Emerging thermoelectric cementitious nanocomposites: Mechanisms, design and performance

Thermoelectric cementitious composites (TECCs) function as intelligent construction materials with structural load-bearing capacity and energy harvesting capability. They offer strong potential for future smart and sustainable buildings and infrastructure. Despite the rapid progress, most of the literature emphasizes the improvement of thermoelectric performance by fillers, while ignoring the discussion of load-bearing capacity and practical applications. This study reviews the latest research progress, including conductive network dispersion, nanoscale filler design, thermoelectric performance enhancement, mechanical property optimisation, environmental influence and practical application. Carbon-based materials primarily enhance thermoelectric properties through their excellent electrical conductivity, while metal oxides contribute by improving the Seebeck coefficient and thermal conductivity. It remains a major challenge to simultaneously improve the electrical conductivity and Seebeck coefficient of TECCs by integrating carbon-based materials and metal oxide materials to achieve a significant breakthrough in the thermoelectric performance. Currently, TECCs suffer from low energy conversion efficiency, with the dimensionless figure of merit (ZT) typically below 10⁻². Modulating phonon and electron transport via interface engineering has become an emerging strategy for improving thermoelectric performance. Regarding mechanical properties, an appropriate content of conductive filler can improve the compressive strength and flexural strength of TECCs. Furthermore, the extreme service environment temperatures (253 K and 343 K) of TECCs cause varying degrees of degradation of their mechanical properties and chloride ion resistance. In addition, factors such as the matrix type, fabrication method, moisture and temperature can significantly affect ion migration and thermoelectric performance. Future research should focus on the synergistic transport of ions and electrons to optimize thermoelectric performance. Finally, this study systematically summarizes the current application of TECCs and provides guidance for the large-scale application of TECCs. The large-scale design of TECCs is an important way to increase power density and improve the quality of output electrical energy. These findings will provide a foundation for TECC applications and insights into improving their thermoelectric performance in smart structures.