(中南大学 冶金与环境学院，长沙 410083)
摘 要: 选择4种结构相似但链长不同的链状醚(Gn，n=1~4)和环状醚1,3-二氧戊环(DOL)作为锂硫电池的电解液溶剂，研究不同的醚种类及组成对锂硫电池电化学性能的影响规律，探讨溶剂性质与锂硫电池性能之间可能存在的内部联系。结果表明:高黏性溶剂会降低锂硫电池的低电位放电平台；使用纯链状醚作溶剂时，溶剂的施主数(DN值)与锂硫电池性能密切相关，锂硫电池在高DN值溶剂中虽易发生过充、库仑效率低，但若控制DN小于19时，锂硫电池循环期间放电容量更高。因此，在合理范围内，增加多硫化物在电解液中的溶解性有利于提高活性材料的利用率；而当引入DOL与链状醚混合使用时，金属锂/电解液的界面性质一定程度上决定锂硫电池的性能水平，DOL由于成膜作用可以降低界面阻抗、改善锂硫电池的循环性能，且锂硫电池容量与库仑效率均随混合溶剂中 DOL含量的增加而逐步提高，但DOL含量不宜过高，锂硫电池在适中的混合溶剂配比下才具有较好的循环稳定性。
关键字: 锂硫电池；电解液；醚；溶剂；电化学性能
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:Four kinds of chain ethers with similar glyme-based structure and different chain length (Gn, n=1~4) and cyclic ether of 1,3-dioxolane (DOL) were selected as electrolyte solvent for lithium/sulfur (Li/S) battery. The effects of ether type and constitution on electrochemical performance of the cell were investigated, and possible relationships between basic properties of these ethers and cell performance were discussed. The results show that the low-potential discharging plateau of the cell will decline if the viscosity of the ether is high relatively. The cell performance is closely associated to the donor number (DN) of the ether when single chain ether is used as electrolyte solvent. For the case with high DN value, the severe overcharging behavior arises more easily, and the coulombic efficiency is lower than that of low DN value, but the higher reversible capacity can be obtained if the DN below is controlled to less than 19. So, increasing the solubility of polysulfides in the electrolyte within reasonable range is beneficial to improve the utilization of active material and the cell capacity. On the other hand, the interfacial properties between Li metal and electrolyte play a Key role in the cell performance when mixing different chain ethers with DOL. The presence of DOL reduces distinctly the impedance of the Li/electrolyte interface and improves the cycling capability of the cell. The discharge capacity and coulombic efficiency increase with the increase of DOL content in the mixed solvent system, but excess DOL in the electrolyte should be avoided. The optimized cycle performance appears in the appropriate mixing ratio of G1 to DOL.
Key words: lithium sulfur battery; electrolyte; ether; solvent; electrochemical performance
