The Key Role of Anion – Cationic Coordination on Anode Electric‐Double‐Layer Evolution for High Performance Lithium Metal Battery

Abstract Inhibiting dendrite growth is considered one of the most crucial tasks for developing high‐energy‐density lithium metal batteries (LMBs), but it is constrained by the unsteady evolution of the electric‐double‐layer (Li‐EDL) at lithium/electrolyte interface. Herein, the dependence of Li‐EDL evolution on the solvation structure is elucidated based on the changes of solid electrolyte interphase (SEI) and electrostatic shielding effect (ESE) in various salt‐anion systems with/ without K + added. It is found that the interaction between anions and cations presents competing effect on SEI or ESE formation, in which medium/high donor number (DN) anion would promote its participation in SEI formation, but the dissociation of K + into Li‐EDL for ESE exhibits a high voltage dependence, resulting in the poor stability of Li‐EDL. Through using PF 6 ‒ (low DN value) to release K + confined by FSI ‒ (medium DN value), a novel designed LiPF 6 ‐LiFSI‐K + ester‐based electrolyte realizes an optimized Li‐EDL with the ability of high quality SEI formation and stable ESE, effectively inhibiting the lithium dendrite formation. The new findings in this study provide an innovative insight on the optimization strategy toward alkali metal anodes community.