Research On Dielectric Properties Of PLZST-based Ceramics For Pulsed Energy Storage Capacitors

Ceramic energy storage capacitor can discharge with instantaneous high current and high voltage.It has an irreplaceable position in energy storage pulsed power devices.However,it is far from meeting the requirements of miniaturization and integration in energy storage devices because of its low energy storage density.The high energy density pulse capacitors,which has the characteristics and advantages of traditional batteries and capacitors,is an important trend in the future.The core of the high energy density pulse capacitors is the development of high energy density ceramic media.So it is of great significance for the development of high energy density ceramic dielectric materials.In this paper,the development trend of various dielectric materials is introduced.And their advantages and disadvantages are analysed.The anti-ferroelectric?Pb0.97La0.02??Zr0.5Sn0.44Ti0.06?O₃?PLZST?ceramics are selected as the research object.In order to improve the breakdown electric field of the anti-ferroelectric PLZST based material,the doping method of?1-x?PLZST-xBiYO₃?PLZST-BY?is put forward by using the principle of ion doping.PLZST-BY ceramics are prepared by conventional solid-state method.The results show that BY doping raises the sintering temperature of PLZST,and the addition of BY has little effect on the frequency stability of PLZST.Because Bi3+ and Y3+ doping concentration increases,the defects of the second phase of pyrochlore phase increases.With the doping amount of BY,the dielectric constant increases and then decreases.The doping reduces the AFE-FE phase transition electric field of PLZST.It indicates that the doped PLZST has higher energy storage density under the same electric field.With the addition of BY doping,the density of the ceramics increases,and the breakdown electric field of the ceramics increases obviously.In the sample doped with x=0.3,the breakdown electric field is up to22.1kV/mm.In the x=0.1 doped samples,the breakdown electric field reaches14.6kV/mm,the energy storage efficiency is 83.3%,the energy density can reach0.80J/cm3,nearly 2.7 times higher than the pure PLZST bulk ceramics.In this paper,Alkali free Ba-B-Al-Si glass is selected because of its relatively high dielectric constant,high-pressure resistance and low loss.Ba-B-Al-Si glass powder is prepared by high temperature melting method,and glass ceramics with glass phase structure were prepared by mixing with PLZST matrix.Ba-B-Al-Si glass has a high breakdown field strength ¹2MV/cm,and PLZST ceramic composite is conducive to improve the breakdown strength of ceramics.Ba-B-Al-Si glass reduces the sinteringtemperature of ceramics.The results show that the Ba-B-Al-Si glass is effective for the enhancement of the breakdown electric field,and the breakdown electric field in the 7wt% doped sample reaches 13.69kV/mm.However,there is mutual diffusion between two-phase Ba-B-Al-Si glass and ceramic,resulting in improving thermionic polarization loss,and reducing the polarization of doped ceramics.However,energy density and energy efficiency decreased.MLCC ceramic tape was prepared with PLZST as medium by casting,isostatic pressing.In order to explore the energy storage potential for PLZST,the dielectric properties of PLZST single layer with different thickness is analysed.The sintering process is explored in PLZST film by tape casting.The total energy storage density of the tape is as high as 2.01J/cm³.