Freestanding ion gel and method for preparing the same

Disclosed is preparation of a freestanding ion gel having high stability and high ionic conductivity based on surface-activity ionic liquids. Further, disclosed is a solid electrolyte using the ion gel. A method for preparing the freestanding ion gel include mixing a surface-activity ionic liquid having an alkyl group having 8 or greater carbon atoms, a crosslinking agent, water and oil with each other to form a bicontinuous microemulsion mixture; ii) adding an initiator to the mixture; and iii) curing the mixture using ultraviolet (UV) or thermal energy to form a freestanding ion gel.