Creating value added nano silicon anodes from end-of-life photovoltaic modules: recovery, nano structuring, and the impact of ball milling and binder on its electrochemical performance

Recovery of silicon from end-of-life photovoltaic (PV) modules, purification, conversion to nano silicon (nano-Si), and subsequent application as an anode in lithium-ion batteries is challenging but can significantly influence the circular economy. Currently, a complete technology consisting of cross-contamination-free recovery of silicon wafers from end-of-life PV modules, a low-cost environmentally friendly purification process of the recovered PV silicon, a high yield conversion process of the recovered PV silicon into nano-Si, and its subsequent application in lithium-ion batteries is unavailable. This study provides a complete package including cross-contamination-free recovery, economical purification, reliable conversion to nano-Si, and efficient application of the end-of-life PV nano-Si in lithium-ion batteries. Hydrofluoric acid-free recovery and purification processes are demonstrated which can deliver large quantities of high-purity (≥ 99) silicon. In addition, the subsequent ball milling process produces very distinct nano-Si with different shapes and sizes. This study also creates a very effective nano-Si anode through in-situ crosslinking of water-soluble carboxymethyl cellulose and poly (acrylic acid) precursors. The integration of distinct PV nano-Si and water-soluble carboxymethyl cellulose-poly (acrylic acid) crosslink binder opens distinct possibilities to develop silicon-based practical anode for next generation low-cost lithium-ion batteries to power cell phones to electric vehicles.