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Apart from discharge energy density (Wr) and discharging time (t0.9), thermal stability and anti-fatigue for charge-discharge performance are also the important performance indexes for dielectric pulsed capacitor. Na0.5Bi0.5TiO3 based ceramics are usually accompanied by huge electric field-induced strain when appling electric field, resulting in the fatigue phenomenon and thermal accumulation effect in the cycling process. In this work, Na0.5Bi0.5TiO3-xNaNbO3 (NBT-xNN) ferroelectric relaxor ceramic has been prepared by the solid state reaction process. The effect of NaNbO3 content on microstructures, impedance spectroscopy, electric-field-induced strain and charge-discharge performance of NBT-xNN ceramics have been investigated systematically. Results indicate the proper percent of NaNbO3 could favor the formation of polar nanoregions (PNRs), which leads to the diffusion of phase transition and the diminution of electromechanical strain. Therefore, the high thermal stability and anti-fatigue for charge-discharge property has been achieved in NBT-xNN ceramics. An enhanced discharging energy density of 2.44 J cm−3 along with discharge time of 0.31 μs could be obtained in the NBT-xNN with x = 0.3, and a very stable discharge energy density of 2.06 J cm−3 concomitantly with discharge time less than 0.37 μs could be gained in a wide temperature range of 20–150 °C with a fluctuation of ±4% after 104 charge/discharge cycles. This work would contribute to the development of charge-discharge system, especially dielectric capacitor, for green pulsed power devices.

Pyroelectric energy harvesting is considered a highly promising technology for converting low-grade waste heat into electricity, but the practical applications of pyroelectric generators is limited by the their poor energy densities and instability. In this work, we construct SiO2 networks with low heat capacities in NBT-BZT ceramics. These networks improve the heat transfer (dT/dt) and broaden the pyroelectric temperature region of the composites by reducing heat absorption capacity, thereby leading to high pyroelectric energy density and stability. The temperature range of the NBT-BZT composite with 0.1 wt% SiO2 for pyroelectric coefficient higher than 20 × 10−4 C m−2 K−1 is increased to 20 °C, This increase results in the high thermostability of energy harvesting. In addition, the NBT-BZT: 0.1 wt% SiO2 composites show an optimized pyroelectric energy density of 110 u J cm-3, nearly three times that of the pure NBT-BZT ceramics. This work is beneficial for the application of high-performance pyroelectric materials for devices used in energy harvesting.