Design of the seamless integrated C@NiMn-OH-Ni3S2/Ni foam advanced electrode for supercapacitors

Abstract

Rational design and fabrication of hierarchical structures consisting of multiple components with distinctive features in situ grown on porous Ni foam skeleton is feasible and effective to boost the electrochemical properties of supercapacitors. Herein, a novel hierarchical C@NiMn-OH-Ni3S2/Ni foam hybrid integrated advanced electrode was successfully fabricated via a facile three-step hydrothermal method, involving two hydrothermal reaction to grow NiMn-OH nanoflakes onto Ni3S2 thin film in situ grown on conductive Ni foam and then a glucose carbonization process to cover carbon on NiMn-OH. Benefiting from the synergistic effect of Ni3S2 and NiMn-OH with enhancement of both the electrical and the ionic conductivity, the as-obtained C@NiMn-OH-Ni3S2/Ni foam exhibited an excellent specific capacitance of 2521 F g−1 at a current density of 1 A g−1, and cycle stability increased from 82.4% to 92.1% after coating the carbon layer. Furthermore, an aqueous asymmetric supercapacitor was successfully assembled using C@NiMn-OH-Ni3S2/Ni foam as the positive electrode and activated carbon (AC) as the negative electrode (C@NiMn-OH-Ni3S2/Ni foam//AC), such device delivers a maximum energy density of 45.3 Wh kg−1 at the power density of 1275 W kg−1, and a superior cycling stability (∼94.6% capacity retention after 10,000 cycles).