Preparation and thermoelectric properties of TE module by a spark plasma sintering method

NaCo2O4 and 0.5at%-Sb doped Mg2Si have excellent thermoelectric properties. We tried to fabricate a thermoelectric module composed of these materials and using Ni plates as electrodes. The fine powder of NaCo2O4 was prepared by metal-citric acid complex decomposition. 0.5at%-Sb doped Mg2Si bulk was ground to powder and sieved to a powder particle size of 75 micrometers or less. These powders were sintered using spark plasma sintering (SPS) to obtain a body of NaCo2O4 and 0.5at%-Sb doped Mg2Si. These thermoelectric materials were connected to the Ni plates by using the SPS method. The whole process took a very short time (less than 2 min) and could be done at low temperature (below 873 K). The open-circuit voltage values were 82.7 mV, and the maxima, maximum output current and maximum output power, for the single module were 212.4 mA and 6.65 mW at Delta T = 470 K.