A facile synthesis of 2D bimetallic solid solution nitrides for robust stability in lithium-ion battery

Abstract

Nanostructured transition metal nitrides (TMNs) demonstrate immense promise for lithium-ion battery applications owing to their outstanding conductivity and high theoretical capacity. However, challenges such as the expansion of volume, aggregation concerns, and rapid capacity decay still need to be effectively addressed. Herein, a facile synthesis of 2D nitrides, including TiVN, NbVN and TiNbN, is achieved through nitriding their corresponding MXenes. The distinct 2D layered structure enables them fast lithium-ion transport and inhibits volume variation, thereby improving rate performance and stability. Moreover, the incorporation of bimetallic elements in solid solution induces lattice distortion, creating lattice vacancies and increasing lithium storage capacity. Atomic-level interactions within solid solutions, confirming by the shifts of binding energy, contribute to improved structural stability and accelerated charge transfer. The theoretical calculation further proves that the bimetallic solid solution structure elevates the d-band center and increases the Li+ adsorption energy. Consequently, the synthesized TiVN, NbVN and TiNbN demonstrate remarkable lithium storage performance. Especially, NbVN with a porous morphology stands out by achieving a specific capacity of 216.6 mAh/g after 1,400 cycles at 1 A/g, significantly outperforming Nb4N5 and VN. This work may provide valuable insights for the efficient synthesis and electrochemical applications of two-dimensional solid-solution nitrides.