Abstract:

To meet the demand for high specific capacity and low-cost electrochemical energy storage materials in new energy generation technology, this paper utilized techniques such as quantum mechanics, molecular dynamics calculations, and electrochemical analysis testing to investigate the adaptability of petroleum coke based sodium ion battery anodes which were developed in the author's laboratory to electrolytes. The petroleum coke based anode materials developed in the laboratory had significant amorphous carbon structural characteristics, which contributed to the insertion/extraction of Na⁺. The charge and discharge tests were completed within the range of 0.01—2.5V. In the first charge discharge cycle, the specific discharge capacities of ester and ether electrolytes were 406.00mAh/g and 381.91mAh/g, with coulombic efficiencies of 85.04% and 90.42%, respectively. In the range of (0.1—3)C, ether electrolytes had better battery magnification performance. Compared to ester electrolytes, ether electrolytes had a higher LUMO energy level and better reduction stability, therefore it was easier for ether to form a thin and stable SEI film on the electrode surface, which helped to reduce the migration impedance of Na⁺. In addition, in the bulk electrolyte, the migration rate of Na⁺ in ether electrolytes was about twice that of ester electrolytes. The infrared and Raman spectroscopy results of the electrolyte indicated that compared with ester electrolytes, PF₆^- in ether electrolytes was more likely to enter the solvated shell and form coordination with Na⁺, which was related to the weak solvation characteristics of ether solvents. The sodium storage behavior of petroleum coke based cathodes in typical electrolytes were analyzed systematically in this study, which helped to promote the application of petroleum coke based anodes and provided theoretical and experimental basis for the development of low-cost, high specific capacity sodium ion battery technology.

Key words: petroleum coke, sodium-ion battery, anode, electrolyte, solvation

摘要：

石油焦基碳材料成本低，储钠性能优秀，最具工业应用潜力，研究开发与石油焦基碳材料相容性更好的电解液，进一步发挥碳负极材料的储钠性能，已得到科研人员越来越多的关注。在实验室开发石油焦碳材料的基础上，从量子力学和分子动力学计算、电化学分析测试等角度，开展石油焦基钠离子电池负极材料与有机电解液的相容性研究，结果表明：实验室开发的石油焦基负极材料具有显著的无定形碳结构特征，有助于Na⁺的嵌入/脱出；0.01~2.5V内完成充放电测试，在首圈充放电循环中，酯类、醚类电解液中放电比容量分别为406.00mAh/g、381.91mAh/g，库仑效率分别为85.04%、90.42%，在(0.1~3)C倍率范围内，醚类电解液的电池倍率性能更好；探究了电极材料在酯类、醚类电解液中电化学性能存在差异的原因，相对酯类电解液，醚类电解液的最低未占据分子轨道（LUMO）能级较高，还原稳定性较好，在电极表面更易形成薄而稳定的固体电解质界面（SEI）膜，有助于减小Na⁺的迁移阻抗，此外在本体电解液中，醚类电解液中Na⁺迁移速率约为酯类电解液的2倍；电解液的红外、拉曼光谱结果表明，与酯类电解液相比，醚类电解液中PF₆^-更容易进入溶剂化壳层与Na⁺形成配位，这与醚类溶剂弱溶剂化特性有关。系统研究石油焦基钠离子电池负极材料在典型电解液中的储钠行为，有助于推动石油焦基负极材料的应用，为低成本、高比容量钠离子电池技术的发展提供理论及实验依据。

关键词: 石油焦, 钠离子电池, 负极, 电解液, 溶剂化