Interface and structure engineering of bimetallic selenides toward high-performance sodium-ion half/full batteries

Transition metal selenides are widely explored as promising anodes for sodium-ion batteries (SIBs) because of their high theoretical capacity. However, rapid capacity decay caused by the structural collapse during cycling greatly hampers their applications in SIBs. Herein, we report a synergistic engineering of interface and structure to synthesize CoSe2-MoSe2 yolk-shell spheres. Such exquisite boundary architecture is beneficial to improving the electrochemical kinetics. Meanwhile, the yolk-shell structure further modulates the mechanical stress for stable performance. As expected, the CoSe2-MoSe2 yolk-shell spheres deliver a high capacity of 466 mAh g(-1) after 1000 cycles at the ultrahigh rate of 10 A g(-1). The sodium storage mechanism of the CoSe2-MoSe2 yolk-shell spheres is investigated by kinetic tests and first-principles calculations. Coupled with a Na3V2(PO4)(2)O2F cathode, the as-constructed full batteries show a remarkable energy density of 133 Wh kg(-1), promoting the development of high-energy density energy storage devices.

Automated summary

The CoSe2-MoSe2 yolk-shell spheres synthesized through synergistic engineering of interface and structure exhibit high capacity and stable performance in sodium-ion batteries, showing great potential for high-energy density energy storage devices.