A self-charging supercapacitor is provided which includes a supercapacitor first electrode, a supercapacitor second electrode, a first electrolyte, and a metal electrode. The supercapacitor first electrode and the supercapacitor second electrode are parallel to and spaced apart front each other. The metal electrode and the supercapacitor second electrode form an Ohmic contact, the metal electrode is spaced apart from and opposite to the supercapacitor first electrode.