Processing of Advanced Foam Scaffolds for Iron-Air Battery Applications

用于铁-空气电池应用的先进泡沫支架的加工

• 批准号: 1562941
• 负责人: David Dunand
• 金额: $ 32.06万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1562941&HistoricalAwards=false
• 关键词: Processing; Advanced; Foam; Scaffolds; Iron

The generation, storage, and local use of hydrogen to generate electric power via fuel cells are critical to reaching an electrical grid with low-to-zero carbon dioxide emissions, benefiting the U.S. economy and worldwide society. In recent years, iron oxide powder has attracted attention as an inexpensive, non-toxic option to store and create pure hydrogen through the iron-oxide reduction/oxidation ("redox") reaction. One of the main problems associated with this cyclical redox reaction is powder pulverization and subsequent agglomeration and consolidation. These effects drastically reduce the high surface areas needed for the reaction. Thus, maintaining stability, high surface area and high gas permeability in the powder bed after multiple redox cycles are the main challenges for this promising technology. This award supports research to develop a structure that takes advantage of novel processing approaches to create iron scaffolds which can maintain structural integrity, high permeability and high surface area during the redox cycles, thus enabling a novel, inexpensive and non-toxic iron-air battery for large scale use.In this research program, the investigators will directionally freeze an aqueous suspension of iron oxide nanopowders to create ice dendrites, which will push the particles into interdendritic space, thus creating a network of iron oxide powders walls. After hydrogen reduction, this network is sintered into a continuous scaffold with directionally aligned channels templating the original ice dendrites, surrounded by iron walls with high surface area and enough internal free space to achieve the microstructural stability needed to withstand multiple reduction/oxidation cycles without sintering or pulverization. The scaffold stability will be further improved by adding various materials to the iron oxide nanopowder suspension: (i) nickel oxide powders which are co-reduced to form iron-nickel solid solution walls with higher strength; (ii) space-holder powders such as strontium fluoride, which can be evaporated from the scaffold walls to generate further porosity within the walls and increase their surface area and the free volume to accommodate volume changes and (iii) inert reinforcements such as ceramic particles, which will strengthen and stiffen the scaffold walls. Mechanical testing will be used to examine relative structural degradation of samples after reduction/oxidation cycles, and x-ray tomography and finite element modeling will be used to map and examine 3-dimensional scaffold structure and stress distribution within its walls during the volumetric changes associated with the redox cycles.

通过燃料电池产生、储存和本地使用氢气来发电对于实现二氧化碳排放量低至零的电网至关重要，从而造福美国经济和全球社会。近年来，氧化铁粉末作为一种廉价、无毒的选择，通过氧化铁还原/氧化（“氧化还原”）反应来储存和产生纯氢而引起了人们的关注。与这种循环氧化还原反应相关的主要问题之一是粉末粉碎以及随后的附聚和固结。这些效应大大减少了反应所需的高表面积。 因此，在多次氧化还原循环后保持粉末床的稳定性、高表面积和高透气性是这项有前途的技术的主要挑战。该奖项支持研究开发一种结构，利用新颖的加工方法来创建铁​​支架，该铁支架可以在氧化还原循环过程中保持结构完整性、高渗透性和高表面积，从而实现新型、廉价且无毒的铁空气电池的大规模使用。在该研究项目中，研究人员将定向冷冻氧化铁纳米粉末的水悬浮液以形成冰枝晶，从而将颗粒推入 枝晶间空间，从而形成氧化铁粉末壁网络。氢还原后，该网络被烧结成连续支架，该支架具有定向排列的通道，以原始冰枝晶为模板，周围是具有高表面积和足够内部自由空间的铁壁，以实现承受多次还原/氧化循环所需的微观结构稳定性，而无需烧结或粉碎。通过在氧化铁纳米粉末悬浮液中添加各种材料，将进一步提高支架稳定性：（i）氧化镍粉末，共还原形成具有更高强度的铁镍固溶体壁； (ii) 空间保持粉末，如氟化锶，它可以从支架壁上蒸发，在壁内产生进一步的孔隙度，并增加其表面积和自由体积以适应体积变化；(iii) 惰性增强材料，如陶瓷颗粒，它将强化和硬化支架壁。机械测试将用于检查还原/氧化循环后样品的相对结构降解，X射线断层扫描和有限元建模将用于绘制和检查与氧化还原循环相关的体积变化期间的3维支架结构和其壁内的应力分布。