Li(4)SiO(4) Doped-Li(7)P(2)S(8)I solid electrolytes with high lithium stability synthesised using liquid-phase shaking

In this study, mechanical milling and liquid-phase shaking are used to synthesise 3Li(2)S·P(2)S(5) LiI·xLi(4)SiO(4) (Li(7)P(2)S(8)I·xLi(4)SiO(4)) solid electrolytes. When mechanical milling is used, the electrolyte samples doped with 10 mol% of Li(4)SiO(4) (Li(7)P(2)S(8)I·10Li(4)SiO(4)) have the highest ionic conductivity at ∼25–130 °C. When liquid-phase shaking is used, they exhibit a relatively high conductivity of 0.85 mS cm(−1) at ∼20 °C, and low activation energy for conduction of 17 kJ mol(−1). A cyclic voltammogram shows that there are no redox peaks between −0.3 and +10 V, other than the main peaks near 0 V (v.s. Li/Li(+)), indicating a wide electrochemical window. The galvanostatic cycling test results demonstrate that the Li(7)P(2)S(8)I·10Li(4)SiO(4) has excellent long-term cycling stability in excess of 680 cycles (1370 h), indicating that it is highly compatible with Li. Thus, Li(7)P(2)S(8)I solid electrolytes doped with Li(4)SiO(4) are synthesised using the liquid-phase shaking method for the first time and achieve a high ionic conductivity of 0.85 mS cm(−1) at 25 °C. This work demonstrates the effects of Li(4)SiO(4) doping, which can be used to improve the ionic conductivity and stability against Li anodes with Li(7)P(2)S(8)I solid electrolytes.