In this work, hierarchically porous composites were prepared in the form of activated carbon cloth (CC) Busofit T–1–055 filled with an electrically conductive polymer, polyaniline (PANI), for use as pseudocapacitive electrodes of electrochemical supercapacitors (SCs). CC fibers have high nanoporosity and specific surface area, so it was possible to deposit (via the chemical oxidative polymerization of aniline) a significant amount of PANI on them in the form of a thin layer mainly located on the inner surface of the pores. Such morphology of the composite made allowed the combining of the high capacitive characteristics of PANI with the reversibility of electrochemical processes, high columbic efficiency and cyclic stability rather typical for carbon materials of double-layer SCs. The highest capacitance of composite electrodes of about 4.54 F/cm² with high cyclic stability (no more than 8% of capacity loss after 2000 charge–discharge cycles with a current density of 10 A/cm²) and columbic efficiency (up to 98%) was achieved in 3 M H₂SO₄ electrolyte solution when PANI was synthesized from an aniline hydrochloride solution with a concentration of 0.25 M. Trasatti analysis revealed that 27% of specific capacitance corresponded to pseudocapacitance, and 73% to the double-layer capacitance.

Experimental results of depositions of thin Ti, La, Pb, Cd, Mn, Zr, and Y oxide films on the surface of a 50-μm-thick aluminum foil, used for manufacturing electrolytic capacitors by the pyrolysis method of salts of carboxylic acids, are presented. The obtained samples are characterized by capacitance values of 40 to 240 μF/cm² and electric strength values in an interval of 0.5 to 2 V, except for Ti oxides, whose samples have an electric strength of 2 to 8 V. The obtained capacitance and electric strength values are close to the values possessed by commercially produced aluminum foils with thicknesses of 70–107 μm having an aluminum oxide dielectric on the surface.

Results of a systematic study of propylene carbonate (PC) based organic electrolytes with alkylammonium tetrafluoroborates for use in supercapacitors (SC) for portable electronics and self-charging power sources have been presented. The importance of the study is dictated by the requirement to combine SC high power capacity, electrochemical stability over a wide temperature range, and operation safety, especially in independent miniaturized devices. Unlike acetonitrile (AN) conventionally used in SC electrolytes, PC is not noxious and non-flammable, but its high viscosity limits the electrical conductivity of electrolytes thus making the choice of optimum ionogenic salt a critical task. The properties of PC-based electrolytes with tetraethylammonium (TEA·TFB), methyltriethylammonium (TEMA·TFB), spiro-(1,1’)-bipyrrolidinium (SBP·TFB), and 1,1-dimethylpirrolidinium (DMP·TFB) tetrafluoroborates, differing in the size and structure of cations (acyclic and cyclic) have been studied. All the test salts deliver approximately similar capacities of SC cells, but TEA·TFB demonstrates somewhat lower capacity due to the large size of its cation. Ionogenic salts with cyclic cations (SBP·TFB and, especially, DMP·TFB) provide a far greater range of operation voltage at elevated temperatures to 85 °C, whereas TEA·TFB and TEMA·TFB electrolytes degrade at above 60 °C. Durability tests (up to 70,000 cycles at 50–95 °C) confirmed the electrochemical and thermal stability of DMP·TFB+PC: SC cells with the latter electrolyte retain 80 % of initial capacity after 50,000 cycles of galvanostatic charging/discharging (GCD) and provide for an operation voltage of 3.0 V. The recommended operation temperature range for SC with DMP·TFB+PC electrolyte is 0 to 85 °C, with the possibility of short-time temperature growth to 95 °C, whereas at below 0 °С the growing viscosity of the electrolyte causes a dramatic degradation of SC capacity. Thus, DMP·TFB+PC electrolyte is promising for SC used in portable electronics.