An Electrical Contacts Study for Tetrahedrite-Based Thermoelectric Generators

Abstract

High electrical and thermal contact resistances can ruin a thermoelectric device’s performance, and thus, the use of effective diffusion barriers and optimization of joining methods are crucial to implement them. In this work, the use of carbon as a Cu11Mn1Sb4S13 tetrahedrite diffusion barrier, and the effectiveness of different fixation techniques for the preparation of tetrahedrite/copper electrical contacts were investigated. Contacts were prepared using as jointing materials Ni and Ag conductive paints and resins, and a Zn-5wt% Al solder. Manual, cold- and hot-pressing fixation techniques were explored. The contact resistance was measured using a custom-made system based on the three points pulsed-current method. The legs interfaces (Cu/graphite/tetrahedrite) were investigated by optical and scanning electron microscopies, complemented with energy-dispersive X-ray spectroscopy, and X-ray diffraction. No interfacial phases were formed between the graphite and the tetrahedrite or Cu, pointing to graphite as a good diffusion barrier. Ag water-based paint was the best jointing material, but the use of hot pressing without jointing materials proves to be the most reliable technique, presenting the lowest contact resistance values. Computer simulations using the COMSOL software were performed to complement this study, indicating that high contact resistances strongly reduce the power output of thermoelectric devices.

Research on electrical contact performance based on machine vision

“…Typically, component conductivity is judged by contact resistance [3] . The existence of contact resistance results in a local high temperature when current passes through two conductors' electrical contacts; thus, changes in contact resistance directly reflect component conductive performance [4] [5] . Contact resistance variation usually relates to the sum of many small raised areas that form a bump's total area.…”

Temperature-Dependent Sheet and Contact Resistivity Measurements on Ag and Ag-Ni Circuit Pastes

“…Stable high temperature electrical contacts are important for a variety of energy storage, power electronics, and energy conversion devices including solid oxide cells (1)(2)(3)(4)(5), thermoelectric generators (6), solar cells (7), wide-bandgap semiconducting devices (8), and automobile/aerospace components (9). In these applications, electrical contacts with low electronic sheet resistance, low electronic contact resistance, and high adhesion strength are desired.…”