▎ 摘　　要

NOVELTY - A water system electrolyte preparing method involves weighing nano-titanium dioxide solution with certain concentration, adding certain concentration of graphene oxide solution in proportion during stirring and ultrasonically treating, spray-drying and heat-treating the mixture to obtain a titanium dioxide/reduced graphene oxide nano-composite, preparing the positive and negative pole pieces with titanium dioxide/reduced graphene oxide nano-composite material and activated carbon as active materials, using a solution of lithium bistrifluoromethane xanide and lithium trifluoromethanesulfonate to obtain a mixed double salt concentrated solution electrolyte, and adjusting the pH value of the electrolyte with a bistrifluoromethane yellow imide solution, the positive and negative electrode sheets and the electrolyte are assembled into a lithium ion capacitor. USE - Method for preparing water system electrolyte for lithium ion capacitor. ADVANTAGE - The method enables preparing water system electrolyte with high voltage and power density and energy density and enhanced performance of the lithium ion capacitor.