High-temperature graphitization of coke and lithium storage properties of coke-based graphite

Coal-derived carbon material is considered as a high-quality raw material for artificial graphite. Herein, the demineralized coke was prepared by acid washing, and coke-based graphite samples were prepared by high-temperature graphitization (2000°C–2800°C). The electrochemical performance of coke-based graphite samples was investigated. It is found that the high-temperature graphitization of the coke is inhibited by demineralization treatment. The graphitization degree of graphitized samples decreased after demineralization treatment. The graphitization degree of the graphitized samples at 2800°C from the raw coke and the demineralized coke can reach 74.48% and 68.78%, respectively. Chemical predemineralization treatment can reduce the mesoporous structure and specific surface area of the product. Moreover, onion-like graphite microspheres are found in graphitized samples from the coke before and after demineralization treatment. The order degree of the raw coke graphitization sample is significantly reduced by extending the graphitization preservation time. The electrochemical test results show that the graphitized sample, e.g., CG-2400, from raw coke (without demineralized) has better comprehensive electrochemical performance. The reversible specific capacity is 301.1 mAh/g at 0.1 C (1 C = 372 mAh/g). After 150 cycles at 1 C, the reversible specific capacity reaches 160.1 mAh/g.