RECHARGEABLE 3-V-LI CELLS USING HYDRATED LAMELLAR MANGANESE OXIDE

The synthesis and the electrochemical features of hydrated lamellar ma nganese oxides are reported. We use the reduction of aqueous permangan ate solution by fumaric acid and the oxidation of manganese hydroxide by an aqueous permanganate solution to obtain sol-gel birnessite and c lassical X-exchanged birnessites (X = Li, Al, Na), respectively. The h igh oxidation state of Mn associated with the 2D character of the host lattice allows high specific capacities (150 to 200 Ah kg(-1)) availa ble in the potential range of 4 to 2 V. Interlayer water provides the structural stability of the host lattice required for long cycling. Re chargeable two-electrode Li cells using starved or flooded electrolyte s were built with the cathodic materials. The batteries exhibit a sati sfactory 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 birn essite. This paper demonstrates an interest in cathodic materials base d on oxides containing structural water for use in secondary Li batter ies.