Synergistic Se‐Doping and Accompanying S‐Vacancies Drive Lattice Distortion and p‐Band Modulation for Enhanced Sodium Storage in Sulfides

ABSTRACT Metal sulfides, especially those containing alloying‐capable metal elements, have shown great potential as sodium storage materials. However, the complex reaction process imposes more stringent requirements on the kinetic rate. A simple lattice distortion strategy is first proposed in this work to engineer the p‐band center of S in Cu ₃ SbS ₃ for enhanced Na ⁺ storage. Though the co‐doping of Se and accompanying S vacancies, the resultant lattice distortion elongated the bonds between metal and nonmetal elements to weaken their orbital hybridization and lift the p‐band center for a high Na ⁺ adsorption. The defects also increase the number of charge carriers for an improved conductivity. All those merits combined to contribute a superior electrochemical reaction kinetic in the Se‐Cu ₃ SbS ₃ @rGO anode. It achieved a high capacity of 569.1 mAh g ⁻¹ at 0.1 A g ⁻¹ , excellent rate capability of 273.6 mAh g ⁻¹ at 50 A g ⁻¹ and superior cycling stability of 387.4 mAh g ⁻¹ (90%) after 1000 cycles at 5 A g ⁻¹ as well as 92% after 150 cycles at 0.5 A g ⁻¹ in the full cells. The insights into the function mechanism of Se‐vacancies doping‐induced lattice distortion offer valuable insights into the design and development of sulfide‐based anode materials and sodium‐ion batteries.