<p>Mutually complementary research methods indicate that an electrode material based on carbonized sapropelic coal filled with silver nanoparticles is very promising for use in supercapacitor electrodes. In identifying the optimal conditions for applying the silver nanoparticles to the surface of the carbon matrix, three options are considered: with no reducing agent; with sodium tetrahydroborate; and with hydrazine hydrate. The option with no reducing agent yields the optimal capacitance. Charge accumulation in the electrodes is mainly due to a double electrode layer. The mean capacitance of the composites (537 F/g) is 20% higher than that of the basic carbon material (435 F/g). Impedance spectroscopy indicates that the capacitance is higher for the composite on account of the overall decrease in the electrical resistance. The decrease in resistance of the nanocomposite is greatest when applying the silver nanoparticles to the surface of the carbon matrix with no reducing agent.</p>