Experimental and Theoretical Insights Into Synergistic Sn‐N Co‐Doping Enhancing Air Stability and Interfacial Compatibility of Li_5.5PS_4.5Cl_1.5 Electrolytes for All‐Solid‐State Lithium Metal Batteries

Chlorine-rich argyrodite sulfide solid-state electrolytes (SSEs) have risen as prime candidates for all-solid-state lithium batteries (ASSLBs) owing to their superior ionic conductivity and exceptional ductility. Nevertheless, the vile Li incompatibility and moisture sensitivity restrict their commercial applications. Herein, a novel Li_5.6PSn_0.05S_4.3N_0.2Cl_1.5 electrolyte is synthesized via a hetero-pretreated Sn/ N co-doping strategy. The impact of these two elements on the air stability and electrochemical performance is rigorously validated in combination with the first-principles density functional theory (DFT) calculation and the ab initio molecular dynamics (AIMD) simulations. With optimal elemental substitutions, Li_5.65P_0.95Sn_0.05S_4.5Cl_1.5 achieves a high ionic conductivity of 9.54 mS cm^-1 along with remarkable anti-hydrolysis properties. The generation of a Li-Sn alloy at the Li/SSEs interface significantly reduces the Li⁺ migration barrier and promotes uniform lithium deposition. Moreover, the in situ formation of Li₃N within Li_5.7PS_4.3N_0.2Cl_1.5 effectively facilitates Li⁺ migration. Under the synergistic effect of Sn/N, Li_5.6PSn_0.05S_4.3N_0.2Cl_1.5 endows an admirable critical current density of 1.53 mA cm^-2 and splendid cycling performance (900 h at 0.1 mA cm^-2) in lithium symmetric cells. Additionally, ASSLBs fabricated with Li_5.6PSn_0.05S_4.3N_0.2Cl_1.5 reveal satisfactory cycling stability both at room temperature and elevated temperature (50 °C). This study paves the way for advancing the development of Li-compatibility and moisture-resistant SSEs.