University of Michigan cracks rapid EV charging in freezing temps

Charging your EV in freezing weather could soon become dramatically faster, thanks to a big breakthrough from the University of Michigan engineers.

Neil Dasgupta, U-M associate professor of mechanical engineering and materials science and engineering and corresponding author of a study published in Joule, and his team have developed an innovative battery structure and coating that can boost lithium-ion EV battery charging speeds by a whopping 500%, even at frigid temperatures as low as 14F (-10C). “Charging an EV battery takes 30 to 40 minutes even for aggressive fast charging, and that time increases to over an hour in the winter,” Dasgupta explained. “This is the pain point we want to address.”

Freezing weather has traditionally been harsh on EV batteries because it slows down the movement of lithium ions, resulting in slower charging speeds and reduced battery life. Automakers have tried thickening battery electrodes to extend driving range, but this makes some of the lithium hard to access, making charging even slower.

Previously, Dasgupta’s group sped up battery charging using lasers to carve pathways around 40 microns in size into the graphite anode. This allowed lithium ions to reach deeper into the battery more quickly. However, cold-weather performance still lagged because a chemical layer formed on the electrodes, blocking the ions. Dasgupta compares this barrier to “trying to cut cold butter,” making charging inefficient.

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To solve this, the team coated the battery with a thin, glassy material made of lithium borate-carbonate—only 20 nanometers thick—which prevented the problematic chemical layer from forming. Combined with the microscopic channels, the results were groundbreaking: the modified batteries retained 97% of their capacity even after 100 fast-charging cycles in freezing temperatures.

“We envision this approach as something that EV battery manufacturers could adopt without major changes to existing factories,” Dasgupta noted. “For the first time, we’ve shown a pathway to simultaneously achieve extreme fast charging at low temperatures, without sacrificing the energy density of the lithium-ion battery.”

This innovation could tackle one of the biggest concerns holding potential EV buyers back.

The new battery tech is moving closer to commercialization, supported by the Michigan Economic Development Corporation’s Michigan Translational Research and Commercialization (MTRAC) Advanced Transportation Innovation Hub. The research devices were built at U-M’s Battery Lab and studied with help from the Michigan Center for Materials Characterization.

U-M Innovation Partnerships assisted the team in applying for patents, and Arbor Battery Innovations has licensed the technology for market deployment. Dasgupta and the University of Michigan hold financial stakes in Arbor Battery Innovations.

Read more: California now has nearly 50% more EV chargers than gas nozzles

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