Geometry-controllable graphene layers and their application for supercapacitors

A facile and ultrafast method for geometry controllable and vertically transformative 3D graphene architectures is demonstrated. The 2D stacked graphene layers produced by exfoliation of graphite were transformed, e.g., from horizontal to vertical, by applying electric charge (-2 V with 1-3 μAh/cm²). The three-dimensionally transformed graphene layers have maximized surface area as well as high specific capacitance, 410 F g^-1 in LiClO₄/PC electrolyte, which is 4.4 times higher than that of planar (stacked) graphene layers. Furthermore, they can remarkably exhibit 87% of retained capacitance as the scan rate is increased from 100 to 1000 mV s^-1, unlike planar graphene, which displays 61% retention under the same conditions.