Alkaline Polymer Electrolyte Fuel Cells

第一个可行的大规模燃料电池系统是由弗朗西斯培根开发的液体电解质碱性燃料电池。直到最近，整个航天飞机舰队都是由这种燃料电池供电的。这些燃料电池的主要困难在于液体电解质，其难以固定并且由于形成低溶解度碳酸盐物质而存在问题。随后的材料开发导致了质子交换膜（PEM，例如Nafion）的引入和众所周知的PEMFC的开发。成本是PEMFC商业化的主要抑制因素，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，负载量仍然很高）;（2）PEM;和（3）双极板材料（很少有廉价材料可以与超酸Nafion接触）。由于电渗阻力，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）表现出降低的性能，由于迁移的甲醇到阴极（电压损失和浪费的燃料）。最近的进展，在材料科学和化学允许生产的膜材料和离聚物，这将允许开发的碱等效的PEM。这些碱性阴离子交换膜（AAEM）的应用有望在燃料电池的可行性上实现飞跃。申请人团队包含开发这项创新技术的世界领导者。这种燃料电池（传导OH-阴离子而不是质子）提供了许多显著的优点：（1）燃料电池反应的催化在碱性条件下比在酸性条件下更快-实际上非铂催化剂在这种环境中表现非常有利，例如Ag用于氧还原。(2)更多的材料在碱性环境中比在酸性环境中显示出耐腐蚀性。这增加了可以使用的材料的数量和化学性质（包括便宜的、容易冲压的和薄的金属双极板材料）。(3)非氟化离聚物是可行的，并承诺显着降低膜成本。(4)OH-阴离子传导电解质内的水和离子传输是有利的，电渗拖曳将水从阴极传输走（防止阴极上的溢流，这是PEMFC和DMFC的主要问题）。这一过程也缓解了DMFCs中的“交叉”问题。该研究计划涉及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。这项研究将由一个由世界领先的材料科学家、化学家和工程师组成的财团进行，该财团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。该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栈水平，包括评估这些系统的诊断方法。研究小组已经探索了APEMFCs的某些方面，该项目将以综合，多管齐下的方法开发新技术的各个方面，同时将其持续的结果传达给相关工业合作伙伴俱乐部的成员。学科跳跃和国际级合作的广泛机会将得到充分的接受。总体目标是开发用于APEMFC的膜材料、催化剂和离聚物，并利用无铂电催化剂构建和操作此类燃料电池。拟议的工作方案是冒险的：然而，风险已经过仔细评估，同时采取了适当的缓解战略（高风险部分承诺高回报，但依赖性很小）。成功将导致英国。开创了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.