Experimental investigation of the effect of membrane water content on PEM fuel cell cold start

Abstract

In this study, the effect of membrane water content on proton exchange membrane (PEM) fuel cell cold start is investigated experimentally in detail. The cyclic voltammetry (CV) and high frequency resistance (HFR) are introduced to character electrochemical active surface area (ECSA) of the electrode and water content in the cell. Under normal condition, it is found that ECSA decreases with the decrement of membrane water content and a critical point of water content exists for the ECSA sharp decrement. Under cold start operation, low initial water content aggravates the voltage drop when the load is applied. The high initial water content leads to a rapid membrane water saturation, causing a short shutdown time, while the low initial water content may lead to a bad cold start performance. For the excessive low initial water content, the voltage reversal due to water electrolysis and carbon corrosion is also considered. Besides, the HFR is also recorded during cold start operation to estimate ice formation in the cell. It is indicated that a proper initial membrane water content after purge is significantly vital for PEM fuel cell cold start to achieve the balance of ECSA and ice storage capacity.