Abstract: The long-term operational stability of thermoelectric devices in extreme environments places stringent demands on their interconnection structures. In this work, a clamped thermoelectric device based on a segmented Bi₂Te₃–PbTe architecture is developed. A flexible electrode composed of graphite and copper foil is introduced at the hot side to form an elastic, self-adaptive contact interface, effectively relieving interfacial thermal stress and reducing contact resistance. At the cold side, a corrugated ohmic ring and spring-loaded insulating sleeve are employed to decouple the motion of P- type and N-type thermoelectric legs, thereby enhancing the device’s thermomechanical stability. The fabricated device delivers an output power of 14 W, a conversion efficiency of 10%, and a power-to-mass ratio of 9.33 W/kg under a temperature difference of 450 K, significantly outperforming conventional clamped designs. Moreover, after 250 thermal cycles between 300 K and 723 K, the device exhibits no noticeable degradation, demonstrating excellent operational reliability.