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.