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ENERGY STORAGE Bricks turned into supercapacitors with a special coating

| Author / Editor: Luke James / Johanna Erbacher

Chemists in the United States have developed so-called ‘smart bricks’ that are able to store energy until it’s required to power devices. These open up a range of exciting potential applications, including energy storage integrated into building architecture.

The brick supercapacitor device developed by researchers in the U.S. is shown here powering a green light-emitting diode.
The brick supercapacitor device developed by researchers in the U.S. is shown here powering a green light-emitting diode.
(Source: D’Arcy laboratory, Department of Chemistry, Washington University in St. Louis)

The humble red brick, the type that has been used in architecture and construction for generations, has now been turned into a sort-of “battery” that is capable of storing electricity, a development that could see buildings turn into literal powerhouses. This is the latest in a series of works by research teams worldwide that are finding new and clever ways to integrate power storage and generation into the infrastructure of buildings.

In this study, the research team exploited the porous nature of red bricks by filling these pores with tiny nanofibers of a conducting plastic that’s capable of storing charge.

Bricks as supercapacitors

Technically, the power bricks are supercapacitors rather than batteries. Supercapacitors store electricity as a static charge in solids rather than through chemical reactions like in batteries. That’s a good thing, though, because supercapacitors charge and discharge much faster than batteries, which makes an innovation like the one described in this study particularly valuable for a wide range of applications.

However, supercapacitors have one main drawback—they’re only capable of storing a small fraction of energy. Researchers the world over are frantically working to increase the energy density of supercapacitors. Much of this stems from the pressing climate crisis and the need to find better ways to store renewable energy.

“A solar cell on the roof of your house has to store electricity somewhere and typically we use batteries,” said Julio D’Arcy, at Washington University in St Louis, US, who was part of the research team. “What we have done is provide a new ‘food-for-thought’ option, but we’re not there yet.”

A conductive polymer coating

In this study, the researchers have developed a coating of the conductive polymer PEDOT, or (poly3,4-ethylenedioxythiophene) which is made up of nanofibers that penetrate the brick’s inner porous network. A polymer coating remains trapped in a brick and serves as an ion sponge that is capable of conducting electricity.

Iron oxide, the pigment that gives bricks their distinctive red color, is essential for triggering the polymerization reaction. By their calculations, the researchers believe that a wall made from these supercapacitor bricks could “store a substantial amount of energy”.

“PEDOT-coated bricks are ideal building blocks that can provide power to emergency lighting,” D’Arcy said. “We envision that this could be a reality when you connect our bricks with solar cells – this could take 50 bricks in close proximity to the load. These 50 bricks would enable powering emergency lighting for five hours.

Furthermore, a supercapacitor brick wall could be recharged hundreds of thousands of times within an hour. Just two bricks would be enough to power microelectronics sensors, says the research team.

The first bricks produced by the research team can store enough energy to power a small light. If their capacity can be increased, however, they could become a low-cost alternative to lithium-ion batteries.

According to the research paper published in Nature Communications, five-minute epoxy creates a waterproof case that allows the bricks to operate while submerged in water. Furthermore, a gel electrolyte would extend cycling stability to around 10,000 cycles with capacitance retention of roughly 90 percent.

Dan Brett, Professor of Electrochemical Engineering, UCL, said: “The performance [of the bricks] is a long way short of bespoke supercapacitors but the principle is proven and there is significant scope for improving the storage characteristics by optimizing the structure and chemistry of the bricks.

This will be the research team’s next focus.

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