Design of an all-inorganic flexible Na0.5Bi0.5TiO3-based film capacitor with giant and stable energy storage performance†
With the significant advancement of portable/wearable electronics, the demand for flexible electronic devices has significantly increased; in the field of energy storage, the development of dielectric capacitors is still facing challenges due to the difficulty in integrating large recoverable energy storage density (Wrec), high efficiency (η), and robust bendability with fully flexible pulsed power systems operating in harsh environments. Herein, the all-inorganic flexible Mn-doped (1−x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xSrTiO3 (Mn:NBT-BT-xST, x = 0.30, 0.45, 0.60, and 0.75) film capacitors were obtained via simple one-step fabrication on a mica substrate. The Mn:NBT-BT-0.45ST film capacitor shows the desirable Wrec of 76.1 J cm−3 and the high η of 80.0% owing to the predominant relaxor feature and weak antiferroelectric-like behavior. Furthermore, stable properties in the frequency range from 500 Hz to 20 kHz and the ultra-wide working temperature range of −100 to 200 °C and robust fatigue and retention endurance over 108 cycles and 103 s were achieved, respectively. Moreover, mechanical bending processes at the small radius of 2 mm or even 104 mechanical bending cycles had no influence on the energy storage performances. This study is expected to pave the way for the application of high-performance bendable dielectric film capacitors in energy storage and flexible electronic devices.