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CN-121583914-B - Carbon composite material, preparation method thereof, negative plate containing carbon composite material, electrochemical device and electronic equipment

CN121583914BCN 121583914 BCN121583914 BCN 121583914BCN-121583914-B

Abstract

The invention discloses a carbon composite material, a preparation method thereof, a negative plate containing the carbon composite material, an electrochemical device and electronic equipment. The carbon composite material comprises hard carbon and porous soft carbon, wherein the hard carbon is at least partially distributed in pores of the porous soft carbon, the carbon composite material meets the following conditions that a limiting pore specific pore volume V is 0.02cm 3 /g~0.05cm 3 /g, the limiting pore is a pore with a pore diameter of 1.5-3.2 nm, an equivalent pore average pore diameter d is 1.1-2.0 mu m, and a limiting compaction PD is 1.21-1.47. When the carbon composite material provided by the invention is applied to sodium ion batteries, the carbon composite material has excellent cycle performance and storage performance.

Inventors

  • SUN HUAYU
  • QIAN XUEFENG

Assignees

  • 远景睿泰动力技术(上海)有限公司
  • 上海交通大学

Dates

Publication Date
20260512
Application Date
20260121

Claims (10)

  1. 1. A carbon composite material, characterized in that it comprises hard carbon and porous soft carbon, said hard carbon being at least partially distributed inside the pores of said porous soft carbon; the carbon composite material satisfies the following conditions: Limiting the specific pore volume V to be 0.02 cm 3 /g ~0.05 cm 3 /g, wherein the limiting pores refer to pores with the pore diameter of 1.5-3.2 nm; the average pore diameter d of the equivalent pores is 1.1-2.0 mu m; the limit pressure PD is 1.21-1.47; The preparation method of the carbon composite material comprises the following steps: s1, calcining and crushing a mixture containing raw material coal and a pore-forming agent to obtain a soft carbon precursor, wherein the mass ratio of the raw material coal to the pore-forming agent is (2-4) 1; S2, performing heat treatment on the mixture containing the soft carbon precursor and the hard carbon source, and then cooling to obtain the carbon composite material.
  2. 2. The carbon composite of claim 1, wherein the carbon composite satisfies one or more of the following conditions a-e: a. the mass of the hard carbon accounts for 0-28% of the mass of the carbon composite material, but is not 0; b. The mass of the porous soft carbon accounts for 72-100% of the mass of the carbon composite material, and is not 100%; c. The specific pore volume V of the limiting pore is 0.023cm 3 /g~0.042cm 3 /g; d. the average pore diameter d of the equivalent pores is 1.5-1.9 mu m; e. The limit pressure PD is 1.25-1.35.
  3. 3. A method of producing the carbon composite material according to claim 1 or 2, comprising the steps of: s1, calcining and crushing a mixture containing raw material coal and a pore-forming agent to obtain a soft carbon precursor, wherein the mass ratio of the raw material coal to the pore-forming agent is (2-4) 1; S2, performing heat treatment on the mixture containing the soft carbon precursor and the hard carbon source, and then cooling to obtain the carbon composite material.
  4. 4. A method of producing a carbon composite material according to claim 3, wherein the method of producing a carbon composite material satisfies one or more of the following conditions a to d: a. In the step S1, the mass ratio of the raw material coal to the pore-forming agent is (3-4): 1; b. In the step S1, the raw material coal is brown coal; c. In the step S1, the pore-forming agent is sodium salt and/or potassium salt, and the pore-forming agent comprises one or more of Fe, mn, ni and Co elements; d. In the step S1, the particle diameter Dv50 of the soft carbon precursor is 4-6.5 μm.
  5. 5. A method of producing a carbon composite material according to claim 3, wherein the method of producing a carbon composite material satisfies one or more of the following conditions a to e: a. In the step S1, the raw material coal is firstly subjected to impurity removal before calcination, wherein the impurity removal mode is to co-burn the raw material coal and strong alkali, and then rinse the raw material coal and the strong alkali, wherein the mass ratio of the raw material coal to the strong alkali is (1-3): 1; b. in the step S1, the calcining temperature is 200-1000 ℃; c. in the step S1, the calcination time is 8-10 hours; d. In the step S1, the calcination is divided into a first calcination, a second calcination and a third calcination, wherein the temperature of the first calcination is 200-300 ℃, the time of the first calcination is 1-3 hours, the temperature of the second calcination is 400-500 ℃, the time of the second calcination is 1-3 hours, the temperature rising rate of the second calcination is 1-3 ℃ per minute, the temperature of the third calcination is 700-900 ℃, and the time of the third calcination is 4-6 hours; e. in the step S1, the temperature rising rate of calcination is 2-4 ℃.
  6. 6. The method for producing a carbon composite material according to claim 3, wherein the method for producing a carbon composite material satisfies one or more of the following conditions a to g: a. in the step S2, the hard carbon source is asphalt and/or phenolic resin, and the softening point of the asphalt is less than or equal to 90 ℃; b. In the step S2, the coking value of the hard carbon source is 15% -36%; c. in the step S2, the mass ratio of the hard carbon source to the soft carbon precursor is (1-3) 1; d. In the step S2, the temperature of the heat treatment is 700-1000 ℃; e. in the step S2, the time of the heat treatment is 4-6 hours; f. In the step S2, the cooling mode is natural cooling and/or nitrogen cooling; g. In step S2, prior to the heat treatment, a pre-cure is also performed, said pre-cure comprising three stages: the pre-curing temperature in the first stage is 100-130 ℃, and the pre-curing time is 2 hours; The pre-curing temperature of the second stage is 130-180 ℃, the pre-curing time is 2 hours, and the pre-curing pressure is 0.2-0.8 mpa; the pre-curing temperature in the third stage is 250-320 ℃, the pre-curing time is 2 hours, and the pre-curing pressure is 1.5-2.5 mpa.
  7. 7. A method of producing a carbon composite material according to claim 3, wherein in step S2, mechanical fusion is further performed on the cooled product, the mechanical fusion satisfying one or more of the following conditions a to c: a. the frequency of the mechanical fusion is 7000-9000 Hz; b. the power of the mechanical fusion is 120-160 KW; c. the mechanical fusion time is 2-4 hours.
  8. 8. A negative electrode sheet, characterized in that it comprises the carbon composite material according to claim 1 or 2.
  9. 9. An electrochemical device comprising the carbon composite material according to claim 1 or 2 or the negative electrode sheet according to claim 8.
  10. 10. An electronic device characterized in that it comprises the electrochemical device according to claim 9.

