Fatigue‐Free and Bending‐Endurable Flexible Mn‐Doped Na0.5Bi0.5TiO₃‐BaTiO₃‐BiFeO₃ Film Capacitor with an Ultrahigh Energy Storage Performance

As the rapid development of intelligent systems moves toward flexible electronics, capacitors with extraordinary flexibility and an outstanding energy storage performance will open up broad prospects for powering portable/wearable electronics and pulsed power applications. This work presents a simple one‐step process to fabricate a flexible Mn‐doped 0.97(0.93Na 0.5 Bi 0.5 TiO 3 ‐0.07BaTiO 3 )‐0.03BiFeO 3 (Mn:NBT‐BT‐BFO) inorganic thin film capacitor with the assistance of a 2D fluorophlogopite mica substrate. The film element, which has a high breakdown strength, great relaxor dispersion, and the coexistence of ferroelectric and antiferroelectric phases, has a high recoverable energy storage density ( W rec ≈81.9 J cm −3 ), high efficiency (η ≈64.4%), superior frequency stability (500 Hz–20 kHz), excellent antifatigue property (1 × 10 9 cycles), and a broad operating temperature window (25–200 °C). The all‐inorganic Mn:NBT‐BT‐BFO/Pt/mica capacitor has a prominent mechanical‐bending resistance without obvious deterioration in its corresponding energy storage capability when it is subjected to a bending radius of 2 mm or repeated bending for 10 3 cycles. This work is the first demonstration of an all‐inorganic flexible film capacitor and sheds light on dielectric energy storage devices for portable/wearable applications.