Near-Zero Energy Loss in Sr 1–1.5 x Bi x TiO 3 Dielectric Ceramics for High-Efficiency Energy Storage

High-efficiency Sr 1–1.5 x Bi x TiO 3 dielectrics with near-zero energy loss were synthesized via the citrate method. Results showed that Bi 3+ doping induces local lattice distortion and facilitates the formation of polar nanoregions embedded within the cubic matrix, thereby enhancing the polarization intensity. The optimal composition ( x = 0.01) achieves a large recoverable energy density ( W rec ) of 3.51 J/cm 3 and an ultrahigh efficiency (η) of 97.58% at an electric field of 484 kV/cm, with a high figure of merit ( W F = 145) competitive among lead-free dielectric ceramics. First-principles calculations reveal that the enhanced energy storage performance with promoted polarization stems from two synergistic effects: the disruption of the centrosymmetric structure by Bi 3+ -induced lattice distortion, and the contribution of local polarization from strong hybridization between Bi-6s and O-2p orbitals. These findings offer a promising strategy for designing high-performance lead-free dielectric materials for energy storage applications.