A system proposed by researchers at MIT recycles materials from discarded car batteries into new, long-lasting solar panels that provide emissions-free power. Lead acid car batteries are a potential source of lead pollution, which makes the idea a classic win-win solution.

The system is described in a paper in the journal Energy and Environmental Science, co-authored by professors Angela M. Belcher and Paula T. Hammond, graduate student Po-Yen Chen, and three others.

The solar cell idea for recycled lead 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.

Belcher, the W.M. Keck Professor of Energy at MIT said, “It went from initial demonstrations to good efficiency in less than two years.” Already, perovskite-based photovoltaic cells have achieved power-conversion efficiency of more than 19 percent, 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.

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

As an added advantage, 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.

Those factors will help to make it “easy to get to large scale cheaply,” Chen added.

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.

Chen noted, “The process to encapsulate them will be the same as for polymer cells today. That technology can be easily translated.”

Hammond noted, “It is important that we consider the life cycles of the materials in large-scale energy systems. And here we believe the sheer simplicity of the approach bodes well for its commercial implementation.”

Belcher pointed out one motivation for using the lead in old car batteries is that battery technology is undergoing rapid change, with new, more efficient types, such as lithium-ion batteries, swiftly taking over the market saying, “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.”

Today, she said, 90 percent 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.

Belcher believes that the recycled perovskite solar cells will be embraced by other photovoltaics researchers, who can now fine-tune the technology for maximum efficiency. The team’s work clearly demonstrates that lead recovered from old batteries is just as good for the production of perovskite solar cells as freshly produced metal.

Some companies are already gearing up for commercial production of perovskite photovoltaic panels, which could otherwise require new sources of lead. Since this could expose miners and smelters to toxic fumes, the introduction of recycling instead could provide immediate benefits, the team said.

This is good news for the solar cell industry. While the mining and recycling of lead is a minor issue in the developed world it remains a problem where employee safety and environmental pollution isn’t taken as seriously. Refined lead out in the environment is a really bad thing that justifies everyone keep an eye out and get those old batteries back in for recycling.


2 Comments so far

  1. Peter Wolstenholme on August 21, 2014 1:08 PM

    My personal opinion is that if the Blacklight Power “Suncell” becomes common, many systems, including motor vehicles, will still require batteries as a buffer store between the electricity generator and the load, but there will not be a need to get ultimate energy per pound ( or kg). So lead acid batteries might be useful for many years into the future, on grounds of cost. That would imply less use of Lithium based batteries in the future.
    But I have to admit that prediction is a tricky business, especially when it relates to the future.
    Peter W.

  2. jp straley on August 24, 2014 10:23 AM

    The danger from Pb is often overstated. That aside, Pb from car batteries is nowadays recycled with great efficiency.

    The invention you describe will have to stand on its own practicality and economics, not on being a serendipitous replacement for Pb otherwise used in batteries.

    One fact you did not mention that does bear on this discuss is that because Pb is so corrosion-resistant, it is stable and can be stockpiled for long periods of time.

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