Characteristics of the PEMFC Repetitively Brought to Temperatures below 0°C

Abstract

Freezing of water in a polymer electrolyte membrane fuel cell ͑PEMFC͒ may cause severe problems in driving a fuel cell vehicle during the winter time. Characteristics of PEMFC which suffered low temperatures below zero celsius were examined with thermal cycles during which the temperature of the environment chamber was cycled from 80 to Ϫ10°C. With the thermal cycles, the cell performance was degraded due to the phase transformation and volume changes of water. Effects of freezing of water in a PEMFC on the electrode structure and polarization resistance were examined by Brunauer, Emmett, Teller analysis, cyclic voltammetry, and ac impedance spectroscopy.

A review of polymer electrolyte membrane fuel cell durability test protocols

“…Subjecting a PEMFC to subfreezing temperatures has been reported to cause significant drops in the cathode electrochemical surface area (ECSA), which was attributed to ice formation in the CLs that resulted in increased porosity and ultimate delamination of the CL from the membrane [53]. The effect of freeze/thaw thermal cycles on the properties of MEA components (CL, GDL, and membrane) has been extensively studied but mostly through ex situ investigations, and the results are sometimes conflicting.…”

“…The effect of freeze/thaw thermal cycles on the properties of MEA components (CL, GDL, and membrane) has been extensively studied but mostly through ex situ investigations, and the results are sometimes conflicting. Generally, freeze-thaw cycling will change the water content/state in the CLs [53], the air permeability of the GDL [31], and the conductivity of the membrane [54,55]. Detailed characterization of the durability of MEA components under fuel cell operating conditions during freeze/thaw cycles apparently needs to be better evaluated [45].…”

Cold start characteristics and freezing mechanism dependence on start-up temperature in a polymer electrolyte membrane fuel cell

“…Cyclic voltammetry studies on the degradation of the electrochemically active Pt area of the cathode catalyst layer due to the ice formation were conducted for a cell containing a membrane with high water content after freezing/thawing cycling [1,2] and during and post-subzero start-up of a PEFC [3]. Here, together with the permanent degradation caused by structural alterations of the cathode catalyst layer [1][2][3], a temporary deterioration of the cell performance was reported after start-up from subzero temperatures and the warm-up to 25 °C with all ice in the catalyst layer melted [3]. Tajiri et al proposed a strict gas purge process before cold start operation, and estimated the ice distribution in the cathode catalyst layer at the end of cold starting at -30 °C at low and high current densities [5].…”

Isothermal Ice Crystallization Kinetics in the Gas-Diffusion Layer of a Proton-Exchange-Membrane Fuel Cell

“…To date, experimental studies of PEMFC coldstart primarily focus on characterizing overall low-temperature cell performance including: degradation after freeze-thaw cycles 1 , effects of cell material properties [2][3][4][5][6] , and in-situ visualization of ice formation. 7,8 Numerous studies show that the cell electrical potential decays rapidly at low temperatures and/or at high current densities due to ice formation at the reactive area of the cathode.…”

“…7,8 Numerous studies show that the cell electrical potential decays rapidly at low temperatures and/or at high current densities due to ice formation at the reactive area of the cathode. [1][2][3][4][5][6] Few studies, however, focus on understanding the mechanism of ice crystallization. In two cases, the formation of liquid water and ice within the cathode was visualized using infrared and visible imaging.…”