Engineered carbon nanotubes reinforced polymer composites for enhanced thermoelectric performance

Thermoelectric materials have attracted great attention from researchers because of their unique ability to convert thermal energy to electrical energy and vice versa. Based on the coupled theory of transport between heat and electricity in metals, we have carried out finite element simulations on carbon nanotube (CNT)/polyaniline (PANI) composites to compute effective Seebeck coefficients and figures of merit (FOMs). The present study focuses on the effect of interfacial electrical and thermal conductivities, the volume fraction of CNTs and their inclination on the effective electrical and thermal conductivities and thermoelectric performance. It is interesting to report that effective conductivities strongly depend on interfacial conductance in composites where CNTs are transverse to electrical current and heat flow. Interfaces with electrical and thermal conductance less than 10³ S m^-2 and 10⁷ W m^-2 K^-1 respectively isolate CNTs from the matrix. This reduces the effective properties, while the conductivities increase with the CNT content if interfacial conductance is more than these specified values. It was also established that the effective Seebeck coefficient and FOM increase with interfacial electrical conductance, while decreasing with an increase in interfacial thermal conductance. Additionally, the effect of inclination on the electrical and thermal conductivities of composites, the effective Seebeck coefficient and the FOM were analysed. It can be concluded from the study that the Seebeck coefficient and FOM of thermoelectric composites are increased if the CNTs are lying perpendicular to the heat and electrical current flow.