Room-Temperature Assembled MXene-Based Aerogels for High Mass-Loading Sodium-Ion Storage

Low-temperature assembly of MXene nanosheets into three-dimensional (3D) robust aerogels addresses the crucial stability concern of the nano-building blocks during the fabrication process, which is of key importance for transforming the fascinating properties at the nanoscale into the macroscopic scale for practical applications. Herein, suitable cross-linking agents (amino-propyltriethoxysilane, Mn²⁺, Fe²⁺, Zn²⁺, and Co²⁺) as interfacial mediators to engineer the interlayer interactions are reported to realize the graphene oxide (GO)-assisted assembly of Ti₃C₂T_x MXene aerogel at room temperature. This elaborate aerogel construction not only suppresses the oxidation degradation of Ti₃C₂T_x but also generates porous aerogels with a high Ti₃C₂T_x content (87 wt%) and robustness, thereby guaranteeing the functional accessibility of Ti₃C₂T_x nanosheets and operational reliability as integrated functional materials. In combination with a further sulfur modification, the Ti₃C₂T_x aerogel electrode shows promising electrochemical performances as the freestanding anode for sodium-ion storage. Even at an ultrahigh loading mass of 12.3 mg cm^-2, a pronounced areal capacity of 1.26 mAh cm^-2 at a current density of 0.1 A g^-1 has been achieved, which is of practical significance. This work conceptually suggests a new way to exert the utmost surface functionalities of MXenes in 3D monolithic form and can be an inspiring scaffold to promote the application of MXenes in different areas.