Ultralight MXene/carbon nanotube composite aerogel for high-performance flexible supercapacitor

With the depletion of fossil resources and the gradual intensification of environmental pollution, green and sustainable electrochemical devices have aroused intensive attraction. The supercapacitor, demonstrating fast charging rate, high power densities, and long cycling life, has great application prospects in high power output and backup power supply. Herein, an ultralight and robust MXene/carbon nanotube aerogel is constructed by facile directional freezing and subsequent freeze-drying. Benefiting from the strongly π-π interactions between MXene nanosheets and carbon nanotube, the assembled MXene/carbon nanotube composite aerogel exhibits abundant pore structures, superior conductivity, and good mechanical properties. The electrical conductivity of MXene/carbon nanotube aerogel is up to 1600 S m−1. The MXene/carbon nanotube aerogel can be subjected to 70% compressive strain and retain 85% initial strain over 1000 compress-release cycles. The as-prepared all-solid-state supercapacitor with MXene/carbon nanotube aerogel shows outstanding electrochemical performance (410.7 mF cm−2 at the current density of 0.8 mA cm−2). The supercapacitor is flexible and can be bent from 0 to 90° as the cyclic voltammetry curves are almost consistent. Furthermore, the LED can be lighted by four devices in series.