Vertical few-layer graphene/metalized Si-nanocone arrays as 3D electrodes for solid-state supercapacitors with large areal capacitance and superior rate capability

A strategy to promote the energy density of graphene-based supercapacitors by a combination of dry etching and chemical vapor deposition (CVD) techniques is demonstrated. A three dimensional (3D) electrode is composed of vertically oriented graphene that is deposited on metalized silicon nanocones. The design of the 3D electrodes improves specific surface area, electrolyte ion migration and electrical contact, resulting in an enhancement of areal capacitance and rate capability. Furthermore, a solid-state supercapacitor was prepared based on the 3D graphene electrodes and gel polymer electrolyte. The 3D electrode with 10 min of CVD growth of graphene endows the electrical double layer capacitor with the highest areal capacitance of 667.2 μF cm−2, which is larger than that of supercapacitors with flat electrodes.