The era of electric vehicles (EVs) is just beginning, but the problem of waste from batteries is already becoming very difficult to ignore.

Battery recycling technology has been around for decades but is time- and energy-intensive and difficult to scale. Princeton NuEnergy, a spinoff of Princeton University, has designed a solution that can help.

‘Depleted battery’ problem

According to a BBC reportIn 2020, 550,000 electric vehicle (EV) batteries reached end of life. The lifecycle of these batteries began before EV adoption had even begun. This number is expected to reach 150 million in 2035.

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 leach toxic chemicals that contaminate groundwater and soil, posing a health risk to nearby communities. The EPA recommends recycling chemicals from used batteries because they can be reused.

For example, to obtain one ton of lithium from natural resources, 250 tons of ore is required and 750 tons of brine are produced. On the contrary, only 28 tons were used lithium ion batteries It could produce a ton of high-quality lithium that could be reused in batteries.

How are batteries recycled?

A common approach to recycling is shredding, in which part or all of the battery is broken down after it is completely discharged. This produces streams of different materials such as plastic, electrolyte, steel, copper, aluminum and black mass, which contain fragmented cathodes and anodes and are then used to make cathodes and anodes for new batteries.

Two methods can be used to recover material from the black mass: pyrometallurgy, in which heat is used to melt metals from the mass, and hydrometallurgywhere liquid is used to leach metals.

However, these approaches have problems such as low selectivity and the emission of toxic gases such as nitrous oxide and sulfur dioxide. Pyrometallurgy reactions occur at temperatures as high as 2,912 degrees Fahrenheit (1,600 degrees Celsius), requiring the use of fossil fuels. Hydrometallurgy may not require higher temperatures, but it still encounters problems such as incomplete metal recovery and excessive use of minerals to facilitate recovery.

With only five percent of batteries currently being recycled, there is a need to increase recycling efforts as battery waste is expected to increase in the next decade. However, for large-scale recycling to be effective, recycling processes must be more efficient.

The U.S. Department of Energy is eager to explore newer technologies for battery recycling beyond heat and liquid-based approaches. That’s where Princeton New Energy’s plasma-based recycling technology can help.

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

Low temperature plasma assisted separation

Before applying the LPAS step, battery components such as copper, aluminum, plastic, cathode and anode are separated. Only the cathode and anode enter the LPAS step, where they can be regenerated after removal of surface impurities.

“Unlike hydro/pyro processes, which convert old cathode materials into chemicals by acid leaching, LPAS uses low-temperature plasma to create highly reactive species (electrons, ions, atoms) that remove impurities from the surface and activate the materials for subsequent rejuvenation,” explained Xiaofang. . Yang, co-founder and Chief Technology Officer of Princeton New Energy, said in an email. Interesting Engineering.

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

The patented technology delivers battery-grade regenerated cathode and anode materials that are on par with those derived from natural sources and meet quality standards set by original equipment manufacturers (OEMs).

Reprocessing of electrode materials is very important to obtain high-quality materials from the recycling process. PNE achieves this through a process it calls Micro Melted Shell Assisted Lithiation, or MSAL.

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

“The rejuvenation step involves precise control of lithiation environments, where a micro lithium shell forms on the surface of the material, leading to uniform and complete reprocessing.”

Advantages of LPAS

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

“Our direct recycling method aims to be cost competitive by reducing energy and chemical consumption compared to traditional methods. It overall provides a 38% reduction in production costs compared to the production of virgin Cathode Active Material (CAM),” said Yang.

“We reduce costs by not using acid leaching, requiring less lithium in our recycling process, and reducing our operating costs with less energy consumption, carbon emissions and waste processing.”

“Cost savings achieved by eliminating disposal expenses should be factored into the overall return on investment (ROI),” said Jon M Williams, CEO of Viridi, a US-based energy storage solutions provider. “With recycle “Companies can avoid the increasing costs of treating hazardous waste rather than disposing of it, adding a significant financial incentive to the equation.”

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

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

Under test conditions, the recycling technology achieved a discharge capacity retention of 83.66% in LCO batteries and 88.9% in NCM batteries after more than 1,000 deep cycles. This is the same performance as Li-ion batteries made from virgin materials.

Increasing battery recycling

After responding to 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.

The team built a prototype facility at Princeton’s Chemical and Biological Engineering facility as part of its commercialization efforts. After demonstrating significant potential, PNE is building the first US commercial-scale lithium-ion battery direct recycling facility in South Carolina.

The facility, which is expected to be operational by the 3rd quarter of 2028, is designed to produce 10,000 tonnes of battery-grade CAM each year, equivalent to the production of batteries for more than 100,000 electric vehicles.

“We have agreements with multiple companies to supply recycled batteries, providing a stable raw material for our recycling,” Yang added in his email. I.E..

The road ahead

The need for battery recycling was identified and many research groups worked to solve this problem. Interesting Engineering regularly reports on new approaches on how recycling can be accelerated or made more efficient.

But the challenge is to scale up the technology. UK-based company Altilium has also announced plans to produce batteries from used EV batteries, showing signs that the technology is now mature enough to be scaled up and put into use.

The next stage is to show that recycling also works economically.

“When you also factor in the elimination of disposal costs, recycling offers a strong return on investment opportunity that can significantly increase the economics of lithium-ion cell recovery,” Williams explained. I.E..

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

Even upon inquiry, PNE did not disclose the cost aspects of its large-scale project or when the break-even point would occur. “Our mission is to be equal to or better than OEM-grade cathode materials at a lower cost than original battery materials,” Yang added. He claimed that the cost of recycling batteries was confidential information.