Transition metal sulfide-laminated copper wire for flexible hybrid supercapacitor

Abstract

In this paper, we propose a flexible wire-type hybrid supercapacitor (FWHSC) endowed with superior electrochemical properties of transition metal sulfide nano-flakes. The electrodeposition method was conducted for coating of electroactive transition metal sulfide (CoS, NiCo₂S₄, CoS/NiCo₂S₄ and ZnCo₂S₄) nanomaterials on the current collector (Cu-wire), which makes it possible to store the electrochemical energy. The electrochemical study of NiCo₂S₄ and ZnCo₂S₄ electrodes revealed excellent charge storage features with areal capacitance of 245.5 and 104.6 mF cm⁻², respectively, at a scan rate of 2 mV s⁻¹. The FWHSC assembled from Cu@CoS/NiCo₂S₄ and Cu@ZnCo₂S₄ electrodes and KOH/PVA gel electrolyte operates in a voltage range of 1.5 V and delivers a specific energy of 6 W h kg⁻¹ at the specific power of 4500 W kg⁻¹ and a cycling stability of over 2000 cycles.