University of Belgrade - Faculty of Physical Chemistry, Studentski trg 12-16, 11158 Belgrade, Serbia.
Phys Chem Chem Phys. 2018 May 23;20(20):13934-13943. doi: 10.1039/c8cp00992a.
New electrode materials for alkaline-ion batteries are a timely topic. Among many promising candidates, V2O5 is one of the most interesting cathode materials. While having very high theoretical capacity, in practice, its performance is hindered by its low stability and poor conductivity. As regards the theoretical descriptions of V2O5, common DFT-GGA calculations fail to reproduce both the electronic and crystal structures. While the band gap is underestimated, the interlayer spacing is overestimated as weak dispersion interactions are not properly described within GGA. Here we show that the combination of the DFT+U method and semi-empirical D2 correction can compensate for the drawbacks of the GGA when it comes to the modelling of V2O5. When compared to common PBE calculations, with a modest increase in the computational cost, PBE+U+D2 fully reproduced the experimental band gap of V2O5, while the errors in the lattice parameters are only a few percent. Using the proposed PBE+U+D2 methodology we studied the doping of V2O5 with 3d elements (from Sc to Zn). We show that both the structural and electronic parameters are affected by doping. Most importantly, a significant increase in conductivity is expected upon doping, which is of great importance for the application of V2O5 in metal-ion batteries.
用于碱性离子电池的新型电极材料是一个及时的话题。在许多有前途的候选材料中，V2O5 是最有趣的阴极材料之一。虽然具有非常高的理论容量，但实际上，其性能受到低稳定性和差导电性的限制。关于 V2O5 的理论描述，常见的 DFT-GGA 计算未能重现电子和晶体结构。虽然带隙被低估，但层间距被高估，因为 GGA 不能正确描述弱色散相互作用。在这里，我们表明，DFT+U 方法与半经验 D2 校正的结合可以弥补 GGA 在 V2O5 建模方面的缺点。与常见的 PBE 计算相比，在计算成本略有增加的情况下，PBE+U+D2 完全重现了 V2O5 的实验带隙，而晶格参数的误差仅为百分之几。使用所提出的 PBE+U+D2 方法，我们研究了 3d 元素（从 Sc 到 Zn）对 V2O5 的掺杂。我们表明，掺杂会影响结构和电子参数。最重要的是，预计掺杂会导致导电性显著提高，这对于 V2O5 在金属离子电池中的应用非常重要。
