超级电容器及锂电池中锂离子相互作用模型的构建

摘要

Lithium ions are highly concentrated in super capacitors and lithium battery, and to construct an accurate interaction model for lithium ions plays an important guiding role in predicting the performance of super capacitors and lithium battery and designing of electrode material. In this work, the interaction model was established for lithium ion in super capacitors and lithium battery by employing quantum density functional theory. It was focused on the characteristics and the solvation effect on the van der Waals interaction between lithium ions. It was revealed that the Coulombic repulsion was highly screened by the van der Waals interaction, and the solvation effect resulted a prodigious contribution to the van der Waals interaction. The molecular interaction model for lithium ion in different solvents was established by numerical fitting (primitive model). Besides, the three-body interaction for lithium ions was also considered and was revealed that the three-body interaction was an attraction, which was effective only when the ions were highly concentrated.%超级电容器及锂电池中锂离子高度富集，构建准确的锂离子相互作用模型对于预测超级电容器及锂电池性能、设计电极材料具有重要的指导作用。通过量子密度泛函理论计算了超级电容器及锂电池中锂离子间的相互作用，重点考察了锂离子间短程范德华相互作用的特点及溶剂化效应对范德华作用的影响，发现短程区域内范德华作用能在很大程度上屏蔽库仑排斥作用，溶剂化效应对范德华作用有很大贡献。通过数值拟合建立了能适用于不同溶剂环境下的锂离子相互作用分子模型(隐式溶剂模型)。另外还考察了锂离子间三体相互作用，发现三体相互作用为吸引作用，且仅对局部大量富集的锂离子有较大影响。