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Anodic protection enables moisture-stable Mg3(Sb, Bi)2 for thermoelectric cooling

Nature Materials (2026)Cite this article

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Abstract

Mg3(Sb, Bi)2 is the most promising candidate as a next-generation thermoelectric cooling material; however, its application is bottlenecked by poor moisture stability. We demonstrate a protection strategy for Mg3(Sb, Bi)2 by constructing anodic phases that are preferentially corroded to protect the cathodic material matrix, as enabled by the in situ formation of uniformly distributed multiscale anodic phases based on a large Pilling–Bedworth ratio, low equilibrium potential, high chemical inertness and rapid oxide/hydroxide coverage ability. Mg17Al12 preferentially corrodes and promotes the formation of a protective film, reducing the average corrosion rate of Mg3(Sb, Bi)2 by 92% to ~95 μm year−1 in air and 86% to ~0.36 μm h−1 in water, achieving excellent corrosion resistance. The cooling performance of the fabricated module is comparable with that of commercial bismuth telluride modules at 300 K, and exceeds them at 325 K and 350 K. Meanwhile, no performance degradation is observed after 28-day aging at 350 K and 70% relative humidity. Our study addresses the issues of moisture stability of Mg3(Sb, Bi)2 during storage, processing and application, and could be extended to other aqueous vapour-sensitive materials.

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Fig. 1: Anodic protection strategy.
Fig. 2: Anodic second phase design method.
Fig. 3: Corrosion resistance performance and mechanism of MBAx materials.
Fig. 4: Interface material design and module performance.

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All data generated or analysed during this study are included in the Article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

J.S. acknowledges the National Key Research and Development Program of China (grant number 2023YFB3809400) and the National Natural Science Foundation of China (grant numbers U23A20556 and 52130106). W.L. acknowledges the Key-Area Research and Development Program of Guangdong Province (grant number 2024B0101040002).

Author information

Author notes

  1. These authors contributed equally: Zhiyuan Yu, Yuxin Sun, Haijun Wu.

Authors and Affiliations

  1. National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin, China

    Zhiyuan Yu, Fengkai Guo, Ming Liu, Hao Wu, Jinsuo Hu, Lankun Wang, Yuke Zhu, Haoyang Tong, Jianbo Zhu, Zihang Liu, Wei Cai & Jiehe Sui

  2. Department of Mechanical Engineering, University of Hong Kong, Hong Kong SAR, China

    Yuxin Sun

  3. State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, China

    Haijun Wu & Xianghong Zhou

  4. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, China

    Jin Hu

  5. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, China

    Weishu Liu

Authors
  1. Zhiyuan Yu
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Contributions

Z.Y., F.G., W.L. and J.S. initiated the concept and established the experimental scheme. Z.Y., F.G. and J.S. proposed the screening strategy for the anodic phase. Z.Y., Y.S., Jinsuo Hu and M.L. synthesized the samples and performed the characterizations. Z.Y. and Jin Hu performed the data analysis of corrosion-related characterizations. Z.Y., Haijun Wu and X.Z. performed the scanning TEM characterizations. Z.Y., L.W. and J.Z. provided theoretical support for the thermodynamic data calculations. Z.Y., Y.S., H.T. and Hao Wu measured the module performance. Z.Y., Y.S., F.G., Jin Hu, M.L., Y.Z., Z.L., W.C., W.L. and J.S. analysed the results. Z.Y., F.G., Y.S., W.L. and J.S. completed the paper.

Corresponding authors

Correspondence to Fengkai Guo, Weishu Liu or Jiehe Sui.

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Nature Materials thanks Lars-Gunnar Johansson and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

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Supplementary information

Supplementary Information (download PDF )

Supplementary Notes 1–7, Figs. 1–39, Tables 1–7 and references.

Peer Review File (download PDF )

Supplementary Video 1 (download MP4 )

In situ-formed protective film of the material exhibits excellent self-healing ability.

Supplementary Video 2 (download MP4 )

Comparison of the corrosion resistance of MB and modifed MBA0.20 samples in water.

Supplementary Video 3 (download MP4 )

Comparison of the corrosion resistance of Fe/MBA0.20/Fe and Mg17 Al12/MBA0.20 /Mg17 Al12 samples in water, highlighting the bulk Mg17Al12 used as an interfacial material for the modified Mg3 (Sb, Bi)2 to further delay corrosion.

Source data

Source Data Fig. 1 (download XLSX )

Maximum temperature difference variation data of the Mg17Al12/MBA0.20T/Mg17Al12 module after aging test at 350 K and constant 70% RH plotted in Fig. 1g.

Source Data Fig. 2 (download XLSX )

Equilibrium potential and P–B ratio data of typical metallic elements plotted in Fig. 2a and ranking data of equilibrium potentials for second phases and hydroxide solubility product of different elements plotted in Fig. 2c.

Source Data Fig. 3 (download XLSX )

Potentiodynamic polarization curves data plotted in Fig. 2a, electrochemical impedance spectroscopy Nyquist data plotted in Fig. 2b, SKPFM analysis data of the MBA0.20 alloy plotted in Fig. 2e, and chemical states of O1s, Mg2p and Al2p at different etching depths plotted in Fig. 2i–k.

Source Data Fig. 4 (download XLSX )

Work-function data of MB, MBA0.20 and Mg17Al12 samples plotted in Fig. 2b, coefficient of thermal expansion data of MB, MBA0.20, Fe and Mg17Al12 phases plotted in Fig. 2c, contact resistivity data of the Mg17Al12/MBA0.20/Mg17Al12 joint plotted in Fig. 2d, relative internal resistance change data with aging time of modules plotted in Fig. 2e, zT value data of MBAx and MBA0.20T samples plotted in Fig. 2f, cooling performance data of modules after 28 days of aging plotted in Fig. 2g and maximum temperature difference data of the Mg17Al12/MBA0.20T/Mg17Al12 module, other Mg-based modules and commercial bismuth telluride modules at different hot-side temperatures plotted in Fig. 2h.

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Yu, Z., Sun, Y., Wu, H. et al. Anodic protection enables moisture-stable Mg3(Sb, Bi)2 for thermoelectric cooling. Nat. Mater. (2026). https://doi.org/10.1038/s41563-026-02563-0

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