Atomic-scale investigation of enhanced lithium, sodium and magnesium storage performance from defects in MoS2/graphene heterostructures,Nanoscale

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Atomic-scale investigation of enhanced lithium, sodium and magnesium storage performance from defects in MoS2/graphene heterostructures
Nanoscale ( IF 5.8 ) Pub Date : 2020/02/26 , DOI: 10.1039/c9nr09352d
Ke Xu _{1,

2,

3,

4} , Ningbo Liao _{1,

2,

3,

4} , Miao Zhang _{1,

2,

3,

4} , Wei Xue _{1,

2,

3,

4}

Affiliation

MoS₂ is of great interest as an anode material of batteries due to its high theoretical reversible capacity; in particular, a defective MoS₂/graphene heterostructure exhibits excellent cycling stability. However, very little is known about the diffusion and ion storage mechanism at the atomistic level. To provide insights into the issue, we have developed and used first principles calculations and an atom intercalation/deintercalation algorithm to model the adsorption, diffusion, insertion and removal of Li, Na and Mg in pristine and defective MoS₂/graphene systems. First, the adsorption of Li, Na and Mg is generally more stable in the defective MoS₂/graphene structure. Mg and Li prefer to diffuse in the structure with disulfide defects, while Na prefers to diffuse in the molybdenum defective structure. Next, we found that the atomic configurations of both pristine and defective MoS₂/graphene are not restored to their original states after the insertion and removal of Li, Na and Mg, which is related to the irreversible capacity loss of the system. Furthermore, by excluding the amount of lithium atoms related to the unrestored sulfur atoms, an algorithm was proposed to calculate the reversible capacity and it was verified by experimental results. We have also demonstrated that the introduction of defects leads to significant increase in the theoretical capacities of the Na and Mg systems, however, decreasing the capacity retention rate of Mg.

中文翻译：

MoS2 /石墨烯异质结构缺陷增强锂，钠和镁储存性能的原子尺度研究

MoS ₂具有很高的理论可逆容量，因此作为电池的负极材料备受关注。特别地，有缺陷的MoS ₂ /石墨烯异质结构表现出优异的循环稳定性。但是，对于原子级的扩散和离子存储机理知之甚少。为了提供对该问题的见解，我们开发并使用了第一性原理计算和原子嵌入/脱嵌算法来模拟原始和有缺陷的MoS ₂ /石墨烯系统中Li，Na和Mg的吸附，扩散，插入和去除。首先，在有缺陷的MoS _2中，Li，Na和Mg的吸附通常更稳定/石墨烯结构。Mg和Li更喜欢在具有二硫化物缺陷的结构中扩散，而Na更喜欢在钼的缺陷结构中扩散。接下来，我们发现，在插入和去除Li，Na和Mg之后，原始的和有缺陷的MoS ₂ /石墨烯的原子构型都无法恢复到其原始状态，这与系统不可逆的容量损失有关。此外，通过排除与未还原的硫原子有关的锂原子的数量，提出了一种计算可逆容量的算法，并通过实验结果进行了验证。我们还证明，引入缺陷会导致Na和Mg系统的理论容量显着增加，但是会降低Mg的容量保持率。

更新日期：2020-04-03

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