Hybrid Polyaniline/Liquid Crystalline CNT Fiber Composite for Ultimate Flexible Supercapacitors

CNT fibers (CNTFs) are excellent platforms for fiber-shaped supercapacitors, offering both high electric conductivity and mechanical resilience. Here, we propose a polyaniline (PANI)/CNTF composite structure that utilizes a state-of-the-art liquid-crystal (LC)-spun CNTF as the ultimate conductive and flexible electrode. CNTFs assume a highly dense LC phase with a high electrical conductivity of 14 kS cm-1, which is similar to that of its metal counterpart and suitable as a good current collector. Pseudocapacitive PANI can be homogeneously polymerized directly onto the smooth surface of the CNTFs by using the sonochemical polymerization method. The optimized synthetic process produces PANI in a favorable chemical state with good contact properties at the CNTF interface, exhibiting a high capacitance (738 F g-1 at 1 A g-1) even at an extremely fast charge/discharge rate (604 F g-1 at 100 A g-1). Moreover, the superior mechanical resilience of the CNTFs enables excellent flexibility, showing a negligible capacitance decay after 15 »000 bending cycles, even with tight knots in the middle. These results highlight the excellent potential of highly densified CNTFs in next-generation flexible supercapacitors for practical wearable applications.