Characterization of Proton Exchange Membrane Fuel Cell Operating in Electrochemical Hydrogen Compression Mode

This study examines the performance of a proton exchange membrane fuel cell operated in electrochemical hydrogen compression (EHC) mode, focusing on the effects of temperature, relative humidity (RH), and pressure on water management and efficiency. Two humidification strategies were investigated: (i) a dry cathode with humidified anode hydrogen and (ii) a flooded cathode with controlled anode humidification. Experiments were conducted at different temperatures (from 35 to 70 °C), RH levels (from 0 to 100%), and compression ratios of 1 and 2, using polarization curves, electrochemical impedance spectroscopy, and linear sweep voltammetry (LSV). In the dry cathode configuration, optimal performance occurred at 70 °C with fully humidified anode gas, achieving current densities above 2 A cm−2 at voltages below 0.3 V. Partial humidification caused instability due to membrane dehydration. In the flooded cathode, high cathode pressure increased mass transport resistance, while excessive inlet humidification promoted flooding and consequently reduced the efficiency. LSV results highlighted the trade-off between proton conductivity and hydrogen back diffusion, particularly for thin membranes used in this study. The findings demonstrate that precise water balance is essential for stable and efficient EHC operation and provide guidelines for optimizing compression performance, supporting the development of high-efficiency and low-maintenance hydrogen compression systems for stationary and mobile applications.