An Eco-Friendly Approach for Fabricating High-Performance Polyvinylidene Fluoride-Co-Chlorotrifluoroethylene Dielectric Film by In-situ Incorporation of Ultralow Carbon Quantum Dots

Polyvinylidene fluoride (PVDF) and its derivatives have long encountered challenges as dielectric materials in pulsed power systems, flexible electronics, and electric vehicle inverter systems due to their inherently high dielectric loss (tanδ), low energy storage density (Ue) and restricted efficiency (η). To address these limitations, we propose a novel and eco-friendly strategy for fabricating high-energy-storage polyvinylidene fluoride-co-chlorotrifluoroethylene (PVDF-CTFE) films through straightforward physical mixing with hydrothermally synthesized carbon quantum dots (CDs). This approach not only ensures uniform in-situ dispersion of CDs within the polymer matrix but also effectively eliminating toxic organic solvents commonly employed in traditional processing. Remarkably, the incorporation of just 0.06 wt% CDs leads to a significant increase in dielectric constant (ɛ' from 7.6 to 10.6) and a substantial enhancement in breakdown strength (Eb from 293 to 443 kV/mm). Consequently, the composite achieves an exceptional Ue of 7.50 J/cm3 with an impressive η of 81.78% at 400 kV/mm, outperforming the performance of pristine PVDF-CTFE (Ue = 2.81 J/cm3, η = 65.26% at 290 kV/mm). These improvements stem from the promoted interfacial polarization and the induced Coulomb blockade effect. What’s more, by acting as electron-trapping sites, the leakage current of the dielectric film is efficiently suppressed, leading to a substantial reduction in tanδ and an increase in η. This study offers a facile, scalable, and eco-friendly route to high-performance dielectric polymers tailored for advanced energy storage applications.