Surface Modification of Partially Reduced Graphene Oxide for Advanced Electrode Material in Rechargeable Sodium Batteries

The use of redox-active organic materials in rechargeable batteries has the potential to improve the field of energy storage by enabling lightweight and flexible green batteries. In addition, replacing lithium with sodium further mitigates the resource limitations and high cost of lithium for Li-ion batteries (LIBs). Herein, graphene oxide (GO) nanosheets were cross-linked by covalently bonded azo compounds to facilitate sodium-ion insertion and increase charge storage capacity. In the processes, diamine functional groups of p-phenylenediamine (PPD) were converted into diazonium salts (DSs), followed by an electrophilic aromatic substitution between the DSs and GO nanosheets to synthesize azobenzene partially reduced graphene oxide compounds (AB-PRGO) for sodium-ion storage. The as-synthesized AB-PRGO is characterized by various techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption/desorption isotherm, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The AB-PRGO was used as a new cathode material in half-cell Na-ion batteries (SIBs). The results revealed that within a given potential window (0.01-3.0 V), the AB-PRGO-based SIB exhibits good cyclic stability, a high specific capacity, and good rate capability while obtaining a specific capacity of 160 mAh g(-1) at 50 mA g(-1) and preserved the capacity for 50 cycles. This work provides an effective route for developing improved organic electrode materials for SIBs.