Local Heterogeneous Polarization Enhanced Superior Low-Field Energy Storage Performance in Lead-Free Relaxor Ferroelectric Ceramics
Ziming Cai, Hang Yang, Chaoqiong Zhu, Shiheng Li, Bing Luo, Aoyu Li, Xinheng Li, Zhaobo Tian, Peizhong Feng
Abstract
High-performance ceramic dielectrics play a crucial role in the development of next-generation advanced high/pulsed power capacitors. Thereby, the utilization of relaxor ferroelectric ceramics in energy storage applications is of great interest due to the small hysteresis, while the undesirable discharge energy density caused by the limited polarization, especially under a low applied electric field is still a huge challenge in practical applications. To reconcile the relationship between polarization and breakdown strength, a local heterogeneous polarization strategy is delivered by introducing multicomponents into Bi 0.5 Na 0.5 TiO 3 -based ceramics, which can weaken the nonlinearity of the P – E relation and delay the saturation polarization simultaneously. A large polarization of 38.1 μC/cm 2 is reached at a relatively low electric field of 280 kV/cm in the BB-35BN ceramic. Meanwhile, a large energy storage density of 4.11 J/cm 3 together with an ultrahigh energy efficiency of 95.6% is achieved. The microscale component fluctuations are observed by electron probe X-ray microanalysis (EPMA). The significant lattice distortions can be detected via high-resolution transmission electron microscopy (HR-TEM), which contributes to the overall polarization strength. Additionally, this ceramic system has excellent temperature stability (Δ W dis ≤ 15%, from 25 to 190 °C) and fatigue stability (Δ W dis ≤ 2.48%, after 10 6 cycles), thereby showing great potential in practical high-temperature energy storage applications.