基于纤维素纳米晶体的压电型机械能收集装置

Piezoelectric energy harvester is regarded as the key technology to realize self-powered devices as it can convert ambient mechanical vibration into electricity. It is noticeable that the synthetic process of artificially piezoelectric materials, however, is energy consuming and causes pollution issues, which runs counter to the concept of sustainability. To solve the problem, this project seeks to use naturally piezoelectric biopolymer, cellulose, as the alternative candidate for the conventional piezoelectric materials, to fabricate a more economical and environment friendly energy harvester. First, cellulose nanocrystal will be blended with antibacterial ZnO nanofillers to obtain piezoelectric nanocomposites with good biostability, and the factors that influence the piezoelectricity will be elucidated. Then novel liquid metal based electrodes will be used to replace the conventionally solid metal electrodes, and the 100% connectivity between the electrodes and the piezoelectric materials is expected to improve the efficiency of electric energy collection. Finally the structure property relationships that affect the energy conversion rate will be studied, and based on this a high-efficiency piezoelectric energy harvester can be obtained via structural optimization. This project aims to realize the specific function of biopolymers, accelerating the process to achieve biocompatible and environment friendly electronic materials.

压电型机械能收集装置可将日常生活中的振动转换为电能，因而被认为是实现自供能电子设备的关键。但需要指出的是，人工压电材料在合成过程中会耗费大量的能源并产生环境污染，与可持续发展的观念背道而驰。为解决该问题，本项目拟采用具有天然压电性的生物高分子纤维素取代传统压电材料，以期获得更加经济、环保的机械能收集装置。首先，将纤维素纳米晶体与具有抗菌性的ZnO纳米填料共混，制得具有良好压电性且不易变质的纳米复合材料，影响材料压电性的因素也将会被确定。而后使用新型液态金属电极取代传统固态金属电极，该电极可与压电材料100%的结合得以有效提高电能的采集率。最后通过结构优化，确立结构属性关系，获得具有高能量转换率的压电型机械能收集装置。该课题旨在实现天然高分子的特定功能化，为推动制备生物、环境友好的电子材料奠定基础。

以压电型纳米发电机（PENG）为代表的机械能收集装置是应对能源危机，提供新型可再生能源的重要途径，但传统压电陶瓷或压电高分子在制备过程中耗能高且会造成污染，与可持续发展的理念背道而驰。本课题旨在利用自然界中广泛存在的纤维素为研究对象，探索提高其压电性能，进而取代传统压电材料，用于新一代绿色、经济、环保的机械能收集装置的可行性。研究中采用了新型二维纳米材料MXene为填料，与纤维素纳米晶体（CNF）复合制备具有良好力学及电学特性的气凝胶材料构筑PENG，并对相关器件的性能进行优化。得益于MXene的特殊性质，复合气凝胶中的CNF的微观结构得以优化，且在局部产生诱导极化效应，这种简单易行的协同优化策略显著提升了纤维素的压电性能，避免了传统压电材料制备中高能耗的电极化流程，具有重要的经济及环保意义。制得的PENG经优化后可有效收集人体运动产生的低频机械能，解决了传统PENG在低频模式下输出效率底下的问题，有助于可穿戴电子材料及自供能设备的开发。