Electrochemical Nanoflakes Manganese Dioxide as Materials for Supercapacitor

T.A. Ha, M.L.P. Le, T.P.T. Nguyen, V.M. Tran
Vietnam National University - Ho Chi Minh City, VN

Keywords: electrochemical capacitor, manganese dioxide, nanoflake

Summary:

Nano structured manganese oxide (MnO2) has been thoroughly investigated because of its potential applications in catalysis for organic synthesis, water treatment and energy storage devices. Various chemical methods have been proposed for nanostructured manganese oxides preparation such as chemical reduction, electrochemical deposition and sol-gel, among them the electrochemical deposition is preferred due to its ability to control the film thickness, structure and morphology. In this work, thin films of CA-MnO2 and CV-MnO2 nanoflakes were synthesized directly on the stainless steel substrate by electrochemical deposition using, respectively, chronoamperometry (CA) and cyclic voltammetry (CV) techniques. The XRD and FTIR analysis indicated the amorphous structure of synthesized MnO2 products. The nanoflake structure of MnO2 with porous and homogenous surface was revealed from SEM images of CA-MnO2 and CV-MnO2. The deposition method and time affected the product morphology. The synthesized MnO2 nanoflakes were used as electrodes materials for electrochemical capacitor assembled with 1 M Na2SO4 aqueous solution as the electrolyte and a Whatman membrane as the separator. The higher specific capacitance (SC) of CV-MnO2 was attributed to its higher porosity in comparison with CA-MnO2. The charge-discharge test showed that all samples exhibited good cycle behavior, less than 2% capacitance loss after 5000 cycles.