NiCoO2 nanosheets interlayer network connected in reduced graphene oxide and MXene for high-performance asymmetric supercapacitors

Abstract

The composite electrode materials (rGO/MXene@NiCoO2) have been prepared by tightly wrapping of reduced graphene oxide (rGO) and MXene to NiCoO2 nanosheets. The specific capacitance of rGO/MXene@NiCoO2-5wt% is 1614 F·g−1 at 0.5 A g−1, maintains at 1257.5 F·g−1 when increasing the current density to 10 A·g−1. And the capacitance retention is 77.29% even after 10,000 cycles. It is attributed to the special interlayer network structure of the rGO/MXene@NiCoO2 composite, which promotes more ion intercalation/deintercalation and improves the structure stability. An asymmetric supercapacitor (ASC) is assembled using rGO/MXene@NiCoO2 as the positive electrode and rGO/MXene as the negative electrode, respectively. The maximum energy density is 45.15 Wh·kg−1 and the power density is 394.52 W·kg−1. After 10,000 cycles with current density at 5 A·g−1, the capacity retention rate is 82.69%. These results demonstrate the potential application of rGO/MXene@NiCoO2 composite networks as electrode materials for supercapacitors.