Bimetallic Sulfide SnS2/FeS2 Nanosheets as High-Performance Anode Materials for Sodium-Ion Batteries

Transition-metal sulfide SnS2 has aroused wide concern due to its high capacity and nanosheet structure, making it an attractive choice as the anode material in sodium-ion batteries. However, the large volume expansion and poor conductivity of SnS2 lead to inferior cycle stability as well as rate performance. In this work, FeS2 was in situ introduced to synchronously grow with SnS2 on rGO to prepare a heterojunction bimetallic sulfide nanosheet SnS2/FeS2/rGO composite. The composition and distinctive structure facilitate the rapid diffusion of Na+ and improve the charge transfer at the heterogeneous interface, providing sufficient space for volume expansion and improving anode materials' structural stability. SnS2/FeS2/rGO bimetallic sulfide electrode boasts a capacity of 768.3 mA h g–1 at the current density of 0.1 A g–1, and 541.2 mA h g–1 at the current density of 1 A g–1 in sodium-ion batteries, which is superior to that of either single metal sulfide SnS2 or FeS2. TDOS calculation further confirms that the binding of FeS2/SnS2–Na is more stable than FeS2 and SnS2 alone. The superior electrochemical performance of the SnS2/FeS2/rGO composite material makes it a promising candidate for sodium storage.