Fatigue-Free Aurivillius Phase Ferroelectric Thin Films with Ultrahigh Energy Storage Performance

Dielectric capacitors have become a key enabling technology for electronics and electrical systems. Although great strides have been made in the development of ferroelectric ceramic and thin films for capacitors, much less attention has been given to preventing polarization fatigue, while improving the energy density, of ferroelectrics. Here superior capacitive properties and outstanding stability are reported over 10⁷ charge/discharge cycles and a wide temperature range of −60 to 200 °C of ferroelectric Aurivillius phase Bi_3.25La_0.75Ti₃O₁₂-BiFeO₃ (BLT-BFO), which represents one of the best capacitive performances recorded for the ferroelectric materials. The modification of BLT thin films with BFO overcomes the constraints of ferroelectric Aurivillius compounds and presents an unprecedented combination of the ideal features including improved polarization, reduced ferroelectric hysteresis, and lowered leakage current for high-energy-density capacitors. Given the lead-free and fatigue-free nature of this Aurivillius phase ferroelectric, this work unveils a new approach towards high-performance eco-friendly ferroelectric materials for electrical energy storage applications.