Enhanced energy storage performance and theoretical understanding of the dielectric breakdown behavior for Ba0.4Sr0.6TiO3/Al2O3 ceramics

Ba0.4Sr0.6TiO3 (BST) ceramics with Al2O3 additives are synthesized by spark plasma sintering (SPS) to enhance the energy storage density. Numerical simulations based on a stochastic model are carried out to further understand the breakdown behaviors in BST/Al2O3 ceramics. Greatly enhanced dielectric breakdown strength from 210 kV/cm to 300 kV/cm is realized in BST-1 %Al2O3 ceramics due to the optimized microstructure and the high insulation of Al2O3 additives. The maximum energy storage density of 1.69 J/cm3 is obtained, which is 1.4 times larger than pure BST ceramics. Based on the simulations, it is found that the discharge channels try to bypass the particles due the high critical breakdown field of Al2O3, which will extend the breakdown path in ceramics and contribute to the improved breakdown strength. However, after exceeding a certain amount of Al2O3 addition, the interface effect will be predominant and lead to the degradation of breakdown strength.