Researchers at MIT have devised an environmentally-responsible process to recycle materials from discarded automotive lead-acid batteries to fabricate efficient organolead halide perovskite solar cells (PSCs)—a promising new large-scale and cost-competitive photovoltaic technology. The process simultaneously avoids the disposal of toxic battery materials and provide alternative, readily-available lead sources for PSCs.
The system is described in a paper in the RSC journal Energy and Environmental Science, co-authored by professors Angela M. Belcher and Paula T. Hammond, graduate student Po-Yen Chen, and three others.
Perovskite films, assembled using materials sourced from either recycled battery materials or high-purity commercial reagents, show the same material characterizations (i.e., crystallinity, morphology, optical absorption, and photoluminescence property) and the identical photovoltaic performance (i.e., photovoltaic parameters and resistances of electron recombination), indicating the practical feasibility of recycling car batteries for lead-based PSCs.—Chen et al.
PSC technology has advanced rapidly from initial experiments to a point where its efficiency is nearly competitive with that of other types of solar cells. The power conversion efficiencies reached over 15% within 18 months of development; perovskite-based photovoltaic cells have now achieved power-conversion efficiency of more than 16%—approaching that of many commercial silicon-based solar cells. Accordingly, interest in the technology in the research community has soared.
(C&EN quoted University of Oxford physicist Henry J. Snaith as saying “It seems we’ve all been bitten by the perovskite bug.”)
However, the researchers note, the manufacture of PSCs raises environmental concerns regarding the over-production of raw lead ore, which has harmful health and ecological effects. Using recycled lead from old car batteries can alter the environmental impact.
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 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 says.
Belcher says that currently, 90% 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.
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 says.
The work, which also included research scientist Jifa Qi, graduate student Matthew Klug and postdoc Xiangnan Dang, was supported by Italian energy company Eni through the MIT Energy Initiative.
Po-Yen Chen, Jifa Qi, Matthew T. Klug, Xiangnan Dang, Paula T. Hammond and Angela Belcher (2014) “Environmentally-responsible fabrication of efficient perovskite solar cells from recycled car batteries” Energy Environ. Sci., doi: 10.1039/C4EE00965G
Hui-Seon Kim, Sang Hyuk Im, and Nam-Gyu Park (2014) “Organolead Halide Perovskite: New Horizons in Solar Cell Research” The Journal of Physical Chemistry C 118 (11), 5615-5625 doi: 10.1021/jp409025w