A technician working on a used lithium-ion battery from an electric car. (Shutterstock.com)

Overcoming the Lithium-Ion Battery’s Achilles Heel

By Will Uhl

Since the early ‘90s, the tech world — and shortly after, everyday life — has been increasingly dependent on lithium-ion (Li-ion) batteries. Lighter and longer-lasting than yesteryear’s alkaline batteries, they’ve become the standard for powering portable electronics. And as the price of Li-ion batteries has plummeted, dropping 97 percent over the past three decades, they’ve become ubiquitous.

But as increasing numbers of Li-ion batteries are reaching the end of their lifecycle, a problem has emerged with growing urgency: recycling. Li-ion batteries are complex and potentially dangerous to disassemble — much more than traditional alkaline and lead-acid batteries. On top of that, the hazards of improper lithium ion battery disposal are only now becoming apparent. Because of this, less than five percent of Li-ion batteries are currently recycled. Now, as the market for Li-ion batteries balloons, a Princeton startup is poised to pioneer the next generation of Li-ion battery recycling.

EVs and the Surging Market

In a bid to mitigate the climate crisis, the European Union (EU) proposed a sales ban on all fossil fuel-powered vehicles by 2035. Helen Clarkson, chief executive of the nonprofit organization Climate Group, put the urgency behind the switch simply: “The science tells us we need to halve emissions by 2030, so for road transport it’s simple — get rid of the internal combustion engine.” Instead of combustion engine vehicles, the EU wants to shift to electric vehicles (EVs) — zero-emission vehicles powered by Li-ion batteries.

Dr. Chao Yan

The EU isn’t alone in their vision of an EV future: according to the U.S. Department of Energy, 140 million electric vehicles are predicted to be on the road by 2030. “By 2020, the global annual [EV] sales were roughly 2 million. By 2021, it’s five million. This number is going to reach about 30 million annual sales by 2030,” said Dr. Chao Yan, a post-doctorate engineering researcher at Princeton University and founder of Princeton NuEnergy (PNE) — a technology and manufacturing startup working on modernizing the Li-ion battery recycling process. (PNE is currently prioritizing recycling Li-ion batteries from everyday electronics over EVs.)

“The biggest change from 2020 to 2022 is that the EV market is very clear,” said Yan. “In 2020, if you talked to [people at General Motors], they would say ‘OK, we have EV cars, but we still have a big section of ICE — internal combustion engines.’ But right now, the GM CEO has already mentioned they will completely switch to EV in the next few years. The trend has completely changed.” The shifting market is set to bring millions of new EVs in the near future — and with them, millions of new batteries.

A processing plant at a lithium mine in Western Australia. (Shutterstock.com)

Modern Inefficiencies

Given the rapidly-growing EV market, the need for sophisticated Li-ion battery recycling has never been more urgent. “The lifetime of the batteries is between 5-10 years, so there’s a huge amount of wasted batteries,” said Yan. “How are we going to deal with them?” According to the Department of Energy, by 2030, 11 million metric tons of Li-ion batteries will have reached the end of their service lives.

Dr. Bruce Koel

The contemporary methods of Li-ion battery recycling currently used by major manufacturing industries are, unfortunately, unsustainable. Dr. Bruce Koel, professor of chemical and biological engineering at Princeton University, explained the two methods, the first being pyrolysis, “or smelting, where you basically  melt everything down and recover, eventually, the atomic components — the elements: the nickel, the cobalt, the lithium, and so forth.” The other, acid-leaching, involves “[dissolving] the materials of the battery into large vats of very aggressive acids, which is a low-temperature process but makes a tremendous amount of waste water.” (Koel is also a co-founder and technology adviser at PNE.) Currently, it’s hard to feel like recycling is worthwhile when both methods involve significant pollution as a byproduct.

Worse, even setting pollution aside, both processes are prohibitively inefficient: reclaiming lithium through recycling is five times more expensive than simply mining more. “It’s still cheaper to just mine new materials,” said Koel. “And that’s why there are these warehouses of millions of tons of used batteries that are just sitting there until somebody figures out what to do with them. People don’t want to put them in a landfill, but it’s too costly using the existing methods to recycle them. And it’s terribly harmful on the world — but that’s not why people aren’t doing it. It’s because it’s just not economical.” Seeing this emergent crisis and market for change, PNE got to work.

