Tough and Fatigue Resistant Cellulose Nanocrystal Stitched Ti₃ C₂ T_x MXene Films

Ti₃ C₂ T_x MXene (or "MXene" for simplicity) has gained noteworthy attention for its metal-like electrical conductivity and high electrochemical capacitance-a unique blend of properties attractive toward a wide range of applications such as energy storage, healthcare monitoring, and electromagnetic interference shielding. However, processing MXene architectures using conventional methods often deals with the presence of defects, voids, and isotropic flake arrangements, resulting in a trade-off in properties. Here, a sequential bridging (SB) strategy is reported to fabricate dense, freestanding MXene films of interconnected flakes with minimal defects, significantly enhancing its mechanical properties, specifically tensile strength (≈285 MPa) and breaking energy (≈16.1 MJ m^-3 ), while retaining substantial values of electrical conductivity (≈3050 S cm^-1 ) and electrochemical capacitance (≈920 F cm^-3 ). This SB method first involves forming a cellulose nanocrystal-stitched MXene framework, followed by infiltration with structure-densifying calcium cations (Ca²⁺ ), resulting in tough and fatigue resistant films with anisotropic, evenly spaced, and strongly interconnected flakes - properties essential for developing high-performance energy-storage devices. It is anticipated that the knowledge gained in this work will be extended toward improving the robustness and retaining the electronic properties of 2D nanomaterial-based macroarchitectures.