Effect of Bulk and Surface Treatments on the Surface Ionic Activity of Nafion Membranes
Effect of Bulk and Surface Treatments on the Surface Ionic Activity of Nafion Membranes
复制标题
本体和表面处理对 Nafion 膜表面离子活性的影响
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Wensheng He
中科院分区：
文献类型：
--
作者：
T. Nguyen;M. Nguyen;K. Nordheden;Wensheng He
质子交换膜质子交换膜燃料电池因其功率密度和效率高、设计和操作简单、以氢为燃料零排放等优点而被公认为是一种强有力的替代能源转换系统和动力源。然而，有几个方面需要优化，以进一步提高这种燃料电池的功率输出，从而使其与传统能源转换设备相比更具竞争力。我们感兴趣的一个领域是降低Nafion膜表面的离子电阻。与其他聚合物一样，Nafion膜的表面能很低，导致附着力较差。根据Mittal和Pizzi的说法，1聚合物对聚合物的粘合更多地是机械互锁的结果，而不是界面相互作用的结果，而聚合物对金属的粘合主要是通过界面相互作用实现的。在质子交换膜燃料电池中，发电组件膜电极组件MEA的制备主要有两种方法。在一种方法中，将由Nafion离子聚合物相和碳载体上的固体铂组成的催化层热压到膜的两侧以形成三层MEA。使用的任何多孔碳扩散层都被放置在与催化层物理接触的位置。在另一种方法中，首先将催化层施加在多孔炭支撑层上，然后热压到膜上，形成一体化的五层MEA。无论采用何种方法编制多边环境协定，多边环境协定中都存在这两种类型的接口。聚合物-金属界面存在于催化层中的离子聚合物相与固体催化相之间，聚合物-聚合物界面存在于催化层中的离子聚合物相与聚合物电解质膜之间。膜表面SO3H+基团在聚合物-催化剂界面上的表面离子活性面积、浓度或数目影响电化学反应速率和质子和水进出催化剂表面的传输速率。聚合物电解质膜与催化层中离子聚合物相界面的表面离子活度影响着质子和水在该界面上的传输速率。有关膜表面离子活性对聚合物-催化剂界面的影响的信息可在参考文献中找到。2.在本研究中，我们考察了不同的膜体积和表面处理工艺对膜的表面离子活性的影响，以及膜表面离子活性对质子交换膜燃料电池膜电极性能的影响。
The proton exchange membrane PEM fuel cell has been recognized as a strong alternate energy conversion system and power source because of its high power density and efficiency, simplicity in design and operation, and zero emission if hydrogen is used as fuel. However, there are several aspects that need to be optimized to further increase the power output of this fuel cell, thus making it more competitive with conventional energy conversion devices. One area of interest to us is the reduction of the ionic resistance at the surface of the Nafion membrane. Nafion membrane, like other polymers, has a low surface energy, which causes poor adhesion. According to Mittal and Pizzi, 1 polymer-to-polymer adhesion is more a result of mechanical interlocking than interfacial interaction, whereas polymer-to-metal adhesion is achieved mostly by interfacial interaction. In a PEM fuel cell, the power-generating component called the membrane-and-electrode assembly MEA is prepared, mainly, by two methods. In one method, the catalyst layers composing of a Nafion ionic polymer phase and solid Pt on carbon support are hot pressed onto each side of the membrane to form a three-layer MEA. Any porous carbon diffusion layers used are placed in physical contact with the catalyst layers. In the other method, the catalyst layers are first applied on the porous carbon support layers and then hot pressed onto the membrane to form an integrated five-layer MEA. Regardless of the methods used to prepare the MEAs, both types of interfaces exist in the MEAs. The polymer-to-metal interface exists between the ionic polymer phase and the solid catalyst phase in the catalyst layers, and the polymer-to-polymer interface exists between the ionic polymer phase in the catalyst layers and the polymer electrolyte membrane. The surface ionic activity area concentration or number of the SO3 H + group on the surface of the membrane at the polymer-tocatalyst interface affects both the electrochemical reaction rates and the transport rates of the protons and water to and from the catalyst surface. The surface ionic activity at the interface of the polymer electrolyte membrane and ionic polymer phase in the catalyst layer affects the transport rates of the protons and water across this interface. Information on the effect of the membrane surface ionic activity on the polymer-to-catalyst interface can be found in Ref. 2. In this study, we investigated the effects of various membrane bulk and surface treatment processes on the surface ionic activity of the membrane and the subsequent effects of the membrane surface ionic activity at the polymer-to-polymer interface between the ionic polymer phase in the catalyst layer and the polymer electrolyte membrane on the performance of the MEA in a PEM fuel cell.