Ultrahigh energy storage performances derived from the relaxation behaviors and inhibition of the grain growth in La doped Bi5Ti3FeO15 films

Abstract Developing environment-friendly film capacitors, which possessing a high energy storage performance, an extra wide working temperature range and a longest lifetime are desirable in applications owning to energy shortage and environmental pollution. Here, lead-free Bi5-xLaxTi3FeO15 films with four-layer Aurivillius structure were fabricated by the sol–gel method. It is revealed that the introduction of lanthanum ions into Bi5Ti3FeO15 films induces relaxation behaviors and inhibits grain growth, thus improving the energy storage performances. Bi4LaTi3FeO15 films achieved a large recoverable energy storage density of 83.2 J/cm3 and a high efficiency of 79.1% under 3460 kV/cm. Moreover, Bi4LaTi3FeO15 films exhibited excellent energy storage performances in fatigue endurance and thermal stability. This work demonstrates that the route through rare-earth doped multilayered perovskite ferroelectric films is an effective approach to enhance energy storage properties.