Effects Of Electrode Design On Performance And Transport Characteristics Of Alkaline Membrane Fuel Cell

With the increasing crisis of energy and environment,the requirement for energy conservation and emission reduction is growing.Vehicles,with internal combustion engine as the primary power source,become the crucial field for energy conservation and emission reduction.Therefore,electric vehicle(EV)and fuel cell vehicle(FCV)are attracting more and more attentions,because of the relatively low energy consumption,low emission and high efficiency.However,considering the special situation in China,the advantages of them are still in doubt.Therefore,a life cycle analysis of ICEV,EV and FCV,based on the situation of China,is carried out to compare the advantages and disadvantages of them in energy consumption,carbon emission and total efficiency.Results show that FCV,with hydrogen from natural gas reforming and from electrolysis of water powered by nuclear energy,are competitive.As one of the most suitable choices,alkaline anion exchange membrane fuel cell(AAEMFC)are currently gathering renewed interests,because of the faster electro-chemical kinetics and potential in using non-precious-metal catalysts.It is known that the electrode design,such as the micro porous layer(MPL)and the ionomer content in catalyst layer(CL),have great effects on the performance of AAEMFC.However,related researches,especially experimental studies,are rarely founded in literature.Therefore,experimental study for the effects of electrode design on AAEMFC performance is conducted,including whether inserting MPL and different ionomer content in CL.The influence of anode back pressure is also analyzed.Results show that the more the ionomer content in CL,the better the performance is;inserting MPL and increasing anode back pressure can also bring a promotion to the performance.To understand the effects of MPL,anode back pressure and membrane thickness from the perspective of water management,a 3D multiphase non-isothermal model is developed.Results show that inserting anode MPL,increasing anode back pressure and reducing membrane thickness can significantly improve the performance,and the improvement is enhanced with the increment of current density.Inserting cathode MPL has insignificant influence,for lack of water in cathode.With the pressurization of anode back pressure and reduction of membrane thickness,the mechanism of water transport from anode to cathode is changed from diffusion dominated to diffusion and hydraulic permeation dominated.The expected liquid saturation jump is also observed at the interface between two adjacent porous layers..