Abstract
The synthesis and the electrochemical features of hydrated lamellar manganese oxides are reported. We use the reduction of aqueous permanganate solution by fumaric acid and the oxidation of manganese hydroxide by an aqueous permanganate solution to obtain sol‐gel birnessite and classical X‐exchanged birnessites (X = Li, Al, Na), respectively. The high oxidation state of Mn associated with the 2D character of the host lattice allows high specific capacities (150 to 200 Ah kg−1) available in the potential range of 4 to 2 V. Interlayer water provides the structural stability of the host lattice required for long cycling. Rechargeable two‐electrode Li cells using starved or flooded electrolytes were built with the cathodic materials. The batteries exhibit a satisfactory behavior with a specific capacity of 160 Ah kg−1 recovered after 30 cycles at the C/20 discharge‐charge rate for the sol‐gel birnessite. This paper demonstrates an interest in cathodic materials based on oxides containing structural water for use in secondary Li batteries.