NaNbO3基无铅储能介质陶瓷研究进展OA北大核心CSTPCD

Dielectric capacitors are one of the most important components in electrical equipment and electronic devices,and have attracted recent attention in the fields of new energy vehicles,advanced propulsion weapons,renewable energy storage,high-voltage transmission,and medical defibrillators.Dielectric capacitors have ultra-short charge and discharge time,ultra-high power density and high operational safety,compared with electrochemical capacitors such as batteries,fuel cells and supercapacitors.However,the low energy storage density of dielectric capacitors limits their wide application.Therefore,it is necessary to develop dielectric capacitors with a high temperature and a high energy density. NaNbO3(NN)-based ceramic material is considered as one of the most potential dielectric energy storage materials because of its wide band gap,lower cost and high polarization.However,there are still some problems in the application of NN-based ceramic materials,such as low energy storage density and energy storage efficiency,and poor temperature stability.In order to optimize the energy storage performance of NN-based ceramics,phase structure regulation,micro-morphology optimization,doping modification(for A-site,B-site,A/B-site co-doping)are used to improve the energy storage density,efficiency,and frequency/temperature stability.These optimization strategies provide opportunities for the application of NN-based ceramics. NN-based ceramics have a complex phase structure,and pure NN cannot obtain double hysteresis loops at room temperature,which is attributed to the irreversible transition between the antiferroelectric P(AFE P)and ferroelectric Q(FE Q)phases.The AFE P phase can be stabilized,and the double hysteresis loop with a reversible phase transition can be obtained,improving the energy storage density and energy storage efficiency via reducing the tolerance factor.In terms of microstructure optimization,advanced sintering process,suitable sintering additives and preparation process can further improve the energy storage performance of NN-based ceramics.The advanced sintering process can optimize the microstructure,adjust the grain size and oxygen vacancy concentration to improve the energy storage performance.For instance,compared with Na0.7Bi0.1Nb0.9Ta0.1O3 ceramic prepared via conventional sintering,the energy storage efficiency of the ceramic sample prepared via spark plasma sintering(SPS)increases from 81.1%to 90.5%.Adding suitable sintering additives can form a liquid phase,and then improve the densification process of ceramics.Also,the addition of sintering additives can reduce the sintering temperature and play the role of refining the grains,which is conducive to increasing the resistance of the ceramics and thus increasing the breakdown field.For MnO2-doped 0.95NaNbO3-0.05SrSnO3(NN5SS)ceramic,the energy storage density can be increased by nearly 14 times,compared to undoped NN5SS.The advanced preparation process can improve the density and electrical uniformity,thus improving the energy storage performance.The viscous polymer processing(VPP)can increase the energy storage density of 0.84 NaNbO3-0.06 BiFeO3-0.1 SrTiO3 ceramics from 2.7 J/cm3 to 5.29 J/cm3,compared to conventional solid phase sintering. The energy storage performance of NN-based ceramic can be improved via doping modification.Doping modification can introduce relaxation antiferroelectric properties,showing that long-range ordered antiferroelectric domains are broken to form micron-sized or nano-sized domains,which have a rapid response to the applied electric field,reduce the polarization lag between applied or discharged electric fields,and thus obtain a superior energy storage performance.Also,the solution of the second or third component can introduce relaxation characteristics,and the TB and Tm temperature regions with nanodomains and polar nanoregions can be adjusted to room temperature in the NN-based system,showing the relaxation characteristics and improving the energy storage performance. Summary and prospects The energy storage performance can be improved to a certain extent by means of phase structure regulation,micro-morphology optimization,doping modification,etc..However,the harsher application environment requires a higher energy storage performance(i.e.,Wrec>10 J/cm3,η>90%).The future development aspects of NN-based energy storage ceramics involve 1)raw material preparation,i.e.,wet chemical method(such as hydrothermal method,sol-gel method,self-spreading method,etc.)and high-energy ball milling method are used to reduce the particle size of the powder to further improve the electrical performance;2)sintering process,i.e.,advanced preparation processes(such as SPS,flash sintering,cold sintering,hot press sintering,etc.)are used to improve the energy storage performance while greatly reducing energy consumption;3)molding process,i.e.,the process of rolling film,casting and cold isostatic pressing are used to further optimize the microstructure and improve the energy storage performance;4)theoretical research,i.e.,combined with advanced in-situ characterization techniques(such as in-situ high resolution TEM,micro-infrared,etc.)and theoretical calculations(such as first-principles,phase field simulation,etc.),a relationship between process-structure-performance is further explored,and new theories and mechanisms are proposed;and 5)device preparation,i.e.,the device with superior energy storage performance and high stability dielectric materials needs to be developed.