Synthesis of MoS2/CoS composite electrode and its application for supercapacitors

Abstract

Molybdenum disulfide (MoS2) is one of the most explored prospective materials for building effective supercapacitors (SCs). However, low energy density hinders their efficiency due to poor electrical conductivity and deficient active sites. We designed a binder-free MoS2/CoS composite with nickel foam (NF) as a substrate to address these concerns. XRD, SEM, EDS and XPS were used to examine the structural and morphological development of the MoS2/CoS composite. The capacitive performance of MoS2/CoS electrodes was determined using CV, GCD and EIS. For the three-electrode system, the area specific capacitance of the MoS2/CoS electrodes was 180 mF/cm2 and 1931 mF/cm2 in Na2SO4 and KOH electrolytes respectively, with a current density of 5 mA/cm2. Also, the energy densities of SCs assembled in Na2SO4, and KOH electrolytes were 36.62 μWh/cm2 and 268.33 μWh/cm2, with power densities of 1345.22 μW/cm2 and 2100 μW/cm2, respectively. After 3000 cycles, the cycling stability of the devices in Na2SO4 (and KOH) electrolyte was about 71.2% (and 73.3%), implying good electrochemical stability of the devices. These results indicate the potential application of binder-free MoS2/CoS composites as electrode materials for aqueous SCs in KOH and Na2SO4 electrolytes.