Whoa: Scientists Turned Red Bricks Into Supercapacitors
Coating red bricks with conductive polymers turns them into supercapacitors.
The resulting treated walls could act as a low-cost version of something like the Powerwall.
Red bricks contain conductive hematite and are full of micropores, making them ideal interfaces.
In new research, scientists say they can turn bricks into smart bricks that hold electricity. By coating bricks with a polymer containing intrusive nanofibers, they’ve turned normal red bricks into something that can conduct and store electrical current.
The polymer, poly(3,4-ethylenedioxythiophene) or PEDOT, is critical to this research—but so is simple red clay.
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Let’s look at how this setup works. First is the brick itself, which is made of clay that’s red because of an age-old pigment named hematite. The researchers explain:
“The red color of a brick originates from hematite, a pigment first utilized by humans 73,000 years ago and serving today as a low-cost naturally abundant inorganic precursor for catalysts, magnets, and alloys. State-of-the-art energy storage materials are also produced from hematite.”
When hematite-inflected red clay is fired into bricks, it becomes uniquely fixed and microporous, which allows the nanofibers in PEDOT to snake right in. This is done through a carefully controlled chemical reaction.
“Deposition of PEDOT nanofibers is initiated by dissolving α-Fe2O3 at 160 °C with HCl vapor,” the scientists explain, describing a process called oxidative radical polymerization. To make the right nanofibers with the right properties, the acidity and everything else must be closely monitored.
In a press release, the scientists described the resulting polymer-bonded brick surface as an “ion sponge” that acts as a supercapacitor—a device capable of conducting and storing quite a bit of electrical energy. Supercapacitors are related to (but not the same as) batteries, and having a diverse field of options of all kinds gives scientists new ways to try to maximize energy efficiency.
“Notably, a brick wall constructed using our nanofibrillar PEDOT-coated bricks holds the potential to deliver a maximum device capacitance of 11.5 kF m⁻² and an energy density of 1.61 Wh m⁻²,” the researchers explain. That’s 1.61 Wh per square decimeter of area, so 161 Wh per square meter for a wall made of regular bricks treated with polymer.
Let’s quickly compare that as best we can to Elon Musk’s Tesla Powerwall, an existing consumer solution for energy storage. It’s not a true wall, but a flat-ish appliance that you can mount to the wall if you want. It weighs 250 pounds, is nearly 6 inches thick, and costs about $10,000 with installation. The surface area of one side is less than one square meter, and the Powerwall stores 13 KWh of energy—1,300 Wh, so just over eight times more.
If you’re thinking that’s not a fair comparison, it’s not exactly supposed to be. The Powerwall is a luxury product at this point, despite Musk’s efforts to work with tax credits and other incentives for private citizens. It’s a great product, but there’s a huge space in the market for something that does less and also costs a lot less.
“Our supercapacitor technology adds value to a ‘dirt-cheap’ construction material,” the researchers conclude.
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