A facile strategy to improve the electrochemical stability of a lithium ion conducting Li10GeP2S12 solid electrolyte

A super solid electrolyte of Ba-substituted Li10GeP2S12 is designed and fabricated to achieve high electrochemical stability. Among the Ba-substituted Li10GeP2S12 solid electrolytes, the composition of Li9.4Ba0.3GeP2S12 exhibits the highest ionic conductivity of 7.04 × 10− 4 S cm− 1 with an activation energy of 28.27 kJ mol− 1 at 25 °C. The electrochemical window of Li9.4Ba0.3GeP2S12 is between 0 and 6 V (vs. Li), which is higher than the typical 5 V window of Li10GeP2S12. As compared with Li10GeP2S12, Li9.4Ba0.3GeP2S12 demonstrates a significantly reduced polarization and a better cycle stability though its ionic conductivity is slightly lower than that of the former. The electrochemical stability of Ba-substituted Li10GeP2S12 can be attributed to the structural stability resulting from the stable interaction between Ba2 + and S2 − in the structure.