Improved energy storage performance in flexible (PbLa)ZrO₃ thin films via nanocrystalline engineering

Flexible film capacitors with high energy storage density (W_rec) and charge-discharge efficiency (η) are a cutting-edge research topic in the current field of energy storage. In this work, flexible all-inorganic (Pb_0.91La_0.06)ZrO₃ ((PbLa)ZrO₃) thin films are designed and integrated on mica substrates by a sol-gel method. By adjusting the rapid annealing temperature of (PbLa)ZrO₃ thin films, the influence of the microstructure on the electrical properties and energy storage performances has been comprehensively investigated. The results show that the (PbLa)ZrO₃ thin films annealed at 550 °C have a nanocrystalline structure, which is beneficial to reducing energy loss and improving insulation performance. A large W_rec of 42.0 J cm⁻³ and an outstanding η of 90.2% are achieved in (PbLa)ZrO₃ films via nanocrystalline engineering. Moreover, the flexible capacitor films exhibit good temperature stability (25-140 °C), frequency stability (1-10 k Hz), bending stability (10⁴ cycles) and electric fatigue stability (10⁷ cycles). This work is expected to promote the application of (PbLa)ZrO₃-based film capacitors in energy storage systems.