Discovery of ZrCoBi based half Heuslers with high thermoelectric conversion efficiency

TLDR

Thermoelectric materials convert waste heat to electricity, with the dimensionless figure‑of‑merit (ZT) being the key performance metric; however, half‑Heusler compounds, though promising for power generation, typically exhibit lower ZTs than other material systems. We discovered p‑type ZrCoBi half‑Heuslers with a record‑high ZT of ~1.42 at 973 K and ~9 % conversion efficiency over ~500 K, attributed to a high band degeneracy of 10 and low thermal conductivity from a low mean sound velocity, making them promising for high‑temperature power generation.

Abstract

Abstract Thermoelectric materials are capable of converting waste heat into electricity. The dimensionless figure-of-merit (ZT), as the critical measure for the material’s thermoelectric performance, plays a decisive role in the energy conversion efficiency. Half-Heusler materials, as one of the most promising candidates for thermoelectric power generation, have relatively low ZTs compared to other material systems. Here we report the discovery of p -type ZrCoBi-based half-Heuslers with a record-high ZT of ∼1.42 at 973 K and a high thermoelectric conversion efficiency of ∼9% at the temperature difference of ∼500 K. Such an outstanding thermoelectric performance originates from its unique band structure offering a high band degeneracy ( N v ) of 10 in conjunction with a low thermal conductivity benefiting from the low mean sound velocity ( v m ∼2800 m s −1 ). Our work demonstrates that ZrCoBi-based half-Heuslers are promising candidates for high-temperature thermoelectric power generation.