Achieving Ultrahigh Energy Storage Density for BaTiO3-Based Ceramics under Moderate Electric Fields via Regulating Dielectric Permittivity

The development of lead-free relaxor ferroelectric ceramics with high energy storage density has emerged as a critical area, driven by the increasing demand for advanced energy storage capacitors and high-power density devices. Conventional approaches to enhance energy-storage performance in lead-free dielectric ceramics typically rely on achieving ultrahigh breakdown field strength (Eb) or employing complex multicomponent composite strategies. However, the requirement for high electric fields hinders the miniaturization and integration of the devices. Furthermore, despite extensive research on the classic BaTiO3-based system, recoverable energy storage densities exceeding 6 J/cm3 remain exceedingly rare, especially under moderate electric fields (300 kV/cm < E < 500 kV/cm). In this paper, based on the relationship of energy storage among dielectric permittivity (εr) and electric field (Wcal=12ε0εrE2), we constructed a superparaelectric state near room temperature and improved εr by introducing centrosymmetric BiScO3 into a high εr matrix (Ba0.65Sr0.3Ca0.05Sn0.02Ti0.08O3). Ultimately, this strategy enables the realization of an ultrahigh energy storage density of 6.95 J/cm3 and a high energy efficiency of 86.17% under moderate electric fields (500 kV/cm). These findings provide a practical and innovative pathway for developing high-performance energy storage capacitors, advancing the potential for lead-free dielectric ceramics in next-generation energy storage technologies.