Supercapacitor Based on Nanostructured Multilayer Films Consisting of Polyelectrolyte/Graphene Oxide-MnO2-ZnO for Energy Storage Applications

Abstract

The development of new technologies has increased the demand for energy storage devices with high performance. In this sense, supercapacitors appear as a prominent alternative due to their high power density, fast charge–discharge time, environment friendly, and long-term cycle stability. Carbon materials and transition metal oxides have been reported as attractive materials to achieve supercapacitors with enhanced properties. This study investigates nanostructured films, using the layer-by-layer (LbL) method, consisting of MnO2-ZnO nanostructures embedded into reduced graphene oxide (rGO) and combined with polyallylamine hydrochloride (PAH) polyelectrolyte for supercapacitor applications. The film morphology and the incorporation of MnO2-ZnO nanostructures in rGO layers are analyzed by scanning electron microscopy images. The electrochemical properties are evaluated by cyclic voltammetry and galvanostatic charge–discharge measurements. A high capacitance is reached for a 20-bilayer PAH/rGO-MnO2-ZnO LbL film at a 1 mV s−1 and 1.15 A g−1 with values of 1650 F g−1 and 26 mF cm−2. Furthermore, the film exhibits high energy and power densities of 112.3 Wh kg−1 and 404.4 W kg−1, respectively, as well as high capacitive retention and cycle stability. These findings indicate the potential application of PAH/rGO-MnO2-ZnO LbL films as supercapacitor electrodes and envisage further studies of LbL nanostructured systems for energy storage applications.