3D hierarchical architectures of CoSe2 nanoparticles embedded in rice-derived hard carbon for advanced sodium storage

A low-cost and feasible method to fabricate three-dimensional (3D) hierarchical composites composed of CoSe2 nanoparticles embedded in rice-derived hard carbon (HC) interconnected with carbon nanotubes (CNTs) is devised in this study. The deployment of CoSe2 in the elecrode has provided a very high rate capacity, which is crucial for sodium-ion commercialization. The deployment of HC with CNTs further provides a 3D hierarchical structure effective in shortening the diffusion paths of both electrons and Na+ ions, offering abundance of active sodium storage sites. Consequently, the CoSe2 acted as an active material with the carbonaceous template, a commonly utilized sodium-ion battery anode material, which exhibited a superior reversible capacity of 550 mAh g(-1) at 0.5 A g(-1), outstanding rate performance (451 mAh g(-1) at 20 A g(-1)) and excellent cycling performance (similar to 100% capacity retention over 2500 cycles at 20 A g(-1) after electrochemical stabilization).