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

• Published in: Small structures Vol. 5; no. 7
• Main Authors: Zhang, Jialu, Lou, Chenjie, Dong, Lei, Ping, Weiwei, Xiang, Hongfa, Tang, Mingxue, Feng, Xuyong
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.07.2024; Wiley-VCH
• Subjects: all‐solid‐state battery; Ball milling; Conductors; Distortion; Doping; Electrolytes; Ion currents; Li15P4S16Cl3; Lithium ions; local structure; Molten salt electrolytes; NMR; Nuclear magnetic resonance; Solid electrolytes; solid‐state electrolytes; solid‐state nuclear magnetic resonance; Stability
• ISSN: 2688-4062; 2688-4062
• DOI: 10.1002/sstr.202300565

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. Local structure, such as the types of coordinating anions and bond lengths is the key to ion conduction. Herein, selective anion doping and ball milling strategies are used to regulate the site energies and distributions of lithium ions in Li15P4S16Cl3, thus achieving the transition from nonionic conductors to ionic conductors.