Controllable synthesis of cross-linked CoAl-LDH/NiCo2S4 sheets for high performance asymmetric supercapacitors

Abstract Cross-linked CoAl-LDH/NiCo2S4 sheets hybrids hold a promising electrochemical material for high-performance supercapacitors. In this paper, we report a simple strategy for fabricating flocculent NiCo2S4 decorated on CoAl-LDH nanosheets to form integrated hybrid architectures (CoAl-LDH/NiCo2S4) via hydrothermal and electrodeposition method. Benefiting from the integrated structures of CoAl-LDH/NiCo2S4 sheets, which can provide a short diffusion path for electrolyte ions and a high utilization rate for electrode materials, the resultant CoAl-LDH/NiCo2S4 hybrid electrode exhibits a high specific capacity of 1.52 C cm−2（760 C g−1）at the current density of 2 mA cm−2, a superior rate capability of 78.94% when the current density is increased to 10 mA cm−2, much higher than the simple CoAl-LDH nanosheets electrode. An asymmetric supercapacitor fabricated using the cross-linked CoAl-LDH/NiCo2S4 hybrids as the positive electrode and 3D reduced graphene oxide (rGO) aerogel as negative electrode shows a high energy density of 44.67 W h kg−1 at a power density of 0.4 kW kg−1, and an energy density of 24.4 W h kg−1 can be retained even at a high power density of 4.0 kW kg−1.