高纵宽比核壳结构钛酸锶钡-聚合物复合材料的制备及界面特性研究

Dielectric electrical storage (capacitor) is regarded as the most prospects for energy storage due to its high power density and long cycle life; however, the development of it is slow, mainly limited by its relative low energy density. Ceramics and polymer composites with high aspect ratio and core-shell structured filler show great potential, and are expected to become a new generation of high energy density materials for pulse capacitor. In the current project, BST fibers are prepared through sol-gel, VPP and electrospinning processing; the core-shell structured ceramic-polymer composites are obtained by sol precipitation and surface modification technology, and the energy storage density is finally optimized; the effect of fiber grain size and aspect ratio on energy density of composites is studied, and the size effect in the composites is revealed; in-situ and dynamic analysis of the interfacial morphology, charge distribution, the polarization response of the filler and the matrix are carried out by means of the piezoresponse force microscopy, and the mechanism of the polarization response in micro area of the composite is established; the mechanical behaviors of the interface are carried out through macro and micro mechanical test, and the influence laws of interface properties on the mechanical properties of the composites are revealed; based on the construction principle of laminated capacitor, new structures of polymer composites are explored and new technology and new preparation processing for the corresponding polymer composites based on the new structures are developed. This investigation is expected to promote the applications of core-shell structure materials in energy storage field, and greatly promote the development of pulse capacitors with higher energy density.

介电存储因具有大的功率密度、长的循环寿命，被视为当前最具前景的能量存储技术，但其发展较缓，主要受限于较低的能量密度。高纵宽比核壳结构陶瓷-聚合物复合物展现了较大潜力，可望成为新一代高储能密度脉冲电源电容器用材料。本项目拟采用溶胶凝胶、VPP、静电纺丝制备BST纤维，经溶胶沉淀、表面修饰工艺获得核壳结构陶瓷-聚合物复合物并优化其储能密度；研究复合物中纤维晶粒尺寸和纵宽比对储能密度的影响，揭示复合物中的尺寸效应；借助压电力显微镜对界面形貌、电荷分布、填料与本体的极化响应进行原位、动态分析，建立复合物微区极化响应机制和相关模型；通过宏观、微观力学测试研究复合物界面力学行为，揭示界面属性对复合物力学性能的影响规律；依据叠层电容器构造原理，探索陶瓷-聚合物复合物的新型结构，并据此发展相应复合物的制备新技术与新工艺。本研究可望促进核壳结构材料在能量存储领域的应用，并推动高储能密度脉冲电源电容器的发展。

介电储能因具有大的功率密度、长的循环寿命，被视为最具前景的能量存储技术，但发展较缓，主要受限于低的能量密度。核壳结构陶瓷、高纵宽比陶瓷-聚合物复合物展现出较大潜力，可望成为新一代高储能密度脉冲电源电容器用介质材料。本项目探索了陶瓷及陶瓷-聚合物复合物的新结构，并据此发展了制备新技术，可望促进介质材料在电能存储领域的应用，尤其推动高储能密度脉冲电源电容器的发展。项目围绕以下内容展开：BT-PVDF陶瓷-聚合物的制备与性能表征；A位和B位离子引入对无铅钙钛矿陶瓷储能表现的影响；顺电体调控Na0.5Bi0.5TiO3相结构与储能性能的关联；协同策略构筑高介电储能性能核壳结构复合陶瓷。利用水热法在200℃下经72h获得高纯纳米BT颗粒，粒径60nm；借助DA对BT颗粒进行表面改性，处理后的BT颗粒分散性明显改善，易与PVDF形成复合薄膜，其介电常数提高至9.37。 探究A位和B位引入离子对BaTiO3基陶瓷储能表现的作用：引入原子配比失衡的Sr0.7Bi0.2TiO3，使Ba2+、Sr2+和Bi3+在A位形成占位竞争，破坏铁电长程有序，促进四方-立方的相转变；B位离子引入可有效增强陶瓷的弛豫性，进而改善储能效率；特别是Li3+掺杂试样其击穿场强提高至340 kV/cm，储能密度2.43 J/cm3。量子顺电体亦可有效抑制铁电长程有序；借助介电和铁电特性，揭示了SrTiO3含量与Na0.5Bi0.5TiO3相演变及储能的关联，确定了与遍历弛豫状态的高温纳米区域和非遍历弛豫状态的低温PNRs相关的两个介电反常，并构建了NBT-xST相图、建立了极化响应和异相极性共存之间的对应关联。发展了协同策略构筑高介电储能性能陶瓷，特别通过电畴调控及应用粘滞聚合物技术成功制得BF-BT核壳结构复合陶瓷，其耐电压高达480kV/cm，能量密度提升至6.15J/cm3，对BF-BT陶瓷的储能应用有重要意义。 ...