Internal-strain release and remarkably enhanced energy storage performance in PLZT–SrTiO3 multilayered films

The multilayered composite films combining antiferroelectric (AFE) Pb0.97La0.02(Zr0.95Ti0.05)O3 (PLZT) with paraelectric (PE) SrTiO3 (STO) have been fabricated by the sol–gel method, and their ferroelectric and energy storage performances were carefully investigated. It was revealed that both the dielectric breakdown strength (Eb) and the maximum polarization (Pm) in the multilayered composite films are increased. Consequently, an ultra-high and recoverable energy storage density (Wre) of ∼101 J/cm3 and a high efficiency (η) of ∼62% were achieved in the composite film with an 18 wt. % STO content. The enhanced Wre in the multilayered composite is attributed to the internal-strain release of the PLZT layers and charge blocking by the STO layers with significantly enhanced Eb. The results suggest an effective way of improving the energy storage performances by combining AFE PLZT and PE STO.