Sulfur vacancies enriched Nickel-Cobalt sulfides hollow spheres with high performance for All-Solid-State hybrid...

To pursue excellent performance of supercapacitor, an electrode material with designed morphology and tailored intrinsic properties is indeed desired. Herein, nickel-cobalt sulfides hollow spheres decorated with rich sulfur vacancies r-NiCo₂S₄ HSs) are prepared via an anion exchange of Ni-Co coordination polymer spheres, combined with wet chemical reduction. The r-NiCo₂S₄ HSs sample delivers excellent performance as an electrode: it possesses a high specific capacity (763.5C g^-1 at 1 A/g), favorable cyclability (91.40% after 5000 cycles at 10 A/g) and rate capacity (522.68C g^-1 at 15 A/g). Additionally, an all-solid-state hybrid supercapacitor device, assembled with r-NiCo₂S₄ HSs as the positive electrode and N/S co-doped activated carbon nanosheets as the negative electrode, presents an excellent energy density of 50.76 Wh kg^-1 under 800 W kg^-1 and feasible stability. Thus, combining hollow structure with sulfur vacancies could not only increase more active sites and ensure sufficient redox reactions, but also enhance electronic conductivity, facilitate ions / electrons transport and shorten diffusion path, which could be regarded as a promising approach to develop electrode materials with outstanding performance.