Flexible two-ply yarn supercapacitors based on carbon nanotube/stainless steel core spun yarns decorated with Co3O4 nanoparticles and MnOx composites

- Carbon nanotube/stainless steel core-sheath yarns as electrode for two-ply supercapacitor.
- The yarns were decorated with Co3O4 nanoparticles and MnOx composites.
- Yarn electrodes deposited on Co3O4 and MnOx have excellent specific capacitance.
- The two-ply yarn supercapacitor based on MnOx has high energy density and power density.
- The yarn supercapacitors are highly flexible and strong for wearable electronics.

High performance two-ply yarn supercapacitors are fabricated by electrodeposition of transition metal oxide pseudocapacitive materials on carbon nanotube/stainless steel (CNT/SS) core spun yarns. The SS core incorporated in the carbon nanotube yarn has dramatically improved the conductivity of the substrate and the efficiency of electrodeposition of metal oxides on the electrodes. The SS core acts as current collector in the final two-ply yarn supercapacitors with significantly improved specific capacitance and up-scaled length of supercapacitors. Manganese oxide and cobalt oxide electrodeposited on as-spun CNT/SS yarn are compared for their electrochemical performance in two-ply yarn supercapacitors. Both supercapacitors displayed improvement in capacitance, energy and power densities, especially MnOx/CNT/SS yarn supercapacitor. The solid-state supercapacitor based on MnOx/CNT/SS composite yarn shows excellent electrochemical properties with a specific capacitance of 217.61 F/cm3 at 0.02 V/s and an energy density of 4.84 mWh/cm3 at a power density of 435.22 mW/cm3.

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