Shuru Chen1 Jianming Zheng1 Ji-Guang Zhang1

1, Pacific Northwest National Laboratory, Richland, Washington, United States

Rechargeable lithium metal batteries (LMBs) are regarded as the “holy grail” of energy storage systems, but the electrolytes that are highly stable with both a lithium metal anode and high-voltage cathodes still remain a great challenge. Here we report a novel “localized high concentration electrolyte (LHCE)” that enables dendrite-free cycling of lithium metal anodes with high coulombic efficiency (99.5%) and excellent capacity retention (>80% after 700 cycles) of Li||LiNi1/3Mn1/3Co1/3O2 batteries. Unlike the high concentration electrolytes reported before, the electrolyte reported in this work exhibits low concentration, low cost, low viscosity, improved conductivity, and good wettability. With selected Li salt and solvent, we further demonstrated a fire-retardant LHCE that exhibits excellent anodic stability even up to 5.0 V and greatly enhances the cycling performance of LMBs. A Li||LiNi0.6Mn0.2Co0.2O2 battery using this electrolyte can retain > 97% capacity after 600 cycles at 1C rate, corresponding to a negligible capacity decay of < 0.005% per cycle. Therefore, this novel electrolyte can enable safe operation of high-energy LMBs for practical applications. Similar electrolytes can also be used in Li-ion batteries and other batteries to largely improve their safety and cyclability.