Development of in-situ/ex-situ electrochemical measurement system for polymer electrolyte membrane fuel cells

通过发展现场和非现场电化学技术，构建了聚合物电解质膜燃料电池(PEMFC)的电化学测试系统。到目前为止，质子交换膜燃料电池的电池性能一直是通过单电池的I-V特性来评价的。本研究成功地建立了在电池运行环境下正确测量电池中使用的每种材料的基本方法。主要研究成果总结如下。首先，通过开发新型的多孔-微盘电极和多孔-微环电极，对粉末催化剂单独和催化剂/PEM层状结构的电化学性能进行了评估。第二，通过使用一组微电极，使得质子交换膜在厚度方向上的精确质子电导率成为可能。当将测量的电导率与用电流断续技术估算的电导率进行比较时，质子电导率的大小是一致的。第三，利用微盘电极的微定位特性，提出了一种新的酒精交叉评价方法。这使得在PEM上进行定量交叉分析成为可能。其次，通过光谱电化学测试，研究了芳香醇作为新的燃料候选的氧化还原机理。最后，采用交叉型微阵列电极，通过改变水与甲醇的混合比例，解决了聚合物电解质膜的离子电导率问题，这对直接甲醇燃料电池(DMFC)的运行具有重要意义。综上所述，通过设计现场/非现场电化学测试系统来评估PEMFC中的功能材料，极大地提高了对材料和电池系统的电化学研究。

Electrochemical measurement system for polymer electrolyte membrane fuel cells(PEMFCs) has been constructed by developing in-situ and ex-situ electrochemical techniques. Thus far, cell performances of PEMFCs have been evaluated by I-V characteristics of the single cell. The present study has succeeded to establish fundamental methods to measure each material used in the cell properly under the cell-operation environments. Main research results are summarized as follows. First, by developing novel porous-microdisc electrode and porous-microring electrode, electrochemical properties of powder catalyst alone and catalyst/PEM layered structure have been estimated. Second, precise proton conductivity of PEM in thickness direction has become available by employing a set of microelectrodes. When the measured conductivity was compared with that assessed by the current interruption technique, the magnitudes of proton conductivities were well agreed. Third, a new method for alcohol crossover evaluation at a PEM has been attained, utilizing a microdisc electrode based on its micro-positioning feature. This enabled a quantitative crossover analysis at the PEM. Next, redox mechanism of an aromatic alcohol as a new fuel candidate has been investigated according to a spectroelectrochemistry measurement. Finally, ionic conductivity of polymer electrolyte membrane has been resolved employing an interdigitated microarray electrode by changing a water : methanol mixture ratio, which is worthwhile for operating the direct methanol fuel cell(DMFC). In conclusion, by designing in-situ/ex-situ electrochemical measurement system to evaluate the functional materials in the PEMFC, electrochemical study for the materials and the cell systems have been greatly improved.