中国物理B ›› 2025, Vol. 34 ›› Issue (9): 97306-097306.doi: 10.1088/1674-1056/add4fa

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Preparation of high-performance Cu2Se thermoelectric materials by the KCl flux method and research on thermoelectric transport performance

Yonggui Tao(陶永贵)1, Chisheng Deng(邓池升)1, Jicheng Li(李吉成)1,2, Wen Ge(葛文)1, Ying Zhang(张盈)1, Yujie Xiang(向玉婕)1, and Shukang Deng(邓书康)1,†   

  1. 1 School of Energy and Environmental Science, Yunnan Normal University, Kunming 650500, China;
    2 School of Intelligent Science and Engineering, Yunnan Technology and Business University, Kunming 650201, China
  • 收稿日期:2025-02-25 修回日期:2025-04-30 接受日期:2025-05-07 出版日期:2025-08-21 发布日期:2025-09-04
  • 通讯作者: Shukang Deng E-mail:skdeng@126.com
  • 基金资助:
    thermoelectric effects|low thermal conductivity|liquid-like|flux method

Preparation of high-performance Cu2Se thermoelectric materials by the KCl flux method and research on thermoelectric transport performance

Yonggui Tao(陶永贵)1, Chisheng Deng(邓池升)1, Jicheng Li(李吉成)1,2, Wen Ge(葛文)1, Ying Zhang(张盈)1, Yujie Xiang(向玉婕)1, and Shukang Deng(邓书康)1,†   

  1. 1 School of Energy and Environmental Science, Yunnan Normal University, Kunming 650500, China;
    2 School of Intelligent Science and Engineering, Yunnan Technology and Business University, Kunming 650201, China
  • Received:2025-02-25 Revised:2025-04-30 Accepted:2025-05-07 Online:2025-08-21 Published:2025-09-04
  • Contact: Shukang Deng E-mail:skdeng@126.com
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 62464013).

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摘要： This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method. A KCl flux-assisted high-temperature melting and slow-cooling strategy was employed to fabricate nanolayered Cu$_{2}$Se (KCl)$_{x}$ materials ($x =0$-3, denoted as S$_{0}$-S$_{3}$). Systematic characterization reveals that the coexistence of $\alpha $ and $\beta $ phases at room temperature creates favorable conditions for optimizing carrier transport. XPS analysis confirms the substitution of low-binding-energy Se$^{2-}$ by high-binding-energy Cl$^{-}$ ions within the lattice, effectively suppressing copper ion migration and remarkably improving the material's structural stability. Microstructural investigations demonstrate that all samples exhibit nanolayered stacking architectures abundant with edge dislocations. This multiscale defect architecture induces strong phonon scattering effects. Hall measurements indicate that the KCl flux-assisted processing facilitates the formation of highly ordered nanostructures, thereby enhancing carrier mobility and structural stability. Although the carrier concentration exhibits a slight decrease compared with the flux-free samples, the significant improvement in microstructural quality plays a crucial role in the synergistic optimization of electrical conductivity and the Seebeck coefficient. Notably, sample S$_{2}$ exhibited a considerable electrical conductivity, reaching approximately $1.0\times 10^{5}$ S$\cdot $m$^{-1}$ at 300 K. More strikingly, the cooperative effect of high-density edge dislocations and dopant atoms elevates material entropy, enabling sample S$_{3}$ to attain an ultralow lattice thermal conductivity of 0.55 W$\cdot $m$^{-1}\cdot $K$^{-1}$ at 350 K. Through multi-mechanism coordination, sample S$_{2}$ achieved a high ZT value of 1.45 at 700 K, representing a 2.7-fold improvement compared with traditional synthesis methods. This work provides new insights into performance optimization of liquid-like thermoelectric materials through defect engineering and entropy manipulation.

关键词: thermoelectric effects, low thermal conductivity, liquid-like, flux method

Abstract: This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method. A KCl flux-assisted high-temperature melting and slow-cooling strategy was employed to fabricate nanolayered Cu$_{2}$Se (KCl)$_{x}$ materials ($x =0$-3, denoted as S$_{0}$-S$_{3}$). Systematic characterization reveals that the coexistence of $\alpha $ and $\beta $ phases at room temperature creates favorable conditions for optimizing carrier transport. XPS analysis confirms the substitution of low-binding-energy Se$^{2-}$ by high-binding-energy Cl$^{-}$ ions within the lattice, effectively suppressing copper ion migration and remarkably improving the material's structural stability. Microstructural investigations demonstrate that all samples exhibit nanolayered stacking architectures abundant with edge dislocations. This multiscale defect architecture induces strong phonon scattering effects. Hall measurements indicate that the KCl flux-assisted processing facilitates the formation of highly ordered nanostructures, thereby enhancing carrier mobility and structural stability. Although the carrier concentration exhibits a slight decrease compared with the flux-free samples, the significant improvement in microstructural quality plays a crucial role in the synergistic optimization of electrical conductivity and the Seebeck coefficient. Notably, sample S$_{2}$ exhibited a considerable electrical conductivity, reaching approximately $1.0\times 10^{5}$ S$\cdot $m$^{-1}$ at 300 K. More strikingly, the cooperative effect of high-density edge dislocations and dopant atoms elevates material entropy, enabling sample S$_{3}$ to attain an ultralow lattice thermal conductivity of 0.55 W$\cdot $m$^{-1}\cdot $K$^{-1}$ at 350 K. Through multi-mechanism coordination, sample S$_{2}$ achieved a high ZT value of 1.45 at 700 K, representing a 2.7-fold improvement compared with traditional synthesis methods. This work provides new insights into performance optimization of liquid-like thermoelectric materials through defect engineering and entropy manipulation.

Key words: thermoelectric effects, low thermal conductivity, liquid-like, flux method

中图分类号:  (Thermoelectric effects)

  • 73.50.Lw
74.25.fc (Electric and thermal conductivity) 65.20.-w (Thermal properties of liquids) 06.60.Ei (Sample preparation)