Preparation method of anthracite-based hard carbon material combining pre-activation pore-forming and high-temperature carbonization

Abstract

The invention discloses a preparation method of an anthracite-based hard carbon material combining pre-activation pore-forming and high-temperature carbonization, and belongs to the technical field of electrode material preparation. Aiming at the technical bottleneck that an anthracite-based carbon material prepared by traditional direct carbonization or activation is poor in sodium / potassium storage capacity, the method aims at inhibiting microcrystal lengthening in the anthracite high-temperature carbonization process, and comprises the following steps: grinding and selecting to obtain powder with a target particle size; pre-activation: under the protection of an inert atmosphere, introducing an activation atmosphere, and carrying out heat preservation for 1-6 hours; or adding an activating agent according to the mass ratio of the activating agent to the powder being (0.5-4): 1, carrying out solid-phase premixing, and carrying out heat preservation for 1-6 hours under the protection of an inert atmosphere; and under the protection of inert atmosphere, heating to 800-1800 DEG C at the heating rate of 2-20 DEG C / min, and keeping the temperature for 0.5-10 hours. Compared with the carbon material obtained by the process, the anthracite-based hard carbon obtained on the basis of the idea of carbonization after pre-activation has high reversible capacity and high initial coulombic efficiency in sodium ion storage and transportation, and has important application prospects.

Description

technical field [0001] The invention belongs to the technical field of electrode material preparation, and in particular relates to a method for preparing anthracite-based hard carbon materials combined with preactivation pore formation and high-temperature carbonization. Background technique [0002] Sodium / potassium ion batteries are considered to be an important choice for the next generation of secondary ion batteries. Using coal as a low-cost, natural carbon source, top-down directional preparation of carbon anode materials with low voltage platform (widening the full battery voltage window), high first-cycle coulombic efficiency and long cycle life is the key to the development of low-cost sodium / potassium ion batteries. important direction. [0003] Anthracite has the characteristics of high carbon content (>90%), low cost, and easy pretreatment, and is an important choice for the development of high-performance carbon anode materials. It has been reported that t...

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Problems solved by technology

[0004] On the other hand, physical / chemical / catalytic activation is a common method for preparing coal-based porous carbon materials; however, the continuity of the porous carbon microchip layer obtained by direct activation is greatly damaged, and a large number of edge defects are exposed at the electrode-electrolyte interface. Although the sodium / potassium ions can be stored by the adsorption mechanism, the solvent molecules of the electrolyte are prone to irreversible decomposition or irreversible adsorption and reaction with the sodium / potassium ions at the highly active pore walls with unsaturated edges, resulting in low Coulombic efficiency in the first cycle is difficult to apply to practical secondary ion full cells

[0005] The graphite-like crystals in coal-based carbon materials prepared by direct carbonization exhibit long-range order, which is not conducive to the improvement of ion diffusion storage capacity and rate; the microcrystals in porous carbon materials prepared by direct physical / chemical activation are seriously damaged, and a large number of edge structures cause a series of problems. Irreversible effect, resulting in low first effect; in the existing combination of carbonization and activation, there is only a report of "pre-carbonization-post-activation", which is essentially an improvement on the direct activation process, and the obtained carbon material is still a typical porous carbon, which is not applicable For sodium / potassium ion battery negative electrode

From the above analysis, it can be seen that the traditional single carbonization or activation methods cannot meet the requirements for the preparation of high-performance anthracite-based hard carbon materials.

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