Ni₃Se₄@CoSe₂ hetero-nanocrystals encapsulated into CNT-porous carbon interpenetrating frameworks for high-performance sodium ion battery

Core-shell structured Ni-ZIF-67@ZIF-8 derived bimetal selenides encapsulating into a 3D interpenetrating dual-carbon framework (Ni₃Se₄@CoSe₂@C/CNTs) have been designed and prepared via carbonization and subsequent selenization processes. In this hierarchical structure, Ni₃Se₄@CoSe₂ nanocrystals were uniformly dispersed into the 3D carbon frameworkstructure/carbon nanotubes networks, which greatly enhanced the electronic conductivity and further enabled ultrafast Na-ion diffusion kinetics. When used as anode materials of sodium ion battery (SIB), The Ni₃Se₄@CoSe₂@C/CNTs electrode delivered the excellent rate capability of 206 mA h g^-1 at 3 A g^-1 and marvelous cyclic stability with capacity retention of 243 mA h g^-1 after 600 cycles at 1 A g^-1. This research provides a new way to prepare bimetallic selenide derived from MOF precursor with amazing heterostructure as the advanced anode materials for SIBs.