Architecturally Robust Graphene-Encapsulated MXene Ti₂CT_<i>x</i>@Polyaniline Composite for High-Performance Pouch-Type Asymmetric Supercapacitor

Abstract

A harmonized three-component composite system which preserves the characteristics of individual components is of interest in the field of energy storage. Here, we present a graphene-encapsulated MXene Ti2CTx@polyaniline composite (GMP) material realized in a systematically stable configuration with different ternary nanomaterials for supercapacitor electrodes. Due to the different ζ-potentials in a high-pH solution, chemically converted graphene (negatively charged) is thoroughly unfolded to allow full encapsulation, but the MXene Ti2CTx@polyaniline composite with a low positive ζ-potential is easily attracted toward a counter-charged substance. The obtained GMP electrode exhibits improved cycling stability and better electrochemical performance owing to the use of mechanically robust and chemically inert graphene and the densely intercalated conductive polyaniline between the multilayer MXenes. The GMP electrode has a high gravimetric capacitance of 635 F g–1 (volumetric capacitance of 1143 F cm–3) at a current density of 1 A g–1 with excellent cycling stability of 97.54% after 10 000 cycles. Furthermore, the asymmetric pouch-type supercapacitor assembled using the GMP as a positive electrode and graphene as a negative electrode yields a high energy density of 42.3 Wh kg–1 at a power density of 950 W kg–1 and remarkable cycling stability (94.25% after 10 000 cycles at 10 A g–1).