Intercalation of\nPolyacrylonitrile Nanoparticles in\nTi<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene Layers\nfor Improved Supercapacitance

We report the intercalation of polyacrylonitrile nanoparticles\nin Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene\nlayers through simple sonication. The use of polyacrylonitrile, which\nwas synthesized via radical polymerization, offered dual benefits:\n(1) It increased the interlayer spacing of MXene, thereby exposing\nmore surface area and enhancing ion transport channels during charge\nand discharge cycles, and (2) Integrating MXene with polyacrylonitrile\nenables the creation of a composite with conductive properties, following\npercolation principle. X-ray diffraction analysis showed an increase\nin the c-lattice parameter, indicative of the interlayer spacing,\nfrom 22.31 Å for the pristine MXene to 37.73 Å for the MXene–polyacrylonitrile\ncomposite. The intercalated polyacrylonitrile nanoparticles facilitated\nthe delamination by weakening the interlayer interactions, especially\nduring sonication. Electrochemical assessments revealed significant\nimprovement in the properties of the MXene–polyacrylonitrile\ncomposite compared to the pristine MXene. The assembled asymmetric\ndevice achieved a good specific capacitance of 32.1 F/g, an energy\ndensity of 11.42 W h/kg, and 82.2% capacitance retention after 10,000\ncycles, highlighting the practical potential of the MXene–polyacrylonitrile\ncomposite.