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

Sodium niobate (NaNbO 3 )‐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 NaNbO 3 ‐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 Bi 3+ and Ti 4+ into A‐site and B‐site of NaNbO 3 , respectively. MnO 2 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/cm 3 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 10 5 cycles. Graphic abstract