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

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.