Metal organic framework derived hollow heterostructured NiS2/ZnS/C hybrid spheres for enhanced sodium-ion storage properties

Abstract

In this paper, we report the fabrication of metal organic framework (MOF)-derived heterostructured NiS₂/ZnS nanoparticles embedded in hollow carbon spheres (denoted as NiS₂/ZnS/C) using Ni-MOF as template precursor through a combined method of solvothermal, ion adsorption and subsequent sulfurization. The hollow spherical morphology and in-situ carbon layer confinement of active materials offer rich channels and paths for rapid ion/electron transport, alleviate the volume changes and agglomeration effect during cycling. Moreover, the built-in electric field created at the heterointerfaces of NiS₂/ZnS can promote the Na⁺ transport kinetics. Benefitting from these advantages, the optimal NiS₂/ZnS/C electrode shows a high reversible capacity (568 mAh/g at 1.0 A/g), superior rate property (401 mAh/g at 5.0 A/g) and outstanding long-term cycling stability (79 % retention over 3000 cycles at 5.0 A/g). This design concept is expected to be utilized for constructing other anode materials with heterostructures for SIBs.