The recycling process of spent lithium-ion batteries mainly includes pretreatment, secondary treatment, and advanced treatment. Since spent batteries still retain some charge, the pretreatment process includes deep discharge, crushing, and physical sorting. The purpose of secondary treatment is to completely separate the positive and negative electrode active materials from the substrate, commonly achieved through methods such as thermal treatment, organic solvent dissolution, alkaline dissolution, and electrolysis. Advanced treatment mainly includes leaching and separation purification processes to extract valuable metal materials.
Based on the extraction process, lithium-ion battery recycling methods can be mainly divided into three categories: dry recycling, wet recycling, and biological recycling.
1. Dry recycling
Dry recycling refers to the direct recovery of materials or valuable metals without the use of solutions or other media. Important methods used include physical sorting and high-temperature pyrolysis.
2. Wet recycling
The wet recycling process involves crushing and dissolving waste batteries, then using appropriate chemical reagents to selectively separate metal elements from the leaching solution, producing high-grade cobalt metal or lithium carbonate, which are then directly recycled. Wet recycling is well-suited for recovering waste lithium-ion batteries with relatively simple chemical compositions. Its equipment investment costs are relatively low, making it suitable for small to medium-scale waste lithium-ion battery recycling. Therefore, this method is currently widely used.
3. Biological recycling
Mishra et al. used inorganic acids and Acidobacterium ferrooxidans to leach metals from spent lithium-ion batteries, and used S and ferrous ions (Fe2+) to generate metabolic products such as H2SO4 and Fe3+ in the leaching medium.
