聚醚酰亚胺纳米复合电介质中指数分布陷阱电荷跳跃输运对储能性能的影响

Effect exponentially distributed trapped charge jump transport on energy storage performance in polyetherimide nanocomposite dielectric

目前常见聚合物电介质电容器的储能性能在高温下会急剧劣化,难以满足航空航天和能源等领域的需求.为提高介质高温储能性能,常掺杂纳米填料对电介质改性,通过改变电介质内部陷阱参数来调控电荷输运过程,但其内部陷阱的能级和密度与储能性能间的定量关系仍需进一步研究.本文构建线性聚合物纳米复合电介质中指数分布陷阱电荷跳跃输运的储能与释能模型并进行了仿真.纯聚醚酰亚胺在150℃的体积电阻率和电位移矢量-电场强度回线的仿真结果与实验符合,证明了模型的有效性.不同陷阱参数纳米复合电介质的仿真结果表明,增大总陷阱密度和最深陷阱能级,会降低载流子迁移率、电流密度和电导损耗,提升放电能量密度和充放电效率.在150℃和550 kV/mm外施场强下,1.0 eV最深陷阱能级和1×10^(27) m^(-3)总陷阱密度的纳米复合电介质放电能量密度和充放电效率分别为4.26 J/cm^(3)和98.93%,相比纯聚醚酰亚胺提升率分别为91.09%和227.58%,显著提升了高温储能性能.本研究为耐高温高储能性能电容器的研发提供了理论和模型支撑.

With the development of science and technology,polymer dielectric capacitors are widely used in energy,electronics,transportation,aerospace,and many other areas.For polymer dielectric energy storage capacitors to remain effective in practical applications,excellent charge and discharge performance is essential.However,the performance of the common polymer dielectric capacitors will deteriorate rapidly at high temperature,which makes them fail to work efficiently under worse working conditions.Dielectric trap energy levels and trap densities increase when nanoparticles are incorporated into the dielectric.The change in trap parameters will affect carrier transport.Therefore,the high temperature energy storage performance of polymer nanocomposite dielectric can be improved by changing the trap parameters to regulate the carrier transport process.However,the quantitative relationship between trap energy level and trap density and the energy storage properties of nanocomposite dielectric need further studying.In this paper,the energy storage and release model for exponentially distributed trapped charge jump transport in linear polymer nanocomposite dielectrics is constructed and simulated.The volume resistivity and electric displacement-electric field loops of pure polyetherimide are simulated at 150℃,and the simulation results match the experimental results,which demonstrates the validity of the model.Following that,under different temperatures and electric fields,the current density,electric displacement-electric field loops,discharge energy density and charge-discharge efficiency of polyetherimide nanocomposite dielectric are simulated by using different trap parameters.The results show that increasing the maximum trap energy level and the total trap density can effectively reduce the carrier mobility,current density and conductivity loss,and enhance the discharge energy density and the charge-discharge efficiency of the nanocomposite dielectric.On condition that temperature is 150℃and applied electric field is 550 kV/mm,the polyetherimide nanocomposite dielectric with a maximum trap energy level of 1.0 eV and a total trap density of 1×10^(27) m^(-3),has 4.26 J·cm^(-3) of discharge energy density and 98.93%of energy efficiency.Compared with pure polyetherimide,the rate of improvement is 91.09%and 227.58%,respectively.The energy storage performance under high temperature and high electric field is obviously improved.It provides theoretical and model support for the research and development of capacitors with high temperature resistance and energy storage performance.