Facile self-assembly of sandwich-like MXene/graphene oxide/nickel–manganese layered double hydroxide nanocomposite for high performance supercapacitor

The sandwich-like MXene/graphene oxide/nickel–manganese layered double hydroxide (MGL) were self-assembled by the conductive interface of MXene, graphene oxide (GO) and intercalated layered double hydroxide (LDH), which was designed to a unique nanostructure with more exposed active sites. Benefiting from heterostructure, MXene stacking problem is efficiently prevented. Furthermore, the suppression of LDH morphological collapse highly promotes the specific capacity of LDH. GO, as a thin layer, covers the surface of the compound with an elaborate structure to accelerate charge transfer and increase electron density of materials. The synergistic effect of different composites enhances exposed active sites to a great extent and electrical activity of electrodes in redox reaction. As cathode material, the MGL shows excellent specific capacity of 241.9 mAh g−1 and remarkable cycle stability of ∼90.9% at a current density of 1 A g−1 caused by multi-valence (Mn, Ni) hydroxide and stable carbon materials. The combination of the surface GO and the conductivity of the substrate MXene enhances the available electrons on the hydroxide. Notably, the asymmetric supercapacitor achieved the impressive ∼94.7% retention of primal capacity after 4,000 cycles and specific energy of 55.3 Wh kg−1 at the specific power of 800 W kg−1.