A Highly Conductive and Supercapacitive MXene/N-CNT Electrode Material Derived from a MXene-Co-Melamine Precursor

Abstract

MXene is a two-dimensional nanostructured transition metal carbon/nitride and carbon nanotubes (CNTs) are a one-dimensional graphitized carbon material, which are widely exploited for their large specific surface and excellent electrical conductivity, but the easy aggregation limits their performance. In this work, a MXene-Co-melamine precursor is elaborately assembled by coordination bonds and a highly dispersed MXene/N-CNT composite material is ultimately constructed via a segmental pyrolysis of the MXene-Co-melamine precursor. This strategy synchronously relieves the self-restacking problem of MXene and N-CNTs. The optimal 0.60-MXene/N-CNT is composed of abundant and homogeneous CNTs with a high nitrogen dosage of 5.879 wt %. And it has a large BJH adsorption average pore size of 11.5 nm, a high microporous–mesoporous distribution of 1.94% micropores and 61.67% mesopores, and a well-matched hierarchical pore structure. Due to the orderly assembled porous structure of MXene and N-CNTs, the 0.60-MXene/N-CNT exhibits a high specific capacitance of 167.2 F g–1 at 0.5 A g–1. The assembled 0.60-MXene/N-CNT//AC asymmetric supercapacitor maintains a high capacitance retention of 73.2% after 10,000 cycles at 5 A g–1 current density and a high Coulomb efficiency of 97.5%. Its energy density also can reach 12.1 Wh kg–1 at a power density of 195.4 W kg–1.