Copper molybdenum sulfide: A novel pseudocapacitive electrode material for electrochemical energy storage device

The ever-growing demand for energy storage devices necessitates the development of novel energy storage materials with high performance. In this work, copper molybdenum sulfide (Cu₂MoS₄) nanostructures were prepared via a one-pot hydrothermal method and examined as an advanced electrode material for supercapacitor. Physico-chemical characterizations such as X-ray diffraction, laser Raman, field emission scanning electron microscope with elemental mapping, and X-ray photoelectron spectroscopy analyses revealed the formation of I-phase Cu₂MoS₄. Electrochemical analysis using cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) showed the pseudocapacitive nature of charge-storage via ion intercalation/de-intercalation occurring in the Cu₂MoS₄ electrode. The Cu₂MoS₄ electrode delivered a specific capacitance of 127 F g^?1 obtained from the CD measured using a constant current density of 1.5 mA cm^?2. Further, Cu₂MoS₄ symmetric supercapacitor (SSC) device delivered a specific capacitance of 28.25 F g^?1 at a current density of 0.25 mA cm^?2 with excellent rate capability. The device acquired high energy and power density of 3.92 Wh kg^?1 and 1250 W kg^?1, respectively. The Nyquist and Bode analysis further confirmed the pseudocapacitive nature of Cu₂MoS₄ electrodes. The experimental results indicate the potential application of Cu₂MoS₄ nanostructures as a novel electrode material for energy storage devices.