Cations and anions regulation through hybrid ionic liquid electrolytes towards stable lithium metal anode

Lithium (Li) metal batteries have attracted considerable interest as the next-generation energy storage systems. However, their commercialization has long been plagued by the uncontrolled Li deposition and the low Coulombic efficiency of the Li metal anodes (LMAs). Ionic liquids (ILs) show great potential to efficiently prevent the growth of Li dendrite growth via the formation of a steady solid electrolyte interphase (SEI). Herein, we report the synergetic cations and anions regulation through the molecular design in hybrid ILs based electrolytes for a stable LMA with enhanced performance. To be specific, the combination between bis(fluorosulfonyl)imide (FSI-) and bis((trifluoromethylsulfonyl)imide (TFSI-) anions from Li salts and ILs can induce the formation of a robust LiF-rich SEI layer. Meanwhile, the coupling cations from ILs with diverse functional groups could effectively promote the Li-ion transport. Benefitting from the above features, the hybrid electrolytes could ensure a stabilized LMA with a long lifespan of 1200 h. As a proof-of-concept, the corresponding the Li||LiFePO4 full cell demonstrates a remarkable cycling performance over 500 cycles.