Atypically Solidifying Metals Enable State‐of‐the‐Art Bismuth Telluride‐Based Thermoelectrics

ABSTRACT Engineered nanoprecipitates and dislocation networks are highly effective in suppressing lattice thermal conductivity, especially for thermoelectric materials with intrinsically short phonon mean free path. However, their concurrent integration remains largely elusive. Herein, we propose an atypically solidifying metal strategy to simultaneously engineer abundant nanoprecipitates and dislocation networks in Bi 0.35 Sb 1.65 Te 3 . Specifically, Ga is selected owing to its limited solubility, which facilitates the formation of uniformly dispersed nanoprecipitates. Upon solidification, these nanoprecipitates undergo anomalous volumetric expansion against the thermal contraction of the surrounding matrix, generating substantial internal stress that triggers the formation of extensive dislocation networks. Notably, these nanoprecipitates also exhibit an anomalously elevated melting point relative to bulk Ga, reinforcing microstructural robustness. Together with the resulting Ga‐Bi 0.35 Sb 1.65 Te 3 heterointerfaces further intensifies phonon scattering and enables carrier energy filtering, simultaneously suppressing lattice thermal conductivity and improving the power factor. Consequently, a state‐of‐the‐art zT of 1.53 at 375 K is achieved in p‐type Bi 0.35 Sb 1.63 Ga 0.02 Te 3 , delivering a power generation efficiency of 7.0% under a temperature gradient of 230 K, along with a maximum cooling temperature difference of 69.0 K at a hot‐side temperature of 303 K. These results establish atypically solidifying metals as a powerful and generalizable microstructure design paradigm for high‐performance thermoelectric materials.