Electrolytic manganese dioxide and method of manufacturing the same

Abstract

There is provided manganese dioxide to be suitably used for alkaline manganese batteries and manganese batteries to make them excellent both in the initial performance and the storability. There is also provided a method of manufacturing such manganese dioxide. The electrolytic manganese dioxide has a BET specific surface area of less than 30 m.sup.2 /g (preferably less than 27 m.sup.2 /g) and a suspensiveness of less than 50 mg/liter. A method of manufacturing electrolytic manganese dioxide may be a suspension method, wherein manganese oxide is suspended at a rate of 0.01 to 0.2 g/liter in an electrolytic bath containing sulfuric acid at a concentration of 0.4 to 0.55 mol/liter and electrolyzed to produce electrolytic manganese dioxide with an anodic current density of 0.4 to 3.0 A/dm.sup.2 and an electrolytic temperature of 93.degree. to 103.degree. C., the relationship between the anodic current density and the electrolytic temperature being expressed by 103.gtoreq.y.gtoreq.1.67x+92.33 (where x represents the anodic current density and y represents the electrolytic temperature). Alternatively, a method of manufacturing electrolytic manganese dioxide may be a clarification method, wherein manganese dioxide is electrolyzed in an electrolytic bath containing sulfuric acid at a concentration of 0.3 to 0.45 mol/liter without being suspended therein to produce electrolytic manganese dioxide with an anodic current density of 0.4 to 0.9 A/dm.sup.2 and an electrolytic temperature of 94.degree. to 103.degree. C., the relationship between the anodic current density and the electrolytic temperature being expressed by 103.gtoreq.y.gtoreq.10.00x+90.00. In either the suspension method or the clarification method, two or more than two values may be cyclically used for the anodic current density within the defined range. Still alternatively, the suspension method and the clarification method may be alternately used for electrolysis.