Enhanced energy density and electric cycling reliability via MnO2 modification in sodium niobate‐based relaxor dielectric capacitors

Abstract

Sodium niobate (NaNbO3)‐based dielectrics have received much attention for energy storage applications due to their low‐cost, lightweight, and nontoxic nature. The field‐induced metastable ferroelectric phase in NaNbO3‐based dielectrics, however, leads to a large hysteresis of the polarization–electric field (P–E) loops and hence deteriorate the energy storage performance. In this study, the hysteresis was successfully reduced by introducing Bi3+ and Ti4+ into A‐site and B‐site of NaNbO3, respectively. MnO2 addition was added to further increase the ceramic density and enhance the cycling reliability. As a result, a high recoverable energy density of 4.3 J/cm3 and a high energy efficiency of 90% were simultaneously achieved in the ceramic capacitor at an applied electric field of 360 kV/cm. Of particular importance is that the ceramic capacitor exhibits a stable energy storage properties over a wide temperature range of −70 to 170 °C, with much improved electric cycling reliability up to 105 cycles.