The electric vehicle (EV) era is just beginning, but the problem of battery waste is already becoming too hard to ignore.

Battery recycling technology has been around for decades, but it is time and energy intensive and difficult to scale. Princeton NuEnergy, a spin-off from Princeton University, has devised a solution that could help.

The “dead battery” problem.

According to one BBC report550,000 electric vehicle (EV) batteries reached the end of their life in 2020. The life cycle of these batteries began when the adoption of electric vehicles had not yet taken off. By 2035, this number is expected to reach 150 million.

The Environmental Protection Agency (EPA) classifies lithium-ion batteries as hazardous waste. When disposed of at the end of their life cycle, they are more likely to explode or catch fire if not handled properly.

If left untreated, batteries also end up in landfills, where they can leach toxic chemicals that contaminate groundwater and soil, posing a health risk to nearby communities. The EPA recommends recovering the chemicals from used batteries because they can be reused.

For example, sourcing one ton of lithium from natural resources requires 250 tons of ore and generates 750 tons of brine. In stark contrast, only 28 tons to use lithium-ion batteries can generate a ton of high quality lithium that can be used again in batteries.

How are batteries recycled?

A common approach to recycling is shredding, where part or all of the battery is shredded after it has been completely discharged. This generates streams of different materials such as plastics, electrolytes, steel, copper, aluminum and black mass – granular material that contains crushed cathodes and anodes and is then used to make cathodes and anodes for new batteries.

Two methods can be used to recover materials from the black mass: pyrometallurgy, where heat is used to melt the metals from the mass, and hydrometallurgicalwhere the liquid is used to remove metals.

However, these approaches have problems of low selectivity and emissions of toxic gases such as nitrous oxide and sulfur dioxide. Pyrometallurgical reactions occur at temperatures up to 2,912 degrees Fahrenheit (1,600 degrees Celsius), requiring the use of fossil fuels. Hydrometallurgy may not require higher temperatures, but still suffers from incomplete recovery of metals and overuse of minerals to facilitate recovery.

With only five percent of batteries currently recycled, increased recycling efforts are needed as battery waste is expected to increase over the next decade. However, recycling processes need to be more efficient for large-scale recycling to be effective.

The US Department of Energy has been keen to explore newer technologies for battery recycling beyond heat and liquid based approaches. This is where Princeton New Energy’s plasma-based recycling technology can help.

The approach follows the same separation and comminution steps as conventional battery recycling, but uses low-temperature plasma-assisted separation (LPAS) instead of energy-consuming steps.

Low temperature plasma assisted separation

Before implementing the LPAS step, battery components such as copper, aluminum, plastic, cathode and anode are separated. Only the cathode and anode enter the LPAS stage, where they can be rejuvenated after removing surface impurities.

“Unlike hydro/pyro processes that turn aged cathode materials into chemicals by acid leaching, LPAS uses low-temperature plasma to create highly reactive species (electrons, ions, atoms) that remove surface impurities and activate the materials for rejuvenation later,” Xiaofang explained. Yang, co-founder and chief technology officer at Princeton New Energy, in an email to Interesting engineering.

While plasma is usually associated with high temperature, PNE plasma is low temperature, achieved by keeping the molecular temperature low but the electron temperature high. “This is achieved by controlling the discharge power, pressure and design of the plasma reactor, not by burning fossil fuels,” Yang added.

The patented technology provides rejuvenated battery-grade cathode and anode materials that are on par with those from natural resources and meet the quality standards set by original equipment manufacturers (OEMs).

Essential to providing high-quality materials from the recycling process is the retition of the electrode materials. PNE accomplishes this through a process referred to as Molten Micro-Shell Assisted Lithiation, or MSAL.

“MSAL repairs the structure, composition and function of aged cathode materials, which often have less lithium and poor electrochemical performance after long-term cycling,” explained Yang.

“The rejuvenation step involves fine control of the lithiation media where a micro-coating of lithium is formed on the surface of the material, resulting in uniform and complete recovery.”

Advantages of LPAS

The recovery rate achieved using this approach is up to 95%, but it also improves costs and environmental outcomes. According to the company, LPAS offers a 73% reduction in energy consumption and a 69% reduction in carbon dioxide emissions compared to conventional mining, while also using 69% less water.

“Our direct recycling method aims to be cost competitive by reducing energy and chemical consumption compared to traditional methods. Overall, it offers a 38% reduction in production costs compared to virgin cathode active material (CAM) production,” Yang said.

“We reduce costs by not using acid leaching, needing less lithium in our recycling process and less energy consumption, carbon emissions and waste handling, which lowers our operating costs.”

“Cost savings from eliminating disposal expenses should be factored into the overall return on investment (ROI),” explained Jon M Williams, CEO of Viridi, a US energy storage solutions provider. “Of recycling instead of dumping, companies can avoid the rising costs of handling hazardous waste, which adds an important financial incentive to the equation.”

While conventional techniques such as hydrometallurgy struggle with changing electrode composition as battery technology matures, LPAS has been shown to work in battery technologies such as nickel cobalt manganese (NCM) and nickel cobalt aluminum oxide ( NCA) widely used. in electric vehicles.

The technology has been shown to work effectively for lithium iron phosphate (LFP) batteries currently used in electric vehicles and lithium cobalt oxide (LCO) batteries used in consumer electronics.

Under test conditions, the recycling technology provided 83.66% discharge capacity retention in LCO batteries and 88.9% in NCM batteries after over 1,000 deep cycles. This is on par with the performance of Li-ion batteries made from virgin materials.

Increasing battery recycling

After responding to the DOE’s call for innovative battery recycling technologies in 2017, Princeton researchers explored the use of low-temperature plasma, decided to commercialize the technology, and founded PNE.

As part of its commercialization efforts, the team built a prototype at Princeton’s chemical and biological engineering facility. After demonstrating significant potential, PNE is establishing the first US commercial lithium-ion battery direct recycling facility in South Carolina.

The facility, which is expected to be operational by the third quarter of 2028, is designed to produce 10,000 tonnes of CAM for batteries each year, equivalent to producing batteries for more than 100,000 electric vehicles annually.

“We have agreements with several companies to supply recycled batteries, ensuring a constant raw material for our recycling,” Yang added in an email to IE.

The road ahead

The need for battery recycling has been identified and several research groups have worked to solve this problem. Interesting Engineering regularly reports on new approaches to how recycling could be speeded up or made more efficient.

However, the challenge is scaling up the technology. UK company Altilium has also announced plans to produce batteries from used EV batteries, signaling that the technology is now mature enough to be scaled up and deployed.

The next level proves that recycling also works economically.

“When you also factor in the elimination of disposal costs, recycling offers a strong ROI opportunity that could significantly improve the economics of lithium-ion cell recovery,” Williams explained to IE.

“Ultimately, for any of these technologies to be successful, they must scale efficiently and generate more value from the recovered materials than the total costs of plant, equipment and operations.”

Even upon investigation, PNE did not disclose the cost aspects of its ambitious project or when it was likely to break even. “Our mission is to be equal to or better than OEM quality cathode materials at a lower cost than original battery materials,” added Yang. He claimed that the cost of recycling batteries is confidential information.