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

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 CoSe2@carbon hybrid in which plenty of ultrafine CoSe2 nanoparticles are encapsulated within carbon matrix, and such a unique CoSe2@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 CoSe2@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.