Through-thickness thermoelectric power of a carbon fiber/epoxy composite and decoupled contributions from a lamina and an interlaminar interface

Abstract

Thermoelectric structural materials are potentially attractive for large-scale energy harvesting. Through filler incorporation and unprecedented decoupling of the bulk (laminae) and interfacial (interlaminar interfaces) contributions to the Seebeck voltage (through-thickness Seebeck voltage of a crossply continuous carbon fiber/epoxy composite laminate), this work provides thermoelectric power magnitudes at ∼70°C up to 110, 1670 and 11,000μV/K for the laminate, a lamina and an interlaminar interface, respectively. The interface provides an apparent thermoelectric effect due to carrier backflow. The interfacial voltage is opposite in sign from the laminate and lamina voltages and is slightly lower in magnitude than the lamina voltage. An interlaminar filler, particularly a thermoelectric filler (tellurium or bismuth telluride), enhances the magnitudes of the voltages and thermoelectric powers of the laminate, lamina and interlaminar interface. Bismuth telluride results in negative values of the voltages and thermoelectric powers of the laminate and lamina; tellurium results in positive values. Tellurium content increase or tellurium particle size decrease enhances the magnitudes of the voltages and thermoelectric powers of the laminate, lamina and interlaminar interface. Decreasing the curing pressure decreases these magnitudes, due to fiber–fiber contact decrease. The resistance-related voltage at each electrical contact is unprecedentedly decoupled from the thermoelectric specimen voltages.