Simultaneously enhanced energy density and discharge efficiency of (NaBi)SrTiO-La(TaNb)O lead-free energy storage ceramics grain inhibition and dielectric peak flattening engineering.

Energy storage ceramics are widely favored for their rapid charging/discharging speed, good temperature stability and large power density. Nevertheless, most lead-free energy storage ceramics can achieve excellent energy storage density () only under extremely high breakdown electric field and usually possess inferior efficiency (). In this research, neoteric (1 - )(NaBi)SrTiO-La(TaNb)O (NBST-LTN) ceramics were designed by grain inhibition and dielectric peak flattening engineering to enhance and simultaneously under a low electric field (≤150 kV cm). In particular, in one aspect, multiple co-doping of the elements La, Ta and Nb as excellent grain growth inhibitors reduces the concentration of oxygen vacancies and refines the grain size to increase the breakdown strength. In another aspect, partial ion substitution in the A/B sites of BNST ceramics breaks the ferroelectric long-range order to generate polar nanoregions, resulting in a remarkable decrease in remanent polarization. Moreover, the incorporation of LTN distorts the lattice, causing a shift towards room temperature and flattening of dielectric peaks to promote the temperature/frequency stabilities significantly. Ultimately, the ultrahigh of 92.49%, promising of 2.09 J cm and large of 1.94 J cm under 148 kV cm are achieved concurrently accompanied by the optimistic temperature, frequency and cyclic stabilities in the BNST-0.025LTN ceramic. Besides, outstanding power and current densities ( and ) of 67.86 MW cm and 848.29 A cm are procured in the BNST-0.025LTZ ceramic under a low electric field of 160 kV cm. The present strategies of grain inhibition and dielectric peak flattening engineering provide an effective approach to exploit novel lead-free ceramics with excellent energy storage properties.