Characterization and analysis of electrothermal, thermoelectric, and current discharge properties of alkali-activated materials: Implications for energy conversion

Abstract

Alkali-activated mortar (AAM) show promising potential for net-zero energy buildings due to their excellent electrical conductivity. This study investigates the multifunctional properties of AAM for energy conversion applications, examining the influence of conductive fillers and additives on AAM's mechanical and electrical properties, the effects of curing age, moisture content, temperature, and applied load on AAM's resistivity, and exploring its electrothermal, thermoelectric, and current discharge properties. Key findings reveal that conductive fillers and additives enhance AAM's conductivity but decrease the mechanical properties, while an equivalent circuit diagram accurately describes AAM's electrochemical impedance spectroscopy. AAM's resistivity increases with curing age and moisture loss but decreases with rising temperature and applied load. The material demonstrates stable and efficient electrical-to-thermal energy conversion across various voltages, with plain AAM exhibiting a superior Seebeck coefficient of 1353 μV/°C, outperforming OPC-based systems in thermoelectric properties. Notably, an Al-AAM-Cu battery maintains a current density above 2 mA/m² for 79 h, meeting ISO standards for impressed current cathodic protection of steel reinforcement in concrete structures. These results highlight AAM's potential as a multifunctional material for energy harvesting, storage, and corrosion protection in sustainable construction applications, paving the way for innovative solutions in energy-efficient building design.