Lithium rich layered cathodes, which offer increased capacity, have, for several years, been regarded as one of the next major advances, able to store charge by invoking transition metal and oxygen redox processes in the same material. However, they are still challenged by problems such irreversible first cycle capacity, voltage fade on cycling related to changes in the structure. Recently important work has been carried out to better understand the origin of the high capacity and the voltage fade.

In this contribution we shall present data probing the nature of the O redox states in Li rich 3d transition metal oxides, on the nature of O loss probed by isotopic substitution and on the degree of oxygen loss vs oxygen redox.  We shall also report on a new sol-gel synthesis for Li_1.2Mn_0.54Ni_0.13Co_0.13O₂. The electrochemical performance is shown in Figure 1. The cycling stability of the material is good with a capacity of ~250 mAh g^-1 maintained after 100 cycles.

Figure 1. Load curve and cycleability data of sol-gel prepared Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ at a rate of 50 mA h g^-1.