Development of Na0.5CoO2 Thick Film Prepared by Screen-Printing Process.

The Na0.5Co0.9Cu0.1O2 thick film with the same thermoelectric performance as a Na0.5CoO2 bulk was formed on an alumina substrate by the screen-printing process. The power factor exceeded 0.3 mW/K2m, with the resistivity of 3.8 mΩcm and the thermopower of 108 μV/K. The thick film without any cracks strongly adhered to the substrate. The high-quality thick film had been realized through the carefully designed and improved process, mixing NaCl to promote the anisotropic sintering of Na0.5Co0.9Cu0.1O2, inserting a CuO interlayer to adhere the film and substrate, and Co-Cu substituting Cu for Co to control the sintering temperature.