Hybrid Carbon Nanofibers Derived from MXene Nanosheets and Aromatic Poly(ether amide) for Self-Standing Electrochemical Energy Storage Materials

The microstructure, electrical and electrochemical properties of MXene/aromatic poly(ether amide) (PEA)-derived hybrid carbon nanofibers (HCNFs) as high-performance free-standing supercapacitor electrode materials are reported. For this purpose, a series of HCNFs are fabricated by sequential methods of electrospinning of PEA solutions, dip-coating (1-10 cycles) of as-spun PEA nanofibers into MXene aqueous dispersion, and heat-treatment of MXene-coated PEA nanofibers for carbonization. The structural analyses of HCNFs reveal that MXene nanosheets are uniformly deposited on PEA-derived and nitrogen self-doped CNFs and that they are accumulated with increasing the number of dip-coating cycles. Accordingly, the electrical conductivity increases from 3.94 S cm(-1) for PEA-derived neat CNF to 15.74 S cm(-1) for HCNF10 (10 dip-coating cycles) due to the increase in the content of electrically conductive MXene nanosheets. On the other hand, the electrochemical performance is measured to be the highest in HCNF7 (7 dip-coating cycles) owing to a trade-off effect of ion barrier function and high electrical conductivity of MXene nanosheets to porous CNF webs. For a symmetric supercapacitor setup of two self-standing HCNF7 electrodes, outstanding electrochemical properties of specific capacitance of 66.7-179.3 F g(-1), power density of 1000-10 000 W kg(-1), and energy density of 52.7-91.2 Wh kg(-1) are attained at current densities of 1-10 A g(-1).

Automated summary

This study reports the microstructure, electrical and electrochemical properties of MXene/PEA-derived hybrid carbon nanofibers (HCNFs) as high-performance supercapacitor electrode materials. The results show that MXene nanosheets are uniformly deposited on PEA-derived CNFs and that they contribute to the increase in electrical conductivity and electrochemical performance of the HCNFs.