PEDOT coating turns bricks into supercapacitors

A conductive coating of PEDOT has been applied to samples of red bricks to convert them into a form of supercapacitor.

Red brick device developed by chemists at Washington University in St. Louis lights up a green light-emitting diode. The photo shows the core-shell architecture of a nanofibrillar PEDOT-coated brick electrode (Image: D'Arcy laboratory, Department of Chemistry, Washington University in St. Louis)

Chemists in the School of Arts & Sciences at Washington University in St. Louis have developed the so-called ‘smart bricks’ that can store energy until required for powering devices. A proof-of-concept published in Nature Communications shows a brick powering a green LED light.

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"Our method works with regular brick or recycled bricks, and we can make our own bricks as well," said Julio D'Arcy, assistant professor of chemistry. "As a matter of fact, the work that we have published in Nature Communications stems from bricks that we bought at Home Depot right here in Brentwood [Missouri]; each brick was 65 cents."

D'Arcy and colleagues, including Washington University graduate student Hongmin Wang, first author of the new study, showed how to convert red bricks into a type of supercapacitor.

"In this work, we have developed a coating of the conducting polymer PEDOT [poly(3,4-ethylenedioxythiophene], which is comprised of nanofibres that penetrate the inner porous network of a brick; a polymer coating remains trapped in a brick and serves as an ion sponge that stores and conducts electricity," D'Arcy said in a statement.

The red pigment in bricks - iron oxide - is essential for triggering the polymerisation reaction. The authors' calculations suggest that walls made of these energy-storing 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.

"Advantageously, a brick wall serving as a supercapacitor can be recharged hundreds of thousands of times within an hour. If you connect a couple of bricks, microelectronics sensors would be easily powered."

According to the paper, five-minute epoxy serves as a waterproof case that allows the supercapacitor bricks to operate while submerged underwater. Furthermore, a gel electrolyte extends cycling stability to 10,000 cycles with around 90 per cent capacitance retention.

Commenting on the study, Dan Brett, Professor of Electrochemical Engineering, UCL, said: “Heat has been the overriding area of interest when considering energy storage integration within the fabric of buildings. This study shows that there is potential to store electrical energy as well. The performance is a long way short of bespoke supercapacitors but the principle is proven and there is significant scope for improving the storage characteristics by optimising the structure and chemistry of the bricks.

“From a materials science perspective the work is intriguing and report some interesting features of this particular form of super capacitor,” added Richard McMahon, Professor of Power Electronics, University of Warwick.  “On the other hand, I think it's fair to say that although this work is an interesting demonstration of a possibility it is a long way from practical application.”