Membranes for PEM fuel cells

The progress of fuel cell technology since middle of 80s has converted the fuel cell concepts to a widely accepted power units for 21st century. The central component of the technology is the membrane. The membranes are designed to high-power, high lifetime, and high reliability at application’s conditions. Depending on the application, the membranes are distinguished mostly by its thickness. Special types of fuel cells are powered by electrochemical conversion of low alcohols. The thinnest membranes 10-15 µm are tailored to use in fuel cell vehicles of power class from 50kW up to 300kW such as passenger cars, light-duty trucks or buses; this class includes also the scalable modules for trains.

The thickness of membranes for projected propulsion of heavy-duty trucks and in marine sector is approaching 20-30 µm for its ultimate lifetime meeting the target of the power class of 500 kW up to multi-MW system.

The membranes in thickness 60-100 µm are designed for Hydrogen-Oxygen operation allowing pressure operation and very high reliability. The membranes F-14100 and F-1850 are blend membranes for use in fuel cell, where direct alcohol conversion is aimed on. The membranes feature low swelling and low fuel cross-over. The overview of the membranes is summarized in Table 1 and Table 2.

Typical properties of FC membranes for transport applications

Membrane FS-710-RFS FS-715-RFS FS-930-RFS
SSC-Polymer EW 720 720 870
Application Automotive Automotive, bus, light truck Heavy truck, marine
Reinforcement Microporous Microporous Microporous
Chemical stabilization yes yes yes
Thickness / µm 10 15 30
Resistance @ 80 °C, 80% rh / mOhm.cm2 (1) 7 11 27
H2 cross-over at BOL / (2) 1,8 1,2 0,8

(1) Measured as EIS in four-point conductivity cell measurement
(2) Measured as LSV in FC fixture at 80 °C and atm. pressure

Properties of FC membranes for H2-O2 and for DMFC and related applications

Membrane FS-960-RFS FS-990-PKS F-1850 F-14100
Polymer EW SSC-870 SSC-870 LSC-blend 1800 LSC-blend 1400
Application(1) H2-O2 H2-O2 DMFC DMFC
Reinforcement Microporous PEEK woven web none none
Radical stabilization yes yes none none
Thickness / µm 60 90 50 100
Resistance / mOhm.cm2(2) 65 95 110 150

(1) DAFC = direct alcohol fuel cells (methanol, ethanol, propanol)
(2) Measured as EIS in four-point conductivity cell measurement. Resistance of FS-membranes measured at 80 °C and 100 % rh, resistance of F-membranes measured at 60 °C in DI water.

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