The Research About Water Loss Induced By Electro-osmotic In PEMFC And Modified Nafion^? Based Membrane To Enhance Water Containing Ability

Nowadays, the fossil energy become less and less, human are trying to find some substitution to replace it, the fuel cell is one the most promising candidates. The fuel cell has a compact structure, excellent power density and it’s environment friendly. It could be used in so many fields such as automotive industry, mobile power supply. The fuel cell has caught the market and researcher s’ attention. But,there are still some problems existing in the development of fuel cell technology. Among the problems, the water content’s influence on the membrane’s resistance which would control the cell’s performance is a tough. In my thesis, i have done a theoretical and experimental research on the water transfer in the PEMFC which decides the water containing in the membrane and its resistance. Then I made two kinds of modified membrane to enhance the membrane’s water containing ability, and achieved a higher cell performance for both modified membrane.In this thesis:Firstly, in chapter 2, I introduced all the theory knowledge about water transfer including background transfer theory, water transfer in the membrane and its influence on high frequency resistance(HFR).Based on the theory introduced in chapter 2, I explored the water transfer’s influence in the membrane in chapter 3, especially the eletroosmotic phenomenon’s effect. In this part, I considered different relative humidification and different membrane thickness. With the data achieved in experiment I built up the relationship among HFR,current density and water content. In addition, the membrane thickness’ impact on the HFR-current density is explored.In chapter 3 the Nafion based modified membrane containing Pt/C was explored. It was made by mechanic combination. The modified membrane shares similar physical property with the pure Nafion membrane. And the modified membrane’s cell performance is always higher than pure one in different relative humidification operation condition, when relative humidification is 65%, the performance improvement is most obvious.In chapter 5, modified membrane with [Pt(NH3)4](NO3)2 is made, and the effective Pt particle was achieved by a local reaction in the membrane in the cell. It has similar physical property with pure membrane, shows higher cell performance in different relative humidification than the pure one, but unfortunately the optimize operation relative humidification for cell performance maxmising was not found in my test.