Development and performance diagnosis of a high power air-cooled PEMFC stack

•An air-cooled PEMFC stack with the peak power of 2.55 kW is developed and tested.•Stack resistance is studied at various stack and dew point temperatures.•Synchronous EIS analysis of all cells throughout the stack was studied.•Improper combinations of stack temperature and humidity lead to non-uniform EIS.•The central cells of the stack are more sensitive to the temperature and humidity.

Although an air-cooled proton exchange membrane fuel cell stack is usually designed below 1 kW because of the cooling capacity limit, development of a high power air-cooled stack is still necessary. In this work, an air-cooled proton exchange membrane fuel cell stack with the maximum power of 2.55 kW is successfully developed. The efficiency of the fuel cell stack is 43.1% at the maximum output power. The maximum heat flux through the cooling channel of the stack is estimated to be 2.61 × 103 W m−2 and the average rate of heat transfer through an individual cooling channel is 1.5 W. The performance tests at different stoichiometric ratios and the electrochemical impedance spectroscopy measurement at various stack temperatures and dew point temperatures were carried out. A synchronous measurement of the electrochemical impedance spectroscopy (EIS) of all 40 cells was also carried out to understand the EIS distribution throughout the stack. The experimental results show that an appropriate combination of operational parameters can avoid a high stack resistance and a non-uniform resistance distribution throughout the stack.