High stable rate cycling performances of microporous carbon spheres/selenium composite (MPCS/Se) cathode as lithium–selenium battery

Abstract

Loading selenium (Se) into microporous carbon spheres (MPCS) for the use as a cathode material is an efficient method for reducing the volume expansion and dissolution of polyselenides in the lithium-selenium (Li–Se) batteries during cycling. In this study, we produced MPCSs from glucose using a simple and efficient hydrothermal synthesis method, followed by activation of the MPCS with KOH. Selenium particles were homodispersed in the micropores of MPCS by a typical melt-diffusion process. The obtained MPCS/Se composites used as a cathode of Li–Se batteries show high Se loading of nearly 45%, and high capacities as well as stable cycling performance in both carbonate-based LiPF6 electrolyte (565 mAh g−1 at 1 C after 500 cycles) and ether-based LiTFSI electrolyte (480 mAh g−1 at 1 C after 500 cycles). Notably, an outstanding rate capability in the carbonate-based electrolyte and a coulombic efficiency of nearly 100% in both types of electrolytes were observed. The microporous structure of the MPCS material with high conductivity contributes to the excellent electrochemical properties and rate capability, effectively alleviating volume expansion and suppressing dissolution of polyselenides.