A High-Biocompatibility, Anticounterfeiting, Flexible Dielectric Energy Storage Film Enabled by Multiple Structure Optimization Strategies

The development of wearable polymer dielectric capacitors is hindered by the trade-off between dielectric constant and breakdown strength, along with insufficient inherent biocompatibility. Herein, we design a sandwich-structured composite comprising a SiO2@spiropyran@PVDF core-shell interlayer, a crosslinked PVDF outer layer, and a PANI-blended PVDF outer layer. This architecture enables synergistic interfacial polarization amplification, leakage suppression, and photochromic fluorescence for anticounterfeiting. The composite achieves a dielectric constant of 34.2 with low loss, a discharged energy density of 9.07 J cm-3 with an efficiency of 73.8%, and a large switchable polarization difference of 4.78 μC cm-2. It also retains the flexibility of pure PVDF and exhibits excellent biocompatibility, as evidenced by a cell viability of 94.5% after 120 h incubation, comparable to the negative control.