Self-assembly synthesis of SnNb2O6/amino-functionalized graphene nanocomposite as high-rate anode materials for sodium-ion batteries

A two-dimensional (2D) SnNb2O6/amino-functionalized graphene (En-RGO) nanocomposite with a representative 2D–2D architecture has been constructed by an easy self-assembly approach and firstly investigated as anode materials for secondary sodium-ion batteries. The SnNb2O6 nanosheets are evenly anchored with the amino-functionalized graphene through electrostatic attractive interplay between the negatively charged SnNb2O6 and positively charged En-RGO after modification. As a result, a remarkable reversible capacity of 300 mAh·g−1 was obtained at 50 mA·g−1, and significantly, the En-RGO electrode could also deliver ultra-long calendar life up to 1900 cycles with a high reversible capacity of 200 mAh·g−1 at current of 500 mA·g−1. Such excellent electrochemical characteristics can be mainly ascribed to its fast pseudo-capacitive energy storage mechanism, and the capacitive contribution can even reach up to 90% at 1.2 mV·s−1.