Microcapacitance-Enhanced Nanostructured Polyvinylidene Fluoride Composites for Enhanced Energy Storage and Flexible Piezoelectric Sensing Applications

This article describes a significant enhancement of the piezoelectric properties of poly(vinylidene fluoride) (PVDF) through interfacial engineering and a magnetically oriented structural design. Reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry were used to graft three polyionic liquids (PILs) with different alkyl chain lengths onto the surface of MXene. This successfully suppressed MXene’s self-stacking problem and enhanced its compatibility with PVDF. Next, Fe₃O₄ nanoparticles were introduced to impart a magnetic response, followed by a solution-melt synergistic "piezo-folding cycle” process to induce the formation of the β-phase. In the experiments, this resulted in a piezoelectric coefficient (d₃₃) of 45 pC/N, a 15-fold increase compared to pure PVDF (∼3 pC/N). The resulting piezoelectric nanogenerator (PENG) produces an output current of 0.2 mA at a 120 N load and exhibits a sensitivity of 6.67 µV/N. This work demonstrates the effectiveness of using MXene to induce piezoelectricity in PVDF.