Reduced graphene oxide as a stable and high-capacity cathode material for Na-ion batteries

We report the feasibility of using reduced graphene oxide (RGO) as a cost-effective and high performance cathode material for sodium-ion batteries (SIBs). Graphene oxide is synthesized by a modified Hummers' method and reduced using a solid-state microwave irradiation method. The RGO electrode delivers an exceptionally stable discharge capacity of 240 mAh g^-1 with a stable long cycling up to 1000 cycles. A discharge capacity of 134 mAh g^-1 is obtained at a high current density of 600 mA g^-1, and the electrode recovers a capacity of 230 mAh g^-1 when the current density is reset to 15 mA g^-1 after deep cycling, thus demonstrating the excellent stability of the electrode with sodium de/intercalation. The successful use of the RGO electrode demonstrated in this study is expected to facilitate the emergence of low-cost and sustainable carbon-based materials for SIB cathode applications.