Stable sodium-sulfur electrochemistry enabled by phosphorus-based complexation
Chuanlong Wang, Yue Zhang, Yue Zhang, Yiwen Zhang, Yiwen Zhang, Jianmin Luo, Xiaofei Hu, Edward Matios, Jackson Crane, Rui Xu, Hai Wang, Weiyang Li
Abstract
A series of sodium phosphorothioate complexes are shown to have electrochemical properties attractive for sodium-sulfur battery applications across a wide operating temperature range. As cathode materials, they resolve a long-standing issue of cyclic liquid-solid phase transition that causes sluggish reaction kinetics and poor cycling stability in conventional, room-temperature sodium-sulfur batteries. The cathode chemistry yields 80% cyclic retention after 400 cycles at room temperature and a superior low-temperature performance down to -60 °C. Coupled experimental characterization and density functional theory calculations revealed the complex structures and electrochemical reaction mechanisms. The desirable electrochemical properties are attributed to the ability of the complexes to prevent the formation of solid precipitates over a fairly wide range of voltage.