Strategies of Enhancing Ionic Conductivity in Model Solid-State Electrolyte Li₁₅P₄S₁₆Cl₃

High ionic conductivity is the key point in the development of new solid-state electrolytes. Herein, a combining strategy of anion (O2-) doping and structure distortion is applied to enhance the Li+ ion conductivity in Li15P4S16Cl3, thus converting the nonionic conductor into fast ionic conductor. Solid-state Li-6 nuclear magnetic resonance analysis shows redistribution of Li+ ions in Li15P4S16Cl3 with O2- doping or local structure distortion via ball milling, indicating energy changes at different lithium sites. As a result, the activation energy is reduced from 0.50 to 0.35 eV for the ball-milled Li15P4S15.6O0.4Cl3, and the ionic conductivity is enhanced from 10(-9) to 10(-4) S cm(-1). The electrochemical stability of Li15P4S15.6O0.4Cl3 is broadened at the anode side as well. The symmetric cell Li|Li15P4S15.6O0.4Cl3|Li can cycle more than 1000 h with negligible voltage increase. The LiCoO2|Li15P4S15.6O0.4Cl3|Li-Si all-solid-state battery demonstrates an initial capacity of 106 mA h g(-1) and retains 92% capacity after 200 cycles at 0.5 C, highlighting excellent rate performance and electrochemical stability.