Collaborative Research: Understanding the Role of Directional Porosity in Transport and Mechanical Properties of Hierarchical Sintered Metal Oxide Electrodes

固态电池为无数的应用提供了动力，它们的制造和应用对美国的经济、健康和繁荣产生了重大影响。这些电池中的电极通常由复合材料制成，其中每种材料都发挥作用：电活性材料储存和传递能量，导电添加剂携带电子，聚合物粘合剂将组件固定在一起并提供机械坚固性。如果可以使用单一的多功能材料相作为电极，这些电池材料的能量存储和功率容量将大大增加。多孔陶瓷薄膜材料已被开发用于这一应用，但在电化学反应过程中，离子通过这些陶瓷的传输特性，它们的机械性能，或这些多功能作用与所产生的性能之间的权衡，人们知之甚少。该奖项支持基础研究，以了解由单一烧结多孔薄膜作为活性材料组成的电极的特性。这项研究有可能为多功能分层材料提供一个新的范例，从根本上改变这些材料的设计和加工方式。这项工作将为理解电化学活性和离子导电多孔陶瓷提供一个框架，它不仅在电池中有应用，而且在固体氧化物燃料电池和电化学传感器等其他设备中也有应用。在这个合作研究项目中，研究人员将测试浓度极化和离子传输限制烧结多功能电极的电化学电流密度的假设。为了调整电极的力学性能并实现可调的低扭曲度烧结电极，采用了一种新的冰模板加工方法来生产有序结构的电极和具有可调尺寸的定向孔。这将使系统研究可调定向孔隙度对离子传输和机械性能的影响成为可能。冰模板电极的微观结构对其力学性能，特别是抗压强度的详细影响将被研究。此外，还将研究其力学性能和电化学性能之间的耦合关系。假设较高的陶瓷片间桥密度可以提高机械强度，但代价是增加挠度和限制运输。这项工作研究了陶瓷加工过程中传输和机械性能之间的权衡，目的是了解高性能电极材料的加工-微观结构-性能关系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Solid state batteries provide power for countless applications, and their manufacture and application has significant impact on the US economy, health and prosperity. The electrodes in these batteries are conventionally made of composites where each material plays a role: an electroactive material stores and delivers energy, conductive additives carry electrons, and polymer binders hold the components together and provide mechanical robustness. If instead a single multifunctional material phase could be used as the electrode, the energy storage and power capacity of these battery materials would be greatly increased. Porous ceramic thin film materials have been developed for this application, but little is known about the transport properties of ions through these ceramics during electrochemical reactions, their mechanical properties, or the tradeoffs between these multifunctional roles and resulting properties. This award supports fundamental research to understand the properties of electrodes comprised of a single sintered porous thin film as the active material. This research has the potential to provide a new paradigm for multifunctional hierarchical materials which would fundamentally change the way these materials are designed and processed. This work will provide a framework for understanding electrochemically active and ion-conducting porous ceramics, which have application not only in batteries, but also in other devices such as solid oxide fuel cells and electrochemical sensors.In this collaborative research program, the researchers will test the hypothesis that concentration polarization and ion transport limits the electrochemical current density of sintered multifunctional electrodes. To tune the mechanical properties of electrodes and to achieve tunable, low tortuosity in sintered electrodes, a novel ice-templating processing approach is used to produce electrodes of ordered structure, and directional pores with tunable dimensions. This will enable systematic investigation of the impact of tunable directional porosity on both ionic transport and mechanical properties. The detailed impact of microstructure of the ice-templated electrodes on resulting mechanical properties, especially compressive strength, will be studied. In addition, the coupling between mechanical and electrochemical properties will be investigated. Higher bridge density between ceramic lamellae is hypothesized to improve mechanical strength, but at the expense of increased tortuosity and restricted transport. This work investigates the tradeoffs between transport and mechanical properties as a result of ceramic processing, with the objective of understanding the processing-microstructure-property relationships for high-performance electrode materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.