Lithium-ion battery recycling goes large

The electric vehicle (EV) revolution is shifting into high gear. Automakers sold over 10 million EVs last year, more than half of them in China, and global sales should top 14 million this year, according to the International Energy Agency (IEA). That growth is being accompanied by a surge in lithium-ion battery manufacturing. The IEA says that in 2022, EV battery demand soared to 550 GW h, a roughly 65% rise from the previous year.

Yet after a decade or 2 of service, the performance of these batteries will decline until they can no longer provide sufficient range for their EVs. Some batteries may be repurposed for stationary energy storage, but sooner or later they will be retired for good. These end-of-life (EOL) batteries might have once been given an unceremonious burial in a landfill, but today they are far more likely to be recycled.

Recycling isn’t just a more sustainable option. It offers a vital way to recover precious resources within the EOL batteries, particularly cobalt, nickel, and lithium, which are destined to live again in new batteries. In principle, recycling can be a cheaper way to access these metals than mining and refining.

So companies around the world are scrambling to build battery recycling facilities, and more than 200 businesses now have a combined capacity to recycle more than 1 million metric tons (t) of EOL batteries per year, according to Circular Energy Storage, a London-based consultancy. “There’s a huge amount of capacity coming in now,” says Hans Eric Melin, the company’s founder and managing director.

But the burgeoning recycling industry faces challenges on several fronts. Many recycling plants use energy-intensive processes and produce copious carbon dioxide emissions, or they require oceans of strong acids and oxidizers, tarnishing the environmental credentials of EVs. And although these processes can extract the most valuable metals from EOL batteries, other components—including graphite, plastics, solvents, and electrolyte salts—are rarely recovered. Instead, they are often burned to generate heat or power, thus destroying most of their economic value.

Yet another challenge is that the chemistry of EV batteries is constantly evolving. Recycling processes will have to adapt to these changes in the coming years—not only to recover materials efficiently but also to ensure that the recycling business remains profitable.

Meanwhile, new regulations in China and Europe are helping stimulate recycling. But there are still many uncertainties about how these regulations will affect the battery business. In Europe, for example, some industry watchers fear that exports of EOL battery materials to recyclers in Asia could make it difficult for European manufacturers to source the recycled materials needed to build new batteries. “I think that’s a huge concern, both to the industry and to regulatory bodies,” says Sarah Colbourn, a senior analyst at Benchmark Mineral Intelligence in London.

Battery breakdown

When recyclers talk about battery chemistries, they are generally most interested in the batteries’ cathodes. And those cathodes vary by region and product being powered.

In Europe, nickel manganese cobalt oxide (NMC) has become the preferred cathode recipe. Over the past decade, this blend has trended toward higher nickel content, which offers higher energy density. In earlier versions, the components were present in equal proportions. The latest generation uses 80% nickel.

In China, the dominant cathode chemistry is lithium iron phosphate (LFP)—which is cheaper than NMC but provides a lower energy density. Consequently, cars with LFP batteries tend to have a shorter range than those with the same mass of NMC batteries. But as China exports ever more EVs to Europe and the US, and other battery makers adopt LFP technology, Benchmark predicts that LFP and NMC will each make up about 40% of the global battery market by 2030.

Recyclers also have to contend with a range of other battery chemistries—older formulations and those used in portable electronic devices, which include lithium cobalt oxide, lithium manganese oxide, and nickel cobalt aluminum oxide.

Because EVs are still fairly new to the market, relatively few EOL batteries are available to recyclers compared with the number still on the road. For now, roughly half of recycling plants’ feedstock material is made up of production scrap from battery factories, including electrode offcuts and faulty cells. But over the next decade, EOL batteries will come to dominate that feedstock as battery production becomes more efficient and the availability of EOL batteries grows.

While recyclers wait for those EOL batteries to arrive, a lot of their current capacity is underused. “On a global basis, we have much more capacity than what we need,” Melin says.

But by 2030, roughly 1.2 million EOL EV batteries will need to be recycled per year, and that number could rise to 14 million per year by 2040, according to the International Council on Clean Transportation (ICCT), a nonprofit organization. “In preparation for these batteries returning in high volumes by the early 2030s, it does make sense to get the capacity in place,” Colbourn says.

