Simulation And Design Of Cathode Catalyst Layer In Proton Exchange Membrane Fuel Cells

Fuel cell is an electrochemcial energy conversion device with high efficiency and low emissions.However,its large-scale commercialization is limited by high cost,which mainly comes from expensive Pt-based precious metal catalysts.In order to reduce the cost of fuel cell,Fe/N/C non-noble metal catalyst has received wide attention.However,the high thickness the cathode catalyst layer made by Fe/N/C catalysts results in a serious problem in mass transfer.Thus,improving mass transfer of Fe/N/C cathode is a key issues to boost the performance of Fe/N/C-based fuel cells.Because of limited experimental methods,it is difficult to get accurate data of mass transfter from the fuel cell.On basis of well-developed theories,a reasonable mathematical model can be established to get more data in fuel cells.So the simulation is playing a more and more important role in the research of fuel cells.In this study,a fuel cell cathode catalyst layer model which contains gas diffusion layer,cathode catalyst layer and proton exchange membrane was constructed.The corresponding model equation was solved by COMSOL Multiphysics.The mass transfer law and electrochemical properties in the cathode catalyst layer were obtained from the results.An ordered catalyst layer was designed to improve the performance of fuel cell.Some significant results were achieved as follows:(1)A two-dimensional,two-phase multicomponent mathematical model which included the fluid flow,gas diffusion in porous media,water transfer in the catalyst layer and electrochemical reaction,was set to describe the proton exchange membrane fuel cell(PEMFC).(2)Using COMSOL Multiphysics software to solve the mass transfer equations and electrochemical kinetics equation,we could get electrochemical behavior of PEMFC and the distribution in the cathode catalyst layer of liquid water saturation and oxygen concentration.The effects of current density,gas pressure,cathode catalyst layer porosity on liquid water saturation and oxygen transfer were discussed.(3)A catalyst layer structure with ordered channels was designed.By solving the two-dimensional,two-phase,multicomponent mathematical axisymmetric model,we found that the gas and liquid water transfer resistance was reduced in the cathode catalyst layer,and the whole oxygen concentrations in the catalytic layer was increased,and the flooding in the cathode catalyst layer was relieved.(4)Through optimizing the width of ordered channels,we found the cathode catalyst layer with 20 ?m-width channels has the best performance.This study provides a feasible solution for the problem of mass transfer in PEMFC catalyst layer.