Facile construction of nano-core-yarn electrodes and capacitive performance

Purpose Linear supercapacitors as highly anticipated energy storage devices for smart clothing and wearable devices have excellent cycling stability, power density and integration. However, the small electrochemical window and low-capacitance storage capacity restrict the practical application of linear supercapacitors. 1T/2H mixed-phase Co-MoS2 were synthesized and further fibrillated by conjugated electrospinning herein with carbon fiber as core-yarn to improve the performance of assembled supercapacitors. Design/methodology/approach 2H-phase MoS2 and 1T/2H mixed-phase Co-MoS2 were synthesized by a simple hydrothermal method herein and further fibrillated by conjugated electrospinning and carbonization process with carbon fiber as core yarn. The constructed nano-Co-MoS2/carbon fiber core-yarn electrodes were further assembled as linear symmetric supercapacitor with PVA/LiCl gel electrolyte. Various concentrations of MoS2 or Co-MoS2 and process control during the spinning process were explored, and the morphological structure and electrochemical properties of the core-yarn electrodes were further compared and optimized. Findings The crystal plane spacing of 1T/2H mixed-phase Co-MoS2 increased from 0.62 nm to 0.96 nm with lattice defects due to cobalt doping, which increased the active reaction sites of MoS2, thus increasing the electrochemically stabilized voltage window and energy storage capacity. And the nano-core-yarn electrode as MSC-2 obtained by conjugate spinning of 1T/2H mixed-phase Co-MoS2 with addition of 3 Wt.% had a maximum electrochemically stable voltage window of 0–1.6 V, and a specific capacitance of 4.64 F g-1 was obtained at a scan rate of 10 mV s-1. Originality/value The presently developed wearable supercapacitors with light-weight, wide potential window, flexibility and freestanding are expected to be useful for new kinds of portable electric devices.