The researchers are coating the fibers in paper and textiles with nano-scale conductive materials to turn low-cost materials into high-performance supercapacitors for the electric grid, which could be a transformative and environmentally friendly energy storage technology. The rough surfaces of paper and textiles are ideal for energy devices in which large surface roughness is preferred, such as supercapacitors and lithium ion batteries. For supercapacitors, the surface roughness of the electrode, or current collector, is beneficial for manipulation of electrons and ions. For grid-scale storage, which will be essential for high penetration of wind and solar generation, supercapacitors seem to be a very attractive alternative to batteries due to much higher power density, faster charging and discharging, far superior cycle lifetime and greater reliability. However, low-cost, high-performance materials for grid-scale application are still in development.
The investigators have made exciting progress in the past two years, as reported to date in four scientific publications. First, they have demonstrated that graphene, which is a one-atom-thick highly conductive sheet of bonded carbon, combined with manganese dioxide and a conducting polymer can be applied to a textile substrate to produce a high capacity and high power supercapacitor. Secondly, they have shown that excellent supercapacitors can be fabricated by directly drawing graphite using a pencil, though in a precise pattern, on paper. The shear peeling of graphites produces multi-layer graphenes with a high proportion of conductive edge structures. These supercapacitors show stable long cycling performance and an areal capacitance much higher than previously reported. The paper supercapacitors demonstrated here can potentially lead to the development of all-paper electronics that are low cost and highly versatile.