MXene-Enhanced PVDF/Nafion Piezoionic–Electronic Films for High-Performance Self-Polarized Piezoelectric Sensors

Polyvinylidene fluoride (PVDF) is widely used in flexible, self-powered pressure sensors due to its superior piezoelectric properties, although it necessitates the development of a ferroelectric polarized phase for such applications. In recent years, a piezoionic-electronic architecture integrating PVDF with Nafion has emerged, allowing PVDF polarization through mechanical stress alone and thereby streamlining device design and fabrication. To further boost the piezoelectric efficacy of these devices, this work introduces an MXene-based enhancement strategy. Specifically, a trilayered PVDF/Nafion-MXene/PVDF film (referred to as PNMP) was fabricated using hot-pressing, with subsequent mechanical bending to induce self-polarization in the PVDF components. Investigations reveal that the superior piezoelectric properties of the PNMP films originate from the multifunctional role of MXene: aiding Nafion's proton transport while constructing an electron transmission channel, enhancing charge accumulation at the Nafion/PVDF interface, and promoting β-phase formation in PVDF. The fabricated sensor exhibits an extensive pressure-sensing range from 4.7 to 867.0 kPa, a sensitivity of 64.5 mV/kPa, a rapid response of 0.5 ms, an elevated piezoelectric power density of 660 mW/m², and excellent operational durability of 200,000 strikes. The PNMP film's real-world utility was demonstrated via applications like powering LEDs, kinetic energy harvesting, and tracking human movements, highlighting its potential for wearable technologies, energy harvesting, and precise mass sensing. This study provides insightful guidance for advancing next-generation piezoionic-electronic piezoelectric systems.