Lithium-manganese oxide electrodes with layered-spinel composite structures xLi2MnO3•(1-x)Li1+yMn2-yO4 (0<x<1, 0≤y≤0.33) for lithium batteries

Lithium-manganese oxide electrodes containing structurally integrated domains of layered and spinel phases, represented in two-component notation as xLi(2)MnO(3)(.)(1-x)Li1+yMn2-yO4 (0 < x < 1, 0 <= y <= 0.33), were synthesized and evaluated in lithium cells. During an initial charge to 5 V, lithium and/or lithia (Li2O) are extracted from the spinel and layered components at distinct voltages. When cycled between 5 and 2 V, a rechargeable capacity > 250 mAh/g can be achieved from electrodes prepared at 400 degrees C during the early cycles. The discharge profiles confirm the layered-spinel character of the composite electrodes. The Li2MnO3 Mn(IV) content in the parent structure and the degree to which lithium and lithia are extracted from the electrode during the initial charge can be used to control the average manganese oxidation state at the end of discharge and electrochemical cycling stability. (c) 2005 Elsevier B.V. All rights reserved.