Metal-organic framework derived hollow rod-like NiCoMn ternary metal sulfide for high-performance asymmetric supercapacitors

In this work, metal-organic frameworks (MOFs) derived hollow rod-like NiCoMn ternary metal sulfides nanosheets are successfully synthesized by the etching/ion-exchange reaction and additional sulfurization. The formed hollow structure exhibits a unique hierarchical architecture constructed by NiCoMn-S nanosheets and internal porous channels, which is beneficial for the penetration of electrolyte and the electron/ion transportation. The as-prepared NiCoMn-S nanosheets present significant synergy among transition metal ions, which contributes to enhanced electrochemical performances. Owing to structural and compositional advantages, the optimized NiCoMn-S nanosheets show a superior specific capacitance (2098.2 F g(-1) at 1 A g(-1)) than corresponding hydroxide precursor (NiCoMn-OH) and other controlled sulfides with different ratio of Ni/Co/Mn. The as-assembled asymmetric supercapacitor (ASC) using NiCoMn-S nanomaterials as positive electrode and activated carbon (AC) as negative electrode delivers a high specific capacitance of 124.5 F g(-1) at 1 A g(-1) and a maximum energy density of 50.0 Wh kg(-1) at 850.0 W kg(-1) as well as excellent capacitance retention (73.6% after 6000 cycles). Therefore, the prepared NiCoMn-S electrode materials have a broad application prospect in high-performance supercapacitors.