Transition metal dichalcogenides, such as ${\mathrm{MoS}}_2$, are known to undergo a structural phase transformation as well as a change in the electronic conductivity upon Li intercalation. These properties make them candidates for charge-tunable ion-insertion materials that could be used in electrochemical devices. In this paper, we study the phase stability and electronic structure of H and T' Li-intercalated $\mathrm{Mo}{X}_2$ bilayers with X = S, Se, or Te. Using first-principles calculations in combination with classical and machine learning modeling approaches, we find that the H phase is more stable at low Li concentration for all X and the critical Li concentration at which the T'$\to \mathrm{H}$ transition occurs decreases with increasing mass of X. Furthermore, the relative free energy of the two phases becomes less sensitive to Li insertion with increasing atomic mass of the chalcogen atom X. While the electronic conductivity increases with increasing ion concentration at low concentrations, we do not observe a (positive) conductivity jump at the phase transition from H to T'.

中文翻译：

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调整 MoX2（X=S、Se 或 Te）双层相变的临界锂嵌入浓度

过渡金属二硫属化物，例如 ${\mathrm{硫化钼}}_2$，已知在锂嵌入时经历结构相变以及电子电导率的变化。这些特性使它们成为可用于电化学设备的电荷可调离子插入材料的候选材料。在本文中，我们研究了 H 和 T' Li 插层的相稳定性和电子结构。$莫{十}_2$X  = S、Se 或 Te 的双层。使用第一性原理计算并结合经典和机器学习建模方法，我们发现 H 相在所有X 的低锂浓度和 T' 的临界锂浓度下更稳定。$\to \mathrm{H}$转变发生随着X质量的增加而减少。此外，随着硫族原子X 的原子质量增加，两相的相对自由能对 Li 插入变得不那么敏感。虽然在低浓度下电子电导率随着离子浓度的增加而增加，但我们没有观察到从 H 到 T' 的相变处的（正）电导率跳跃。