Building Battery? Scientists Find Way to Store Electrical Charge in Cement

Scientists at the Massachusetts Institute of Technology (MIT) say they have found a new way to turn ancient materials into a capacitor for storing electricity.

In a research paper published in the Proceedings of the National Academy of Sciences (PNAS), a group of MIT scientists described how they took cement, water, and carbon black (a type of powdery charcoal), and by mixing them together, accidentally created a new type of battery.

"The material is fascinating, because you have the most-used human made material in the world, cement, that is combined with carbon black, that is a well-known historical material – the Dead Sea Scrolls were written with it," Admir Masic, a materials scientist at MIT, said in a news release.

"You have these at least two-millennia-old materials that when you combine them in a specific manner you come up with a conductive nanocomposite, and that's when things get really interesting."

When the materials are mixed together, the carbon black forms ribbons throughout the mixture, and as the water is absorbed by the cement, it leaves voids. The lengthy surfaces with a gap between them are then able to act as capacitor plates, storing a charge in the voltage difference in the same way that a battery does.

According to the scientists, if it were incorporated into a house’s foundation, it could potentially store a day’s worth of energy without sacrificing the building’s structural strength. They also envision a concrete roadway using the material that might be able to charge electric cars as they drive on it.

"These properties point to the opportunity for employing these structural concrete-like supercapacitors for bulk energy storage in both residential and industrial applications ranging from energy autarkic shelters and self-charging roads for electric vehicles, to intermittent energy storage for wind turbines," the scientists noted in their paper.

With the rush to convert gasoline-powered cars to all-electric, demand for the rare metallic components of powerful batteries, such as lithium and cobalt, has soared. Prices have spiked, new mines and production facilities are lucrative business opportunities, and the complex of politics of pollution caused by the mining and refining processes have also come to the fore. The ability to build a battery out of ordinary materials could be extremely valuable.

The MIT brains' discovery brings to mind a much-hyped proposal in recent years to construct solar-powered roadways, converting a huge mass of sun-soaking asphalt surfaces across the country into a network of solar energy generation. The ambitious proposal went viral on the internet in 2014, but an attempt to prove the practicality of the technology in a section of roadway instead wound up exposing its deep faults. It turned out to be prohibitively expensive to build, vulnerable to quick wear and even catching on fire, and wasn’t very good at capturing sunlight on top of it all.