Cotton Fabric-Derived Hybrid Carbon Network with N-doped Carbon Nanotubes Grown Vertically As Flexible Multifunctional Electrodes for High-Rate Capacitive Energy Storage

The emerging electronic textiles (e-textiles) with various functionalities urgently demand the flexible textile -based supercapacitors (TSCs) as reliable power sources. The textiles used for energy storage generally serve as supports/current-collectors and thus hardly contribute capacitance in contrast to electrochemically active ma-terials. Herein, ultralong N-doped carbon nanotubes (NCNTs) are grown directly on the hollow textile carbon (TC) fibers to yield highly conductive TC-NCNTs hybrid network (20.4 S cm(-1)) through a facile one-pot heating strategy, allowing rapid ion and electron kinetics along this 3D interlaced backbone. Electrochemical oxidation of TC-NCNTs for 20 min yields the EATC-NCNTs-20 electrode with an enhanced areal capacitance of 1279 mF cm(-2) due to the introduction of tremendous oxygen functional groups. Meanwhile, electrodeposition of CoS nanosheets on TC-NCNTs offers large accessible surface area for pseudocapacitive redox reactions, leading the TC-NCNTs@CoS-8 electrode to achieve an areal capacitance of 2240 mF cm(-2) at 5 mA cm(-2), together with a remarkable rate performance (92.6 % capacitance retention at 100 mA cm(-2) with CoS mass loading of 10.8 mg cm(-2)). A flexible asymmetric supercapacitor fabricated with the two electrodes delivers an energy density of 2.30 mWh cm(-3) at 24.27 mW cm(-3). These results could promote the development of advanced textile-based electrochemical energy storage devices.