Asymmetrically Coordinated Single-Atom Ni Catalysts on Curved Supports for Efficient Sodium–Sulfur Batteries

Developing efficient single-atom catalysts (SACs) is crucial in alleviating the shuttle effect of sodium polysulfides (NaPSs) and accelerating the sulfur redox reaction kinetics for sodium–sulfur (Na–S) batteries yet remains challenging. Herein, we design and develop a type of single-atom Ni catalyst with an asymmetric Ni–N3S coordination structure supported on curved carbon layers (cNi–N3S/C) for Na–S batteries. Experimental and theoretical calculations reveal that the synergistic effect of the curvature and the asymmetric Ni–N3S coordination induce a localized charge distribution around the Ni centers. The regulated electronic structure with upshifted d-orbital center accelerates the charge transfer, strengthens adsorption energy, and enhances sulfur redox reaction kinetics in Na–S batteries. The resultant Na–S batteries incorporated with cNi–N3S/C delivers a capacity of 422 mAh g–1 at 3.0 C after 2500 cycles and a low-capacity decay rate of only 0.021% per cycle. This work provides valuable insights for developing efficient SACs for Na–S batteries.