Microwave-assisted synthesis of nitrogen-doped pineapple leaf fiber-derived activated carbon with manganese dioxide nanofibers for high-performance coin- and pouch-cell supercapacitors

Herein, a composite between porous, N-doped, pineapple leaf fiber-derived activated carbon (PALF-NAC) and α-MnO2 nanofibers was investigated as an electrode material for high-performance supercapacitors (SCs). The nitrogen doping of pineapple leaf fiber-derived activated carbon resulted in an increase in N content from undetectable level to 2 wt%. PALF-NAC and α-MnO2/PALF-NAC possessed mesoporous structures with high specific surface areas of 1054 and 772 m2 g−1, respectively. According to the three-electrode electrochemical measurement, the α-MnO2/PALF-NAC electrode in 1 M H2SO4 had a high specific capacitance of 195 F g−1 at 0.1 A g−1. In a coin-cell SC, this electrode in 1 M H2SO4 exhibited a high specific capacitance of 133 F g−1 at a specific current of 0.1 A g−1, with an excellent capacitance retention of up to 84.5% over 10000 charge–discharge cycles at the specific current of 0.5 A g−1. An SC pouch cell employing the same electrodes and electrolyte revealed a high capacitance of 120 F at the current rating of 10 mA, with the energy and power of 26.8 Wh and 120.5 W, respectively. Thus, this new α-MnO2/PALF-NAC electrode can be used to develop stable, cost-effective, and high-performance supercapacitors.