Exfoliating Ti3AlC2 MAX into Ti3C2Tz MXene: A Powerful Strategy to Enhance High-Voltage Dielectric Performance of Percolation-Based PVDF Nanodielectrics

Abstract

All-solid-state polymer dielectrics benefit from a superior voltage window and conveniently circumvent fire hazards associated with liquid electrolytes. Nevertheless, their future competitiveness with alternative energy storage technologies requires a significant enhancement in their energy density. The addition of conductive 2D MXene particles is a promising strategy for creating percolation-based nanodielectrics with improved dielectric response. However, a full understanding of the nanodielectric production – microstructure – dielectric performance correlations is crucial. Therefore, this research considered Ti₃AlC₂ MAX phase and Ti₃C₂T_z MXene as electrically conductive ceramic fillers in polyvinylidene fluoride (PVDF). Microstructural characterization of both nanodielectrics demonstrated excellent filler dispersion. Additionally, the exfoliation of Ti₃AlC₂ brought forth extensive alignment and interface accessibility, synergistically activating a pronounced interfacial polarization and nanocapacitor mechanism that enhanced the energy density of PVDF by a factor 100 to 3.1 Wh kg⁻¹@0.1 Hz at 22.9 vol% MXene filler. The stellar increase in the PVDF energy density occurred for a broad MXene filler loading range owing to the unique 2D morphology of MXenes, whereas the addition of Ti₃AlC₂ fillers only caused a detrimental reduction. Hence, this study buttressed the importance to exfoliate the parental MAX phase into multi-layered MXene as a decisive strategy for boosting nanodielectric performance.