Science

The race to close the EV battery recycling loop

IN LATE OCTOBER 2019, a fire broke out at a recycling facility in Scottsdale, Arizona. The blaze consumed a 40,000-square-foot site, and 60-mile-per-hour winds blew a massive smoke plume across a nearby highway, forcing local officials to close the road. It took firefighters until the next day to extinguish the flames. In the aftermath, the company that operated the site had to suspend collection in nearby cities; the scorched compound had been equipped to handle 85,000 tons of waste a year, and now that junk had nowhere to go except a landfill.

The culprit? A lithium-ion battery like the ones found in phones and laptops. While these hyperefficient cells are generally safe, they continue to store volatile energy even after they die, which means that careless disposal can cause explosions and fires. A 2021 report from the Environmental Protection Agency found public records of such conflagrations in 28 states between 2013 and 2020, and flagged one facility that had had more than a dozen in a single year. The risk will only grow: The global lithium market can be expected to multiply by a factor of 20 by 2030, according to an estimate from research firm Rystad Energy.

The fact that so many batteries end up in scrap heaps poses an even more profound problem for the transition away from fossil fuels. Their contents are a key component of electric vehicles, but the metals they contain—lithium, cobalt, and nickel—are getting ever harder to obtain and often come from only a few countries. Powering the next generation of EVs will entail mining thousands of tons of lithium and cobalt from salt flats and ore deposits around the world, a process that is as ecologically destructive as it is expensive.

“We should try to recycle anything we can, but in the case of batteries, it’s become even more important,” says Fengqi You, an engineering professor at Cornell University who studies the life cycles of elements like lithium within energy systems. You points out that our domestic EV industry depends on lithium that is mined and refined in countries around the world, giving us little domestic control over the production of essential materials. If anything happens to the global supply chain, our access to these precious metals is disrupted, delaying efforts to turn to green technologies.

This machine leaches impurities out of shredded batteries, leaving behind lithium, nickel, cobalt, and graphite. Ryan Roddick

The good news, though, is that the dead can rise again. The key metals contained in old batteries like the one that started the fire in Scottsdale are ripe to be plucked out and pumped back into the supply chain. With the right infrastructure, we could drastically reduce the amount of mining needed to supply metal for new cells—all while cutting down the risk of literal dumpster fires.

As EVs take off in the US, a handful of startups are working to do just that. One of the most advanced, Ascend Elements, is opening a massive battery recycling facility in Georgia this summer where it will recover lithium, cobalt, and nickel, and its competitors aren’t far behind. Together these companies are racing to scale up before the first full generation of EVs gets scrapped. Their efforts have the potential to close the loop, creating a system that is less dependent on fossil fuels—and on unnecessary mining.

BRITISH-AMERICAN chemist M. Stanley Whittingham outlined the first conceptual framework for a rechargeable lithium-ion battery in the late 1970s, winning a Nobel for his efforts in 2019. Entities from NASA to Oxford University further developed his core technology over the next decade. But the concept didn’t go commercial until 1991, when Sony started using the cells to bump up the life of its camcorders. The energy density such batteries can hold has almost tripled since then, and the price of producing them has fallen by more than 97 percent within that same period, from around $7,500 in 1991 to less than $200 in 2018.

All batteries work by storing chemical energy and converting it to electricity. An ordinary cell contains different conductive metals in two terminals: the anode, or negative side, and the cathode, or positive side. These two components are separated by a chemical medium known as an electrolyte. When you turn on a device, the pent-up electrons in the anode stream out of the cell, through a circuit, and toward the cathode, attracted to its positive charge. The electrons’ movement through the circuit is what generates juice.

In an ordinary battery, there’s no way to reverse this process. When enough pent-up electrons have left the anode, the whole thing dies. Lithium-ion batteries, on the other hand, have a much longer life thanks to their titular element, which is one of the lightest and most reactive metals on the periodic table. In an uncharged state, a bunch of lithium atoms hang out in the cathode. When you plug your device into a power source, those reactive lithium atoms are quick to surrender their electrons, which move through the external circuit before coming to rest in the anode. The key advantage is that those departing electrons leave behind positively-charged lithium ions, which are then drawn by the negative charge of the power source through the electrolyte toward the anode, where they become trapped. When you disconnect your device from the power source and turn it on, the process reverses. The naturally unstable lithium ions move back through the electrolyte to return to the cathode, while the electrons move to join them, generating electricity along the way. The electrons and the ions now hang out in the cathode until the next time the battery charges.

