TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The electrolyte solution is a mixture of liquid electrolyte and an organic solvent.The organic solvent is at least one (preferably at least two) selected from propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxymethane, diethoxyethane, gamma-butyrolactone, acetonitrile, and/or propionitrile.The electrolyte solution has an electrolyte concentration of more than 0.5 mo/L. The liquid electrolyte is a salt containing cations and anions.The cation is made up of formula (I) (preferably 1,3-dialkylimidazolium or 1,2,3-trialkylimidazolium).R1, R2 = 1-5C straight chained alkyl;R3 = H or 1-5C straight chained alkyl.The anions are BF4-, PF6-, AsF6-, ClO4- or CF3SO3-.A short relaxation time component T2 of 20 - 50 micro sec (Gaussian type), a moderate relaxation time component T2 of 50 - 400 sec (Lorentzian type) and a long relaxation time component T2 of 500 - 2000 micro sec (Lorentzian type) which indicate variations in bonding state of hydrogen remaining in carbon tissue of the nonporous carbon and are observed by 1H resonance making use of pulsed NMR spectroscopy are found.The ratio of the moderate relaxation time component to the short relaxation time component is less than one-third.The nonporous carbon has a specific surface area of less than 270 (preferably less than 100)m2/g. EXAMPLE - A capacitor (test) comprising non-porous carbon (A704804+504H having average inter-planar spacing d002 of 0.360 mn, specific surface area of 100 g/m2, and relaxation component ratio of less than 0.20) and an electrolyte solution containing 1-ethyl-3-methylimidazolium.boron tetra-fluoride (EMI.BF4) without solvent was prepared. A comparative capacitor was prepared by using activated carbon having specific surface area of 1015 m2/g and maximum micropore frequency of 0.74 nm and tetraethylamine.BF4 as liquid electrolyte in acetonitrile and ethylene carbonate in equal volumes. Results of capacitance (g), applied voltage (V) and internal resistance (OMEGA) for test/comparative capacitors were 55.7/38.5, 4/3.75, and 9.9/10.3, respectively.