A hollow Double-Shell CoSe2@Carbon hybrid for High-Performance electrochemical sodium storage.

A Co-MOF-74-derived DS-CoSe 2 @C-600 hybrid was designed to unite the merits of both hollow double-shell structure and plum pudding-like structure for optimized electrochemical Na+ storage performance. [Display omitted] • The formation mechanism of hollow doubel-shell MOF-74 is elaborated. • Hollow doubel-shell CoSe 2 @C hybrid shows superior Na+ storage performance. • Electrochemical Na+ storage performance is discussed in detail. Designing an intelligent metal selenides/carbon hybrid assembly is considered to be a very feasible strategy to maximize the potential of metal selenides and carbon materials for electrochemical Na+ storage. Herein, we prepare a hollow double-shell Co-MOF-74-derived CoSe 2 @carbon hybrid in which plenty of ultrafine CoSe 2 nanoparticles are encapsulated within carbon matrix, and such a unique CoSe 2 @carbon hybrid is able to take advantages of both hollow double-shell structure and plum pudding-like structure, which facilitate fast electrochemical kinetics and high tolerance to volumetric strain. As a result, the prepared hollow double-shell CoSe 2 @carbon hybrid exhibits a reversible capacity of 223.4 mAh/g at a very high current density of 10 A/g for Na+ storage, and also holds 92.3 % of capacity retention after 5000 cycles at 2 A/g. This work has provided a useful enlightenment for developing high-efficiency electrode materials in the electrochemical Na+ storage field. [ABSTRACT FROM AUTHOR]