Interconnected Na2Ti3O7 nanotube/g-C3N4/graphene network as high performance anode materials for sodium storage

Abstract

The high-performance anode electrode material has been the major challenge of sodium ion batteries (SIBs). In this paper, we report a facile strategy to fabricate three-dimensional (3D) network structures where Na2Ti3O7 nanotube species are anchored to the composites composed of graphite phase carbon nitride (g-C3N4) and ultrafine graphene, and demonstrates the excellent electrochemical performance as a sodium storage material. The good integration of g-C3N4 and graphene provides more active sites for Na+ insertion/extraction and accommodates the volume expansion of Na2Ti3O7. The Na2Ti3O7 nanotube into these carbon matrix can effectively shorten the transport paths of Na+. Therefore, the Na2Ti3O7NT/g-C3N4/RGO electrode exhibits a superior cycling efficiency and rate capability. When used as the anode material of sodium half-cell, the reversible capacity of the synthesized Na2Ti3O7NT/g-C3N4/RGO composite is as high as 210.8 mAh g−1 after 300 cycles at 0.1 A g−1 and good rate capability (104.7 mAh g−1 at 2 A g−1). After the 50 cycle, the corresponding coulomb efficiency remained basically stable and is up to 98%. In addition, the half-cell provides high energy density of 364 Wh kg−1 at power density of 0.048 W kg−1.