Research On Preparation And Energy Storage Properties Of Strontium Titanate Based Ceramics

Ceramic capacitors can be widely used for pulsed power systems due to their fast charge-discharge rate,large dielectric constant,wide range of working temperature and long cycle life.Most of ceramic capacitors that used for pulsed power systems are lead based materials at present.The toxic nature of lead would cause a series of environment and life problems.Whereas the lead-free ceramics possess small energy storage density and low energy storage efficiency due to low electric breakdown strength or small maximum polarization.Meanwhile,the lead-free ceramics at present are difficult to achieve the demands of miniaturization and integration for electronic components.Therefore,the purpose of this study is to enhance the energy storage performance of lead-free ceramics.Strontium titanate based ceramics were prepared using traditional solid-state sintering and tape-casting method.The related performance of these materials were studied in detial.The?1-x?SrTiO₃-x(0.65BaTiO₃-0.35Bi_0.5Na_0.5TiO₃)?denoted as?1-x?ST-x?BT-BNT??and?1-x?SrTiO₃-x(0.95Bi_0.5Na_0.5TiO₃-0.05BaAl_0.5Nb_0.5O₃)?denoted as?1-x?ST-x?BNT-BAN??energy storage ceramics were fabricated using traditional solid-state sintering method.The results reveal that BT-BNT and BNT-BAN formed perovskite solid solution with ST,respectively.The temperature of maximum dielectric constant?T_m?shifts towards high temperature and the maximum polarization(P_max)increases gradually with increasing addition of BT-BNT and BNT-BAN.Meanwhile,all the samples possess slim polarization electric field?P-E?loops.The?1-x?ST-x?BT-BNT?energy storage ceramics exhibit outstanding energy storage performance with x=0.3.The charge energy storage density?energy storage density,W?is 1.54 J/cm³,the discharge energy storage density(recoverable energy storage density,W_rec)is 1.40 J/cm³and the energy storage efficiency???is 91%.Whereas the?1-x?ST-x?BNT-BAN?energy storage ceramics exhibit outstanding energy storage performance(W=2.46 J/cm³,W_rec=1.89 J/cm³,?=77%)with x=0.5.The?1-x?SrTiO₃-x(Bi_0.5(Na_0.82K_0.18)_0.5Ti_0.96Zr_0.02Sn_0.02O₃)?denoted as?1-x?ST-xBNKTZS?energy storage ceramics were fabricated via traditional solid-state sintering method.The?1-x?SrTiO₃-x(Bi_0.48La_0.02Na_0.48Li_0.02Ti_0.98Zr_0.02O₃)?denoted as?1-x?ST-xBLNLTZ?energy storage ceramics were fabricated using traditional solid-state sintering method and tape-casting method,respectively.The results reveal that BNKTZS and BLNLTZ formed perovskite solid solution with ST,respectively.Average grain size and dielectric constant of the samples tend to increase with increasing addition of BNKTZS and BLNLTZ.The?1-x?ST-xBNKTZS energy storage ceramics that prepared by traditional solid-state sintering method exhibit outstanding energy storage performance(W=1.68 J/cm³,W_rec=1.45 J/cm³,?=86%)with x=0.4.The?1-x?ST-xBLNLTZ energy storage ceramics that prepared by traditional solid-state sintering method exhibit outstanding energy storage performance(W=1.77 J/cm³,W_rec=1.56 J/cm³,?=88%)with x=0.2.Whereas the?1-x?ST-xBLNLTZ energy storage ceramics that prepared by tape-casting method exhibit outstanding energy storage performance with x=0.1.The value of W reaches up to 3.04 J/cm³,the value of W_rec is 2.59 J/cm³ and the value of?is 85%.The?1-x?SrTiO₃-x(0.94Bi_0.54Na_0.46TiO₃-0.06BaTiO₃)?denotedas?1-x?ST-x?BNT-BT??energy storage ceramics were fabricated via traditional solid-state sintering method.The?ST+0.5 wt%Li₂CO₃?/?BNT-BT??denoted as STL/?BNT-BT??multilayer energy storage ceramics were fabricated using tape-casting method.The results reveal that the?1-x?ST-x?BNT-BT?energy storage ceramics exhibit outstanding energy storage performance(W=2.36J/cm³,W_rec=1.88 J/cm³,?=79%)with x=0.5.Obvious layer structure can be observed for STL/?BNT-BT?multilayer energy storage ceramics.Meanwhile,the STL/?BNT-BT?multilayer energy storage ceramics have both the performance of ST and BNT-BT ceramics and exhibit outstanding energy storage performance(W=3.55 J/cm³,W_rec=2.41 J/cm³).The?SrTiO₃+0.5 wt%Li₂CO₃?/(0.93Bi_0.5Na_0.5TiO₃-0.07Ba_0.94La_0.04Zr_0.02Ti_0.98O₃)?denoted as STL/?BNT-BLZT??multilayer energy storage ceramics and?1-x?ST-x?BNT-BLZT?energy storage ceramics were fabricated using tape-casting method.The results reveal that the value of P_max can be enhanced from 3.89?C/cm² to 29.04?C/cm² rapidly with increasing the electric field from20 kV/cm to 294 kV/cm for STL/?BNT-BLZT?multilayer energy storage ceramics.Whereas the value of P_r is only 3.63?C/cm².Therefore,W and W_recec can be reached up to 3.67 J/cm³ and 2.72 J/cm³,respectively.The value of?is74%.The?1-x?ST-x?BNT-BLZT?energy storage ceramics possess perovskite structure.Meanwhile,the value of Pmax enhanced obviously with increasing addition of BNT-BLZT.Optimal energy storage performance(W=3.33 J/cm³,W_rec=2.83 J/cm³,?=85%)can be obtained with the composition of x=0.2 as well as the maximum electric field reached up to 320 kV/cm.In addition,temperature stability and frequency stability of both energy storage density and energy storage efficiency exist in wide temperature and frequency range respectively for?1-x?ST-x?BNT-BLZT?energy storage ceramics.