Synergistic Optimization in a 0.90BaTiO3–0.08Bi(Ni0.5Zr0.5)O3–0.02BiFeO3 Thin Film with High Breakdown Strength and Energy Density

Amorphous thin films have attracted wide attention owing to their high breakdown strength in the field of dielectric ceramic thin-film energy storage. However, improving the polarization strength has been a great challenge for amorphous films due to the inverse relationship between polarization and breakdown strength. Herein, a concept of ternary synergistic optimization design is proposed and proved to be an effective strategy to improve this challenge. BaTiO3–Bi(Ni0.5Zr0.5)O3–BiFeO3 amorphous films are prepared by a sol–gel method. BaTiO3 is chosen as the main component, taking advantage of its large spontaneous polarization. The introduction of Bi(Ni0.5Zr0.5)O3 facilitates the formation of nanoscale crystalline regions. For BiFeO3, Fe2+ and Fe3+ incorporation into thin films bound oxygen vacancy defects and enhanced the polarization, which further improved the energy storage performance. As a result, 0.90BaTiO3–0.08Bi(Ni0.5Zr0.5)O3–0.02BiFeO3 thin film achieves an energy storage density of 114.3 J cm–3 and energy storage efficiency of 87.0%, together with excellent thermal stability in a temperature range of 20–150 °C. This work provides a universal method to improve the polarization and energy storage properties of amorphous films.