Preparation. Structure And Properties Of Barium Strontium Titanate-Based High Energy Storage Ceramics

Capacitors have received more and more attention for energy storage because of their advantages of fast responding, light and environmentally-friendly. Dielectrics are key materials for energy storage capacitor. Ceramic dielectrics possess high dielectric constant, long life, high mechanical strength, and can be used in board temperature range and harsh environments. However, the energy density of ceramics is lower than that of polymers because of their low dielectric breakdown strength. In order to improve the energy storage density of ceramic dielectrics, barium strontium titanate-based ceramics with high energy storage density were prepared by spark plasma sintering, and their properties and microstructure were systematically investigated.Dense ceramics of Ba0.3Sr0.7TiO3and Ba0.4Sr0.6TiO3were obtained by spark plasma sintering (SPS) and thermal treatment. By using SPS, the optimal sintering temperature was decreased from1400℃to1000℃. Both ceramics present uniform and dense microstructure, and the average grain sizes of Ba0.3Sr0.7TiO3and Ba0.4Sr0.6TiO3ceramics are880and1050nm respectively. BST ceramics sintered by SPS were optically transparent, and the transmittances at633nm for both samples with a thickness of0.3mm are higher than74%.It was found that the BST ceramics prepared by SPS have a small residual polarization and high dielectric breakdown strength, which results in the significant improvement of energy storage density. The energy storage densities of Ba0.3Sr0.7TiO3and Bao.4Sro.6Ti03ceramics are1.13J/cm3and1.20J/cm3respectively. The temperature and frequency stability for energy storage of BST ceramics prepared by SPS is better than that of the ceramics prepared by the standard solid state method.Addition of glass leads to the decrease of grain size, dielectric constant and dielectric loss. The energy storage density of BST37-GO3, BST46-G03, BST37-G10, BST46-G10was improved to0.81J/cm3,1.23J/cm3,1.14J/cm3,1.00J/cm3, respectively, because of the remarkable enhancement of breakdown strength and the decrease of residual polarization. Meanwhile, the temperature and frequency stability for energy storage of the samples was significantly improved.