To attain high-performance thermoelectric (TE) devices, making an excellent interfacial connection between TE materials and electrodes is as vital as having high figure-of-merit TE materials. Although CoSb3-based TE devices have recently received significant attention for power generation, the limited long-term service stability is the main obstacle for their applications. As the elementary unit for understanding TE conversion, a TE device is usually made by connecting p- and n-type TE materials with metal-or alloy electrodes in the form of electric in series and heat in parallel. For the TE devices operating in high temperatures, electrode materials typically experience interdiffusion or chemical reaction with TE materials, which can depreciate the performance of TE devices, such as enhancing the interfacial contact resistivity and interfacial thermal resistance and reducing the interfacial mechanical strength. Diffusion barrier layers between TE materials and electrodes are typically used to unravel these interfacial glitches. A decent diffusion barrier material for the TE joints typically encounters the subsequent necessities: matched coefficient of thermal expansion (CTE), low contact electrical and thermal resistivity, alleviated interdiffusion behaviours, higher bonding strength, and outstanding thermal and chemical steadiness. So, metals and alloys are frequently used as diffusion barrier materials and electrodes for the TE joints.

In this work, we have prepared the Ni-Cr-Cu metallizing layer(Ni:Cr: Cu::60:30:10 wt%) indigenously as the diffusion barrier layer of CoSb3-based TE joints by the spark plasma sintering method and have systematically investigated their interfacial behaviours during the ageing process. The processed Ni-Cr-Cu /skutterudite joint interface is continuous without having any crack and has low contact resistance (< 12 μΩ·cm2). The contact resistance at the interface of the joints decreases to 7 μΩ·cm2 under thermal ageing at 823 K for 15 days in vacuum. The mechanical properties of the joints are not degraded even after ageing at 823 K for 15 days. The average lifetime of the skutterudite device using the Ni-Cr-Cu/ Dy0.4Co3.2 Ni0.8Sb12 joints is calculated to be 11 years while maintaining the hot side temperature of the device at 773 K. Our results demonstrate that indigeneously prepared Ni-Cr-Cu/Co4Sb12 thermoelectric joints can be effectively used for skutterudite module fabrication.