US 6,585,881 B2 · Process for manufacture and improved manganese dioxide for electrochemical cells

Abstract

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) 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 is employed to help obtain the desired specific surface area (SSA) of the MnO2 product. The manganese dioxide product in zinc/MnO2 alkaline cells gives excellent service life, particularly in high power application.

Claims33

Dependent claims

An electrolysis process for manufacture of manganese dioxide comprising the steps of:

(a) forming an electrolysis system comprising an anode, a cathode, and an electrolysis bath comprising a solution comprising manganese sulfate (MnSO4), sulfuric acid (H2SO4), water, and
(b) heating said bath to a temperature above 110° C.,
(c) subjecting said bath to electrolysis while maintaining said bath at above 1100 C, and at a current density of between 12.5 and 37 Amp/ft2 (135 Amp/m2 and 400 Amp/m2) of anode surface area, thereby forming manganese dioxide product and hydrogen gas byproduct.

Dependencies are inferred from the claim text.

Process for manufacture and improved manganese dioxide for electrochemical cells

Life of this patent

Process for manufacture and improved manganese dioxide for electrochemical cells

Life of this patent

Abstract

Claims33