木质纤维素网络离子热电凝胶的制备与性能

Preparation and properties of lignocellulose network ionic thermoelectric gels

  • 摘要: 热电材料可实现热能直接转换为电能,在生活和工业废热再利用方面得到越来越多的应用。然而,传统的无机热电材料存在热功率(或Seebeck系数)低和导热率高的问题,在低品位废热(<130℃)收集方面不具备优势。利用离子热扩散效应(Soret效应),以纤维素作为网络、聚乙烯醇(PVA)为电解质基质,用简单的注射器注射法制备了纤维素网络离子热电凝胶,并研究了不同含量的NaOH、LiOH作为离子供体的热电性能差异。采用FTIR光谱对材料内部基团进行表征,同时自制的热电测试装置证明了其较高的热功率。研究结果表明木质纤维素网络的加入使离子电导率达到3.31 mS·cm−1,相比纯PVA离子凝胶提升了98.2%。同时,纤维素的加入降低了热导率,使其在人体体温和26℃室温的温差中保持上下面温差恒定较长时间。在2℃温差下离子Seebeck系数达到+12 mV·K−1。该研究提出了一种具有成本效益且环保的低品位废热再利用方案,对人类社会的可持续发展具有较大意义。

     

    Abstract: Thermoelectric materials enable the direct conversion of thermal energy into electrical energy and are increasingly used in domestic and industrial waste heat reuse. However, traditional inorganic thermoelectric materials suffer from low thermal power (or Seebeck coefficient) and high thermal conductivity, and do not offer advantages in low-grade waste heat (<130℃) collection. Using the ionic thermal diffusion effect (Soret effect), cellulose network ionic thermoelectric gels were prepared by a simple syringe injection method using cellulose as the network and poly(vinyl alcohol) (PVA) as the electrolyte matrix, and the differences in the thermoelectric properties of different contents of NaOH and LiOH as the ion donor were investigated. FTIR was used to characterize the internal groups of the material, while a homemade thermoelectric test setup proved its higher thermopower. The results showed that the incorporation of cellulose results in an ionic conductivity of 3.31 mS·cm−1, which is enhanced by 98.2% compared to the pure PVA ionogel. At the same time, the addition of cellulose reduces the thermal conductivity to keep the upper and lower temperature difference constant for a longer period of time under the temperature difference between human body temperature and 26℃ room temperature. The ionic Seebeck coefficient reaches +12 mV·K−1 at 2℃ temperature difference. This research proposes a cost-effective and environmentally friendly solution for the reuse of low-grade waste heat, which is of greater significance for the sustainable development of human society.

     

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