Alkaline Polymer Electrolyte Fuel Cells

第一个可行的大规模燃料电池系统是弗朗西斯·培根开发的液体电解质碱性燃料电池。直到最近，整个航天飞机都是由这种燃料电池提供动力的。这些燃料电池的主要困难在于液体电解质难以固定，并且由于形成低溶解度的碳酸盐物质而遭受问题。随后的材料发展导致质子交换膜（pemm，如Nafion(r)）的引入和著名的质子交换膜燃料电池（PEMFC）的发展。成本是阻碍pemfc商业化应用的主要因素，主要集中在3个关键部件上：(1)Pt催化剂（尽管进行了大量研发，但负载仍然很高）；（二）项目管理人员；(3)双极板材料（与超强酸Nafion接触后能存活的廉价材料很少）。由于电渗透阻力，pemfc内的水平衡难以优化。最后，基于pem的直接甲醇燃料电池（dmfc）由于甲醇迁移到阴极（电压损失和燃料浪费）而表现出性能下降。材料科学和化学的最新进展使膜材料和离聚体的生产成为可能，这将使碱当量的PEMs得以发展。这些碱性阴离子交换膜（AAEMs）的应用有望在燃料电池的可行性上实现巨大飞跃。申请团队包括这项创新技术开发的世界领导者。这种燃料电池（OH-阴离子而不是质子传导）提供了许多显著的优势：(1)燃料电池反应的催化在碱性条件下比酸性条件下更快——事实上，非铂催化剂在这种环境下表现得非常好，例如Ag用于氧还原。(2)许多材料在碱性环境中比在酸性环境中表现出耐腐蚀性。这增加了可以使用的材料的数量和化学性质（包括廉价，易于冲压和薄金属双极板材料）。(3)无氟离聚物是可行的，有望显著降低膜成本。(4)水和离子在oh -阴离子导电电解质中的传输是有利的，电渗透阻力将水从阴极传输（防止阴极上的泛水，这是pemfc和dmfc的一个主要问题）。这一过程也减轻了dmfc中的“交叉”问题。该研究项目包括开发一套实现碱性聚合物电解质膜燃料电池（APEMFC）所需的材料和技术。这项研究将由位于伦敦帝国理工学院、克兰菲尔德大学、纽卡斯尔大学和萨里大学的世界领先材料科学家、化学家和工程师组成的联盟进行。这个团队代表了可以进行此类研究的最佳团队之一，体现了对燃料电池系统各个方面的实验和理论水平的多尺度理解，从基本的电催化到堆叠水平，包括评估这些系统的诊断方法。研究小组已经探索了apemfc的一些方面，该项目将以综合、多管齐下的方式开发新技术的每个方面，同时将其正在进行的成果传达给相关工业合作伙伴俱乐部的成员。广泛的学科跳跃和国际水平的合作机会将被充分接受。总体目标是为apemfc开发膜材料、催化剂和离子单体，并利用无铂电催化剂构建和运行这种燃料电池。拟议的工作方案是冒险的：然而，风险已经过仔细评估，同时也有适当的缓解战略（高风险组成部分承诺高回报，但依赖关系很少）。成功将导致英国开创一种新的清洁能源转换技术。

The first viable large scale fuel cell systems were the liquid electrolyte alkaline fuel cells developed by Francis Bacon. Until recently the entire space shuttle fleet was powered by such fuel cells. The main difficulties with these fuel cells surrounded the liquid electrolyte, which was difficult to immobilise and suffers from problems due to the formation of low solubility carbonate species. Subsequent material developments led to the introduction of proton-exchange membranes (PEMs e.g. Nafion(r)) and the development of the well-known PEMFC. Cost is a major inhibitor to commercial uptake of PEMFCs and is localised on 3 critical components: (1) Pt catalysts (loadings still high despite considerable R&D); (2) the PEMs; and (3) bipolar plate materials (there are few inexpensive materials which survive contact with Nafion, a superacid). Water balance within PEMFCs is difficult to optimise due to electro-osmotic drag. Finally, PEM-based direct methanol fuel cells (DMFCs) exhibit reduced performances due to migration of methanol to the cathode (voltage losses and wasted fuel).Recent advances in materials science and chemistry has allowed the production of membrane materials and ionomers which would allow the development of the alkaline-equivalent to PEMs. The application of these alkaline anion-exchange membranes (AAEMs) promises a quantum leap in fuel cell viability. The applicant team contains the world-leaders in the development of this innovative technology. Such fuel cells (conduction of OH- anions rather than protons) offer a number of significant advantages:(1) Catalysis of fuel cell reactions is faster under alkaline conditions than acidic conditions - indeed non-platinum catalysts perform very favourably in this environment e.g. Ag for oxygen reduction.(2) Many more materials show corrosion resistance in alkaline than in acid environments. This increases the number and chemistry of materials which can be used (including cheap, easy stamped and thin metal bipolar plate materials).(3) Non-fluorinated ionomers are feasible and promise significant membrane cost reductions.(4) Water and ionic transport within the OH-anion conducting electrolytes is favourable electroosmotic drag transports water away from the cathode (preventing flooding on the cathode, a major issue with PEMFCs and DMFCs). This process also mitigates the 'crossover' problem in DMFCs.This research programme involves the development of a suite of materials and technology necessary to implement the alkaline polymer electrolyte membrane fuel cells (APEMFC). This research will be performed by a consortium of world leading materials scientists, chemists and engineers, based at Imperial College London, Cranfield University, University of Newcastle and the University of Surrey. This team, which represents one of the best that can be assembled to undertake such research, embodies a multiscale understanding on experimental and theoretical levels of all aspects of fuel cell systems, from fundamental electrocatalysis to the stack level, including diagnostic approaches to assess those systems. The research groups have already explored some aspects of APEMFCs and this project will undertake the development of each aspect of the new technology in an integrated, multi-pronged approach whilst communicating their ongoing results to the members of a club of relevant industrial partners. The extensive opportunities for discipline hopping and international-level collaborations will be fully embraced. The overall aim is to develop membrane materials, catalysts and ionomers for APEMFCs and to construct and operate such fuel cells utilising platinum-free electrocatalysts. The proposed programme of work is adventurous: however, risks have been carefully assessed alongside suitable mitigation strategies (the high risk components promise high returns but have few dependencies). Success will lead to the U.K. pioneering a new class of clean energy conversion technology.