Carbon based nanomaterials like carbon nanotubes and graphene are often regarded as one of the most promising candidates for future nanoelectronic devices. To maximize their potential capabilities, chemical modulation and property control such as doping, functionalization and unzipping of graphitic planes are essential. Among them, unzipping of carbon nanotubes is in high demand to enable customizing structures and properties for different applications. However, previous unzipping processes have been based on chemical oxidation under harsh acidic condition leading to form many defects on the graphene basal plane and degrade electrical, magnetic, and mechanical properties. Herein, we present heteroatom dopant specific unzipping reaction of carbon nanotubes without any defects via electrochemical method. The resultant nanostructures consisting of unzipped graphene nanoribbons wrapping around the carbon nanotube cores maintain the atomically crystalline graphitic structures with well-defined atomic configuration at the unzipped edges. The synergistic effects of enhanced surface area and high electrical conductivity demonstrate ultrahigh-power supercapacitor performance.