Study On The Dielectric And Energy Storage Property Of Lead-free Antiferroelectric/Polymer Composites

As one of the most important electronic components in power and electronic information systems,film capacitors are widely used in circuits to achieve functions such as blocking,coupling,bypass,filtering,and energy conversion.Compared with batteries,electrochemical capacitors,etc.,film capacitors have high electric field strength,fast discharge speed,and high storage density.They are especially suitable for discharge capacitors that need to release a large amount of electrical energy in a short time,such as inverters and electric vehicles.The core of the film capacitor's ability to store and release energy is its internal dielectric materials.Studies have found that the combination of inorganic ceramics and polymers can increase the dielectric constant of dielectric composites,thereby improving the performance of energy storage.In this study,by preparing lead-free antiferroelectric/polymer-based composites,the influence of lead-free antiferroelectrics in different polymers and different structural designs on the dielectric energy storage performance of composites was studied.The main contents are as follows:(1)The influence of the addition of BNT-x BMN ceramic particles with different phase structures on the dielectric energy storage performance of composite materials was studied.The study found that the residual polarization of the composite materials was lower when the BMN composition is 0.08 than 0.04 and 0.052,the energy storage desity reached 12.11 J/cm³at 500 MV/m,and the energy storage sufficiency reached64.32%.(2)The influence of lead-free antiferroelectric(Na_0.5Bi_0.5)Ti O₃-_0.04(Sr_0.7Bi_0.2)Ti O₃(NBT-SBT)on the dielectric energy storage performance of composite materials was studied.The study found that 4 wt.%NBT-SBT/PVDF composite achieved a maximum energy storage density of 15.3 J/cm³at the maximum electric field(500MV/m),and exhibits good fatigue resistance in 10⁵cycles of testing.(3)The dielectric energy storage properties of NBT-SBT/ABS composite materials were studied at room temperature and high temperature respectively.The breakdown field strength of 4 wt.%NBT-SBT/ABS composite at room temperature reached as high as 550 MV/m,and the maximum energy storage density was 13.9J/cm³;at 120 ?,4 wt.%NBT-SBT/ABS achieved 11.19 J/cm³.(4)The dielectric energy storage performance of BNNS/ABS composites with different mass fractions was studied at room temperature and 120 ?.Research showed that BNNS with wide band gap insulation layer effectively improves the breakdown field strength of composite materials.The breakdown field strength of 4wt.%BNNS/ABS material at room temperature reached 625 MV/m,which is 25%higher than the breakdown field strength of ABS(500 MV/m),and the energy storage density reached 14.57 J/cm³;At 120 ?,the breakdown field strength reached 600MV/m,and the energy storage density was 12.83 J/cm³.On this basis,two kinds of“sandwich”structure composites were prepared by hot pressing.One type of NBT-SBT/ABS is the outer layer,BNNS/ABS is the middle layer(defined as SBS type in this article),the other BNNS/ABS is the outer layer,and the middle layer is NBT-SBT/ABS(defined as BSB in this article).The breakdown strength of the SBS type was as high as 650 MV/m,and the ultra-high energy storage density was 18.29J/cm³.At 120 ?,the dielectric energy storage performance was relatively stable,the energy storage density was 15.01 J/cm³.In addition,the two laminated materials exhibited excellent fatigue resistance in 10⁶ cycles of testing.