Water management is one of vital point to get enhanced durability as well as good performance of polymer electrolyte fuel cells (PEFCs). Especially the operation of cells at sub-zero temperatures is one of critical issues for the commercialization of PEFC vehicles.
The effects of sub-zero temperature operations were investigated by experimental approach. By changing the cell temperatures from -30 oC to 70 oC, the performance and the property changes of cells were observed with the number of temperature cycles. The cell performances as well as properties were compared with a reference cell which experienced the same number of temperature cycles between 30 oC to 70 oC. The post-analysis after the temperature cycles were conducted to check the changes in electro-chemical and physical properties. It was found that one of the main reasons of performance degradation after freeze/thaw cycles is in the physical destruction of electrode as well as its interface by the frozen water. Even small size of cracks on the electrode can cause the severe performance degradations at the sub-zero temperatures. To confirm the above mentioned deactivation reason, 3 kinds of gas diffusion layers (GDLs) such as felt, fiber and cloth type were investigated at the same freeze/thaw conditions. It’s revealed that the well contact between interfaces of materials can help enhancing the durability of PEFCs in the sub-zero condition.