Recycling starts by discharging EOL batteries and disassembling them into their constituent cells. After that, there are essentially two strategies operating at an industrial scale today.

Some processes shred the cells; sift out the plastic, copper, and aluminum that were in the cell body and current-collector foils; and use heat to drive off the organic solvents that carry electrolyte salts such as LiPF₆. These steps leave a sooty pile of granulated battery guts called black mass, containing cathode metals and the remains of the graphite anode. The black mass goes through hydrometallurgical processing, which uses strong acids and oxidizing agents to extract and separate metal salts. The salts are typically sulfates or hydroxides of nickel, manganese, and cobalt, along with lithium hydroxide or lithium carbonate.

The alternative approach involves pyrometallurgy. In this process, cells are smelted in a furnace at up to 1,500 °C to burn off all the carbon-based components. The high temperature produces a mixed-metal alloy that includes cobalt, copper, and nickel, along with a slag containing manganese, aluminum, and lithium. Metals can then be recovered using hydrometallurgy. Pyrometallurgy tends to be cheaper than shredding and can tackle pretty much any kind of battery design or chemistry. But the heat also drives off lithium and reduces its recovery rate.

Recycling makes most of its money by recovering nickel and cobalt. Although both hydrometallurgy and pyrometallurgy can also recycle LFP batteries, the absence of those lucrative metals means recyclers have to operate at larger scales and with smaller margins. “Outside of China, [LFP recycling] is not really making financial sense right now,” Colbourn says.

Europe plays catch-up

China has most of the EOL battery recycling capacity today. Contemporary Amperex Technology Co. Limited (CATL), the world’s biggest battery maker, is also China’s biggest battery recycler. Operating through a subsidiary called Brunp, it has a domestic and international network of pyrometallurgical facilities with a total recycling capacity of 120,000 t per year. This June, CATL announced that it hopes to establish several more battery recycling facilities in the European Union and in North America.

Dozens of other Chinese companies are rapidly building their own recycling capacity. For example, China’s largest producer of lithium salts, Ganfeng Lithium Group, already has recycling capacity of 34,000 t and started commissioning a 100,000 t facility in July. Metal refiner GEM announced in July that it would build a 100,000 t plant in Sichuan Province to process NMC batteries and production scrap and a 50,000 t plant dedicated to LFP batteries.

Meanwhile, European companies are hurrying to catch up. One of the biggest, the Belgian materials technology company Umicore, has operated a 7,000 t battery recycling plant since 2011 and announced in March that it hopes to build an enormous 150,000 t facility in Europe that will open in 2026.

Umicore’s process relies on pyrometallurgy and hydrometallurgy to recover more than 95% of the nickel, copper, and cobalt from EOL batteries. The firm also claims to capture over 70% of the lithium—unusually high for a pyrometallurgical process—by extracting the metal from flue dust and ash as well as from slag.

In a statement, Umicore says pyrometallurgy is “the most cost-effective and scalable method for quickly reducing high volumes of battery materials—a factor that will be crucial as battery recycling volumes grow and the mixture becomes more complex.”

Yet others see pyrometallurgy as yesterday’s technology. “The problem with pyro is that it destroys so much value,” says Gavin Harper, a University of Birmingham researcher who studies EV policy issues. “It’s a bit of a sledgehammer to crack a nut.”

That’s why so many recyclers favor shredding and hydrometallurgy. In April, for example, Fortum Battery Recycling started operations at a hydrometallurgical plant in Harjavalta, Finland, that claims to recover more than 95% of the cobalt, manganese, nickel, and lithium present in black mass. Fortum says it is also developing systems to recover graphite, solvents, and other components. The company aims to have 200,000 t of recycling capacity across Europe by 2030.

Lots of other European companies, including the chemical giant BASF and the multinational mining company Eramet, have recycling plants in the works. But one of the most high-profile efforts comes from Northvolt, the Swedish battery maker that launched in 2016 with the promise to produce the world’s greenest lithium-ion battery.

