Flexible lead-free oxide film capacitors with ultrahigh energy storage performances in extremely wide operating temperature

Here, large-scaled flexible Ba(Zr_0.35Ti_0.65)O₃ ferroelectric film capacitors not only exhibit ultrahigh energy storage performances but also have excellent mechanical flexibility and ferroelectric fatigue endurance. In ultra-wide temperature range from −100 °C to 200 °C, the flexible Ba(Zr_0.35Ti_0.65)O₃ film capacitors show excellent thermal stability with recoverable energy density (W_rec) of over 65.1 J/cm³ and efficiency (η) of over 72.9%, which presents the highest W_rec obtained up to now not only in flexible polymer film dielectric capacitors but also in the ceramic film capacitors including lead-free and lead-based film capacitors on rigid substrates in this measuring temperature range. All these results demonstrate that the flexible Ba(Zr_0.35Ti_0.65)O₃ film capacitors have huge potential in the applications of flexible electronics operated in cold polar regions, extreme altitudes and outer space, as well as high temperature regions.