Improving accessible Li-ion cathode capacity through morphological control

Morphology-function relationships have been successfully exploited in many areas of oxide synthesis, including for cathode materials across the Li and Na-ion fields. Despite its relatively recent development, NMC811 has been synthesised by a variety of methods including hydrothermal and sol-gel. Although these methods give some control over particle size, they offer no control of crystal shape, which could be exploited to aid Li (de)intercalaction, and tend to produce heavily agglomerated particles. These can suffer from cracking and areas of inaccessible Li, and so there is space for improvement of these types of cathode through control of crystallite shape to minimise these effects.

Biotemplating, the use of biologically derived long-chain polymers to control crystallisation during calcination, is a technique which enables such control of morphology. The technique has been successfully used to create nano- and micron-scale structures in a wide variety of oxides. It has been shown to control particle shape whilst reducing the energy required for production, although this was without targeted shape control.

This project will seek to improve specific capacity and mechanical stability through targeted control of crystallite morphology in NMC811 and related materials using biotemplating and similar techniques. Specific shapes e.g. nanowires or hollow polycrystalline spheres will be synthesised and characterised. There will be scope for materials to be informed by WP1 and 3 of FutureCat, and will link well into the novel manufacturing of electrodes in WP5 which will seek scalable primary or secondary particle feedstocks which can accommodate volume changes during cycling. This also links into other projects such as CatMat and NEXGENNa, where similar cathode materials could benefit from these types of synthesis methods. We will use the synthesis, powder scale-up and characterisation facilities available in the Materials department and the Royce at Sheffield.