Boosting energy storage performance with lead-free relaxor ferroelectric in BNT-based ceramics via introducing scheelite La2WTiO8†
Abstract
Driven by the information industry, there is an urgent need for lead-free ceramic materials exhibiting excellent recoverable energy storage density (Wrec) and energy storage efficiency (η) to meet the practical application requirements of pulse power capacitors. Among these, Bi0.5Na0.5TiO3 (BNT) stands out as a highly promising and competitive environmentally-friendly ceramic material due to its exceptional dielectric properties. However, premature polarization saturation and low dielectric breakdown field (Eb) have been major obstacles to its practical application. Herein, the scheelite-structured La2WTiO8 (LWT) is successfully integrated with the perovskite-structured BNT to enhance the energy storage performance (ESPs) of BNT-based ceramics. The obtained results show that LWT doped into BNT matrix destroys the long-term ferroelectric order and effectively promotes the formation of polar nanoregions, which enhance Eb and delay polarization saturation. Ultimately, the optimized composition achieves the expected Wrec (∼6.3 J cm−3) and η (∼78.9%) at 400 kV cm−3 with excellent temperature stability (<9% variation in the temperature range of 20–200 °C) and frequency stability (∼2.8% variation in the frequency range of 1–100 Hz). In addition, a fast discharge performance of t0.9 ∼ 62.6 ns and a high power density of 105.71 MW cm−3 at 200 kV cm−1 are achieved. This work proposes a strategy to obtain high comprehensive ESPs of BNT-based ceramics, offering new prospects for the development of advanced pulse capacitors.