Syntheses and Electrochemical Properties of PANI/α-MnO_2 Composites with Different Mass Ratios of Starting Aniline to α-MnO_2 for Supercapacitors

Chrysanthemum-like and spherical α-MnO2 particles were synthesized via a chemical co-precipitation route under acidic condition.With the as-prepared α-MnO2 as the oxidant,polyaniline(PANI)/α-MnO2 composites with different mass ratios of starting aniline to α-MnO2 have been successfully synthesized by the oxidative polymerization of aniline in H2SO4 medium.The as-synthesized PANI/α-MnO2 products were characterized by means of XRD,FTIR and SEM.Their electrochemical properties as electrode materials for supercapacitors were investigated via cyclic voltammetry and chronopotentiometry in 1 mol/L Na2SO4 aqueous electrolyte solution.The results show that the maximum specific capacitance of the PANI/α-MnO2 composite prepared with a mass ratio of starting aniline to α-MnO2 of 1∶3 is 64.58 F/g,which is 1.48 times higher than that of pure α-MnO2 when the amount of PANI/α-MnO2 in the electrode is less half that of α-MnO2.Furthermore,over 85% of the initial specific capacitance for the PANI/α-MnO2 composite can be maintained after 600 cycles,while only 57% is obtained for α-MnO2.