Synthesis and\nFabrication of Metal Cation Intercalation\nin Multilayered Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> Composite CNF Electrode for Asymmetric Coin Cell Supercapacitors

Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> has attracted\nconsiderable attention from researchers in energy storage due to its\nunique structure and beneficial surface functional group characteristics.\nRecent studies have focused extensively on developing Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> composites to create\npotential electrode materials for energy storage applications. Carbon\nnanofiber is often combined with Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> to produce high-performance functional nanocomposites,\neffectively harnessing the unique properties of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> nanosheets while ensuring exceptional\nelectrochemical behavior. This work employs an ultrasonication method\nto prepare a Na–Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>/CNF electrode. Establishing a stable interlayer structure\nbetween Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> nanosheets\nand cationic metal intercalation materials is crucial for expanding\nthe interlayer spacing of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> and creating multidirectional stable ion transport\nchannels. Consequently, this process exposes more active sites that\nare accessible to ions. At a current density of 1 A g<sup>–1</sup>, the resulting Na–Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>/CNF demonstrates an impressive specific capacitance\nof 680.2 F g<sup>–1</sup>. Notably, the asymmetric supercapacitor\nassembled with Na–Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>/CNF as the positive electrode and activated carbon\nas the negative electrode exhibits remarkable cyclic retention of\n83.1% and the Coulombic efficiency of 90.5% after 10,000 cycles at\n10 A g<sup>–1</sup>, a wide voltage window of 1.5 V, a high\nenergy density of 102.5 W h kg<sup>–1</sup>, and a power density\nof 2963.7 W kg<sup>–1</sup>. The fabricated coin cell ASC devices,\nwhich include glowing red light-emitting diodes, were demonstrated\nin practical applications. The optimization strategy for developing\nNa–Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>/CNF provides essential technical support for integrating Na–Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>/CNF into the next\ngeneration of portable and adaptable wearable electrochemical energy\nstorage devices.