中国科学院过程工程研究所机构知识库

作为最丰富的绿色能源之一，人体动能因压电能量收集器（压电纳米发电机，PENG）和可穿戴电子产品的蓬勃发展而备受青睐。多年来，锆钛酸铅（PZT）压电陶瓷一直主导压电电子设备的应用市场，但其高铅含量对人体和环境均造成严重危害。鉴于锆钛酸钡钙（BCZT）的绿色无铅性和与PZT媲美的高压电性，开发环境友好型柔性BCZT压电陶瓷用于人体动能收集，对清洁能源的有效利用和可穿戴电子设备的实际应用具有重要意义。本论文针对PZT压电陶瓷的高铅毒性和传统BCZT无铅压电陶瓷无法用于柔性电子器件等问题，提出了AB位离子共调控思路，平衡了BCZT基无铅压电陶瓷的烧结、相变和电学特性，实现了其陶瓷纤维及薄膜对人体动能的收集，建立了硬性陶瓷与柔性电子设备的应用桥梁。且开发了柔性BCZT基压电-摩擦电复合器件，改善了输出特性和对人体微小动作的灵敏度，展示了其在可穿戴电子设备领域的良好应用前景。本论文取得创新性成果如下：（1）采用Cu2+和Y3+共同调控BCZT结构的AB位，考察了Cu/Y掺杂对BCZT体系烧结、相变以及电学性能的影响规律。探明了体系烧结和相变特性的改善分别归因于氧空位生成加速传质过程和Cu/Y掺杂的容差效应。而Y的施主掺杂效应、加剧的畴壁运动和颗粒间电荷传递则是BCZT-Cu/Y压电陶瓷综合电学性能显著提升的主要原因。进而实现了BCZT基无铅压电陶瓷体系在烧结、相变以及电学特性三方面的共同改善与平衡，明晰了Cu/Y在BCZT固相结构形成过程中的作用机理。（2）为建立硬性陶瓷与柔性电子设备间的应用桥梁，开发了以BCZT-CuY陶瓷粉末为主体的柔性压电复合薄膜，探究了还原氧化石墨烯（rGO）添加对BCZT-CuY颗粒分散性、复合薄膜机械性和电学性能的促进效应。证实了rGO与聚二甲基硅氧烷（PDMS）间的共价键作用既可弥补BCZT-CuY造成的机械损失，又可作为分散和导电介质实现陶瓷颗粒在PDMS中的均匀分布，从而促进复合薄膜综合电学性能的提升。以手指轻敲形式向BCZT-CuY/rGO PENG输入微小人体动能可得到良好输出响应，展示了其在柔性电子器件领域的应用前景。（3）为解决上述薄膜中陶瓷烧结温度过高和含量过低问题，采用静电纺丝技术合成了定向排列的BCZTY压电陶瓷纤维，研究了纤维排列方式和Y掺杂对其物理和电学性质的调控机制。分析得到BCZTY NFs低温烧结活性和高居里温度的内在本质分别归因于烧结中间氧化产物的低反应势垒和纳米纤维的非连续物理特性，阐明了Y施主掺杂效应和电场沿有序纤维排列方向传递促进BCZTY NFs/PDMS复合薄膜综合电学性能的提升机制。相比BCZT-CuY/rGO PENG，BCZTY-NF PENG对手指轻敲驱动人体动能的收集更为有效。（4）为提高上述陶瓷纤维的柔韧性和输出特性，结合高柔性聚偏二氟乙烯-co-六氟丙烯（PVDF-HFP）和高压电性BCZT合成了电纺BCZT/PVDF-HFP复合陶瓷纤维，考察了不同制备方法所得纤维形貌与电学性能之间的构效关系。对比了不同BCZT颗粒在纤维薄膜上的分布状态，得到溶胶凝胶法制备的BCZT纳米颗粒可均匀分散在PVDF-HFP NFs表面（BP-SG NFs），从而显著提高了其复合能量收集器（PTNG）的压电和摩擦电性能。基于BP-SG NFs的粗糙表面和内部间距，无间隙BP-SG PTNG在单双电极模式下均对手部动作表现高灵敏度。（5）为进一步优化BCZT-based PTNG的构造和输出特性，分别以BCZT-CuY/rGO/PDMS和氧化石墨烯（GO）悬浮液作为压电-摩擦电材料和液体电极以合成无间隙GO LS-PTNG，探讨了GO在液体和电输出中扮演的角色。结果表明BCZT-CuY的添加可有效增加PDMS表面粗糙度，同时提高压电和摩擦电效应；GO的添加则可促进液体内部电荷网络形成，有利于电荷传递和改善输出。所得纯GO LS-TENG的最优功率密度高达4.97 W/m2。考察了器件对人体依托皮肤、衣服和金属等驱动动能的收集能力，揭示了其用于可穿戴电子设备的巨大潜能。;As one of the abundant green energy sources, human kinetic energy has attracted considerable attention due to the rapid development of piezoelectric energy harvesters (piezoelectric nanogenerators, PENG) and wearable electronics. Over the decades, PZT has dominated the application market of piezoelectric electronic devices, but its high lead content has caused huge harm to human and the environment. In view of the high piezoelectricity that is comparable to PZT and the lead-free property of BCZT, developing environment-friendly flexible lead-free BCZT piezoelectric ceramic films to harvest human kinetic energy is of great significance for the effective utilization of clean energy and the practical use in wearable electronics.Considering the high lead toxicity of PZT and the unable use of traditional lead-free BCZT piezoceramics in wearable electronics, an AB-site ion co-doping idea is proposed, which balances the sintering, phase transition and electrical properties of BCZT-based lead-free piezoceramics. The fabricated BCZT ceramic fibers or films can effectively harvest human kinetic energy, indicating the established application bridge between rigid ceramics and flexible electronics. Moreover, flexible hybrid devices based on piezoelectric and triboelectric effects (PTNG) are developed, which not only improves the output and sensitivity to human minute motions, but also demonstrates the great potential use in wearable electronics. The innovative results are as follows:(1) Cu2+ and Y3+ were doped to the AB site of BCZT structure, and the impacts of Cu/Y doping on the sintering, phase transition and electrical properties of BCZT system were studied. It is found that the improvement of sintering and phase transition properties is attributed to the formation of oxygen vacancies accelerating mass transfer and the tolerance effect of Cu/Y, respectively. While the significant improvement of electrical properties results from the donor doping effect of Y3+, the intensified domain well motion, as well as the enhanced charge transfer among piezoelectric particles. Therefore, the balance between sintering, phase transition and electrical properties of BCZT-based lead-free piezoceramics is achieved, and a plausible mechanism is obtained to explain the role of Cu/Y in the formation of BCZT solid phase structure.