Synthesis of a novel cross-linked graphene aerogel/Yb2O3 NPs composite as high performance supercapacitor

Supercapacitors or ultracapacitors as energy storage devices have benefits in comparison to the batteries such as higher power densities, fast charging/discharging rates, and long cycle life. Among various supercapacitor electrode materials, pseudocapacitive transition-metal oxides and 3D porous structures exhibited much higher energy density than that of electrochemical double layer capacitive carbon materials due to their very high surface area and fast mass transport [1]. In present work, cross-linked graphene aerogel (GA) and its composite with transition metal oxide nanoparticles (GA/Yb2O3) were synthesized through a one-step hydrothermal manner by using p-phenylenediamine, graphene oxide and ytterbium salt [2-3]. GA/Yb2O3 characterized by FE-SEM, XRD, and FTIR techniques. The specific surface area was calculated from the Brunauer-Emmett-Teller (BET) plot of the nitrogen adsorption isotherm. The supercapacitive behavior of GA/Yb2O3 electrode investigated by using cyclic voltammetry (CV), continuous CV (CCV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques in 1 M Na2SO4 solution. According to the GCD studies, nanocomposite indicates enhanced supercapacitive performance, where it has capacitance of 510 at 0.8 A/g and high energy density of 53 Wh/Kg. GA/Yb2O3 exhibits an efficient supercapacitive performance due to the presence of efficient graphene/transient metal oxide-based electrode material. Also p-phenylenediamine as a crosslinker considerably improved supercapacapacitor behavior of nanocomposite. In fact, cross-linked structures provides large inter-sheet spacing for transferring the ions quickly and increasing the electroactive material–electrolyte interface area which results excellent performance of the electrode materials.