Scientists create paper-like eco-friendly flexible batteries
Almost all portable electronics are powered by rechargeable batteries or batteries, which “eat off” a substantial part of the usable volume and make the device heavier. Fuel cells and solar panels, considered as options for solving this problem, have not yet reached the stage when they could become real competition for traditional power sources. According to the researchers, carbon nanotubes, ultimately, can become the basis of compact and flexible batteries and “supercapacitors” (power supplies that can give off energy in one powerful pulse).
One of the obstacles standing in the way of creating flexible batteries is the need to form a layered structure. In a first approximation, the power supply consists of layers of electrodes; charge retaining layers; and an insulator layer between them. This structure is difficult to maintain flexibility.
However, scientists at the Rensselaer Polytechnic Institute and MIT have succeeded in creating a new material that eliminates the need for a multilayer structure. They “grew” carbon nanotubes and filled the cavities between them with cellulose – the material of which, to a large extent, paper is made. A large amount of cellulose – about 90% – gives the material a paper-like appearance, and its black color is due to the presence of carbon nanotubes.
By folding two sheets of “paper” and saturating them with electrolyte, scientists received a unique power source. Since the electrolyte does not contain water, the source remains operational over a wide temperature range. It can simultaneously be a battery and a “supercapacitor” – usually these are two fundamentally different products. The power supply can be rolled up, folded and cut into arbitrary pieces without loss of performance. “Paper batteries”, like ordinary ones, can be connected, increasing their power. Because the sheets are very flexible, they can be shaped into complex shapes and filled into void spaces in a portable electronic device. The low weight of the battery is said to make it a good candidate for vehicle use.
Since there are no toxic substances in the power source, it can be used in implants. In addition, the battery is biodegradable, making it an environmentally friendly product.
Even at the prototype stage, the development turned out to be quite workable – the energy of the “sheet of paper” is enough to power a small fan.
As for the technical process for the release of “paper batteries”, according to scientists, it may be similar to the process used in printing presses – relatively speaking, the batteries will be released in rolls.
The terms of commercialization of the development have not been named, while it is a question of finding ways to increase energy intensity and developing a technology for mass production. Patent pending.
Source: Rensselaer Polytechnic Institute