Identifying Ion Accessibility with Ether-Based Electrolytes to Approach Superior Rate Performance of Sulfur-Doped Carbon Anodes for Sodium-Ion Batteries

Ether-based electrolytes have been recognized as desirable candidates for enhancing the electrochemical performance of sodium-ion batteries. However, the ion-storage electrochemistry in ether-based electrolytes remains poorly understood for promising amorphous carbon anodes. Herein, by coupling the sulfur-doped soft carbon anodes with three different ether-based electrolytes, the electrolyte-dependent electrochemical behavior is revealed, showing that the accessibility of sodium-ion diffusion from electrode interfaces to internal hosts is greatly enhanced in monoglyme-based electrolytes. It enables a superior rate capability than those with diglyme- and tetraglyme-based electrolytes, delivering specific capacities of 590 and 196 mAh g –1 at 0.1 and 10 A g –1, respectively. This work demonstrates that carbon layers and sulfur dopants in the bulk phase of sulfur-doped carbon anodes are efficiently activated with a suitable cointercalation process of small, weakly solvated Na + for sodium-ion storage. It provides an insight into the role of ether-based electrolytes in ion-storage dynamics optimization of carbon materials for sodium-ion batteries.