High energy storage performances in lead-free BaBi3.9Pr0.1Ti4O15 relaxor ferroelectric films

Lead-free BaBi4-xPrxTi4O15 (BBPT) relaxor ferroelectric films were prepared by the sol−gel method. A giant recoverable energy storage density of 47.8 J/cm3 and a high efficiency of 66.45% are obtained in BaBi3.9Pr0.1Ti4O15 (BBPT10) films. Specifically, the energy utilization ratio reaches as high as 0.0373. After 1 × 109 cycles, both the energy storage density and the efficiency can still be perfectly maintained. Moreover, BBPT10 capacitors possess outstanding thermal stability of energy storage performance over a wide temperature range of −20 °C to 120 °C. The breakdown strength reaches 1285 kV/cm. Such superb energy storage performances are mainly attributable to strong relaxation behaviors of the layered perovskite structure derived from the lattice distortion and structural transformation. BBPT based films provide a exploring area of lead-free ferroelectric materials widely applicable in energy storage devices.