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AssigneeThe Gillette Company
InventorsStuart M. Davis, Peter R. Moses, Gary Miller
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A process for manufacture of manganese dioxide comprising subjecting an aqueous bath comprising manganese sulfate (MnSO4) and sulfuric acid (H2SO4) to electrolysis in a closed cell wherein the electrolysis bath is maintained at an elevated temperature above 110° C., preferably above 115° C. and at superatmospheric pressure. Desirably the bath can be maintained at an elevated temperature between about 115° C. and 155° C. The electrolysis is carried out preferably at elevated current density of between about 12.5 and 37 Amp/sq.ft (135 and 400 Amp/sq. meter) of the anode surface which allows for smaller or fewer electrolysis units. An MnO2 product having a specific surface area (SSA) within desired range of between 18-45 m2/g can be obtained. A doping agent, preferably a soluble titanium dopant can also be employed to help obtain the desired specific surface area (SSA) of the MnO2 product. The manganese dioxide product when used as cathode active material in zinc/MnO2 alkaline cells results in excellent service life, particularly when the cell is used in high power application.
An electrolysis process for manufacture of manganese dioxide comprising the steps of:
An electrolysis process for manufacture of manganese dioxide comprising the steps of:
An electrolysis process for manufacture of mangan ese dioxide comprising the steps of:
An alkaline battery comprising a negative electrode comprising zinc, an alkaline electrolyte, a separator and a positive electrode comprising manganese dioxide, said manganese dioxide made by the process comprising the steps of:
A manganese dioxide product having a real density between about 4.2 and 4.38 g/cm2 and a specific surface area of between 18 and 45 m2/g.
Dependencies are inferred from the claim text.