Project Overview

The performance of battery materials is dictated by the stability, efficiency and functionality of their interfaces, i.e. the solid electrolyte interphase (SEI) at the anode and oxygen-induced cathode-electrolyte interface (CEI) at cathode. Attempts to analyse these interfaces in order to determine their structure and chemistry is complicated by the extreme air-sensitivity, beam sensitivity and the high volatility of certain species present.

In order to address these issues WMG is in the process of procuring a specially configured characterisation tool for characterasing these critical interfaces in battery materials that consists of a Plasma Focussed Ion Beam (PFIB) microscope equipped with airless transfer and cryo capability.

In this project extensive use will be made of this new system to develop strategies for studying the degradation of buried interfaces and structure dynamics in state-of-the-art high Ni NMC cathodes as a function of cycle ageing i.e. the evolution of the CEI. The system provides some unique opportunities for developing powerful new ways to characterise these controlling interfaces and this will form the basis of this project. The specific objective of the projects are:

· Define the capabilities of both Time-of-Flight SIMS and quadrupole SIMS for studying SEI layers in battery materials. SIMS is the only way to detect and map Li in bulk samples in an electron microscope. The AMMC microscopy centre at WMG is the only centre in the world to contain both types of SIMS detector in the same facility (to the best of our knowledge). This project will allow the capabilities of both flavours of SIMS (which have significant technical differences) for studying SEI to be systematically mapped.

· The SIMS work will be extended by cooling the sample to cryogenic temperatures for the ToF SIMS analysis. This will be invaluable for probing both liquid and solid electrolyte batteries. The reduced species volatility and improved vacuum at low temperatures (known to improve ion yield) is expected to yield new capabilities.

· The SIMS work will be further extended to assess the effect of ion species. The new PFIB contains a multi-species ion source, which also provides new possibilities for the SIMS analysis of many types of layers and interfaces/interphases, which will also be explored in this project.

Applicants should have qualified with, or expect to obtain, an upper second-class bachelor’s degree in material science, engineering, physics or chemistry. A relevant master's degree and/or equivalent practical experience will be an advantage. Excellent English written and spoken communication skills, self-motivatation and excellent time-management skills are also required.