A facile strategy to achieve high conduction and excellent chemical stability of lithium solid electrolytes

Abstract

Lithium solid electrolytes have shown their potential for high-energy density batteries. The use of solid electrolytes will also be able to overcome safety issues associated with conventional carbonate-based electrolytes. However, achieving the combination of high ionic conductivity and excellent electrochemical stability in lithium solid electrolytes is still a major challenge. Herein we report a facile strategy to achieve high conduction and excellent electrochemical stability by the substitution of Cl for O based on the concept of bottleneck size and binding energy. The ionic conductivities of Li_10.42Si_1.5P_1.5Cl_0.08O_11.92 and Li_10.42Ge_1.5P_1.5Cl_0.08O_11.92 are 1.03 × 10⁻⁵ S cm⁻¹ and 3.7 × 10⁻⁵ S cm⁻¹ at 27 °C, respectively, which are 13 orders of magnitude higher than that of the pure Li₃PO₄, and 1 order of magnitude higher than that of the pristine Li_10.5Si_1.5P_1.5O₁₂. The electrochemical stability with metallic lithium is up to 9 V vs. Li⁺/Li, which is one of the widest electrochemical windows of solid electrolytes. This research also addresses the crystal structure, lithium ion migration mechanism, and battery performance.