Device level assessment of Ni and Ni45Cu55 as electrodes in Mg2(Si,Sn)-based thermoelectric generators

[Display omitted] •Vision: Waste heat recovery using Mg2(Si,Sn)-based thermoelectric generators.•Challenges: Degradation in n- Mg2(Si,Sn) due to Mg loss and contact-electrode-interdiffusion.•Design Solution: Binary n-Mg2Si as stable n-type leg in thermoelectric generators with Ni45Cu55 as electrode.•Achievement: TEG prototype with Pmax ∼0.79 W/cm2 at a temperature difference of ∼375 K.•Key finding: Improved performance due to the suppression of loss mechanisms. Owing to efficient thermoelectric conversion, non-toxicity, low density and cost, Mg2(Si,Sn)-based solid solutions hold potential for mid-to-high temperature waste heat recovery. Yet, challenges arise from n-Mg2(Si,Sn) degradation at ≥400 °C caused by Mg loss and charge carrier reduction, particularly in Sn-rich compositions. To build a thermoelectric generator (TEG) stable up to 400 °C, we propose binary Mg2Si as the n-type leg. Using Ni45Cu55and Ni yields low electrical contact resistance (