Growth of electrodeposited γ-manganese dioxide from a suspension bath

The addition of solid particles of manganese oxides to the electrolyte of a manganese dioxide production bath (suspension bath process=SBP) allows the anodic current density to be increased to values more than twice that used in the conventional EMD process. This is possible even with the use of titanium anodes which are sensitive to passivation if the current density exceeds critical values. Analysis of deposition conditions and properties of the SBP-EMD shows that the SBP-EMD resembles and EMD which has been deposited at very low current densities. These low current densities are realized by the adsorption of the suspended particles on the anode surface, thereby promoting dendritic crystal growth on the adsorbed particles and increasing the real anode surface by up to a factor of ten. This assumption is able to explain most of the properties found for the SBP-EMD, e.g. X-ray pattern, potential drop, hardness of the deposit, low specific surface area, low content of combined water and high electronic conductivity.