Recycle, Recharge, Reuse

New recycling method could offset battery waste of the future.

Electric vehicles may someday make gas-guzzling emissions a thing of the past, but they will eventually leave behind a different by-product to reckon with: millions of tons of spent lithium-ion batteries.

Without efficient or economical battery recycling systems in place, less than 5 percent of the lithium-ion batteries around the world are currently recycled. As these batteries get tossed, so do valuable metals like cobalt, an essential component that also comes with serious environmental and ethical costs. Half of the world’s cobalt is mined in the Democratic Republic of Congo, for instance, where hazardous conditions and child labor have been reported.

This makes efficient battery recycling a critical issue, one that UC San Diego researchers are determined to tackle with methods that could give these batteries new life and keep them out of landfills.

Materials in modern batteries have proven difficult to recycle, but nanoengineer Zheng Chen (left) and postdoc Yang Shi have developed an efficient method.

Nanoengineers at the Jacobs School of Engineering’s Sustainable Power and Energy Center have devised a novel way to recycle lithium-ion batteries piece by piece—starting with the cathode, or the positive side of the battery, in which the most cobalt is used. The process can restore cathodes to near-mint condition and is viable for not just electric vehicle batteries but also those used in laptops, smartphones, tablets and digital cameras.

The method was developed in the lab of nanoengineering professor Zheng Chen and uses a chemical bath and sound-wave technology to break the lithium-cobalt particles off degraded cathodes. Afterward, the particles are pressurized in a lithium salt bath and then dried, quickly heated to 800°C and cooled slowly.

Remarkably, the new cathodes made from these regenerated particles had the same energy storage capacity, charging time and lifetime as the originals. The recycling process is efficient as well. Restoring one kilogram of particles only uses 6 megajoules of energy—the equivalent of three-quarters of a cup of gasoline—and half the energy required by other recycling processes currently being developed. That’s because Chen’s process preserves something valuable that other methods destroy—the cathode microstructure. “These cathodes have specific, well-designed microscopic structures that determine battery performance. A lot of engineering and energy are already spent making these structures. We don’t want all that to go to waste,” says Chen.

Moving forward, researchers are optimizing this process so that it can be economical on an industrial scale. And on the flipside, Chen’s team is now working on a process to recycle the anode, or the battery’s negative electrode. “We’re doing our part now to ensure that one day, lithium-ion batteries will be just as easy and economical to recycle as lead-acid batteries,” says Chen. “The sooner we solve this problem, the less it will become a problem for future generations.”