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

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. Graphic abstract: [Figure not available: see fulltext.]