Controlled phase transformation and purification of spent lead acid batteries into electronic-grade PbI2 for all-perovskite tandem solar cells

Industrial spent lead paste is upcycled into electronic-grade PbI 2 . • Phase convergence enables selective Pb leaching while retaining impurities. • Kilogram-scale processing achieves 95.12% overall Pb recovery and 99.9925% purity. • Upcycled PbI 2 enables 20.51% wide-bandgap and 28.65% tandem efficiencies. • Life-cycle and techno-economic analyses show environmental and economic gains. Upcycling spent lead-acid batteries into photovoltaic precursors offers a route to couple mature batteries recycling infrastructure with the growing material demand of perovskite photovoltaics. Here, we develop an upcycling strategy that converts industrial spent lead paste into electronic-grade PbI 2 for all-perovskite tandem solar cells. The process transforms chemically heterogeneous PbSO 4 , PbO 2 , PbO and metallic Pb into a uniform PbO intermediate, followed by pH controlled acetic acid leaching that selectively dissolves Pb 2 + while retaining major impurity components in the solid residues. Subsequent iodide precipitation yields PbI 2 with a measured purity of 99.9925%. Kilogram-scale production achieves an overall Pb recovery of 95.12%, demonstrating that the reaction selectivity and product quality can be retained during scale-up. Compared with low-purity recycled PbI 2 , the purified product improves precursor solubility, film morphology and carrier lifetime, enabling a wide-bandgap perovskite solar cell efficiency of 20.51%. The recycled PbI 2 enables all-perovskite tandem solar cells with an efficiency of 28.65%. Combined life-cycle and techno-economic analyses demonstrate that this strategy offers a practical route for transforming industrial battery waste into photovoltaic materials. Download: Download high-res image (149KB) Download: Download full-size image