Flexible Lead-Free BaSrTiO/0.4BiFeO-0.6SrTiO Dielectric Film Capacitor with High Energy Storage Performance.

Ferroelectric thin film capacitors have triggered great interest in pulsed power systems because of their high-power density and ultrafast charge-discharge speed, but less attention has been paid to the realization of flexible capacitors for wearable electronics and power systems. In this work, a flexible BaSrTiO/0.4BiFeO-0.6SrTiO thin film capacitor is synthesized on mica substrate. It possesses an energy storage density of ~ 62 J cm, combined with an efficiency of ~ 74% due to the moderate breakdown strength (3000 kV cm) and the strong relaxor behavior. The energy storage performances for the film capacitor are also very stable over a broad temperature range (-50-200 °C) and frequency range (500 Hz-20 kHz). Moreover, the and are stabilized after 10 fatigue cycles. Additionally, the superior energy storage capability can be well maintained under a small bending radius ( = 2 mm), or after 10 mechanical bending cycles. These results reveal that the BaSrTiO/0.4BiFeO-0.6SrTiO film capacitors in this work have great potential for use in flexible microenergy storage systems.