By using nanotechnology, an American research team has transformed modest home building bricks into a battery that can store electricity, increasing the likelihood that buildings will one day become actual power stations.

"The new technology exploits the porous nature of burnt red bricks by filling the pores with microscopic nanofibers of electrically conductive plastic that can store charges," said environmental editor Damian Carrington in an article for The Guardian.

Super capacitors

The "battery" brick stores enough electricity to power the small lights, but if its capacity can be increased, it could become a low-cost alternative to the lithium-ion batteries currently in use.

Strictly speaking, energy bricks are super capacitors, not batteries. They store electricity as a constant charge in solids, not through chemical reactions as in batteries.

As Carrington says, "The advantage of supercapacitors is that they charge and discharge much faster than batteries, but so far they can only conserve a fraction of the energy."

"Another advantage of supercapacitors is that they can be charged and recharged many times more than batteries before losing their ability to store electricity. Energy bricks can be recycled 10,000 times before their capacity drops dramatically."

And researchers around the world are working to increase the capacity of supercapacitors, as well as the speed of charging batteries. Finding better ways to store electricity is an important part of combating the climate crisis, as it will allow abundant but intermittent renewable energy to be stored until needed.

The advantage of super capacitors is that charging and discharging them is much faster than batteries, but they only conserve a small fraction of the power (Wikipedia)

Still to upgrade

"The solar cell on the roof of your house stores electricity somewhere, and we usually use batteries for that," said Julio D'Arcy of Washington University in St Luis in the United States who was part of the research team. "What we have done is present a new option ... but we have not yet reached it."

The energy density in the first energy bricks, reported in Nature Communications, is only 1% of that of lithium-ion batteries.

Darsi believes this could be increased tenfold by adding materials such as metal oxides to store more charge in the bricks, which would make energy bricks a commercial alternative.

But the hope is ultimately to match the energy density of lithium-ion batteries, Darcy says, "If that is the case, this technology is much cheaper than lithium-ion batteries."

"Heat has been the overriding area of ​​concern when looking at energy storage within the fabric of buildings," says Dan Brett, professor of electrochemical engineering at University Collage London, UK.

"This study shows that there is potential for electrical energy storage as well. The performance is very far from dedicated supercapacitors, but the principle is proven and there is much room for improvement," Brett adds.

The energy density of the first energy brick is only 1% that of lithium-ion batteries and can be increased up to 10 times (Wikipedia)

Small prototypes

The researchers created small prototypes of the energy bricks by using chemical fumes to react with the red iron oxides in the bricks and then to form a network of plastic nanofibers.

A special plastic material called Pedot was used, because it is a very good conductor of electricity, and the reaction turned the red bricks into a dark blue color.

Darcy says that the reactions used to create energy bricks may have little effect on their structural properties, but in any case the bricks are today commonly used in homes as decorative facades.

Richard McMahon, professor of power electronics at the University of Warwick in the United Kingdom, said that the research was interesting, as "energy storage is of great importance in the modern era, especially in the electrical form."

In contrast, McMahon argues that "although this work is an interesting demonstration of potential latent, it is still very far from practical application."