Self-assembly of Alternating Stacked 2D/2D Ti₃C₂T_x MXene/ZnMnNi LDH van der Waals Heterostructures with Ultrahigh Supercapacitive Performance

In the field of energy storage, layered double hydroxides (LDHs) have aroused researchers’ extensive attentions because of their low cost, high theoretical specific capacitance (SC), and adjustable interlayer structure. Notably, the appearance of single-layer or few-layer LDHs nanosheets has addressed the puzzle of large wall thickness and shows a large specific surface area which produces more active sites. However, the cyclic stability of the LDHs nanosheets has been hindered, which result from their poor conductivity, weak structural stability and natural stacking, so the usefulness of them is limited in practice. In this work, exfoliated two-dimensional (2D) MXene (F-MXene)/exfoliated 2D ZnMnNi LDH (F-ZnMnNi LDH) van der Waals heterostructures were successfully fabricated by using electrostatic self-assembly between negatively titanium carbide F-MXene nanosheets and positively charged F-ZnMnNi LDH nanosheets. The as-prepared 2D/2D van der Waals heterostructures integrate the advantages of F-MXene and F-ZnMnNi LDH, including outstanding electron conductivity, stable structure, and superior redox activity. Accordingly, the as-prepared sample exhibits ultrahigh SC of 2065 F/g at a scan rate of 5 mV/s and remarkable cycling stability with capacitance retention of 99.8% after 100 000 cycles at a current density of 1 A/g.