Journal of Applied Electrochemistry, Vol.47, No.1, 39-49, 2017
Nanostructured manganese oxide and manganese oxide/polyethylenedioxythiophene rods electrodeposited onto nickel foam for supercapacitor applications
A template-free anodic electrodeposition process was utilized to deposit Mn oxide and Mn oxide/PEDOT rods onto Ni foam substrates for use as supercapacitor electrodes. Deposit morphology was optimized by varying deposition conditions and by characterization using electron microscopy. The deposits were poorly crystalline, and electron diffraction patterns could be indexed to either a cubic spinel structure (Mn3O4) or a hexagonal birnessite structure (MnO2). The deposits had an overall oxidation state of Mn3+ before cycling and Mn4+ after 500 cycles. The maximum capacitance values for deposits with and without PEDOT were 159 and 120 F g(-1) (500 and 290 mF cm(-2)), respectively, measured using CV at a scan rate of 5 mV s(-1). The addition of the PEDOT coating reduced Mn oxide dissolution during cycling up to 500 cycles. Uncoated samples showed an increase in capacitance during cycling, which is attributed to the oxidation state change and the redeposition of Mn oxide in areas of high conductivity. Capacitance retentions after 2000 cycles were 46 and 120 % for deposits with and without PEDOT, respectively.