Concrete has long been the backbone of civilization, shaping everything from roads and bridges to the homes we live in. Now, thanks to breakthroughs at MIT, it could soon serve a second role as a massive, built-in energy storage system. A new kind of electron-conducting carbon concrete (ec³) is showing remarkable potential to function as both structural material and giant “battery”.
Developed from a blend of cement, water, ultra-fine carbon black, and electrolytes, ec³ creates a conductive “nanonetwork” that acts like the wiring inside a supercapacitor. According to MIT researchers, recent advances in manufacturing and electrolyte optimization have increased its energy storage capacity tenfold.
Back in 2023, powering an average home for a day required about 45 cubic meters of ec³ — roughly the volume of a basement. Today, the same can be achieved with only 5 cubic meters, comparable to the size of a basement wall.
“This is about the sustainability of concrete,” explains Admir Masic, co-director of MIT’s EC³ Hub and associate professor of civil and environmental engineering. “Concrete is already the world’s most-used construction material, so why not take advantage of that scale to create other benefits?”
The leap in performance came after researchers mapped ec³’s internal structure using FIB-SEM tomography, a process that slices and images the material at nanometer resolution. They discovered a fractal-like web of carbon black surrounding tiny pores, creating pathways for electrolytes to penetrate and current to flow.
“Understanding how these materials ‘assemble’ themselves at the nanoscale is key to achieving these new functionalities,” adds Masic.
Armed with this knowledge, the team tested different electrolytes, including seawater, which could make ec³ especially useful for coastal or offshore wind applications. They also improved efficiency by mixing electrolytes directly into the concrete rather than soaking it afterward, enabling thicker electrodes with higher capacity.
The best results came from using organic electrolytes combining quaternary ammonium salts (common in disinfectants) with acetonitrile, a conductive industrial liquid. Just one cubic meter of this ec³ mix about the size of a refrigerator can store over 2 kilowatt-hours, enough to run a refrigerator for a day.
To prove the concept, the team built a miniature ec³ arch. Not only did it support weight, but it also powered an LED light at 9 volts. When stressed, the arch’s light flickered, hinting at a built-in self-monitoring ability to detect structural stress.
Masic drew parallels to ancient construction: “The Ancient Romans made great advances in concrete construction. If we keep up their spirit of combining material science with architectural vision, we could be at the brink of a new architectural revolution with multifunctional concretes like ec³.”
Already, ec³’s thermal conductivity has been put to use heating sidewalks in Sapporo, Japan, a salt-free method of snow control. Future applications could include roads and parking lots that charge EVs, or off-grid homes storing their own solar power.
“The answer is that you need a way to store and release energy,” says Franz-Josef Ulm, EC³ Hub co-director. “This has usually meant a battery, which often relies on scarce or harmful materials. We believe ec³ is a viable substitute, letting our buildings and infrastructure meet our energy storage needs.”
For James Weaver, co-author and associate professor at Cornell University, the breakthrough is a bridge between ancient and modern: “By combining modern nanoscience with an ancient building block of civilization, we’re opening a door to infrastructure that doesn’t just support our lives, it powers them.”