Surfactant-free self-assembled MXene/carbon nanotubes hybrids for high-rate sodium- and potassium-ion storage.

MXenes have been considered as a promising electrode material for Na+ or K+ storage due to their high conductivity, large specific surface area and unique 2D layered structure. However, their tendency to restacking limits the penetration of electrolyte, resulting in poor energy storage capacity. In efforts to overcome this obstacle and take full advantage of Ti 3 C 2 T x MXene, herein, Ti 3 C 2 T x MXene/CNT hybrid has been rationally fabricated as the anode for high-performance sodium- and potassium-ion storage through a surfactant-free assembly strategy assisted by hydrochloric acid (HCl). The HCl-assisted assembly can realize the assembly of Ti 3 C 2 T x MXene and CNT on the nanoscale to make full use of the advantages of CNT as a spacer. Moreover, highly conductive CNT can also provide more diffusion paths for electrons and sodium/potassium ions. Benefiting from the synergistic effect between CNT and Ti 3 C 2 T x flakes, the Ti 3 C 2 T x /CNT hybrid has exhibited excellent electrochemical properties for sodium- and potassium-ion storage. It is worth emphasizing that the Ti 3 C 2 T x /CNT electrode also has superior rate capability, which outperforms that of most reported literatures. This work proposes a new strategy for introducing CNT between MXene layers, which could be expected to be an effective strategy to exert the attracting surface functionality for target applications. [Display omitted] ● Ti 3 C 2 T x /CNT hybrid has been fabricated by a surfactant-free assembly strategy assisted by hydrochloric acid (HCl). ● The HCl-assisted assembly realizes the assembly of Ti 3 C 2 T x and CNT on the nanoscale without contaminating the surface of Ti 3 C 2 T x. ● Ti 3 C 2 T x /CNT hybrids exhibit superior rate capability outperforming that of most reported literatures. [ABSTRACT FROM AUTHOR]