<p>The bonding strength at the interface between the barrier layer and the thermoelectric material is a critical factor that influences the service life and reliability of a thermoelectric device. Bi₂Te₃-based thermoelectric devices predominantly use nickel (Ni) as a barrier layer. However, the interface between the Ni barrier layer and the Bi₂Te₃ thermoelectric material represents the most vulnerable part of the device. In this study, different forms of Ni barrier layers were investigated, including Ni powder, Ni foil, and porous Ni. The micro-morphology of Ni barrier layers in different states and the blocking effect of Ni on Bi₂Te₃ were investigated. This work also investigated the shear strength of the bonding interfaces between different Ni barrier layers and Bi₂Te₃. The results show that porous Ni with rough microscopic surfaces, a continuous structure, and abundant surface area can form a tight mechanical bonding with Bi₂Te₃ without cracking. The Ni barrier layer effectively blocks Bi, Te, and Sb elements, forming an approximately 10&#xa0;µm metallisation layer at the bonding interface. This results in a good metallurgical bonding between Ni and Bi₂Te₃. The shear strength between the porous Ni and Bi₂Te_2.7Se_0.3 reached 17.33&#xa0;MPa, which was 57.5% higher compared to Ni foil. In addition, the barrier layer prepared by porous Ni effectively delayed the destruction of the interface, enhancing the overall reliability of devices.</p>