Flexible ultrahigh energy storage density in lead-free heterostructure thin-film capacitors

Flexible Ba2Bi4Ti5O18 and BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 heterostructure thin-film capacitors were deposited onto LaNiO3 buffered fluorophlogopite mica substrates using a cost-effective all-solution chemical solution deposition method. The Ba2Bi4Ti5O18 film showed a high recoverable energy storage density (Ure) of 41.2 J/cm3 and efficiency (η) of 79.1%. The BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 film showed improved energy storage properties with an ultrahigh Ure of 52.6 J/cm3 and η of 75.9% due to its enhanced breakdown field strength and polarization. Meanwhile, both films showed good mechanical flexibility, excellent fatigue endurance up to 5 × 108 cycles, and excellent thermal stability over a wide temperature range from room temperature to 160 °C. These results indicate that the lead-free, flexible Ba2Bi4Ti5O18 and BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 heterostructure thin film capacitors show promise in the field of flexible electronics.