Do thermoelectric generator modules degrade due to nickel diffusion

TL;DR

This study demonstrates through calculations that nickel diffusion over 50 years does not degrade thermoelectric generator modules, using composite theory and diffusion models to analyze contact resistance and material properties.

Contribution

It introduces a comprehensive calculation method showing nickel diffusion does not impair thermoelectric modules, considering carrier scattering and phonon interactions.

Findings

Nickel diffusion does not cause degradation over 50 years.

Electrical contact resistance remains stable despite nickel diffusion.

Nickel's role is limited to altering free charge carrier concentration.

Abstract

The paper shows by calculation that the diffusion of nickel even for 50 years does not lead to degradation of thermoelectric generator modules. In the process, we used the theory of composites to calculate the electrical contact resistance, our own diffusion theory of electrical contact resistance, as well as the method for approximating the temperature dependences of thermoelectric material characteristics from the experimental data. When using the above method, it was assumed that the main mechanism of scattering of free charge carriers in a thermoelectric material is their scattering on the deformation potential of acoustic phonons with a free path length independent of energy but inversely proportional to temperature, and the main mechanism of phonon scattering is phonon-phonon scattering with Umklapp, which is not affected by the nickel impurity in the thermoelectric material. Thus, it was believed that the role of nickel is reduced only to a change in the concentration of free charge carriers in the material.