Tuning the interface by a soldering method for high performance garnet-type solid-state Li metal battery

Garnet-type solid electrolytes are promising lithium (Li) ion conductors for all-solid-state batteries. However, their poor compatibilities towards Li metal due to their inherently lithiophobic properties severely hinder their practical application in garnet-based solid-state Li metal batteries (SSLBs). Here, we demonstrated a soldering method to modify the surface of garnet ceramic by forming a thin artificial sulfur layer, which results in a homogeneous and stable Li/solid electrolyte interface. This artificial interface effectively enhances the compatibility between the garnet-type solid electrolyte and the Li metal anode. Consequently, the interfacial resistance of sulfur-coated garnet electrolyte is significantly reduced from 1750 Omega cm(2) to 160 Omega cm(2) based on the electrochemical impedance spectroscopy (EIS) measurements on Li symmetric cells. Besides, the symmetric cell exhibits an excellent lifetime of more than 1100 h at a steady state of voltage hysteresis, which indicates a stable and dendrite-free garnet/Li metal interface. The fabricated Li vertical bar garnet vertical bar LiCoO2 SSLB using this novel interfacial treatment delivers a high specific capacity of 126 mAh g(-1) and good cycling stability.