Superelastic and ultralight electrospun carbon nanofiber/MXene hybrid aerogels with anisotropic microchannels for pressure sensing and energy storage

As ultralight and superelastic aerogels are quite desirable for pressure sensing and energy storage applications, superelastic and ultralight carbon nanofiber (CNF)/transition metal carbides and carbonitrides (MXenes) hybrid aerogels with anisotropic microchannels are thus fabricated by liquid nitrogen-assisted unidirectional-freezing followed by freeze-drying. The CNFs with high aspect ratios entangle and assemble into the interconnected scaffolds, while the MXene sheets enhance structural stability of the framework of CNFs and endow the aerogels with satisfactory electronic conductivities. Benefiting from the stable architecture with orientated microchannels, the CNF/MXene aerogel (CNF/MX) with an ultralow density of 4.87 mg cm−3 exhibits superb compressible resilience at the strain of 50% for at least 5000 cycles and a high strain of 95% for 500 cycles. Importantly, the outstanding strain- or pressure-responses endow the CNF/MX aerogel sensor with high sensitivity (65 kPa−1), ultralow detection limit (<5 Pa), rapid response (26 ms), large workable strain range (0–95%), and superb response stability. Furthermore, the presence of MXene with excellent electrochemical activity makes the binder-free CNF/MX electrode exhibit a high rate performance with 80% capacitance retention when the current density increases by 100 times and a high cycling stability with capacitance retention of 90% after 20,000 cycles at 5 A g−1.