Optimization of Energy Storage Properties in Lead-Free Barium Titanate-Based Ceramics via B-Site Defect Dipole Engineering

The development of lead-free dielectric materials with environmental friendliness has been of great significance to enhance the capability of electronic devices owing to their excellent energy storage properties (ESPs). Learning from the doping mechanism of ABO3, moderate defects such as oxygen vacancies (VO″) produced by chemical modification are beneficial to increase the ESP of the dielectric materials. Hence, we propose an innovative design strategy to stimulate the potential capability of energy storage in BaTiO3 (BT)-based ceramics by B-site [LiTi–Vo]− defect dipole engineering. A systematic analysis proves that the Li-occupied Ti-site in the unit cell of BT moves along the [001] direction. In this case, Li+ forms the defect dipoles with neighboring VO″, producing defect polarization as the interelectric field. It resists the applied electric field, resulting in smaller remnant polarization (Pr) and dielectric breakdown strength (BDS) to optimize the ESP. As expected, the Li+-doped BT ceramic through defect dipole engineering exhibits a low Pr of 2.29 μC/cm2 and a giant gap in the polarization (ΔP) up to 35.73 μC/cm2, which is superior to the pure BT ceramic (Pr of 19.98 μC/cm2 and ΔP of 18.86 μC/cm2) and other element (such as Zr4+ and Sr2+)-doped BT materials. More importantly, it satisfies the requirement of a larger BDS of 140 kV/cm with the corresponding recoverable energy storage density of 1.11 J/cm3. Our research focuses on the B-site defect dipole engineering, which is expected to benefit energy storage material design.