All-Inorganic Flexible Embedded Thin-Film Capacitors for Dielectric Energy Storage with High Performance

As passive components in flexible electronics, the dielectric capacitors for energy storage are facing the challenges of flexibility and capability for integration and miniaturization. In this work, the all-inorganic flexible dielectric film capacitors have been obtained. The flexible capacitors show a desirable recoverable energy density (Wrec) of 40.6 J/cm3 and a good energy efficiency (η) of 68.9%. Moreover, they have no obvious deterioration on both the Wrec and η after 104 times of mechanical bending cycles or under the bending state with a curvature radius of 4 mm. Besides, the outstanding stability of the capacitors against cycle fatigue over fast 106 charge–discharge cycles is demonstrated. Most importantly, they work properly at a wide temperature range from −120 to 150 °C with Wrec > 15 J/cm3 and η > 70%. These fascinating performances endow the flexible capacitors with huge potential application in the future “microenergy storage” system in flexible electronics.