Aqueous Electrolytes in Nanoporous Media: Structure, Dynamics and Electrochemo-Mechanical Actuation

纳米多孔介质中的水电解质：结构、动力学和电化学机械驱动

• 批准号: 509293944
• 负责人: Professor Dr. Michael Fröba
• 金额: --
• 依托单位: Institut für Anorganische und Angewandte Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/509293944?language=en
• 关键词: Aqueous; Electrolytes; Nanoporous; Media; Structure

An electrolyte solution near a charged solid surface forms an electric double layer (EDL). While the theory of EDLs has been known since the 1850s, their structure and dynamics are much less understood in the confined geometry of nanoporous media. There, large interfacial curvatures and overlapping EDLs of opposing interfaces can lead to significant property changes compared to planar geometries. Furthermore, EDL formation can lead to changes in mechanical interfacial stresses at the single pore scale and thus to macroscopic material deformation. In this project, this electrochemo-mechanical actuation will be related to the structure and dynamics of the EDL for aqueous electrolytes in nanoporous carbons. For this purpose, experiments and molecular simulation will be combined from the nanoscopic single-pore scale to the macroscopic scale of the porous medium.We will synthesize electrically conducting nanoporous carbons with high specific surface area, defined pore sizes (1-10 nm) and pore geometries. This will allow fine-tuning of the effect of the interfacial region compared to the rest of the pore volume. By adding heteroatoms to the carbon structure and controlling the defect concentrations, different surface chemistries (hydrophobic vs. hydrophilic) are introduced. Depending on the applied electrical voltage between electrolyte and solid, the surface chemistry and the pore diameter, we will investigate EDL formation and mechanical actuation in the material. We will focus on aqueous solutions of simple salts and investigate the role of salt concentration among other parameters. We will use synchrotron-based X-ray scattering to study the EDL in-operando, with special attention to the charge/discharge and thus ion transport kinetics. We will use molecular dynamics simulations to represent the structural properties of the surface of the nanoporous medium and the electrolyte. This should allow us to derive the structural, thermodynamic and transport properties of the geometrically confined electrolyte and relate them to the experimental results, both in terms of the electrochemo-mechanical couplings and the charge capacities at the scale of the single pore and the porous medium.In addition to these fundamental insights into aqueous electrolytes in geometric confinement, these studies provide the basis for supercapacitors with green, water-based electrolytes. They will also contribute to the development of materials for electromechanical actuators based on novel actuation principles, avoiding the usual piezoceramic systems that contain predominantly environmentally hazardous materials, such as lead.

带电固体表面附近的电解质溶液形成双电层（EDL）。虽然 EDL 理论自 1850 年代以来就为人所知，但在纳米多孔介质的受限几何形状中，人们对其结构和动力学的了解却少得多。在那里，与平面几何形状相比，大的界面曲率和相对界面的重叠 EDL 可能会导致显着的性能变化。此外，EDL 的形成会导致单孔尺度机械界面应力的变化，从而导致宏观材料变形。在该项目中，这种电化学机械驱动将与纳米多孔碳中水性电解质的 EDL 的结构和动力学相关。为此，实验和分子模拟将从纳米级单孔尺度到多孔介质的宏观尺度相结合。我们将合成具有高比表面积、确定的孔径（1-10 nm）和孔隙几何形状的导电纳米多孔碳。与其余孔体积相比，这将允许微调界面区域的效果。通过在碳结构中添加杂原子并控制缺陷浓度，引入了不同的表面化学性质（疏水性与亲水性）。根据电解质和固体之间施加的电压、表面化学和孔径，我们将研究材料中 EDL 的形成和机械驱动。我们将重点关注简单盐的水溶液，并研究盐浓度在其他参数中的作用。我们将使用基于同步加速器的 X 射线散射来研究 EDL 操作过程，特别关注充电/放电以及离子传输动力学。我们将使用分子动力学模拟来表示纳米多孔介质和电解质表面的结构特性。这应该使我们能够推导出几何限制电解质的结构、热力学和输运特性，并将它们与实验结果联系起来，无论是在电化学-机械耦合方面还是在单孔和多孔介质尺度的充电容量方面。除了对几何限制中水性电解质的这些基本见解之外，这些研究还为具有绿色、 水基电解质。他们还将致力于开发基于新颖驱动原理的机电驱动器材料，避免使用主要含有铅等对环境有害的材料的常见压电陶瓷系统。