A general strategy towards transition metal nitrides (TMNs)/rGO nanocomposites for superior lithium ion storage

Highlights: • A facile and practical route is developed to synthesize high-quality nanocomposites. • Uniform TMNs/rGO nanocomposites with controllable mass ratio and morphology are synthesized. • The TMNs/rGO nanocomposites exhibit much higher capacity, better rate and cycling performance than the pristine TMNs. -- Abstract: To address the growing concern for the rapidly increasing energy storage demand, it requires vigorous development of cutting-edge electrode materials to improve the lithium storage performance. Transition metal nitrides (TMNs), owning to the high electrical conductivity and considerable theoretical capacity, have attracted widespread attention as the electrode material for lithium ion storage. However, the volume variation and few active sites limit their applications. Herein, uniform TMNs/rGO (M=Nb, Fe) nanocomposites with controllable mass ratio and morphology are successfully synthesized, which can buffer the volume expansion effectively. As a result, the TMNs/rGO nanocomposites exhibit much better performance to the pristine TMNs. Specifically, the TMNs/rGO nanocomposites display a high reversible specific capacity (434.8 mAh g⁻¹ for Nb₄N₅/rGO and 463.0 mAh g⁻¹ for Fe₂N/rGO, respectively), excellent cycling performances (96.3% capacity retention over 1000 cycles and 97% over 2000 cycles at 1.0 A g⁻¹ for Nb₄N₅/rGO and Fe₂N/rGO, respectively). The effect of rGO is further investigated through quantitative kinetics analysis. This work demonstrates that the present versatile and expandable method can be developed to construct other high-quality nanocomposites for applications in energy storage, sensors, catalysis, etc.