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The spatial distribution and transport characteristics of lithium ions (Li+) in the electrochemical interface region of a lithium anode in a lithium ion battery directly determine Li+ deposition behavior. The regulation of the Li+ solvation sheath on the solid electrolyte interphase (SEI) by electrolyte chemistry is key but challenging. Here, 1 m lithium trifluoroacetate (LiTFA) is induced to the electrolyte to regulate the Li+ solvation sheath, which significantly suppresses Li dendrite formation and enables a high Coulombic efficiency of 98.8% over 500 cycles. With its strong coordination between the carbonyl groups (CO) and Li+, TFA− modulates the environment of the Li+ solvation sheath and facilitates fast desolvation kinetics. In addition, due to relatively smaller lowest unoccupied molecular orbital energy than solvents, TFA− has a preferential reduction to produce a stable SEI with uniform distribution of LiF and Li2O. Such stable SEI effectively reduces the energy barrier for Li+ diffusion, contributing to low nucleation overpotential, fast ion transfer kinetics, and uniform Li+ deposition with high cycling stability. This work provides an alternative insight into the design of interface chemistry in terms of regulating anions in the Li+ solvation sheath. It is anticipated that this anion‐tuned strategy will pave the way to construct stable SEIs for other battery systems. [ABSTRACT FROM AUTHOR]

Lithium Anodes: An Anion-Tuned Solid Electrolyte Interphase with Fast Ion Transfer Kinetics for Stable Lithium Anodes (Adv. Keywords: anions; energy barriers; lithium metal anodes; solid electrolyte interphase; solvation sheaths EN anions energy barriers lithium metal anodes solid electrolyte interphase solvation sheaths 1 1 1 04/16/20 20200414 NES 200414 In article number 1903843, Feng Li and co-workers provide an anion-tuned strategy to regulate the electrolyte chemistry of a Li SP + sp solvation sheath, which not only facilitates fast Li SP + sp desolvation kinetics, but significantly reduces the energy barrier during Li SP + sp diffusion through the solid electrolyte interphase, subsequently contributing to uniform Li SP + sp deposition with high cycling stability. Anions, energy barriers, lithium metal anodes, solid electrolyte interphase, solvation sheaths. [Extracted from the article]