Havrykov D. Symmetric supercapacitors based on nanoporous carbon materials with optimized electrode structure

The dissertation is devoted to the creation of symmetric supercapacitors with improved specific parameters and the creation of hybrid power supplies on their base. The dissertation investigates the influence of the porous structure and particle size distribution of carbon materials on the capacity and power of supercapacitors. The optimal thickness of the energy accumulating component of the electrodes is determined for supercapacitors with high specific energy density and for supercapacitors with high power. Parasitic processes that negatively affect the service life of hybrid power supplies are also studied, and external electronic devices that neutralize the influence of parasitic processes are proposed. Influence of the nanoporous structure of carbon materials on the specific parameters of supercapacitors was investigated in the dissertation. It has been shown that carbon materials by nanoporous structure should be divided into two categories. The first category includes materials that provide high specific energy consumption, and the second - materials that provide high specific power of supercapacitors. It has been experimentally established that for electrolytes based on a solution of tetraethylammonium tetrafluoroborate in acetonitrile, the pore size in the carbon materials that provide the maximum specific energy is in the range from 1 to 3 nm and materials in which the pore size is 2,5 nm provides high specific power parameters. A theoretical model is proposed that explains the nonlinear dependence of the internal resistance of a supercapacitor on the thickness of the energy-accumulating component of its electrodes. The results of theoretical calculations correlate well with experimental data. The operation of a hybrid power supply based on a block of supercapacitors and a battery has been investigated. It is proved that for stable operation of the hybrid power supply it is necessary to use additional electronic devices: a device that limits the maximum discharge current of the battery, a device that limits the maximum charge current of the supercapacitor unit and a supercapacitor’s balancing device. Experimental and theoretical studies have been carried out in order to create supercapacitors with the maximum specific energy capacity. A mathematical model is proposed that establishes the relationship between the thickness of the energy storage component of the electrode and the materials from which the supercapacitor is made. Using the results of theoretical calculations and experimental data, a model of a supercapacitor with a specific energy consumption of 9.1 W h/kg was made. The obtained specific energy consumption is 25% higher than the specific energy consumption of the best samples of modern industrial supercapacitors.