old batteries recycled into new solar cells

Researchers have proposed a system that recycles materials from discarded car batteries — a potential source of lead pollution — into new, long-lasting solar panels that provide emissions-free power.

The system is based on a recent development in solar cells that makes use of a compound called perovskite — specifically, organolead halide perovskite — a technology that has rapidly progressed from initial experiments to a point where its efficiency is nearly competitive with that of other types of solar cells.

"It went from initial demonstrations to good efficiency in less than two years," said Angela M Belcher, the W M Keck Professor of Energy at Massachusetts Institute of Technology.

Already, perovskite-based photovoltaic cells have achieved power-conversion efficiency of more than 19 per cent, which is close to that of many commercial silicon-based solar cells.

Initial descriptions of the perovskite technology identified its use of lead, whose production from raw ores can produce toxic residues, as a drawback.

But by using recycled lead from old car batteries, the manufacturing process can instead be used to divert toxic material from landfills and reuse it in photovoltaic panels that could go on producing power for decades.

Since the perovskite photovoltaic material takes the form of a thin film just half a micrometre thick, the team's analysis shows that the lead from a single car battery could produce enough solar panels to provide power for 30 households.

The production of perovskite solar cells is a relatively simple and benign process.

"It has the advantage of being a low-temperature process, and the number of steps is reduced compared with the manufacture of conventional solar cells," Belcher said.

Today, Belcher said, 90 per cent of the lead recovered from the recycling of old batteries is used to produce new batteries, but over time the market for new lead-acid batteries is likely to decline, potentially leaving a large stockpile of lead with no obvious application.

In a finished solar panel, the lead-containing layer would be fully encapsulated by other materials, as many solar panels are today, limiting the risk of lead contamination of the environment.

When the panels are eventually retired, the lead can simply be recycled into new solar panels.

The work clearly demonstrates that lead recovered from old batteries is just as good for the production of perovskite solar cells as freshly produced metal, researchers said.

The study is published in the journal Energy and Environmental Science.