Atomic Environment Engineering of Cobalt Single Atom‐Nanocluster Synergistic Sites on Nitrogen‐Doped MXene for Bidirectional Sulfur Electrocatalysis and Uniform Lithium Deposition

ABSTRACT Lithium–sulfur (Li–S) batteries, with a theoretical energy density of 2600 Wh kg −1 , suffer from the shuttling of lithium polysulfides (LiPSs), sluggish sulfur conversions, and uncontrollable growth of Li dendrites. While single‐atom catalysts (SACs) offer potential solutions, their symmetric coordination environments often yield suboptimal adsorption and catalytic efficiency for bidirectional sulfur conversions. Herein, we break from conventional design by engineering a synergistic catalytic architecture comprising cobalt single‐atom (Co SA ) alongside cobalt nanoclusters (Co NC ) on nitrogen‐doped MXene (Co SA ‐Co NC /NMX). Aberration‐corrected high‐angle annular dark field scanning transmission electron microscopy and X‐ray absorption spectroscopy confirm the coexistence of asymmetrical CoN 1 C 3 SAs and Co NC on the NMX nanosheets, while theory calculations reveal that the Co NC as an electronic modulator induces local structural distortion in both the CoN 1 C 3 moieties and NMX support, modulates d ‐band centers of Co and Ti near the Fermi level, and reconstructs the interfacial charge distribution. These atomic environment optimizations collectively enhance LiPS/Li chemisorption, reduce sulfur conversion energy barriers, weaken Li─S bond strength, and homogenize Li deposition, thereby accelerating sulfur reduction/oxidation kinetics and suppressing dendrite growth. Consequently, the Co SA ‐Co NC /NMX based cell delivers a high initial specific capacity of 963.1 mAh g −1 with a low‐capacity degradation rate of 0.035% per cycle over 1000 cycles at 2.0C, outperforming most reported catalytic separators. The Co SA ‐Co NC /NMX maintains stable Li plating/stripping behavior for over 2000 h. Notably, the Co SA ‐Co NC /NMX based pouch cell achieves an exceptional energy density of ∼461 Wh kg −1 and a high capacity of ∼1.4 Ah under a high sulfur loading of 10.0 mg cm −2 and lean electrolyte of 4.5 µL mg −1 . This work establishes a new paradigm in atomic‐environment engineering, providing a unified catalytic strategy to address both sulfur and lithium electrochemistry in next‐generation energy storage systems.