Co-Co9S8-NC particles anchored on 3D hyperfine carbon nanofiber networks with a hierarchical structure as a catalyst promoting polysulfide conversion for lithium-sulfur batteries

The shuttle effect of lithium polysulfides (LiPSs) has been an important factor limiting the practical application of lithium-sulfur (Li-S) batteries. To inhibit the shuttle effect and accelerate the conversion of LiPSs to Li2S, Co-Co9S8-nitrogen-doped carbon (NC) particles anchored on 3D hyperfine carbon nanofiber networks with a hierarchical structure (CNF/Co-Co9S8-NC) were prepared to modify the Li-S battery separator. In our work, ZIF-67-derived Co-Co9S8-NC particles were anchored on 3D CNF networks derived from bacterial celluloses. CNF networks can provide a highly conductive channel for the transport of ions and electrons, and the 3D structural networks also limit the shuttle of LiPSs to a certain extent, while Co-Co9S8-NC particles, as a highly efficient adsorbent and catalyst for LiPSs, can accelerate the reaction kinetics effectively. Based on the dual limiting effect, the Li-S battery with the CNF/Co-Co9S8-NC modified separator exhibits excellent electrochemical performance. It exhibits a high initial specific capacity of 1582 mA h g(-1) at 0.1 C. Besides, a high reversible discharge capacity of 560.1 mA h g(-1) is obtained over 300 cycles at 2 C with 0.083% decay per cycle. This work shows a novel method for the preparation of heterostructure materials anchored on 3D carbon networks for high-performance Li-S batteries.