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Aug 11, 2023

MIT Cracks The Concrete Capacitor

It’s a story we’ve heard so many times over the years: breathless reporting of a new scientific breakthrough that will deliver limitless power, energy storage, or whichever other of humanity’s

It’s a story we’ve heard so many times over the years: breathless reporting of a new scientific breakthrough that will deliver limitless power, energy storage, or whichever other of humanity’s problems needs solving today. Sadly, they so often fail to make the jump into our daily lives because the reporting glosses over some exotic material that costs a fortune or because there’s a huge issue elsewhere in their makeup. There’s a story from MIT that might just be the real thing, though, as a team from that university claim to have made a viable supercapacitor from materials as simple as cement, carbon black, and a salt solution.

Supercapacitors use plate materials with a huge surface area on which to store charge. Conventional supercapacitors often use an electrochemical construction, and activated charcoal is a frequent electrode material. The cement capacitor uses the property of cement curing, which creates a dense branching network of openings in the material as the water reacts with the cement. By introducing electrically conductive carbon black to the mix and using potassium chloride solution instead of water, they turn the huge surface area of the resulting structure into a conductive electrode suffused with charged ions. This can be used as a plate of a supercapacitor, separated from another similar one by a membrane.

The suggestion is that, in the future, the foundation of a house or other structure might be cast in this cement to provide in-situ energy storage for rooftop solar generation. There’s an environmental question over the carbon footprint of cement manufacturing. Still, since the materials and techniques appear neither exotic nor expensive, we hope this is the one energy storage miracle discovery that makes it.

We’ve gone into more detail on supercaps in the past.

Header image: Michael Coghlan, CC BY-SA 2.0.