Comparison chart showing the current recycling of lithium batteries, left, versus the Princeton NuEnergy process, right. (Courtesy of PNE)

A Novel Approach

Dr. Xiaofang Yang

In 2019, Yan founded PNE with co-founders Koel, Dr. Xiaofang Yang, and Dr. Yiguang Ju. Koel and Ju, also a professor at Princeton University, serve on PNE’s advisory board. Yan serves as the CEO, and Yang as the CTO.

“The four of us founded this company and spun off from Princeton University,” said Yan. “Then we licensed the IP from Princeton University and continued to work on commercialization of recycling lithium-ion batteries.”

Combining their backgrounds in engineering (mechanical, chemical, and biological) and other fields, they listened to the industry’s needs and set out to address the Li-ion battery recycling problem.

PNE’s approach is a significant departure from contemporary melting methods. “We do something called direct recycling,” said Koel. Instead of breaking all the materials down to their base elements, direct recycling focuses on leaving still-functional parts of the battery intact.

Dr. Yiguang Ju

“We say it’s like if you had a Lego house and you wanted to build a castle. Well, you don’t have to take every Lego block apart and start over; you could use wall slab here or doorway opening here and start plugging it back in.” By focusing on preserving the materials, direct recycling is able to avoid many of the pollutant-heavy downfalls of other methods.

Not only is it cleaner than melting the materials, it also aims to be less expensive. “The bottom line is, people want to save money,” said Koel. “Now, there are a few people who want to put a poster up saying ‘We’re green,’ but the bottom line is that you’re going to have to be as cheap or cheaper than existing sources, otherwise nobody’s going to do it, frankly.”

One of the major potential savings areas for manufacturers is getting pa rtially-finished goods instead of base elements. “Instead of starting from this raw material from the mines and making cathodes again, and then building the battery, we would just sell them the replacement cathode material,” said Koel. “It’d be ready to go. And you cannot do that if you melt the battery components or dissolve them in acid.”

Deeds Over Words

From the start, PNE’s goal has been to not just theorize solutions, but to implement them. “At Princeton NuEnergy, we want to provide a faster, cleaner, and more sustainable solution to recycling lithium-ion batteries,” said Yan. “We want to not only have good technology, we want to build production lines to solve the real problem of the Li-ion batteries.”

With that focus in mind, PNE’s latest priority has been getting a proof-of-concept production line up and running in Dallas.

PNE isn’t the only group pursuing alternative Li-ion battery recycling methods, but they say their process sets them apart. Now it’s up to the pilot line to prove it. “The other companies, even in direct recycling, have amassed a fantastical amount of money, but they don’t have a process, or they’re using most of the old steps with maybe one new tweak,” said Koel. “Now, we need to make our pilot line work, because up to now we’ve worked at the kilogram scale. All that looks fantastic, but as everybody knows, the challenge is to run at scale.” PNE is targeting thousands of tons per year in the near future; “that’s a big jump.”

Matching the rapidly-expanding market for Li-ion batteries, PNE is gearing up for a scaled-up test run in a matter of months. “Currently, we already have our first production line — a building in Dallas — and hopefully in the future one or two months, this production will go live,“ said Yan. “This is a small production line. To us, it’s a big demo. We want to show the investors that this can solve industrial needs.”

If the test run performs well, PNE will look to gradually scale the process up to the tens of thousands of tons per year that industry requires.

99.9 percent fine lithium. (Shutterstock.com)

Looking Forward

Scaling to that highest capacity, like scaling any new technology, is expected to bring unforeseen challenges. Koel, though, remains optimistic. “I think our technology is — naively, I would say — easy to scale,” he said. “So I’m not anticipating a lot of problems, but there will be checks and proofs that we have to make. So we’ll see. But I don’t view this as a tremendous hurdle.”

Crystalizing their confidence, PNE has already been recognized with several monetary awards from national organizations — including a Phase 2 grant from the Department of Energy, something Koel points out as a good sign for investors. “That Phase 2 grant is a really nice little award to waive a flag about because they’re not easy to get. You have to have something that’s really on a good trajectory,” he said.

After years of research and development, it seems like PNE’s timing is on point.

“Today, in 2022, no one has any doubt about [the value of Li-ion recycling],” said Yan. “I faced a lot of challenges in 2020; at that time people were a bit hesitant about whether we even needed to recycle them or not. In 2022, right now we talked to all the EV OEMs (original equipment manufacturers). All of them think that recycling is necessary, and new technology is necessary. Right now they just need some time to digest and think about what we are doing — and the most important thing is that they want to see the pilot’s results.”

PNE should have all the data they need in about a year’s time, Until then, the market for lithium-ion batteries will continue to grow, whether there’s a process to deal with its byproducts or not.