| Summary: | 博士 === 國立中興大學 === 精密工程學系所 === 107 === This research focused on the preparation of non-platinum electrodes applied for anion exchange membrane fuel cells (AEMFCs). Specifically, two attempts including the development of silver nanoparticles supported on functionalized carbon particles (Ag/C) used as the cathode catalyst in AEMFCs and the study of the effects of PTFE content in gas diffusion substrate, microporous layer, cell temperature and inlet gas humidification on AEMFC performance were carried out. The characterization results show that Ag/C catalyst was successfully synthesized by wet impregnation method. For AEMFC performance evaluation, the experimental results showed that the peak power densities of the single AEMFC using Ag/C were only 3.5% lower than that using commercial Pt/C which was consistent with the cyclic voltammetry (CV) and linear sweep voltammetry (LSV) measurements. Therefore, the Ag/C can be used as the cathode catalyst to substitute the commercial Pt/C as the strategic cost reduction, so that a commercialized alkaline anion exchange membrane fuel cell can be realized.
Moreover, the gas diffusion substrate (GDS) treated with polytetrafluoroethylene (PTFE) can offer not only an appropriate hydrophobic level but also robust supporting for the microporous layer and catalyst layer. Thereby, well water management and catalyst usage in the cell can be obtained during the cell operation. The testing results showed that the best cell performance was achieved by employing the GDS with 30 wt.% PTFE content and MPL at both anode and cathode sides of a single AEMFC. Although PTFE treatment in the GDS is beneficial for AEMFC performance, excessive PTFE embedment in the GDS will lead to an adverse effect due to most of the pores on the GDS surface blocked by excessive PTFE particles, causing a severe hindrance of transport of reactant gas and water. In addition, it is found that the AEMFC performance was strongly affected by the cell operating temperature and highly sensitive to humidification at both anode and cathode inlet gases. Besides, back diffusion could partly support the water demand at the cathode once the water concentration gradient between the anode and cathode is formed. These results suggest that the water management in AEMFCs plays a critical role in achieving a desirable cell performance.
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