Research breakthrough increases safety of lithium-ion batteries

With billions of lithium-ion batteries in circulation, safety is of paramount importance. While catastrophic Li-ion battery fires remain extremely rare, the vital work of the SafeBatt project team is ensuring that first responders know how to tackle incidents correctly and, potentially, save lives.

Project researchers Wojciech Mrozik, Paul Christensen, Paul Shearing, Julia Weaving, Martin Dowson, and Mark Buckwell were awarded the Faraday Institution Community Award for Public Engagement in 2023 in recognition of the team’s extensive engagement on battery safety with the public, first responders, and other stakeholders, giving the project an international spotlight.

The SafeBatt team collecting their Faraday community award. Left to right: Simon Moores, CEO of Benchmark Mineral Intelligence, Awards winners Julia Weaving, Wojciech Mrozik and Paul Shearing, and Faraday Institution CEO Professor Pam Thomas

The SafeBatt team collecting their Faraday Institution Community Award at the Faraday 2023 Conference

Wojciech Mrozik wearing a helmet with a contained battery fire in the background. He is simulating extreme abuse cases of lithium-ion batteries.In particular, Professor Christensen, (Professor of Pure and Applied Electrochemistry at Newcastle University) and Dr Wojciech Mrozik (Senior Research Fellow, Newcastle University), advise fire services, local authorities and other government agencies on the risks posed by Li-ion batteries and what to do in the event of an emergency.


In 2020 Paul Christensen’s team was responsible for a major breakthrough, when they highlighted the previously unknown hazard of vapour cloud explosion from Li-ion batteries in thermal runaway. When overheated, crushed or overcharged, gases can be produced in Li-ion cells and in certain circumstances their temperature can increase very suddenly. This results in the venting of a vapour cloud that includes hydrogen, carbon monoxide, carbon dioxide and very small drops of the organic solvents used in the cells. First responders had previously mistaken these clouds for steam or smoke, but their composition means they create the potential for a vapour cloud explosion, which can be more damaging than the initial fire.

By the numbers
60fire and rescue services (including internationally) that have received advice and training from Professor Christensen
113public/stakeholder engagement activities from September 2021 to June 2023
25fires per 100,000 electric car sales, compared to 1,529 per 100,000 petrol car sales (source)
£780mannual battery warranty burden in the UK for automakers by 2030. (source Faraday Institution estimate)
70%growth in e-bike sales in 2020 in the UK (source)

Since then, Professor Christensen and the team have been delivering training and guidance to first responders around the world on how to deal with these vapour clouds safely. Paul has worked with around different fire and rescue services across the UK and internationally, training hundreds of fire fighters. He has been appointed the Senior Advisor to the National Fire Chiefs Council, advises a number of UK Government steering and working groups on Li-ion safety and works as a guest instructor at the UK Fire Services College.

The team’s impact extends overseas. Professor Christensen was the recipient of the 2022 Motorola Foundations Knowledge Event Series award from the Australasian Fire and Emergency Service Authorities Council for a lecture tour of Australia, Tasmania and New Zealand organised by AFAC, the Australian fire and emergency services national council. Wojciech Mrozik visited Australia in March 2023 to present to the Safety of alternative and Renewable Energy Technologies (SARET) programme and consolidate the collaboration between SafeBatt and SARET. Both researchers are members of SARET’s Research Reference Group.

Outreach activities from across the SafeBatt project team

In total, from September 2021 to June 2023 the SafeBatt team logged an impressive 113 pieces of stakeholder engagement, including lectures, media interviews, presentations to first responder groups and membership of standards bodies, reaching thousands of people. Engagement activities include:

Wojciech Mrozik serves as a subject matter expert in Li-ion battery safety Polish Chamber of Alternative Fuels and the Polish Main Headquarters of the State Fire Service.

The team is engaged on British Standards Institute Committees including PAS 63100 (domestic energy storage systems). Team members prepared the Government’s Office for Product Safety and Standards report on the safety of second-life batteries in energy storage systems, demonstrating SafeBatt’s impact on shaping future legislation. Professor Paul Shearing, University of Oxford, SafeBatt’s Principal Investigator, is a working group member for Batteries2030 and expertise advisor to Merseyside FRS.

The Newcastle team have collaborated with fire fighters from the Durham and Darlington Fire and Rescue Service to test fire extinguishers that have been proposed for use with Li-ion batteries. The extinguishers were deployed on Li-ion batteries of a size representing typical residential battery energy storage systems.

