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CN-121983574-A - Hard carbon material and preparation method and application thereof

CN121983574ACN 121983574 ACN121983574 ACN 121983574ACN-121983574-A

Abstract

The invention provides a hard carbon material, a preparation method and application thereof, wherein the hard carbon material consists of a three-dimensional carbon layer, micropores and closed holes are formed in the three-dimensional carbon layer, defective structures are distributed at the interfaces of the micropores and the closed holes and the three-dimensional carbon layer, and the I D /I G of the hard carbon material is 1.105-1.286. The hard carbon material provided by the invention is a biomass derived hard carbon material with cooperative regulation and control of interlayer spacing, a closed cell structure and defect distribution, realizes cooperative controllability of closed cell size, closed cell volume and microcrystalline disorder degree, and further gives consideration to high platform capacity, higher ICE and excellent multiplying power performance.

Inventors

  • LI YONGLI
  • DU RUIJIE
  • WANG JUN
  • ZHOU DONG
  • Ni Jialun
  • Ning De
  • LIU XUELING

Assignees

  • 华北电力大学

Dates

Publication Date
20260505
Application Date
20260202

Claims (10)

  1. 1. The hard carbon material is characterized by comprising a three-dimensional carbon layer, wherein micropores and closed holes are formed in the three-dimensional carbon layer, defective structures are distributed at the interfaces of the micropores and the closed holes and the three-dimensional carbon layer, and the I D /I G of the hard carbon material is 1.105-1.286.
  2. 2. The hard carbon material according to claim 1, wherein the pore size of the micropores is <2nm, and the pore size of the closed pores is 2nm to 5nm; preferably, the closed cells have a cell volume of 0.05cm 3 g -1 ~0.09cm 3 g -1 ; preferably, the interlayer distance d (002) of the carbon layer is 0.376 nm-0.387 nm; preferably, the defect structure comprises an sp3-sp2 mixed boundary defect and an oxygen vacancy control defect.
  3. 3. A method for producing the hard carbon material according to claim 1 or 2, comprising: (1) Mixing ethyl acetate, hydrogen peroxide and a catalyst to obtain a treatment fluid, and mixing a biomass material with the treatment fluid to perform an in-situ oxidation reaction; (2) And (3) sequentially pre-carbonizing and carbonizing the product obtained after the in-situ oxidation reaction in the step (1) to obtain the hard carbon material.
  4. 4. A method of preparation according to claim 3, wherein the catalyst of step (1) comprises sulfuric acid; preferably, the mass concentration of the hydrogen peroxide in the step (1) is 13-18 wt%; preferably, the volume ratio of the ethyl acetate to the hydrogen peroxide in the step (1) is 1 (1-3); Preferably, the mass ratio of the catalyst in the step (1) in the treatment liquid is 0.8-1.2 wt%; preferably, the mass ratio of the biomass material to the treatment fluid in the step (1) is 1g (18-22) mL; preferably, the biomass material of step (1) comprises a plant-based biomass material.
  5. 5. The method according to claim 3 or 4, wherein the in-situ oxidation reaction in step (1) is carried out at a temperature of 50 ℃ to 80 ℃; preferably, the time of the in-situ oxidation reaction in the step (1) is 12-20 hours; Preferably, the product after the in-situ oxidation reaction in step (1) is washed and dried sequentially.
  6. 6. The method according to any one of claims 3 to 5, wherein the product after the in-situ oxidation reaction is subjected to a pulverization treatment before the pre-carbonization in step (2); Preferably, the temperature rising rate of the pre-carbonization in the step (2) is 4-6 ℃ per hour; Preferably, the cut-off temperature of the pre-carbonization in the step (2) is 350-450 ℃, and the heat preservation time is 2-4 hours.
  7. 7. The method according to any one of claims 3 to 6, wherein after the pre-carbonization in step (2), the pre-carbonized product is subjected to acid washing; Preferably, the agent for pickling comprises hydrochloric acid; preferably, the concentration of the hydrochloric acid is 0.8 mol/L-1.2 mol/L; Preferably, the pickling time is 3-5 hours; Preferably, after the pickling is finished, the product is washed and dried sequentially.
  8. 8. The method according to any one of claims 3 to 7, wherein the carbonization in step (2) has a temperature rise rate of 4 ℃ to 6 ℃ per hour; Preferably, the carbonization cut-off temperature in the step (2) is 1200-1400 ℃, and the heat preservation time is 1-3 h.
  9. 9. A negative electrode sheet, characterized in that the negative electrode sheet comprises the hard carbon material according to claim 1 or 2 or a hard carbon material produced by the production method according to any one of claims 3 to 8.
  10. 10. A sodium ion battery comprising the negative electrode tab of claim 9.

