标题： 离子液体的微分电容，根据具有最近邻相互作用的格子气体平均场模型 显示英文标题

标题： Differential capacitance of ionic liquids according to lattice-gas mean-field model with nearest-neighbor interactions

摘要： Bragg-Williams自由能被用于将最近邻相互作用引入到无溶剂离子液体在平面电极附近的格子气体模型中。 我们从平均场一致性关系的解中计算微分电容，在弱带电电极的极限情况下得出一个显式表达式。 理论中出现的两个额外材料参数——非理想度和每种离子类型的浓度变化阻力——导致了不同的区域，我们对其进行了识别和讨论。 当非理想度参数增加，该参数对于同电荷离子之间更强的最近邻吸引力会变得更加正，同时电极弱带电时，预测微分电容将经历发散，并在离子液体变得结构不稳定之前呈现出负值。 这与在零电位下电极的自发充电有关。 微分电容的发散和负号的物理起源是表面电势和表面电荷密度之间的非单调关系，这反映了在电极附近交替富集反离子和共离子的层状域的形成。 这种层状域模式的衰减长度可以比离子尺寸大很多倍，类似于最近提出的“欠屏蔽”概念。 显示英文摘要

摘要： The Bragg-Williams free energy is used to incorporate nearest-neighbor interactions into the lattice gas model of a solvent-free ionic liquid near a planar electrode. We calculate the differential capacitance from solutions of the mean-field consistency relation, arriving at an explicit expression in the limit of a weakly charged electrode. The two additional material parameters that appear in the theory -- the degree of nonideality and the resistance to concentration changes of each ion type -- give rise to different regimes that we identify and discuss. As the nonideality parameter, which becomes more positive for stronger nearest-neighbor attraction between like-charged ions, increases and the electrode is weakly charged, the differential capacitance is predicted to transition through a divergence and subsequently adopt negative values just before the ionic liquid becomes structurally unstable. This is associated with the spontaneous charging of an electrode at vanishing potential. The physical origin of the divergence and the negative sign of the differential capacitance is a nonmonotonic relationship between surface potential and surface charge density, which reflects the formation of layered domains alternatingly enriched in counterions and coions near the electrode. The decay length of this layered domain pattern, which can be many times larger than the ion size, is reminiscent of the recently introduced concept of "underscreening".