Research On The Relationship Between Fuel Cell Performance And MEA Parameters And Lifetime Prediction Based On The Attenuation Law

Membrane electrode assembly(MEA)parameters influence the performance of power generation and service lifetime of proton exchange membrane fuel cells(PEMFCs).This paper concentrated on exploring the relationship between MEA parameters and fuel cell performance and predicting lifetime based on the attenuation law.A theoretical model between MEA parameters and performance was constructed.Then the fuel cells’attenuation characteristics were found.Finally,lifetime prediction methods were presented and validated.The semi-empirical formula of MEA parameters and fuel cell performance was established.It was found that the exchange current density could be avoided by using the hydrogen crossover and initial open circuit voltage.Taking into account electrochemically active surface area,activation losses showed a significant attenuation trend with fuel cells’aging successfully.In addition,the formula was validated on an aging 34 cm~2 fuel cell.Finally,it was used to attain activation impedance,concentration impedance and limiting current,which was helpful to obtain the average gas diffusion coefficient effecting internal microscopic conditions of gas diffusion layer.The attenuation characters were found during fuel cells’aging.If the overall current of polarization curves in different states were changed to the ratio of the overall current and a current at a special voltage,it was found that the similar polarization curves,which were formed by this ratio and its corresponding voltage,were uniformly coincident with each other in different aging phases.This phenomenon was defined as the similarity of volt-ampere characteristics.What’s more,it was suitable for other types of fuel cells.Then the consistency law of voltage attenuation and voltage consistency characteristics at maximum power were proposed and validated.It was found that fuel cells complied the above attenuation characteristics under different aging conditions or usage modes,indicating that characteristic laws might be inherent properties of fuel cells,which were irrelevant with external conditions.Based on the attenuation law,prediction methods were established and verified.Firstly,with the circuit theorem,a first-order response’s life prediction model for voltage attenuation was proposed,and the fuel cell’s ultimate life was defined and obtained.Then,according to the first-order kinetic reaction mechanism in chemistry,the attenuation of current under constant voltage was applied to the field of fuel cell aging prediction.And the time constant was used to show fuel cell aging entered a sharp decline of performance.In addition,combining with the volt-ampere characteristic’s similarity law and current decay method,a voltage attenuation law under certain conditions were achieved to predict lifetime.Finally,based on the voltage and current attenuation laws,another method for overall lifetime prediction was proposed.The research achievements develop the theory of the relationship between MEA parameters and fuel cell performance and provide basic theoretical support for extending fuel cells’service life;The aging characteristics for fuel cells are proposed,which provides a significant reference value for researches of other types of fuel cell.Various life prediction methods are developed,which is of significance for evaluating the aging status,remaining life and ultimate life of fuel cells.