Even with billions of Li-ion batteries (LiBs) in circulation there are very few accidents involving them, which is testament to how safe they are. When compared to the flammability of petrol and the combustibility of diesel, LiBs pose a far lower risk of catching fire. Whilst battery fires are rare, they can occur under various conditions of mechanical, thermal or electrical stress or abuse. Operation of batteries under abnormal conditions can lead to a significant temperature rise, as well as the venting of toxic, flammable gases, which can ignite, leading to a fire.
Safety control and countermeasures are built into the design of today's LiB systems, but this adds complexity, cost and weight. As the use of LiBs expands further into automotive, stationary storage, aerospace and other sectors, there is a need to decrease the risk associated with battery usage further and to enable the simplification of safety systems. This can only be achieved through enhanced understanding of the “science of battery safety”.
This project will improve the fundamental understanding of the root causes of cell failure and the mechanisms of failure propagation. Working closely with industry partners, a multi-scale approach is being taken, from the material to the cell and module scale. This is necessary because the triggers for cell failure are varied and may result from microscopic, internal heterogeneities (e.g., lithium metal plating during charge or manufacturing defects) or from external factors, such as vehicle crash or external heating. Whilst the nucleation of failure may be a microscopic event, the propagation of failure, in particular cell-to-cell propagation, is macroscopic. Research spans time frames from the degradation of materials over hundreds of charging cycles, down to the nucleation and propagation of failure with characteristically sub-second events.
The project is also developing an improved understanding of processes occurring during real world failure, including the environmental consequences of LiB fires, which will inform the further development of fire sensing and protection systems for warehouse storage and battery energy storage systems (BESS) and help develop a consensus around the optimal method of fighting large LiB fires, be they the result of traffic collisions or at LiB recycling facilities.
The project builds from the success of an industry sprint and builds on research previously carried out in the Faraday Institution Battery Degradation and ReLiB Recycling and Reuse projects in what is a new co-ordinated research effort beginning in April 2021.
1 April 2021 – 31 March 2023
Professor Paul Shearing
Dr Julia Weaving
University of Cambridge
Imperial College London
University of Sheffield
University of Warwick
+ 2 Industry Partners
The project will: