The cement devices are a kind of simplified battery called supercapacitors.
Yeah, cement as a supercap is a terrible idea on every conceivable level. First off, cement CO2 emissions are astounding. Second, what happens when this porous material gets wet and a short to ground happens? Your cement pad suddenly vaporizes you if you turn on the sink.
If carbon black cement was used to make a 45-cubic-meter volume of concrete—roughly the amount used in the foundation of a standard home—it could store 10 kilowatt-hours of energy
So, 65 metric tons of cement to store the energy equivalent of less than 700 cylindrical cells, or two Tesla modules from an old Model S. This is purely idiotic. Oh, and it's never serviceable or upgradeable without tearing up and relaying all that concrete. A battery pack you could hide in your closet is capable of vastly outpowering this 45 cubic meter pipe dream.
It's too bad "science" doesn't filter out obvious junk, because it would be a much better site.
Doesn't seem completely impossible with the estimated storage capacity, but like with all of these things, drastically changing the build up of concrete means changing the properties of the very thing used to hold your home together.
It might be cheap materials, but the effort involved also seem very high having to cut up after the hardening to create the super capacitors. Which again may affect structural integrity.
The "could" in the headline is extremely speculative. It says in the article they managed to power a few LED lights using a small slice of electrified cement.