Bang-Zhou Tian,Yi-Yan Liao,Fang Xu,Xiao-Ling Qiu,Fu-Jie Zhang,Ran Ang
Interfacial modulation has been considered an effective strategy to enhance the thermoelectric (TE) performance by decoupling thermal and electrical parameters. However, inappropriate interfacial heterojunctions can significantly deteriorate electrical transport while enhancing phonon scattering, which causes no substantial improvement in TE performance. Herein, we introduce two-dimensional graphene or MXene into the Mg3.2Sb0.5Bi1.49Te0.01 matrix by ball mixing combined with rapid sintering to modify the composition and structure at the interface. The differences in morphology, size and distribution of interfacial graphene and MXene lead to distinct results which show that incorporated graphene flakes with larger size hinder the carrier transport, while the homogeneously dispersed tiny MXene provides improved carrier channels and boosts the mobility. On the other hand, such uniformly diffused heterogeneous MXene structures create stronger scattering on phonons compared to enriched graphene phases, resulting in a low lattice thermal conductivity of ∼0.66 W m−1 K−1 and enhanced zT of ∼1.0 at 513 K in Mg3.2Sb0.5Bi1.49Te0.01-0.6 wt% MXene with good component stability in air. This work highlights the importance of size, concentration, and distribution in the interfacial modulation strategy, demonstrating an effective method for developing high TE performance Mg3(Sb, Bi)2-based near-room-temperature materials.
The n-type Mg3(Sb,Bi)2-based thermoelectric materials are promising candidates for medium-temperature power generation due to their low cost, nontoxicity, and high performance. However, their large-scale application in thermoelectric devices is significantly hindered by poor long-term stability, resulting from electrode interface degradation. Effective contact interfaces in thermoelectric devices require high bonding strength, low interfacial resistivity, and exceptional stability. Therefore, the development of efficient and reliable thermoelectric interface materials is crucial for the practical application of these devices. Conventional approaches to forming interfacial barrier layers mainly rely on thermodynamic equilibrium, which often overlook the critical roles of interfacial reactions and diffusion kinetics. In this study, molecular dynamics simulations were employed to uncover the underlying mechanisms responsible for the high stability of the Mg2Ni barrier layer and its interface with thermoelectric materials. The Mg2Ni/Mg3.21Sb1.5Bi0.5Y0.04 thermoelectric device exhibited excellent performance, with a low contact resistance of 11 μΩ·cm2, a high output power density of 1.2 W·cm–2, and an energy conversion efficiency of 5% at a temperature difference of ΔT = 373 K. This strategy is applicable to other thermoelectric materials, offering valuable insights for designing barrier layers in diverse thermoelectric systems.
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