Effects of dielectric thickness on energy storage properties of surface modified BaTiO3 multilayer ceramic capacitors

Surface modified BaTiO3 were synthesized by coating BaTiO3 particles of 50/230 nm average grain size with 3 wt% Al2O3 and 1 wt% SiO2 (BTAS5/BTAS1). Multilayer ceramic capacitors (MLCC) were fabricated via two-steps sintering method. After sintering, average grain size (G) of BTAS5/BTAS1 MLCC slightly increased to 106/273 nm. Compared to BTAS1, BTAS5 MLCC with finer grains possessed higher breakdown strength (BDS), discharge energy density (U-discharge) and discharge/charge efficiency (E-eff). Moreover, great enhancement of BDS from 265 kV/cm to 651 kV/cm was obtained as dielectric thickness (D) of BTAS5 MLCC decreased from 68 mu m to 19 mu m, resulting in improvement of maximum discharge energy density (U-max) from 1.29 J/cm(3) to 4.00 J/cm(3). Linear relationship between power index of dielectric thickness and breakdown strength was observed, which could be described as BDS proportional to D-0.397. The results matched the model of Forlani and Minnaja well, with regard to the volume effects. Because of their low-cost, easily fabrication, lead-free, enhanced breakdown strength and improved discharge energy density, surface modified BaTiO3 multilayer ceramic capacitors can provide realistic solutions for high power energy storage applications. (C) 2019 Elsevier B.V. All rights reserved.