Synergistic effect of two-dimensional additives on carbon nanotube film electrodes towards high-performance all-solid-state flexible supercapacitors

Flexible supercapacitors (SCs) have attracted growing interest as the power source for portable and wearable electronics. In the present work, we report the CNTs (Carbon Nanotubes) buckypaper integrated with electro-active 2D materials including graphene, graphene oxide (GO), and transition metal sulphides (TMDs), especially tin sulphide (SnS2). The flexible and free-standing, interface-enhanced CNT paper having homogeneously dispersed 2D materials was prepared using a traditional scalable casting method. The hybridized CNT films were thoroughly characterized to elucidate their structural and surface properties. Finally, such hybrid CNT films were used as free-standing electrodes without any binder for the fabrication of flexible-solid-state supercapacitor (FSSSs) devices. In the FSSS, the electrochemical interactions between hybrid CNT paper electrodes and a polymer gel electrolyte were studied. In the symmetric configuration, the CNT-SnS2 electrodes reach the highest areal and volumetric capacitance of 533 mF/cm2 and 63 mF/cm3, respectively, almost four times that of pristine CNT electrodes, whereas CNT-GO-based electrodes display high-rate capability. The CNT-SnS2-based symmetric FSSS devices exhibit an extended voltage window of 1.5 V with a high capacitance of 133 mF/cm2 and show high cyclic stability for 5000 cycles under 180 0 bendings.

Automated summary

Flexible supercapacitors have attracted attention as power sources for portable and wearable electronics. This study integrates carbon nanotube (CNT) buckypaper with 2D materials including graphene, graphene oxide, and transition metal sulphides, especially tin sulphide. The hybrid CNT films, prepared using a scalable casting method, are used as electrodes for flexible-solid-state supercapacitors. The symmetric FSSS devices with CNT-SnS2 electrodes demonstrate high capacitance, high cyclic stability, and extended voltage window.