High pyroelectric response over a broad temperature range in NBT-BZT: SiO2 composites for energy harvesting

Abstract

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.