Rational Design of Hierarchical FeSe2 Encapsulated with Bifunctional Carbon Cuboids as Advanced Anode for Sodium-ion Batteries
Earth-abundant transition-metal selenides (TMSs) have aroused great interest for application in sodium-ion batteries (SIBs). Herein, we present Fe-based prussian blue analogs (PBA) modified by graphene oxide as precursors to synthesize FeSe2 nanoparticles within nitrogen-doped carbon (NC) matrix and graphene layer (FeSe2/NC@G). The bifunctional carbon wrapped FeSe2/NC@G shows excellent sodium-storage performance with a large reversible capacity of 331 mAh g-1 at 5.0 A g-1 and a high cyclability of 323 mAh g-1 at the current density of 2.0 A g-1 after 1000 cycles (82% capacity retention). Furthermore, full SIBs are also fabricated and demonstrate superior capacities and stabilities. The remarkable electrochemical properties are benefit from the formation of Fe-O-C chemical bond in the composite with enhanced electronic/ionic diffusion kinetics and structural integrity. This study paves the way for resultful synthesis of novel nanostructural TMSs in energy storage systems application.