Encapsulation of sulfur cathodes by sericin-derived carbon/Co3O4 hollow microspheres for the long-term cyclability of lithium-sulfur batteries

For cathodes in lithium-sulfur (Li-S) batteries, increasing research effort has been devoted to hollow-structured transition metal oxides to utilize their morphologies more efficiently and take advantage of their strong polar chemisorption of polysulfides. In this study, we synthesized a novel sulfur@carbon/Co3O4 (S@C/Co3O4) composite via encapsulation of sulfur by sericin-derived carbon/Co3O4 hollow microspheres. With a sulfur content of 67.3%, the synthesized S@C/Co3O4 composite cathode delivered a high initial specific discharge capacity of 1171.6 mAh g(-1) at 0.2 C and excellent rate performance at current densities up to 4 C. It also exhibited excellent long-term cyclability over roughly 1000 cycles at 1 C and 2 C with low decay rates of 0.076% and 0.062%, respectively. The improved electrochemical performance of the S@C/Co3O4 composite mainly stems from strong polar chemisorption of polysulfides by Co3O4, the physical encapsulation sulfur by hollow spheres, and high electrical conductivity of sericin-derived carbon. (C) 2020 Elsevier B.V. All rights reserved.