NOVELTY - Manganese carbonate is heated and cooled (AA) to produce manganese dioxide seed. The obtained seed is pulverized (BB) to nano powder manganese dioxide in attrition mill. The pulverized manganese dioxide material is added to stirrer and mixed (CC) with sulfuric acid. A mixture (A) of manganese sulfate and distilled water is mixed (DD) to resultant mixture in stirrer. A mixture (B) of sodium chlorite and deionized water is mixed (KK) to the resultant mixture. The resultant mixture is subjected to solid-liquid separation (HH), and chemical manganese dioxide (FF) is separated.    USE - Manufacture of chemical manganese dioxide (claimed) used for cathode material for lithium secondary battery. Chemical manganese dioxide is sued as precursor of cathode material of lithium secondary battery for hybrid electric vehicle.    ADVANTAGE - The method enables manufacture of chemical manganese dioxide with high productivity. The chemical manganese dioxide improves charging and discharging efficiency of lithium secondary battery.    DETAILED DESCRIPTION - Manganese carbonate is heated at 300-450 degrees C and cooled for 30-15 minutes, to produce manganese dioxide seed in powder form. The obtained seed is pulverized to nano powder manganese dioxide seed comprising 10-20 wt.% nano-sized primary particles, by adding 67 wt.% distilled water and 10-13 wt.% ceramic ball in attrition mill. The pulverized manganese dioxide material is added to stirrer and mixed with sulfuric acid. Mixing mixture (A) of manganese sulfate and distilled water to the resultant mixture in stirrer, and then mixing mixture (B) of sodium chlorite and deionized water. The resultant mixture is introduced to a solid-liquid separator for solid-liquid separation, and primary chemical manganese dioxide is separated. The separated mother liquor is recycled within the reactor, to produce chemical manganese dioxide (II) and chemical manganese dioxide (JJ). An INDEPENDENT CLAIM is included for chemical manganese dioxide.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view explaining manufacture of chemical manganese dioxide. (Drawing includes non-English language text)    Heating and cooling manganese carbonate (AA)    Pulverizing process (BB)    Mixing nano manganese dioxide seed with sulfuric acid (CC)    Mixing mixture A (DD)    Chemical manganese dioxides (FF,II,JJ)    Solid-liquid separation (HH)    Mixing mixture B (KK)