Physics made aqueous suspension of hydrophobic activated the recovered graphene oxide with additives for easy and safe production technology of ultracapacitors. They added into water, colloidal silica, graphene oxide and carbon nanotubes. Capacity flexible capacitors. obtained from aqueous suspensions was 180 Farad per gram. Article published in The Journal of Physical Chemistry Letters.
Ultracapacitors or supercapacitors — devices for storing energy with high capacity, which serves classic plates of the electric double layer between the electrode and the electrolyte. They begin to apply in many fields of technology, which requires the accumulation and release of large amounts of electricity for a short time, for example, defibrillators or the flashes of cameras.
Graphene has high conductivity and high surface area of 2630 square meters per gram and is considered a promising material for supercapacitors. Scientists are trying to deal with a decrease in surface area during production of the supercapacitor, but the application of the electrode is very dependent on how perenosyatsya individual sheets of graphene from the precursor resulting in porous structure. Use of activated recovered graphene oxide with a rigid three-dimensional structure partly solves this problem. Engineers tried to improve the quality of the electrodes, by varying the ratio of initial components and the distribution of the pore sizes. However, all these works require complex multi-stage processing with the use of toxic solvents, making it difficult to scale for industrial production.
Skrepnick Basil (Vasyl Skrypnychuk) with colleagues from the University of Umea found a simple method of obtaining an aqueous suspension of activated carbon recovered graphene oxide at different concentrations and measured the electrical characteristics of the electrodes of the supercapacitor made from this material. The resulting slurry suitable for most industrial methods for the manufacture of electrodes — coating, applying with a brush and blade. Flexible electrodes are obtained by simple drying of the suspension, have a high surface area (more than 1800 square meters per gram) and a good 800 conductivity in Siemens per meter.
In order to suspendirovanie hydrophobic graphene materials, physics tried as additives common viscosity modifiers — a colloidal oxide of silicon and karboksimetilirovaniya pulp, adding which the gel-like suspension with insufficient adhesion to the substrate. For a more durable contact of the liquid with the surface, they added carbon nanotubes due to their high electrical conductivity, as polymers are common adhesive agents are mostly insulators and are not suitable for use in electrodes. To improve the contact between the hydrophobic and hydrophilic phases of a suspension, the scientists have made graphene oxide, which has areas of both types.