Synthesis of Li₇P₃S₁₁ solid electrolyte in ethyl propionate medium for all-solid-state Li-ion battery

In this study, we report a facile wet chemical synthesis method for preparing Li₇P₃S₁₁ solid-state electrolyte using ethyl propionate as the solvent. The structures of the samples were investigated using X-ray diffraction, Raman spectroscopy, and ³¹P nuclear magnetic resonance. The electrochemical properties of the samples were evaluated using cyclic voltammetry, direct current, and alternating-current electrochemical impedance measurements. The Li₇P₃S₁₁ solid electrolyte (SE) exhibited a Li⁺ conductivity of 1.5 × 10^-3 S cm^-1 at 25 °C. The electrochemical measurements confirmed that the synthesized electrolyte is a single Li⁺ conductor with stability up to 5.0 V vs. Li⁺/Li. Furthermore, a solid-state battery (SSB) cell incorporating LiNi_1/3Mn_1/3Co_1/3O₂ and the synthesized Li₇P₃S₁₁ maintained stability for up to 50 cycles, demonstrating the durability of Li₇P₃S₁₁ in high-voltage SSB applications. These results indicate that Li₇P₃S₁₁ SE is a promising candidate for rechargeable solid-state Li-ion batteries.