An Effective Single‐Atom Catalytic Descriptor for Accelerating Sulfur Reduction Reaction in Lithium‐Sulfur Batteries

ABSTRACT The solid‐solid Li 2 S 2 ‐to‐Li 2 S transition represents a fundamental bottleneck in sulfur electrochemistry, critically governing reaction kinetics and energy efficiency in lithium‐sulfur batteries (LSBs). While single‐atom catalysts (SACs) show promise in modulating this process, the absence of intrinsic descriptors linking atomic‐scale electronic properties to macroscopic catalytic performance has hindered rational catalyst design. Here, we establish a universal electronic descriptor, θ‐χ, defined as the difference between the valence electron count (θ) and electronegativity (χ) of transition metal (TM) centers. This descriptor quantitatively correlates d ‐band modulation and interfacial charge redistribution with catalytic activity, circumventing the conventional reliance on polysulfide adsorption configurations. Systematic screening across 3 d /4 d ‐TM@nitrogen‐doped graphene (NG) systems reveals a strong θ‐χ dependence of the energy barriers for the Li 2 S 2 ‐to‐Li 2 S conversion, with a correlation coefficient ( R 2 ) of about 0.90. Descriptor‐guided screening not only identifies V@NG, Ti@NG, and Nb@NG as outperforming benchmark catalysts consistent with experimental validation but also uncovers the Mo@NG system, which exhibits superior catalytic activity. Notably, θ‐χ exhibits transferability to sodium‐sulfur batteries (NSBs), accurately predicting Na 2 S 2 ‐to‐Na 2 S kinetics trends without requiring system‐specific recalibration. This work marks a paradigm shift from configuration‐dependent simulations to electronic‐structure‐driven catalyst design, providing atomic‐level insights into sulfur electrochemistry for both LSBs and NSBs catalysts.