A Novel Potassium Salt Regulated Solvation Chemistry Enabling Excellent Li Anode Protection in Carbonate Electrolytes.

In lithium metal batteries (LMBs), the compatibility of Li anode and conventional lithium hexafluorophosphate-(LiPF 6 ) carbonate electrolyte is poor owing to the severe parasitic reactions. Herein, to resolve this issue, a delicately designed additive of potassium perfluoropinacolatoborate (KFPB) is unprecedentedly synthesized. On the one hand, KFPB additive can regulate the solvation structure of the carbonate electrolyte, promoting the formation of Li + -FPB - and K + -PF 6 - ion-pairs with lower lowest unoccupied molecular orbital (LUMO) energy levels; On the other hand, FPB - anion possesses strong adsorption ability on Li anode.Thus, anions can preferentially adsorb and decompose on the Li anode surface to form a conductive and robust solid electrolyte interphase (SEI) layer. Only a trace amount of KFPB additive (0.03 M) in the carbonate electrolyte, Li dendrites growth can be totally suppressed and Li||Cu and Li||Li half cells exhibit excellent Li plating/stripping stability upon cycling. Encouragingly, KFPB assisted carbonate electrolyte enables high areal capacity LiCoO 2 ||Li, LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)||Li, and LiNi 0.8 Co 0.05 Al 0.15 O 2 (NCA)||Li LMBs with superior cycling stability, showing its excellent universality. This work reveals the importance of designing novel additives to regulate the solvation structure of carbonate electrolytes in improving its interface compatibility with the Li anode. This article is protected by copyright. All rights reserved.