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CN-116924387-B - Modified hard carbon material and preparation method and application thereof

CN116924387BCN 116924387 BCN116924387 BCN 116924387BCN-116924387-B

Abstract

The invention discloses a modified hard carbon material, a preparation method and application thereof, wherein the preparation method comprises the following steps of S1, heating and preserving heat of biomass hard carbon in an aerobic environment to obtain oxygen-doped biomass hard carbon, wherein the heating temperature is 250-350 ℃, the heating rate is 2-5 ℃ per minute, the preserving heat time is 2-5 h, S2, protective atmosphere is introduced in advance before S1 is finished, heating and preserving heat are carried out to obtain stabilized biomass hard carbon, the heating temperature is 400-800 ℃, the heating rate is 2-10 ℃ per minute, the preserving heat time is 0.5-2.5 h, and S3, and the biomass hard carbon after S2 treatment is heated and preserved in the protective atmosphere. The invention combines the oxygen doping treatment and the stabilization process of the biological hard carbon, and rearranges the carbon layer at high temperature to obtain the hard carbon material, which can improve the carbon yield, has no impurity and has the advantages of high primary charging capacity and high primary efficiency.

Inventors

  • WU JUN
  • WANG GUANGJIN
  • ZHANG HUAYU
  • MO ZHIBO
  • WU YUNQI
  • XU SHAOXIA
  • Li Moheng

Assignees

  • 四川易纳能新能源科技有限公司

Dates

Publication Date
20260505
Application Date
20230728

Claims (9)

  1. 1. The preparation method of the modified hard carbon material is characterized by comprising the following steps of: S1, heating and preserving heat of biomass hard carbon in an aerobic environment to obtain oxygen-doped biomass hard carbon, wherein the heating temperature is 250-350 ℃, the heating rate is 2-5 ℃ per minute, and the preserving heat time is 2-5 hours; S2, introducing protective atmosphere in advance before the S1 is finished, heating and preserving heat to obtain stabilized biomass hard carbon, wherein the heating temperature is 400-800 ℃, the heating rate is 2-10 ℃ per minute, and the preserving heat time is 0.5-2.5 h; And S3, heating the biomass hard carbon treated by the S2 in a protective atmosphere, and then preserving heat, wherein the condition of preserving heat after heating is that the heating temperature is 1300-1400 ℃, the heating rate is 2-5 ℃ per minute, and the preserving heat time is 3 hours.
  2. 2. The method of claim 1, wherein the biomass hard char in S1 is cellulose-based biomass hard char or nut shells.
  3. 3. The preparation method of the heat insulation material according to claim 1, wherein the heating and heat insulation conditions in the step S1 are that the heating temperature is 280 ℃, the heating rate is 5 ℃ per minute, and the heat insulation time is 4-5 hours.
  4. 4. The preparation method according to claim 1, wherein the heating and heat preservation conditions in the step S2 are that the heating temperature is 400 ℃, the heating rate is 5 ℃ per minute, and the heat preservation time is 1 h.
  5. 5. The method according to claim 1, wherein the stabilized biomass hard char obtained in S2 is ball milled and screened to obtain a screened material, and then subjected to S3 treatment.
  6. 6. The preparation method according to claim 1, wherein the biomass hard char in S1 is nut shells, the stabilized biomass hard char obtained in S2 is ball milled and screened, and the screened material is soaked in hydrochloric acid solution, then washed to be neutral, and dried and then subjected to the S3 treatment.
  7. 7. The method according to claim 1, wherein the protective atmosphere in S2 and S3 is one selected from the group consisting of nitrogen, argon, helium, neon, krypton, xenon, and radon.
  8. 8. A modified hard carbon material obtained by the production method according to any one of claims 1 to 7.
  9. 9. Use of the modified hard carbon material of claim 8 in the preparation of a negative electrode material for sodium ion batteries.

