Microwave Synthesis of Zinc Ammonium Phosphate/Reduced Graphene Oxide Hybrid Composite for High Energy Density Supercapacitors

Abstract

Herein, zinc ammonium phosphate (ZAP) is interluded with reduced graphene oxide (rGO) as a composite (ZAPG2) via microwave synthesis route. The ZAPG2 is investigated by X‐ray diffraction (XRD), Raman, scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and electrochemical studies (cyclic voltammetry, galvanostatic charge discharge, and impedance). The Raman analysis confirms the graphitization of rGO in the ZAP, and XPS confirms the elemental composition. The SEM morphology reveals that rGO spreads over the micropyramidal envelope of ZAP. The ZAPG2//rGO device delivers a higher specific capacitance of 356 F g −1 for 5 m than in 3 m H 2 SO 4 (133.7 F g −1 ) electrolyte at a current density of 1 A g −1 within the potential window of 1.8 V. The cyclic stability of 86.1% for 3 m and 66.6% for 5 m are noted for 5000 charge–discharge cycles. ZAPG2//rGO combination is the first attempt at facilitating better specific capacitances on device performance. This parallels in energy density, as 59.9 W h kg −1 in 3 m and 153.4 W h kg −1 in 5 m driving for the same power density of 448.3 W kg −1 at 1 A g −1 , which suggests the hybrid composite device's practicality for high‐energy supercapacitor applications.