Electrochemical properties of carbon materials with high nitrogen content

The development and improvement of materials for storing electrical energy is important for the development of renewable energy technology. Some of the most suitable devices for storing electrical energy are supercapacitors, since they are able to withstand high charge and discharge currents, and they have a large number of recharge cycles. The characteristics of double-layer supercapacitors (DLSC) largely depend on the materials of the electrode on which the electrical double layer is formed. The most promising materials for the production of DLSC are carbon-based materials, such as activated carbons, soot, fullerenes, nanotubes, and graphene. It is possible to improve the characteristics of existing materials by increasing their electric conductivity, electrolyte wettability, and increasing the specific surface area. Doping carbon materials with nitrogen atoms makes it possible to solve these problems in many ways, including reducing their electric resistance. One of the ways to obtain nitrogen-rich carbon materials is the slow thermolysis of a mixture of coal tar pitch and melamine. This method makes it possible to obtain single-phase carbon materials with the pitch mass fraction up to 22 wt %. Electron microscopy methods have shown that with increasing nitrogen concentration, materials become loosened. With the use of X-ray phase analysis it has been shown that the resulting materials have a layered structure similar to graphite. Using the XPS method, it has been established that nitrogen atoms are embedded in the structure of the graphite sheet. The resulting materials are dominated by nitrogen atoms in the pyridine configuration. The electrochemical properties of the resulting materials have been studied in an electrochemical cell, which is a prototype of DLSC. The material with the nitrogen concentration of 4.2 wt % has the greatest capacity. The characteristics of the resulting DLSC have been compared with a commercially produced capacitor with a capacity of 220 mF and have shown their great similarity.