低成本高导电的高温热电应用石墨气凝胶研究

To meet the dual requirements of efficient thermal insulation and thermoelectric conversion under high-temperature conditions in industrial and aerospace applications,this study fabricates a graphite aerogel with a highly oriented lamellar structure using flake graphite as the primary matrix and hydroxyethyl cellulose (HEC)/white cement as the 3D skeleton template, through the directional freeze-drying method and high-temperature carbonization technique.The aerogel demonstrates a wide operational temperature range from room temperature to 700 ℃, achieving an ultrahigh electrical conductivity of 6 7.6 3 S · cm^-1 at 700 ℃.Its cost-normalized electrical conductivity exceeds that of existing conductive aerogels by 2-3 orders of magnitude, offering significant cost advantages.Additionally,a two-stage Voronoi diagram conductivity model is proposed for the lamellar fractal structure. Based on this mode, the microscopic mechanism by which HEC enhances conductivity in low-mesh graphite while suppressing conductivity in high-mesh graphite is revealed.The graphite aerogel’s excellent thermal stability at high temperatures,combined with a stable Seebeck coefficient (1 2—1 7 μV·K^-1)and effective suppression of intrinsic graphite thermal conductivity (reduced by 3 orders of magnitude ), highlights its potential for high-temperature thermoelectric applications.Through experimental validation and theoretical modeling, this study provides a theoretical foundation and design guidance for the practical application of thermoelectric aerogels.