Its first factory, Northvolt Ett, is based in Skellefteå in northern Sweden and started producing batteries at the end of 2021. Its current annual production capacity of about 16 GW h of batteries will increase in the next few years to 60 GW h, enough for about 1 million electric cars per year. Its customers include BMW, Volkswagen, and Volvo Cars.

The company’s green ambitions are focused on having a very low carbon footprint. Building a typical Li-ion battery causes about 100 kg of CO₂ emissions per kilowatt-hour. But Northvolt says it has whittled this down to 33 kg of CO₂/kW h, largely because of its use of renewable electricity at the Skellefteå facility.

Northvolt also aims to derive half its raw materials from recycled batteries by 2030, which will help reduce the carbon footprint of new batteries even more. In 2022, the company opened a recycling facility called Hydrovolt in Fredrikstad, Norway. Norway was one of the first countries to see a major EV rollout and consequently has a sizable quantity of EOL batteries. The preprocessing facility is expected to discharge, dismantle, and crush 12,000 t of battery packs per year—essentially dealing with all of Norway’s EOL EV batteries—to recover plastics, copper, aluminum, steel, and electrolyte and then ship the remaining black mass to Skellefteå.

There, a new recycling facility called Revolt Ett is gearing up to recover battery-grade sulfates of nickel, manganese, and cobalt along with lithium hydroxide using a hydrometallurgical process.

When Revolt Ett opens early next year, about 75% of its feedstock will be battery manufacturing waste from Skellefteå, and it will have an initial capacity of 8,500 t. It will eventually expand to 125,000 t, funneled from a network of preprocessing facilities similar to Hydrovolt that will be located around Europe. A second Revolt facility is already being planned at a recently announced Northvolt battery production site near Montreal.

Revolt can handle most battery chemistries, but Northvolt will mainly use it for batteries rich in nickel and cobalt. The company reckons it can recover 95% of the nickel, manganese, and cobalt, and 75% of the lithium from black mass. Although carbon-based materials recovered from the batteries will be burned for energy recovery, Emma Nehrenheim, chief environmental officer at Northvolt, says the Revolt process is under continual development and should be able to recycle these materials in the coming years. “Every day, the methods that we use get more sophisticated in the lab,” she says.

Ultimately, Northvolt aims to reduce the carbon footprint of its batteries to 10 kg of CO₂/kW h by 2030. Improving and expanding its recycling process will play an important part in that effort, but so too will switching upstream operations, such as mining and refining, to clean energy. “The key is to bring as much of the supply chain as possible onto a renewable grid,” Nehrenheim says.

Remade in the US

Battery recyclers in North America are also trying to scale up. The ICCT estimates that lithium-ion battery recycling facilities in the US can currently process about 100,000 t of material per year, and companies have announced plans for facilities capable of processing more than 650,000 t per year by the end of the decade.

The existing facilities in North America are primarily preprocessing plants that produce only black mass, but several firms are on the verge of opening more advanced facilities that will make battery precursors or even cathode materials. Like their counterparts in Europe, these firms are competing to show they have the greenest process.

In an unpopulated patch of desert outside Reno, Nevada, several battery recyclers are setting up shop in a growing industrial park where gleaming electric semitrailers from Tesla’s nearby battery production facility share the road with wild horses.

At the southern end of the sagebrush-covered complex, Redwood Materials is building a facility that converts old batteries and manufacturing scrap to cathode materials using both heat and hydrometallurgical techniques.

Redwood’s recycling process begins by heating spent batteries using the leftover energy stored inside them. This process discharges the batteries and decomposes plastic, volatile organic compounds, and battery electrolyte, which allows Redwood to avoid labor-intensive dismantling steps required at other hydrometallurgical plants.

The discharged batteries are then shredded and move on to a hydrometallurgical process in which metals like lithium, nickel, cobalt, and copper are recovered. Scrap material from battery factories, which made up half of Redwood’s input in 2022, doesn’t need to be heated since it isn’t charged. It’s shredded and goes straight to the hydrometallurgical steps.

