THE 2D RANCIEITE-TYPE MANGANIC ACID AND ITS ALKALI-EXCHANGED DERIVATIVES .2. ELECTROCHEMICAL-BEHAVIOR

Various layered manganese oxides (phyllomanganates) with the Rancieite structural type were studied for their ability to intercalate lithium in an electrochemical cell. Series of such materials with various interlayer cations (H, Li, Na), various interlayer water contents and various manganese average oxidation states, were investigated, allowing to get precious information on the influence of such key parameters on the electrochemical behavior of phyllomanganates. The water content of electrode materials, different from that of open-air samples, was carefully measured thus allowing to interpret properly electrochemical data. Special attention was given to the first cycles, especially to the influence of an initial charge on the first discharge capacity and on the influence of such electrochemical pretreatment on further intercalation-deintercalation behavior. The electrochemical behavior at first cycles is complex, with the interlayer water playing a major role. Dehydrated materials at T > 200 degrees C showed a large initial capacity of about 220 mAh/g and a good capacity retention over the ten first discharge-charge cycles.