'Metal-Air Scavenger' to Power Electronics, Robots, and Vehicles
Researchers from Penn Engineering introduce their "metal-air scavenger" vehicle, which gets energy not from a battery, but from breaking chemical bonds in the aluminum surface it travels over. The technology works like both a battery and an energy harvester; the result is a power source that has ten times more power density than the best energy harvesters and 13 times more energy density than lithium-ion batteries. Like a traditional battery, the metal-air scavenger starts with a cathode that’s wired to the device it’s powering. Underneath the cathode is a slab of hydrogel, a spongy network of polymer chains that conducts electrons between the metal surface and the cathode via the water molecules it carries. With the hydrogel acting as an electrolyte, any metal surface it touches functions as the anode of a battery, allowing electrons to flow to the cathode and power the connected device. For this study, the Penn Engineering researchers connected a small motorized vehicle to the device. They say that in the future, robots could keep themselves powered by seeking out and “eating” metal, breaking down its chemical bonds for energy like people do with food.
Transcript
00:00:00 Large amounts of untapped power are contained in the metal all around us. Researchers at Penn have developed a prototype that extracts energy from metal surfaces to power portable electronics. What we've developed is a metal scavenging technology. Instead of storing the energy within the device, kind of like your electric vehicle stores it in a battery. The problem is that those batteries are constrained in how much energy they can store. So what if you say, "Let's not store the energy within the system. Is there a way we can get energy from the environment around us?" We want to utilize the waste of metal in our surroundings and we want to decrease the weight
00:00:41 we have to transport for our electronic devices. So what we've developed is a technology that allows us to extract that energy from metals without causing that much degradation to the metals, and being able to do that also in a highly efficient manner. This is because of the strong bonds in metal, which has about three times more energy density than the best commercial lithium ion batteries. We've developed a prototype of our metal harvester. What it looks like is basically a thin film of cloth that you just place onto a metal surface and can basically extract energy from that metal. We've attached it to a little toy vehicle.
00:01:14 So you have the metal surface, on top of the metal surface is a material that's kind of like Jello. It's called a hydrogel and it stores salty water in this particular case. It is also, on top of that, connected to a piece of carbon cloth that has little tiny beads of platinum on it, the catalyst basically for the reduction of oxygen in the air. The ions pass in between these layers and then the electrons move because they can't go through the electrolyte. They move and they go through and they power the external device, in this case it's the robotic vehicle. I think it's easy to commercialize.
00:01:44 You can imagine a band-aid harvester. You just remove the case, and paste onto a metal surface to charge you phone or any other devices. There's a lot of uses where you might want to put sensors onto metal surfaces. One to sense the quality of the air in the environment, or how many cars go by to monitor traffic. In all these cases, you want just a little tiny electronic device that can be placed in a key position and also operate for a long period of time. We like inventing new technologies and enabling new capabilities but ultimately one of the biggest things we're interested in is making a real impact in the world.