Impact of In-Cell Water Management on the Endurance of Polymer Electrolyte Membrane Fuel Cells

Water management is critical for achieving optimal performance and endurance of polymer-electrolyte membrane fuel cells. The authors conducted endurance experiments of polymer-electrolyte membrane fuel cells using two water management schemes: a solid plate (SP) approach and a water-transport plate (WTP) approach. In addition to constant-current hold tests at 1 A/cm(2) to investigate the voltage decay, diagnostic tests, i.e., polarization curves, hydrogen crossover, cathode cyclic voltammetry, fluoride emission, and membrane tensile stress-strain, are also conducted to investigate the cell performance and membrane material state changes. At cell temperature 85 degrees C, anode RH 96% and cathode RH 75%, and no backpressure, constant current test results indicate significant differences of the degradation behavior between SP cells and WTP cells, suggesting different degradation rate controlling mechanisms. The representative WTP cell remains operational over 1500 hours of testing without failure. The representative SP cell fails catastrophically after 872 hours of testing. The WTP cell shows a much lower performance loss rate in terms of voltage decay and electrochemically-active surface area (ECSA) reduction at the cathode catalyst layers and less membrane mechanical decay than that of the SP cell. The improved performance and endurance is attributed to the better water management capability of the WTP cell. (C) 2014 The Electrochemical Society. All rights reserved.