Decoration of carbon encapsulated nitrogen-rich Mo N with few-layered MoSe2 nanosheets for high-performance sodium-ion storage

The carbon encapsulated nitrogen-rich Mo x N is decorated by few-layered MoSe 2 nanosheets after the rational design. It is found that the Mo x N as a substrate is the basis for long cycling stability, and the few-layered MoSe 2 nanosheets are the key to improving the actual capacity for sodium-ion storage. Transition metal nitrides have become the focus of research in sodium ion batteries (SIBs) due to their unique metal properties and high theoretical capacity. However, the low actual capacity is still the main bottleneck for their application. Herein, using Mo-aniline frameworks as precursors, the carbon encapsulated nitrogen-rich Mo x N is decorated by few-layered MoSe 2 nanosheets (MoSe 2 @Mo x N/C-I) after the facile calcinating, selenizing, and nitriding. The carbon encapsulation can effectively strengthen the structural stability of Mo x N. The nitrogen-rich Mo x N and decoration of few-layered MoSe 2 can create rich heterointerfaces and extra active sites for rapid sodium-ion storage, thus promoting reaction kinetics and improving actual capacity. The MoSe 2 @Mo x N/C-I as an anode achieves a large reversible capacity of 522.8 mAh g −1 at 0.1 A g −1 , and 254.3 mAh g −1 capacity is obtained after 6000 cycles at 5.0 A g −1 , showing signally improved sodium-ion storage properties. The storage mechanisms and kinetic behaviors are described systematically via the advanced testing techniques and density functional theory (DFT) calculations. It is found that the nitrogen-rich Mo x N as the substrate is the basis of long cycling stability, and the few-layered MoSe 2 are the key to improving actual capacity. This work indicates that the decoration of few-layered selenides has a broad application prospect in high-performance metal-ion batteries.