Machine extracts minerals from old batteries
Ascend Elements’ machinery recovers graphite from shredded lithium-ion batteries for sale to traditional recyclers. Ryan Roddick

The structure of this metal cathode is key to the battery’s longevity: It functions as an atomic lasagna of metals like nickel and cobalt, with layers thin enough that lithium ions and electrons get trapped between them. As the ions move back and forth across the battery, though, they distort this lasagna, causing the atomic architecture to swell and crack. Every charge cycle causes a number of other uncontrolled chemical reactions that degrade the battery over time, much as our own body degrades in the normal course of aging. You usually can’t see this decay with the naked eye, but over the course of a couple of years, the power cell has a harder time moving energy. The average lithium-ion battery is good for a few thousand charge cycles before it starts to wither away. (Even then, though, the battery retains charge, which is what makes them so flammable as they molder.)

The rapid growth of the EV industry has created a surge in demand for the metals that make this all possible—including the titular lithium. The result has been a mining boom in some of the countries with significant deposits, like China, Chile, and Australia. Worldwide production tripled from 31,000 tons a year in 2010 to 110,000 in 2021. But with the global EV market growing around 20 percent each year, demand is rising much too fast for any producer to keep up. The International Energy Agency predicts annual lithium production could fall short of demand by nearly 2 million tons by 2030. And while at least three or four continents have the potential to mine the metal, almost all the refineries and battery factories are in China, resulting in a classic bottleneck. If capacity does not increase, research firm Rystad Energy has said, the price of the material could triple by the end of the decade.

Soaring demand creates higher environmental costs too. Companies use tens of billions of gallons of water per year to pump the metal out of the ground, straining resources in already parched countries like Chile. There have been several reports of fish kills and freshwater depletion or contamination near lithium mines in Tibet, Argentina, and the United States.

All these factors strengthen the case for recycling. For their first few decades on the market, lithium-ion batteries weren’t valuable enough for anyone to bother turning spent ones into new material, but a few organizations still tried to keep them out of landfills—most notably Call2Recycle, Inc. Founded and funded by major battery manufacturers in the 1990s in the hopes of mitigating the environmental risks (and legal liability) posed by their products, the nonprofit has since spun up a collection program that draws refuse from three main sources: repair centers, municipal waste facilities, and a network of 16,000 public-facing drop boxes across the United States. Last year it collected more than 8 million pounds of discarded cells.

Scientist checks liquid for metals
Dhiren Mistry, a battery materials engineer at Ascend Elements, tests an aqueous solution containing recovered metals. Ryan Roddick

“When we first started, the predominant battery chemistry was nickel cadmium,” says Eric Frederickson, the program’s managing director of operations, referring to a type of cell often used in bulky, yet portable power tools. Now, he says, “lithium ion is the single largest chemistry of batteries that we collect.”

For a number of years, the US capacity for recycling lithium was so low that Call2Recycle had to ship its spoils abroad. Now, though, there’s a new customer on the scene, one that promises to turn these discards into ingredients for brand-new EV power cells.

ASCEND ELEMENTS’ research and development facility sits in a nondescript office park just outside Worcester, Massachusetts. If you stood outside, you’d likely guess that everyone within spends their days tapping away on computers. The reality is a bit messier: The front office leads back into a warehouse where the company has been fine-tuning its lithium-ion battery recycling process and preparing to scale it up.

Ascend’s system is based on the company’s own spin on a process called hydrometallurgy, which involves dissolving crushed-up metals in a chemical solution and leaching them back into solids again. It’s an improvement on an older and less elegant technique known as pyrometallurgy, which requires smelting batteries and separating out the superheated components—creating toxic gases like dioxins and furans.

After handing me a pair of safety goggles, Ascend’s co-founder and chief technology officer, Eric Gratz, shows me the works. Shouting over the constant whine of a generator, he ushers me into a high-ceilinged space dominated by a dozen interconnected tanks and machines. There are three steel vats towering over us, a pair of 10-foot-long contraptions that look like accordions, and a set of several smaller tanks connected by pipes and tubes.

All together, Gratz says, the machinery functions like a giant French press coffee maker. Ascend buys dead batteries from collectors like Call2Recycle or from EV manufacturers, then grinds them up in a fine-toothed shredder. The residue arrives at the Worcester facility as a dark powder—“black mass,” in industry parlance—that takes the place of java beans in this chemical brew. The goal is to liquefy the dead metal, remove impurities like plastic and unwanted metals, alter its chemical structure, then condense it back into powder so it can be used for new manufacturing.

First Gratz leads me to the trio of vats, behind which sits a hopper holding the shredded batteries. Step one is to pipe the black mass into the vats, where it dissolves in a proprietary chemical mixture, loosening the atomic structure of the lithium, nickel, and cobalt inside. That part isn’t all that difficult. The trick is turning it back into powder again.

