Enhanced electrocaloric response and energy storage performance of Li-substituted BaTiO3 ceramics

Recently, ferroelectric and antiferroelectric ceramic materials have gained a lot of interest for the development of environment-friendly highly-efficient electrocaloric refrigeration and energy-storage devices. In this work, lead-free Ba_1−xLi_xTiO₃ ceramics with x = 0, 0.01, 0.02, 0.03, 0.04, and 0.05 were synthesized by the conventional solid-state reaction method, and the effect of Li doping on dielectric, leakage current, ferroelectric, electrocaloric, and energy storage properties of BaTiO₃ ceramics was systematically investigated. The XRD and Raman studies confirmed that the structure of Ba_1−xLi_xTiO₃ remains tetragonal as for BaTiO₃. The Li substitution shifted the phase transition (T_C) of BaTiO₃ slightly towards the lower temperature side. Significant drop in leakage current was observed with an addition of Li content. The maximum values of the electrocaloric effect (ΔT), electrocaloric responsivity, and coefficient of performance were found to be 1.44 K, 0.24 × 10⁻⁶ K m/V, and 5.75, respectively, for x = 0.04 at an applied field of 60 kV/cm near the Curie temperature. The maximal value of energy storage density was found to be 0.42 J/cm³ with an energy storage efficiency of 60% for x = 0.05. Our results suggested that lead-free Ba_1−xLi_xTiO₃ ceramic material is a promising candidate for potential applications in solid-state refrigeration technology and high-efficiency energy storage devices.