Selenium@Hollow mesoporous carbon composites for high-rate and long-cycling lithium/sodium-ion batteries

Abstract Selenium (Se) is a prospective candidate of electrode material for high-energy batteries. However, the low Se loading, volumetric expansion and polyselenide shuttling between cathode and anode are major factors to limit further development. To overcome above issues, the hollow carbon structure with interconnected mesopores is used to confine Se composite via a facile annealing treatment route. The Se/HMCS electrode exhibits excellent performance, including a long cycle life (710 mA h g−1 at the 800th cycle at 0.5 A g−1 for LIBs and 291 mA h g−1 at the 1500th cycle at 0.5 A g−1 for SIBs). When coupled with LiCoO2 and Na3V2(PO4)3/C in full cells, this electrode also exhibits superior rate capability (181 Wh kg−1total at 20 W kg−1 for LIBs and 130 Wh kg−1total at 52 W kg−1 for SIBs). The excellent electrochemical performance is attributed to the unique hollow structure of HMCS and a large amount of Se encapsulated within mesoporous, which not only promote electronic/ionic transport but also provide additional buffer space to adjust the volumetric expansion of Se and polyselenide during long cycling. This facile and novelty strategy could be easily extended to other materials with low electronic conductivity for advanced energy storage systems.