We report on an extensive molecular simulations study about the influence of the nature of functional groups and anion size on the charging mechanisms and volume expansion/contraction in layered materials used as electrodes for energy storage applications. The study of the electrochemical behavior of graphene and Ti₃C₂ MXene (with three different functional groups) in five ionic liquids shows that the electrodes expand when charged negatively and no major dependence on the anion type is observed. When the electrode is positively charged, the volume changes are more complex and no specific trend could be observed depending on the anion size. The volume changes are in most cases, very well explained by the quantities of adsorbed ions. In specific cases, e.g., for FSI⁻ and TFSI⁻ anions, the reorientation of the ions can also affect the interlayer volume. We demonstrate that the charging mechanisms are changing consistently with the anion sizes and are largely correlated with the surface charge of the electrode material in the neutral state.

我们报告了一个广泛的分子模拟研究，该研究涉及官能团的性质和阴离子大小对用作能量存储应用电极的层状材料中的充电机理和体积膨胀/收缩的影响。对石墨烯和Ti ₃ C ₂ MXene（具有三个不同的官能团）在五种离子液体中的电化学行为的研究表明，当带负电时电极会膨胀，并且没有观察到对阴离子类型的主要依赖性。当电极带正电时，体积变化更为复杂，根据阴离子的大小，没有观察到特定的趋势。在大多数情况下，体积变化可以通过吸附离子的数量很好地解释。在特定情况下，例如，对于FSI ^-和TFSI ^-阴离子，离子的重新取向也可影响中间层的体积。我们证明，充电机制随着阴离子尺寸的变化而不断变化，并且与中性状态下电极材料的表面电荷高度相关。