The influence of organic montmorillonite on the breakdown strength and energy density of poly(vinylidene fluoride)-based nanocomposites

Capacitor films with superior transmittance, flexibility, and high performance have attracted considerable attentions in the field of advanced energy storage devices. Nevertheless, the energy density is always increased at the expense of the dielectric constant or breakdown strength on one side. Therefore, based on the above stated issues, energy storage films with good optical transmission and breakdown resistance were prepared by combining a small amount of lamellar organic montmorillonite (OMMT) with poly(vinylidene fluoride) (PVDF) substrates by a simple but effective solution blending method. The addition of OMMT effectively converts the crystalline structure of the PVDF matrix, making it more favorable for dielectric energy storage films, and the polymer-based nano energy storage films exhibit an optical transmission of approximately 90% at 800 nm. More importantly, the presence of OMMT, a unique lamellar structure, effectively hinders the growth of electrical trees within the polymer composite, thereby improving the overall breakdown strength of the composite. Ultimately, at 0.6 wt% filler content, the PVDF/OMMT nanocomposite exhibited a breakdown strength of 460 MV/m and a discharge energy density of 7.26 J/cm(3) as well as an energy efficiency of 69%.