Engineer, Aileen Sartor, considers the complex challenges around lithium-ion battery re-use.
Year on year a growing number of battery electric vehicles have been sold, as we transition towards Net Zero. Like lithium-ion batteries in other applications, their capacity degrades over time. However, unlike the mild inconvenience of your depleted phone battery running out of charge, it’s a much bigger problem if the battery in your electric vehicle doesn’t allow you to travel very far on a single charge. Consequently, these batteries will need replacement during the vehicle’s lifetime, and it is estimated this could be every 10-20 years[1].
But what is the plan for all the old batteries?
You could simply dispose of the batteries, but that is not very environmentally friendly, and doesn’t align with a circular economic approach. Alternatively, you could recycle the battery. However, the safety challenges associated with disassembling the battery, and the fact that the recycling process is more expensive than the materials you recover[2] means this is not an attractive option either.
The third option is to reuse the battery in a different application – a ‘second life’ battery. Second life batteries are being considered for stationary applications, which would involve using a big lithium-ion battery to support operation of the electricity network. However, there are still several challenges for using old electric vehicle batteries in such roles:
- How can battery cells with different levels of degradation, from different manufacturers, with different designs, sizes and chemistries be aggregated to form a larger stationary installation?
- What are the safety risks associated with using batteries with existing degradation in a different application?
- What are the considerations when designing the control system for the aggregated cells?
Further research will be required to overcome the technical challenges, and standards will need to be developed to ensure the operation of these second life batteries is both safe and reliable.
[1] https://www.edfenergy.com/electric-cars/batteries#:~:text=Electric%20car%20battery%20technology&text=This%20decreases%20the%20range%20and,they%20need%20to%20be%20replaced.
[2] https://es.catapult.org.uk/report/storage-and-flexibility-net-zero-series-second-life-batteries/