Energy Storage Behavior And Pulsed Charging-discharging Performance Of Bi_0.5Na_0.5TiO₃-based Ferroelectric Materials Driven By Low Electric Field

In this study,the energy storage performance of BNT-based materials are tailored by employing solid solution modification and construction of A-and B-site ion disorder to realize the low electric field-driven high energy storage property,which can effectively promote the practical applications of dielectric capacitors.We demonstrate that such drawback can be effectively resolved by using Sr0.7Bi0.2TiO3(SBT)to partially replace relaxor ferroelectric 0.76(Bi0.5Na0.5)TiO30.24NaNbO3(BNT-NN-xSBT)In this study,a high recoverable energy storage density(Wrec～3.12J/cm3)and favorable efficiency(η～75.3%)are achieved in the BNT-NN0.1 SBT ceramic under a low electric field of 200 kV/cm,which is superior to that of most previously reported dielectric ceramics under the same electric field level.Good temperature stability(25-120℃),moderate frequency dependence(1-500Hz),and excellent fatigue resistance(up to 105 cycles)are also realized.More interestingly,the indicated ceramics perform high power density(PD～36.40 MW/cm3)and fast discharge time(t0.9～0.149μs)with remarkable temperature endurance.By applying the solid solution modification strategy,a series of 0.6BNT-0.4(Sr11.5xBix)TiO3 ceramics were successfully prepared.In order to further optimize the energy storage behavior including the low electric field-driven high energy density and efficiency,considering the solution that bismuth component plays an important role in the enhancement of the maximum polarization due to the hybridization between the O22p and Bi3+6p orbitals,we have adjusted the Sr/Bi ratio in the BNT-SBT ceramics.A novel lead-free ceramics 0.6BNT-0.4Sr0.775Bi0.15TiO3 composite is investigated in this study,which achieves a large energy storage density(Wrec～2.41 J/cm3)and a high efficiency(η～87.5%)under a low electric field of 190kV/cm.Additionally,good temperature stability(20-120℃),excellent frequency dependence and fatigue stability were achieved.More importantly,0.6BNT-0.4Sr0.775Bi0.15TiO3 ceramics possess a giant power density(PD～51.4 MW/cm3),a large current density(CD～934A/cm2 and a ultrafast discharge time(t0.9～77ns).Furthermore,0.6BNT-0.4Sr0.775Bi0.15TiO3 ceramics also exhibit outstanding temperature stability and fatigue dependence during the process of pulsed charging-discharging.By constructing the morphotropic phase boundary(MPB)and introducing B-site disorder,two series of ceramics including 0.9[0.7BNT-0.3ST]-0.1Bi(Me0.5Sn0.5)O3 and 0.9[0.7BNT-0.3ST]-0.1Bi(Me2/3Nbi/3)O3(Me=Ni;Mg;Zn;Co)were successfully prepared.The ergodic relaxation property of the ceramics was effectively enhanced,promoting the optimization of energy storage behavior under a low electric field.Among them,Sn-Mg,Nb-Ni and Nb-Mg components show enhanced energy storage characteristics.In detail,Sn-Mg component achieves a large energy storage density(Wrec～3.46 J/cm3)and a high efficiency(η～77.8%)under a low electric field of 240kV/cm,Nb-Ni component achieves a large energy storage density(Wrec～2.78 J/cm3)and a high efficiency(η～90%)under a low electric field of 200kV/cm,and Nb-Mg component achieves a high energy storage density(Wrec～3.07 J/cm3)and a high efficiency(η～83%)under a low electric field of 230kV/cm.Additionally,good temperature stability(20-120℃),excellent frequency dependence and fatigue stability were achieved in the above mentioned ceramics.In addition,the charge-discharge performance of capacitor were also investigated.In detail,the Sn-Mg component performs high power density(PD～49 MW/cm3)and fast discharge time(t0.9～89ns)with remarkable temperature endurance,the Nb-Ni component performs high power density(PD～65.6MW/cm3)and fast discharge density(Wd～l.15J/cm3),and Nb-Mg component possesses a giant power density(PD～63MW/cm3)and a ultrafast discharge time(t0.9～68ns).