Unveiling the efficient sodium storage and mechanism of MOFs-induced CoSe@N-doped carbon polyhedrons decorated with 2H-MoSe2 nanosheets

Abstract

Hybrid hierarchical nanostructures have a significant impact on engineering novel anode materials for boosting the performance of sodium-ion batteries (SIBs). Here, a hierarchical porous structure constituted by CoSe nanocrystals embedded in nitrogen-doped carbon polyhedron with the embellishment of 2H-MoSe2 nanosheets (CoSe@NC/MoSe2) is fabricated by a metal-organic frameworks (MOFs)-engaged strategy and subsequent selenization reaction. The presence of N-doped carbon matrix and bimetallic selenides significantly enhance electronic and ionic diffusion kinetics. In addition, the porous structure provides short Na+ diffusion distance and guarantees outstanding structural stability upon cycling. Due to these distinctive features, the CoSe@NC/MoSe2 composite displays superior cyclability of 305.9 mAh g−1 up to 1500 loops at 5.0 A g−1 and exceptional rate property of 286.1 mAh g−1 at 10.0 A g−1 for sodium storage. When matched with Na3V2(PO4)3@C cathode, a SIB full cell can maintain a high invertible capacity of 78.9 mAh g−1total over 100 loops at 0.5 A g−1. Moreover, the multistep conversion reactions mechanism is further identified by kinetics analysis, and ex situ and in situ characterization.