Low resistance VFG-Microporous hybrid Al-based electrodes for supercapacitors

Abstract

It is a challenge to find low-cost graphene-based Al electrodes with a low resistance for a high-performance supercapacitors. For this purpose, we have developed new 3D hybrid structure electrodes composed of vertically oriented few-layer graphene (VFG) grown in situ on Al foil with a microporous structure (VFG/3D-Al). The 3D VFG-Microporous hybrid structured electrode shows a higher specific capacitance than that of a conventional VFG/plane-Al electrode in both aqueous and organic electrolytes. Furthermore, the VFG shows excellent wettability in organic electrolytes, whereby the effective reaction area between the VFG and electrolyte is higher than that in aqueous electrolytes. Thus, the VFG/3D-Al electrode exhibits a high specific capacitance of 1398μF/cm2 (the volumetric specific capacitance up to 139F/cm3) in organic electrolytes, and retains over 90% capacitance after 12,000 cycles. Moreover, the interface of the VFG/Al is modified and shows low contact resistance because the oxide film at the Al surface is removed by plasma etching and Al4C3 is formed at the interface of VFG/Al. This work paves a feasible pathway for the preparation of low-resistance VFG/3D-Al hybrid electrodes for supercapacitors.