Defect enables advanced energy storage in ultrahigh-temperature dielectric capacitors

Dielectric capacitors featured with ultrahigh power density and ultrafast charge/discharge speeds are highly valued in advanced electronic and electrical power systems. In pursuit of dielectric capacitor development in various scenarios, high energy storage density and efficiency are the important issues, especially in extreme high-temperature environments. Unfortunately, the existing dielectric capacitors still face the attenuation of polarization and the deterioration of insulation as the temperature increases and accompaning a sharply deteriorated energy performance and lifetime under extreme temperatures. Here, we propose a controlled process strategy to design the Ti-O defect dipoles in BaSn_0.15Ti_0.85O₃ relaxor ferroelectrics by tuning the adatom diffusion/growth kinetic energy. Our results demonstrate that the additional chemical internal-stress induced by the interaction of defects and host lattice increases the phase transition temperature up to ∼800 °C. Meanwhile, governing defect density in relaxor ferroelectrics can function as a knob to tune the charge-carrier transport barrier and dipole switching behaviors to synergistically enhance breakdown strength and reduce hysteresis loss. The defect dipole design not only enables the energy storage density W_re go up to 140.60 J·cm⁻³ with an efficiency of 78 % at room temperature, but also can realize the excellent thermal stability over a wide temperature range from −100 °C to 400 °C with W_re of 82.31 J·cm⁻³ and antifatigue properties after 10⁶ cycles. Our work opens up a practical avenue to the development of advanced high-temperature capacitors tailored for cutting-edge high-power devices serving in extreme environments.