Enhanced Energy-Storage Performance in Ba0.85Ca0.15Zr0.1Ti0.9O3 Ceramics via Bi2/3(Al0.5Ta0.5)O3 Modification

As a lead-free material located at the morphotropic phase boundary, Ba0.85Ca0.15Zr0.1Ti0.9O3 possesses an exceptionally high polarization potential, making it an attractive candidate matrix for high-performance energy storage ceramics. However, its practical application is largely limited by a low breakdown electric field (Eb) and a large remanent polarization (Pr). In this work, an A-site-deficient, nonstoichiometric Bi2/3(Al0.5Ta0.5)O3 component was employed to construct (1 − x) Ba0.85Ca0.15Zr0.1Ti0.9O3-xBi2/3(Al0.5Ta0.5)O3 (BCZT-xBAT, x = 0.02–0.12) solid solutions, which were then fabricated using a conventional solid-state reaction. XRD Rietveld refinement results confirmed the coexistence of tetragonal (P4mm) and cubic (Pm3m) phases in BCZT-xBAT (x = 0.02–0.12) at room temperature, and with increasing BAT content, a gradual increase in the Pm3m fraction, accompanied by a corresponding decrease in the P4mm one, was observed, along with enhanced relaxor behavior at low temperatures. Meanwhile, incorporating an appropriate amount of BAT, the BCZT-0.10BAT exhibits a well-developed grain-boundary network and dense microstructure, impeding the formation and propagation of localized conductive paths, thus enhancing Eb. These combined structural modifications are beneficial to energy-storage performance. Consequently, the BCZT-0.10BAT ceramics achieved optimal energy-storage performance at 200 kV/cm, with a recoverable energy-storage density of 1.042 J/cm3 and an ultrahigh efficiency of 98.36%, while exhibiting excellent stability against variations in frequency and temperature. These results demonstrate that BAT serves as an effective component for enhancing the energy-storage performance of BCZT ceramics, making the material a promising candidate for pulse-power capacitor applications, especially under low-to-moderate electric fields.