Those mines are the dirty underbelly of the renewable energy transition. But once a hunk of metal is pried from the earth, it can be reused basically forever.
Enthusiasts dream of a world in which new batteries are made almost entirely from the scraps of their discarded predecessors.
China is furthest along in trying to realise that vision.
It has more than 50 recycling plants the size of the facility in Nevada, and recyclers provide a tenth of the Chinese battery industry’s lithium and nearly a fifth of its nickel and cobalt, according to Benchmark Mineral Intelligence, a firm that analyses battery supply chains.
Robin Zeng Yuqun, the founder of China’s biggest battery maker, predicts that the country would have “no need” for new battery materials by 2042 because of recycling.
Globally, recyclers could supply about a third of the lithium, nickel, and cobalt needed for batteries by 2040, according to Benchmark Mineral Intelligence.
In the US, the battery recycling industry remains nascent. Many of Redwood Materials’ rivals are struggling – especially after Republicans repealed Biden-era support for EVs and battery manufacturing.
And the recycling process still requires shipping materials back to Asia for incorporation in new batteries.
The ultimate goal for American recyclers is to keep the whole process within the US.
That would allow the companies to make more money selling valuable refined materials to battery manufacturers, and it would give the country a domestic source of battery materials that doesn’t involve mines.
A battery graveyard in the desert
Truckloads of old batteries travel from all over North America to this flat, dusty field in the desert.
It’s a good spot for a battery graveyard, because land in this part of the country provides relatively cheap storage, and arid conditions ensure that the old batteries don’t corrode.
Old batteries from electric vehicles and rechargeable gadgets pile up in the storage lot next to the Redwood Materials recycling plant. Photo / Emily Najera, The Washington Post
Most lithium-ion batteries in the US get recycled, and Redwood Materials executives say their company handles 90% of that.
About 60,000 tonnes of junk rotates through the desert field each year.
Most of it is scrap left over from battery factories, which typically leave about 10% of their raw material on the cutting-room floor.
Redwood also collects old phones and other electronics from e-waste bins scattered across the country.
Company representatives say they’d like much more of their business to come from EV batteries, which each represent about US$2000 of metals and minerals wrapped in one neat package.
Right now, EV batteries account for just under a quarter of Redwood’s business.
“We started Redwood almost too early,” said JB Straubel, who launched it in 2017 after co-founding Tesla, anticipating the wave of spent batteries that would follow the rise of EVs.
“We saw the big opportunity coming in the future, and now we’re sort of in the midst of that pivot.”
Batteries from worn-out power tools and other devices sit in a barrel, waiting to be recycled. Photo / Emily Najera, The Washington Post
The bulk of the EV batteries the company recycles these days are from cars sold about seven years ago, when EVs made up 2% of new car sales.
That share has since grown to about 9%, so, in the future, there should be many more valuable batteries to recycle.
As batteries arrive at the plant, workers sort them into piles based on their size, chemistry and packaging.
They can later pull old batteries from different piles when trying to obtain a specified mix of minerals – for instance, combining a few EV batteries with some old electric toothbrushes and diabetic glucose monitors to get the right recipe.
When the materials are ready for recycling, workers load the batteries they need onto a truck and drive them up a winding road to the plant.
Breaking down batteries
Before the valuable materials in batteries can be extracted, they have to be separated from the cheaper components.
At the Redwood plant, a crane arm that resembles a giant claw machine loads batteries on to a conveyor belt, which drops them, one by one, into a big, slowly rotating oven.
A conveyor belt pulls batteries into a giant toaster oven that will cook off their packaging and electrolytes and leave valuable minerals. Photo / Emily Najera, The Washington Post
Electric heating coils warm the air to several hundred degrees – hot enough to cook off all the plastic, glue and electrolytes in the batteries. After an hour, the remaining lumps of charcoal-like material get crumbled into a powder called “black mass”, which contains a valuable mix of lithium, nickel, cobalt, manganese and more common metals such as copper, aluminium and steel.
