Electrolytic manganese dioxide (EMD) was prepared from manganese cake, a by-product obtained during processing of deep sea ocean nodules through the NH3-SO2 leaching route. The samples were characterized by XRD, SEM and their discharge capacity was determined. It was found that the EMD obtained was of γ-variety with spherical and uniform particles. The EMD produced from manganese cake showed a highest discharge capacity of 290 mAh/g which is industrially acceptable value for preparing primary alkaline batteries.
Electrolytic Manganese Dioxide (EMD) is used as a cathode mixture material for dry-cell batteries, such as alkaline batteries, zinc-carbon batteries, rechargeable alkaline batteries etc. Natural manganese dioxide (NMD) can be used in the Leclanche cells. But in alkaline, lithium and other "modern" batteries, synthetic manganese dioxide with improved qualities is required. Among the large variety of manganese oxides, γ-type manganese dioxide is widely used (Jantscher et al., 1999) as γ-variety compounds have high intercalation voltage. Manganese dioxide can be used as a promising material of pseudo capacitor due to its super electrochemical performance, environment friendly nature and lower cost. Manganese dioxide can be prepared both electrolytically and chemically. But γ-manganese dioxide can be produced by electrochemical method that has superior electrochemical properties than chemically prepared manganese dioxide (Chou.s. et.al, 2006). Manganese content in the polymetallic nodules varies between 20 – 33% depending upon the location (Das, 2005). Although the primary interest in processing deep-sea nodules is for recovery of nickel, copper, and cobalt, recovery of manganese will add to overall economics of the process. Processing of polymetallic nodules through reductive ammoniacal leaching process (das et al. 1998) followed by demanganisation and solvent-extraction/electrowinning for recovery of Cu, Ni and Co has been developed by IMMT, Bhubaneswar which was tested in pilot scale at CRDL, HZL, Udaipur.
