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

Houston researchers have uncovered why solid-state batteries break down and what could be done to slow the process. Photo via Getty Images.

A team of researchers from the University of Houston, Rice University and Brown University has uncovered new findings that could extend battery life and potentially change the electric vehicle landscape.

The team, led by Yan Yao, the Hugh Roy and Lillie Cranz Cullen Distinguished Professor of Electrical and Computer Engineering at UH, recently published its findings in the journal Nature Communications.

The work deployed a powerful, high-resolution imaging technique known as operando scanning electron microscopy to better understand why solid-state batteries break down and what could be done to slow the process.

“This research solves a long-standing mystery about why solid-state batteries sometimes fail,” Yao, corresponding author of the study, said in a news release. “This discovery allows solid-state batteries to operate under lower pressure, which can reduce the need for bulky external casing and improve overall safety.”

A solid-state battery replaces liquid electrolytes found in conventional lithium-ion cells with a solid separator, according to Car and Driver. They also boast faster recharging capabilities, better safety and higher energy density.

However, when it comes to EVs, solid-state batteries are not ideal since they require high external stack pressure to stay intact while operating.

Yao’s team learned that tiny empty spaces, or voids, form within the solid-state batteries and merge into a large gap, which causes them to fail. The team found that adding small amounts of alloying elements, like magnesium, can help close the voids and help the battery continue to function. The team captured it in real-time with high-resolution videos that showed what happens inside a battery while it’s working under a scanning electron microscope.

“By carefully adjusting the battery’s chemistry, we can significantly lower the pressure needed to keep it stable,” Lihong Zhao, the first author of this work, a former postdoctoral researcher in Yao’s lab and now an assistant professor of electrical and computer engineering at UH, said in the release. “This breakthrough brings solid-state batteries much closer to being ready for real-world EV applications.”

The team says it plans to build on the alloy concept and explore other metals that could improve battery performance in the future.

“It’s about making future energy storage more reliable for everyone,” Zhao added.

The research was supported by the U.S. Department of Energy’s Battery 500 Consortium under the Vehicle Technologies Program. Other contributors were Min Feng from Brown; Chaoshan Wu, Liqun Guo, Zhaoyang Chen, Samprash Risal and Zheng Fan from UH; and Qing Ai and Jun Lou from Rice.

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