【摘要】 据报道,层状结构（二硒化钼）可以作为金属离子电池的电极材料,但是,对金属离子嵌入层状结构中的结构和扩散机制尚不明确。为探究此问题,通过第一性原理计算,系统地研究了金属离子（锂、钠、镁和锌离子）电池中MoSe₂电极的扩散机制和结构变化。首先,通过计算其吸附能,发现锂离子和钠离子因具有强吸附能（0 eV～1.87 eV）而储存在MoSe₂阳极材料中;而MoSe₂对镁和锌等二价离子的吸附能力较弱,导致其储离子能力较低。其次,通过分析嵌离子后电荷密度的变化,可以发现金属离子和MoSe₂之间存在一定的电子转移,进而稳定嵌离子结构。此外,通过CINEB方法探究M离子的迁移能垒来分析金属电池的性能,计算结果表明,离子的迁移能垒大小依次为锌离子>镁离子>钠离子>锂离子。最后,通过引入应变,使其层状材料层间距增加,增加其扩散路径。通过第一性原理计算应变条件下吸附能和迁移能垒的变化规律,发现二价Mg和Zn离子的变化程度较大,迁移能垒有显著的降低。因此,应变可以改善MoSe₂电极在金属离子电池的应用效果,尤其是对镁和锌金属电池的效果更明显。更多还原

【Abstract】 According to reports, the layered structure（MoSe₂）could be used as an electrode material for metal ion batteries. However, the structure and diffusion mechanism of metal ions embedded in the layered structure have not been fully studied. To explore this problem, the first-principles calculations has used to systematically study the diffusion mechanism and structural changes of MoSe₂ electrodes in metal ion（Lithium,Sodium, Magnesium and Zinc ion）batteries. Firstly, by calculating its adsorption energy, it was found that Lithium and Sodium ions are stored in MoSe₂ anode material due to strong adsorption energy（0 eV～1. 87 eV）; while MoSe₂ has a weak adsorption capacity for such as Mg and Zn divalent ions, resulting in low ion storage ability. Secondly, by analyzing the change of the charge density after ion insertion, it could be found that there was a certain electron transfer between the metal ion and MoSe₂, thereby stabilizing the ion insertion structure. In addition, the CINEB method was used to explore the migration energy barrier of M ions to clarify the performance of metal batteries. And the calculation results show that the order of the energy barriers for ion migration was Zinc ion>Magnesium ion>Sodium ion>Lithium ion. Finally, by introducing strain,the spacing between layers of the layered material was increased, and the diffusion path was increased. By calculating the change law of adsorption energy and migration energy barrier under strain conditions by first principles, it was found that the degree of change of bivalent Mg and Zn ions was large, and the migration energy barrier was significantly reduced. Therefore, strain can improve the application of MoSe₂ electrodes in metal ion batteries, especially magnesium and zinc metal batteries.更多还原