The team engages with the wider public and industry community at conferences including the Aerospace Testing Symposium (September 2022), Battery Modelling Workshop (January 2022), IMechE’s International EV Batteries Conference (November 2022), a Royal Institution Lecture (October 2021), RISE Nordic Fire Safety Days 2022, National Chemical Emergency Centre’s event2023, and European Society for Automatic Alarm Systems Conference 2023.

Martin Dowson, WMG, supports two OEMs with battery safety investigations, advises three organisations on design of battery safety testing facilities, assists one equipment manufacturer with the development of a new calorimeter, and has run thermal runaway testing training courses for two organisations.

Julia Weaving (UCL, and Project Leader of SafeBatt), Wojciech Mrozik and Paul Christensen were lead authors for a Faraday Insight entitled “Improving the Safety of Lithium-ion Battery Cells”, the latest in a series of evidence-based assessments of the market, economics, commercial potential, and capabilities for energy storage technologies. Faraday Insights bridge knowledge gaps across industry, academia and government.

In the media, Paul Christensen acts extensively as a spokesperson on Li-ion battery fire safety, with recent coverage on BBC Radio 4, Sky News and CNBC. Dr Mark Buckwell (post-doctoral research fellow at UCL) has been interviewed for articles in Automotive World, the Wall Street Journal and The Fully Charged Show. Paul Shearing is regularly interviewed on a wide range of battery-related subject areas, including safety, including on Radio 4, a Royal Society of Chemistry Podcast and a New Scientist newsletter.

Rates of catastrophic failure in Li-ion batteries remain extremely low, with estimates suggesting that only one in 40 million suffers such a failure. But with an increasing range of use cases for Li-ion batteries, spanning electric vehicles, consumer electronics and second life applications, where existing batteries are re-conditioned and reused in new scenarios such as in the power grid, the potential for problems is increasing.

As well as protecting end users, better battery safety has economic benefits. Increasing the reliability of Li-ion battery systems could allow automakers to reduce the complexity of their systems, saving space, weight and costs. It could also cut the warranty burden on automakers, which is likely to rise to around £780m in the UK by 2030.

The Faraday Institution’s £4.3m SafeBatt project takes a broad look at the science of battery safety. Working with seven academic and two industry partners, the project has four elements; studying sub-cell level events and the interplay between degradation and safety, how cell failure propagates within a battery, modelling thermal runaway and the reaction pathways approaching cell failure and  carrying out large-scale experiments on full size battery modules and packs to observe how they behave under stress. The aim is to be able to understand these processes, which longer term will enable automakers to design and build more reliable battery packs. The SafeBatt project builds on the previous work of the Faraday Institution Degradation and ReLiB projects.

The team is expanding its research to address how to tackle vapour clouds generated by Li-ion batteries that fail in indoor settings such as tunnels and car parks, as well as residential buildings. The growing popularity of e-bikes and e-scooters is a particular concern in this respect; 170,000 of the bikes were sold in the UK in 2020, a 70% year-on-year increase. The bikes are usually fitted with Li-ion batteries, and routinely kept and charged indoors by their owners, meaning a fire could have devastating consequences, particularly in shared accommodation in urban areas where access is limited.

Professor Christensen says: “The likelihood of an electric vehicle catching fire is very low, but currently we don’t have the data on ageing batteries from cars that have been in use for a while. And as we put more and more electric vehicles on the road, there are going to be crashes, and crashes that involve electric vehicles present very different challenges for first responders.

“We are the only team doing research of this kind of breadth, and it is really vital that stakeholders across the industry know how to use these batteries safely and what to do if things go pear-shaped. This becomes particularly important as we look at more second-life use cases for Li-ion batteries.

“This is the most important work I’ve done in my career to date and it’s great to feel I’m doing something valuable and making a difference.”

Interested in learning more? Download:

Faraday Insight 17: Improving the safety of lithium-ion battery cells

P.A. Christensen et al, Risk management over the life cycle of lithium-ion batteries in electric vehicles, Renewable and Sustainable Energy Reviews, Volume 148, 111240, September 2021.

Talk by Paul Christensen, Li-ion Batteries: The Potential Hazards Facing First Responders, Newcastle University.

Case study updated September 2023.

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