Improved supercapacitive performances of manganese dioxide on acid-treated carbon nanofibers derived from polyaniline

Polyaniline-based carbon nanofibers were treated with a mixed acid and then reacted with potassium permanganate to obtain manganese dioxide/carbon nanofiber composites. The effects of acid treatment time, reaction temperature, reactant ratio, and the addition method of potassium permanganate on the electrochemical properties of composites were studied thoroughly. Results showed that the optimum time for acid treatment was 6 h, the optimum reaction temperature was 70 °C and the optimum reactant ratio was 1:2. Besides, mixing the reactants sufficiently well in advance was critical for the formation of uniformly shaped MnO2 nanoflakes. Moreover, the acid treatment increased the specific capacitance of composites from 88.7 to 166.7 F/g, and the composites achieved a lifespan up to 1000 cycles with 85.08 % capacity retention.