Orbital‐Regulated Stepwise Polysulfide Catalysis Enabled by Ni–Mn D‐Electron Complementarity in Aqueous Polysulfide‐Based Flow Batteries

Aqueous polysulfide‐based redox flow batteries are promising for large‐scale energy storage, yet their practical application is severely hindered by sluggish polysulfide conversion kinetics and the accumulation of intermediate species. Herein, we propose an orbital‐regulated stepwise catalytic strategy based on d‐electron complementarity and construct a NiS/MnS heterostructure to enable efficient polysulfide conversion. Benefiting from the distinct electronic configurations of Ni (3d 8 ) and Mn (3d 5 ), Ni sites provide strong electron‐donation capability to accelerate short‐chain polysulfide reduction, while Mn sites offer spatially distributed electronic states favorable for long‐chain polysulfide adsorption and activation. More importantly, the formation of a Ni─S─Mn configuration establishes a sulfur‐mediated interfacial coupling pathway, enabling directional charge redistribution and spatial separation of catalytic functions. Theoretical calculations reveal enhanced orbital hybridization and increased electronic density near the Fermi level, facilitating rapid charge transfer and strong polysulfide adsorption. When applied in a polysulfide‐based flow battery, the NiS/MnS electrode demonstrates higher energy efficiency, enhanced power density, and excellent cycling stability. This work establishes a general strategy for orbital‐regulated synergistic catalysis via d‐electron complementarity, providing new insights into the rational design of advanced electrocatalysts for high‐performance redox flow batteries.