Stable Operation of Lithium Metal Batteries with Aggressive Cathode Chemistries at 4.9 V

Abstract

AbstractHigh‐voltage lithium metal batteries (LMBs) pose severe challenges for the matching of electrolytes with aggressive electrodes, especially at low temperatures. Here, we report a rational modification of the Li+solvation structure to extend the voltage and temperature operating ranges of conventional electrolytes. Ion‐ion and ion‐dipole interactions as well as the electrochemical window of solvents were tailored to improve oxidation stability and de‐solvation kinetics of the electrolyte. Meanwhile, robust and elastic B and F‐rich interphases are formed on both electrodes. Such optimization enables Li||LiNi0.5Mn1.5O4cells (90.2 % retention after 400 cycles) and Li||LiNi0.6Co0.2Mn0.2O2(NCM622) cells (74.0 % retention after 200 cycles) to cycle stably at an ultra‐high voltage of 4.9 V. Moreover, NCM622 cells deliver a considerable capacity of 143.5 mAh g−1at −20 °C, showing great potential for practical uses. The proposed strategy sheds light on further optimization for high‐voltage LMBs.