ИСТИНА

The problem of energy accumulation and storage is a factor affecting the further development of various technical devices, such as hybrid electric vehicles, mobile electronic devices, solar panels, memory backup systems, medical devices, etc. Supercapacitors (SCs) currently are the most promising devices for this purpose. A classic SC is an electrochemical capacitor based on the double electric layer in which carbon materials with a high specific surface area are used as electrodes. Such SCs have high power density, however, their energy density is significantly below the energy density of Li-ion batteries. Besides, there is an insufficient cycling stability with such devices in charge/discharge cycles. In order to improve specific characteristics of the supercapacitor, a combination of pseudocapacitances of both enzymatically synthesized polyaniline/multi-walled carbon nanotubes composite (PANI/MWCNT) and gel polymer redox electrolyte was used. The PANI/MWCNT composite has a core shell structure. The gel of polyvinyl alcohol in sulfuric acid containing sodium 1,2-naphthoquinone-4-sulfonate (PVA/H2SO4/NQS) was applied as a gel polymer redox electrolyte. The electrochemical studies have shown that the redox behavior of NQS is a diffusion-controlled and quasi-reversible process. The PANI/MWCNT composite in 13 mM NQS solution had a high specific capacitance of ca. 1100 F/g at the scan rate of 5 mV/s. The symmetrical flexible SC device based on the PANI/MWCNT composite and the PVA/NQS gel redox electrolyte had the power density of ca.1.0 kW/kg and the energy density of ca. 28.0 Wh/kg. After 3000 cycles of the potential scanning, the specific capacitance of the SC device decreased by less than 7%.