Recycling Co and Li from spent lithium-ion batteries using the silicon of spent photovoltaic panels

Abstract

The rapid development of the energy sector has led to the generation of large quantities of spent lithium-ion batteries (LIBs) and spent photovoltaic (PV) panels. Effectively recycling these materials is crucial for resource utilization and environmental protection. Currently, recycling processes are conducted separately, increasing overall treatment costs. This study employs silicon recovered from spent PV panels as a reducing agent to facilitate the reduction of LiCoO₂ cathodes in spent LIBs. In this process, high-valence cobalt (Co³⁺) is reduced to low-valence cobalt (Co²⁺), while lithium is selectively leached as water-soluble Li₂SiO₃. The solid residue is further processed through wet magnetic separation to recover CoO/Co, effectively reducing the need for traditional solvent extraction and achieving efficient separation of Li and Co. Under optimal conditions (roasting at 700 °C for 30 minutes with a mass ratio of 20%), the recovery rates of Li and Co reached 95.32% and 97%, respectively. The reaction mechanism of silicon reduction roasting was analyzed using TG, XRD, SEM, and XPS characterization techniques. The reaction proceeded through a solid–solid mechanism, with no mass loss or gaseous pollutant emissions during the roasting process. The Li₂SiO₃ solution obtained from water leaching can be further processed by adding Na₂CO₃ to precipitate Li₂CO₃, which, together with the recovered CoO/Co product, can be used to re-synthesize LiCoO₂ cathodes. This approach presents a novel strategy for the co-recycling and resource utilization of waste materials.