On the influence of methanol addition on the performances of PEM fuel cells operated at subzero temperatures

SAXS Investigation of the Effect of Freeze/Thaw Cycles on the Nanostructure of Nafion® Membranes

“…A commercial 50-μm-thick Nafion ® 212 membrane (DuPont, Wilmington, DE, USA) was chosen for this study. All membrane samples were converted to the H + form by soaking in a 10 wt.% aqueous solution of HNO 3 (Uralchem, Moscow, Russia) at 90 °C for 1 h, followed by double washing with deionized (DI) water under the same conditions [ 17 ].…”

“…A series of F/T cycles in the temperature range from −40 to 20 °C were used to investigate the effect of thermal cycling on the nanostructure of membrane samples fully swollen in water. The F/T cycling procedure is described in detail in [ 17 ]. To evaluate the effect of methanol addition, the membrane was soaked in a water-methanol (Metafrax, Gubakha, Russia) mixture (20 vol.% of methanol) before the F/T cycling.…”

“…However, it requires additional equipment, complicates the shutdown/start-up strategy, and significantly increases the time to start up PEMFC and achieve operational characteristics. More promising methods are the use of alcohol mixtures instead of water for the membrane swelling [ 15 , 16 , 17 , 18 ] or the use of hydrophilic additives involved in the binding of free water [ 19 , 20 , 21 ]. These approaches make it possible to significantly increase the service life of the MEA components under conditions of subzero temperatures, and to start up and shutdown PEMFCs without additional stages and equipment.…”

“…As has been reported before [ 22 , 23 ], methanol molecules can integrate into the polymer backbone, leading to deterioration of the membrane strength and methanol crossover. A methanol content in solution of 10–20 vol.% was proposed as the optimal one [ 17 ]. At lower methanol concentrations, the MEA stability with regard to freezing is insufficient while at higher concentrations, the Nafion ® membrane dissolves, its strength decreases, and the ionic resistivity tends to increase.…”

Carbon-Supported Pt-SnO2 Catalysts for Oxygen Reduction Reaction over a Wide Temperature Range: Rotating Disk Electrode Study

“…First, drying of the ionexchange polymer is observed at high temperatures and low humidity, which leads to a deterioration in proton conductivity both in the catalytic layer ionomer and in the membrane [3][4][5][6]. Second, at negative temperatures, ice crystals are formed inside MEA components, and destruction of the catalytic layers and membrane occurs during freezethaw cycles [7][8][9][10][11][12][13]. These problems can be solved by applying additives with high water retention ability, such as tin dioxide [14][15][16][17][18].…”