Construction of sulfur vacancies enriched hollow zinc cobalt bimetallic sulfides for high-performance supercapacitors

Abstract

Designing bimetallic sulfide materials with well-defined nanostructure and high energy density is indeed desirable for high-performance supercapacitors. Here, a hollow zinc cobalt sulfide (Zn x Co 3−x S 4 ) dodecahedron with plentiful sulfur vacancies is synthesized through a co-precipitation approach followed by a solvothermal vulcanization treatment. The tailored hollow structure can effectively accelerate the charge transport and facilitate the diffusion of OH - , whereas the sulfur vacancies significantly increase the amount of contact active sites and enhance the electronic conductivity. Both of the features can simultaneously promote the capacitance performance of Zn x Co 3−x S 4 for supercapacitors, where the most-performing Zn 0.3 Co 2.7 S 4 electrode, achieves a high specific capacitance of 545.9 C g −1 in 3 M KOH electrolyte at the current density of 1 A g −1 and excellent long-term durability of 84.7% capacity retention after 1000 cycles. Particularly, the assembled aqueous hybrid supercapacitors delivers high energy density and superior cyclic stability. This study demonstrates a rational design of well-controlled bimetallic sulfides with outstanding electrochemical performance for energy storage devices. • The hollow Zn x Co 3−x S 4 was synthesized through a co-precipitation followed by a solvothermal vulcanization treatment. • The S-vacancies and hollow structure simultaneously enhanced the capacitance performance of Zn x Co 3−x S 4 . • The assembled hybrid supercapacitor delivered a competitive energy density.