Usually, the phrase “power brick” lovingly refers to the AC adapter for something like a laptop. But what if that term was quite literally, including an actual brick?
A team led by Hongmin Wang at the University of Washington set out to make a real energy brick. More specifically, they wanted to see if they could use a steam coating technique to turn ordinary red bricks into a piece of a supercapacitor. In fact it is not so all as strange as it sounds, given that the red of a brick is an iron ore, and iron is a common ingredient in some battery chemicals. Bricks are often porous, which means that there is a lot of surface where a thin layer can interact with that iron.
The process (something they had developed before) involves heating the bricks in a closure along with hydrochloric acid and an organic compound that cuts mercilessly into “EDOT”;. The two liquid substances evaporate and condense on the interrupted surface of the brick. The acid dissolves some of the iron’s minerals, releasing iron atoms that help organic molecules bond to form polymer chains (graduating in “PEDOT”) that coat the surface. The polymer makes microscopic, tangled fibers that form a continuous, electrically conductive layer on each side of the brick, which otherwise remains. (This has the effect of turning black bricks, though.)
The team tested the performance in several configurations, including one with a strong electrolyte sandwich gel between the bricks like mortar. Coating the entire item in epoxy makes it waterproof (as in, “works under water” waterproof) and also prevents the electrolyte from drying out all the time. Many combinations of bricks bonded in series and in parallel are obviously possible, although for testing they connected three small cubic-sized brick units in series. After fully charging in 15 seconds, this configuration enabled an LED for about 11 minutes before the voltage dropped from the initial 2.7 volts to below the required 2.5 volts of LED.
Even with full-size bricks, the total energy conservation is. Less than large. They estimate that a wall of these bricks can hold about 1.6 watts-hours per square meter of wall surface. This means that a three-foot by six-meter wall (10 feet by 20 meters) can hold about 20 watts-hours of electricity. As a result, researchers’ steps toward this idea are less dramatic than “turning your home into a battery!”
“Our supercapacitor technology adds value to a ‘cheap’ building material and demonstrates a scalable process that allows energy conservation to empower microdevices embedded in architectural applications that use firebricks,” they write. These powered walls will probably not be challenging Tesla Powerwall (13.5 weighthours-watts to less than one square meter on the wall) any time soon. But it is a creative concept – an overlapping brick would not be just another brick in the wall.
Nature Communications, 2020. DOI: 10.1038 / s41467-020-17708-1 (About DOI).