Buildings as Power Banks? MIT’s Concrete Battery Stores Tenfold Energy
- Ritambhara K
- Oct 3
- 3 min read
Concrete has long been the backbone of our cities, but a new breakthrough suggests it could also power them. Researchers at MIT have developed an improved version of a carbon-cement supercapacitor, a material that allows ordinary concrete structures to store and release electricity. The advance brings us closer to a future where sidewalks, bridges, and even homes double as massive energy storage systems.
From Building Material to Battery
The technology, called electron-conducting carbon concrete (ec³, pronounced e-c-cubed), is created by mixing cement, water, ultra-fine carbon black, and electrolytes. This recipe produces a nanoscale conductive network inside the concrete, effectively turning the material into a giant supercapacitor. Unlike batteries, which rely on chemical reactions, supercapacitors store energy physically, making them more durable and faster to charge.
The latest research, published in PNAS, shows that MIT’s optimized manufacturing methods and carefully chosen electrolytes have boosted the energy capacity of ec³ by a factor of ten. Just last year, powering an average home required 45 cubic meters of ec³ — the amount of concrete in a basement. Now, only 5 cubic meters — roughly the size of a single basement wall — could do the same job.
Cracking the Code of the “Nanonetwork”
To understand why the material performed better, the team used advanced imaging techniques, including FIB-SEM tomography, which slices away layers of material and reconstructs them in 3D at high resolution. They discovered that the carbon black forms a fractal-like web around tiny pores, allowing electrolytes to infiltrate and current to flow smoothly. This deeper knowledge helped guide the design of higher-performance mixtures.
“Understanding how these materials assemble at the nanoscale is key to unlocking new functions,” said Admir Masic, co-director of MIT’s EC³ Hub and associate professor of civil and environmental engineering.
Smarter Mixing, Stronger Performance
Armed with this knowledge, researchers tried different electrolytes and concentrations. Remarkably, they found that even seawater could work, opening doors for marine applications like supporting offshore wind farms.
The team also streamlined the process. Instead of curing the concrete first and soaking it in electrolytes, they added the electrolytes directly during mixing. This method allowed thicker electrodes to form, which stored more energy.
The best results came from organic electrolytes combining quaternary ammonium salts — common in household disinfectants — with acetonitrile, a highly conductive industrial liquid. A cubic meter of this enhanced ec³ — about the size of a refrigerator — can now store over 2 kilowatt-hours of electricity, enough to power an actual refrigerator for a day.
Lessons from the Romans, Applications for the Future
While ec³ doesn’t yet match the energy density of conventional batteries, its strength lies in being part of the structures we already build. Walls, slabs, and roads could quietly store power for decades, matching the lifespan of the concrete itself.
The team even drew inspiration from ancient Rome. Just as the Pantheon has endured for centuries, MIT researchers envision future buildings where material science and architecture merge. To demonstrate the idea, they constructed a small ec³ arch that both supported weight and powered an LED. Intriguingly, the light flickered when more stress was applied, hinting at a built-in self-monitoring capability that could one day help structures sense their own health.
Scaling Up to Real-World Use
The technology is already being piloted. In Japan, ec³’s thermal conductivity has been tested for heating sidewalks as an alternative to salt in icy conditions. Looking ahead, the team imagines parking lots and roads that recharge electric vehicles, or homes capable of running entirely off the grid.
“What excites us most is that we’ve taken a material as ancient as concrete and shown that it can do something entirely new,” said James Weaver, co-author and associate professor at Cornell. “By combining modern nanoscience with an age-old building block of civilization, we’re opening a door to infrastructure that doesn’t just support our lives — it powers them.”
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