Particle Packing in High-Nickel Content Cathodes

In addition to acquiring intimate knowledge of crystal structure and redox properties, the development of cathode materials requires in-depth analysis of particle properties, including particle shape, size, aggregate arrangement and packing information. This is a critical gap in our knowledge for high-nickel content cathodes.

This project addresses the pressing need for insights into particle packing in high nickel-content NMC particles and how this affects cathode film preparation. This PhD student will work with PI Smith (expert in particle engineering) to fully characterise pristine and coated particles (supplied by co-I Corr) using SEM to identify primary particle size, aggregate size and shape effects and tomography (through microCT capabilities at Sheffield and via beamtime applications to Diamond Light Source) to evaluate 3D aggregate microstructure. We will study commercial samples of NMC-811 and nanostructured and coated NMC-811 particles available through Degradation project partners. Slurries of these various particle types will be analysed using dynamic light scattering and laser diffraction methods to arrive at a complete rheological picture of cathode slurries (e.g. shear profiles, viscosity effects, particle size effects). Slurries studied will follow the Degradation materials roadmap to ensure these results have greatest impact for other project partners, but findings here may also be of interest to other Faraday activities where particle processing is important.

Resulting cathode films will be assessed using SEM, BET and tomography to investigate 3D structure and visualise particle packing. Finally, electrochemical analysis will provide a steer towards optimal particle packing arrangements. This information will enable researchers to (i) identify how rheological and thixotropic effects influence capacity stability with extended cycling and (ii) develop methodologies for consistent cathode film production for reliable cyclability.

This project has clear synergy with several research strands of the Degradation project, including materials design and synthesis and materials degradation, as well as impacts for industry cathode film production.