Lead is a problem, it’s highly toxic, it’s in a lot of stuff and still ends up in a landfills sometimes. One big source of lead is batteries, specifically car and and other vehicle batteries like golf carts. Thankfully lead can be used in a lot of things, like solar panels, particularly newer ones that use perovskite crystals. So MIT came up with a way to inexpensively recycle the heavy metal for use in these solar cells.
"When perovskite-based solar cells first came out, they were a few percent efficient," said Angela Belcher, the James Mason Crafts Professor in biological engineering and materials science and engineering at MIT. "Then they were 6 percent efficient, then 15 percent, and then 20 percent. It was really fun to watch the efficiencies skyrocket over the course of a couple years.” That’s great and all, but the most efficient perovskite solar cells to date, are lead-based.
New lead could be mined. “We thought, what if we got our lead from another source?,” Belcher said. Currently a lot of old car batteries are recycled into new batteries, but new battery technologies are likely to supplant lead-acid batteries in vehicles. “At that point, the 250 million lead-acid batteries in U.S. cars today will become waste—and that could cause environmental problems,” MIT said.
"If we could recover the lead in those batteries and use it to make perovskite solar cells, it'd be a win-win situation," Belcher said. They developed a simple, but safe, method of extracting the lead from car batteries for use in perovskite cells and other purposes.
To address the question of whether the lead iodide they harvested from the batteries was as good as that from chemical companies, Belcher and her colleagues made solar cells with the recycled materials compared them to those made with commercially available materials. “In a variety of tests, the films displayed the same nanocrystalline structure and identical light-absorption capability. Indeed, the films' ability to absorb light at different wavelengths was the same,” MIT said. The researchers admitted they weren’t experts at the technology, but Belcher said “People who are skilled in fine-tuning these solar cells to get 20 percent efficiencies would be able to use our material and get the same efficiencies.”
End result, they estimated how much recycled lead would be needed to meet U.S. electric demand using perovskite solar. “Powering the whole United States would take about 12.2 million recycled car batteries, fabricated into 8,634 square kilometers of perovskite solar panels operating under conditions similar to those in Nevada,” MIT said.Tweet