In this work, the ion transport of K⁺ and Li⁺ through angstrom-scale pores was thoroughly investigated using molecular dynamics (MD) simulation. Despite of their similar sizes, anomalously selective behaviors were observed. Our MD simulations found that the selectivities through two kinds of pores with diameters of 4 Å and 5 Å show an opposite preference on K⁺ or Li⁺ respectively under certain applied voltage. We demonstrated that the exchange of hydration shell with surrounding water molecules plays an important role in the ion mobility. Higher exchange rate equivalently reduces the apparent friction of the hydrated ion during its migration, thus increases the ion mobility. The interactions between ions and the pore edge also contribute to the ion mobility. Our results provide insights into the atomic scale details of ion transport process. Based on these findings, the applied voltage and pore size can be used to actively control the selectivity of K⁺/Li⁺ ions.

在这项工作中，使用分子动力学（MD）模拟彻底研究了K ⁺和Li ⁺通过埃级孔的离子迁移。尽管它们的大小相似，但观察到异常的选择性行为。我们的MD模拟发现，通过两种直径为4Å和5Å的孔的选择性对K ⁺或Li ⁺表现出相反的偏好分别在一定的施加电压下。我们证明水合壳与周围水分子的交换在离子迁移率中起重要作用。较高的交换速率等效地降低了水合离子在其迁移过程中的表观摩擦，因此增加了离子迁移率。离子与孔边缘之间的相互作用也有助于离子迁移率。我们的结果提供了对离子迁移过程的原子尺度细节的见识。基于这些发现，施加的电压和孔径可用于主动控制K ⁺ / Li ⁺离子的选择性。