Heterostructure of NiSe2/MnSe nanoparticles distributed on cross-linked carbon nanosheets for high-performance sodium-ion battery

Heterostructure of NiSe2/MnSe nanoparticles distributed evenly over cross-linked N-doped carbon nanosheets (NM@NCNs) was developed as anode material via a hydrothermal strategy followed by an in situ selenization process. The anode delivered a high reversible capacity of 487 mAh g(-1) at 5 A g(-1) after 200 cycles and an excellent rate capacity of 269 mAh g(-1) at a high current density of 10 A g-1. In particular, under-10 ?, the electrode still maintained a satisfactory rate capability for 271 mAh g(-1) at 5 A g(-1). The advanced electro-chemical performance is related with the following merits. First, NiSe2/MnSe nanoparticles as bimetallic selenide can offer a higher specific capacity than monometallic selenide. Moreover, the rich redox-active sites provided by NiSe2/MnSe can accelerate the electrochemical reaction. Second, cross-linked NCNs with high electronic conductivity can serve as a substrate, preventing nanoparticle agglomeration and alleviating the variations in vol-ume. Third, NiSe2/MnSe heterostructure proved by X-ray photoelectron spectroscopy (XPS) results can form lattice distortion, enhancing Na+ diffusion in the redox process. The possible electrochemical process was demonstrated by ex situ X-ray diffraction, and the Na+ diffusion rate of the NM@NCNs anode was calculated using the galvanostatic intermittent titration technique.

Automated summary

A heterostructure of NiSe2/MnSe nanoparticles evenly distributed on cross-linked N-doped carbon nanosheets has been developed as an anode material. This anode exhibits excellent electrochemical performance, with high reversible capacity and rate capability, attributed to the specific capacity of the bimetallic selenide nanoparticles and the electronic conductivity of the cross-linked carbon nanosheets.