Giant comprehensive capacitive energy storage in lead-free quasi-linear relaxor ferroelectrics via local heterogeneous polarization configuration

Abstract

Dielectric ceramic capacitors have shown extraordinary promise for physical energy storage in electrical and electronic devices, but the major challenge of simultaneously achieving high recoverable energy density (W_rec), ultrahigh efficiency (η), and exceptional stability still exists and has become a long-standing obstacle hindering the practical applications of next-generation pulsed power capacitors. Herein, we report the design of new lead-free quasi-linear relaxor ferroelectrics via the construction of local heterogeneous polarization configurations including ultra-small and highly dynamic polar nanoregions with low energy barriers, local structure heterogeneity, and highly stable local structures, generating substantially delayed polarization saturation and minimized polarization switching hysteresis at a large breakdown electric field. The designed new relaxor can deliver a large W_rec (≈7.01 J cm⁻³), concurrent with an ultrahigh η (≈94.3%) and Vickers hardness H_v (≈8.22 GPa), as well as superior temperature/frequency/cycling stabilities and excellent charging–discharging properties (power density P_D ≈ 110.6 MW cm⁻³ and discharge speed t_0.9 ≈ 30 ns), showing giant comprehensive capacitive energy storage. The achievement of such high-efficiency capacitive energy storage bridges the gap between lead-free and lead-based dielectric ceramics and can facilitate the development of cutting-edge capacitors.