High-performance energy-storage ferroelectric multilayer ceramic capacitors via nano-micro engineering

The theory of obtaining high energy-storage density and efficiency for ceramic capacitors is well known, e.g. increasing the breakdown electric field and decreasing remanent polarization of dielectric materials. How to achieve excellent energy storage performance through structure design is still a challenge. Here, we propose a synergetic nano-micro engineering approach to achieve high energy-storage behavior in (1 − x)(0.65Bi_0.5Na_0.5TiO₃-0.35SrTiO₃)-xLa(Mg_1/2Zr_1/2)O₃ multilayer ceramic capacitors (MLCCs). The introduction of La(Mg_1/2Zr_1/2)O₃ not only promotes the domains to transform into polar nano-regions, but also improves microscale-structure homogenization, leading to enhanced relaxation characteristic and dielectric breakdown strength. Moreover, constructing a multilayer structure by decreasing the thickness of the dielectric layer to ∼10 μm further increases the dielectric breakdown strength to 1050 kV cm⁻¹. This nano-micro engineering results in a high energy density of 13.5 J cm⁻³ together with a large efficiency of 90% in the MLCC with x = 0.15. The MLCC also exhibits excellent temperature and frequency stability, where the variations in energy density are just 1% (20-120 °C) and 2% (1-100 Hz), respectively. This material design strategy based on nano-micro engineering demonstrates a positive size effect on energy-storage performances, promoting the development of the ferroelectric family in energy-storage fields.