Description

Modified hard carbon material and preparation method and application thereof Technical Field The invention relates to the technical field of battery cathode materials, in particular to a modified hard carbon material, a preparation method and application thereof. Background With the research heat of sodium ion batteries for several years, the traditional graphite material cannot form stable intercalation compounds with sodium ions, the maximum metering ratio of sodium in graphite is only NaCl 86 or NaC 64, the capacity is only 12 mah/g or 36 mah/g, the development requirement of the sodium ion battery cannot be met at all, although the capacity and first effect can be improved through ether electrolyte, the cost of the ether electrolyte is high, and the gram capacity is only less than 150mah/g, so that the sodium ion battery is also a cup-water salary for sodium battery development. Hard carbon has a large interlayer spacing, a complex and changeable structure and a large number of sodium ion storage active sites, so that the hard carbon becomes a first-choice anode material for future commercial application of sodium batteries. The hard carbon is widely available from the aspects of surrounding environment, can be mainly divided into three types of resin, asphalt and biomass, is limited by cost and development process difficulty, and the current commercial hard carbon mainly comprises biomass hard carbon which has the advantages of high capacity and low cost, and is a preparation route of the current mainstream hard carbon. However, the carbon yield of the biomass hard carbon from the precursor to the finished product is less than 20%, and how to improve the carbon yield of the biomass hard carbon is a problem to be solved in the current industry. In the prior art, bamboo charcoal or anthracite is used as a hard carbon substrate material, and soft carbon material is introduced, so that the carbon production rate can be greatly improved, but the mode can not only remarkably reduce the first effect or capacity and other electrochemical properties of biomass charcoal, but also introduce impurity elements contained in the soft carbon into the product. Therefore, how to improve the carbon yield of the biomass hard carbon and the electrochemical performance at the same time without introducing foreign elements is a key problem facing the current biomass hard carbon preparation field for a long time. Disclosure of Invention Aiming at the current development situation that the traditional biomass hard carbon is low in carbon yield, and the soft carbon is used for coating the biomass hard carbon to a certain extent, but the initial efficiency is low and the capacity is low, the inventor creatively provides a modified hard carbon material and a preparation method and application thereof on the premise that the soft carbon material is not introduced. Specifically, in order to achieve the above purpose, the present invention adopts the following technical scheme: In a first aspect, the present invention provides a method for preparing a modified hard carbon material, comprising the steps of: S1, heating and preserving heat of biomass hard carbon in an aerobic environment to obtain oxygen-doped biomass hard carbon, wherein the heating temperature is 250-350 ℃, the heating rate is 2-5 ℃ per minute, and the preserving heat time is 2-5 hours; S2, introducing protective atmosphere in advance before the S1 is finished, heating and preserving heat to obtain the stabilized biological hard carbon, wherein the heating temperature is 400-800 ℃, the heating rate is 2-10 ℃ per minute, and the preserving heat time is 0.5-2.5 h; S3, heating the biomass hard carbon treated by the S2 in a protective atmosphere, and then preserving heat. Preferably, the biochar in S1 is cellulose-based biomass charcoal or nut shells. The cellulose is one or more selected from microcrystalline cellulose, food cellulose, multi-polymer cellulose, lignocellulose, cellulose ether, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose, and the nut shell is one or more selected from pecan shell, walnut shell, almond shell, hazelnut shell, peanut shell, acorn, apricot shell, hawaii shell and pistachio shell. In some embodiments of the present invention, the cellulose is microcrystalline cellulose or food cellulose, but not limiting the present invention, the preparation method of the present invention may be applied not only to microcrystalline cellulose hard carbon, but also to biomass materials containing cellulose-based precursors, and even most biomass materials may achieve the same effect. In some embodiments of the present invention, the biomass hard char in S1 is pecan shell, but not limiting the present invention, other nut shells of the present invention may achieve the same effect. Preferably, the heating and heat preservation conditions in the step S1 are that the heating temperature is 280 ℃, the heati