Next comes the refining process. Redwood uses magnets, sieves and jets of air to separate steel, copper and aluminium out of the black mass powder. Then they dunk what’s left into a chemical soup of water and sulfuric acid.
Workers change the acidity of the solution to pull out the nickel and cobalt and then evaporate the water to leave behind lithium. The plant captures and recycles the water vapour to minimise water usage.
After two hours, they’ve sorted out about 95% of the nickel, cobalt and lithium in the original battery – but all of it has bonded with sulphur to make nickel sulphate, cobalt sulphate and lithium sulphate, which have to be refined more before they can go into a new battery.
Redwood’s method for breaking down batteries is easier on the Earth than mining new metals, according to an independent analysis from researchers at Stanford University, the City University of Hong Kong, and Kenyon College.
Recycling batteries this way lowers carbon emissions by 58% and water consumption 72% compared with conventional mining.
The process has its downsides.
Redwood doesn’t recycle the cheaper materials in batteries.
Instead, during the heating stage, the plastics, electrolytes and binders get turned into a mix of air pollutants that could cause health problems and environmental damage.
Giant air filters help catch the harmful gases, releasing water vapour and CO2 as a by-product.
Other companies instead dunk the batteries in water and shred them into black mass – which doesn’t produce as much air pollution, but does use more water, a scarce commodity in the desert, and creates contaminated wastewater.
This method can usually recover plastic, but it doesn’t recover electrolytes or the binders that hold batteries together.
To recycle every part of each battery, including all the electrolytes, workers would have to manually disassemble each pack and create a unique recycling process for hundreds of different battery designs and chemistries.
Very few recyclers do this – usually in small quantities for specific products.
“It’s extremely difficult to implement,” said Chiara Ferrara, associate professor of physical chemistry at the University of Milano-Bicocca in Italy.
Building new batteries
Redwood Materials sells the minerals it has sorted – enough to make 300,000 EV batteries a year – to companies in Asia that will refine them further into pure materials that can be made into new batteries.
Redwood Materials has a network of more than 100 drop-off bins across the United States, where people can toss old lithium-ion batteries to be recycled. Photo / Emily Najera, The Washington Post
But Redwood is expanding to take on the next step of the process: turning recovered minerals into “cathode active materials”, the stuff that makes up the positive end of a lithium-ion battery and most of its total cost.
If the company can master this step, it would fill a missing link in American battery recycling.
Rather than exporting minerals abroad, it could sell cathode materials directly to US battery makers, creating a more sustainable, domestic supply of critical minerals.
The company has built a 40m-tall building to host the giant machines that are starting to turn minerals into cathode active materials in small quantities.
“The ambition is to have a similar structure to China,” said Beatrice Browning, who heads research on battery recycling technology at Benchmark Mineral Intelligence.
China has built recycling hubs where nearby factories break batteries into black mass, extract key minerals, refine them into high-quality battery materials and then assemble new batteries.
The Redwood Materials recycling plant sits amid desert hills, not far from a Tesla gigafactory and several data centres. Photo / Emily Najera, The Washington Post
In the meantime, Redwood Materials has debuted a more direct way to reuse old EV batteries: putting them to work powering microgrids.
Most car batteries that come into the plant are too worn down for the heavy-duty work of accelerating a vehicle to highway speeds, but they still have enough life left in them to store energy from solar panels and slowly trickle power out after the sun goes down.
“Secondary use is a no-brainer,” said Zheng Chen, a nanoengineering professor at the University of California at San Diego. “You have a lot of old batteries which are still okay. It’s good to use them before you send them into the recycling process.”
Today, this is the only place in the US where batteries get a second life. In a 1ha patch of desert next to the recycling plant, Redwood has hooked up 792 old car batteries to a solar array to power a miniature AI data centre.
It runs 24/7 without connecting to the power grid.
When one of the old batteries finally gives out, Redwood replaces it with another one – and takes the fully spent cell inside to be torched, crumbled and dissolved into a new generation of batteries.
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