Department of Physics, Laboratory of Computational Materials Physics, Jiangxi Normal University, Nanchang, 330022, China.
Phys Chem Chem Phys. 2019 Apr 3;21(14):7406-7411. doi: 10.1039/c9cp00528e.
The scarce inventory of cathode materials with reasonable diffusion of Mg ions is the main obstacle in the development of rechargeable magnesium batteries. In this regard, vanadium pentoxide (V2O5) has been reported to be a candidate cathode material for Mg batteries. In this study, via first-principles calculations, we showed that the Mg-ion diffusion energy barrier in α-V2O5 could be substantially decreased through hydrogenation. It is found that the Mg-ion migration energy barrier in HxV2O5 is gradually decreased with an increase in H concentration. When the H concentration x reaches 2, the migration barrier is decreased to 0.56 eV from that in α-V2O5 without hydrogenation (1.28 eV). This indicates that the Mg diffusion kinetics can be substantially improved through hydrogenation, and the resultant energy barrier makes Mg diffusion acceptable even at room temperature. The mechanism of the H-enhanced Mg-diffusion has also been studied, and it has been found that H atoms not only can expand the Mg-diffusion pathway, but also have a screening effect on the interactions between Mg ions and the α-V2O5 lattice.
具有合理镁离子扩散的阴极材料库存稀缺，这是可充电镁电池发展的主要障碍。在这方面，五氧化二钒 (V2O5) 已被报道为镁电池的候选阴极材料。在这项研究中，通过第一性原理计算，我们表明通过氢化可以显著降低 α-V2O5 中镁离子的扩散能垒。研究发现，在 HxV2O5 中，随着 H 浓度的增加，Mg 离子迁移能垒逐渐降低。当 H 浓度 x 达到 2 时，迁移势垒从没有氢化的 α-V2O5 中的 1.28 eV 降低到 0.56 eV。这表明通过氢化可以显著提高 Mg 的扩散动力学，并且由此产生的能量势垒使得即使在室温下，Mg 扩散也可以接受。还研究了 H 增强 Mg 扩散的机制，发现 H 原子不仅可以扩展 Mg 扩散途径，而且对 Mg 离子与 α-V2O5 晶格之间的相互作用具有屏蔽作用。
