Improving lithium-ion batteries by understanding novel disordered rock-salt cathode materials: a combined electron imaging and modelling study

The leading battery material used for energy storage, lithium cobalt oxide (LCO), has moderate energy density and stability under operating conditions. Furthermore, manufacturing of LCO can have a major environmental impact due to the cost and difficulties associated with the mining of cobalt.  Because of this, the development of novel cathode materials which contain a lower cobalt content has been sought. These materials consist of various stoichiometries and additional transition metals such as manganese and nickel. But a common problem is that the layered cathodes tend to reconstruct at low lithium concentrations which leads to significant capacity fade during cycling. This has led to research on novel disordered rock salt (DRS) cathodes with the idea being that at this stable low-energy state, minimal reconstruction is to be expected during cycling.

Unlike the layered cathode materials, where the lithium layer facilitates percolation through the material, these DRS cathodes do not possess well-defined structural lithium channels and lithium migration is very sensitive to the nature and degree of short-range order (SRO) in the structure.

This project will use advanced electron imaging and diffraction techniques combined with atomistic modelling methods to build an understanding of the detailed nature of SRO in new DRS materials and to relate it to performance.  This understanding can lead to the rational design of disordered rock salt cathodes for next-generation lithium-ion batteries.