煤基石墨负极材料的制备及其电化学性能研究
Preparation of coal-based graphite anode materials and study on their electrochemical performance
以无烟煤为前驱体,研究了煤化程度、灰分、石墨化温度等对无烟煤石墨化的影响机制以及煤基石墨微观结构与电化学性能之间的“构效”关系。结果表明,煤化程度高的无烟煤有利于煤基石墨的微晶生长,在相同温度下能够达到更高的石墨化程度。太西煤在2 400℃石墨化后,石墨化度为80.3%,而晋城煤石墨化度仅为74.5%。无烟煤中的灰分有催化石墨化作用,未脱灰样品在低温下石墨化程度较高,具有较高的首次充放电容量;同时灰分的存在会影响煤基石墨的片层结构,使石墨片层存在褶皱,导致煤基石墨的循环稳定性和倍率性能下降。煤基石墨的石墨化度随温度升高而增加,石墨片层结构逐渐发展,电化学性能得到明显提升。脱灰太西煤经2 800℃石墨化处理后所得煤基石墨在0.2 C的首次放电容量达370.8 mAh/g。
Taking anthracite as a precursor,the influences of coalification degree,ash content and graphitization temperature on the graphitization of anthracite are studied,and the “structure-effect” relationship between microstructure and electrochemical properties of coal-based graphite are also explored.It is found that anthracite with a high coalification degree is beneficial to the growth of microcrystals of coal-based graphite,and can reach a higher graphitization degree at the same temperature.After graphitization at 2,400℃,the graphitization degree of Taixi coal reaches 80.3%,while the graphitization degree of Jincheng coal is only 74.5%.The ash in anthracite plays a catalytic role in graphitization.The anthracite samples that have not been deashed show a high degree of graphitization at lower temperature,and deliver a higher first charge-discharge capacity.However,the existence of ash will also affect the lamellar structure of coal-based graphite,resulting in a large number of folds in graphite lamellae,which will lead to the decline of cycle stability and rate performance of coal-based graphite.With the increasing temperature,the graphitization degree of coal-based graphite increases,the graphite lamellar structure develops gradually,and its electrochemical performance is greatly improved.The graphite that is prepared through graphitization of deashed Taixi coal at 2,800℃ exhibits 370.8 mAh·g-1 of first discharge capacity at 0.2 C.
煤基石墨 / 电化学性能 / 锂离子电池 / 石墨化 / 无烟煤
coal-based graphite / electrochemical properties / lithium-ion battery / graphitization / anthracite
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国家自然科学基金面上项目(22178107)
国家自然科学基金面上项目(22178116)
新疆维吾尔自治区重点研发计划项目(2022B01031)
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