高效柔性摩擦纳米发电机的结构设计与性能优化

Triboelectric nanogenerators (TENG) are able to harvest energy from various mechanical motions, such as human walking, ocean waves and air flows, and transform it into electricity. They can either serve as an excellent self-powered mechanically triggered sensor or, as an energy provider module, which are primary components for “Internet of Things (IoT)”. Featured with high output performance, low cost, and maintenance-free, TENG offers a better power solution for IoT, which can accelerate the third wave of information and big data industry and help us achieve world’s preeminent position. As a fundamental research, TENG also favors many applications including wearable electronics and blue energy harvesting that converting energy from ocean waves into electricity. Among its performance metrics, output power density is of the first priority, which is quadratically determined by surface triboelectric charge density. To improve it, main limitations from contact efficiency and air breakdown are to be overcome. .Here in this project, on one hand, the specific triboelectric surface area and contact efficiency can be enhanced based on contact structure optimization via soft, fragmental and three-dimensional contacting techniques to boost the output power density. On the other hand, ultra-thin dielectric layer can be created to reduce the limitation from air breakdown upon tribo-charge density, which will leverage energy harvesting efficiency as the ratio of subsistent tribo-charge after contacting is uplifted. Based on the increased amount of transferred charge, the mechanism of triboelectrification and the kinetics process of charge transfer will be further studied, and also, the integrated device structures will be refined for the actual application scenarios to build advanced TENG with high volume power density. This work not only can enrich the theory family of triboelectrification as well as bring in new evidences for the on-going debate among the existing hypothesizes, but also provide methodology for the design and implement of advanced TENG so as to accelerate the development of self-power system, IoT and blue energy.

摩擦纳米发电机能够将人体运动、机械振动和海洋波浪等机械能转化为电能，可广泛地运用于可穿戴电子器件和物联网作为自驱动电源模块，为加速以物联网为核心的大数据时代和第三次信息产业浪潮的实现奠定坚实的基础，并能高效获取海洋波浪能作为蓝色能源以缓解能源危机和环境问题。作为能量器件，最核心的性能指标是输出功率密度，其与表面摩擦电荷密度呈平方关系。本项目拟从柔性接触和碎片化结构显著提高摩擦接触有效性出发，设计超薄介质层推高空气击穿对表面电荷密度的制约天花板，进一步通过界面设计实现三维接触提高摩擦比表面积，在摩擦电荷密度大幅提升的基础上，研究摩擦起电的动力学过程，最后针对应用场景优化器件结构，以期获得具有高体积功率密度的摩擦纳米发电机。本项目的研究不仅可以充实摩擦起电的理论体系，而且能够指导高性能摩擦纳米发电机的设计与实现，推动自驱动系统以及物联网和蓝色能源的快速发展。

随着物联网技术的快速发展，其海量分布式传感器的能源供应是急需解决的问题。作为新一代分布式能源供给器件的重要组成部分，摩擦纳米发电机（TENG）可以将环境中的机械能转化为电能，是解决物联网传感器电力供应的有效方案。为了探究摩擦纳米发电机的表面电荷密度极限，突破表面电荷密度对摩擦纳米发电机性能的制约，本项目首先从理论角度出发，建立了摩擦纳米发电机表面电荷密度与介质层厚度的物理模型，阐明了表面电荷密度的关键影响因素，并且解释了TENG中寄生电容对其性能的影响机制，从理论上为高性能TENG的设计提供了指导；另一方面，在项目支持下，我们首次提出了基于静电击穿的直流TENG器件，并通过微观结构和材料设计获得了8.8 mC m-2的高摩擦电荷密度，打破了现有的摩擦纳米发电机电荷密度最高值，并以此为基础提出了直流TENG的材料选择模型，为高性能直流TENG的材料设计提供依据，减少实验设计的试错时间，为直流TENG的实际应用提供指导；同时，通过在传统固-固摩擦界面添加润滑介质构建合理的界面接触情况，抑制了界面击穿，降低界面击穿造成的电荷衰减，成功将摩擦纳米发电机的功率密度提高到3.45 W m-2 Hz-1，是现阶段摩擦纳米发电机的三倍多，并使TENG的工作寿命可以提升到50万循环以上，解决了滑动模式TENG的连续工作寿命短这一关键问题，使滑动模式的摩擦纳米发电机在实现应用的路上迈出了坚实的一步；最后从柔性接触和碎片化结构显著提高摩擦接触有效性出发，设计了一体化自充电能源系统，实现了周围环境中收集能量、存储能量、直接驱动电子器件的多功能系统，为TENG在微纳能源与自驱动传感的实际应用奠定了基础。