A domestic research team has developed a recycling technology that recovers nickel and cobalt from spent batteries at ultra-high purity of 99% with a recovery rate of more than 95%.
A research team led by Kim Gwi-yong, a professor in the Department of Earth Environmental and Urban Construction Engineering at Ulsan National Institute of Science and Technology (UNIST), said on the 28th that it succeeded in selectively separating and recovering nickel and cobalt from spent batteries using an electrochemical process that employs a multifunctional special solvent. The results were published on the 2nd (local time) in the international journal Energy Storage Materials.
Spent batteries are called a "urban mine" because they contain large amounts of strategic metal resources such as nickel, cobalt, and manganese, but it is difficult to separate and use them because multiple metals are mixed together. Strong acids such as sulfuric acid and chemical extractants must be used, which not only generate hazardous wastewater but also lower energy efficiency due to multistage processes.
The electrochemical process developed by the research team can minimize the use of chemicals and the generation of wastewater while increasing both purity and recovery rate through a single process. It involves passing electricity while changing the voltage through a solution in which spent battery powder is dissolved, precipitating metals in ionic form into solid metals. The technology exploits the principle that each metal ion has a different voltage at which it precipitates into a solid.
Nickel and cobalt, which account for about 50% of battery manufacturing costs, have the problem of co-precipitating at similar voltages, which was solved by using a special solvent (eutectic solvent). The ethylene glycol component of the special solvent binds to nickel ions, and the chloride component binds to cobalt ions, respectively, changing the voltages at which the two metal ions precipitate into solids. As a result, nickel is separated and extracted at −0.45V, and cobalt at −0.9V.
In addition, chlorine components that naturally occur during the process selectively re-dissolve only cobalt that has mixed in as an impurity, allowing the nickel separation purity to be increased without a separate refining process. The chlorine used to dissolve cobalt is ionized into hydrochloric acid ions, so there is no concern about atmospheric emissions, and the hydrochloric acid component accumulated in the solvent can be regenerated into pure hydrochloric acid for reuse.
When the technology was applied to commercial NCM (nickel, cobalt, manganese) spent batteries, both nickel and cobalt were separated at high purity levels of up to more than 99.9%, and both metals recorded recovery rates of more than 95%. The special solvent used maintained its performance even after being reused more than four times, minimizing wastewater generation.
Professor Kim Gwi-yong said, "We simultaneously solved the trade-off between purity and recovery rate, which had been a chronic limitation of electrochemical separation," and noted, "By minimizing the use of chemicals and the generation of wastewater while ensuring economic feasibility, this will help build a sustainable battery circular economy."
References
Energy Storage Materials (2025), DOI: https://doi.org/10.1016/j.ensm.2025.104646