Manganese dioxide-based material

An electrochemical cell, which comprises

• an electronically conducting anode;
• an electronically conducting cathode comprising a chemical manganese dioxide which consists essentially of single phase ramsdellite, and has a powder x-ray diffraction pattern (CuK.sub..alpha. radiation) in which
• the ratio of a (110) peak height to a (201) peak height is at least 0.6:1.0,
• the ratio of the (110) peak height to a (221) peak height is at least 1.2:1.0,
• the (110) peak height has a peak width, at half the peak height, of less than 2.degree.2.theta., and
• which has (221) and (420) peaks present as a doublet at about 56.degree.2.theta.;
• and
• an electronically insulating electrolyte separating the anode from the cathode.

A chemical manganese dioxide, consisting essentially of single phase ramsdellite, and having powder x-ray diffraction pattern (CuK.sub..alpha. radiation) in which

• the ratio of a (110) peak height to a (201) peak height is at least 0.6:1.0,
• the ratio of the (110) peak height to a (221) peak height is at least 1.2:1.0,
• the (110) peak height has a peak width, at half the peak height, of less than 2.degree.2.theta., and,
• which has (221) and (420) peaks present as a doublet at about 56.degree.2.theta..