The Faraday Institution is composed of several large consortia who aim for the UK to become the international hub for electrical energy-based research. Chaired by Prof. Clare Grey at the University of Cambridge, the degradation project research is spread across collaborators at numerous institutions including the Universities of Southampton, Oxford, Warwick, Liverpool, Manchester, UCL, Imperial, Sheffield and Newcastle University.
The ultimate goal of the degradation project is to better understand the processes that cause battery degradation that eventually leads to battery failure. A wide range of techniques are used across the consortium to characterise properties associated with battery failure such as the anode solid electrolyte interphase (SEI) layer, the bulk structure of Ni-rich cathodes etc. and how these change with prolonged cycling. This knowledge is paramount for the rational design of stable high energy density batteries with long lifetimes. In order to obtain the most accurate and unambiguous information, studying systems as they are cycling (operando) is considered the most ideal set-up, thus a large number of developments and experiments within the consortium are using specialised cells to probe certain characteristics of the batteries. Working alongside the characterisation project, we are aiming to develop and implement operando cells to study the chemical evolution in battery systems using surface sensitive techniques such as X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), total electron yield X-ray absorption spectroscopy (TEY-XAS) and hard X-ray photoelectron spectroscopy (HAXPES). Meanwhile the operando techniques are being developed, the surface sensitive techniques are being used for characterization of ex-situ samples for identification of chemical changes on the electrodes depending on cycling conditions.
These x-ray spectroscopy techniques will be complimented with ex-situ photoemission electron microscopy (PEEM) and scanning probe microscopy techniques such as conductive atomic force microscopy (AFM) and electrochemical strain microscopy (ESM) providing high resolution spatiochemical information. By application of these techniques we aim to map the changing chemical and structural environment, along with the ionic and electronic conductivity of the materials as they age with electrochemical cycling. Information gained from these techniques will be used for new material and battery cell designs to mitigate the impact of these degradation mechanisms hindering the use of next generation battery materials.