Expanding Interlayer Spacing in MoS₂ for Realizing an Advanced Supercapacitor

Charge-storage mechanism of free-standing MoS2/r-GO (r-GO = reduced graphene oxide) hybrid nanoflakes on molybdenum (Mo) foil in Na2SO4 solution is elucidated for realizing a high-performance asymmetric supercapacitor (ASC). Thiourea that acts primarily as sulfur source also helps intercalating ammonium ions, which along with r-GO facilitate in situ exfoliation of MoS2, producing hierarchical MoS2 with expanded interlayer spacing. This interlayer expansion in MoS2 facilitates Na+-ions intercalation/deintercalation and ensures enhanced capacitance, rate capability, and cycling stability of the capacitor. Besides exhibiting attractive energy-cum-power traits, the 2 V MoS2/r-GO//Fe2O3/MnO2 ASC shows compelling cycling performance for over 20 000 cycles in an aqueous electrolyte.