Elemental Diffusion and Service Performance of Bi2Te3-Based Thermoelectric Generation Modules with Flexible Connection Electrodes

In this work, the elemental diffusion and service performance of Bi2Te3-based thermoelectric generation (TEG) modules with flexible Al electrodes were evaluated at a temperature difference of 240°C and a cold junction temperature of 50°C. The results indicated that while the maximum output power (P max) and open circuit voltage (U 0) first increased rapidly and then decreased gradually with service time, the dynamic inner-resistance (R i) showed the opposite trend. Obvious defects and elemental diffusion across the interfaces were observed and resulted in the performance degradation of the TEG modules. The Ni barrier layer with a thickness of 8–10 μm could not effectively restrain the elemental diffusion for the TEG applications at the high operating temperatures. Al was not suitable as the electrode material for the Bi2Te3-based TEG modules due to its ready absorption of Se from the n-type thermoelectric legs. Encouragingly, we found that the Al electrode could restrain the diffusion of the other elements such as Bi, Te, Sb, Cu, Ni, and I. These results provided insight into the improvement of the service performance of the TEG modules.