有机-无机复合气凝胶热电材料的制备与性能研究

Thermoelectric material is an important developing direction of green energy materials. Organic-inorganic composites can comprehensively utilize both the high electric conductivity and Seebeck coefficient of inorganic materials and the low thermal conductivity of organic materials, and they are low in density, cheap in price and easy to process, so it is considered that organic-inorganic composites have potential advantages in using as thermoelectric materials. However, the electric conductivity (σ), the Seebeck coefficient (S) and the thermal conductivity (k) are very difficult to be independently adjusted and controlled to improve the thermoelectric performance of traditional organic - inorganic composites. In order to realize the regulation of σ, S and k individually, phenolic aldehyde /low-dimensional carbon nanoparticle composite aerogels and their carbonized composite aerogels will be prepared in this study. Within the network structure in the composite aerogels, low-dimensional carbon nanoparticles can form percolation routes to improve the electric conductivity. Using the very low density, the nanoporous structure and the multiple interfaces, phonons can be selectively scattered to reduce the thermal conductivity. Multiple interfaces in the composite aerogels can also be used to filter low-energy electron to improve the Seebeck coefficient. Based on the research, we aim at establishing the relationships between micro-structure and thermoelectric properties of the composite aerogels, and lay some theoretical principals and technical supports for the development of new organic-inorganic composite aerogels as thermoelectric materials.

热电材料是绿色能源材料的一个重要发展方向。有机-无机复合材料可以综合利用无机材料的高电导率和Seebeck系数及有机材料的低热导率，且质轻、价廉、易于加工，作为热电材料具有独特的优势。然而，传统的有机-无机复合热电材料往往不能独立地调控电导率（σ）、Seebeck系数（S）和热导率（k），难以提高复合材料的热电性能。为解决这个问题，本研究拟制备酚醛/低维碳纳米粒子复合气凝胶及其碳化复合气凝胶；利用低维碳纳米粒子在复合气凝胶的网络结构中形成逾渗通路，提高电导率；利用复合气凝胶极低的密度、纳米多孔结构和多重界面选择性地散射声子，降低热导率；利用复合气凝胶的多重界面过滤低能电子，提高Seebeck系数；实现S、σ和k的独立调控，建立复合气凝胶微观结构与热电性能的关系，为新型有机-无机复合气凝胶热电材料的研制奠定一定的理论基础和技术支持。

环境问题的日益恶化使人类对绿色能源的需求越来越迫切。热电材料可以直接实现热能与电能之间的转换，具有非常大的应用价值，因而被研究者们大量研究。热电材料转换效率的品质因数由无量纲的热电优值ZT表示，ZT值越大，热电材料的性能越好。除了绝对温度T，ZT值取决于三个相关参数：热导率κ，Seebeck系数α，电导率σ。一个能量转换率高的的热电材料，或者说一个有意义的热电材料的设计思路，必须是对热导率，电导率和Seebeck系数协同调控来完成。为解决这个问题，本研究制备了四种低维碳纳米粒子复合气凝胶及其碳化复合气凝胶；利用低维碳纳米粒子在复合气凝胶的网络结构中形成逾渗通路，提高电导率；利用复合气凝胶极低的密度、纳米多孔结构和多重界面选择性地散射声子，降低热导率；利用复合气凝胶的多重界面过滤低能电子，提高Seebeck系数；实现S、σ和k的独立调控，建立复合气凝胶微观结构与热电性能的关系，为新型有机-无机复合气凝胶热电材料的研制奠定一定的理论基础和技术支持。本项目发表SCI论文6篇，待发表英文论文2篇，EI论文1篇，核心期刊2篇，毕业研究生3名.