Current flow in an electric vehicle battery

Dr Mark Bason with an electric vehicle battery in the Quantum Systems and Devices lab

Quantum physicists at the University of Sussex have used magnetic imaging for assessing electric vehicle batteries, detailed in the published peer reviewed paper. With this new technology, the researchers can visualise the inside workings of an electric vehicle battery.

The method is a radically new way of imaging current flow of a battery which can potentially highlight whether there are damaged or faulty cells. This new information means scientists could now non-invasively determine the state of health and safety of a battery.

Of particular importance in using magnetic sensors is that they are non-invasive, relatively inexpensive and track activity in real time. This can provide entirely new insights into the performance and safety of battery cells during research and development, simplify and speed up manufacture and quality control, and enable optimal and most importantly safe operation.  

The sensors work by detecting the very low magnetic fields within the battery.  To perform a scan, the battery is first placed within a magnetic shield to eliminate interference from other sources including the earth’s own magnetic field. Once the scan is performed, this is then converted into a visual image of the current flow within the battery.  Subtle differences seen in these images will allow users to detect faults in the battery.

The rapid pace of replacing fossil fuel transport with electric vehicles is critically dependent on high-performing, high energy density and efficient batteries. These developments can considerably support realising the proposals set by the UK government to ban the sales of all new petrol and diesel cars by 2030.

Dr Mark Bason, lead author of the paper explains: “Our research opens the doors for some truly exciting possibilities within the transportation sector and the possibility of battery MOTs as part of a regular maintenance schedule for electric cars. 

“We measure current flows during charge and discharge cycles. The distribution of the current could indicate the state of health and safety of the battery.  When looking at the current flow we can see small differences in the image taken depending on these factors.

“In the future we imagine battery MOTs to take place where the sensors are used in a predefined sequence such as charging the battery from half full. With up to 100 batteries in a vehicle, mechanics would perhaps look at points that are likely to be troublesome or that would typically require more maintenance such as batteries in positions most likely to overheat.  With the information gleaned from using the sensors they should be able to detect where batteries are going wrong before they become unsafe.”

Professor Peter Krüger, Principal Investigator of the Quantum Systems and Devices group says “We want to develop quantum technologies to be used for a more sustainable future.  Reliable, efficient and workable energy storage is crucial for the electrification of transport.  We must consider what we do when batteries are no longer fit for purpose and the most planet friendly outcome.  Using quantum technology to develop a sensor that can prevent a battery being discarded unnecessarily could be significant in the global challenge to ensure mainstream electrification of transport.  Developing these new technologies is hugely rewarding and where I believe we should be harnessing the power of quantum physics.”

The full peer reviewed paper Non-invasive Current Density Imaging of Lithium-Ion Batteries can be read in the Journal of Power Sources.

The development was made possible thanks to funding from Innovate UK, and is a result of a collaboration with CDO2, an industrial partner based at the Sussex Innovation Centre at the University of Sussex.

The University of Sussex, which aims to become one of the world’s most sustainable universities, launched its Sustainable Sussex strategy in 2021.

Further information: https://www.sussex.ac.uk/research/centres/quantum-systems-and-devices/