Recovery of lead and iodine from spent perovskite solar cells in molten salt

Organic-inorganic hybrid perovskite solar cells (PSCs) have received extensive attention due to their high power conversion efficiency, bright prospects for large-scale deployment, and low cost. However, the end-of-life lead (Pb)-based PSC will pose significant resource and environmental challenges. Herein, we develop an eco-friendly strategy, the molten-salt-electrolysis (MSE), to recover Pb and iodine (I2) from spent Pb-based PSC. First, lead iodide (PbI2) was dissolved in molten LiCl-KCl and then electrochemically converted into I2 at a graphite anode and Pb at the cathode. The recovery efficiency of Pb reached 97.65% with a high current efficiency of 96.87%. In addition, a high PbI2 leaching rate of ∼ 99.8% and a high PbI2 solubility of ∼ 5.97 wt.% in molten LiCl-KCl at 450 °C can sustain a rapid leaching and recovery process. Overall, MSE is a simple, rapid, and environmental-benign method to recover Pb-based PSCs, eliminating the Pb contamination and closing the iodine cycle.