The company’s existing hydrometallurgical facility near Reno can process 2,500 t of material per year, according to a US Department of Energy environmental assessment. Redwood hopes to expand that capacity to 10,000 t by the middle of next year. By 2026, the company aims to use the recycled material, along with mined metals, to produce 20,000 t of cathode powder.

In a recent study, which hasn’t undergone peer review, a team led by researchers from Stanford University used data provided by Redwood to calculate that the company’s process releases about 6.5 kg of CO₂ to make enough material for 1 kg of cathode material from used batteries, which is lower than another hydrometallurgical process considered in the study (ChemRxiv 2023, DOI: 10.26434/chemrxiv-2023-qwmb2-v4). Since the initial heating step requires minimal external energy, Redwood says, its process also produces fewer emissions than pyrometallurgy.

A few kilometers down the road from Redwood, Aqua Metals claims that it can recover battery metals with an even cleaner process. At the company’s pilot plant, a row of transparent tanks bubbles with a wine-colored liquid loaded with cobalt and a nickel-rich solution the color of a Caribbean lagoon. The fluorine from a 1 t bag of black mass produces a strong smell, which Chief Engineering and Operating Officer Ben Taecker likens to the smell of bourbon.

Aqua Metals mixes black mass with low-grade sulfuric acid and uses electric current to help reduce the metals and get them into solution. A filter press squeezes carbon and chunks of plastic out of the resulting slurry, and a second filter removes iron and aluminum, which are precipitated via a pH adjustment. The company then uses organic solvents to separate nickel and cobalt, leaving a liquid containing lithium hydroxide. In the final steps, lithium hydroxide is crystallized, and nickel and cobalt are plated electrochemically into thin sheets of metal.

Taecker says conventional hydrometallurgical processes consume large amounts of sodium hydroxide, peroxides, and other chemicals, all of which generate a big carbon footprint. He says Aqua Metals aims to reduce the need for chemicals by using renewable electricity to assist in the separation of metals and regenerate the chemicals it does use. “We’re really taking chemicals and replacing them with electricity,” Taecker says.

Aqua Metals, which got its start in the lead-acid battery recycling business, has already started converting an old walnut processing facility in the same industrial park to a demonstration-scale plant that will be able to process 3,000 t of black mass per year, 30 times as much as the existing pilot. The company hopes to eventually increase the facility’s capacity to 10,000 t.

Nevada isn’t the only state attracting battery recyclers. Firms are also building facilities in the southeastern US, close to anticipated battery plants that will have scrap to recycle. Redwood is planning another large recycling plant in South Carolina. And in 2022, Li-Cycle opened a preprocessing facility in Alabama that converts spent batteries into black mass. That is its fourth facility in North America.

Rather than dismantling and discharging batteries, Li-Cycle shreds entire batteries that are submerged in a liquid, which prevents fires. CEO Ajay Kochhar says avoiding manual processing steps makes it easier to process large volumes of batteries. “We figured out how to do that safely but also get good recoveries,” he says.

In Kentucky, Ascend Elements plans to open a facility later this year that will convert black mass to battery precursors and cathode material, eventually producing enough for 250,000 electric vehicles per year.

Roger Lin, Ascend’s vice president of global marketing and government relations, says the efficiency of the firm’s process sets it apart from other companies. Rather than extracting lithium, cobalt, and nickel chemicals from black mass and then recombining them, the company removes everything else. That leaves a mixture of metals that can be directly converted to cathode materials.

“Our process removes what you don’t want and does it all in a single step,” Lin says. “It’s sort of an upside-down approach to hydrometallurgy.”

The US government and venture capital firms are placing big bets on the success of these companies. The US Department of Energy (DOE) has conditionally agreed to give Redwood a $2 billion loan, while Li-Cycle is in line to receive a $375 million loan. In 2022, the DOE awarded Ascend $480 million in grants to build its Kentucky facility, and the firm followed that with over $400 million in funding from private investors. In August, Redwood raised more than $1 billion from investors.

All these firms face significant challenges as they scale up pilot or demonstration processes to larger facilities. Li-Cycle was on track to open a commercial-scale hydrometallurgical recycling plant in Rochester, New York, by the beginning of 2024. But in October, the firm announced that it was pausing construction because costs were higher than expected. In a recent conference call, Li-Cycle executives told investors that the firm still hopes to develop the project but will likely require additional financing before resuming construction.

