The water management system does no

The water management system does not only affect PEMFC performance but also its durability. A number of degradation factors such as the loss of active surface area of the catalyst, ionomer dissolution, corrosion, contamination, and morphological damages of MEA and GDL were identified which are influenced by water formation, retention, accumulation and transport mechanisms within the cell. It is difficult to determine accurately the impact of each of these water mechanisms on the deterioration rate of the cell as it varies depending on the design and the operating conditions of the cell. For example, the effect of water retention and accumulation becomes more severe when the cell operates at subfreezing temperatures. The volume expansion of liquid water due to the ice formation causes morphological damages to different parts of the cell which can accelerate the degradation process. Furthermore, theeffect of these water mechanisms on cell durability can be classified into two main categories: ageing and catastrophic. With ageing, durability and performance behaviour of the cell tend to decline steadily over time whereas in the case of catastrophic ones the cell fails instantly.