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 ABO 3 , moderate defects such as oxygen vacancies ( ″ V O ) 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 BaTiO 3 (BT)-based ceramics by B-site [Li Ti − V o ] − 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 ″V O , producing defect polarization as the interelectric field. It resists the applied electric field, resulting in smaller remnant polarization (P r ) and dielectric breakdown strength (BDS) to optimize the ESP. As expected, the Li + -doped BT ceramic through defect dipole engineering exhibits a low P r of 2.29 μC/cm 2 and a giant gap in the polarization (ΔP) up to 35.73 μC/cm 2 , which is superior to the pure BT ceramic (P r of 19.98 μC/cm 2 and ΔP of 18.86 μC/cm 2 ) and other element (such as Zr 4+ and Sr 2+ )-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/cm 3 . Our research focuses on the Bsite defect dipole engineering, which is expected to benefit energy storage material design.

Dielectric capacitors with excellent energy storage performance (ESP) are in great demand in the power electronics industry due to their high power density. For the dielectric materials, the dielectric breakdown strength (BDS) is the key factor to improve ESP, which is the focus and bottleneck of current research, especially in the relaxor ferroelectric (RFE) materials with already low residual polarization (Pr). Here, we stimulate the ESP of the BaTiO3 (BT)‐based RFE ceramics by band structure engineering. The Ta element is selected to enhance the band gap of doped ceramics, occupying Ti‐site in supercell of BT and optimizing the bonds length of Ti‐O bond to increase the energy band of Ti 3d states. In this way, the band gap of the doped ceramics is efficiently enhanced from 1.8 eV to 2.22 eV resulting in the large BDS. Prospectively, combined with the advantage of fine grain size, the highest recoverable energy storage density (Wrec) of 2.85 J/cm3 is obtained at 350 kV/cm and the ultra‐high energy efficiency (η) of 95.26% is found at 200 kV/cm. Our work reveals the relationship between elements doping in B‐site and band structure, being expected to benefit for designing energy storage materials.

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