铌酸盐反铁电/弛豫铁电复合材料的界面耦合、极化增强机理及储能特性

High dielectric permittivity, high power density and good temperature stability of the relaxor-ferroelectric materials are received much attention in energy storage and pulsed power applications. However, the low energy storage density has become a bottleneck restricting the relaxor-ferroelectric extensive applications in energy storage systems. In this project, the alkali niobate-based anti-ferroelectric/relaxor-ferroelectric composites are designed to improve the energy storage properties, and the influence of interface coupling and anti-ferroelectric polarization enhancement on the energy storage properties were studied. Firstly, the core-shell, 0-3 and 2-2 type anti-ferroelectric/relaxor-ferroelectric composites are prepared, and the compositional gradients, structure, morphology and stress state of interface between anti-ferroelectric and relaxor-ferroelectric phases are explored. Secondly, the interfacial coupling polarization and the tunneling mechanism of carrier under strong electric field are revealed. Also, the polarization enhancement mechanisms of the phase transition of the anti-ferroelectric under strong electric field are elucidated. Finally, the effect of the configuration, size and morphology to the energy storage characteristics are achieved, and the theoretical model between energy storage performance and composite configuration and shape parameters are established. The successful realization of this project will provide a technological and theoretical prototype for the design and preparation of high-performance energy storage materials.

弛豫铁电储能材料具有高介电常数、高功率密度和良好的温度稳定性，在能量储存和脉冲功率器件领域应用前景广阔，但低储能密度成为其大规模应用的瓶颈。本项目以铌酸盐体系反铁电/弛豫铁电复合材料为研究对象，拟通过界面耦合及反铁电相变极化增强的途径来提高储能特性。首先研究核-壳型、0-3型及2-2型反铁电/弛豫铁电复合材料的构造工艺，并探索两相复合界面的成分梯度、结构、形貌及应力状态；进而研究强电场下两相界面耦合极化和载流子的隧穿机理，阐明反铁电体相变对复合材料的极化增强机理；最后揭示复合构型、尺寸与形貌对复合材料的介电储能特性的影响规律，建立储能性能与复合构型及形状参数之间的理论模型，为新型高性能储能材料的设计、制备奠定基础。

电介质电容器功率密度高、充放电速度快、适用于高温极端环境，在脉冲功率器件、新能源汽车等领域展现出巨大的应用前景。然而，其较低的储能密度成为阻碍储能器件小型化、微型化的瓶颈。本项目通过构建铌酸盐体系反铁电/弛豫铁电复合材料，以界面耦合及反铁电相变极化增强的途径来提高储能特性。研究掺杂组分对铌酸钾钠（KNN）基陶瓷弛豫性的影响，寻找出介电性能温度稳定的组分和最佳的工艺；探究铌酸钾钠铁电材料的晶粒尺寸与相界对压电催化性能的影响，构建晶粒尺寸、相结构与铁电极化性能之间的关系模型；系统地研究了弛豫铁电与反铁电复合陶瓷制备工艺，发现晶界区的高阻层可大大抑制电子和缺陷离子（主要是氧空位）的长程迁移，进而有效地提高复合陶瓷的击穿电场；探究两相界面耦合和极化性能增强机理，揭示复合构型以及微结构参数（组分、结构、形状、大小以及应力状态）对复合材料体系的介电储能性能的影响规律。本项目的研究可为脉冲储能电容的材料组成、制备工艺及微结构设计策略提供重要理论支撑。