Iron Telluride-Decorated Reduced Graphene Oxide Hybrid Microspheres as Anode Materials with Improved Na-Ion Storage Properties

Transition-metal telluride materials are studied as the anode materials for Na-ion batteries (NIBs). The FeTe₂-reduced graphene oxide (rGO) hybrid powders (first target material) are prepared via spray pyrolysis and subsequent tellurization. The H₂Te gas treatment transforms the Fe₃O₄-rGO powders to FeTe₂-rGO hybrid powders with FeTe₂ nanocrystals (various sizes <100 nm) embedded within the rGO. The FeTe₂-rGO hybrid powders contain 5 wt % rGO. The Na-ion storage mechanism for FeTe₂ in NIBs is described by FeTe₂ + 4Na⁺ + 4e^-→Fe + 2Na₂Te. The FeTe₂-rGO hybrid discharge process forms metallic Fe nanocrystals and Na₂Te by a conversion reaction of FeTe₂ with Na ions. The discharge capacities of the FeTe₂-rGO hybrid powders for the first and 80th cycles are 493 and 293 mA h g^-1, respectively. The discharge capacities of the bare FeTe₂ powders for the first and 80th cycles are 462 and 83 mA h g^-1, respectively. The FeTe₂-rGO hybrid powders have superior Na-ion storage properties compared to bare FeTe₂ powders owing to their high structural stability and electrical conductivity.