Rational design of heterostructured bimetallic sulfides (CoS2/NC@VS4) with VS4 nanodots decorated on CoS2 dodecahedron for high-performance sodium and potassium ion batteries.

Developing electrode materials with desirable electrochemical properties for sodium and potassium ion batteries remains a tremendous challenge. Herein, hetero-structured hybrids with VS4 nanodots decorated on CoS2/NC dodecahedron (CoS2/NC@VS4) have been successfully synthesized through employing a cobalt-based imidazolate framework (ZIF-67) as a template to prepare CoS2/NC inner core. Then VS4 nanodots was then grown on the surface of CoS2/NC by hydrothermal method to construct a heterostructure. This heterogeneous structure facilitates full contact with the electrolytes and shortens electrons and ions diffusion distance. Besides, the nitrogen-doped carbon framework derived from ZIF-67 promotes electron transport and gives a reliable shield to buffer the volume swelling during discharge and charge processes. Driving by the synergistic effect of bimetallic sulfides and the multiple valence states vanadium sulfide, CoS2/NC@VS4 exhibits outstanding rate capability and stable cycle performance as the anode for SIBs and PIBs, including a specific capacity of 307 mAh g-1 at the current density of 1.0 A g-1 after 700 cycles for SIBs and a capacity of 291.54 mAh g-1 at the current density of 1.0 A g-1 after 430 cycles in PIBs.