Modeling And Life Prediction Of Fuel Cell Performance Degradation Under Operating Conditions

Proton exchange membrane fuel cell is considered as an ideal power source for vehicle power plant due to its advantages of moderate working temperature,high energy efficiency and portability.Compared with the traditional internal combustion engine,the durability of fuel cell is one of the important factors that restrict the commercialization of PEMFC.Therefore,more and more researches focus on the service life of PEMFC.As a key strategy for improving the durability of fuel cells,prediction and health management（PHM）play a crucial role in improving their life span,the output voltage and durability of the fuel cell can be predicted effectively by the way of simulation modeling.This method can greatly reduce the test cycle and cost of fuel cell durability test.In this paper,a model of fuel cell output voltage is established based on the model-driven method and the data-driven method.According to the durability of fuel cell under different working conditions,the attenuation reason is further analyzed by using the model.In the durability test of this paper,square wave scan test,stress acceleration test,isolation test and NEDC test of three section membrane electrode are carried out respectively,in the course of single-section membrane electrode testing,only the steady-state polarization performance testing is carried out,the current of each data point is maintained for 3 minutes,and the changes of all parameters are recorded under NEDC working condition,and data points are collected every second,the total test time of NEDC is 900h.In this paper,the causes of four polarization losses of PEMFC were analyzed,and a model for predicting the lifetime of PEMFC was established.Based on the durability test data,two fuel cell models under steady-state and dynamic conditions were optimized.The results show that the fuel cell model established in this paper can accurately predict the fuel cell output voltage.The mean square error（MSE）of the dynamic model is 3.62×10^-4,and that of the steady model is 1.2×10^-6.By using the established fuel cell voltage model,this paper analyzes the performance degradation of fuel cell during square wave scan test and NEDC test.It is found that the increase of Tafel intercept（a）and Tafel slope（b）leads to the increase of leakage polarization and activation polarization in the process of square wave’s scanning experiment.All other parameters showed significant increases.In the course of NEDC test,except for the small change of each parameter,the limiting diffusion current density of fuel cell decreases sharply at 300h and 800h.This decline is not consistent with the decay law and can be attributed to the mechanical damage to the fuel cell components caused by the operation of the test process.After analysis,the damage location is determined as gas diffusion layer.