Engineering Fuel Cell Electrodes to Overcome Ion Transport Limitations using Low-cost, Efficient Lignin-based Ionomers

为了减少温室气体排放，需要环保的、负担得起的电动汽车技术。一个有希望的解决方案是质子交换膜燃料电池(PEMFC)，这是一种以氢为燃料的电化学技术。然而，目前的质子交换膜燃料电池使用的是一种名为Nafion的离子导电聚合物，这种聚合物价格昂贵，而且不环保。最重要的是，Nafion无法有效地在薄层(覆盖催化剂和电极)中传输质子，这对PEMFC的性能产生了负面影响，并限制了现实世界的适用性。该项目旨在通过使用一种新型的环保、高效的离子导电聚合物来解决这些成本、性能和环境问题。这些聚合物将从木质素中提取，木质素是第二种天然含量最高的聚合物，存在于植物细胞壁中，是农业农场、纸浆和造纸工业以及生物炼油厂的副产品。在这个项目中，PI将使用植物来源的木质素来制造离子导电聚合物，并检查它们在薄层和界面中传输质子的能力，例如在PEMFC中发现的质子。该项目是以木质素为基础的离子导电聚合物取代Nafion的第一步，使PEMFC汽车比电池驱动的汽车更有效率和成本竞争力。该项目将向能源研究界介绍“使用绿色材料的绿色能源”的新概念，并为未来多样化的能源劳动力培训研究生、本科生和高中生。这项研究还将得到数据驱动的外展计划的补充，以支持整个内布拉斯加州的能源素养，将游戏化整合到课程中以激发学生的批判性思维，吸引K-12学生和普通公众扩大STEM的参与，并促进所有年龄段的人的能源教育。该项目的目标是通过利用木质素衍生的离聚体来克服离子传输限制，这是限制采用质子交换膜燃料电池(PEMFC)的主要科学挑战。该项目将研究如何通过使用基于木质素的离聚体和操纵亚微米厚离聚体层衬底附近的化学、分子和取向景观来促进界面离子传输。该项目将开辟加速界面电化学过程的新途径，方法包括：(1)阐明由一系列木质素基离聚体组成的薄膜和催化层模拟系统中的界面质子传输特性；(2)使用木质素基离聚体设计界面，以揭示其对特定深度离子传输特性的作用；以及(3)研究木质素磺酸离聚体仿电极薄膜系统中的质子传输如何受界面润湿、化学组成、离子结构特征、纳米结构和粘弹性性质的控制。所获得的知识将为理解和加快界面电化学过程铺平新的道路，使具有成本效益、环境友好和高效的能源转换/存储设备的设计成为可能，促进对被忽视的生物质木质素进行价值评估的创新方法，并有助于生物和能源经济。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Eco-friendly, affordable technologies for electric cars are needed to reduce greenhouse gas emissions. One promising solution is the proton exchange membrane fuel cell (PEMFC), an electrochemical technology that uses hydrogen as fuel. However, current PEMFCs use an ion-conducting polymer, called Nafion which is expensive and not eco-friendly. Most importantly, Nafion fails to transport protons efficiently in thin layers (coating the catalyst and electrode) which negatively impacts PEMFC performance and limits real world applicability. This project aims to address these cost, performance, and environmental concerns by using a new class of eco-friendly, efficient ion-conducting polymers. These polymers will be derived from lignin, the second most naturally abundant polymer that is found in plant cell walls and a waste byproduct of agricultural farms, pulp and paper industries, and biorefineries. In this project, the PI will use lignin from plant sources to make ion-conducting polymers and examine their ability to transport protons in thin layers and interfaces, such as those found in PEMFCs. This project is the first step to enable lignin-based ion-conducting polymers to replace Nafion, make PEMFC vehicles efficient and cost competitive to battery-powered vehicles. This project will introduce the energy research community to a new concept “Green Energy using Green Materials” and enable training of graduate, undergraduate, and high school students for a future diversified energy workforce. The research will also be complemented by data-driven outreach programs to support energy literacy across Nebraska, integrate gamification into courses to stimulate student critical thinking, engage K-12 students and the general public to broaden STEM participation, and facilitate energy education for people of all ages. The goal of this project is to overcome ion transport limitation, a major scientific challenge limiting the adoption of proton exchange membrane fuel cells (PEMFCs), by utilizing lignin-derived ionomers. The project will investigate how to boost interfacial ion transport by using lignin-based ionomers and manipulating the chemical, molecular, and orientational landscape next to the substrate of sub-micron-thick ionomer layers. The project will open new pathways to expedite interfacial electrochemical processes by (1) elucidating interfacial proton transport properties within thin films and catalyst layer mimicking systems made of a series of lignin-based ionomers; (2) engineering the interface using lignin-based ionomers to reveal their role on depth-specific ion transport properties; and (3) examining how proton transport in lignosulfonic acid ionomer-based electrode-mimicking thin systems is controlled by interfacial wetting, chemical composition, ionic domain characteristics, nanostructure, and viscoelastic properties. The gained knowledge will pave new ways to understand and expedite interfacial electrochemical processes, empower the design of cost-effective, eco-friendly, and efficient energy conversion/storage devices, promote innovative ways to valorize the neglected biomass lignin, and aid in both bio- and energy economy.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.