Efficient recycling of metals from solar cells using catalytic etchants

Due to the recent trend towards increasing renewable energy production, a large proportion of this demand will be addressed by solar energy. This greater consumption of solar cells will inevitably result in an equally large amount of end-of-life material that should be recycled to recover the valuable metal components. In the present work, the dissolution of silver and aluminium from silicon solar cells was investigated using copper(II) chloride and iron(III) chloride as redox catalysts, dissolving up to 95% of the target metals within 10 min. A mixed hydro- and ionometallurgical approach was taken, with a 2-step selective leaching process. Initially, aluminium and other lower value metals are removed using iron(III) or aluminium(III) chloride in water, with the help of ultrasound to delaminate the aluminium layer. Silver is then leached using iron(III) chloride in a choline chloride: water brine. A high recovery of silver (95%) with high purity (98 wt%) is possible just by adding water to the leach liquor to precipitate silver chloride. Use of brines for the processing of metals is a new and interesting approach to replace mineral acids by cheaper and environmentally friendlier solvents.