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CN-121990569-A - Graphene/activated carbon composite material and preparation method and application thereof

CN121990569ACN 121990569 ACN121990569 ACN 121990569ACN-121990569-A

Abstract

The invention provides a graphene/activated carbon composite material, a preparation method and application thereof, belonging to the technical field of nano materials, and comprising a carbon matrix and a two-dimensional flaky material covered on the carbon matrix; the carbon matrix is an activated carbon material and is prepared by high-temperature pyrolysis of magnesium citrate in a high-temperature self-propagating reaction process, the two-dimensional flaky material is a graphene material, and the carbon matrix is a carbon material with fewer layers of carbon atoms arranged according to honeycomb-shaped two-dimensional lattices and prepared by converting CO 2 through the high-temperature self-propagating reaction. According to the invention, graphene is used as a double skeleton of a conductive structure, a multistage pore structure is constructed by utilizing gas production and template effect in the reaction process, and the electrochemical performance of the active carbon anode is improved. The proper amount of graphene can provide more active sites, simultaneously maintain structural stability, remarkably improve specific capacity and cycle life, and has wide application prospect, thus being particularly suitable for preparing high-performance lithium ion capacitor anode materials.

Inventors

  • ZHANG XIONG
  • MA YANWEI
  • AN YABIN
  • SUN XIANZHONG
  • LI CHEN

Assignees

  • 中国科学院电工研究所

Dates

Publication Date
20260508
Application Date
20260203

Claims (10)

  1. 1. The graphene/activated carbon composite material is characterized by comprising a carbon matrix and a two-dimensional sheet material covered on the carbon matrix; The carbon matrix is an active carbon material; the two-dimensional sheet material is a graphene material.
  2. 2. The graphene/activated carbon composite material according to claim 1, wherein the carbon matrix is an activated carbon material prepared by high-temperature cracking of magnesium citrate in a high-temperature self-propagating reaction process.
  3. 3. The graphene/activated carbon composite material according to claim 1, wherein the two-dimensional sheet material is a graphene material, and is a carbon material with a small layer of carbon atoms arranged in a honeycomb-shaped two-dimensional lattice, which is prepared by converting CO 2 through a high-temperature self-propagating reaction.
  4. 4. The preparation method of the graphene/activated carbon composite material according to any one of claims 1 to 3, which is characterized by comprising the following steps: after being premixed manually, magnesium powder and magnesium citrate are placed in an airflow crusher, and powder in the mixture is fully dispersed under the actions of airflow shearing and turbulence by high-speed airflow to obtain uniform mixed powder A; placing the uniform mixed powder A in a closed 20L reaction tank, introducing pure CO 2 gas, conducting and heating through a nickel-chromium wire, initiating a high-temperature self-propagating reaction, and naturally cooling for 10-20 min after lasting for a few seconds to obtain a precursor powder product B; and (3) carrying out acid washing, filtering and drying on the precursor powder product B to obtain the graphene/activated carbon composite material.
  5. 5. The preparation method of claim 4, wherein the mass ratio of the magnesium powder to the magnesium citrate powder is 1:1-1:5.
  6. 6. The method according to claim 4, wherein the initial temperature of the high-temperature self-propagating reaction is 25 ℃ and the duration is 3-5 s, and the high-temperature self-propagating reaction is performed under the condition of CO 2 atmosphere.
  7. 7. The method according to claim 4, wherein the acid washing is performed with a dilute sulfuric acid solution of 2 mol/L.
  8. 8. Use of the graphene/activated carbon composite material according to any one of claims 1 to 3 or the graphene/activated carbon composite material prepared by the preparation method according to any one of claims 4 to 6 in the positive electrode of a lithium ion capacitor.
  9. 9. A lithium ion capacitor cathode material, characterized by comprising the graphene/activated carbon composite material according to any one of claims 1 to 3.
  10. 10. An energy storage device employing the positive electrode material of claim 9.

