Car batteries recycled into solar cells

Researchers from Massachusetts Institute of Technology (MIT) have developed a system which recycles materials from discarded car batteries into long-lasting perovskite solar panels, thus solving several environmental issues at once.

Perovskite is a compound which has rapidly progressed from initial experiments to a point where its efficiency is nearly competitive with that of other types of solar cells. Writing in the journal Energy and Environment Science, the researchers explained that organolead halide perovskite solar cells (PSCs) “show great promise as a new large-scale and cost-competitive photovoltaic technology … However, the manufacture of PSCs raises environmental concerns regarding the over-production of raw lead ore, which has harmful health and ecological effects.”

By using recycled lead from old car batteries, manufacturers could divert toxic material from landfills and re-use it in photovoltaic panels. This is particularly important as more efficient types of battery technology, such as lithium-ion batteries, take over the market.

“Once the battery technology evolves, over 200 million lead-acid batteries will potentially be retired in the United States, and that could cause a lot of environmental issues,” said study co-author Professor Angela M Belcher. She added that 90% of the lead recovered from the recycling of old batteries is currently used to produce new batteries, but as the market for new lead-acid batteries declines, this will potentially leave a large stockpile of lead with no obvious application.

In a perovskite solar panel, the lead-containing layer would be fully encapsulated by other materials, limiting the risk of lead contamination of the environment. As noted by co-author Po-Yen Chen, “The process to encapsulate them will be the same as for polymer cells today.”

The researchers stated that perovskite films assembled from recycled battery materials “show the same material characteristics (ie, crystallinity, morphology, optical absorption and photoluminescence properties) and identical photovoltaic performance (ie, photovoltaic parameters and resistances of electron recombination)” as high-purity commercial reagents. When the panels are eventually retired, the lead can simply be recycled into new solar panels.

As the perovskite photovoltaic material takes the form of a thin film just half a micrometre thick, the lead from a single car battery could produce enough solar panels to provide power for 30 households. Additionally, said Professor Belcher, the production of perovskite solar cells “has the advantage of being a low-temperature process, and the number of steps is reduced” compared with the manufacture of conventional solar cells.

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