Capacitive density functional theory for structure and screening in ionic fluids and electric double layers with applications in sustainability

用于离子液体和双电层结构和筛选的电容密度泛函理论及其在可持续发展中的应用

• 批准号: 406121234
• 负责人: Dr. Andreas Härtel
• 金额: --
• 依托单位: Institute for Theoretical Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/406121234?language=en
• 关键词: Capacitive; density; functional; theory; structure

The sustainable treatment of water and our demand of energy are challenges that we are facing at the beginning of the 21st century. Promising technologies addressing these challenges exploit the properties of ionic fluids and electric double layers (EDLs). The latter develop at the electrode-electrolyte interface when ionic electrolytes and supercapacitive (large surface) electrodes are combined. The physics of EDLs is crucial for the large capacitance of supercapacitive electrodes and for their utilization in energy harvesting, energy conversion, and deionization. In our proposed project we will develop a new theory in order to complete our knowledge of the properties of electrolytes and EDLs. Using this theory we will study structure and electrostatic screening which are relevant, not only for modeling and describing electrolytes and capacitive technologies, but also for related areas like chemistry (colloids) and biology (ion channels, DNA). To reach our goal, we will apply classical density functional theory (DFT), which is a microscopic framework in statistical physics. In particular, we will (i) give a solution for the long-standing problem of combining point-like Coulombic charges and steric hard-core repulsions in the primitive model of ions. The new approach is crucial to describe structural transitions in EDLs and, consequently, to understand the resulting anomalous capacitance of EDL-based electrodes. Furthermore, we will (ii) develop a new approach for explicit solvents in electrolytes and for modeling effective interactions in DFT. Based on this theoretical approach, we will study ionic hydration and the effect of dipolar solvent molecules, which are assumed to be the key ingredients for the description of an unexplained increase in the screening length that has been reported in experiments recently. Our research will be based on extensive numerical calculations. To this end, we will develop the state-of-the-art software package capDFT, which we will share with the public. Though, capDFT can serve as modeling software, especially in the applied sciences. Collaborations with leading scientists and joining conferences will help to disseminate our research and improve our scientific network.

水的可持续处理和我们对能源的需求是我们在21世纪世纪初面临的挑战。解决这些挑战的有前途的技术利用离子流体和双电层（EDL）的性质。当离子电解质和超级电容（大表面）电极组合时，后者在电极-电解质界面处发展。EDLs的物理特性对于超级电容电极的大电容以及它们在能量收集、能量转换和去离子中的利用至关重要。在我们提出的项目中，我们将开发一个新的理论，以完成我们的知识的性质的电解质和EDLs。利用这一理论，我们将研究结构和静电屏蔽，这不仅适用于建模和描述电解质和电容技术，而且适用于化学（胶体）和生物学（离子通道，DNA）等相关领域。为了达到我们的目标，我们将应用经典密度泛函理论（DFT），这是统计物理学中的微观框架。特别是，我们将（i）给出一个长期存在的问题相结合的点样库仑电荷和空间硬核排斥的原始模型的离子的解决方案。这种新方法对于描述EDL中的结构转变以及因此理解基于EDL的电极的异常电容至关重要。此外，我们将（ii）开发一种新的方法，明确的溶剂在电解质和有效的相互作用在DFT建模。基于这种理论方法，我们将研究离子水合作用和偶极溶剂分子的影响，这被认为是描述最近在实验中报道的屏蔽长度的原因不明的增加的关键成分。我们的研究将以大量的数值计算为基础。为此，我们将开发最先进的软件包capDFT，并与公众分享。尽管如此，capDFT可以作为建模软件，特别是在应用科学中。与领先的科学家合作并参加会议将有助于传播我们的研究并改善我们的科学网络。