Improved high‐temperature energy storage density at low‐electric field in BOPP/PVDF multilayer films

Abstract Biaxially oriented polypropylene (BOPP) is the most favorable commercial dielectric energy storage film due to its low dielectric loss and high electric breakdown strength. However, its low dielectric constant always leads to relatively low energy storage density. In this study, we propose an efficient strategy to increase the dielectric constant of BOPP films by laminating with high dielectric polyvinylidene fluoride (PVDF). Utilizing the high dielectric constant of PVDF and optimizing its thickness and layers, the high‐temperature energy storage density at low‐electric field is significantly improved. When the thickness of interlayer PVDF is 5 μm and the total number of stacked layers is 7, the BOPP/PVDF multilayer films deliver excellent high‐temperature energy storage performance. The dielectric constant of BOPP/PVDF multilayer films increases to 3.54, 1.74 times higher than pure BOPP films. At a low electric field of 200 kV/mm, the discharged energy storage density of BOPP/PVDF multilayer films increases to 1.02 and 0.99 J/cm 3 at 100 and 125°C. (BOPP ~0.50 and 0.48 J/cm 3 @200 kV/mm). This work provides an efficient way to improve the high‐temperature energy storage density of BOPP films by constructing all‐organic multilayer structure.