Chinese researchers have developed a safe and efficient method to recover lithium from end-of-life lithium-ion batteries. Combining a carefully chosen solvent with a binding reagent, it’s possible to extract almost all available lithium. An additional advantage is that the resulting solutions can be used directly to make new batteries.
Most lithium recycling processes are targeted at extraction from cathodes, where most of the lithium in discharged batteries is located. However, it then precipitates out together with other metals contained in the cathode and must be painstakingly separated. Extraction from the anodes, which consist primarily of graphite, is significantly more efficient and can be carried out without discharging the battery beforehand. Because of their high reactivity, however, the risk of fires and explosions is high if the anodes are leached out with aqueous solutions, as is usual. These reactions release large amounts of energy and may produce hydrogen.
A team led by Yu-Guo Guo and Qinghai Meng at the Institute of Chemistry of the Chinese Academy of Sciences (ICCAS) and the University of Chinese Academy of Sciences (UCAS) has developed an alternative method that avoids these problems. Instead of water, they use so-called aprotic organic solutions to recover lithium from anodes. Aprotic substances can’t release any hydrogen ions, so no hydrogen gas can form. The solutions contain a polycyclic aromatic hydrocarbon, which can pick up lithium from the anode, but not any of the other metals present in a lithium-ion battery.