An advanced low-cost cathode composed of graphene-coated Na2.4Fe1.8(SO4)3 nanograins in a 3D graphene network for ultra-stable sodium storage

Iron-based electrodes have attracted great attention for sodium storage because of the distinct cost effectiveness. However, exploring suitable iron-based electrodes with high power density and long duration remains a big challenge. Herein, a spray-drying strategy is adopted to construct graphene-coated Na2.4Fe1.8(SO4)3 nanograins in a 3D graphene microsphere network. The unique structural and compositional advantages endow these electrodes to exhibit outstanding electrochemical properties with remarkable rate performance and long cycle life. Mechanism analyses further explain the outstanding electrochemical properties from the structural aspect.