Concrete batteries that can be recharged could enable buildings to also store energy

The boring concrete buildings that can be seen in almost every city across the globe are the opposite of sustainability. The concrete industry emits a lot of carbon, accounting for up to 9% of all human-made carbon that gets into the atmosphere.

A recent innovation from Chalmers University in Sweden could alleviate this environmental burden. Civil engineers at the university have discovered a way to incorporate electrically conductive fibers into a cement-based mixture, allowing concrete slabs to function as batteries. This could lead to buildings that not only provide shelter but also power our needs.

Electrically charged concrete

Dr. Emma Zhang and Professor Luping Tang developed this rechargeable battery made of cement by modifying the usual concrete combination. They added short carbon fibers to improve conductivity and toughness, as well as a metal-coated carbon fiber mesh with iron and nickel serving as the anode and cathode, respectively.

While previous attempts have been made to create concrete batteries, this new design represents a significant improvement in terms of the energy density it offers. The new design's performance is at least ten times better than previous demonstrations and it is also rechargeable.

“The specific idea that we have developed — which is also rechargeable — has never been explored before. Now we have successfully tested the concept on a small scale,” Dr. Zhang stated in a press release.

The concrete batteries were put to the test in the lab — and they proved to be effective. However, the energy density is not very impressive at the moment, currently standing at just 7 watthours per square meter or 0.8 watthours per liter. To put this into perspective, the energy density of lithium-ion batteries that power smartphones and electric vehicles ranges between 250 Wh/L and 700 Wh/L.

Even though the energy density is significantly lower than commercial alternatives, there is still value here. Due to the large volume of concrete in new buildings that might incorporate this design, significant amounts of energy could theoretically be stored.

Expanding beyond the basic structure

The potential uses include powering LEDs, providing 4G connections in remote locations, and safeguarding concrete infrastructure from corrosion.

“It could also be combined with solar cell panels, for instance, to supply electricity and serve as the energy source for monitoring systems in highways or bridges, where sensors powered by a concrete battery could detect cracking or corrosion,” Zhang suggested.

Nevertheless, this concept comes with its own set of challenges. Extending the battery's lifespan to match that of concrete structures, which can last up to a century, and developing effective recycling techniques are crucial hurdles to overcome. Despite these challenges, integrating energy storage capabilities into the world's most commonly used building material could significantly influence our approach to energy crises. It could transform every concrete surface into a potential power source.

“We believe this idea will greatly help future construction materials to have extra functions like renewable energy sources,” concludes Tang.

Elsewhere, MIT engineers have combined cement, carbon black, and water to create supercapacitors (another type of battery) for storing energy in the base of buildings.

The results were published in the journal Buildings.