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

Abstract

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 6Li 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.