Study on the MoN/Nitrogen-doped Graphene Sheets Composite for Lithium Ion Capacitor Electrode Materials

Molybdenum nitride/nitrogen-doped graphene sheets (MoN/NGS) composite was prepared via a simple hydrothermal method followed by calcination at 800 degrees C under ammonia atmosphere. The phase structure and morphology of samples were characterized by XRD and SEM. The electrochemical properties of composite electrodes were studied by performing cyclic voltammetry, galvanostatic charge and discharge, and electrochemical impedance spectroscopy test. The MoN/NGS electrode deliveres specific capacitance of 422 F/g at the current density of 0.05 A/g, and its capacitance retention remains more than 80% after 900 cycles. The energy density remains as high as 32.5 Wh/kg when the power density is 3000 W/kg. It should be noted that such improvement should be attributed not only to the presence of NGS in the composite offering an effective conducting network but also to the hybrid structure of MoN/NGS composite providing a favorable and fast ion transport and diffusion.