Customizing the trade-off between breakdown strength and polarizability in BaTiO3-based ceramics for superior energy storage capability

Electrostatic capacitors as vital electronic components are extensively studied for applications in lightweight electrification systems. However, it is imperative to develop electrostatic capacitors with concurrently high breakdown strength and polarizability to achieve large energy densities. Herein, we design a weakly coupled relaxor ferroelectric ceramic of BaTiO3-K0.5Bi0.5TiO3-Bi(Ni2/3Nb1/3)O3 (BT-BKT-BNN). The introduction of BKT matrix with A-site lone pair effect, greatly increases saturated polarization strength. Additionally, incorporation of BNN with valence mismatched ions Ni2+ and Nb5+ hinders long-range polar coupling and resulted in the creation of polar nanoregions. By combining a high breakdown strength (Eb ~ 700 kV cm-1), large polarization (~ 30.7 µC cm−2), and negligible remnant polarization (< 2 µC cm−2), a remarkable energy density (Wrec) of 6.1 J cm−3 and an efficiency (η) of 87.7% are attained. Specifically, the system demonstrates a superb cycling stability, frequency-insensitive and good temperature stability. This article affords an effective strategy for tailoring high-performance relaxor ferroelectrics.