MnCo2O4@nitrogen-doped carbon nanofiber composites with meso-microporous structure for high-performance symmetric supercapacitors.

Abstract The electrochemical properties of carbon nanofibers for supercapacitor application should be improved to meet the requirement of renewable energy systems. Herein we investigate the effect of MnCo 2 O 4 on the electrochemical properties of carbon nanofibers. Nitrogen-doped carbon nanofibers incorporated with MnCo 2 O 4 nanoparticles are synthesized by carbonizing manganese-cobalt@polyacrylonitrile nanofibers under N 2 atmosphere. The composite electrode-based symmetric supercapacitor at an optimum loading of 1/2 mmol has an excellent specific capacitance of 871.5 F g−1 (at a current density of 0.5 A g−1), presents an ultra-high energy density of 30.26 Wh kg−1 and delivers an excellent cycle performance (retention rate of 89.3% after 5000 cycles). The outstanding electrochemical properties of composite electrode are mainly attributed to the doping of nitrogen and the introduction of MnCo 2 O 4 into carbon matrix. The adoption of PAN is aimed to produce the doped nitrogen in carbon bulk, which can generate pseudocapacitance and improve the electrical conductivity of carbon nanofibers. The introduction of MnCo 2 O 4 results in the formation of meso-microporous structure in CNFs, which facilitates the rapid and efficient transfer of charges into the electrode material. Besides, MnCo 2 O 4 is an active material for pseudocapacitors that can undergo redox reaction during charge/discharge process, thus enhancing the electrochemical performance of carbon nanofibers. Graphical abstract Image 1 Highlights • MnCo 2 O 4 @N-CNF is fabricated by carbonization in N 2 atmosphere. • The addition of MnCo 2 O 4 to CNF induces meso-microporous structure. • MnCo 2 O 4 @N-CNF shows high specific capacitance of 871.5 F g−1. • Symmetric supercapacitor can deliver a high energy density of 30.26 Wh kg−1. • Good cyclability with more than 89.3% capacitive retention after 5000 cycles. [ABSTRACT FROM AUTHOR]