Rice University researchers have uncovered a more energy-efficient and faster way to recycle critical minerals from used lithium-ion batteries.

Traditional methods rely on high heat, long processing times and harsh chemicals to recover a small fraction of critical materials from batteries used in everything from smartphones to electric vehicles. However, the team from Rice's Department of Materials Science and Nanoengineering developed a process that uses a water-based solution containing amino chlorides to extract more metals in less time

The team published the findings in a recent edition of the scientific journal Small.

Simon King, a sophomore studying chemical and biomolecular engineering who completed this work as a summer research fellow at the Rice Advanced Materials Institute, served as first author of the study. He worked with corresponding authors Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor of Engineering, and Sohini Bhattacharyya, a research scientist in Ajayan’s lab.

By using a hydroxylammonium chloride (HACI) solution, the team achieved roughly 65 percent extraction of key battery metals in just one minute at room temperature, according to the study. The efficiencies grew to roughly 75 percent for several metals under longer processing times.

“We were surprised by just how fast the reaction occurs, especially without the involvement of high temperatures,” King said in a news release. “Within the first minute, we’re already seeing the majority of the metal extraction take place.”

By not requiring high temperatures or long reaction times, Rice predicts the process could have a major impact on cost and the environmental impact of lithium battery recycling. Additionally, the water-based HACI solution makes waste handling easier and lowers certain environmental risks.

In addition to extracting the materials, the team went on to demonstrate that the recovered metals could be recycled and reprocessed into new battery materials.

“A big advantage of this system is that it works under relatively mild conditions,” Ajayan added in the release. “That opens the door to more sustainable and scalable recycling technologies.”