Realization of high energy density in an ultra-wide temperature range through engineering of ferroelectric sandwich structures

Thin film dielectrics are the most selected materials for many power electronics owing to their inherent advantages, such as high power density, fast charging-discharging, and long lifetime. Nowadays, additional demands for the film dielectrics are the high performances under harsh operating conditions, e.g. at high temperatures, which is highly favourable to significantly reduce the size and cost of energy devices. Here, we demonstrated that through design and optimization of the film systems with 1 mol% SiO₂-doped BaZr_0.35Ti_0.65O₃ layer sandwiched between two undoped BaZr_0.35Ti_0.65O₃ layers, it is capable to concomitantly enhance breakdown strength and electrical polarization of the systems. The optimized sandwich-structure films yield a greatly improved discharged energy densities of ~130.1 J/cm³ with a high charge-discharge efficiency of ~73.8% at room temperature, as well as retain an ultrahigh discharged energy densities of ~77.8 J/cm³ in the ultra-wide temperature range from −100 to 200 °C. The presented combination of property modulation with structure engineering paves an effective way to meet the increasingly technological challenges and the requirements of modern electrical energy storage applications.