PEM fuel cell relative humidity (RH) and its effect on performance at high temperatures

• Published in: Electrochimica acta Vol. 53; no. 16; pp. 5315 - 5321
• Main Authors: Zhang, Jianlu, Tang, Yanghua, Song, Chaojie, Xia, Zetao, Li, Hui, Wang, Haijiang, Zhang, Jiujun
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 30.06.2008; Elsevier
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; High temperature PEM fuel cell; Mass transfer resistance; Membrane conductivity; O 2 reduction reaction kinetics; Relative humidity (RH); Relative humidity (RH); High temperature PEM fuel cell; O 2 reduction reaction kinetics; Mass transfer resistance; Membrane conductivity; Relative humidity; Power density; Oxygen; Electrical conductivity; Mass transfer; Operating conditions; Transport process; Chemical reduction; O2 reduction reaction kinetics; Kinetics; Performance; Electrochemical reaction; High-temperature fuel cells; Proton exchange membrane fuel cells; Transfer resistance; Electrical characteristic
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2008.02.074

The water balance inside a fuel cell was analysed and several equations were introduced as functions of fuel cell gas-stream inlet and outlet pressures, inlet relative humidities (RHs), temperature, pressure drops across flow channels, and reactant partial pressures. The effect of RH on PEM fuel cell performance was studied at elevated temperatures under ambient backpressure using Nafion ®-based MEAs. The results showed that fuel cell performance could be depressed significantly by decreasing RH from 100 to 25%. AC impedance and cyclic voltammetry techniques were employed to diagnose the RH effect on fuel cell reaction kinetics. Reducing RH can result in slower electrode kinetics, including electrode reaction and mass diffusion rates, and higher membrane resistance.