Ascend wants to produce material for new cathodes—the positive side of the battery—since that’s the hardest to come by. But because pulverized batteries contain several different metals, some of which aren’t useful, Ascend first has to separate out any it doesn’t need. Tiptoeing around lab techs as they bustle back and forth, we reach the accordion-like machines. These pump the black-mass slurry through a set of filter panels to strain out irrelevant solids—the equivalent of pushing down the grounds in a French press. Fragments of graphite and copper stick to the filters, leaving black and greenish-yellow stains; Ascend later packages and sells these to traditional recyclers.

The next step is to separate the remaining mixture into two key components: the lithium and a melange of nickel, cobalt, and manganese. The exact method by which Ascend does this is proprietary—part of what separates the company from its competitors—but Gratz allows that it takes advantage of lithium’s unique chemistry. While most metals are more likely to dissolve when heated, lithium is less soluble at higher temperatures. This means the team can isolate the all-important metal by heating the mixture. The resulting granules look a lot like the salt you’d keep in an ordinary shaker.

Then they precipitate the black mass back into powder, another proprietary process, this one taking place in a set of machines that look like older-generation droids from Star Wars—big, boxy trapezoids with little doodads on top. The team at Ascend can adjust the concentrations of nickel and cobalt in each batch to the specifications of buyers: A battery with more nickel, for example, has a shorter shelf life but can hold more energy, making it ideal for vehicles that need to travel hundreds of miles. Once a mixer recombines the powder with the extracted lithium, the final product looks just like the one that came in, as evidenced by the before-and-after jars Gratz hands me. But the molecular structure of the recycled powder is rejuvenated, ready to again store hyperreactive lithium ions.

The process is remarkably efficient: Ascend recovers 98 percent of the most expensive metals, nickel and cobalt. For lithium, Gratz says, that figure is more like 80 percent. The black powder that leaves the factory is quite literally ready to roll. Battery manufacturers usually spray the substance on foil and roll or fold the material into fresh battery cells.

COMPLICATED AS Ascend’s operation in Worcester may seem, it’s just a prototype for a 154,000-square-foot battery recycling plant set to open near Atlanta in the summer of 2022. The operation will sit at the nexus of an EV boom in the Southeastern US. Volkswagen will soon start up an electric vehicle division at its plant in Chattanooga, Tennessee, and Ford is building an assembly plant and multiple battery factories, including in Kentucky and Tennessee. Ascend’s facility won’t start up for another few months, but manufacturers like SK Battery America, which helps power heavy hitters like Ford and Volkswagen, have already begun to ship over pallets of manufacturing scrap. It’s piling up by the ton, just waiting to hit the road.

When it’s up and running, Ascend’s Georgia plant will be able to turn around 33,000 tons of dead batteries and other waste per year, resulting in enough recycled metal to spark up to 70,000 EVs. Auto manufacturers will be able to sign a simple one-way contract to buy the reconstituted material from dead EV cells, vice president of marketing Roger Lin explains, or they could do a two-way deal to provide excess scraps from their factories and get them back in revived form. Ascend could also take the dead batteries from auto manufacturers and then create new material for anyone who wants it.

Ascend CEO Mike O’Kronley is confident the old EV batteries his plant will depend on won’t end up like so many forgotten cell phones stashed in drawers. “One EV battery is equivalent to a thousand from cell phones,” he says. “It’s much easier to collect and transport to a recycling center.” Auto shredders and junkyards, he contends, have an incentive to sell them to companies like Ascend.

Though Ascend may have the head start in lining up customers, it does face strong competition: Li-Cycle, a Canadian recycler building a plant near Rochester, New York, and Redwood Materials, a company founded by Tesla’s former CTO. Both firms are scaling up their own systems, using hydrometallurgical processes similar to Ascend’s.

Right now, not enough EVs have been retired to supply the quantity of batteries needed to meet the demand for reclaimed metals. “If we recycled every battery in the world, the most recycling can provide is maybe 20 to 30 percent of the demand,” says Ascend CTO Gratz. As long as the total number of EVs on the road continues to increase, we’ll need to keep mining significant amounts of lithium, cobalt, and nickel.

However, Ascend is banking on the majority of the population eventually driving EVs and turning in their old ones for new models. “Then,” Gratz says, “we can just keep recycling the same nickel and cobalt and lithium atoms over and over again.”

This story originally ran in the Summer 2022 Metal issue of PopSci, as the third in a three-part series about batteries. Read part one and part two or more PopSci+ stories.



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