Engineers track exploding lithium-ion batteries
28 Apr 2015
A team of engineers led by University College London (UCL) has tracked what happens when lithium-ion batteries overheat and explode.
The UCL-led team used high-energy synchrotron X-rays and thermal imaging to understand exactly what takes place both on the inside and outside of batteries when exposed to extreme levels of heat.
“We needed exceptionally high speed imaging to capture ’thermal runaway’ - where the battery overheats and can ignite,” said study leader Donal Finegan, a UCL chemical engineering graduate.
“Our results show how useful our method is in tracking battery damage in 3D and in real-time
UCL chemical engineer Paul Shearing
“This was achieved at the ESRF (European Synchrotron Radiation Facility) beamline ID15A where 3D images can be captured in fractions of a second thanks to the very high photon flux and high speed imaging detector.”
The study, which also included scientists from Imperial College London (ICL) and the National Physical Laboratory, shows for the first time how internal structural damage to batteries evolves in real-time, and provides an indication of how this can spread to neighbouring batteries.
Understanding how lithium-ion batteries fail and potentially cause a dangerous chain reaction of events is important for improving their design to make them safer to use and transport, claim the engineers behind the study.
The team looked at the effects of gas pockets forming, venting and increasing temperatures on the layers inside two distinct commercial lithium-ion batteries as they exposed the battery shells to temperatures in excess of 250 degrees C.
“Although we only studied two commercial batteries, our results show how useful our method is in tracking battery damage in 3D and in real-time,” said corresponding author Paul Shearing.
“The destruction we saw is very unlikely to happen under normal conditions as we pushed the batteries a long way to make them fail by exposing them to conditions well outside the recommended safe operating window,” Shearing said.
“This was crucial for us to better understand how battery failure initiates and spreads. Hopefully from using our method, the design of safety features of batteries can be evaluated and improved.”
Looking ahead, the team will attempt to study what happens with a larger sample size of batteries and in particular, they will investigate what changes at a microscopic level lead to widespread battery failure.
The study was funded by the Royal Academy of Engineering, the Engineering and Physical Sciences Research Council and National Physical Laboratory, and will appear in the journal Nature Communications today.
