Paper-thin, flexible and biodegradable battery being developed
We all know that the bulk of the weight of a gadget is thanks to its battery. Fuel cells and solar power, we have tried them all but the battery weight-to-capacity problem is still unresolved. There is hope however, because a new research suggests that carbon nanotubes may eventually provide the best hope of implementing the flexible batteries and supercapacitors needed to make our gadgets lighter. The major problem with designing flexible batteries and supercapacitors has always been the necessity of layering such devices. Usually, two electrode layers sandwich two charge-holding layers, with an insulating layer in the middle of it all. As the layers build up, flexibility goes down. To solve this problem the researchers from Rensselaer Polytechnic Institute and MIT have developed a new material that eliminates the need for a multilayer battery. This is what they did: “They grew carbon nanotubes on a silicon substrate and impregnated the gaps between the tubes with cellulose (plain old paper). The cellulose also covered the ends of the nanotubes, but once it had dried, the paper material could be peeled off of the silicon substrate, leaving one end of the carbon nanotubes exposed to form an electrode.”
The researchers further explain “Thus by putting two sheets of paper together with the cellulose side facing inwards (and a drop of electrolyte on the paper), a supercapacitor is formed. These supercapacitors retain the flexibility of normal paper, but they have a rating that is comparable to that of standard commercial hardware—a 100g sheet could replace a 1300mAh battery.” Since the medium is flexible one will be able to shape batteries of all sizes for very specific use. The researchers have also developed this: “By putting a drop of electrolyte on a single sheet and then putting a metal foil consisting of lithium and aluminum on each side, a lithium ion battery is formed. This paper device had a respectable 110mAh/g capacity.” The good thing about this research is that one day we could be looking at devices that are not only light in weight but also have the capacity to last long.