Hierarchical nanothorns MnCo2O4 grown on porous/dense Ni bi-layers coated Cu wire current collectors for high performance flexible solid-state fiber supercapacitors

Abstract

Cu wires are coated by porous/dense Ni bi-layers as current collectors through electroless plating and hydrogen bubble dynamic template electrodepostion methods. The unique coaxial composite current collectors can be beneficial from the high electrical/thermal conductivity of metal Cu core and high corrosion resistance of dense metal Ni coating as well as porous Ni substrate for growth of active materials. Furthermore, the metal wire current collectors have excellent flexibility and mechanical strength. Highly flexible solid-state fiber supercapacitors are then fabricated by binder-free integrated electrodes of hierarchical MnCo2O4 nanothorns grown on porous/dense Ni bi-layers coated Cu wires. The fiber supercapacitors reach capacitance of 20.6 mF cm−1 (54.8 mF cm−2) and energy density of 4.8 μWh cm−1 (12.8 μWh cm−2) at a power density of 32.25 μW cm−1 (110 μW cm−2). Moreover, the twist fiber supercapacitors show good rate capability and cycling stability. The outstanding performances of the fiber supercapacitors might be attributed to the hierarchically nanothorns MnCo2O4 active materials and the unique porous/dense Ni coated Cu wire current collectors. Our results can provide a novel strategy to design flexible nanostructure fiber supercapacitors for energy storage applications in future wearable electronics.