TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Properties: The weight decrease amount of the electrolyte when left still at a pressure of 10 Torr and a temperature of 60 degrees C or 150 degrees C for 1 hour is 1 %mass or less with respect to the mass of electrolyte before leaving. The moisture content in the electrolyte is 50 mass ppm or less. Preferred Composition: The electrolyte contains a solvent having lower boiling point than water. The solvent is chosen from alcohol solvent, ketone solvent, ether solvent, and hydrocarbon-based solvent, preferably methanol, ethanol, 1-propanol, 2-propanol, acetone, methyl ethyl ketone, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, n-heptane, cyclohexane, methylcyclopentane, cyclopentane, tetrahydrofuran, diisopropyl ether, methyl-t-butyl ether, and/or 1,2-dimethoxyethane. The electrolyte further contains an organometallic compound of formula: M(OR)x as dehydrating agent.M=Si, Ge, Sn, Pb, Al, Ga, In or Tl, preferably Si or Ge;R=1-4C alkyl, preferably methyl or ethyl;andx=3 or 4.The electrolyte further contains an ionic liquid. The cation of ionic liquid is ammonium, phosphonium cation, and/or sulfonium cation. The anion of ionic liquid is tetrafluoroborate anion, tetrafluoroaluminate anion, hexafluorophosphate anion, hexafluoroarsenate anion, hexafluoroantimonate anion, perchlorate anion, aluminum tetrachloride anion, trifluoromethanesulfonate anion, pentafluoroethanesulfonate anion, heptafluoropropanesulfonate anion, perfluorobutanesulfonate anion, methanesulfonate anion, ethanesulfonate anion, methyl sulfate anion, ethyl sulfate anion, bis(fluorosulfonyl)imide anion, bis(trifluorosulfonyl)imide anion, trifluoroacetate anion, bis(perfluoroethylsulfonylimide) anion, bis(perfluorobutylsulfonylimide) anion, tris(trifluoromethylsulfonyl)methide anion, tris(perfluoroethylsulfonyl)methide anion, dicyanoazanide anion, and/or phosphate anions ((CF3)3PF3-, (C2F5)3PF3-, (C3F7)3PF3-, (C4F9)3PF3-). Preferably, the cation is N-ethyl-N-methyl piperidinium, N-methyl-N-propyl piperidinium, N-butyl-N-methyl piperidinium, N-hexyl-N-methyl piperidinium, N-ethyl-N-methyl pyrrolidinium, N-methyl-N-propyl pyrrolidinium, N-butyl-N-methyl pyrrolidinium, N-hexyl-N-methyl pyrrolidinium, N,N,N-trimethyl-N-ethylammonium, N,N,N-trimethyl-N-propylammonium, N,N,N-trimethyl-N-butylammonium, N,N,N-trimethyl-N-hexylammonium, N,N,N-triethyl-N-methylammonium, and/or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium. Preferably, the anion is bis(fluorosulfonyl)imide anion, bis(trifluorosulfonyl)imide anion, or bis(perfluoroethylsulfonylimide) anion. The electrolyte further contains a polymer.