The present invention relates to the electrochemical field, particularly to an electrolyte solute and an electrolyte that are used for a high-voltage supercapacitor, and a high-voltage supercapacitor using the electrolyte. The anion of the electrolyte solute may be one or more selected from tetrafluoroborate, hexafluorophosphate, bis(trifluoromethylsulfonyl) imide, tris (trifluoromethylsulfonyl) methyl and perfluoroalkyl sulfonate, and the cation may be N-methyl-1,4-diazabicyclo[2.2.2]octane ammonium, N,N-dimethyl-1,4-diazabicyclo[2.2.2]octane ammonium, N-methyl-1-azabicyclo[2.2.2] octane ammonium. The high-voltage supercapacitor fabricated by using the electrolyte formulated by the electrolyte solute of the present invention can work stably for a long period of time at a voltage of 2.7 V to 3.2 V, the energy density is greatly increased, the property of high power density is maintained, and the working life is prolonged.