591-A - Low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and large-scale preparation method thereof

CN122025591ACN 122025591 ACN122025591 ACN 122025591ACN-122025591-A

Abstract

The invention provides a low-cost high-first-efficiency long-cycle silicon oxide carbon composite negative electrode material and a large-scale preparation method thereof, and belongs to the technical field of negative electrode materials of lithium ion batteries. The preparation method of the silicon-carbon oxide composite anode material comprises the steps of SiOx preparation, water system dispersion pulping, shell enrichment construction, spray granulation molding, high-temperature pyrolysis carbonization, post-treatment and collection, wherein the SiOx with controllable stoichiometric quantity is prepared through solid phase mechanical activation-inert atmosphere heat treatment, and the water system dispersion spray granulation and continuous carbonization are combined to construct an internal and external double-carbon coating structure, so that the large-scale preparation with low cost, high initial efficiency and long cycle performance is realized.

Inventors

  • HU ZHE
  • LI MENGLIN
  • WANG CHENCHEN

Assignees

  • 深圳大学

Dates

Publication Date
20260512
Application Date
20260211

Claims (10)

  1. 1. The low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and the large-scale preparation method thereof are characterized by comprising the following steps: Mechanically activating and mixing industrial silicon powder and silicon dioxide powder to obtain uniform mixed powder; Carrying out heat treatment on the uniform mixed powder in an inert atmosphere to obtain SiOx powder; Dispersing the SiOx powder in water, and adding conductive carbon black and a first carbon precursor to obtain uniform slurry; Adding a second carbon precursor into the uniform slurry, dispersing to obtain composite slurry, and then carrying out spray drying granulation to obtain a secondary particle composite precursor; and sequentially performing pre-oxidation stabilization and inert atmosphere carbonization on the secondary particle composite precursor to obtain the silicon oxide carbon composite anode material.
  2. 2. The low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and the large-scale preparation method thereof according to claim 1, wherein the mass ratio of the industrial silicon powder to the silicon dioxide powder is (20-60) to (80-40).
  3. 3. The low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and the large-scale preparation method thereof according to claim 1, wherein the temperature of the heat treatment is 850-1200 ℃, and the heat preservation time is 0.5-6 h.
  4. 4. The low-cost high-first-efficiency long-circulation silicon oxide carbon composite anode material and the large-scale preparation method thereof according to claim 1, wherein the addition amount of the conductive carbon black is 0.5-5% of the total mass of the SiOx powder, and the solid content of the uniform slurry is 35-55%.
  5. 5. The low-cost high-first-efficiency long-circulating silica-carbon composite anode material and the large-scale preparation method thereof according to claim 1, wherein the first carbon precursor is selected from a phenolic resin aqueous solution and/or an asphalt emulsion, and the second carbon precursor is selected from a saccharide solution and/or a low-softening-point asphalt emulsion.
  6. 6. The low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and the large-scale preparation method thereof according to claim 1, wherein the total carbon content in the composite slurry is 10-35 wt% after the second carbon precursor is added.
  7. 7. The low-cost high-first-efficiency long-circulating silicon oxide carbon composite anode material and the large-scale preparation method thereof according to claim 1, wherein the D 50 of the secondary particle composite precursor is 5-20 μm.
  8. 8. The low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and the large-scale preparation method thereof according to claim 1, wherein the pre-oxidation stabilization temperature is 200-300 ℃ and the time is 0.5-2 h; The inert atmosphere carbonization is performed in an N 2 or Ar atmosphere, the temperature is 600-1100 ℃, and the time is 1-3 hours.
  9. 9. A silicon oxide carbon composite anode material prepared by the preparation method according to any one of claims 1 to 8.
  10. 10. Use of the silicon-carbon oxide composite negative electrode material according to claim 9 for preparing a negative electrode of a lithium ion battery.

Description

Low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and large-scale preparation method thereof Technical Field The invention belongs to the technical field of lithium ion battery anode materials, and particularly relates to a low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and a large-scale preparation method thereof. Background Along with the improvement of the energy density and the cycle life requirements of the power battery and the energy storage battery, the traditional graphite cathode has limited capacity and is difficult to meet the requirement of higher energy density. Silicon oxide (SiOx, 0< x < 2) is considered as one of important candidate materials for silicon-based negative electrode industrialization because of its relatively high reversible capacity, relatively rich raw material sources and a moderation in volume effect compared with pure silicon. However, the existing SiOx materials still have obvious defects in practical application, on one hand, the SiOx is easy to form irreversible phases such as Li 2 O, lithium silicate and the like in the first-circle lithium intercalation process, and meanwhile, if the specific surface area of the material is higher, electrolyte decomposition and SEI film continuous growth are aggravated, so that the first-circle irreversible capacity loss is larger, the first-circle coulomb efficiency is lower, on the other hand, stress accumulation caused by repeated lithium intercalation and deintercalation is easy to cause particle cracking, pulverization and conductive network damage, and fresh surfaces are continuously exposed to further induce side reactions and impedance rise, so that capacity attenuation and cycle stability are insufficient. In addition, from the engineering perspective, some of the prior art adopts routes such as vacuum evaporation, vapor deposition or multiple high-temperature treatments for improving the coating or structural stability, so that the problems of large equipment investment, high energy consumption, limited productivity or long process chain exist, while other processes can reduce the cost, the processes only tend to carry out simple mechanical mixing or non-dense carbon coating, so that uneven carbon distribution, discontinuous shell layers and insufficient control of specific surface area are caused, and the problems of high first efficiency, long circulation, high compaction, low cost and ton-scale amplification are difficult to achieve. Therefore, there is a need for a method for preparing SiOx/carbon composite anode materials with low production cost, ton-level continuous preparation and good batch-to-batch consistency, which realizes high initial efficiency and long cycle performance by reducing specific surface area, constructing stable conductive/toughening structure and inhibiting interface side reaction. Disclosure of Invention In order to solve the technical problems, the invention provides a low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and a large-scale preparation method thereof, wherein industrial silicon powder and industrial silicon dioxide are used as raw materials, and solid-phase mechanical activation-inert atmosphere heat treatment is adopted to prepare SiOx with controllable stoichiometric amount; and finally, adopting a step-by-step carbon precursor introduction and shell enrichment-stabilization-carbonization densification to construct an inner carbon conductive toughness network and an outer dense carbon shell, and inhibiting electrolyte permeation and SEI overgrowth, thereby realizing high first efficiency and long cycle performance and maintaining higher reversible capacity while reducing production cost and meeting ton-level continuous production. In order to achieve the above purpose, the present invention provides the following technical solutions: the invention provides a low-cost high-first-efficiency long-cycle silicon oxide carbon composite anode material and a large-scale preparation method thereof, comprising the following steps: Mechanically activating and mixing industrial silicon powder and silicon dioxide powder to obtain uniform mixed powder; Carrying out heat treatment on the uniform mixed powder in an inert atmosphere to obtain SiOx powder; Dispersing the SiOx powder in water, and adding conductive carbon black and a first carbon precursor to obtain uniform slurry; Adding a second carbon precursor into the uniform slurry, dispersing to obtain composite slurry, and then carrying out spray drying granulation to obtain a secondary particle composite precursor; and sequentially performing pre-oxidation stabilization and inert atmosphere carbonization on the secondary particle composite precursor to obtain the silicon oxide carbon composite anode material. Further, the mass ratio of the industrial silicon powder to the silicon dioxide powder is (20-60) to (80-40), x in the