Coaxial Cable-Like Carbon Nanotubes-Based Active Fibers for Highly Capacitive and Stable Supercapacitor

Polyoxometalate (POM) as one pseudocapacitive material could efficiently boost the capacitance of carbon materials. However, POM hydrolysis is a key obstacle in utilizing POM for supercapacitors, causing reduced cycling stability. Here, coaxial cable-like carbon nanotubes(CNTs)-based active fibers are synthesized for highly capacitive and stable supercapacitors. The POM layer of PMo12O403-(PMo) is physically protected from the hydrolysis by the external polyaniline (PANI) layer. The optimal CNT/PMo/PANI fibers show a highly specific capacitance of 825 F g(-1)at 5 A g(-1)and excellent cycling stability (approximate to 85% retention at 6000th cycle). However, the control structure of CNT/PANI/PMo only deliver 486 F g(-1)at 5 A g(-1)and 64% capacitance retention achieved after 500 cycles. The significant improvements of CNT/PMo/PANI can be attributed to the synergistic effect of CNTs, PMo, and PANI. CNTs serve as a 1D charge transport expressway and anchor through poly(diallyldimethylammonium chloride) linkers. PMo clusters and PANI serve as the main active centers for fast reversible redox reactions, contributing pseudocapacitance. PANI serves as a shield layer for maintaining the integrity of PMo clusters and thus ensure good stability.