Mixed cation- and anion-exchange hybrid membranes for use in fuel cells, redox flow batteries and electrodialysis cells

该研究涉及混合聚合物电解质膜和膜电极组件（HyMEA）的开发，其包含不同的阳离子（质子）和阴离子（碱金属）交换相，相之间具有限定的界面或连接。将研究两种不同的方法：方法1（风险较低）将涉及使用市售的Nafion离聚物和质子交换膜沿着萨里先前开发的碱性离聚物配方和碱性阴离子交换膜制造HyMEA。第二种方法（涉及更基本探索的风险更高）将涉及从单一前体聚合物膜合成创新的混合膜，其中不同的阳离子和阴离子交换相通过化学连接分离。HyMEA将首先在燃料电池中进行评价，优选的实施方案中，其中酸性MEA与非酸性MEA的界面接触，并且其中不存在来自相之间的不期望的物理分离现象的干扰。相位于阳极，碱性相位于阴极。HyMEA的使用将允许使用低湿度氢气和空气气体供应，因为在运行的燃料电池中的水生成是在阳离子/阴离子交换结处，该阳离子/阴离子交换结远离电极本身（传统燃料电池中电极中的水生成会破坏反应物气体的供应，这导致质量传递导致的性能损失）;阳离子/阴离子交换结理想地位于HyMEA内部，以最大限度地保持聚合物电解质膜和膜的水合状态，从而实现最大的离子电导率。故意选择上文详述的合成方法以允许合成HyMEA和杂化膜，其中阳离子/阴离子交换结可以位于距阳极和阴极的受控（和变化的）距离处;因此可以确定每种方法的最佳水生成位置（例如，靠近阳极、靠近阴极、位于死点）。高pH阴极的存在也将允许使用非铂（非Pt）阴极（传统氢燃料电池的阴极，其中氧还原反应动力学缓慢，包含大部分Pt含量;阳极电动力学是上级的并且因此在阳极处可以使用显著更少的Pt）。最近，混合（双极）膜已应用于氧化还原液流电池和电渗析电池等技术：因此，该项目还将评估上述开发的混合膜的应用是否与这些技术有关。本影响评估的模型系统将是钒氧化还原液流电池和甲酸钠电渗析电池。主要目标：开发一系列HyMEA，最初用于需要非加湿气体供应和含有非铂族金属阴极的氢燃料电池。对在电渗析电池和氧化还原液流电池中使用开发的杂化膜进行初步可行性研究，以探索开发技术在非能源发电应用中的潜在影响（水技术和能源储存）。

The research involves the development of hybrid polymer electrolyte membranes and membrane electrode assemblies (HyMEA) that contain distinct cation(proton)- and anion(alkali)-exchange phases with a defined interface or junction between the phases. Two different approaches will be investigated: Approach 1 (lower risk) will involve the fabrication of HyMEAs using commercially available Nafion ionomers and proton-exchange membranes along with Surrey's previously developed alkaline ionomer formulations and alkaline anion-exchange membranes. The second approach (higher risk involving more fundamental explorations) will involve the synthesis of innovative hybrid membranes from a single precursor polymer film where the distinct cation- and anion-exchange phases are separated by a chemical junction/interface and where there are no interferences from undesirable physical separation phenomena between the phases.The HyMEAs will firstly be evaluated in fuel cells with a preferred embodiment where the acidic phase is located at the anode and the alkaline phase is located at the cathode. The use of HyMEAs will allow the use of low humidity hydrogen and air gas supplies as the water generation in the operating fuel cells is at the cation-/anion-exchange junction, which is located away from the electrodes themselves (water generation in the electrodes in traditional fuel cells can disrupt the supply of the reactant gases, which leads to mass transport derived performance losses); the cation-/anion-exchange junction is ideally located inside the HyMEA for maximum retention of the hydration state of the polymer electrolyte membranes and films for maximum ionic conductivity. The synthetic approaches detailed above were deliberately chosen to allow for HyMEAs and hybrid membranes to be synthesised where the cation-/anion-exchange junctions can be located at controlled (and varying) distances from the anode and cathodes; hence the optimum location of water generation (e.g. near to the anode, near to the cathode, located dead centre) can be determined for each approach. The presence of a high pH cathode will also allow for the use of non-platinum (non-Pt) cathodes (the cathodes of traditional hydrogen fuel cells, where the oxygen reduction reaction kinetics are sluggish, contain the bulk of the Pt content; the anode electrokinetics are superior and hence significantly less Pt can be used at the anodes).Recently, hybrid (bipolar) membranes have been applied to technologies such as redox flow batteries and electrodialysis cells: therefore, the project will also evaluate if the application of the hybrid membranes developed above is pertinent to these technologies. The model systems for this impact assessment will be a vanadium redox flow battery and a sodium formate electrodialysis cell.PRINCIPAL AIMS: To develop a range of HyMEAs that are initially targeted for use in hydrogen fuel cells that require non-humidified gas supplies and that contain non-platinum-group-metal cathodes.ENSUING PROJECT AIMS: An initial feasibility study on the use of the developed hybrid membranes in electrodialysis cells and redox flow batteries to explore the potential impact of the developing technologies in non-energy generation applications (water technologies and energy storage).