Li-Cycle has a demonstration-scale hydrometallurgical plant in Kingston, Ontario, that processes about 1 t of black mass per day. The Rochester facility was expected to be 100 times as large.

In an interview before the Rochester project was paused, Kochhar said many companies getting into battery recycling underestimate how complex it is. “Some of this stuff looks elegant and simple, but treating batteries is pretty hard,” he said. “These things take time.”

Black mass mess

The focus of firms such as Northvolt, Redwood, and Aqua Metals on batteries’ carbon footprint isn’t just a matter of environmental altruism. They are keenly aware of the growing web of legislation that is reshaping the battery manufacturing and recycling industries.

Over the past 5 years, for example, China has deployed regulations to ensure that domestic EV manufacturers take responsibility for recycling the EOL batteries in their vehicles. The country has also set nonbinding targets to recover 98% of the batteries’ nickel, cobalt, and manganese and 85% of the lithium.

The European Union has gone further, establishing a new Batteries Regulation that will apply starting in February. The regulation will phase in mandatory targets for recycling and reuse of battery materials and will introduce a system of battery passports to keep track of EOL batteries and ensure compliance.

Starting in 2026, 65% of the mass of EOL Li-ion batteries must be recycled. That number will rise to 70% in 2031. By 2028, the industry must recover 90% of the cobalt, copper, and nickel from EOL batteries, along with 50% of the lithium. In 2032, those requirements will increase to 95 and 80%, respectively. “It’s a huge endorsement for recycling. In terms of mandated recycling, it’s unmatched by other regions,” Colbourn says.

The regulations also set stringent targets for the amount of recycled material to be included in new batteries. In 2031, 16% of the cobalt content should come from recycled material, and 6% of the nickel and lithium should be recycled material, targets that will rise substantially after 2036. “That’s something that is completely new on the global level. It really helps to ensure that you have a closed cycle,” says Georg Bieker, a senior researcher in the Berlin office of the ICCT.

To make EV battery production more sustainable, European manufacturers and importers will have to declare the carbon footprints of their batteries beginning next year. A maximum permissible carbon footprint, yet to be determined, will apply starting in 2027. Over the next few years, secondary legislation will provide more detail about the specific targets and how those carbon footprints are calculated. That could help clarify competing claims about rival recycling processes’ environmental impacts, which are currently opaque and difficult to compare.

For example, researchers generally agree that pyrometallurgy is less sustainable than hydrometallurgy. But Umicore insists that although pyrometallurgy is energy intensive, its process has a lower carbon footprint than methods relying on mechanical shredding and hydrometallurgical separation. Umicore says this is partly because its method uses fewer chemical processing steps and because combustion of the carbon-based materials in the batteries provides the energy for the smelting step.

Meanwhile, researchers and businesses have questions about whether the EU regulation may have unintended consequences (Science 2021, DOI: 10.1126/science.abh1416). “The requirement for recycled content in the batteries are ambitious and require a true circular economy, with recyclable feedstock remaining in Europe,” Northvolt’s Nehrenheim says. Yet a lot of European EOL battery material ultimately ends up in China.

In principle, China restricts the import of black mass because it’s deemed a hazardous material. But black mass is commonly exported to other Asian countries, where hydrometallurgical plants transform it into mixed hydroxide precipitate—largely nickel and cobalt hydroxides—which is then sent to China.

“We see a huge leakage of material out of Europe,” Nehrenheim says. Given the EU’s imminent requirements on using recycled materials in new EV batteries, that loss could make it difficult for battery makers to meet their quotas.

More legislation could tackle the issue. The European Commission has proposed a Critical Raw Materials Act that would block the export of black mass. It could become law next year. “The regulation is starting to grind things in the right direction, but I think there’s still lots of unanswered questions,” Harper of the University of Birmingham says.

Future proof

The growing focus on the efficiency and sustainability of recycling processes could be a boon for start-up companies developing the next generation of recycling technologies. In Germany, for example, Duesenfeld has a recycling process that recovers not only lithium and other metals from EOL batteries but also graphite, solvents, and electrode foils.

