Realizing ultrahigh energy-storage density in Ca0.5Sr0.5TiO3-based linear ceramics over broad temperature range

In the realm of energy storage, there is an exigent need for dielectric materials that exhibit high energy storage density (Wrec) and efficiency (η) over wide temperature ranges. Linear dielectrics exhibit superior breakdown strength (Eb) compared to ferroelectrics, yet their utility is restricted by low polarization. Here, an ultrahigh Wrec up to 7.92 J/cm3 and η ≈ 94.3% are realized in (Ca0.5Sr0.5)1-1.5xSmxTiO3 ceramic with ultrafast discharge time (t0.9 = 20 ns) which is one of the best energy storage performances recorded linear ceramics. By employing the charge balance method, the production of oxygen vacancies (VO··) can be prevented, leading to improved insulation. The creation of A-site vacancies serves to enhance the breakdown field strength. Furthermore, the incorporation of Sm3+ effectively limits the thermal activation of oxygen vacancies at elevated temperatures, ultimately resulting in an increase in bulk resistivity. The results also unveil the outstanding stability across a wide range of temperatures (20 °C–140 °C) and frequencies (1 Hz–500 Hz). Consequently, this study provides significant insights into enhancing Eb and attaining high-energy storage capacitors.