Novel lithium-chalcogenide batteries combining S, Se and C characteristics supported by chitosan-derived carbon intertwined with CNTs

Abstract Lithium-sulfur (Li-S) batteries exhibit a high specific capacity (1675 mAh g−1) but poor S conductivity and severe shuttle effects. Selenium (Se) can greatly mitigate these disadvantages, but its theoretical capacity is relatively low (675 mAh g−1). A series of Sx-Sey compounds supported by chitosan-derived carbon with intertwined carbon nanotube (CC + CNT) carriers exhibit the high capacity of S, the stability of Se, and the excellent conductivity of C, complementing their individual defects. S2Se1/CC + CNT shows the best electrochemical performance (833.2 mAh g−1 after 500 cycles). Characterization results reveal the structure–activity relationships and complex reaction mechanisms of the prepared electrode materials. The overall reactions are a combination of basic Li-S and Li-Se reactions. The discharge steps are clearly identifiable, while the reaction sequences are slightly adjusted and fully integrated when charging. This work provides a foundation for future research and for the practical application of chalcogenides in lithium-metal batteries.