Researchers Led by WPI’s Yan Wang Develop Solvent

A team led by Worcester Polytechnic Institute (WPI) researcher Yan Wang has developed a solvent-free process to manufacture lithium-ion battery electrodes that are greener, cheaper, and charge faster than electrodes currently on the market, an advance that could improve the manufacturing of batteries for electric vehicles.

In the journal Joule, the group reported on a dry-print manufacturing process that avoids the toxic solvents and the long drying times needed when manufacturing electrodes with slurries and conventional production methods. Wang, who is the WPI William B. Smith Dean's Professor in the Department of Mechanical and Materials Engineering, said the new process could be scaled up and reduce electrode manufacturing costs by up to 15 percent, while also producing electrodes that can charge faster than conventionally produced electrodes.

"Current lithium-ion batteries charge too slowly, and manufacturers typically use flammable, toxic, and expensive solvents that increase the time and cost of production," Wang said. "Our solvent-free manufacturing process addresses those disadvantages by producing electrodes that charge to 78 percent of capacity in 20 minutes, all without the need for solvents, slurries, and long production times."

Commercial lithium-ion battery electrodes are typically made by mixing active materials, conductive additives, polymers, and organic solvents to create a slurry that is pasted onto a metal substrate, dried in an oven, and cut into pieces for use in batteries. The solvents are recovered through distillation.

The researchers’ process, in contrast, involved mixing together dry powders that were electrically charged so they would adhere when sprayed onto a metal substrate. The dry-coated electrodes were then heated and compressed with rollers. Skipping the conventional drying and solvent-recovery process cut battery manufacturing energy use by an estimated 47 percent, the researchers reported.

Wang has long been focused on improving lithium-ion batteries and reducing the waste they create. He co-founded Ascend Elements, a company that is developing battery recycling technologies. Wang's electrode manufacturing work has been funded by the Department of Energy with the United States Advanced Battery Consortium LLC and the Massachusetts Clean Energy Center. Collaborators on the project included Yangtao Liu ’22 (PhD), graduate student Jinzhao Fu, Assistant Research Professor Xiaotu Ma, Panawan Vanaphuti ’22 (PhD), and Rui Wang ’23 (PhD), all of WPI; and researchers at Texas A&M University, Rice University, Microvast Inc., Argonne National Laboratory, and Brookhaven National Laboratory.

WPI has filed a patent application on the manufacturing technology developed by Wang's team. In addition, Wang and one of his collaborators, Heng Pan of Texas A&M University, co-founded AM Batteries Inc., a venture-backed company that is working with Amperex Technology Limited (ATL) and other companies to scale up solvent-free electrode manufacturing.

Worcester Polytechnic Institute will lead a team of industry and university researchers in a $2.4 million project to manufacture cheaper, faster-charging lithium-ion car batteries.

Yan Wang, a globally recognized materials researcher, is one of 83 of the "world's best emerging academic inventors" elected to the National Academy of Inventors 2022 class.

Worcester Polytechnic Institute (WPI) will expand its work on lithium-ion battery recycling and lead a team of academic and industry collaborators in a $2 million project to lower the cost and improve the performance of recycled battery materials.

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