Dynamic anchoring and catalysis via Co-Nb dual sites in lithium-sulfur batteries

Abstract

Single-atom catalysts are promising for lithium-sulfur (Li-S) batteries due to their high degree of atomic utilization and strong interactions with lithium polysulfides (LiPSs). However, the limited number of active sites and their rapid saturation hinder the continuous adsorption and efficient conversion of LiPSs. Herein, we report a bimetallic catalyst comprising single cobalt atoms (Co_SA) and niobium atomic clusters (Nb_AC) anchored on graphene-like nanosheets (Co_SANb_AC/NC), which are synthesized via a cohesive energy-driven selective metal aggregation strategy. This dual-site configuration forms an electronically asymmetric interface, where Nb_AC anchors LiPSs via Coulombic and Lewis acid-base interactions, while Co_SA enables S–S bond polarization and cleavage through d-p orbital coupling. The interfacial charge redistribution and orbital coupling between Co and Nb facilitate electron transfer between catalytic sites. Therefore, the S/Co_SANb_AC/NC cathode maintains a high areal capacity of 6.12 mAh cm⁻² after 60 cycles under a high sulfur loading of 6.2 mg cm⁻². This work demonstrates a rational design strategy for high-performance Li-S cathodes via synergistic bimetallic catalysis.