According to foreign media reports, in the German journal "Applied Chemistry" (Angewandte Chemie), Chinese researchers introduced a new method to recover lithium from used lithium-ion batteries.
Recycling lithium-ion batteries is a difficult task, and the process of recovering high-quality lithium for reuse is complex and expensive. The goal of most recycling processes is to extract lithium from the cathode, where most of the lithium is located when the battery is discharged. However, this lithium precipitates with other metals in the cathode and is difficult to separate.
Extraction of lithium from the anode (which consists primarily of graphite) is significantly more efficient and can be performed without pre-discharging the battery. However, due to the high reactivity, there is a high risk of fire and explosion if the lithium in the anode is leached from an aqueous solution as usual. These reactions can release large amounts of energy and produce hydrogen.
The team headed by Yuguo Guo and Qinghai Meng at the Institute of Chemical Sciences of the Chinese Academy of Sciences (ICCAS) and the University of Chinese Academy of Sciences (UCAS) has now developed an alternative method that avoids these problems. Instead of water, the researchers used a non-protonic organic solution to recover lithium from the anode. Non-protonic substances cannot release any hydrogen ions and therefore cannot form hydrogen gas.
The solution consists of polycyclic aromatic hydrocarbons (PAHs) and ether as a solvent. Some PAHs can absorb positively charged lithium ions and an electron from the graphite anode. Under mild conditions, this redox reaction is controlled and very efficient. Using the PAH pyrene in tetraethylene glycol dimethyl ether, the active lithium in the anode can be almost completely dissolved.
Another advantage is that the resulting lithium-PAH solution can be used directly as a reactant, e.g. to add lithium to a new anode when pretreating or regenerating a spent cathode.The PAH/solvent system can be adapted to be optimised for the material being processed.
This efficient and cost-effective recycling process not only reduces safety risks but also helps to avoid waste and opens up new perspectives for sustainable recycling of lithium-ion batteries.
