Revealing Electrochemical Defects in Commercial Li-ion Cathodes with 3D-DPDF

Supervisor
Dr Alex Rettie
University
University College London
Industry Co-Sponsor
Diamond Light Source
Project Description
The PhD student will develop cutting-edge diffuse scattering techniques and use them on real world battery materials. Single-crystal diffuse scattering (SCDS) is unparalleled in its ability to probe “hidden” short-range order and dilute defects. Single-crystalline electrode particles (i.e., those with no grain boundaries) have recently emerged as leading candidates to enable long cycle-life, Ni-rich batteries, and are commercially available. Dynamic defect structures as functions of temperature, state-of-charge and cycle number will be revealed using the state-of-art X-synchrotron techniques and expertise at Diamond Light Source.

By probing a variety of related cathode chemistries, we will create new, universal design rules needed to advance energy storage and develop a software suite for analysis of SCDS. Years 1 and 4 of the project will be spent at
UCL and years 2 and 3 at Diamond. The student will join the Electrochemical Innovation Lab at UCL, a world leading centre for electrochemical research, gaining expertise in battery electrochemistry, powder X-ray diffraction, Raman spectroscopy and electron microscopy.

Collection of SDCS data under variable temperature, training in crystallography, 3D-DPDF analysis and automation of analytical processes will be conducted at Diamond.
Key Techniques
Commercial pouch cells using Ni-rich cathode materials will be thoroughly analysed using a suite of electrochemical and physiochemical techniques such as high-precision battery cycling and electrochemical impedance spectroscopy. These materials will be further interrogated by XRD, Raman and XPS with scope for the synthesis of new single-crystal cathode materials.

Single crystal diffuse X-ray scattering will be analysed using 3D-delta-pair-distribution-analysis (3DDPDF) to reveal short range structural order. These probes will be used on the same samples to elucidate the local atomic movements and collective processes that underlie important phase transitions and capacity degradation.

For information on how to apply for this project please visit cdt-acm.org/phd-opportunities

Joshua Bailey

Being part of the CDT-ACM was an all-round fantastic experience; I not only received great training in a range of advanced characterisation techniques, but I also made strong links with industry and strong bonds with my cohort which have both led to fruitful collaborations.