Surface functional treatment of carbon fiber with ultra wide potential range in neutral electrolyte for high performance supercapacitor

Abstract In this study, the oxygen-rich functional groups grafted carbon fiber cloth electrode (OCC) was successfully fabricated by activating carbon fiber cloth (CC) in strongly corrosive and oxidative environment, and the content of oxygen functional groups on surface of OCC can be easy controlled through different activation time. Surprisingly, the OCC electrode possesses an ultra wide potential range of −1.2 − 1.2 V in neutral electrolyte that is impossible to achieve in acidic or alkaline aqueous electrolyte, and the assembled symmetric supercapacitor device (SSD) exhibits a large operating voltage of 2.2 V. What's more, SSD presents high energy density of 0.87 mW·h cm−3 at power density of 5.5 mW cm−3 and superior cycling stability (86.8% of capacitance retention after 10,000 cycles). This study may provide a facile and available method for fabricating and designing flexible electrode with high performance.