(2) In order to establish the application bridge between rigid ceramics and flexible electronics, piezoelectric composite films based on BCZT-CuY ceramic powders were fabricated, and the promiting effect of rGO on the dispersion of BCZT-CuY and the mechanical and electrical properties of its composite films were explored. It is confirmed that not only can the covalent bond effect between rGO and PDMS compensate for the mechanical loss of the composite film caused by BCZT-CuY addition, but also rGO acts as dispersing and conducting agents to make BCZT particles uniformly distributing in PDMS, and further to enhance the electrical properties of the composite film. With the input of minute human kinetic energy by finger tapping, BCZT-CuY/rGO PENG shows good output, indicating its application prospects in flexible electronics.(3) In term of the high sintering temperature and low content of the above films, uniaxially aligned BCZT ceramic nanofibers were synthesized by electrospinning, and the impacts of fiber alignment and Y doping on the physical and electrical properties were investigated. The low-temperature sintering property and high Curie temperature of BCZTY NFs are ascribed to the low reaction barrier of the intermediate products and the discontinuous physical properties of the nanofibers, respectively. While the donor doping effect of Y element and the electric field along with NFs alignment orientations are two main factors contributing to the enhancement of electrical performance. Compared with BCZT-CuY/rGO PENG, BCZTY-NF PENG can more efficiently harvest human kinetic energy driven by finger tapping.(4) Considering the limited flexibility and output of the above naonfibers, electrospun composite ceramic fibers were developed by combining highly flexible PVDF-HFP and highly piezoelectric BCZT, and the structure-function relationship between different nanofibers obtained by different methods and electrical properties was systemactically studied. It is observed that BCZT nanoparticles prepared by the sol-gel method can be uniformly dispersed on the PVDF-HFP NFs surface, which significantly improves both piezoelectric and triboelectric output of BP-SG PTNG. Owing to the rough surface of BP-SG NFs and the small inter-fiber distance between these NFs, the spacer-free BP-SG PTNG in both single-electrode and two-electrode modes exhibits high sensitivity to hand motions. (5) To further optimize the structure and output of BCZT-based PTNG, spacer-free GO LS-TENG was fabricated using GO dispersion and BCZT-CuY/PDMS as liquid electrode and piezo-triboelectric material, respectively, and the role of GO in the liquid and output was discussed. It is clarified that a proper amount of GO addition can promote the formation of single or several layers of charge channel in the liquid, which benefits the improvements of charge transfer and output performance. Given that the triboelectric output is much higher than the piezoelectric output, the optimal power density of pure GO LS-TENG achieves 4.97 W/m2. This device can effectively harvest human kinetic energy based on skin, clothing and metal, indicating its huge potential applications in wearable electronics.