High-performance all-solid-state asymmetrical supercapacitors based on petal-like NiCo 2 S 4 /Polyaniline nanosheets

The synthesis of NiCo2S4 as electroactive material has been well reported, however, fabricating a NiCo2S4 electrode with excellent electrochemical performance at high current density remains a challenge. Herein, we developed a supercapacitor electrode comprising petal-like NiCo2S4/Polyaniline (PANI) nanosheets via a simple hydrothermal route coupled with a chemical oxidative polymerization. Benefiting from the integration of PANI, which greatly enhance ion-accessibility and lead to more efficient charge transportation, the resultant NiCo2S4/PANI electrode exhibited a high specific capacitance of 1879 F g−1 at a current density of 1 A g−1 and an excellent rate capability of 72% at 20 A g−1, after 2000 cycles, only 8.9% loss of initial capacitance at a high charge/discharge current density of 8 A g−1. Moreover, a flexible all-solid-state asymmetric supercapacitor was successfully assembled using NiCo2S4/PANI as the positive electrode and activated carbon (AC) as the negative electrode, the assembled device exhibits a superior energy density of 54.06 Wh kg−1 at 0.79 kW kg−1, outstanding power density of 27.1 kW kg−1 at 15.9 Wh kg−1, which significantly transcending those of most previously reported. This study shows that the prepared NiCo2S4/PANI electrode offers great potential in energy storage device applications.