Carbon nanofibers derived from bacterial cellulose: Surface modification by polydopamine and the use of ferrous ion as electrolyte additive for collaboratively increasing the supercapacitor performance

摘要

Carbon nanofibers (CNF) materials have been produced via the freeze-drying and carbonization processes, using commercial bacterial cellulose as carbon precursor. Then, the surface of CNF is modified by polydopamine (PDA), which largely deteriorates the surface area and pore volume but enhances the wettability. What's more, ferrous ion (Fe2+) is introduced as redox additive, which has remarkably boosted the capacitive performance. The optimal sample delivers a high energy density of 10.07 Wh kg(-1) at 1 kW kg(-1) and large capacitance of 219F g(-1) at 10 A g(-1). Moreover, what attracts us is that the sample's increase fold (similar to 10.17 times) is quite high, far exceeding the performance of common redox additives. Besides, it indicates favorable long-term cycling stability within 10,000 times (the capacitance retention up to 95%). The present strategy of PDA coating on carbon surface and use of redox additive pay the way to collaboratively boost the performance of supercapacitors.