基于多硫离子稳态调节的锂硫电池电解液体系设计及其界面反应机制研究

Lithium-sulfur battery a frontier subject in the field of electrochemical energy storage since its high specific capacity and low cost. Excessive electrolyte usage and fast capacity attenuation caused by polysulfide ions dissolution and shuttling are the key problems of Li-S batteries. In view of this problem, this project proposes a study scheme of electrolyte additive based on the stability regulation of polysulfide ions and its interfacial reaction mechanism in Li-S battery. Through the study of the active functional group of the additive molecules and its interaction mechanism with polysulfide ions, the vulcanization accelerator which can reduce the solubility of polysulfide ions in the ether electrolyte will be selected as the additive for lithium sulfur battery electrolyte. Then, the electrolyte additive which can effectively inhibit the shuttle of polysulfide and improve the stability of the Li-S batteries will be obtained. Based on these intellectual technology, the effects of electrolyte additives on the electrochemical properties of Li-S punch cells will be studied and evaluated comprehensively. Finally, a new electrolyte system and a prototype of high specific energy (400Wh/kg) secondary Li-S battery with high performance would be developed by optimizing the additive formulation.

锂硫电池具有高比容与低成本的突出优势，是电化学储能领域的前沿课题。本项目针对多硫离子溶解及穿梭导致电解液用量大且容量衰减快这一锂硫电池发展的瓶颈问题，提出基于多硫离子稳定态调节添加剂的锂硫电池电解液体系设计及其界面反应机制研究。通过研究添加剂分子的活性基团及其与多硫离子的相互作用机制，筛选可降低醚类电解液中多硫化锂溶解量的硫化促进剂作为锂硫电池电解液添加剂，获得能有效抑制锂硫电池中多硫化物穿梭并提高电池循环稳定性的优化电解液配方。在此基础上组装锂硫软包电池，全面研究与评价电解液成分对锂硫软包电池的电化学性能影响。最终通过添加剂组合及配方优化获得高比能（400Wh/kg）二次锂硫电池新型电解液体系与高性能锂硫电池技术原型。

锂硫电池具有高比容与低成本的突出优势，是电化学储能领域的前沿课题。本项目针对多硫离子溶解及穿梭导致电解液用量大且容量衰减快这一锂硫电池发展的瓶颈问题，提出基于多硫离子稳定态调节添加剂的锂硫电池电解液体系设计及其界面反应机制研究。针对多硫化物的特征开发了包括电解液共溶剂、硫化促进剂类、酰胺类、预成膜类锂硫电池用电解液添加剂，获得一系列能改变醚类电解液中多硫化物稳定态的新型锂硫电池电解液添加剂。电解液中添加30 wt% 二硫化碳作为共溶剂时，硫正极的0.5 C循环300圈后放电比容量由587.6 mAh g-1提高到834.6 mAh g-1。采用硫化促进剂四硫化双五亚甲基秋兰姆、预成膜添加剂N-甲基吡咯、硫代乙酰胺作为电解液添加剂的锂硫电池同样在超过300圈后仍有极高的容量保持，远高于常规电解液体系，为推进更高比能锂硫电池的发展提供了理论与技术支撑。