Dual‐Function Sacrificing Template‐Directed Strategy for Constructing Hollow and Core‐Shell Nonstoichiometric Fe_1–xS@C Microspheres Exhibiting Ultrafast Sodium Storage

Abstract Nanostructure design and surface engineering are considered to not only improve the conductivity and buffer the severe volume expansion, but also prevent discharge products dissolving into the electrolyte, boosting the sodium storage performances of iron sulfides. Herein, we developed a dual‐function sacrificing template‐engaged strategy to construct hollow and core‐shell Fe_1–xS‐based microspheres (labeled as Fe_1–xS@C). Benefiting from its unique structural feature, the Fe_1–xS@C composite, as a anode material for sodium‐ion batteries, delivers a high specific capacity of about 700 mAh g⁻¹ at 0.2 A g⁻¹ after 100 cycles and an excellent rate capability of 444 mAh g⁻¹ at 20 A g⁻¹. Impressively, such a strategy can be further extended to prepare hollow and core‐shell NiS@C spheres with slight modifications.