Anion Donicity of Liquid Electrolytes for Lithium Carbon Fluoride Batteries
Xingxing Wang, Ziyu Song, Hao Wu, Hailong Yu, Wenfang Feng, Michel Armand, Xuejie Huang, Zhibin Zhou, Heng Zhang
Abstract
Abstract The increasing demand for high‐energy powers have greatly incentivized the development of lithium carbon fluoride (Li||CF x ) cells. Five kinds of non‐aqueous liquid electrolytes with various kinds of lithium salts (LiX, X=PF 6 − , TFSI − , BF 4 − , ClO 4 − , and CF 3 SO 3 − ) were comparatively studied. Intriguingly, the LiBF 4 ‐based electrolyte show relatively moderate ionic conductivities; yet, the corresponding Li||CF x cells deliver the highest discharge capacities among them. A combination of morphological and compositional analyses of the discharge CF x cathode suggest that the moderate donicity of BF 4 − anion is accountable for favoring the breakdown of C−F bonds, and subsequently forming crystalline lithium fluoride as the main discharge products. This work brings not only fresh understanding on the role of salt anions for Li||CF x cells, but also inspire the electrolyte design for other conversion‐type (sulfur and/or organosulfur) cathode materials desired for high‐energy applications.