Ni3S4 nanoparticle decorated Mn doped Co(OH)2 nanosheets as electrodes of hybrid supercapacitors with high energy density and long-term cycle stability.

Due to their outstanding electrochemical properties, transition metal sulfides and hydroxides are often used as high-performance electrode materials for supercapacitors. The Mn-doped Co(OH) 2 /Ni 3 S 4 electrode material in this study, due to the synergistic reaction mechanism among Co(OH) 2 and Ni 3 S 4 and the increased active sites by the addition of Mn, the Mn-Co(OH) 2 /Ni 3 S 4 exhibits excellent electrochemical property. The electrochemical performance of the Mn-Co(OH) 2 /Ni 3 S 4 hybrid electrode was measured in an electrode cell made of 2 M KOH solution, showing a superior specific capacitance of 1107.0 C g−1 at 0.5 A g−1, in addition to the excellent capacity retention rate at 10 A g−1 is 72.7 % of that at 1 A g−1. The performance of the hybrid supercapacitor (HSC) assembled with Mn-Co(OH) 2 /Ni 3 S 4 compound and activated carbon (AC) was measured under the same electrolyte conditions, anwell-specificific capacity (157.2 F g−1 at 0.5 A g−1) was achieved, along with superior long-term stable charge/discharge capability (88.9 % of the original specific capacity after 35,000 cycles at 8 A g−1). Meanwhile, the most practical application is when the power density of 410.4 W kg−1, the assembled HSC device has an energy storage capacity of 58.8 W h kg−1, revealing that the developed Mn-Co(OH) 2 /Ni 3 S 4 has great application potential for supercapacitors in the future. [Display omitted] • Mn-Co(OH) 2 /Ni 3 S 4 was synthesized via co-precipitation, and hydrothermal processes. • Mn-Co(OH) 2 /Ni 3 S 4 electrode achieves a large specific capacity of 1107 C g−1 at 0.5 A g−1. • The specific capacity maintains 72.7 % when the current density is changed from 1 A g−1 to 10 A g−1. • Mn-Co(OH) 2 /Ni 3 S 4 //AC HSC obtains an energy density of 58.8 Wh kg−1 at a power density of 410.4 W kg−1. • The capacitance of the Mn-Co(OH) 2 /Ni 3 S 4 //AC maintains ∼89.0 % after 35,000 cycles. [ABSTRACT FROM AUTHOR]