Double enhancement of energy storage density in relaxor ferroelectric 0.8BaTiO₃-0.2BiScO₃ by Li defect-regulated strategy

To meet the ever-increasing demands for pulsed power technologies, the development of lead-free dielectric ceramics with a large energy storage density (W_rec) and high energy storage efficiency (η) is crucial for enhancing the electrical performance of power capacitive devices. The conventional solid-solution, while effective in suppressing long-range order and improving energy storage performances, often results in a reduction of maximum polarization. This reduction necessitates the application of a larger electric field to obtain a relatively high W_rec. Herein, an effective strategy to enhance W_rec again via inducing Li-related defect dipoles is proposed. By introducing (Bi_0.5Li_0.5)TiO₃ into 0.8BaTiO₃-0.2BiScO₃ matrix, the polarization contribution from defect dipoles together with intrinsic polarization induces an at least two-time enhancement in P_max. Our findings indicate ∼62.9 % enhancement in the W_rec of 0.8BT-0.2BS, elevating from 2.56 J cm⁻³ to 4.17 J cm⁻³ at electrical field of 300 kV cm⁻¹, while preserving an energy storage efficiency of 90.35 %. Furthermore, it also exhibits good thermal stability with the variations of ΔW_rec < 3 % and η< 5 %. This research introduces a novel strategy for defect regulation strategy in the design of high-performance dielectric materials, which is expected to expedite the optimization of the advanced energy storage capacitors. © 2024 Elsevier B.V.