Molybdenum Nitride and Oxide Quantum Dot @ Nitrogen-Doped Graphene Nanocomposite Material for Rechargeable Lithium Ion Batteries

Abstract

A multistage architecture with molybdenum nitride and oxide quantum dots (MON-QDs) uniformly grown on nitrogen-doped graphene (MON-QD/NG) is prepared by a facile and green hydrothermal route followed by a one-step calcination process for lithium ion batteries (LIBs). Characterization tests show that the MON-QDs with diameters of 1–3 nm are homogeneously anchored on or intercalated between graphene sheets. The molybdenum nitride exists in the form of crystalline Mo2N (face-centered cubic), while molybdenum oxide exists in the form of amorphous MoO2 in the obtained composite. Electrochemical tests show that the MON-QD/NG calcinated at 600 °C has an excellent lithium storage performance with an initial discharge capacity of about 1753.3 mAh g−1 and a stable reversible capacity of 958.9 mAh g−1 at current density of 0.1 A g−1 as well as long-term cycling stability at high current density of 5 A g−1. This is due to the multistage architecture, which can provide plenty of active sites, buffer volume changes of electrode and enhance electrical conductivity as well as the synergistic effect between Mo2N and MoO2.