Enhancing the electrochemical performances of Li7P3S11 electrolyte through P2O5 substitution for all-solid-state lithium battery

Li 7 P 3 S 11 (70Li 2 S·30P 2 S 5 ) sulfide is a promising electrolyte candidate for all-solid-state lithium batteries (ASSLBs) owing to its high ionic conducivity and wide electrochemical stability window. However, the sensitivity to moisture and the poor interfacial compatibility with electrodes limit the conventional application of Li 7 P 3 S 11 . Herein, we present a substitution strategy to produce a O-incorporated 70Li 2 S·(30-x)P 2 S 5 ·xP 2 O 5 (mol%) sulfide electrolyte to address above issues. The elaborately designed electrolyte is prepared via wet vibration ball milling technique with P 2 O 5 substitution content of 1, 3 and 5. As a result, the 70Li 2 S·27P 2 S 5 ·3P 2 O 5 electrolyte displays the highest ionic conductivity of 2.61× 10 −3  S cm −1 which outperforms than that of pristine Li 7 P 3 S 11 (ionic conductivity of 1.35 × 10 −3  S cm −1 ) and the assembled LiCoO 2 @LiNbO 3 /70Li 2 S·27P 2 S 5 ·3P 2 O 5 /Li-In ASSLB exhibits the superior capacity retention of 93.2% after 100 cycles at 0.5C. The reason for the developed electrochemical performance lies in the substitution of the non-bridging sulfur atom with bridging oxygen atom, from which the interaction between electrolyte and lithium ions is weakened, thereby the rapid transfer of lithium ions is facilitated. Furthermore, Raman and XRD results indicate that the adverse interfacial reactions are suppressed through P 2 O 5 substitution. This work suggests that P 2 O 5 substitution is an effective strategy for sulfide electrolyte toward high energy all-solid-state lithium batteries.