Wet-Milling Synthesis of Superionic Lithium Argyrodite Electrolytes with Different Concentrations of Lithium Vacancy

The ionic conductivities of argyrodite electrolytes are significantly affected by the concentrations of lithium vacancy. Herein, a facile and rapid synthesis route is proposed to systematically investigate Li_6-PS_5-Cl₁₊ (0 ≤ x ≤ 0.8) with different lithium vacancies by adjusting ratios of S/Cl. The highest ionic conductivity of the wet-milling synthesized Li_5.4PS_4.4Cl_1.6 is 6.18 mS cm^-1, which is attributed to higher lithium vacancy concentration and lower electrostatic interaction for ion migration. The Li/Li_5.4PS_4.4Cl_1.6/Li symmetric cell cycles stably for 2000 h at 0.1 mA cm^-2, showing excellent dendrite suppression capability. Moreover, the initial discharge capacity of LiCoO₂/Li_5.4PS_4.4Cl_1.6/Li all-solid-state battery is 126.0 mAh g^-1 at 0.1C and the capacity retention is 83% after 50 cycles. The wet-milling method provides the possibility for rapid exploration and preparation of other argyrodite electrolytes in the future.