Strengthening d‐p Orbital‐Hybridization via Coordination Number Regulation of Manganese Single‐Atom Catalysts Toward Fast Kinetic and Long‐Life Sodium–Sulfur Batteries

Abstract

AbstractThe practical application of room‐temperature sodium‐sulfur (RT Na–S) batteries is blocked by the notorious shuttle effect of sodium polysulfides (NaPSs) and sluggish refox reaction kinetics. Single‐atom catalysts (SACs) have been widely studied for boosting the energy storage performance of RT Na‐S batteries. Nevertheless, the catalytic centers of SACs reported so far have focused mainly on symmetrical metal–N4 structures, which offer weak bonding affinity toward polar NaPSs, leading to detrimental shuttle effect and sluggish sulfur conversion kinetics. Herein, a novel asymmetrical Mn–N2 structure is implanted into nitrogen‐doped carbon nanofibers (Mn‐N2/CNs) through thermal NH3 etching of a symmetrical Mn–N2O2 structure. The Mn–N2 structure promotes the bonding affinity and catalytic conversion of NaPSs due to the strengthened d‐p orbital‐hybridization between the d orbital of Mn in the Mn–N2 structure and the p orbital of S in NaPSs. Consequently, Mn‐N2/CNs@S achieves a high capacity of 458 mAh g−1 at 3.0 C with a capacity decay of 0.23% over 2300 cycles. This work offers a promising pathway for regulating the coordination number of SACs with strengthened d‐p orbital‐hybridization for high‐performance RT Na–S batteries.