Scientists at Oak Ridge National Laboratory (ORNL) have developed a solvent that enables a “more environmentally friendly” process for recycling lithium-ion batteries.
The ORNL-developed wet chemical process uses triethyl phosphate to dissolve the binder material that adheres cathodes to metal foil current collectors in lithium-ion batteries.
The method can recover cobalt-based cathodes, graphite and other valuable materials like copper foils for reuse in new batteries.
Oak Ridge National Laboratory researcher Yaocai Bai told BEST: "We are working with the battery industry and several companies are interested in this patented technology.
"The pyrometallurgical process involves the high energy cost of using high-temperature kilns and the detrimental generation of gaseous pollutants. The hydrometallurgical process involves caustic reagents and wastewater treatment. In contrast, our method utilises a green solvent that can be recycled and reused, making the process more environmentally friendly.
"The cost of this process is currently being evaluated. We are using the EverBatt model developed by the DOE ReCell Center to study both the cost and environmental aspects of our process. We believe the cost is low because of the reusability of the green solvent."
The use of, triethyl phosphate enabled the recovery of cobalt-containing cathodes, such as NMC622, by dissolving the polymeric binder of poly (vinylidene fluoride).
Electrochemically active materials were separated from cathode scraps collected at the manufacturing step of electrodes through a solvent-based separation method without jeopardizing their physical characteristics, crystalline structure, and electrochemical performance.
The team reported the recovered aluminum foils had no sign of corrosion and the polymeric binder could be recovered via a non-solvent-induced phase separation.
Additionally, recovery of cathode materials from spent cells was achieved using refined separation parameters based on the recycling of cathode scraps.
ORNL’s Ilias Belharouak said: “With this solvent, we’re able to create a process that reduces toxic exposure for workers and recovers valuable, undamaged, active NMC [nickel-manganese-cobalt] cathodes, clean metal foils and other materials that can be easily reused in new batteries.”
To date, the tem has only tested the technology on a "few kilograms" of battery scrap.