Fuel and oxidant must be adequately

Fuel and oxidant must be adequately supplied to ensure normal electrochemical operation of the PEM fuel cell, or abnormal reaction will happen to degrade the components. In the load-up process, the reactant supply lags behind the current increase . Thus, faster load-up results in more severe gas starvation. Moreover, the distribution and supply of reactants in a fuel cell are inherently uneven, especially in fuel cells with a large active area. For example, there are inherent differences between different locations in a fuel cell stack [35,235], between the gas inlet and the outlet of a fuel cell , and even between the rib region and the channel region [34]. Differences may be magnified in the load-up process, thus causing various degrees of gas starvation. The air starvation and the fuel starvation accelerate fuel cell aging in disparate ways.