Achieving Ultrahigh Energy Storage Density for BaTiO-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 () 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 BaTiO-based system, recoverable energy storage densities exceeding 6 J/cm remain exceedingly rare, especially under moderate electric fields (300 kV/cm < < 500 kV/cm). In this paper, based on the relationship of energy storage among dielectric permittivity (ε) and electric field (), we constructed a superparaelectric state near room temperature and improved ε by introducing centrosymmetric BiScO into a high ε matrix (BaSrCaSnTiO). Ultimately, this strategy enables the realization of an ultrahigh energy storage density of 6.95 J/cm 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.