Sewable high-performance poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/layered double hydroxide core-shell fiber electrodes for flexible supercapacitors

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based fibers are one of the most competitive fiber-type electrodes but still suffer from low electrochemical surface areas (ECSAs) and oversensitivity to humidity for fiber supercapacitor applications. Herein, through rational design, a sewable core-shell fiber electrode of PEDOT:PSS/waterborne polyurethane (WPU) fiber wrapped with nickel/cobalt-layered double hydroxides (NiCo-LDH) has been synthesized via wet-spinning and solution reaction. The fiber core acts as a conductive channel for charge carrier transport. The NiCo-LDH shell possesses unique hybrid architectures of honeycomb-like nanosheet array and hollow nanocages, which provide numerous electrochemical active sites. Simultaneously, the water barrier effect of the NiCo-LDH shell and the interaction between Co2+/Ni2+ and PSS reduce fiber water uptake, thus endowing the fiber with a better geometric stability with low swelling ratio. The as-prepared PEDOT:PSS/LDH fiber has a large ECSA (4060 cm2 g−1) and ultrahigh conductivities no matter in dry (1237.3 S cm−1) or wet (1018.7 S cm−1) state. It also exhibits a high capacitance (188.5 F g−1 at 1 A g−1) and long lifespan (capacitance retention of 94% after 10,000 cycles). The fiber-based supercapacitor shows superb flexibility with stable capacitive behavior under deformation. These characteristics manifest the potential of PEDOT:PSS/LDH fibers for stable high-performance energy storage to support wearable electronics.