High-temperature energy storage performance of PEI/PVDF blends enhanced by Al2O3inorganic layer depositing

In polymer dielectric energy storage, even polymers with high glass transition temperatures suffer significant degradation in energy storage performance as temperature increases, primarily due to a sharp rise in electrical conduction loss. In this study, we employ atomic layer deposition to coat the surface of a PEI/PVDF blend film with an Al2O3inorganic layer to enhance its energy storage performance at high temperatures. The influence of the inorganic layer's thickness on high-temperature energy storage performance is thoroughly analyzed. Experimental results and finite element simulations demonstrate that an ultra-thin Al2O3inorganic layer with the thickness of 50 nm effectively reduces leakage current density and mitigates space charge accumulation within the PEI/PVDF blends, thereby improving the high-temperature energy storage performance of the blends. Notably, under an applied electric field of 500 MV/m at 150 °C, the PEI/PVDF blend film with 50 nm Al2O3layer achieved a discharge energy density of 5.45 J/cm3and a charge-discharge efficiency of 97.75 %.