A molten battery consisting of Li metal anode, AlCl3-LiCl cathode and solid electrolyte

High performance rechargeable batteries are urgently needed to address the demands of grid-scale stationary energy storage. High temperature battery systems, such as Na-S battery, Na-NiCl2 battery (ZEBRA battery) and liquid metal electrode (LME) battery, exhibit advantages like high power density and high cyclic stability, but also suffer from the high operating temperature. We recently invented new concept of molten lithium metal batteries, consisting of liquid lithium anodes, alloy (Sn, Bi, Pb) liquid cathodes and lithium ion conductor as solid electrolytes. Here we demonstrate a molten metal chloride battery that operates at a relatively low temperature of 210 °C. The battery has been designed to include molten (AlCl3-LiCl) cathode, solid electrolyte (garnet-type Li6.4La3Ta0.6Zr1.4O12 (LLZTO) ceramic tube) and molten lithium anode. The assembled AlCl3-LiCl||LLZTO||Li full cell has an average discharge voltage of 1.55 V and energy efficiency of 83% and has been successfully cycled for 100 cycles (800 h) without capacity fade. The theoretical specific energy of cell is 350 Wh/kg and the estimated cost is $11.6/kWh based on the weight of electrode materials. Considering the high performance, high safety, low operating temperature and low cost of raw materials, our new type of molten-electrode battery system opens up new opportunities for stationary energy storage.