Description

Carbon composite material, preparation method thereof, negative plate containing carbon composite material, electrochemical device and electronic equipment Technical Field The invention relates to a carbon composite material, a preparation method thereof, a negative plate containing the carbon composite material, an electrochemical device and electronic equipment. Background Due to the high energy density of sodium ion batteries (e.g., large cylindrical sodium ion batteries), the potential for use in the energy storage field is being explored, but the energy storage system requires very high long cycle performance, which tends to place higher demands on the negative electrode materials. Because the hard carbon is widely available, the hard carbon is used as a negative electrode material, and has the characteristics of high specific capacity, good structural stability and good low-temperature performance of the battery, but the defects of low first charge and discharge efficiency, poor cycle stability and limited storage performance are also present. CN117810447a improves pore distribution by phosphorus doping, optimizing cycle performance. CN120504319a effectively improves morphology, improves storage, but to a limited extent, by optimizing the precursor. Therefore, how to improve the initial efficiency, cycle performance and storage performance of a battery when hard carbon is used as a negative electrode material has been receiving much attention in the art. Disclosure of Invention The invention mainly aims to overcome the defects of insufficient initial effect, cycle performance and storage performance of a battery when hard carbon is used as a negative electrode material in the prior art, and provides a carbon composite material, a preparation method thereof, a negative electrode plate containing the carbon composite material, an electrochemical device and electronic equipment. When the carbon composite material provided by the invention is applied to a sodium ion battery, the carbon composite material has excellent initial effect, cycle performance and storage performance. In a first aspect, the present invention provides a carbon composite comprising hard carbon and porous soft carbon, the hard carbon being at least partially distributed within the pores of the porous soft carbon; the carbon composite material satisfies the following conditions: Limiting the specific pore volume V to be 0.02cm 3/g~0.05cm3/g, wherein the limiting pores refer to pores with the pore diameter of 1.5-3.2 nm; the average pore diameter d of the equivalent pores is 1.1-2.0 mu m; the limit pressure PD is 1.21-1.47. In a second aspect, the present invention provides a method for preparing the carbon composite material, comprising the steps of: s1, calcining and crushing a mixture containing raw material coal and a pore-forming agent to obtain a soft carbon precursor, wherein the mass ratio of the raw material coal to the pore-forming agent is (2-4) 1; S2, performing heat treatment on the mixture containing the soft carbon precursor and the hard carbon source, and then cooling to obtain the carbon composite material. In a third aspect, the present invention provides a negative electrode sheet comprising a carbon composite material as described above. In a fourth aspect, the present invention provides an electrochemical device comprising a carbon composite as described above or a negative electrode sheet as described above. In a fifth aspect, the present invention provides an electronic device comprising an electrochemical apparatus as described above. On the basis of conforming to the common knowledge in the field, the above preferred conditions can be arbitrarily combined to obtain the preferred examples of the invention. The reagents and materials used in the present invention are commercially available. The invention has the positive progress effects that: The carbon composite material provided by the invention has specific limiting pore volume, equivalent pore average pore diameter and extreme compaction, and when the carbon composite material is applied to a sodium ion battery, the battery has excellent initial efficiency, cycle performance and storage performance. Detailed Description Carbon composite material In a first aspect of the present invention there is provided a carbon composite comprising hard carbon and porous soft carbon, the hard carbon being at least partially distributed within the pores of the porous soft carbon; the carbon composite material satisfies the following conditions: Limiting the specific pore volume V to be 0.02cm 3/g~0.05cm3/g, wherein the limiting pores refer to pores with the pore diameter of 1.5-3.2 nm; the average pore diameter d of the equivalent pores is 1.1-2.0 mu m; the limit pressure PD is 1.21-1.47. In the invention, the carbon composite material is a composite material formed by hard carbon and soft carbon, namely, a single particle comprises a hard carbon part and a soft carbon par