CAREER: Micro-structured scaffolds for through-plane porous electrode diagnostics and design

PI：Shawn E.LitsterInstitution：卡内基梅隆大学提案编号：1053752标题：Career：用于贯穿平面的多孔电极诊断和设计的微结构支架解决石油安全和温室气体排放问题的障碍之一是替代汽车燃料电池和电池的成本和耐用性。制造和器件模型预测，质子交换膜燃料电池(PEMFC)和锂离子(Li-ion)电池的新电极结构具有优越的反应物传输性能，可以从根本上降低成本。目前，由于缺乏现场测量，识别最佳结构受到阻碍，限制了对电化学和传输现象的微米和纳米尺度耦合的科学理解。为了推动替代车辆和多孔电极科学的发展，需要现场电极诊断来揭示限制机制，测试理论模型，并指导未来的设计。PI计划使用微结构电极支架(MES)诊断技术建立微米级的多孔电极原位分析，并将其应用于推进燃料电池和电池电极的科学和工程。MES是一种多层平面衬底，它围绕着垂直的电极柱，并包含空间上分离的薄膜传感材料层(例如，铂超微电极)，这些薄膜传感材料层与电极S侧相交，并延伸到外部仪器。PI有一些初步的结果，包括首次对PEMFC阴极内的离子势和氧进行了空间分辨测量。计划中的教育和外联计划旨在招募代表性不足的群体进入工程学，并为通过车辆电气化扩大电化学技术的工程师做好准备。智能优点：MES诊断具有变革性，因为它们打开了以前无法接触到的电极内部，以直接进行现场测量。现有的诊断方法不能非侵入性地探测多孔电极的厚度，因为有源层很难接触到，而且非常薄。现场MES诊断允许典型的通过平面传输；测量通过平面的电位、电流和浓度的空间分布；可以达到1微米的分辨率；并且具有广泛的适用性。通过MES诊断，PI将解决有关传输和电化学耦合以及最优电极结构的关键科学和工程问题，包括：(1)识别和量化PEMFC电极中不同的传输阻力和退化机制，测试几个假设；(2)使用功能贯通平面分级和MES数据，识别改善传输的成分和结构的分布；(3)验证和改进领先的团聚和孔尺度模型；(4)确定新的无铂电极架构，以克服当前版本的严重传输损失(如果它们变得可行，无铂电极将从根本上改变燃料电池的经济性)；(5)将MES方法扩展到锂离子电池，以阐明并最小化其决定成本的传输阻力。更广泛的影响：凭借其新的测量能力和广泛的适用性(例如，对超级电容器)，MES方法将对多孔电极的研究产生影响。燃料电池和电池研究应对这些挑战，这些挑战支持广泛的未来替代汽车，以减少对石油的依赖和排放，并支持其他关键应用(例如，可再生能源储存)。S的教育和推广计划的主要影响是：(1)卡内基梅隆大学和其他地方的工程专业学生为未来过渡到使用新的？电化学板？教学方法和设备(BESA)，通过实践和项目增强学习来加强关于能源系统和电化学设备的教育。一个关键的重点是可转移到其他机构。(2)招募代表不足的群体进入工程学，在社区活动和服务不足的学校与便携式BESA进行互动外展活动？什么是工程学？为教师举办的讲习班。

PI: Shawn E. LitsterInstitution: Carnegie Mellon University Proposal Number: 1053752Title: CAREER: Micro-structured scaffolds for through-plane porous electrode diagnostics and design Among the barriers to addressing oil security and greenhouse gas emissions are the cost and durability of fuel cells and batteries for alternative vehicles. Manufacturing and device models forecast that proton exchange membrane fuel cell (PEMFC) and lithium-ion (Li-ion) battery costs can be radically reduced with new electrode architectures having superior reactant transport properties. Presently, identifying optimal architectures is hampered by a lack of in situ measurements, limiting scientific understanding of the micro- and nano-scale coupling of electrochemistry and transport phenomena. To advance alternative vehicles and porous electrode science, in situ electrode diagnostics are needed to reveal limiting mechanisms, test theoretical models, and guide future designs. The PI plans to establish micron-scale in situ analysis of porous electrodes using micro-structured electrode scaffold (MES) diagnostics and to apply them in advancing the science and engineering of fuel cell and battery electrodes. An MES is a multi-layer, planar substrate that surrounds a perpendicular column of electrode and contains spatially separated layers of thin-film sensing materials (e.g., Pt ultra-microelectrodes) that intersect the electrode?s side and extend to external instrumentation. The PI has some preliminary results, including the first spatially resolved measurements of ionic potential and oxygen within a PEMFC cathode. The planned education and outreach plan aims to recruit underrepresented groups into engineering and to prepare engineers for the expansion of electrochemical technology with vehicle electrification. Intellectual merit: MES diagnostics are transformative in that they open the previously inaccessible electrode internals to direct in situ measurements. Existing diagnostics are not able to probe non-intrusively across the thickness of porous electrodes because the active layers are difficult to access and are very thin. In situ MES diagnostics allow representative through-plane transport; measure through-plane spatial distributions of potentials, currents, and concentrations; can achieve 1 micrometer resolution; and are broadly applicable. With MES diagnostics, the PI will address key scientific and engineering questions on coupling of transport and electrochemistry and the architecture of optimal electrodes, including: (1) identify and quantify the distinct transport resistances and degradation mechanisms in PEMFC electrodes, testing several hypotheses; (2) using functional through-plane grading and MES data, identify distributions of composition and structure that improve transport; (3) validate and advance leading agglomerate and pore-scale models; (4) identify new Pt-free electrode architectures that overcome the severe transport losses of current versions (if they become viable, Pt-free electrodes will radically alter fuel cell economics); (5) extend MES methods to Li-ion batteries to elucidate and minimize their cost-dictating transport resistances. Broader impact: With their new measurement capabilities and broad applicability (e.g., to ultra-capacitors), MES methods will have impact on porous electrode research. The fuel cell and battery research addresses those challenges that support a wide range of future alternative vehicles to reduce oil reliance and emissions as well as supporting other key applications (e.g., renewable energy storage). The education and outreach plan?s key impacts are: (1) Preparing engineering students at Carnegie Mellon and beyond for future transitions to electrochemical power with a new ?breadboard? pedagogical approach and apparatus (BESA) that enhances education on energy systems and electrochemical devices with hands-on and project enhanced learning. A key emphasis is transferability to other institutions. (2) Recruiting underrepresented groups into engineering with interactive outreach activities with the portable BESA at community events and underserved schools and by ?What is Engineering?? workshops for teachers.