MIT Engineers have developed a way to utilize lead from old car batteries to make perovskite solar cells.

Traditionally, lead in car batteries is recycled. However, lead-free car batteries are becoming more popular, which means used batteries could end up in landfills, posing an environmental and health risk.

MIT calculates that the 250 million lead car batteries used in the United States today do not have to go to waste. Instead of sending the discarded batteries to landfills they could be sent to the solar industry.

Are there Environmental Risks of Lead Based Solar Cells?

How to synthesize lead iodide perovskite from a lead-acid battery (Image courtesy of MIT.)

Perovskites, a class of crystalline photovoltaic materials, have been receiving much attention in the solar community for their high efficiency.

The biggest drawback with perovskite cells, however is that they contain lead.

Fortunately, MIT reports that we will not need to increase dangerous lead mining and smelting operations to meet demand. This is because solar cells created with lead from discarded car batteries work just as well as cells made with freshly mined materials.

To see how MIT recycles the lead from batteries, watch this video:

Does Recycled Lead Affect Solar Cell Performance?

Chart comparing high-purity commercial lead to recycled lead from a car battery. (Image courtesy of MIT.)

The next question any engineer worth their precipitate will ask is ‘how will the quality of recycled lead compare to high-purity lead from smelters?’ Researchers compared the two.

Results comparing the lead source and the light-harvesting ability of perovskite showed that the nanocrystalline structure, with the ability to retain light at different wavelengths and light-absorption proficiency, showed little change.

Testing also showed that photovoltaic performance was nearly identical between the samples.

To ensure these results were consistent, researchers continued their testing with three more batteries with various life cycles. The individual batteries were in operation between six months and four years.

The results from the second round of testing were similar, with one difference. The older the car battery, the more likely the lead would be in the form of lead sulfate. The team adapted by devising a process to recover the lead from lead sulfate.

During testing, recycled lead also showed that it could be incorporated into other processes that were used to create perovskite-based solar cells as well as to make other kinds of solar cells that include lead, light-emitting diodes, piezoelectric devices and more.

Are these Solar Cells Economical?

Results from an economic analysis proved the procedure to be economically viable. MIT calculated that 700 square meters of perovskite solar cells could be produced from one lead-acid car battery, assuming the thin film was a micrometer thick.

If the cells were to reach a 15 percent efficiency, which MIT reports is a conservative estimate, the cells could generate enough electricity to power roughly 30 homes in Las Vegas.

To generate enough electricity to power the United States it would take lead from around 12.2 million recycled car batteries to create 8,634 square kilometers of perovskite solar panelling. This is less than five percent of the lead car batteries currently in use.

Ideally the best case scenario would be to find an effective and nontoxic replacement for the lead altogether. MIT reports that research for a more effective replacement continues.

For more updates on green studies at MIT, visit their website.