基于三维互联压电气凝胶的柔性能量收集器制造技术研究

Mechanical flexibility and piezoelectricity are both required for an energy harvester which is compatible and stable for complex mechanical energy and collects energy efficiently. The currently available ceramic-polymer composites with piezoelectric ceramic nanostructures dispersed in polymer matrix present excellent flexibility. However, the large stiffness disparity of the material constituents and the spatial discontinuity of the ceramic phase in these composites render fairly poor load transfer from the surrounding polymer matrix to the active ceramic fillers, and thus significantly limiting energy transfer efficiency. Herein we introduce a new class of high-performance flexible energy harvesters based on three-dimensional (3-D) interconnected nanosacle piezoelectric aerogels. M13 bacteriophage (phage) was genetically engineered for the use as a template to establish a fabrication process of 3-D interconnected nanoscale piezoelectric aerogels in by the property of the genetically modified M13 which displays specific affinity for PZT ions. The problem of low efficiency of load transfer is solved by the proposed ceramic-polymer composite. The main research contents include the study of the response mechanism between the mechanics and piezoelectricity for the flexible ceramic-polymer composites, the mechanism of load-transfer between the polymer matrix and the piezoelectric material, the optimization design of structure of polymer matrix and 3-D interconnected piezoelectric aerogels. It is expected to realize the excellent combination of flexibility and piezoelectric and improve the conversion efficiency of mechanical energy into electrical energy.

实现对形式多样的机械能进行高效转换，除了需要压电材料具有高的压电性能外，还需具有良好的柔性。现有的压电陶瓷/聚合物复合材料虽具有良好的柔性，但是由于材料成分间机械模量的巨大差异和压电分散相的空间不连续性，存在从聚合物基体向陶瓷填料的应力传递效率低的问题，严重限制了能量转换效率。因此，本项目提出一种基于三维互联纳米压电气凝胶的柔性能量收集器制造技术。通过基因改造M13噬菌体构建微生物模板，利用噬菌体特异吸附PZT压电材料，形成具有纳米特征尺度的压电气凝胶。以此为骨架填充聚合物制备的压电复合材料，有效解决应力传递效率低的问题。重点探索柔性压电复合材料的机械-压电响应机理、两相间的机械载荷传递机制和压电气凝胶成型矿化机理，优化三维互联压电结构和柔性基质的结构设计，实现高柔性与高压电性能的有效结合、机械能到电能的高效转换。

实现对形式多样的机械能进行高效转换，除了需要压电材料具有高的压电性能外，还需具有良好的柔性。现有的压电陶瓷/聚合物复合材料虽具有良好的柔性，但是由于材料成分间机械模量的巨大差异和压电分散相的空间不连续性，存在从聚合物基体向陶瓷填料的应力传递效率低的问题，严重限制了能量转换效率。模板法自组装是近些年来兴起的制备纳米材料的一种自下而上的方法，具有生物兼容性好、易于批量化等优势，相比于传统的纳米材料的合成方案而言，机理尚不成熟，工艺实现难度较高。本研究采用模板自组装法并以M13噬菌体作为模板制备纳米线基的压电复合薄膜，以复合薄膜为敏感元件制备了柔性压电换能器。此外，扩展研究了亲水-超疏水温敏材料、纳米银以及多层级吸声材料的制备。.以M13噬菌体作为骨架模板，结合溶胶-凝胶制备纳米材料的原理，制备了钛酸钡压电纳米线的凝胶，并通过退火工艺实现了其混合物的无机矿化过程，最终获得直径在30-50nm长约1μm的纳米线网络。基于纳米线制备工艺的基础上对纳米线形貌可控进行了研究。通过压电力显微镜的测试测得了蝴蝶曲线，证明了其具有良好的微观的压电性。通过计算可以得出其微观的压电应变常数约为1.39nm/V，相较之于此前的压电纳米线的制备研究而言，压电性能有较大的提升。通过旋涂-固化的工艺实现了PDMS柔性基体与无机纳米线良好分散，进行了表面形貌的表征。制备了三明治结构的压电换能器，对其开路电压和短路电流进行了定量的测试，开路电压在毫伏级别，短路电流在微安级别，这相较之于之前的同类型器件有很大的提升。成功构建了超亲水-超疏水可变材料表面并合成了粒径在10-20nm范围的纳米银。所制备的多层级吸声结构展现出优异的声学性能。

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