ZnO-Doped Li10SnP2S12 with High Lithium Ionic Conductivity and Air Stability

Abstract

Improving the ionic conductivity and stability in the air of sulfide solid-state electrolytes is essential for their practical utilization in solid-state lithium-ion batteries. In this paper, a series of electrolytes Li_10+3xSnP_2–xZn_xS_12–xO_x (x = 0.05, 0.1, 0.15, and 0.2) were prepared by doping Li₁₀SnP₂S₁₂ with ZnO as dopant. Among them, Li_10.15SnP_1.95Zn_0.05S_11.95O_0.05 exhibited the most elevated level of ionic conductivity, achieving a value of 2.56 mS cm^–1. Density-functional theory calculations suggest that doping with ZnO promotes the reduction of the energy barrier for Li⁺ migration. In addition, the electrolyte doped with ZnO showed excellent stability in air. By assembling lithium symmetric batteries, it was demonstrated that the enhanced electrolyte contributed to the stability at the interface with lithium metal. Furthermore, the all-solid-state lithium-ion batteries constructed using the Li_10.15SnP_1.95Zn_0.05S_11.95O_0.05 solid-state electrolyte exhibited superior initial discharge capacity and improved cycling durability compared to those based on Li₁₀SnP₂S₁₂.