Cu-doped NiCo2S4/Kochia biomass porous carbon electrode material with high performance for hybrid supercapacitors

Abstract

The suitable strategy combining metal doping and the introduction of porous carbon as a conductive substrate is proposed to address the shortcomings of the nickel‑cobalt sulfide (NiCo2S4) electrode material under development for supercapacitor energy storage. The multiplicative performance and cycle stability of NiCo2S4 have been significantly enhanced by the low cost and outstanding conductivity of copper (Cu) as a dopant. As well, the incorporation of Kochia biomass porous carbon (KAC-5), which has made it feasible to recycle waste biomass, into Cu-doped NiCo2S4 has effectively addressed the structural stability and electrochemical performance issues of NiCo2S4 electrode. The results showed that the introduction of Cu effectively optimizes the electrochemical properties by modifying the electronic state of the NiCo2S4 electrode to achieve the desired outcome. A composite material (Cu-NCS-10) was produced by adding KAC-5, due to the effects of KAC-5 on its geometry and electronic state, as well as its unique surface and structural characteristics, Cu-NCS-10 exhibits highly desirable energy storage. In comparison to the NiCo2S4 electrode, the Cu-NCS-10 electrode enhances specific capacity at 1 A·g−1 from 627C·g−1 to 754C·g−1, rate capability increased from 78.2 % to 88.1 % (1 A·g−1 to 10 A·g−1), and capacity retention after 5000 cycles from 75.9 % to 83.7 %. The electrochemical performance of the hybrid supercapacitor Cu-NCS-10||KAC-5 showed a wider voltage window, an energy density of up to 46.3 Wh·kg−1 at a power density of 775 W·kg−1, and maintenance of 80.9 % after 5000 cycles.