High-energy storage density, responsivity and efficiency, i.e. W_R = 1.07 J/cm³, ξ = 119 J/(kV m²) and η = 92%, were simultaneously obtained in Mn-doped 0.62Bi_0.5Na_0.5TiO₃-0.06BaTiO₃-0.32(Sr_0.7Bi_0.2□_0.1)TiO₃ ergodic relaxor ceramics. Appropriate Mn doping was beneficial to enhance breakdown field strength. Moreover, temperature and different atmosphere-dependent impedance spectroscopy results indicated that oxygen vacancies were the conductivity mechanism for all samples. The valence state of Mn together with the conjugation between Mn ion and oxygen vacancies was confirmed by X-ray photoelectron spectra and electric paramagnetic resonance. The above results indicate that quasi-hysteresis-free loops with high-energy storage performances can be obtained by the induced defect complex. IMPACT STATEMENT High-energy storage density W_R = 1.07 J/cm³, responsivity ξ = 119 J/(kV m²) and efficiency η = 92% were simultaneously obtained in quasi-hysteresis-free ceramics by introducing defect complex. GRAPHICAL ABSTRACT

Fine-grain induced ultrahigh energy storage density and fast discharge speed in novel Bi _0.5 K _0.5 TiO ₃ –Ba(Mg _1/3 Nb _2/3 )O ₃ ceramics via a hot-pressing strategy.

Increasing concern has been focused on the search for ecofriendly dielectric ceramics to meet the extensive demands of pulsed capacitors. Due to the advantages of high-energy storage density, efficiency, and excellent temperature stability, optimization of energy storage performance in dielectric ceramics has been a goal in the past decades. This review summarizes the recently reported progress in energy storage properties of typical perovskite-type lead-free ceramics. The advantages and shortcomings in the various kinds of ceramics are discussed. Finally, future prospects are presented to provide some guidelines for the exploration of new materials.