Electrodeposited crumpled MoS2 nanoflakes for asymmetric supercapacitor

Abstract

Transition metal chalcogenides are gaining attraction in the emerging energy-storing field owing to their captivating properties. Molybdenum disulfide (MoS2) was deposited on Ni foam by using a one-step electrodeposition method. X-ray diffraction study showed that the deposited MoS2 was amorphous, and X-ray photoelectron spectroscopy confirms the presence of Mo and S in the 4+ and 2+ oxidation states. Different nanostructures were observed by varying the deposition time, and MoS2 deposited for 300 s has an interconnected crumpled-nanoflake structure. The electrochemical performance of MoS2 electrodes was investigated between 0.2 and 1 V vs. SCE potential in 1M Na2SO4 electrolyte and the interconnected crumpled-nanoflake structure showed a maximum areal capacitance of 416.9 mFcm−2 at a current density of 1 mAcm−2. The charge storage kinetics of electrodes showed the diffusion-controlled contribution is greater than the capacitive-controlled contribution for MS-300 electrode. Also capacitive-controlled contribution is proportional to the scan rates. An asymmetric device was assembled using activated carbon and MoS2 as negative and positive electrodes respectively, which exhibited an areal capacitance of 277.3 mFcm−2 and energy density of 0.15 mWhcm−2 at 5.33 mWcm−2 power density measured at 3 mAcm−2 current density. Furthermore, 90.1% cyclability and excellent coulombic efficiency measured up to 3000 cycles were observed for an asymmetric device. These results depict the potential candidature of MoS2 and MoS2//AC devices as an emerging energy storing devices.