Rational Design of Hierarchical Titanium Nitride@Vanadium Pentoxide Core–Shell Heterostructure Fibrous Electrodes for High-Performance 1.6 V Nonpolarity Wearable Supercapacitors

Extensive progress has been made in fiber-shaped asymmetric supercapacitors (FASCs) for portable and wearable electronics. However, positive and negative electrodes must be distinguished and low energy densities are a crucial challenge and thus limit their practical applications. This paper reports an efficient method to directly grow TiN nanowire arrays@V₂O₅ nanosheets core-shell heterostructures on carbon nanotube fibers as nonpolarity electrodes. Benefiting from their unique heterostructure, single electrodes possess high specific capacitances of 195.1 and 230.7 F cm^-3 as positive and negative electrodes, respectively. Furthermore, all-solid-state nonpolarity FASC devices with a maximum voltage of 1.6 V were successfully fabricated. Our devices achieve an outstanding specific capacitance of 74.25 F cm^-3 and a remarkable energy density of 26.42 mW h cm^-3. More importantly, their electrochemical performance changed negligibly regardless of whether the charge-discharge process is in positive or negative direction, indicating excellent nonpolarity. Therefore, these high-performance nonpolarity FASCs pave the way for next-generation wearable energy storage devices.