Enhanced Energy Storage Performance in BaTiO3/(Pb, La, Ca)TiO3/BaTiO3 Sandwich Thin Films Enabled by Rapid Annealing Engineering

Dielectric thin film capacitors are characterized by high energy density, rapid charge-discharge, high usable efficiency, and high breakdown field strength, and are widely used in electronics and novel energy technologies. To address the trade-off among polarization, efficiency, and breakdown strength in traditional single-layer dielectric capacitors, this study employs a low-cost sol-gel method to synthesize a BTO/PLCT/BTO sandwich structure film. By optimizing the annealing process, an amorphous/ferroelectric/amorphous multilayer phase structure coexistence was achieved. With increasing annealing temperature, the polarized nanoregions within the amorphous BTO layer expand, while the PLCT layer crystallizes into a ferroelectric phase. At 600 ° C, the synergistic amorphous/ferroelectric/amorphous phase effect is optimized, yielding an energy storage density of 80 J/cm 3 and an efficiency of 86% under an electric field of 5.4 MV/cm. Meanwhile, from room temperature to 150 ° C, the film achieves excellent dielectric and energy storage stability over a wide temperature range (variation rates of dielectric property and energy storage performance below 5%). After 10 9 fatigue cycles, the film still maintains the stability of its electrical performance (variation rate of Δ W rec /Δ W rec-initial ≤ 4%). This amorphous/ferroelectric/amorphous composite film overcomes the trade-off among polarization, usable efficiency, and breakdown strength inherent in single-phase materials, providing a viable strategy for fabricating high-stability energy storage films.