Performance losses at H2/O2 alkaline membrane fuel cell

•Significant potential loss in AMFC caused by low ionic conductivity of membrane and catalyst layer•Severe performance loss is also caused by low water concentration at catalyst surface.•Operation at high temperature essential to increase the water concentration in humidified oxidant

H2/O2 alkaline membrane fuel cell (AMFC) is evaluated by polarization curves and conductivity measurements to determine the performance limiting factors. The analysis of IR corrected polarization curves shows that at medium to high current region significant potential loss in AMFC is caused by low ionic conductivity of membrane and catalyst layer, and limitations from mass transport of water. In low to medium current region the severe performance loss is caused by low water concentration at catalyst surface due to insufficient water concentration in the fully humidified oxidant at ≤ 60 °C.