Realization of room temperature lithium metal battery with high Li+ conductive lithium garnet solid electrolyte

Abstract

Garnet structured solid electrolytes are suitable candidates for lithium metal batteries due to their high lithium ion conductivity and good electrochemical stability. However, large electrode-electrolyte interface resistance still remains a major challenge. Here, we demonstrate realization of room temperature quasi-solid-state battery with high lithium ion conducting Li6.5La3Zr1.75Te0.25O12 (Te-LLZ) as solid electrolyte. To overcome the high interface resistance, we have used gold (Au) interlayer between lithium metal and Te-LLZ. By introducing Au buffer layer, we observed a significant reduction in the interface resistance from 1868 Ω cm2 to 30 Ω cm2 with a stable lithium stripping/platting profile, suggesting a homogeneous lithium ion transport at the lithium/Te-LLZ interface. A quasi-solid-state battery with lithium metal as anode, lithium cobalt oxide (LiCoO2) as cathode and surface engineered Te-LLZ electrolyte with polypropylene (PP) interlayer on the cathode side was demonstrated. The fabricated quasi-solid-state battery delivered an initial discharge capacity of 137 mA h g-1 (50 μA cm-2) and 132 mA h g-1 (150 μA cm-2) at room temperature (25 °C) and 60 °C, respectively.