Simultaneously achieving high energy-storage efficiency and density in Bi-modified SrTiO3-based relaxor ferroelectrics by ion selective engineering

Dielectric capacitors possess high power density and ultrafast charge/discharge speed in comparison to other electrical energy storage devices, but lag behind in energy density, efficiency and thermal stability, which has been a major hurdle for industrial applications. Here we demonstrate that high energy efficiency of 97%, together with a large energy density of 3.71 J/cm3 realized at 340 kV/cm as well as satisfactory thermal stability of energy density (with minimal variation of 10%), and energy efficiency ( 97%) within a broad temperature range at 270 kV/cm, can be achieved in Bi-modified SrTiO3 solid-solution ceramics though ion selective engineering. The formation of polar nano-regions with high dynamic, rapid reversibility, and low switching energy barriers, as confirmed by in situ piezoresponse force microscope and Raman, enables linear-like polarization-field response and highly thermal stable polarization response with concurrently enhanced energy efficiency and density. Additionally, the designed ceramic also exhibits large power density of 114.3 MW/cm3, medium discharge energy density of 1.64 J/cm3, and ultrafast discharge rate of 57 ns along with excellent thermal and fatigue endurances. These findings suggest that ion selective engineering-designed Bi-modified SrTiO3 relaxor ferroelectric ceramic can offer realistic solutions to successfully tailor pulsed power capacitors for electrostatic energy storage.