researching for the future

Houston scientists discover breakthrough process for lithium-ion battery recycling

The Rice team's process is up to 10 times more effective than existing lithium-ion battery recycling. Photo by Gustavo Raskosky/Rice University

With the rise of electric vehicles, every ounce of lithium in lithium-ion batteries is precious. A team of scientists from Rice University has figured out a way to retrieve as much as 50 percent of the material in used battery cathodes in as little as 30 seconds.

Researchers at Rice University’s Nanomaterials Laboratory led by Department of Materials Science and NanoEngineering Chair Pulickel Ajayan released the findings a new study published in Advanced Functional Materials. Their work shows that the process overcomes a “bottleneck” in lithium-ion battery recycling technology. The researchers described a “rapid, efficient and environmentally friendly method for selective lithium recovery using microwave radiation and a readily biodegradable solvent,” according to a news release.

Past recycling methods have involved harsh acids, and alternative eco-friendly solvents like deep eutectic solvents (DESs) at times have not been as efficient and economically viable. Current recycling methods recover less than 5 percent of lithium, which is due to contamination and loss during the process.

In order to leach other metals like cobalt or nickel, both the choline chloride and the ethylene glycol have to be involved in the process, according to the researchers at Rice. The researchers submerged the battery waste material in the solvent and blasted it with microwave radiation since they knew that of the two substances only choline chloride is good at absorbing microwaves.

Microwave-assisted heating can achieve similar efficiencies like traditional oil bath heating almost 100 times faster. Using the microwave-based process, Rice found that it took 15 minutes to leach 87 percent of the lithium, which differs from the 12 hours needed to obtain the same recovery rate via oil bath heating.

“This method not only enhances the recovery rate but also minimizes environmental impact, which makes it a promising step toward deploying DES-based recycling systems at scale for selective metal recovery,” Ajayan says in the release.

Due to rise in EV production, the lithium-ion battery global market is expected to grow by over 23 percent in the next eight years, and was previously valued at over $65 billion in 2023.

“We’ve seen a colossal growth in LIB use in recent years, which inevitably raises concerns as to the availability of critical metals like lithium, cobalt and nickel that are used in the cathodes,” the study's co-author, Sohini Bhattacharyya, adds. “It’s therefore really important to recycle spent LIBs to recover these metals.”

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A View From HETI

A team at the University of Houston is changing the game for sodium-ion batteries. Photo via Getty Images

A research lab at the University of Houston has developed a new type of material for sodium-ion batteries that could make them more efficient and boost their energy performance.

Led by Pieremanuele Canepa, Robert Welch assistant professor of electrical and computer engineering at UH, the Canepa Research Laboratory is working on a new material called sodium vanadium phosphate, which improves sodium-ion battery performance by increasing the energy density. Energy density is the amount of energy stored per kilogram, and the new material can do so by more than 15 percent. With a higher energy density of 458 watt-hours per kilogram — compared to the 396 watt-hours per kilogram in older sodium-ion batteries — this material brings sodium technology closer to competing with lithium-ion batteries, according to the researchers.

The Canepa Lab used theoretical expertise and computational methods to discover new materials and molecules to help advance clean energy technologies. The team at UH worked with the research groups headed by French researchers Christian Masquelier and Laurence Croguennec from the Laboratoire de Reáctivité et de Chimie des Solides, which is a CNRS laboratory part of the Université de Picardie Jules Verne, in Amiens France, and the Institut de Chimie de la Matière Condensée de Bordeaux, Université de Bordeaux, Bordeaux, France for the experimental work on the project.

The researchers then created a battery prototype using the new materia sodium vanadium phosphate, which demonstrated energy storage improvements. The material is part of a group called “Na superionic conductors” or NaSICONs, which is made to let sodium ions move in and out of the battery during charging and discharging.

“The continuous voltage change is a key feature,” Canepa says in a news release. “It means the battery can perform more efficiently without compromising the electrode stability. That’s a game-changer for sodium-ion technology.”

The synthesis method used to create sodium vanadium phosphate may be applied to other materials with similar chemistries, which could create new opportunities for advanced energy storage. A paper of this work was published in the journal Nature Materials.

"Our goal is to find clean, sustainable solutions for energy storage," Canepa adds. "This material shows that sodium-ion batteries can meet the high-energy demands of modern technology while being cost-effective and environmentally friendly."

Pieremanuele Canepa, Robert Welch assistant professor of electrical and computer engineering at UH, is leading a research project that can change the effectiveness of sodium-ion batteries. Photo courtesy of UH

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