Next generation lithium ion batteries are limited by the cathode material and an incomplete understanding of how the material behaves during operation and degradation. Cathode materials based on layered transition metal oxides traditionally rely on redox of the transition metal centres to compensate the charge when Li-ions are removed. The bulk redox process defines the maximum charge storage capacity of the cathode, however surface processes can significantly influence the ability to access this capacity. Surface reconstruction, electrolyte decomposition, and transition metal dissolution can all influence the ability for Li-ions to be inserted or removed from the cathode with these degradation processes lowering the capacity that can be accessed.
This project will combine surface and bulk sensitive X-ray spectroscopy methods to study how changing the transition metals in multi-component oxides can tune transition metal vs oxygen redox activity in cathode materials. Spectra simulated from model structures will aid in interpretation of experimental data, and there is scope for using machine-learning approaches to classify relevant model structures.
Through this project, you will gain experience in advanced techniques including the preparation and cycling of Li-ion batteries, X-ray spectroscopy, and related analysis of the data obtained. This will make use of state-of-the-art capabilities in Oxford for battery preparation and a lab-based X-ray Absorption Spectrometer. There will further be opportunities to perform measurements at synchrotrons including the nearby Diamond Light Source and other international facilities. There is significant scope to select the focus of the project to be more computational or experimental depending on the interest of the applicant.
Any questions concerning the project can be addressed to Prof Rebecca Nicholls (rebecca.nicholls@materials.ox.ac.uk) and Prof Robert Weatherup (robert.weatherup@materials.ox.ac.uk).
General enquiries on how to apply can be made by e mail to graduate.studies@materials.ox.ac.uk. You must complete the standard Oxford University Application for Graduate Studies. Further information and an electronic copy of the application form can be found at https://www.ox.ac.uk/admissions/graduate/applying-to-oxford.
