Flexible MXene nanosheet/multiwall carbon nanotube-reinforced poly (vinylidene fluoride-hexafluoropropylene)-polymethyl methacrylate composites for energy storage and EMI shielding.

Developing multifunctional materials that combine high energy storage capability with efficient electromagnetic interference (EMI) shielding remains a major challenge, as these properties often require conflicting structural features. In this work, we developed novel polymer-based nanocomposites (PNCs) using poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polymethyl methacrylate (PMMA) as the polymer matrix, reinforced with multi-walled carbon nanotubes (MWCNTs) and 2D Ti3C2T x MXene. This distinctive combination of MXene-MWCNT forms an interconnected 3D conductive network that not only enhances dielectric constant and electrical conductivity but also maximizes absorption dominated EMI shielding through multiple internal reflections. The formation of an interconnected conductive network facilitated efficient absorption and multiple reflections of incident electromagnetic waves. Interfacial polarization and Maxwell-Wagner-Sillars (MWS) effects elevate the dielectric constant for the 4 wt% nanocomposite film to 91.7 at 100 Hz. The 4 wt% nanocomposite film exhibited a total shielding effectiveness of 40.04 dB in the Ku band and 32.02 dB in the X band. Moreover, an enhanced energy density of 3.46 J cm-3 was achieved owing to improved charge-discharge efficiency. This work demonstrates a scalable route for designing lightweight, flexible PNCs with dual functionality, addressing the current gap between energy storage and EMI shielding applications.