Conventional shredding processes use high temperatures to drive off the solvent within batteries, but these can also trigger reactions with fluorine-containing electrolyte salts that generate toxic and corrosive hydrogen fluoride gas. Companies often deal with this problem by using gas scrubbers, but Duesenfeld’s chief technology officer, Till Bußmann, says some plants have struggled to make the scrubbers work smoothly. “We see a lot of these new recycling facilities not really getting to a fully operational status,” he says.

Instead, Duesenfeld uses a vacuum-drying process to remove solvent at low temperature, avoiding the evolution of hydrogen fluoride. After separating black mass from the electrode foils, its hydrometallurgical process extracts metal sulfates, lithium carbonate, and graphite. Overall, the process recovers 91% of the mass of all materials in the battery, the firm says.

Duesenfeld has been running a 3,000 t per year demonstration plant for the past 2 years and sells 15,000 t plants to recycling companies as turnkey operations. The first of them should be operating next year.

Using a low-temperature process reduces Duesenfeld’s carbon footprint and operating costs, Bußmann says, and recovering a wider range of battery materials makes the process more sustainable and profitable. He hopes that the EU Batteries Regulation will give Duesenfeld’s technology an edge, but he would like the legislation to include requirements for new batteries to use recycled solvents and graphite.

“The regulation is a good thing,” he says, “but in my opinion, the first goals for the next few years are not strict enough.”

Meanwhile, the company Kyburz Switzerland has developed a technology that could help make recycling even more efficient. Rather than shredding the cells, producing black mass, and then laboriously extracting metals as separate salts, it uses an approach known as direct recycling. This involves carefully stripping the materials from intact electrodes so that they retain the precise composition needed for a new battery. This could be particularly useful for LFP batteries, Harper says.

“If you can recover the LFP cathode material as a whole, you retain all of its value,” he says. With fewer chemical processing steps involved, direct recycling could also have a smaller environmental footprint, he adds.

Kyburz makes light-duty electric vehicles, such as three-wheeled delivery scooters, using LFP batteries. These batteries are generally given a second life in other vehicles and a third tour of duty in stationary energy storage facilities. Once they are finally ready for recycling, the company uses a mechanized process to cut open the battery case, remove the electrode packs, and separate the anode and cathode. The electrodes are then dipped in water to detach graphite and LFP from the metal foils.

Olivier Groux, head of battery recycling at the company, says the process recovers more than 90% of all the materials in the battery and uses far less energy than typical pyrometallurgical and hydrometallurgical processes.

Kyburz currently has one recycling machine that can handle 200 t per year. It’s restricted to cuboid LFP cells with electrodes that are wound or folded. But it plans to make more of the machines, and the company has customers lined up to take the first commercial systems in 2025. Groux says it is also working on a more advanced system that can tackle a variety of other cell designs and chemistries.

Harper says direct recycling could become much more common if EV batteries are designed for easier disassembly. But Bieker reckons it will be difficult to develop a direct recycling process that is versatile enough to tackle a broad range of battery types. “I have my doubts that this is something that can be applied on a large industrial scale for EOL batteries,” he says.

Meanwhile, business models are changing quickly. For example, partnerships are being formed between EV manufacturers, recyclers, and battery makers that would keep battery materials within a closed-loop system. This ensures that materials recovered from EOL batteries never reach the open market and instead end up back inside new EVs made by the same manufacturer.

Febrile geopolitics is also shaping the market. In September, the European Commission launched an investigation that could lead to higher tariffs on imported Chinese EVs. China itself imposed stricter export controls on battery-grade graphite in October.

This kind of protectionism might actually benefit the battery recycling industry in the coming years. The reason? Recycling offers greater independence from global supply chains and gives governments a way to secure supplies of critical minerals, all while providing opportunities for domestic economic growth. “It’s in the environmental, economic, and geopolitical interest of governments to have better recycling, so I’m pretty optimistic,” Bieker says.

With additional reporting by Matt Blois

Mark Peplow is a freelance science journalist based in Penrith, England.