Description

Graphene/activated carbon composite material and preparation method and application thereof Technical Field The invention relates to the technical field of nano materials, in particular to a graphene/activated carbon composite material and a preparation method and application thereof. Background With the development of portable electronics, traffic motorization and renewable energy grid connection, energy storage devices are in need of having both high energy density and high power density. Although the lithium ion battery has a high energy density of 150-300 Wh/kg, the power density (< 1000W/kg) and the cycle stability are insufficient due to the limited intercalation/deintercalation reaction kinetics, and the super capacitor has a power of > 5000W/kg and a cycle life of >10 ten thousand times and is limited to an energy density of <10 Wh/kg. Lithium ion capacitors provide a compromise and boost in energy and power by coupling the positive pole of the rapid surface process with the negative pole of the intercalation reaction. However, the conventional active carbon anode relies on electric double-layer energy storage, and has the problems of poor matching of specific surface area and aperture structure with electrolyte ions, high bulk/interface resistance, insufficient electron-ion synergistic channel and the like, so that the multiplying power and capacity output are limited. The graphene has a two-dimensional conjugated structure, excellent conductivity and theoretical specific surface area of up to 2630 m 2/g, the theoretical specific capacitance is about 550F/g, a continuous conductive network can be constructed in an electrode, wetting and pseudocapacitance are improved, but the graphene is easy to agglomerate and stack, and the effective surface area is lost, so that ion diffusion is blocked. Therefore, the graphene/activated carbon composite structure is designed, and through anchoring small-size and fold-rich graphene sheets on an activated carbon framework, agglomeration can be restrained, high effective specific surface area can be kept, and an interconnection electronic channel and a grading channel (micro/medium/macroporous coupling inter-sheet channel) can be formed, so that an ion diffusion path is shortened, polarization is reduced, wetting and surface pseudocapacitance introduction are improved through a proper amount of oxygen-containing functional groups, and therefore, high-capacity, high-multiplying power and high-coulomb efficiency collaborative improvement is realized in a wide voltage window. However, the conventional preparation methods (such as chemical vapor deposition, electrochemical stripping, etc.) of graphene-based composite materials generally require toxic or expensive precursors, and the preparation process is complex, which limits the large-scale popularization of the technology. Therefore, how to develop a green, simple and low-cost graphene-based composite material preparation method becomes an important research point in the field. Disclosure of Invention In view of the above, the invention aims to provide a graphene/activated carbon composite material, and a preparation method and application thereof. The graphene/activated carbon composite material has higher conductivity and a stable structure. In order to achieve the above object, the present invention provides the following technical solutions: A graphene/activated carbon composite material comprises a carbon matrix and a two-dimensional sheet material covered on the carbon matrix; The carbon matrix is an active carbon material; the two-dimensional flaky material is a graphene material; Preferably, the carbon matrix is an activated carbon material, and is prepared by high-temperature pyrolysis of magnesium citrate in the high-temperature self-propagating reaction process. Preferably, the two-dimensional sheet material is a graphene material, and is a carbon material with fewer layers of carbon atoms arranged in a honeycomb two-dimensional lattice, wherein the fewer layers of carbon materials are prepared by converting CO 2 through a high-temperature self-propagating reaction. The invention also provides a preparation method of the graphene/activated carbon composite material, which comprises the following steps: after being premixed manually, magnesium powder and magnesium citrate are placed in an airflow crusher, and powder in the mixture is fully dispersed under the actions of airflow shearing and turbulence by high-speed airflow to obtain uniform mixed powder A; The homogeneous mixed powder A was placed in a closed 20L reaction tank and was aerated with pure CO 2 gas. After conducting heating through a nichrome wire, initiating a high-temperature self-propagating reaction, and after lasting for a few seconds, naturally cooling for 10-20 min to obtain a precursor powder product B; And (3) carrying out acid washing, filtering and freeze-drying on the precursor powder product B to obtain the graphene/activated car