Enhanced electric breakdown strength and excellent storing density in BaTiO3-based ceramic in viscous polymer processing

Abstract

Despite being the key component in modern electronic devices or power systems, ceramic dielectric capacitors have drawbacks like low energy storage density and efficiency that limit their extensively wide application. This work adopted a different route to improve energy storage performance compared with the frequently utilized composition modification. 0.98Ba_0.65Sr_0.245Bi_0.07TiO₃-0.02Ce Pb-free ceramics with different polyvinyl alcohol (PVA) contents were prepared through viscous polymer processing. The rheological and energy-storing performance were systematically studied. It can be seen that high PVA content results in more pores and larger grain sizes that will deteriorate the breakdown strength of ceramics. The highest breakdown strength reached 420 kV/cm while the concentration of PVA was 5 wt%. The mechanism of grain sizes on breakdown strength is studied by electrical tree simulation based on COMSOL. Viscous polymer processing with proper PVA content is very effective in generating dense and homogenous structures. Finally, the ceramic with 5 wt% PVA possesses a high density of up to 4.41 J/cm³ and an efficiency of about 84.21% at 420 kV/cm. Simultaneously, this ceramic improved stability of both temperature (30–150°C) and frequency (1–300 Hz) at 350 kV/cm, while the η kept above 90% and W_rec exceeding 3.6 J/cm³.