Tang Xin, Ye Han, Liu Wenjun, Liu Yumin, Guo Zhenlin, Wang Mingchao
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications Beijing 100876 China
Mechanics Division, Beijing Computational Science Research Center Beijing 100193 China.
Nanoscale Adv. 2021 Mar 17;3(10):2902-2910. doi: 10.1039/d1na00112d. eCollection 2021 May 18.
Janus transition metal dichalcogenides with unique physical properties have recently attracted increasing research interest for their energy and catalytic applications. In this paper, we investigate the lithiation behavior of a square phase Janus MoSSe monolayer (1S-MoSSe) using first-principles calculations. Computational results show that a single Li atom energetically prefers to adsorb on the central site of the octagonal ring (O site) and on the S-layer side of 1S-MoSSe. The predicted energy barriers for Li diffusion are surface dependent and in the range of 0.33 to 0.51 eV, indicating the acceptable Li migration kinetics on 1S-MoSSe in comparison with other 2D TMD materials. Further thermodynamic analysis demonstrates that Li adsorption on 1S-MoSSe is energetically stable up to a Li concentration of = 1.0, above which the lithiation process becomes unstable with a negative charging potential. Phonon calculations also confirm that Li adsorption (0.25 ≤ ≤ 0.75) results in the lattice distortion of 1S-MoSSe in order to suppress the structural instability of the lithiated monolayer 1S-Li MoSSe with imaginary phonon frequencies. The less symmetric nature of 1S-MoSSe is believed to destabilize Li adsorption at much smaller than 1H-MoSSe does, regardless of the higher dipole moment of 1S-MoSSe. This computational study provides a fundamental understanding of the electrochemical performance of 1S-MoSSe, as well as useful insight into the material design of Janus TMD anodes for Li-ion batteries.
具有独特物理性质的Janus过渡金属二硫属化物最近因其在能源和催化方面的应用而吸引了越来越多的研究兴趣。在本文中，我们使用第一性原理计算研究了方形相Janus MoSSe单层（1S-MoSSe）的锂化行为。计算结果表明，单个锂原子在能量上更倾向于吸附在八边形环的中心位置（O位）以及1S-MoSSe的S层一侧。预测的锂扩散能垒与表面有关，范围在0.33至0.51 eV之间，这表明与其他二维过渡金属二硫属化物材料相比，1S-MoSSe上的锂迁移动力学是可以接受的。进一步的热力学分析表明，在锂浓度 = 1.0之前，锂在1S-MoSSe上的吸附在能量上是稳定的，高于此浓度，锂化过程会因负充电电位而变得不稳定。声子计算还证实，锂吸附（0.25≤≤0.75）会导致1S-MoSSe的晶格畸变，以抑制具有虚声子频率的锂化单层1S-Li MoSSe的结构不稳定性。尽管1S-MoSSe的偶极矩较高，但据信1S-MoSSe较不对称的性质会使锂在比1H-MoSSe小得多的情况下吸附变得不稳定。这项计算研究为1S-MoSSe的电化学性能提供了基本理解，也为锂离子电池的Janus过渡金属二硫属化物阳极的材料设计提供了有用的见解。
