Superior cycling stability of saturated graphitic carbon nitride in hydrogel reduced graphene oxide anode for Sodium-ion battery

A layered composite g-C3N4@RGO of graphitic carbon nitride (g-C3N4) and reduced graphene oxide (RGO) is reported as an anode material for rechargeable sodium ion batteries (SIBs). Initially, conducting interconnected hydrogel RGO was prepared by hydrothermal method and was further soaked in saturated urea solution, followed by calcination to synthesize g-C3N4@RGO composites. The coin type half cells were prepared by using composite g-C3N4@RGO and pristine RGO as anode and their electrochemical performances were compared. The prepared half-cell of the composite anode delivers maximum reversible specific discharge capacity of ∼ 170 mAh.g−1 and ∼ 160 mAh.g−1 at 0.1C and at 0.2C, respectively. Whereas, prepared half-cell using RGO anode shows maximum reversible discharge capacity of ∼ 146 mAh.g−1 and ∼ 133 mAh.g-1at 0.1C and 0.2C, respectively. This composite material g-C3N4@RGO shows excellent cyclability (2000 cycles) and columbic efficiency ∼ 100% with no capacity fading compared to the RGO. The binding of g-C3N4 with RGO prevents stacking of RGO sheets and provides macro and sub-micron porous structure for smooth intercalation and trapping of Na+-ions in composite g-C3N4@RGO anode during electrochemical cycling. The design of g-C3N4@RGO composite as a negative electrode improves the cell performance and offers effective strategy to develop low-cost and long cycle life SIBs.