Simple, Energy-Efficient Recycling Process for Lithium-Ion Batteries

A new recycling process requires half the energy of conventional techniques and produces ready-to-use cathode materials

2 min read
Used cathode particles from spent lithium ion batteries are recycled and regenerated to work as good as new.
Photo: David Baillot/UC San Diego Jacobs School of Engineering

A simple new recycling process restores old lithium battery cathodes to mint condition using half the energy of current processes. Unlike today’s recycling methods, which break down cathodes into separate elements that have to be put together again, the new technique spits out compounds that are ready to go into a new battery.

The method works on the lithium cobalt oxide batteries used in laptops and smartphones, and also on the complex lithium-nickel-manganese-cobalt batteries found in electric cars.

Lithium batteries have anodes made of graphite and cathodes made of lithium metal oxides, where the metal is some combination of cobalt, nickel, manganese, and iron. Less than five percent of old lithium batteries are recycled today. As millions of large EV batteries retire in the next decade, we’re going to send even bigger mountains of flammable, toxic battery waste to landfills. Plus, that waste contains valuable metals. There is serious concern that supplies of critical metals like cobalt and lithium are dwindling. Recycling is going to be key if we’re to keep up with battery demand.

Several companies, mostly in China, already reprocess batteries. The standard procedure requires crushing batteries, and then either melting them or dissolving them in acid. What comes out at the end is separate metals like cobalt, lithium, nickel, and manganese. In addition to using intense amounts of energy, the methods destroy what’s most valuable about battery cathodes, says Zheng Chen, a professor of nanoengineering at the University of California, San Diego.

“The material is in the form of beautiful, well-designed particles with a specific microscopic structure that determines the performance of the battery,” he says. “A lot of engineering, energy, and time go into making these structures.”

The simple method Chen and his colleagues developed preserves that microstructure. The researchers first cycled commercial lithium cells until they had lost half their energy storage capacity. They removed the cathode material from their aluminum foil substrate, and soaked it in a hot lithium salt bath. Then they dried the solution to get powder, which they quickly heated to 800 degrees C and then cooled down very slowly.

The process restores the cathode material’s atomic structure and re-injects lithium ions into it. And it uses half the energy of conventional processes. The researchers made new battery cells with the regenerated cathode material. The new cathodes showed the same energy storage capacity, charging time, and lifetime as the originals. The results are reported in the journal Green Chemistry.

Two other companies have been pursuing a similar “direct recycling” technology that regenerates the entire structured cathode material. San Francisco-based battery company Farasis Energy and Bend, Oregon startup OnTo Technologies are both developing the technology and trying to scale it up. The processes are all slightly different from each other.

The more players in the space, the better, says Linda Gaines, a transportation systems analyst at Argonne National Laboratory. The chemistry and cell design of today’s lithium-ion batteries are evolving quickly. “Direct recycling technologies could enable recovery of high-value product from newer battery formulations,” she says.

But one of the biggest challenges it faces is finding better ways to separate the cathode material from the rest of the battery—Chen and his team do this manually—and show that the process is economical on a large scale.

Chen is now refining his process so it can be used for any lithium battery material. He is also in talks with a Chinese battery processing company that is interested in adopting the new recycling method.

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Smokey the AI

Smart image analysis algorithms, fed by cameras carried by drones and ground vehicles, can help power companies prevent forest fires

7 min read
Smokey the AI

The 2021 Dixie Fire in northern California is suspected of being caused by Pacific Gas & Electric's equipment. The fire is the second-largest in California history.

Robyn Beck/AFP/Getty Images

The 2020 fire season in the United States was the worst in at least 70 years, with some 4 million hectares burned on the west coast alone. These West Coast fires killed at least 37 people, destroyed hundreds of structures, caused nearly US $20 billion in damage, and filled the air with smoke that threatened the health of millions of people. And this was on top of a 2018 fire season that burned more than 700,000 hectares of land in California, and a 2019-to-2020 wildfire season in Australia that torched nearly 18 million hectares.

While some of these fires started from human carelessness—or arson—far too many were sparked and spread by the electrical power infrastructure and power lines. The California Department of Forestry and Fire Protection (Cal Fire) calculates that nearly 100,000 burned hectares of those 2018 California fires were the fault of the electric power infrastructure, including the devastating Camp Fire, which wiped out most of the town of Paradise. And in July of this year, Pacific Gas & Electric indicated that blown fuses on one of its utility poles may have sparked the Dixie Fire, which burned nearly 400,000 hectares.

Until these recent disasters, most people, even those living in vulnerable areas, didn't give much thought to the fire risk from the electrical infrastructure. Power companies trim trees and inspect lines on a regular—if not particularly frequent—basis.

However, the frequency of these inspections has changed little over the years, even though climate change is causing drier and hotter weather conditions that lead up to more intense wildfires. In addition, many key electrical components are beyond their shelf lives, including insulators, transformers, arrestors, and splices that are more than 40 years old. Many transmission towers, most built for a 40-year lifespan, are entering their final decade.

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