Enhanced Energy Storage Properties of Highly Polarized BMT-Based Thin Films through the Multiscale Structure Synergistic Regulation Strategy.

For solving the trade-off relationship of the polarization and breakdown electric field, ferroelectric films with high polarization are playing a critical role in energy storage capacitor applications, especially at moderate/low electric fields. In this work, we propose a multiscale structure (including defect, domain, and grain structures) synergetic optimization strategy to optimize the polarization behavior and energy storage performances of BiMg _0.5 Ti _0.5 O ₃ (BMT) ferroelectric films by introducing Sr _0.7 La _0.2 TiO ₃ (SLT) without compromising the breakdown strength. At a moderate electric field of 2917 kV/cm, a high discharge density of 72.2 J/cm ³ has been achieved in 0.9BMT-0.1SLT films, together with good frequency, thermal, and cycle stabilities for energy storage. Importantly, the phase difference Δφ is utilized to quantitatively evaluate the polarization switching mobility of the ferroelectric domain/PNRs at an external electric field stimulation. This research demonstrates that a multiscale structure optimization strategy could effectively regulate the energy storage performance, and ecofriendly BMT-based materials are promising candidates for next-generation energy storage capacitors, especially at moderate/low electric fields.