Gas Diffusion Layers (GDL)

AvCarb’s Gas Diffusion Systems incorporate a hydrophobically treated AvCarb GDL, and a surface coated microporous layer, optimized for specific fuel cell construction and operating requirements. The designs are based upon 25 years of collaboration with world leading fuel cell manufacturers and span the full range of today’s operating environments. AvCarb’s best in class quality and manufacturing flexibility provides the best customer value minimizing manufacturing scrap and costly re-builds due to low performing cells and providing best in class durability with GDL performance shown for over 38,000 hours of continuous operation in some systems
TYPICAL PROPERTY AvCarb® EP40 AvCarb® P75 AvCarb® EP55 AvCarb® EP25
Nominal Thickness (μm) (@ 5.0 N/cm2) 184 232 262 140
Nominal Basis Weight (g/m2) 36 71 51 27
Break Strength (N/m) Machine direction 1500 2100 2300 1700
Stiffness (Taber Units) Machine direction 9.0 24.0 27.0 4.0
Bulk Density (g/cm3) (@ 0.69 N/cm2) 0.19 0.30 0.20 0.19
Through-Plane Air Permeability (Gurley sec/100 cc) 4.0 15.0 5.0 5.0

AvCarb Process combines high quality with product flexibility and continuous improvement:

  • Stronger, Smoother MPL designs
  • Customizable Mechanical Properties
  • PFAs Free Substrate & MPLs
  • Widest & Longest Continuous Webs in the Industry

Gas Diffusion Systems (GDS)

AvCarb’s Gas Diffusion Layer papers are manufactured through a complex multi-step process that utilizes carbon fiber and a proprietary saturation ink that allows for optimal down-web and cross-web uniformity and most consistent performance. By altering the composition and loading of the saturation ink, the internal structure of the paper can be modified allowing papers to shift critical properties such as diffusivity, conductivity, mechanical strength, porosity, pore size, etc. By creating different structures with the same process and raw materials, the manufacturing cost is lower as customers get the benefit of volume production with different designs. AvCarb’s best in class quality and manufacturing flexibility provides the best customer value minimizing manufacturing scrap and costly re-builds due to low performing cells and providing best in class durability with GDL performance shown for over 38,000 hours of continuous operation in some systems.
TYPICAL PROPERTY AvCarb® GDS6130 AvCarb® GDS6250 AvCarb® MB-30 AvCarb® GDS3250 AvCarb® GDS3260 AvCarb® GDS2185 AvCarb® GDS2230 AvCarb® GDS2255 AvCarb® GDS2300 AvCarb® GDS5130
Base Paper (GDL) EP25 EP25 EP40 EP40 EP40 P75 P75 P75 P75 EP55
Nominal Thickness (μm) @ 0.05 Mpa 110 110 150 165 165 213 205 235 245 195
@ 1 MPa 165 165 205 225 225 250 260 275 290 270
Nominal Basis Weight (g/m2) 46 70 55 80 80 153 105 152 125 70
Break Strength (N/m2) Machine direction 2000 2000 2500 2500 2600 3200 4100 5400 4000 3200
Stiffness (Taber Units) @Machine Direction 4 5 10 10 11 28 22 28 28 30
@Cross Machine Direction 2 3 5 5 6 12 12 18 19 15
Bulk Density (g/cm3) 0.28 0.37 0.28 0.33 0.35 0.61 0.40 0.55 0.43 0.26
TP Resistivity (mΩ*cm2) @ 1MPa 10 10 10 11 11 23 10 20 10 10
Water Vapor Diffusivity (D/Do) 0.26 0.15 0.30 0.17 0.12 0.03 0.12 0.06 0.10 0.30

GDS Selection Guide

Use the table to determine the diffusivity level of the GDL required for your application. Based on the target thickness under compression, match the diffusivity level to determine the best GDL for your application.
Temperature Low RH (≤ 20%) Medium RH (20-60%) High RH (≥ 60%)
Low (≤ 50C) Med Diffusivity High Diffusivity High Diffusivity
Medium (60-80C) Low Diffusivity Med Diffusivity High Diffusivity
High (≥ 80C) Low Diffusivity Med Diffusivity High Diffusivity
Thickness Low Diffusivity Medium Diffusivity High Diffusivity
Low (≤ 180 μm) GDS6250 GDS6130
Medium (180-220 μm) GDS3260 GDS3250 MB-30
High (≥ 220 μm) GDS2185, GDS2255 GDS2300, GDS2230 GDS5130
Special Considerations

For highest operating current densities (>2 A/cm2) always choose a high diffusivity material
For membrane thickness ≤ 10 microns choose a smooth MPL version (replace 2nd digit in product code with a 9 – e.g., GDS6950, GDS2930, MB-39, etc.)
Asymmetric GDL combinations (e.g., different anode and cathode designs) often provide optimal performance, but are more complicated to process. Please contact an expert to discuss your needs.

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