Tailoring energy storage performance of BaTiO3–CeO2 lead-free films via nanostructure design and crystalline orientation

Relaxor ferroelectrics are promising for high-performance energy storage applications, particularly in miniaturized electronic devices and power systems. Herein, we investigate the influence of CeO2 doping on the structural and polarization behavior of (1 − x)BaTiO3−xCeO2 [(1 − x)BT−xC, 0.0 ≤ x ≤ 0.5] films. Our results show that the incorporation of CeO2 into BaTiO3 matrix induces chemical and structural heterogeneity, which effectively suppresses hysteresis, achieving a large energy storage density Ue of ∼37.6 J/cm3 and a high efficiency η of ∼80% for 0.7BT-0.3C films grown on Nb-SrTiO3 (001) substrates. The orientation control further refined the energy storage properties, with 0.7BT-0.3C films grown on (110)- and (111)-oriented Nb-SrTiO3 substrates exhibiting improved Ue of 44.8 and 46.8 J/cm3. The frequency and thermal stability analyses revealed that the nanostructured BaTiO3-based films maintained stable energy storage performance across a wide frequency range from 20 Hz to 10 kHz, and temperature range from 25 to 160 °C. These findings suggest the potential of nanostructure engineering and orientation control in improving the energy storage performance of BaTiO3-based films for advanced applications.