The conventional cell structure uses a separator to provide electrical insulation between the cathode and anode. In contrast, the surface of the new skin-coated electrode is coated with a nanofiber membrane. The ultra-thin insulating membrane makes it possible to minimize the distance between the cathode and anode. Increasing the porosity and thus the ion conductivity of the nanofiber membrane reduces internal electrical resistance, enhancing the input/output performance. In addition, since reducing the thickness of the insulating layer helps increase the battery capacity, the skin-coated electrode improves both input/output power and capacity.