Polarization comparison and analysi

Polarization comparison and analysis are the most basic means of evaluating degradation. Fuel cell aging leads to performance degradation through variation in key parameters of the above formulas. For instance, membrane thinning or cracking increases hydrogen permeation and electronic short-circuiting, and also affects ionic conductivity. Pt catalyst degradation decreases the ECSA. The impact of the cathode catalyst is the dominant factor [74], because the oxygen reduction reaction (ORR) in the cathode is much slower than the hydrogen oxidation reaction (HOR) by at least six orders of magnitude [75]. Carbon corrosion decreases the electrochemical activity of the Pt catalyst. The carbon support forms the electronic conductive network of the CL, so its deterioration affects the ohmic resistance [76]. The state of the carbon and ionomer in the CL alsoimpacts the mass transfer, represented here by iL. Based on the empirical changing rules of the parameters in the aging process, Jouin et al. [29,60] presented a performance model encompassing an entire lifetime, which is helpful in guiding lifetime evaluation.Nowadays, under the background of unsatisfactory durability, prognostics and health management of the fuel cell have become even more important. Model-based [77,78], data-driven [79,80], and hybrid [76,81] methods have been reported in the literature for therobust prediction of remaining useful lifetime.