Superior electric displacement and energy storage density in dielectric polymer via inserting thermoplastic polyurethane

Dielectric polymers have been broadly applied in film energy storage capacitors owing to their excellent insulating characteristics. However, low electric displacement (D) and available energy densities (Ue) of existing polymer systems restrict them for miniaturized and integration applications. Herein, thermoplastic polyurethane (TPU) is utilized as the central layer to provide high D, and poly (methyl methacrylate) (PMMA) is used as the coating layer to maintain insulating characteristics. The electric displacement difference (Dmax-Dr) value and Ue values of the all-organic composites were optimized by modifying the relative ratios of the intermediate layer TPU. Notably, the all-organic composites with optimized relative ratio (26.13 vol%) of the TPU layer exhibits the largest Dmax-Dr of 8.27 μC/cm2 at highest breakdown strength of 450 MV/m, which is 89 % higher than that of PMMA at 4.37 μC/cm2, and thus a maximum Ue of 16.23 J/cm3 is obtained, far exceeding the values for advanced polymer and their composites. This strategy provides an effective approach for the development of dielectric polymer with high energy storage capabilities.