Recent work in our laboratory has been directed towards development of mixed layered transition metal oxides
with general composition Li[Ni, Co, M, Mn]O2 (M=Al, Ti) for Li ion battery cathodes. Compounds such as
Li[Ni1/3Co1/3Mn1/3]O2 (often called NMCs) are currently being commercialized for use in consumer electronic batteries,
but the high cobalt content makes them too expensive for vehicular applications such as electric vehicles (EV), plug-in
hybrid electric vehicles (PHEVs), or hybrid electric vehicles (HEVs). To reduce materials costs, we have explored partial
or full substitution of Co with Al, Ti, and Fe. Fe substitution generally decreases capacity and results in poorer rate and
cycling behavior. Interestingly, low levels of substitution with Al or Ti improve aspects of performance with minimal
impact on energy densities, for some formulations. High levels of Al substitution compromise specific capacity,
however, so further improvements require that the Ni and Mn content be increased and Co correspondingly decreased.
Low levels of Al or Ti substitution can then be used offset negative effects induced by the higher Ni content. The
structural and electrochemical characterization of substituted NMCs is presented in this paper.