Effects of graphene oxide doping content and pH on energy storage performance of graphene aerogel

The preparation of graphene aerogel (GA) by the sol-gel method has wide application prospects. In this study, the sol-gel method was used to prepare GA composites using resorcinol (R), formaldehyde (F), and graphene oxide (GO) as precursor materials and sodium carbonate (C) as the catalyst. The effects of the pH value and GO in the precursor solution on the energy storage performance of GA materials were studied. The microstructure and morphology of the samples were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen desorption analysis, and scanning electron microscopy (SEM). Cyclic voltammetry (CV), constant current charge–discharge (CP) and electrochemical impedance spectroscopy (EIS) were used to measure the electrochemical properties of the samples in 1 mol·L⁻¹ Na₂SO₄ electrolyte. The results show that different pH values and GO affect the size and number of cluster particles in GA and the three-dimensional structure of GA. When the pH value was 6.3 and the mass fraction of GO was 1% in the precursor solution, the obtained GA sample exhibited superior surface properties and electrochemical performance. At a current density of 1 A·g⁻¹, the specific surface area of the GA was 530 m²·g⁻¹, and the specific capacitance was 364 F·g⁻¹. If the current density was increased to 10 A·g⁻¹, the specific capacitance still reached 229 F·g⁻¹, indicating that the GA sample had better multiplier performance. After 800 cycles at a current density of 1 A·g⁻¹, the specific capacitance retention rate was 76%. In addition, the GA sample was utilized as a symmetrical supercapacitor with high coulomb efficiency. The specific capacitance of the capacitor remained at 98 F·g⁻¹ in a constant current charge–discharge test at a current density of 1 A·g⁻¹. After 800 cycles, a specific capacitance retention rate of 95.9% was maintained by the symmetrical supercapacitor. This study provides a method for improving the electrochemical properties of GA to realize supercapacitors with better performance.