Hydrofluoric Acid‐Removable Additive Optimizing Electrode Electrolyte Interphases with Li+ Conductive Moieties for 4.5 V Lithium Metal Batteries

Abstract

AbstractHigh‐voltage lithium metal batteries (LMBs) are capable to achieve the increasing energy density. However, their cycling life is seriously affected by unstable electrolyte/electrode interfaces and capacity instability at high voltage. Herein, a hydrofluoric acid (HF)‐removable additive is proposed to optimize electrode electrolyte interphases for addressing the above issues. N, N‐dimethyl‐4‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl) aniline (DMPATMB) is used as the electrolyte additive to induce PF6− decomposition to form a dense and robust LiF‐rich solid electrolyte interphase (SEI) for suppressing Li dendrite growth. Moreover, DMPATMB can help to form highly Li+ conductive Li3N and LiBO2, which can boost the Li+ transport across SEI and cathode electrolyte interphase (CEI). In addition, DMPATMB can scavenge traced HF in the electrolyte to protect both SEI and CEI from the corrosion. As expected, 4.5 V Li|| LiNi0.6Co0.2Mn0.2O2 batteries with such electrolyte deliver 145 mAh g−1 after 140 cycles at 200 mA g−1. This work provides a novel insight into high‐voltage electrolyte additives for LMBs.