A room-temperature sodium–sulfur battery with high capacity and stable cycling performance

• Published in: Nature communications Vol. 9; no. 1; pp. 3870 - 12
• Main Authors: Xu, Xiaofu, Zhou, Dong, Qin, Xianying, Lin, Kui, Kang, Feiyu, Li, Baohua, Shanmukaraj, Devaraj, Rojo, Teofilo, Armand, Michel, Wang, Guoxiu
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.09.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 140/146; 147/135; 639/4077/4079/891; 639/638/161; Anodes; Batteries; Cycles; Electrochemistry; Electrolytes; Energy storage; First principles; High temperature; Humanities and Social Sciences; Indium; multidisciplinary; Performance enhancement; Polysulfides; Product safety; Propylene; Redox properties; Room temperature; Science; Science (multidisciplinary); Sodium; Sodium salts; Sodium sulfide; Solvents; Sulfides; Sulfur; Temperature effects
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-06443-3

High-temperature sodium–sulfur batteries operating at 300–350 °C have been commercially applied for large-scale energy storage and conversion. However, the safety concerns greatly inhibit their widespread adoption. Herein, we report a room-temperature sodium–sulfur battery with high electrochemical performances and enhanced safety by employing a “cocktail optimized” electrolyte system, containing propylene carbonate and fluoroethylene carbonate as co-solvents, highly concentrated sodium salt, and indium triiodide as an additive. As verified by first-principle calculation and experimental characterization, the fluoroethylene carbonate solvent and high salt concentration not only dramatically reduce the solubility of sodium polysulfides, but also construct a robust solid-electrolyte interface on the sodium anode upon cycling. Indium triiodide as redox mediator simultaneously increases the kinetic transformation of sodium sulfide on the cathode and forms a passivating indium layer on the anode to prevent it from polysulfide corrosion. The as-developed sodium–sulfur batteries deliver high capacity and long cycling stability. Sodium–sulfur batteries operating at a high temperature between 300 and 350°C have been used commercially, but the safety issue hinders their wider adoption. Here the authors report a “cocktail optimized” electrolyte system that enables higher electrochemical performance and room-temperature operation.