High Capacity Li-Rich Cathode Materials

The need for better batteries has never been greater. Many automotive manufacturers now believe that limitations in the performance of current lithium-ion batteries represent the greatest barrier to the electrification of transport. Lithium batteries may also play a critical role in de-carbonization of the electricity grid.

Lithium rich layered cathodes, which offer increased capacity, have, for several years, been regarded as the next major advance, but 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 a new sol-gel synthesis for compositions such as Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ and discuss their limitations and operation. In addition the mechanisms of charge compensation, oxygen loss vs oxygen redox, will be considered. The electrochemical performance is shown in Figure 1. The characteristic load cure is seen with a significant first cycle irreversible capacity; the implications of this will be discussed. The cycling stability of the material is good with a capacity of ~250 mAh g^-1 maintained after 100 cycles.