A new testing technique has revealed Li-ion batteries can be safely charged much faster than current manufacturers’ recommendations
A group of researchers from the University of Warwick in the UK have discovered that commercially available Lithium-ion batteries can be safely charged five times faster than currently recommended.
The group used commercially available 18650 battery cells to measure the maximum charging current that would be considered safe. Using thermal sensors, the team evaluated the level of charging current that can be used before temperature increases in the cell can be considered dangerous or damaging to the battery.
The study recognised the growing consumer need for faster charging in EVs, alongside other applications, however also considered the damaging “significant impact” on cycle life, thermal performance and safety” that faster charging could have on the battery.
Through studies, they determined that the maximum charging current that could be used was dramatically higher -by some 6.7 times – than current manufacturer recommendations. The researchers successfully tested the safety of a ‘rapid charging profile’, which allowed for charging rates five times faster than current recommendations, without overheating the battery which can cause severe damage or catastrophic failure.
The results open up new questions around the future development of battery technology and charging power.
Limitations of rapid charging
While the results suggest that li-ion batteries can be safely charged five times faster than recommended, the authors also recognised the “somewhat adverse effect on the cell long-term capacity retention if used as the main charging protocol,” – meaning that this faster charging option cannot be recommended to be used all the time as it leads to the faster deterioration of the battery and its life cycle.
Nevertheless lead researcher, Dr. Tazdin Amietszajew, addressed the positive impact such flexibility could afford EV users:
“Faster charging as always comes at the expense of overall battery life, but many consumers would welcome the ability to charge a vehicle battery quickly when short journey times are required and then to switch to standard charge periods at other times.”
Most importantly, the study argued for the importance of the development of technology which can better monitor internal cell temperature and charging potentials. They argue this will not only allow for faster charging but also minimise the damaging effect that faster charging can have on batteries life cycles.
The ability to charge commercially li-ion batteries up to five times faster is certainly an exciting prospect for EV users – and precludes the need for a step-change in either battery architecture or technology. Yet, as using the rapid charging option is not viable for constant use, it also emphasises the need for better battery management systems and the necessary infrastructure to allow for variable charging rates before this becomes a possibility for every day usage.