Description

Hard carbon material and preparation method and application thereof Technical Field The invention belongs to the technical field of secondary battery anode materials, and relates to a hard carbon material, a preparation method and application thereof. Background Sodium-Ion batteries (SIBs) are considered to be a powerful complement to lithium-Ion batteries because of their abundant Sodium resources and low cost. Hard carbon is used as one of the main current anode materials of the SIB, has high reversible capacity, good multiplying power performance and low cost, and is one of key materials for promoting the commercialization of the SIB. Biomass-derived hard carbon is a major direction in the preparation of hard carbon in its renewable, low cost and naturally porous/anisotropic precursor structure. Currently, the methods for preparing hard carbon from biomass feedstock mainly include the following: 1. Pretreating and carbonizing exogenous peracetic acid (PAA) or other strong oxidants, (1) immersing biomass raw materials (such as lignocellulose, bamboo powder, fruit shells and the like) in an externally prepared peracetic acid solution or an H 2O2/acetic acid mixed system according to a proper solid-to-liquid ratio, (2) reacting for a certain time under room temperature or mild heating conditions to realize oxidization/delignification, (3) filtering, washing, neutralizing and drying, and (4) carbonizing under an inert atmosphere according to a preset temperature program to obtain a hard carbon sample. 2. Carbonization after alkali activation to produce a high specific surface area and porous structure by mixing/impregnating biomass with KOH in proportion, drying, carbonizing at high temperature under an inert atmosphere, and then removing residual alkali metal by acid washing to obtain activated carbon. 3. Enzymatic or biological processes to selectively degrade lignin/hemicellulose followed by carbonization by treatment of the biomass with lignin degrading enzymes (e.g., laccase/peroxidase) or cellulases under mild conditions to selectively remove or reconstruct the woody components, followed by drying and carbonization to give hard carbon. However, the hard carbon obtained by the method or the method still has the following problems that 1. The pore structure is uncontrollable, the closed pore is insufficient, the existing biomass hard carbon is prepared by adopting direct pyrolysis or chemical activation (KOH, znCl 2 and the like), so that the pore structure is difficult to regulate and control, and especially the ratio of the closed pore to the micropore is unreasonable, so that the filling behavior of sodium ions on a low-potential platform is not facilitated. 2. The interlayer spacing is smaller, sodium ion diffusion is limited, the interlayer spacing is often less than 0.37nm after traditional biomass carbonization, na + can not be effectively promoted to be embedded between layers, and the platform capacity is low and dynamics is slow. 3. The defect structure is disordered, the active sites are insufficient, the defect type and distribution of the carbon structure are lack of control by a common pyrolysis process, the density of the active sites (such as edge carbon and heteroatom doping sites) is low, and the adsorption/filling sodium storage capacity and the electrochemical stability are affected. 4. The surface functional group is complex, the initial coulomb efficiency is low, active groups such as carboxyl, hydroxyl, aldehyde group and the like are contained in biomass, the active groups are not effectively passivated or selectively decomposed, and the carbonized surface is easy to have side reaction with electrolyte, so that the Initial Coulomb Efficiency (ICE) is low. 5. The acid/alkali treatment method has side effects, and the traditional acid leaching modification (such as H 2SO4 and HCl) can remove impurities and adjust the structure to a certain extent, but is easy to cause excessive damage to a biomass skeleton or introduce excessive hetero functional groups, so that the subsequent carbonization is not facilitated to form a stable structure. Alkali activation (KOH, naOH) may introduce metal residues or cause structural collapse. 6. The method has the advantages of high energy consumption, complex process steps and heavy environmental burden, and the existing multi-step chemical modification and high-temperature activation processes have high energy consumption and large chemical reagent consumption, and do not meet the requirement of green sustainable development. In addition, the pretreatment of exogenous PAA or strong oxidant can change lignin components, but has the problems of safety, peroxidation and insufficient selectivity, the alkali activation can greatly improve pore volume and specific surface area, but mainly produce open pores and damage ICE and structural stability, and the enzymolysis method and DES can regulate precursor microstructure more gently/accurately, but have pra