Scientists have developed a lithium ion battery which could potentially add 200 miles of driving range to an electric car in just 10 minutes.
According to the Pennsylvania State University researchers, this is achieved by charging at a higher temperature to increase reaction rate, but keeping the cell cool during discharge.
If brought into production, the design is one potential strategy to alleviate concerns surrounding ‘range anxiety’ which 100% electric vehicles face on long journeys. The researchers presented the work on 30 October in the journal Joule.
Scientists have recognised the need to design electric vehicle batteries capable of charging extremely fast in order to meet the needs of drivers. However, such a speedy charge rate would require a battery to rapidly take in 400 kilowatts of energy, a feat that current vehicles cannot accomplish because it risks lithium plating (the formation of metallic lithium around the anode), which would severely deteriorate battery life.
While conventional lithium batteries are charged and discharged at the same temperature, the researchers found they could circumvent the lithium plating issue by charging the battery to an elevated temperature of 60 degrees Celsius for a few minutes, then discharging it at cooler temperatures.
"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," says senior author Chao-Yang Wang, a mechanical engineer at The Pennsylvania State University.
"The key is to realize rapid heating; otherwise, the battery will stay at elevated temperatures for too long, causing severe degradation.
"In the past, it was universally believed that lithium ion batteries should avoid operating at high temperatures due to the concern of accelerated side reactions," says Wang. "This study suggests that the benefits of mitigated lithium plating at the elevated temperature with limited exposure time far outweigh the negative impact associated with exacerbated side reactions."
The researchers say that the technology is completely scalable because all the cells are based on industrially available electrodes; and they have already demonstrated its use in large-scale cells, modules, and battery packs. The nickel foil increases the cost of each cell by 0.47%, but because the design eliminates the need for the external heaters used in current models, it actually lowers the cost of producing each pack.
Image credit: Chao-Yang Wang Group