Copper-Nickel and copper-cobalt thermoelectric generators: power-generating optimization through structural geometrics

Abstract

In this paper of thermoelectric generators, metals are used as the prospective thermoelectric materials or thermoelements on flexible copper (Cu)-clad polyimide substrate. The fabricated thick film generators have planar and lateral structures with lateral heat flow and lateral thermopile layout. Hereby, two prototypes of thermoelectric generators are made, the first employing Cu and nickel (Ni) and the second Cu and cobalt (Co) as their positive and negative thermoelements, respectively. This paper also investigates the roles of geometrical structures such as the thermoleg's length and width and the generator's size in promoting elevated thermoelectric power generation. Consequently, the highest performing thermoleg designs (length: 5-20 mm; width: 100- 1000 μm) for the two prototypes are identified as having a length, width, and thickness of 5 mm, 1000 μm, and 31μm, respectively, with generator dimensions of 1.1 cm length and 4.3 cm width. Collectively, this design has an accumulated average temperature difference, output power density, and thermoelectric efficiency factor of 60 K, 0.59μ Wcm-2, and 1.64×10 4 μ Wcm-2K-2, respectively, for the Cu-Ni generator, while the corresponding values for the Cu-Co generator are 64 K, 1.15 μ Wcm-2, and 2.81 × 10 4 μ Wcm-2K-2. An improvement factor of 1.71 is realized by the Cu-Co generator compared to the Cu-Ni one due to its larger Seebeck coefficient and figure of merit. This highlights the Cu-Co metallic couple as an encouraging thermoelement in thermoelectricity. Promisingly, the thick film and lateral device structures are more compatible and favorable for metal-based thermoelectric generators.