German researchers have converted 17th-century musket balls into high-purity lead iodide for perovskite solar cells, achieving a 94% electrochemical conversion efficiency.
The process, developed by teams at the Jülich Research Centre and Friedrich-Alexander University of Erlangen-Nuremberg, involves melting the historical ammunition and reforming it into electrodes before subjecting it to an electrochemical treatment in acetonitrile with dissolved iodine.
This method not only purifies lead contaminated with carbon residues, metallic inclusions, and oxidation patina but also boosts overall performance by 204% compared to the original material, according to the study published in Cell Reports Physical Science.
Perovskite solar cells have long promised cheaper, more flexible alternatives to silicon-based panels, with laboratory efficiencies exceeding 26%, but their reliance on high-purity lead iodide has been hindered by the environmental and energetic costs of mining and refining new lead.
Last time a similar approach was attempted—using recycled industrial lead for solar materials—the purification steps required strong acids and large water volumes, making the process unsustainable at scale.
Ian Marius Peters, a coauthor of the study, noted that millions of tons of lead remain underutilized in waste streams, presenting a vast resource if recovery methods can meet photovoltaic purity standards.
The technique avoids traditional acid-based purification, instead using a two-stage electrochemical and crystallization process that significantly reduces hazardous waste and energy input.
Even as perovskite cells still face challenges in long-term stability under heat and humidity, this breakthrough addresses a critical bottleneck in sustainable material sourcing for next-generation solar technology.
How does the electrochemical process work?
Researchers first melt the musket balls and shape them into electrodes, then immerse them in an acetonitrile solution with dissolved iodine and apply an electric current to generate lead iodide, which is later purified to photovoltaic grade.
Why use historical ammunition as a lead source?
The lead in centuries-old musket balls, though degraded and impure, represents an abundant waste stream that, when purified through this method, can yield material comparable to commercially sourced lead iodide without new mining.