Delayed Polarization Saturation Induced Superior Energy Storage Capability of BiFeO 3 -Based Ceramics Via Introduction of Non-Isovalent Ions.

Electrostatic capacitors are emerging as a highly promising technology for large-scale energy storage applications. However, it remains a significant challenge to improve their energy densities. Here, an effective strategy of introducing non-isovalent ions into the BiFeO 3 -based (BFO) ceramic to improve energy storage capability via delaying polarization saturation is demonstrated. Accordingly, an ultra-high energy density of up to 7.4 J cm -3 and high efficiency ≈ 81% at 680 kV m -1 are realized, which is one of the best energy storage performances recorded for BFO-based ceramics. The outstanding comprehensive energy storage performance is attributed to inhibiting the polarization hysteresis resulting from generation ergodic relaxor zone and random field, and generating highly-delayed polarization saturation with continuously-increased polarization magnitudes with the electric field of supercritical evolution. The contributions demonstrate that delaying the polarization saturation is a consideration for designing the next generation of lead-free dielectric materials with ultra-high energy storage performance.