There is never a lack of news regarding battery advancements. It seems like there is always something new and fascinating occurring in the sector, from a battery design that might last up to 100 years to a water-based battery that is created at half the cost of lithium-ion ones.
Now, engineers at the University of California, San Diego, have engineered novel energy-packed lithium-ion batteries that perform optimally at freezing cold and scorching hot temperatures, according to a statement by the institution released on Monday.
Operations at extreme temperatures
“You need high-temperature operation in areas where the ambient temperature can reach the triple digits and the roads get even hotter. In electric vehicles, the battery packs are typically under the floor, close to these hot roads,” explained Zheng Chen, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering and senior author of the study.
“Also, batteries warm up just from having a current run through during operation. If the batteries cannot tolerate this warmup at high temperature, their performance will quickly degrade.”
Chen’s team ran tests with the prototype batteries and found that they retained 87.5% and 115.9% of their energy capacity at -40 and 122 F (-40 and 50 C ), respectively. Better yet, the researchers reported that the prototypes had high Coulombic efficiencies of 98.2% and 98.7% at these temperatures, which means the batteries can undergo more charge and discharge cycles before they cease to function.
However, developing the new batteries was no easy task.
“If you want a battery with high energy density, you typically need to use very harsh, complicated chemistry,” said Chen. “High energy means more reactions are happening, which means less stability, more degradation. Making a high-energy battery that is stable is a difficult task itself—trying to do this through a wide temperature range is even more challenging.”
Engineering a dibutyl ether electrolyte
In order to bypass these hurdles, the team invented a dibutyl ether electrolyte and engineered the sulfur cathode to be more stable by grafting it to a polymer preventing more sulfur from dissolving into the electrolyte.
The end result was batteries with much longer cycling lives than a typical lithium-sulfur battery. “Our electrolyte helps improve both the cathode side and anode side while providing high conductivity and interfacial stability,” said Chen.
The new batteries could now enable electric vehicles to travel further on a single charge in cold climates while also alleviating the need for cooling systems to keep the vehicles’ battery packs from overheating in hot climates. But first, the team needs to scale up the battery chemistry, optimize it to work at even higher temperatures, and further extend its cycle life.
The study is published in the Proceedings of the National Academy of Sciences (PNAS).
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