Molecular Simulation On Proton Transfer In PEM Fuel Cell And Analysis Of Its Performance

PEM fuel cell is the most promising application as an automotive power, due to its hightransformation efficiency, clean and quiet performances, it has been a strategic product in theworld’s major industrial countries. However, researchers encounter great obstacle to popularizePEMFC because of its high cost. And one of the main methods to reduce its cost is to enhance itsoperating performance which is affect by increase the performance of the PEM fuel cell.Research on the performance experiment of the cathode reactants is helpful for performanceoptimization of PEM fuel cell. Meanwhile, in this paper, the proton transfer mechanisms areanalyzed by the molecular simulation based on the basic principle of molecular dynamics. Theresearch results are very helpful to understanding the proton transfer mechanism in protonexchange membrane and promoting the applications of PEM fuel cell.Based on a great number of corresponding references of both domestic and aboard, thispaper analyzes the former researches, introduces the history, characters, classification andapplication of PEM fuel cell, elaborate on the structure, working principle and the key parts ofPEM fuel cell and along with experiments and basic theory of simulation. And analysis theworking status of the theory and practical work status of PEM fuel cell base on theelectrochemical thermo dynamics and kinetics.In this paper, based the fuel cell test equipment, we built the fuel cell test systems. And thestructure, working principle and the operating steps of this test system are described. Influence ofoxygen concentration on performance of PEM fuel cell is studied, and the influence of gasflow,fuel cell temperature,humidification temperature to PEM fuel cell are analyzed.Experimental results show that with the increase of oxygen concentration, open potential of PEMfuel cell increases; the optimum flow rate of cathode reactant decreases with the increase ofoxygen concentration in PEM fuel cell; the ohm region enlarges and concentration over-potentialin U-I curve of PEM fuel cell decreases with the increase of oxygen concentration.In this paper, the proton transfer mechanisms are analyzed by the molecular simulationbased on the basic principle of molecular dynamics, especially the radial distribution function.Effects of operating parameters, such as water content and temperature, on the proton transfer inproton exchange membrane are analyzed. Results show that proton transfers in the Nafionpolymer by water bridges between two sulfonic groups of adjacent side chains. There are morewater bridges supporting proton transfer with the increase of water content in membrane. Theincrease of cell temperature speeds up the form and break of O-H bond, which promotes theproton transfer.