Independently double-crosslinked carbon nanotubes/polyaniline composite films as flexible and robust free-standing electrodes for high-performance supercapacitors

Abstract Flexible free-standing materials make the electrode fabrication process simple in comparison with the conventional binder-enriched electrodes, especially for those with desirable mechanical strength. In the present work, the crosslinked multi-walled carbon nanotubes (C-CNTs) films with tensile strength of >1.75 MPa, were prepared by facile filtering the dispersion of the micrometer-scaled 3-D framework of crosslinked carbon nanotubes with common water pump, and used as high-strength conductive skeleton for polyaniline (PANI). The preparing conditions were optimized for the best electrochemical property of the flexible C-CNTs/PANI composite films. As free-standing electrodes for supercapacitors, the highest specific capacitance of 507 F/g or 314 F/g, energy density of 70.4 or 43.6 Wh/kg and power density of 0.44 or 0.43 kW/kg were achieved with the in-situ chemical oxidative polymerization or solution coating technique, respectively. Then the independently double-crosslinked carbon nanotubes/polyaniline (C-CNTs/TC-PANI) composite films were obtained by thermal crosslinking (TC) the PANI coatings in the C-CNTs/PANI films. Their specific capacitance, energy density, and power density increased to 531 F/g and 455 F/g, 73.8 and 63.2 Wh/kg, 0.49 and 0.47 kW/kg with the in-situ chemical oxidative polymerization or solution coating technique respectively, and their electrochemical cyclic stability was also enhanced distinctly.