Optimization of energy-storage performance of Mn-doped BaZr_0.2Ti_0.8O₃ lead-free ferroelectric thin films by the sol–gel method

Dielectric capacitors have been widely studied for energy storage applications in pulsed power electronic and electrical systems due to their fast charge/discharge rate and high power density. In this work, the lead-free ferroelectric BaZr_0.2Ti_0.8O₃–0.02 MnO₂ (BZT-0.02 Mn) thin films are prepared by a sol–gel method on Pt(111)/Ti/SiO₂/Si(100) substrates. The crystal structure, surface morphology, ferroelectric properties, leakage behavior, energy storage properties and stability of the films are systematically investigated. The BZT-0.02 Mn thin films exhibit relatively high recoverable energy storage density of 32.3 J/cm³ and energy storage efficiency of 62% at 3700 kV/cm. In addition, the frequency-insensitive stability from 0.1 kHz to 10 kHz, long-term fatigue resistance up to 10⁷ switching cycles and high temperature stability in a range of 20 °C to 120 °C are also achieved. The results show that the BZT-0.02 Mn thin film is a promising lead-free dielectrics for application in energy storage. Graphical Abstract: [Figure not available: see fulltext.]