Ultrasonic-assisted Fabrication Of Hydrophobic Carbon Paper And Its Application In PEMFC

Energy and environmental issues have become a key issue that cannot be ignored in human development.With the depletion of fossil energy and the aggravation of environmental pollution,research in the field of new energy has gradually attracted the attention of all countries.Proton exchange membrane fuel cell(PEMFC),as a clean and efficient environmental protection power supply,has a wide application prospect in new energy vehicles,power plants,aerospace and other fields.Carbon paper,as an important part of PEMFC,usually needs to be hydrophobic treated with polytetrafluoroethylene(PTFE).The hydrophobic treatment method has an important influence on the performance of PEMFC.In this paper,ultrasonic-assisted impregnation method is used to fabricate hydrophobic carbon paper,which is compared with the traditional impregnation method.The effect of hydrophobic carbon paper fabricated by this method on the performance of PEMFC is also studied by simulation and experiment.The main contents are as follows:(1)Fabrication of hydrophobic carbon paper under different conditions by ultrasonic-assisted impregnation method and traditional impregnation method respectively.The results show that compared with the traditional impregnation method,the ultrasonic-assisted impregnation method can produce hydrophobic carbon paper with higher PTFE content under shorter time and lower PTFE emulsion concentration,and the content of PTFE in hydrophobic carbon paper increases with the increase of ultrasonic power.When ultrasonic power is too big,the edge of hydrophobic carbon paper will crystallize seriously.(2)The hydrophobic carbon paper with specific PTFE content is fabricated by ultrasonic-assisted impregnation method and traditional impregnation method.The results showes that when the PTFE content in carbon paper is the same,the porosity,permeability and electrical conductivity of hydrophobic carbon paper fabricated by ultrasonic-assisted impregnation method are higher than those fabricated by traditional impregnation method,and the distribution of PTFE in hydrophobic carbon paper fabricated by ultrasonic assisted impregnation is more uniform.(3)The ideal two-dimensional model of hydrophobic carbon paper fabricated by different methods is established by FLUENT.The evolution and transmission of liquid water in hydrophobic carbon paper are studied.It is found that due to the influence of capillary force,liquid water will preferentially enter the hydrophilic channel.A large amount of liquid water is accumulated in the middle of hydrophobic carbon paper fabricated by traditional impregnation method,and its total liquid water saturation is greater than that of hydrophobic carbon paper fabricated by ultrasonic-assisted impregnation method.(4)A two-phase flow mathematical model of PEMFC is established to study the effect of hydrophobic carbon paper fabricated by ultrasonic-assisted impregnation on the performance of PEMFC.The results show that,for the hydrophobic carbon paper fabricated by ultrasonic-assisted impregnation method,the PTFE distribution is more uniform,the liquid water in the carbon paper is easier to be discharged,and its porosity is larger,which is conducive to the transmission of reaction gas,and the oxygen concentration difference between the flow channel and the catalyst layer is smaller.Therefore,the hydrophobic carbon paper fabricated by ultrasonic-assisted impregnation method can make concentration polarization of PEMFC smaller and the performance of PEMFC improved.(5)The zoned PEMFC is designed.The effect of hydrophobic carbon paper fabricated by ultrasonic-assisted impregnation method on the performance of PEMFC is studied by experiment.The results show that compared with the hydrophobic carbon paper fabricated by traditional impregnation method,the hydrophobic carbon paper fabricated by ultrasonic-assisted impregnation method can make the performance of PEMFC better and more stable,the current density distribution more uniform,and the performance of PEMFC is the best when the content of PTFE is 10%.