High Energy Storage Efficiency with Fatigue Resistance and Thermal Stability in Lead‐Free Na0.5K0.5NbO3/BiMnO3 Solid‐Solution Films

The ferroelectric, leakage, dielectric, and energy storage properties of lead‐free Na 0.5 K 0.5 NbO 3 /BiMnO 3 (KNN/BMO) solid‐solution films are investigated. The strong ferroelectric relaxation behaviors of slim ferroelectricity with small remanent polarization and coercive field induce a high energy‐storage density and efficiency at room temperature. The energy density reaches 14.8 J cm −3 , even the efficiency is up to 79.79% under the applied electric field of 985.66 kV cm −1 . Moreover, the energy storage performances of KNN/BMO solid‐solution films exhibit good thermal stability over a wide temperature range and high ferroelectric fatigue endurance after switching 10 6 bipole electrical cycles. KNN/BMO solid‐solution films can replace lead‐based films and other outstanding lead‐free systems in the energy storage performance.