ORNL researchers Lu Yu and Yaocai Bai examine vials that contain a chemical solution that causes the cobalt and lithium to separate from a spent battery, followed by a second stage when cobalt precipitates in the bottom. Credit: Carlos Jones/ORNL, U.S. Dept. of Energy
Department of Energy researchers recently improved lithium battery recycling approaches that rely on dissolving the battery in a liquid solution. The method reduces the hazardous chemicals used in the recycling process, providing a more sustainable means for lithium battery recycling.
Current methods for recycling lithium batteries involve dissolving shredded batteries or burning them. The most common method utilizes caustic inorganic acids and other chemicals to dissolve the shredded batteries which later are separated to recover critical materials contained in the solution.
The improved method developed by the Department of Energy’s Oak Ridge National Laboratory includes soaking the battery in a solution of organic citric acid and ethylene glycol. In the research, published in Energy Storage Materials, the team noted a strikingly efficient separation and recovery efficacy from the cathode of the battery.
“Because the cathode contains the critical materials, it is the most expensive part of any battery, contributing more than 30% of the cost,” said Yaocai Bai, a member of the ORNL battery research team. “Our approach could reduce the cost of batteries over time.”
The recycling solution successfully leached nearly 100% of the cobalt and lithium from the cathode of the batteries while not introducing any impurities to the materials.
“This is the first time one solution system has covered the functions of both leaching and recovery,” said lead researcher Lu Yu. “It was exciting to find that the cobalt would precipitate and settle out without further interference. We were not expecting that.”
The recycling method will not only provide a greener alternative to current recycling methods, but a more efficient process as well. “We were surprised by how quickly the leaching happened in our solution,” said Yaocai Bai. “With an organic acid, it usually takes 10-12 hours, but this took only one.” Conventional solutions using inorganic acid are also slower because they include water, which has a boiling point that limits the temperature of the reaction.