Simultaneously realizing high energy density and high efficiency in NaNbO3–BaTiO3‐based ceramic capacitors

Abstract Dielectric capacitors, which can achieve tremendous power density and ultrafast charge/discharge speed, are crucial components for high power equipment. Yet, the synchronous achievement in high recoverable energy density ( W rec ) and high efficiency ( η ) is a long‐term difficulty for dielectric ceramics. Herein, the (0.85 − x )NaNbO 3 –0.15BaTiO 3 – x Bi(Mg 1/3 Ta 2/3 )O 3 (NN–BT– x BMT) relaxor ferroelectric ceramics were proposed and studied. The doping of BMT was conducive to promoting the microstructure and bandgap and improving the dielectric relaxation properties of NN–BT ceramics. Finally, the sample of x = 0.10 presented a high W rec of 5.9 J/cm 3 and a high η of 90% simultaneously. In addition, the sample also exhibited superb charge/discharge performances with large power density ( P D = 137 MW/cm 3 ) and fast charge/discharge speed ( t 0.9 = 39 ns). The above results reveal that the NaNbO 3 ‐based ceramics could serve as potential alternatives for advanced dielectric capacitors.