High Current Density and Long Cycle Life Enabled by Sulfide Solid Electrolyte and Dendrite‐Free Liquid Lithium Anode

Abstract Lithium metal is the ideal anode candidate but suffers from great challenges including poor thermodynamic stability in liquid organic electrolytes and dendrite nucleation/growth during the continuous plating/stripping process. To solve the difficulties listed above, here, a battery configuration combining a liquid lithium solution anode, a sulfide solid electrolyte, and an interfacial protection layer is proposed to prevent interfacial reaction between the two components. This configuration combines the advantages of liquid‐lithium‐solution anode (dissolve lithium to essentially prevent lithium nucleation) and sulfide solid electrolyte (highest room‐temperature ionic conductivity among all solid electrolytes and ideal mechanical ductility for fully compact layer simply by cold pressing), so that a record‐high current density (17.78 mA cm −2 ) and long cycle life (nearly 3000 h) are realized. At the same time, the solubility of lithium metal in the liquid Li anode and electrochemical properties of liquid Li anode are systematically studied to find the most suitable liquid Li anode concentration with the highest room‐temperature conductivity (12.2 mS cm −1 ). This work provides a promising approach and battery configuration for achieving high‐specific‐capacity, high‐energy/power‐density and long‐cycle‐life secondary batteries.