Ann Arbor Times

A team at the University of Michigan has developed a new method for manufacturing electric vehicle (EV) batteries that could enable faster charging in cold weather. This innovation could address significant challenges currently facing EV adoption. As outlined by Neil Dasgupta, associate professor of mechanical engineering and materials science, the approach could be integrated by EV battery manufacturers without significant changes to existing production facilities.

Under typical cold temperatures, the recharging of lithium-ion batteries slows due to the reduced movement of lithium ions. To mitigate this, the team employed a modified structure and coating. According to Dasgupta, this allowed them to achieve "extreme fast charging at low temperatures, without sacrificing the energy density of the lithium-ion battery." The modifications enable these batteries to charge up to 500% faster at temperatures as low as 14 degrees Fahrenheit (-10 degrees Celsius), while maintaining 97% of their capacity after 100 fast-charging cycles.

Traditionally, demand for high power delivery has meant enlarging battery electrodes, but this compromises charging speed. In response, Dasgupta’s team previously improved charging speeds using laser-formed channels in the anode. This approach, however, was hindered by a surface layer that formed in colder environments, likened by Dasgupta to trying to cut through cold butter.

In addressing this issue, a glassy, 20-nanometer-thick coating of lithium borate-carbonate was applied to the battery. This new method in tandem with existing channels resulted in improved fast-charging performance in cold temperatures.

The changes aim to overcome challenges such as reduced range and slower charging during cold spells—issues highlighted by a drop in consumer interest in EVs. Surveys by AAA indicated a decrease in the percentage of U.S. adults likely to purchase EVs, partly due to these concerns.

Dasgupta stressed the importance of addressing long charging times, especially during winter. The new research is being advanced with support from the Michigan Economic Development Corporation. Current progress includes patent applications and collaborations to commercialize their channel technology, with Arbor Battery Innovations at the forefront.

The research team, which involved studying builds in collaboration with the Michigan Center for Materials Characterization, is working towards making their processes compatible with existing battery production lines.