Thermal Runaway Processes in Li-ion Batteries

1. Brief description of the context of the research including potential impact;
Understanding the safe implementation of advanced batteries in automotive applications is critical to the decarbonisation of the transport sector in support of Net Zero ambitions, and the automotive industry's strategy for electrification. Whilst the failure of batteries is rare, the risk of thermal runaway (a catastrophic failure event), which can trigger cell-to-cell failure propagation requires further understanding for effective risk management.
In this project we will develop and apply experimental and modelling tools to quantity thermal runaway in Li-ion batteries to advance their safe deployment in automotive and other applications.

2. Aims and objectives;
Over the past decade, we have developed a suite of tools for advanced failure analysis, which include X-ray imaging, thermography, acoustic sensing and calorimetry - these can be applied in concert to elucidate failure mechanisms under thermal, mechanical and electrical abuse scenarios. These tools have principally been applied to cylindrical cell geometries, where extensive foundation work has been undertaken to explain the nucleation and propagation of failure. However, the next generation of automotive batteries are likely to be larger format prismatic cells assembled in a 'cell to pack' configuration.
In this project we will extend the tools from cylindrical to pouch cell configuration; this is highly non-trivial given the different failure mechanisms expected, the physically larger cell size (limiting probe access) and the more energetic failures that may result.

Our approach will be two-fold; firstly we will develop new experimental tools to elucidate the 'state-of-safety' of these large format cells using correlative thermal, structural and acoustic probes. Secondly, we will develop new cell failure models; these will be validated against the large available data library for cylindrical cells and provide a viable means for translation of safety data from small to larger cell formats. In combination, this will develop a platform for comprehensive failure evaluation, providing new insight into the fundamental mechanisms of thermal runaway which can be utilised to engineer effective mitigation strategies, and to understand and inform the emerging international standards framework for cell and pack qualification.

3. Novelty of the research methodology;

Whilst the development of safety certification tools for automotive batterie is well developed, there is a critical need for development of advanced laboratory tools to understand the science of battery safety. Moreover, the simulation environments for modelling these complex processes remains immature. There is therefore a significant novelty to the development of this combined modelling and experimental research methodology.

4. For EPSRC: alignment to EPSRC's strategies and research areas (which EPSRC research area the project relates to).

'This project falls within the EPSRC Energy research area' where Energy Storage is one of the themes or research areas listed:
"Energy storage The study of materials and systems which store electrochemical, thermal or kinetic energy for later use."

5. Any companies or collaborators involved.

A major UK OEM are the industry sponsors of this iCASE award.