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

Here, large-scaled flexible Ba(Zr0.35Ti0.65)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(Zr0.35Ti0.65)O3 film capacitors show excellent thermal stability with recoverable energy density (Wrec) of over 65.1 J/cm3 and efficiency (η) of over 72.9%, which presents the highest Wrec 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(Zr0.35Ti0.65)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.