Simultaneous measurements of transient water concentration and voltage response under low-humidity and load-change operation using fiber-optic laser spectroscopy

Effective mitigation of membrane dehydration and voltage undershoot in polymer electrolyte fuel cells (PEFCs) under low humidity and load fluctuation requires a detailed understanding of internal water transport. This study employs fiber-optic tunable diode laser absorption spectroscopy (TDLAS) to simultaneously measure the anode-side water vapor concentration and cell voltage response in a PEFC under such operating conditions. The investigation also evaluates how inlet gas humidification, applied current range, and electrode compression affect water dynamics across the membrane and related voltage behaviors. Findings reveal a close link between voltage transients and water concentration within the anode. A rapid increase in current density causes momentary water loss and voltage drop due to electro-osmotic drag and membrane drying. Enhancing humidification and increasing compression were found to improve water retention, suppress voltage drop, and promote stable operation under these demanding conditions.