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

Abstract

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 (Udischarge) and discharge/charge efficiency (Eeff). 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 μm to 19 μm, resulting in improvement of maximum discharge energy density (Umax) from 1.29 J/cm3 to 4.00 J/cm3. Linear relationship between power index of dielectric thickness and breakdown strength was observed, which could be described as BDS∝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.