Significantly enhanced ultrathin NiCo-based MOF nanosheet electrodes hybrided with Ti3C2Tx MXene for high performance asymmetric supercapacitors

Abstract

In situ synthesis of NiCo based metal-organic framework (MOF) nanosheets and the exfoliation of Ti3C2Tx into isolated nanosheets (MXene), called, NiCo-MOF/Ti3C2Tx hybrid nanosheets, are simultaneously achieved by a facile ultrasonic method. This method can effectively avoid the oxidation and restacking of Ti3C2Tx nanosheets, and also make them uniformly disperse on the surface of NiCo-MOF. The formed NiCo-MOF/Ti3C2Tx hybrid nanosheets achieve a high specific capacitance of 815.2 A g-1 at 1 A g-1. The practical asymmetric supercapacitor (ASC) is fabricated using activated carbon and NiCo-MOF/Ti3C2Tx hybrid nanosheets. The ASC device achieves an energy density of 39.5 Wh kg-1 at a power density of 562.5 W kg-1, and also demonstrates a suitable cycling stability with 82.3 % of capacitance retention after 10000 continuous cycles at 5 Ag-1. The enhanced electrochemical property of NiCo-MOF/Ti3C2Tx is attributed to the nanosheet-like and mesoporous structure, high electronic conductivity, and synergistic effect of hybrid electroactive components.