A systematic study on structure, ionic conductivity, and air-stability of xLi4SnS4•(1-x)Li3PS4 solid electrolytes

In order to use sulfide all-solid-state batteries as power sources of electric devices, sulfide solid electrolytes with high ionic conductivity and high air-stability must be developed. Li3PS4 electrolytes have been used in all-solid-state batteries because of their relatively high ionic conductivity (4 x 10(-4) S cm(-1) at 25 degrees C) and higher air-stability than those of other Li2S-P2S5 type solid electrolytes. Herein, the Li4SnS4-Li3PS4 system was investigated to (1) increase the ionic conductivity of Li3PS4 using excess Li carriers and (2) improve the air-stability of Li3PS4 by introducing air-stable Sn-S bonds. The structure, ionic conductivity, and air-stability of xLi(4)SnS(4)center dot(1-x) Li3PS4 were systematically investigated; the results showed that adding small amounts of Li4SnS4 to Li3PS4 glass and glass-ceramic enhanced their ionic conductivity and air-stability without degrading their electrochemical stability. In particular, the 0.3Li(4)SnS(4)center dot 0.7Li(3)PS(4) glass-ceramic showed an ionic conductivity of 8.1 x 10(-4) S cm(-1) at 25 degrees C and generated only a small amount of H2S gas (3 ppm [0.3 cm(3) g(-1)]) when it was dissolved in water. Hence, xLi(4)SnS(4)center dot(1-x)Li3PS4 solid electrolytes can be used as alternatives to the conventional Li3PS4 electrolyte because of their various advantages and a simple preparation method that involves adding only SnS2 to conventional starting materials.

Automated summary

Adding small amounts of Li4SnS4 to Li3PS4 can enhance their ionic conductivity and air-stability without degrading their electrochemical stability. The 0.3Li(4)SnS(4)center dot 0.7Li(3)PS(4) glass-ceramic exhibits high ionic conductivity and generates only a small amount of H2S gas.