Wu Yecun, Wang Jingyang, Li Yanbin, Zhou Jiawei, Wang Bai Yang, Yang Ankun, Wang Lin-Wang, Hwang Harold Y, Cui Yi
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
Nat Commun. 2022 May 30;13(1):3008. doi: 10.1038/s41467-022-30516-z.
Lithium intercalation of MoS is generally believed to introduce a phase transition from H phase (semiconducting) to T phase (metallic). However, during the intercalation process, a spatially sharp boundary is usually formed between the fully intercalated T phase MoS and non-intercalated H phase MoS. The intermediate state, i.e., lightly intercalated H phase MoS without a phase transition, is difficult to investigate by optical-microscope-based spectroscopy due to the narrow size. Here, we report the stabilization of the intermediate state across the whole flake of twisted bilayer MoS. The twisted bilayer system allows the lithium to intercalate from the top surface and enables fast Li-ion diffusion by the reduced interlayer interaction. The E Raman mode of the intermediate state shows a peak splitting behavior. Our simulation results indicate that the intermediate state is stabilized by lithium-induced symmetry breaking of the H phase MoS. Our results provide an insight into the non-uniform intercalation during battery charging and discharging, and also open a new opportunity to modulate the properties of twisted 2D systems with guest species doping in the Moiré structures.
人们普遍认为，锂嵌入二硫化钼会引发从H相（半导体）到T相（金属）的相变。然而，在嵌入过程中，在完全嵌入的T相二硫化钼和未嵌入的H相二硫化钼之间通常会形成一个空间上清晰的边界。由于尺寸狭窄，基于光学显微镜的光谱难以研究中间状态，即未发生相变的轻度嵌入H相二硫化钼。在此，我们报告了在扭曲双层二硫化钼的整个薄片中中间状态的稳定化。扭曲双层系统允许锂从顶表面嵌入，并通过降低的层间相互作用实现快速锂离子扩散。中间状态的E拉曼模式表现出峰分裂行为。我们的模拟结果表明，中间状态通过锂诱导的H相二硫化钼对称性破缺而得以稳定。我们的结果为深入了解电池充放电过程中的不均匀嵌入提供了思路，也为通过在莫尔结构中掺杂客体物种来调节扭曲二维系统的性质开辟了新机会。
