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

Abstract

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.