Double-shelled Zn–Co single-atoms enable enhanced conversion kinetics in lithium–sulfur batteries

Abstract

Due to the high complexity and huge difference in sulfur electrochemistry, single-atom (SA) catalysts with a single component cannot satisfy the urgent need for accelerating the complex redox process of lithium–sulfur batteries (LSBs). Herein, a dual-metal Zn–Co single-atom catalyst loaded on a double-shelled nitrogen-doped carbon material (Zn–Co SA@DNC) is designed to enable the efficient physicochemical confinement and catalytic conversion of lithium polysulfides (LiPSs). Benefiting from the synergistic effect of dual-redox sites and ingenious double-shelled structure of Zn–Co–N8–C, the catalytic energy barrier and outward diffusion of polysulfides are effectively reduced compared with the single-component counterparts (Zn SA@DNC and Co SA@DNC). When utilized as a sulfur host, the Zn–Co SA@DNC/S cathode exhibits satisfactory sulfur electrochemistry, including an excellent reversible performance of 732 mA h g⁻¹ under 1C with a small capacity decay of 0.034% per cycle after 800 cycles and a superior areal capacity of 4.3 mA h cm⁻² with a low electrolyte/sulfur ratio of 9. This work would provide a profound understanding of the catalysis mechanism of dual-metal SAs on accelerating sulfur conversion in LSBs.