Rational design of ZIF-8 assimilated hierarchical porous carbon nanofibers as binder-free electrodes for supercapacitors

Recently, tremendous attention has been paid to carbon-based fibers, particularly porous carbon fibers (PCFs), because of their great potential as electrodes for advanced supercapacitors (SCs). However, the relatively complex preparation and monotonous pore structure are still the most important challenge that PCFs needs to counter. In this work, an eco-friendly yet facile approach has been applied to synthesis PCFs with tunable multi-level pores and satisfactory electrochemical performance. By using the combinations of electrospinning technology, hard-template method and carbonization process, nanofibers with interconnected multi-level pores can be achieved. It is demonstrated that the pore engineered PCF possesses enhanced electrochemical performance. For instance, the PCF electrode possesses a high capacitance of 211 F g−1 in 6 mol L−1 KOH at a density of 0.5 A g−1 together with excellent rate capability. Meanwhile, a high areal capacitance of 1.2 F cm−2 also can be achieved at a mass loading of 10 mg cm−2. Additionally, symmetrical supercapacitor assembled by PCF electrodes exhibits good capacitance of 101.9 F g−1 at the current density of 0.5 A g−1, such device also can deliver an energy density up to 60.1 Wh kg−1 with ionic liquid electrolyte.