Graphitized Carbon Plates and Papers

Porous, compressible, graphitized resin bonded carbon fiber papers

Graphitized Carbon Papers for Electrochemical Devices

Graphitized Carbon Papers

Gas Diffusion Layer (GDL) sheets are porous, graphitized, resin bonded carbon fiber papers and multi-ply panels specifically designed for use in PEM, AEM, DMFC and PAFC fuel cells, Electrolyzers, Humidifiers and Other Electrochemical Devices. 

These products are optimized, among other, for their electrical conductivity, mechanical strength and durability, gas/air permeability and water management. GDLs are available in a wide range of standard and custom grades, densities, sizes and materials for fuel cells, electrolyzers, humidifiers, specialty batteries and other electrochemical applications. They can be coated, inked or loaded as Anode or Cathode catalyst layers for Membrane electrode assemblies. CAPLINQ offers the full range of GinerELX (previously known as Engineered Fibers Technology) product line while we also offer our newly developer LINQCELL product line.

All of our default Gas difussion layer panel sizes are either 20x20 or 40 x 40cm. 55 x 55cm only remain for some spectracarb grades that are being discontinued. Custom sizes are available for special orders and larger quantities. Sheet thicknesses range from as low as 0.18mm (7mil) to as thick as 2.9mm (114mil). Densities of the panels range from as low as 0.5 g/cc to 0.8 g/cc.

Custom sizes, machined discs, and other customer defined shapes, as well as machining, water proofing and surface grinding services are also available. Contact us with your query.

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Product Selector Guide

Graphitized Carbon Papers and Plates
Product Thickness Thickness (mm) Density (g/cm3) Basis weight (g/m2) Through-Plane Resistance (mΩcm2) Through-Plane Resistivity (mΩcm) Voltage Loss (mV)
LINQCELL GDP 180 0.007" 0.18 50 7 - -
LINQCELL GDP 210 0.008" 0.21 - 51 10 - 14
LINQCELL GDP 240 0.009" 0.24 - 90 15 - -
LINQCELL GDP 340 0.013" 0.34 - 90 10 - -
LINQCELL GDL 1500 0.059" 1.5 0.60 858 13.32 90.6 24.3
LINQCELL GDL 1500B 0.059" 1.5 0.60 670 21 140 39
LINQCELL GDL 1850 0.072" 1.85 0.85 1562 13.18 70.5 25.5
LINQCELL GDL 2200 0.086" 2.2 0.6 1550 17 110 35
LINQCELL GDL 2900 0.011" 2.9 0.60 1734 24.57 87.7 27.6

All values are indicative and subject to tolerance



Spectracarb 2050A properties (Discontinued Q4 2021)
Product Thickness Thickness (mm) Density Required Loading for 12.5% ± 0.5% Strain Through-Plane Resistivity Standard size
Spectracarb 0850 .0075" ±.001"

0.19 ±0.02 0.5 g/cm³ ± 0.075 

100 lbf/in² ± 50

100 mOhm-cm @175 lbf/in² 16 x 16"
Spectracarb 1050 .011" ±.001" 0.28 ±0.02 0.5 g/cm³ ± 0.075  100 lbf/in² ± 50 100 mOhm-cm @175 lbf/in² 16 x 16"
Spectracarb 1550 .0145" ±.001" 0.37 ±0.02 0.5 g/cm³ ± 0.075  100 lbf/in² ± 50 100 mOhm-cm @175 lbf/in² 16 x 16"
Spectracarb 6060 .06" ±.005" 1.5 ±0.12  0.6 g/cm³ ± 0.075   300 lbf/in² ± 100 100 mOhm-cm @175 lbf/in² 22 x 22"
Spectracarb 7090 .064" ±.003" 1.6 ±0.07  0.775 g/cm³ ± 0.075   400 lbf/in² ± 150 100 mOhm-cm @175 lbf/in² 22 x 22"
Spectracarb 7090XT .084" ±.003" 2.1 ±0.07  0.775 g/cm³ ± 0.075   400 lbf/in² ± 150 100 mOhm-cm @175 lbf/in² 22 x 22"

Frequently Asked Questions

Frequently asked questions about Graphitised carbon plates

What is GDL Wet proofing?

A very common technique that is applied on GDLs is Wet proofing. Wet proofing the panels improves the water transport, increasing the total power generation. Additionally, wet proofing can stop GDLs from shedding carbon particles which helps with GDL handling.

Wet proofing Gas diffusion layers can be achieved by teflon dispersion or by applying hydrophobic treatments.

What is the GDL role in the assembly?

Gas diffusion layers structurally help the stack withstand the extension caused by the water absorbency. In addition to that, they aid with heat transfer, electrical surface conductivity, and the removal of excess water from the electrodes that is produced by redox reactions.

Finally, and most importantly, they clear the path for the Fuel and the Oxidizing agent towards the catalyst layers.

Learn More

Gas diffusion layers

Gas diffusion layers are mainly based on Carbon cloth, felt graphite or Carbon paper and they can be treated to acquire various properties. They ensure the uniform distribution of reactive gases on the surface of the electrodes, and they also aid the transport of electrons to or from the external electrical circuit.

Their two main roles are:

  1. Substrates for Electrodes / Catalyst layers
  2. Gas diffusion layers for 5 layer membrane assemblies

As an electrode we combine them with a catalyst ink to create the electrodes that go on either side of the ion exchange membranes.

For example they can be used as Cathode current collectors for PEM electrolyzers.

PEM water electrolysis uses electricity to split water into hydrogen and oxygen. A typical PEM eletrolyzer operates between 60°C and 90°C under pressures between 1 and 20 bars. An important part of the assembly is the porous current collector.

