Untangling the design of single-atom Zn catalyst for superior performance in lithium-sulfur batteries

Abstract

The sluggish kinetics of electrochemical reaction and the shuttle effect of sulfur species represent significant challenges hindering the advancement of lithium‑sulfur batteries (LiSBs). In this study, we propose a “tall building on flat ground” strategy to synthesize a single-atom Zn catalyst (MXene-NPC-Zn), where nitrogen-doped porous carbon (NPC) serves as the “tall buildings”, while MXene acts as the foundational “flat ground” supporting the porous carbon. This engineered microstructure provides a large surface area for the deposition of electrochemically inert sulfur and Li₂S while effectively stabilizing Zn single atoms. The incorporation of Zn single atoms enhances catalytic activity, accelerates sulfur species conversion, and facilitates rapid electron transport and efficient lithium-ion transfer during charge-discharge cycles. Consequently, LiSBs with the MXene-NPC-Zn modified separator achieve a high reversible capacity of 1407.3 mAh g⁻¹ at 0.2C and exhibit stable cycling performance at 1C with a low-capacity decay of 0.071 % per cycle. These findings underscore the potential of the single-atom catalyst, synthesized using the “tall building on flat ground” approach, as a promising material for improving the performance of LiSBs.