Recent progress in fundamental understanding of selenium-doped sulfur cathodes during charging and discharging with various electrolytes

Due to the much higher electronic conductivity of selenium (Se) than sulfur (S), selenium doping has shown as an effective strategy to enhance the electrochemical performance of the sulfur cathodes in lithium (Li) metal-sulfur batteries. As a result, the Se-doped S cathode (Se_xS_y) has received increasing interest for next-generation battery systems with high energy density. Since the electrolytes play a critical role in determining the chemistries of both the cathode and the anode, this chapter mainly focuses on the fundamental insights of the Se_xS_y athodes during charge/discharge in various liquid electrolytes and solid-state electrolytes. In addition, recent progress based on cathode structures design for Li-Se_xS_y batteries and suggestions for future development are presented in this chapter.