The Role of the Acidic Electrolyte in the Phase Transformation of Gamma‐EMD to Beta‐Manganese Dioxide

Abstract

The influence of acidic strength of the manganous sulfate electrolyte on the nucleation and growth of ~-MnQ in the gamma-phase electrolytic manganese dioxide (~]-EMD) is examined. It is found that the growth of ~-MnO2 in EMD is firstorder with respect to the bulk acid concentration. It is suggested that the reduction of EMD by Mn 2 § to generate Mn(III) intermediates initiates the phase transformation. The subsequent disproportionation of Mn(III) intermediates produces ~-MnQ. The growth of ~-MnO2 in EMD is controlled by the diffusion of hydrogen ions in the lattice of EMD and the redox of EMD and Mn 2 § ions in the electrolyte via a galvanic type cell through the semiconducting EMD.

Structure Investigation and Electrochemical Behavior of γ-MnO2 Synthesized from Three-Dimensional Framework and Layered Structures

“…1. From this figure, d-MnO 2 appears to be an important precursor to obtain different MnO 2 modifications (14)(15)(16)(17)(18)(19)(20)(21). Also, another observation is the transformation of different modifications to the spinel-like LiMn 2 O 4 upon thermal treatment in the presence of Li.…”