Synthesis and electrochemical properties of nanophase MnO2 by solid-phase reaction (II) - Electrochemical properties of nanophase gamma-MnO2

The electrochemical behavior of nanophase gamma-MnO2 produced by the decomp osition of coordination compound precursors and then acid treatment was inv estigated by using cyclic voltammetry and constant current charge/discharge tests, The results indicated that the nanophase gamma-MnO2 has a better el ectrochemical activity than International Common Sample I(electrolytic mang nese dioxide, abbreviated in S), Their discharge capacities were higher tha n that of S especially at the second discharge step. This favorable perform ance was more remarkable under the condition of heavy load discharge. A rel atively strong polarization was shown at the beginning of the discharge sta ge and then strong depolarizable ability in the following stage. CV curves show that the peak current of nanophase MnO2 is obviously larger than that of S, and it can be concluded that insertion and deinsertion for protons in to the tunnels of crystal lattice of nanophase mangnese dioxide are easier than S after -0.2 V, and dissolution and deposition for Mn(I) and Mn( IL) s pecies are also easier in nanophase MnO2 than in S in the second discharge step.