非晶态界面微区构建：介质极化与耐压能力协同的共性问题

To optimize energy storage performances, it is essential to develop advanced energy dielectric materials with high dielectric polarization, large dielectric breakdown and low dielectric hysteresis loss. However, the two parameter, dielectric polarization and breakdown, exhibits close relationship due to the improvement of one parameter at the expense of the other. A complete synergy between dielectric polarization and dielectric breakdown should be considered for the future energy materials. It is well-known that both glass- and polymer-based materials show very excellent electrical breakdown due to random network structure in non-crystalline solid materials compared with polycrystalline ceramics. Here, an isomeric material will be designed to construct an amorphous interface microregion to increase dielectric breakdown by non-crystalline compositions and dielectric polarization by high permittivity compositions. Based on Bi-based dielectrics, we will systematically investigate reaction kinetics of amorphous structure for forming coexistence of polycrystalline and amorphous compositions, evaluate dielectric breakdown by constructing amorphous interface microregion and their dependence of physical response on external environment (electric field and temperature). Finally, we will further discuss the effects of non-crystalline composition on the energy storage performances of dielectric materials.

为提高介质的储能性能，要求介质材料具有大的极化特性、高的耐压强度和低的极化损耗。而介质极化与耐压能力在储能介质中是矛盾的两个重要参数。要改善介质储能性能，就需要解决介质极化与耐压能力协同提升的科学问题。由于非晶态的无规则网络结构，与晶态结构陶瓷相比，具有非晶结构的玻璃和聚合物具有更优异的耐压特性。以陶瓷介质为研究对象，本项目利用非晶介质的耐高压特性和介质的高极化特性，设计一种同质异构型复合结构，即同一组成介质以非晶态和多晶态结构共存，以期达到介质极化与耐压能力协同提升的目的。项目以中等介电常数Bi基组成为研究对象，系统开展非晶结构反应动力学研究，立足非晶微区构建与电性能关系，观测介质在外界扰动（电、温度等）下的物性响应，探讨介质极化与耐压协同的共性问题，进一步阐明非晶结构与储能性能的物理机制。

具有大的极化特性、高的耐压强度和低的极化损耗是介质材料获得高储能密度和效率的重要前提，而介质极化与耐压能力在储能介质中是相互制约的两个重要参数。项目基于非晶相的高耐压和多晶相的大极化特性，致力于解决介质极化与耐压能力协同提升的问题。项目获得了“非晶-多晶”结构共存的陶瓷薄膜制备技术，开展了非晶微区构建与电性能关系，研究了相结构、极化特性、击穿强度及界面效应之间的相互关联性，探索了极化饱和延迟效应、界面效应与耐压强度、极化与耐压强度的协同关联性与储能性能的耦合关系；宏观上阐明了“非晶-多晶”微区的存在能显著提高储能性能，获得了介质极化与耐压协同提升，为介质极化与耐压能力两个重要参数如何产生协同效应提供了科学依据。