In Situ Engineering of Inorganic‐Rich Solid Electrolyte Interphases via Anion Choice Enables Stable, Lithium Anodes

Abstract

The discovery of liquid battery electrolytes that facilitate the formation of stable solid electrolyte interphases (SEIs) to mitigate dendrite formation is imperative to enable lithium anodes in next‐generation energy‐dense batteries. Compared to traditional electrolyte solvents, tetrahydrofuran (THF)‐based electrolyte systems have demonstrated great success in enabling high‐stability lithium anodes by encouraging the decomposition of anions (instead of organic solvent) and thus generating inorganic‐rich SEIs. Herein, by employing a variety of different lithium salts (i.e., LiPF6, LiTFSI, LiFSI, and LiDFOB), we demonstrate that electrolyte anions modulate the inorganic composition and resulting properties of the SEI. Through novel analytical ToF‐SIMS methods, such as hierarchical clustering of depth profiles and compositional analysis using integrated yields, we examine the chemical composition and morphology of the SEIs generated from each electrolyte system. Notably, the LiDFOB electrolyte provides an exceptionally stable system to enable lithium anodes, delivering > 1500 cycles at a current density of 0.5 mAh g−1 and a capacity of 0.5 mAh g−1 in symmetrical cells. Furthermore, Li//LFP cells using this electrolyte demonstrate high‐rate, reversible lithium storage, supplying 139 mAh g(LFP)−1 at C/2 (∼ 0.991 mAh cm−2, @ 0.61 mA cm−2) with 87.5% capacity retention over 300 cycles (average Coulombic efficiency >99.86%).This article is protected by copyright. All rights reserved

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