New method overcomes main obstacle to extreme fast charging, Lithium plating, which happens at high charge rates and significantly reduces battery life
A new research promises to quicken the process of charging the lithium ion batteries (LiB) that power electric vehicles, (EVs).
An EV can travel a maximum 150-200 kilometres (km) on a single charge. But charging requires at least 30-40 minutes. While an AC charger takes around six hours to power an EV, DC chargers are faster and take around 40 minutes to one hour to fully charge a car.
Even fast-charging options on luxury cars like the Mercedes-Benz EQC need a minimum of 30-40 minutes to charge the batteries up to 80 per cent.
The US Department of Energy has set a goal of developing extreme fast charging (XFC) technology that can add 200 miles of driving range in 10 minutes, but the main obstacle to XFC is Lithium (Li) plating, which happens at high charge rates and significantly reduces battery life.
To circumvent the problem, researchers from Pennsylvania State University developed a asymmetric temperature modulation (ATM) method that charges an LiB at an elevated temperature of 60 degrees Celsius to eliminate Li plating and limits the exposure time at 60°C to only 10 minutes per cycle to prevent serious materials degradation.
The ATM method enables XFC of LiB with an excellent life cycle, while substantially reducing battery cooling needed during XFC.
“In addition to fast charging, this design allows us to limit the battery's exposure time to the elevated charge temperature, thus generating a very long cycle life,” senior author of the study Chao-Yang Wang, a mechanical engineer at the university, was quoted as saying by the journal Cell.
“The key is to realise rapid heating; otherwise, the battery will stay at elevated temperatures for too long, causing severe degradation,” the researcher added.
LiBs, it was earlier believed, should avoid operating at high temperatures due to the worry of accelerated materials degradation.
The scientific merit of the ATM method is that it offers a solution to speed up electrochemical processes like enhancing kinetics and transport while still effectively managing materials degradation.
The ATM method has hopefully opened a new path for designing electrochemical energy systems that can achieve high performance and long life simultaneously.
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