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

A super solid electrolyte of Ba-substituted Li 10 GeP 2 S 12 is designed and fabricated to achieve high electrochemical stability. Among the Ba-substituted Li 10 GeP 2 S 12 solid electrolytes, the composition of Li 9.4 Ba 0.3 GeP 2 S 12 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 Li 9.4 Ba 0.3 GeP 2 S 12 is between 0 and 6   V (vs. Li), which is higher than the typical 5   V window of Li 10 GeP 2 S 12 . As compared with Li 10 GeP 2 S 12 , Li 9.4 Ba 0.3 GeP 2 S 12 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 Li 10 GeP 2 S 12 can be attributed to the structural stability resulting from the stable interaction between Ba 2   + and S 2   − in the structure.