ELECTROCHEMICAL LITHIUM INSERTION INTO LAYERED MANGANATES

Various dehydrated phyllomanganates AxMnOalmost-equal-to2 containing A = Na, K or NH4 as interlayer cations A were intercalated with lithium using cells AxMnOalmost-equal-to2-graphite \ LiClO4-PC \ Li. Potentiostatic discharge at low scanning speeds showed two main reaction peaks at ca. 3 V and below 2 V. The first one corresponds to reduction to a disordered Mn3+ phase (DELTAx almost-equal-to 0.6) and was found reversible for A = Na and K. The capacity of sodium phyllomanganate at the third cycle is 188 mAh/kg, i.e. ca. 560 Wh/kg. No marked difference was found as a function of A or of the degree of order of the starting compound.