Well-contacted Li/LLZTO interface by citric acid aqueous treatment for solid-state Li metal batteries

Garnet-type Li6.4La3Zr1.4Ta0.6O12 (LLZTO) is a competitive candidate among various solid-state electrolytes (SSEs) because of its high ionic conductivity and stability against Li metal. However, large Li/LLZTO interfacial resistance caused by poor contact due to the Li2CO3 contaminant on LLZTO hinders its practical application. Herein, a well-contacted Li/LLZTO interface was obtained via a simple and mild citric acid aqueous solution treatment. The Li2CO3-free interface after acid treatment shows an obvious decrease in interfacial resistance from 165 to 11.5 Omega cm(2). In addition, the Li symmetric cell with acid-treated electrolyte cycles stably over 300 h under 0.25 mA cm(-2) at 25 degrees C. (C) 2020 Elsevier B.V. All rights reserved.