Constructing hierarchical dandelion-like molybdenum–nickel–cobalt ternary oxide nanowire arrays on carbon nanotube fiber for high-performance wearable fiber-shaped asymmetric supercapacitors

Abstract

Emerging fiber-shaped supercapacitors have been considered as promising new-state energy storage devices for next-generation wearable electronics. However, the limited energy densities arising from the small specific capacitance and low operating voltage severely restrict their practical application. Here, we develop a facile and effective method to directly grow dandelion-like molybdenum–nickel–cobalt ternary oxide (MNCO) nanowire arrays (NWAs) on carbon nanotube fiber (CNTF) with a high specific capacitance of 490.7 F cm⁻³ (1840 mF cm⁻²) at a current density of 1 mA cm⁻². Benefiting from the three-dimensional nanostructure, high conductivity and excellent pseudocapacitance properties, we successfully fabricate a fiber-shaped asymmetric supercapacitor (FASC) with a maximum operating voltage of 1.6 V, which is assembled by twisting a MNCO/CNTF positive electrode and thin carbon-coated VN NWAs on CNTF negative electrode together with KOH/poly(vinyl alcohol) (PVA) as the gel electrolyte. The optimized FASC delivers a remarkable specific capacitance of 62.3 F cm⁻³ (233.7 mF cm⁻²) and an exceeding energy density of 22.2 mW h cm⁻³ (83.1 μW h cm⁻²). Additionally, it exhibits outstanding flexibility with capacitance retention maintained at 90.2% after bending 3500 times. Thus, the high performance MNCO/CNTF electrode opens a new avenue to fabricate high-performance FASCs for next-generation wearable energy storage devices.