Sodium sulfate influence on the electrodeposition of MnO2 films for application in Supercapacitors

Abstract

Manganese dioxide (MD) was synthesized by cyclic voltammetry using 0.5 mol L−1 MnSO4·6H2O as the precursor solution, with and without the 0.05 mol L−1 of Na2SO4 support electrolyte solution, and effect was studied by several techniques. The AFM analysis allowed the study of the substrate and synthesized films topography; SEM images showed the differences in the morphology and thickness of the films. Through XRD analysis, it was possible to observe the crystallinity of the materials, caused by the influence of Na2SO4 during electrodeposition and electrochemical characterization, which made it possible to obtain results that served as parameters during the studies proposed here. The voltammograms showed the differences in theoretical capacitance of 0.5 mol L−1 manganese dioxide with Na2SO4 (MDNa) and for 0.5 mol L−1 manganese dioxide without the 0.05 mol L−1 of Na2SO4, which were 860.25 and 455 F g−1, respectively, while in the GCD tests, they present 375 and 250 F g−1 of specific capacitance for the 0.5 mol L−1 MDNa and 0.5 mol L−1 MD electrodes; all results measured in 0.5 A g−1. The EIS studies by the Nyquist and Bode plots made it possible to analyze the resistivity regions and the capacitive nature of the materials. It can be concluded that the purpose of this study was successfully achieved, since the results are interrelated and confirm that the MDNa electrode has attractive and more advantageous properties than MD for supercapacitor application.