Coupling Lattice Strain and Sulfur Vacancy in Tin Monosulfide/Reduced Graphene Oxide Composite for High‐Performance Sodium‐Ion Storage

Sodium‐ion batteries have garnered significant attention as a cost‐effective alternative to lithium‐ion batteries due to the abundance and affordability of sodium precursors. However, the lack of suitable electrode materials with both high capacity and excellent stability continues to hinder their practical viability. Herein, we couple lattice strain and sulfur deficiency effects in a tin monosulfide/reduced graphene oxide composite to enhance sodium storage performance. Experimental results and theoretical calculations reveal that the synergistic effects of lattice strain and sulfur vacancies in tin monosulfide promote rapid (de)intercalation near the surface/edge of the material, thereby enhancing its pseudocapacitive sodium storage properties. Consequently, the strained and defective tin monosulfide/reduced graphene oxide composite demonstrates a high reversible capacity of 511.82 mAh g −1 at 1 A g −1 and an outstanding rate capability of 450.60 mAh g −1 at 3 A g −1 . This study offers an effective strategy for improving sodium storage performance through lattice strain and defect engineering.