Abstract
Sulfur cathodes offer a promising solution for high-energy-density, cost-effective, and sustainable energy storage. However, their practical application is limited by sluggish and complex multistep sulfur redox reactions (SRRs), involving both electrochemical and chemical processes. Herein, it is demonstrated that accelerating electrochemical processes, particularly Li(2)S nucleation, over competing chemical pathways is fundamental to minimizing sulfur loss and achieving high-rate performance. To this end, a scalable and cost-effective strategy is presented for synthesizing a series of 3d transition metal-bismuth (TM-Bi) atomic pairs anchored on carbon nitride (CN) and investigate their potential to activate SRRs in lithium-sulfur batteries (LSBs). An initial screening identifies Ni-Bi/CN and Co-Bi/CN as highly effective in improving rate performance. Detailed analysis shows these catalysts promote direct electrochemical transitions and rapid Li(2)S nucleation over competing chemical reactions, enabling high charge-discharge rates while preventing active material loss and enhancing stability. Electrochemical analysis, density functional theory, and operando spectroscopy reveal that TM-Bi pairing shifts d-band states closer to the Fermi level and modulates HOMO-LUMO levels, promoting lithium polysulfide (LiPS) interaction and facilitating efficient charge transfer. These findings offer valuable insights for designing advanced catalysts for LSBs and broader electrocatalytic applications.