Mo2C as a high capacity anode material: a first-principles study
Mo2C as a high capacity anode material: a first-principles study
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DOI：
10.1039/c6ta01918h
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发表时间：
2016-01-01
影响因子：
11.9
通讯作者：
Peeters, Francois M.
中科院分区：
文献类型：
--
作者：
Cakir, Deniz;Sevik, Cem;Peeters, Francois M.
用第一性原理方法系统研究了Li、Na、K和Ca原子在Mo_2C单分子膜上的吸附和扩散。我们发现，所考虑的金属原子强烈绑定到Mo 2C单层。然而，这些碱金属和碱土金属元素的吸附能随着覆盖度的增加而降低，这是由于金属离子之间的排斥增强。我们预测一个显着的电荷转移从广告原子的Mo 2C单层，这清楚地表明金属原子的阳离子状态。原始和掺杂的Mo 2C的金属特性确保了良好的电子传导，这对于最佳阳极材料至关重要。低迁移能垒预测为43 meV的锂，19 meV的钠和15 meV的K，这导致这些原子在Mo 2C上的非常快的扩散。对于Mo_2C，我们发现了一个存储容量大于400 mA·h·g（-1）的多层吸附的列入。即使在高浓度下，Mo 2C在Li和Na沉积时也会轻微膨胀，这确保了原子层的良好循环稳定性。计算出的Li离子的平均电压为0.68 V，Na离子的平均电压为0.30 V，这使得Mo 2C对于低充电电压应用具有吸引力。
The adsorption and diffusion of Li, Na, K and Ca atoms on a Mo2C monolayer are systematically investigated by using first principles methods. We found that the considered metal atoms are strongly bound to the Mo2C monolayer. However, the adsorption energies of these alkali and earth alkali elements decrease as the coverage increases due to the enhanced repulsion between the metal ions. We predict a significant charge transfer from the ad-atoms to the Mo2C monolayer, which indicates clearly the cationic state of the metal atoms. The metallic character of both pristine and doped Mo2C ensures a good electronic conduction that is essential for an optimal anode material. Low migration energy barriers are predicted as small as 43 meV for Li, 19 meV for Na and 15 meV for K, which result in the very fast diffusion of these atoms on Mo2C. For Mo2C, we found a storage capacity larger than 400 mA h g(-1) by the inclusion of multilayer adsorption. Mo2C expands slightly upon deposition of Li and Na even at high concentrations, which ensures the good cyclic stability of the atomic layer. The calculated average voltage of 0.68 V for Li and 0.30 V for Na ions makes Mo2C attractive for low charging voltage applications.