Abstract
Thermoelectric materials offer an exceptional opportunity to convert waste heat into electricity directly, yet their widespread application remains hindered by intrinsic brittleness and poor processability. Here, we introduce a graded ball milling strategy that fundamentally enhances the mechanical robustness and processability of YbZn(2)Sb(2)-based thermoelectrics. By refining grain microstructure, increasing dislocation density, and promoting intermediate-angle grain boundaries, this approach enables the fabrication of crack-free, large-size, disc-shaped, and microscale dices while maintaining excellent thermoelectric performance. Extending this strategy to a broader class of brittle Zintl compounds, including AZn(2)Sb(2), AMg(2)Sb(2), and ACd(2)Sb(2) (A = Yb, Mg, Ca, Sr, Ba), we achieve a pre-formation cohesive energy of 9.1 eV atom(-)(1) and relatively low lattice thermal conductivity of 0.5 W m(-1) K(-1) in Yb(0.5)Mg(1.3)Zn(1.2)Sb(2). Integrated with n-type Mg(3.1)Nb(0.1)Sb(1.5)Bi(0.49)Te(0.01), the thermoelectric module achieves a conversion efficiency exceeding 10% under a 458 K temperature gradient, operating for more than 40 hours steadily. This work establishes a scalable and versatile strategy for reconciling mechanical durability with high thermoelectric performance, paving the way for next-generation thermoelectric devices with enhanced reliability and industrial viability.