Princeton turns empty EV batteries into gold

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

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

The ‘spent battery’ problem

According to one BBC reportIn 2020, 550,000 electric vehicle (EV) batteries reached end of life. The life cycle of these batteries started when the adoption of electric vehicles was not yet taking off. By 2035, this number is expected to rise to as many as 150 million.

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

If batteries are not treated, they also end up in landfills, where they can leak toxic chemicals that contaminate groundwater and soil, posing a health risk to nearby communities. The EPA recommends recovering chemicals from used batteries because they can be reused.

For example, obtaining one ton of lithium from natural resources requires 250 tons of ore and produces 750 tons of brine. In stark contrast, only 28 tons were used lithium-ion batteries can generate one ton of high-quality lithium that can be reused in batteries.

How are batteries recycled?

A common approach to recycling is shredding, which involves shredding part or all of the battery after it has been fully discharged. This creates currents of various materials, such as plastics, electrolytes, steel, copper, aluminum and black mass: granular material that contains shredded 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, which uses heat to melt metals from the mass, and hydrometallurgywhere liquid is used to leach metals.

However, these approaches pose problems in terms of low selectivity and the emission of toxic gases such as nitrous oxide and sulfur dioxide. Pyrometallurgical reactions take place 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 suffers from incomplete metal recovery and excessive mineral use to facilitate recovery.

With only five percent of batteries currently recycled, there is a need to increase recycling efforts as battery waste is expected to increase over 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 battery recycling technologies that go beyond heat and fluid-based approaches. This is where Princeton New Energy’s plasma-based recycling technology can help.

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

Plasma-assisted separation at low temperature

Before the LPAS step is initiated, 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 rejuvenated after removing surface impurities.

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

Although plasma is usually associated with high temperatures, the plasma of PNE has a 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 delivers battery-quality rejuvenated cathode and anode materials that are comparable to materials sourced from natural resources and meet Original Equipment Manufacturers (OEMs) quality standards.

Crucial to delivering high-quality materials from the recycling process is the relithiation of the electrode materials. PNE achieves this through a process it calls Micro-Molten Shell-Assisted Lithiation, or MSAL.

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

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

Benefits of LPAS

The recovery rate achieved with this approach is as high as 95 percent, but it also improves costs and environmental outcomes. According to the company, LPAS offers a 73 percent reduction in energy consumption and a 69 percent reduction in CO2 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 generally offers a 38% reduction in production costs compared to the production of virgin cathode active material (CAM),” Yang said.

“We reduce costs by eliminating acid leaching, requiring less lithium in our recycling process and using less energy, carbon emissions and waste disposal, reducing our operating costs.”

“The cost savings from eliminating disposal costs must be factored into the overall return on investment (ROI),” explains Jon M Williams, CEO of Viridi, a US-based energy storage solutions provider. “By means of recycling Instead of throwing it away, companies can avoid the growing costs of handling hazardous waste, adding an important financial incentive to the equation.”

While conventional techniques such as hydrometallurgy struggle with the changing composition of electrodes as battery technology matures, LPAS has been shown to work on battery technologies such as nickel, cobalt and manganese (NCM) and nickel, cobalt and alumina (NCA), which are largely in use. in electric vehicles.

The technology has been shown 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 maintained discharge capacity of 83.66% for LCO batteries and 88.9% for NCM batteries after more than 1,000 deep cycles. This corresponds to the performance of Li-ion batteries made from new materials.

Scaling up 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 the commercialization efforts, the team built a prototype facility at Princeton’s Chemical and Biological Engineering facility. After demonstrating significant potential, the PNE is setting up the first commercial-scale direct recycling facility for lithium-ion batteries in the US in South Carolina.

The facility, which is expected to come online in the third quarter of 2028, is designed to produce 10,000 tons of battery-level CAM annually, equivalent to producing batteries for more than 100,000 electric vehicles per year.

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

The way forward

The need for battery recycling has been identified and multiple research groups have been working to solve this problem. Interesting Engineering regularly reports on new approaches to how recycling can be accelerated or made more efficient.

The challenge, however, is scaling up the technology. British company Altilium also announced plans to produce batteries from used EV batteries, indicating that the technology is now mature enough to be scaled up and rolled out.

The next level is to demonstrate that recycling is also economical.

“When you also consider eliminating disposal costs, recycling offers a powerful ROI opportunity that could significantly improve the economics of lithium-ion cell recovery,” Williams explains. I.E.

“For all of these technologies to succeed, they must ultimately scale effectively and generate more value from the recovered materials than the total cost of the plant, equipment and operations.”

Even after enquiries, PNE did not disclose the cost aspects of its large-scale 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,” Yang said. He claimed that battery recycling costs were confidential information.