Investigation of layered intergrowth LixMyMn1−yO2+z (M=Ni, Co, Al) compounds as positive electrodes for Li-ion batteries

Layered substituted lithium manganese oxides suitable for use as lithium ion battery electrodes may be prepared from the corresponding sodium manganese metal oxide compounds by ion-exchange. Stacking arrangements (O2, O3, or O2/O3 intergrowths) in the lithiated materials are dependent upon the Na/transition metal ratio in the sodium-containing precursors, the degree of substitution, and the identity of the substituting metal. O3 layered materials deliver up to 200 mA h/g at moderate current densities in lithium cell configurations, but convert rapidly to spinels upon cell cycling, while O2 compounds are more stable but deliver less capacity. Intergrowths show intermediate behavior, with higher capacities than pure O2 materials and better phase stability than O3 compounds. Some intergrowth structures do not appear to convert to spinel during normal cycling, suggesting it may be possible to tailor high energy density, phase stable layered manganese oxide electrodes for lithium batteries.