Hierarchical Ti3CNTx/CNF composite films with expanded interlayer spacing for high-performance flexible micro-supercapacitors

The practical energy storage application of two-dimensional (2D) MXenes is fundamentally constrained by the restacking of nanosheets, which severely impedes ion transport kinetics. Here, we demonstrate a strategy to mitigate this issue by intercalating one-dimensional cellulose nanofibers (CNFs) into 2D Ti3CNTx MXene films, creating a hierarchical composite architecture. The CNF spacers effectively expand the interlayer spacing of the Ti3CNTx from 1.326 to 1.448 nm, significantly increasing the specific surface area from 43.0 to 160.1 m2 g−1. This structurally engineered film, when used as an electrode, exhibits a high specific capacitance of 441.6 F g−1. Flexible micro-supercapacitors fabricated from this composite deliver an impressive energy density of 6.2 mWh g−1 and demonstrate exceptional mechanical robustness. This work provides a scalable approach to engineering the nano-architecture of 2D materials for advanced flexible energy′ storage devices.