Domain dynamics engineering in ergodic relaxor ferroelectrics for dielectric energy storage

A trade-off relationship between large polarization and weak hysteresis always exists in ferroelectric capacitors due to the dynamic characteristics of electric domains, which causes challenges in obtaining considerable energy storage density and efficiency. Herein, we propose a strategy of domain dynamics in Bi _{5- x}La _xTi ₃AlO ₁₅ ergodic relaxor ferroelectric films to engineer the evolution of the electric domains during polarization. It is shown that loosely correlated ergodic nanodomains in Bi ₄LaTi ₃AlO ₁₅ film are rapidly arranged and grow into long-range-ordered macroscopic domains during charge, while recovering to the primary disordered states during discharge. Such evolution of domains induces nearly hysteresis-free, temperature-insensitive double ferroelectric hysteresis loops with large polarization. Ultrahigh energy density of ∼140 J cm ⁻³, efficiency of ∼89.2%, and power density of ∼3070 MW cm ⁻³ are simultaneously obtained with superior stability in an ultra-wide temperature region of −100 to 150°C. Such excellent energy storage performances benefit from the mechanism that microscopic domain dynamics engineer a macroscopic reversible interconversion between relaxor and ferroelectric phases during polarization. This alternative strategy breaks through the limitation in designing high-performance energy storage capacitors.