Main Functions of the current collector:

  • Current conduction BiP to electrodes
  • Medium to transport H2O and O2
  • Mechanical Support of MEA

Desired Properties of the collector are low Interfacial Contact Resistance, high electrical conductivity, structural stability and compressibility and finally Electrochemical corrosion and Hydrogen embrittlement resistance

As a, real, Gas diffusion layer we use them for what they really are. In a MEA5 we have the following order (see image above):

  1. Gas diffusion layer
  2. Anode
  3. Ion exchange membrane
  4. Cathode
  5. Gas diffusion layer

Gas diffusion layers structurally help the stack withstand the extension caused by the water absorbency. In addition to that, they aid with heat transfer, electrical surface conductivity, and the removal of excess water from the electrodes that is produced by redox reactions. Finally, and most importantly, they clear the path for the Fuel and the Oxidizing agent towards the catalyst layers.


Microporous layers and PTFE

Gas difussion layers can be treated with extra Microporous layers and PTFE.

The main properties of GDLs containing PTFE and MPL are that they improve water transport and management.

Because water retention reduces power generation, GDL treated with PTFE (Teflon) can make the material hydrophobic and improve water transport. Furthermore, the GDL with MPL treatment helps to reduce contact resistance between the GDL and catalyst layer, limit catalyst loss to the GDL interior, and improve water management by providing effective water transport.

These changes will result in higher through plane resistance so the density might need to be lowered to compensate for this increase. As an added note, thicker plates will see lower water management results from these treatments. They are more effective for thinner papers or plates.

Testing Methods


Resistance and Resistivity

Standard: Reference to ASTM C611-98

In house test method:We are Utilizing TSURUGA 3566 ( Battery Internal Resistance AC Tester) to make resistance measurements.  Additionally we are using our in house tools plus a small heat press facility.

Test piece size: Circular test piece with diameter of 5cm for which was cutted by mold.
Test pressure: 200 psi (14.1 kgf/cm2)
Hydraulic cylinder area:9.7 cm2

Test data:

  • bulk resistace = R:
  • Cutted piece area = A,
  • the thickness under tested pressure = t

    Calculation formula:   rt = (R x A)/t (Ωcm)  or Rt = R x A (Ωcm2)



Voltage Loss at 500mA/ cm² and 20N/ cm² is measured between a gold plated copper stamp and a gold plated base plate

Graphitized Carbon Panels

Presented at Hannover Messe April 2016

Graphitized carbon fiber plate Applications

Graphitised carbon fiber papers have multiple uses but their main applications are typically gas diffusion layers or the base for the anode and cathode assembly sides. These are popular products for electrolyzers, PEM and AEM fuel cells, electrochemical devices and other specialty applications.

When used as Fuel cell electrodes they have very high strength, high conductivity and high durability. The GDLs have good air permeability and moisture transport and can be used for lab scale prototypes to mass commercial scale manufacturing.

PAFC (Phosphoric acid fuel cell) are mostly used for stationary power, PEM and AEM fuel cells for transportation power and eletrolyzers, well, they are electrolyzers. GDLs have been successfully used for fuel cells utilisation in the Asian markets and have powered the transportation grid for the Olympics and the World Expo.


GDL production process

There are multiple steps to ensure our Gas diffusion layers are meeting the expected application requirements.

Typical process looks like the following:

  1. Carbon handsheet production (wet laid process)
  2. Thermoset resin impregnation
  3. In process inspection/Molding Panel preparation
  4. Compression molding/Trim
  5. In process inspection - Testing/Furnace stack preparation
  6. Graphitization
  7. Final inspection/Evaluation 

Our technical expertise with materials development along with our established supply chain and engineering management is key to produce a consistent and high level graphitised carbon plate.

If quantity makes sense we are open to produce and provide alternative thicknesses and grades


A short history of Spectracarb

In December 2018 GinerELX acquired the entirety of the Engineered Fibers Technology (EFT) company including branding, manufacturing, stock and all of the company’s assets while naturally inheriting their entire customer base. As part of their acquisition, GinerELX analyzed the existing business model and realized that they had to completely transform and reorganize the costs and production lines, reevaluate the product portfolio and manufacturing process to ensure that they can continue providing exceptional quality and service.As a result, effective August the 1st, GinerELX has adapted or completely removed some of the product lines to reflect the services GinerELX’s clients mostly need.

But the story didn't end there. Shortly after, GinerElX was acquired by Plugpower. Plugpower decided to keep all Spectracarb grades for their in house electrochemical needs and not distribute or sell to external parties. Hence Spectracarbs are no longer available for purchase after the end of 2021.

Caplinq used their long manufacturing experience and expertise to develop alternatives for all the popular legacy grades that are now branded under our LINQCELL GDL trade name.

You find them listed on our website or contact us for additional information.


Legacy Spectracarb product codes

  • 2050 HF: Other special grades include “2050 HF” with higher mean pore size and increased permeability.
  • 2050 HT: Spectracarb GDL can also be manufactured in the density and thickness ranges shown above, but using modified processing to achieve higher electrical conductivity and improved corrosion resistance with our ”2050 HT” Series for use in PAFC and other special products.
  • 2050 L: Spectracarb GDL thin papers and thicker panels can also be provided on special order in a “2050 L” grade which is carbonized at a lower maximum temperature to provide a lower-cost product for humidifiers and other special products.
  • 2050 P: Both papers and panels can also be provided on special order in our “2050 P Series” where additional purification can be conducted to provide trace elements
  • 2050 WP: Wet proofed grades incorporating a microporous hydrophobic layer of any of the Spectracarb series can be provided through a partner company.
  • Customer Specific Grades: It is also possible to make Hybrid constructions in the Multi-layer constructions. Contact us to discuss any special requirements, or for the design and production of grades for your specific requirement.
  • 2225 Activated fabric is also discontinued.