LAUSR

Functional electrolytes that are stable toward both Li metal anode and high-voltage (> 4 V vs. Li/Li+) cathodes play a critical role in the development of high energy density Li metal batteries. Traditional carbonate-based electrolytes can hardly be used in high-voltage lithium metal batteries due to the dendritic Li deposits, low Coulombic efficiency, and anodic unstability in the presence of aggressive cathodes. Herein, we design a concentrated dual-salt electrolyte that achieves high stability for both Li anodes and high-voltage cathodes of LiNi0.5Mn1.5O4 (LNMO) and LiNi0.7Co0.15Mn0.15O2 (NCM). Li||Cu cell in the designed electrolyte shows high Coulombic efficiency of > 98% in long-term plating/stripping for 900 cycles. Li||LNMO and Li||NCM cells realize capacity retention of 88.5% over 500 cycles and 86.2% over 200 cycles with cut-off voltage of 4.9 V and 4.3 V, respectively. Li||LNMO full cell with cathode areal capacity of 1.8 mAh/cm2 and only 3× excess Li was fabricated, and it delivers high capacity retention of 87.8% for 100 cycles. The reasons for the good cycling stability of the cells in concentrated dual-salt electrolyte can be attributed to the reversible dendrite-free deposition/stripping of Li metal anode and stable interfacial layers on both anode and cathode.