Solvent-assisted self-assembly to fabricate a ternary flexible free-standing polyaniline@MXene-CNTs electrode for high-performance supercapacitors

MXene, a kind of booming two-dimensional (2D) nanomaterials, has exhibited a promising application on free-standing high-performance supercapacitors. However, researches on MXene-based cathodes are still under development because its susceptibility to oxidation. Herein, a flexible free-standing polyaniline@MXene-carbon nanotubes (CNTs) film was prepared by a delicately-designed solvent-assisted self-assembly method followed with a vacuum filtration process. The zero-dimensional (0D) polyaniline (PANI) nanoparticle, which is often used as a cathode nanomaterial, was coated on the surface of 2D MXene nanosheets by solvent-assisted self-assembly to prevent MXene from oxidation and provide high specific capacitance simultaneously. The one-dimensional (1D) CNTs were introduced to endow the composite with well mechanical strength and flexibility. The ternary composite film delivers an excellent mechanical performance with a tensile strength of 99.4 MPa, a high specific capacitance of 463 F g −1 at 5 mV s −1 , and good cyclic stability with 92 % capacitance retention after 10,000 cycles. The asymmetric supercapacitor device assembled with the ternary composite film as cathode and the prepared free-standing MXene-CNTs as anode achieves a high energy density of 10 Wh kg −1 and an exceptional power density of 2808 W kg −1 . • Uniform self-assembly of MXene and PANI nanoparticles is achieved. • CNTs endow the composite films with eminent mechanical strength and flexibility. • The free-standing PANI@MXene-CNTs films show excellent specific capacitance. • Asymmetric supercapacitors are composed of flexible free-standing films.