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.