High-safety, wide-temperature-range, low-external-pressure and dendrite-free lithium battery with sulfide solid electrolyte

Li metal is considered to be the most ideal anode due to its highest energy density, but traditional lithium-metal liquid-electrolyte battery system suffers from low Coulombic efficiency, repetitive SEI formation, Li dendrite growth, etc. Herein, a new battery configuration is proposed to exploit room-temperature liquid lithium solutions (Li-BP-Ether) as anodes and argyrodite sulfide as solid electrolyte. Such liquid lithium solutions can deliver high safety performance, excellent dendrite suppression capability, low redox potentials, and high conductivity of 12 mS cm−1 at room temperature. Moreover, sulfide solid electrolyte has the highest room-temperature ionic conductivity among all solid electrolytes and ideal mechanical ductility for fully compact layer simply by cold pressing. This battery configuration combines the advantages of these materials and can operate at neglectable external pressure (3 kPa) in a wide temperature range (−20∼50 °C). As a result, a high reversible discharge capacity (140.4 mAh g−1) and high efficiencies (99.7% Coulombic efficiency and >96% energy efficiency after ∼100 cycles) are achieved. Furthermore, this battery demonstrates the best cycle stability and the highest efficiency among all the liquid lithium solution battery systems using solid cathodes reported so far. Overall, this class of battery configuration may open up a promising route for high-energy-density, cost-effective and safe rechargeable lithium batteries.