Thermoelectric properties in multifaceted Bi/lithium cobaltate composites

Abstract

Thermoelectricity is one of the most appealing way to convert waste heat into electrical energy. Lithium cobaltate was synthesized without water and surfactants (WOWS) by sol–gel method. Composites of phase pure lithium cobaltate were prepared with different weight percent (5%, 10%, 15%) of bismuth. Structural analysis was done by using X-ray diffraction (XRD) technique. XRD of all samples confirmed the rhombohedral structure. Crystallite size of as-prepared sample was found in the range of 10–27 nm and that of sintered composites was found in the range of 29–47 nm. DC electrical properties as a function of temperature was measured by using four-probe method, in the temperature range of 300–413 K. Thermal transport properties of all samples were done by using advantageous transient plane source method. Thermal conductivity, thermal diffusivity, and volumetric heat capacity were measured as a function of temperature in the temperature range of 300–413 K. As expected, it was observed that thermal conductivity of composites with 15% Bi i.e., 1.0866 W/m K at 413 K was very much less than that of lithium cobaltate. Seebeck coefficient was measured as a function of temperature and these were also in line with the electrical and thermal transport data. Variation in Seebeck coefficient is observed both with respect to temperature and the maximum value is obtained with 5% bismuth i.e., 703.89 μV/K.