Zn-doped FeOOH-polypyrrole electrodes for supercapacitors

The problem of poor cyclic stability of FeOOH anodes for supercapacitors was addressed by Zn-doping. Zn-doped FeOOH materials exhibited significant improvement in capacitance retention during cycling. Further improvement in capacitance retention and capacitive properties at low absolute values of negative potentials was achieved in composites containing Zn-doped FeOOH and polypyrrole-coated carbon nanotubes. Another important finding was a simple procedure for the fabrication of MnO2 cathodes, which avoided particle agglomeration during the drying stage and facilitated enhanced mixing of MnO2 and conductive carbon nanotube additives. Enhanced capacitive properties of cathodes and anodes at high active mass loadings allowed good capacitive behavior of the asymmetric devices, which showed promising charge-storage properties for practical applications.