Turning bricks into batteries
Red bricks are one of the world’s favourite building materials. Based on thousand year old technology, they’ve stood the test of time and barely changed. But now the humble house brick could be able to undergo a remarkable transformation - and turn into a battery! Research from Washington University, St Louis, and published in Nature Communications, has found a way to coat bricks with conductive polymers that link up with the red pigment inside the brick - which is iron oxide - and enable it to store electricity. Your home could potentially become its own power supply! Adam Murphy heard how they do it from the inventor Julio D’Arcy...
Julio - Bricks are actually porous. We could actually flow a gas inside those pores and that gas was able to react with a red pigment in the brick. We then were able to send a second gas inside the brick that transformed all the red pigment into a plastic that conducts electricity that is called PEDOT. This plastic is very special. It's not like the plastic bags that you buy at the supermarket. They actually have features at the nanoscale. So a brick once it's coated by our plastic, if you put it inside a microscope, it no longer looks like a brick. It actually is coated by all these little fibers that increase the surface area of the brick and are actually impregnated throughout all the pores. When you put all those things together, we were able to transform a brick into basically an electrode. And if you put two of them together, you build a battery or a supercapacitor.
Adam - And how do you get the power out again? Is it just a case of putting one electrode at one end of the brick and another electrode at the other end?
Julio - That's it! That's how you do it. Just like you would do with a battery. So the bricks themselves would have to have wires and the wires can be inside the walls and those wires would, you know, you would put a socket on the wall cause that's how we, that's how we connect our devices. Um, yeah, they would use cables. You would have cables that run to the solar cells that bring the electricity down to the bricks. And then the bricks themselves could be connected in series or parallel. But that unit of bricks would have two cables, a positive cable and a negative cable, that would allow an electrician to basically connect it to a socket. And then you can connect your electrical devices.
Adam - And would there be any danger say of someone leaning against this wall and zapping themselves?
Julio - That's a really good question. And so, yeah, the idea is that you do not want to touch the electrodes of a battery. You do not want to touch the electrodes of the wall. And that's okay. That's not a problem, because when you engineered these bricks into a device that stores energy, you don't have to put the coating facing towards the inside of the house. So most houses, there's always a gap in the walls. And in that gap that allows you to basically flip the bricks around and have the coating facing towards the inside of the wall. Our bricks are also coated by a protective layer of epoxy that we tested and is completely insulating. And it protects anyone that would touch the brick. The amount of energy that's stored is very little at this moment, but if we store more energy, yeah, we would continue to put protective layers on the surface of the bricks. Just like a battery when you buy it, it's inside a housing, a metal housing, or, you know, sometimes batteries come in a plastic housing. In this case, we're thinking a plastic housing would work as we demonstrated epoxy, five minute epoxy, works really good with our bricks, for protecting the brick from, uh, transmitting electricity, protecting the brick from being affected by water. Our work demonstrates that if you take our bricks and you coat them in an epoxy, you can actually submerge them in water and they continue to deliver energy because their entire system is just protected by the epoxy.