Linear dielectric ceramics for near-zero loss high-capacitance energy storage

Abstract

High energy-density (Wrec) dielectric capacitors have gained a focal point in the field of power electronic systems. In this study, high energy storage density materials with near-zero loss were obtained by constructing different types of defect dipoles in linear dielectric ceramics. Mg2+and Nb5+ are strategically chosen as acceptor/donor ions, effectively replacing Ti4+ within Ca0.5Sr0.5TiO3-based ceramics. The results indicate that under an applied electric field, specific defects such as [MgTi″−VO··] and [NbTi·−Ti3+], can effectively regulate VO·· and electron movement, significantly reducing losses. Furthermore, high-density insulating grain boundaries, reduced VO·· concentrations and diminished carrier mobility contribute to enhanced resistivity, resulting in high Wrec ∼7.62 J/cm3 and η ∼92 % at 640 kV/cm, making it one of the most promising linear dielectrics to date. Notably, Wrec and η remain remarkably stable across a broad range of frequencies (1–500 Hz), temperatures (25–175 °C) and numerous cycles (up to 106). Additionally, finite element software was used to simulate the distribution of dielectric constant, electric potential, and local electric field, further verifying the correlation between microstructure and breakdown resistance. This innovative work provides a sustainable strategy to optimize the energy storage capacity of lead-free ceramics over a wide temperature range through strategic manipulation of defects.