Freestanding MnO2 nanoflakes/porous carbon nanofibers for high-performance flexible supercapacitor electrodes

We report the facile synthesis of freestanding MnO2 nanoflakes/porous carbon nanofibers (MnO2/PCNFs) for high performance flexible supercapacitor electrodes. PCNFs are firstly synthesized via a electrospinning method using phenol-formaldehyde resin as the carbon precursor with tetraethyl orthosilicate and triblock copolymer Pluronic P123 as porous and soft templates, respectively. MnO2 nanoflakes are then in-situ deposited on PCNFs based on the self-limiting reaction between KMnO4 and carbon. The obtained MnO2/PCNF hybrid shows a porous structure with ultra-high specific surface area of 1814 m2 g−1, providing numerous electroactive sites to accommodate more charges. As a result, the MnO2/PCNF hybrid electrode exhibits extremely high specific capacitance (520 F g−1 at 0.5 A g−1) and superior cycling stability (92.3% retention after 4000 cycles) in a 6 M KOH aqueous solution. Such excellent electrochemical behavior may render this hybrid a promising candidate for flexible, freestanding and high-performance supercapacitor electrodes.