Lead Sodium Niobate Glass-Ceramic Dielectrics and Internal Electrode Structure for High Energy Storage Density Capacitors

Na₂O-PbO-Nb₂O₅- SiO₂ glass-ceramic dielectrics and internal electrode structures were investigated to improve the general energy storage density of capacitors. This work was brought out by the motivation of elimination of structural flaws and pores remaining in dielectrics and at electrode/dielectric interfaces, which are the main causes of low dielectric strength and low energy storage density of the traditional sintered dielectric capacitors. The combination of pore-free glass-ceramic dielectrics and series internal electrodes was adapted in the design of high energy storage density capacitors (HESDCs). The results show that the dielectric properties and the breakdown strength of glass-ceramics could be optimized through appropriate crystallization profiles, which could lead to an energy storage density of up to 17 J/cm³ for glass-ceramics crystallized at 850degC for 3 h. The series multilayer capacitors could bear a rather higher electric field compared with the traditional ones without internal electrodes, and the dielectric strength could be further improved when the internal electrodes are made of sputtered gold films and printed paste. As a result, an overall energy storage density of about 8 J/cm³ has been achieved for the capacitor with internal electrodes made of gold film and screen-printed paste when the 850degC-crystallized glass-ceramic dielectric was used.