Enhancing Energy Storage and Electrode Scalability in Au/PVDF Composite Films Through Al2O3 Interface Engineering

Interfacial effects and surface defects play a significant role in determining the properties of dielectric films. In this study, Au/PVDF films were fabricated using polyvinylidene fluoride (PVDF) as the polymer matrix and gold (Au) nanoparticles as fillers. Additionally, Al₂O₃–Au/PVDF films (AO-Au/PVDF) were produced by depositing a layer of aluminum oxide (Al₂O₃) onto the film surfaces through magnetron sputtering. The interfacial interactions between the Al₂O₃ layer and the Au/PVDF film, along with the role of Al₂O₃ in mitigating surface defects, were investigated concerning dielectric properties, real-time breakdown morphology on electrode surfaces, breakdown strength, and energy storage density at electrode sizes of 1 mm, 2 mm, 4 mm, and 8 mm. Compared to Au/PVDF films, AO-Au/PVDF films demonstrated relatively fewer breakdown points on their electrode surfaces. The breakdown strength improved by 7.7%, 8.8%, 6.3%, and 8.2% for the respective electrode sizes; consequently, this enhancement resulted in an increase in energy storage density. The incorporation of an Al₂O₃ layer effectively reduced surface defects within the film while decreasing the occurrence of partial breakdown points. This improvement contributed to enhanced breakdown strength and energy storage density while facilitating compatibility with larger-sized electrodes.