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

Abstract

Abstract 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 PMo 12 O 40 3− (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 (≈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.