Influence of precipitate/supernatant ratio during liquid-phase synthesis of solid electrolyte Li7P3S11

Delicate control of the precipitate/supernatant ratio in the precursor suspension during liquid-phase synthesis of Li 7 P 3 S 11 provides information on how the morphology of the impurities affects the ionic conductivity . In this work, the influence of the precipitate/supernatant ratio on the phase structure, the morphology and the ionic conductivity of Li 7 P 3 S 11 prepared in acetonitrile is studied. It is revealed that in the supernatant-excess region, the excess amorphous “Li 2 S·P 2 S 5 ” finally turns into a poorly ionic conductive phase Li 4 P 2 S 6 which wraps Li 7 P 3 S 11 particles, increasing the interfacial resistance . In the precipitate-excess region, a thio-LISICON III phase turned from the excess precipitate tends to stay within Li 7 P 3 S 11 particles, and therefore its negative influence on the total ionic conductivity is not evident. Consequently, a slight composition shift into the precipitate-excess region benefits the ionic conductivity of the resultant solid electrolyte .