Water Electrolyzers

Alkaline, PEM and AEM Electrolyzers

Pure Hydrogen generation

AEM Electrolyzers Alkaline Electrolyzers PEM Electrolyzers Porous Transport Layers for Water Electrolyzers

Porous Transport Layers for Water Electrolyzers

Porous transport layers are equivalent to gas diffusion layers of fuel cells. They facilitate the movement of the output gases, such as hydrogen and oxygen, while ensuring efficient and uniform distribution of the feed material (water) within the cell. These layers play a crucial role in enhancing overall water electrolyzer performance by optimizing reactant delivery and product expulsion, and promoting efficient electrochemical reactions.

Cathodic Porous Transport Layers

At the cathode side, carbon-based materials are the predominantly used porous transport layer owing to the stability of carbon under reducing conditions. enerally, thin (<1mm) sheets are used for fuel cell GDLs, while thicker panels (1.5–3.0 mm) are used for electrolyzers. While CAPLINQ can custom-make specific thicknesses, these are what our customer most often ask us for.

Graphitized Carbon Fiber 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 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

Anodic Porous Transport Layers

At the oxygen (anode) side of water elctrolyzers, the environment is much more corrosive because of usage of pure oxygen and application of potentials as high as 2 V. The highly oxidative environment at the anode corrodes the carbon-based LGDLs, thereby forming CO₂(Eqn. 1) and carbonate ions (Eqn. 2) in acidic and basic media, respectively. Carbon corrosion drastically reduces the the activity and stability of the anode during galvanic or electrolytic operations. For these reasons, metal-based PTLs, more commonly titanium and nickel-based GDLs, are used at the anode of and water electrolyzers.

Titanium as Anodic PTLs

Titanium fiber papers are the preferred PTLs at the anode of water electrolyzers due to the highly corrosive environment. Titanium offers excellent corrosion resistance, making them a preferred choice to maintain long-term performance and efficiency in these electrochemical devices.

Titanium fiber papers exhibit strong corrosion resistance in PEM water electrolyzers. They form a protective passivation layer that prevents direct contact with corrosive electrolytes, stabilizes the surface, and reduces defect-related corrosive reactions, improving device performance and durability.

LINQCELL^TM Titanium Fiber Paper Properties

Product	Porosity (%)	Thickness (um)*	Basis Weight (g)	Actual weight (g)**
LINQCELL TFP250	50–60	250	45.5	18.3–22.6
LINQCELL TFP250S	60–70	250	45.5	13.7–18.1
LINQCELL TFP400	50–60	400	72.8	29–36.3
LINQCELL TFP400S	60–70	400	72.8	22–29
LINQCELL TFP600	50–60	600	109.3	44–54.5
LINQCELL TFP600S	60–70	600	109.3	32.8–43.6
LINQCELL TFP800	50–60	800	145.7	58.3–72.9
LINQCELL TFP800S	60–70	800	145.7	43.7–58.2

Nickel as Anodic PTLs

Nickel fiber paper is also a valuable PTL in water electrolyzers and fuel cells, facilitating reactant transport and product gas removal while maintaining strong electrical conductivity. It serves as a cost-effective alternative to titanium fiber papers. Nickel fiber paper's durability and affordability make it a practical choice for PTL applications, particularly when stable electrical performance and cost efficiency are paramount.

Property	Titanium	Nickel
Electrical Conductivity	Moderate, lower than Nickel	High, excellent electrical conductor
Corrosion Resistance	Excellent, highly corrosion-resistant	Good, less corrosion-resistant than Titanium
Cost	Expensive	Affordable, cost-effective
Oxidation Under High pH	Resistant	Susceptible, can oxidize in alkaline conditions
Weight	Lightweight	Lightweight
Mechanical Strength	High, strong	Good strength
Thermal Conductivity	Moderate	High, excellent thermal conductor
Application Suitability	Most suitable for high-pH environments, such as alkaline fuel cells	Versatile, can be used in a wide range of environments, but may perform better in moderate pH values

It is important to consider specific application requirements, as the choice between Titanium and Nickel as a porous transport layers will depend on factors such as pH conditions, cost constraints, electrical and thermal performance, and material availability.

LINQCELL^TM Nickel Fiber Paper Properties

Product	Porosity (%)	Thickness (um)	Elongation (%)	Tensile Strength (MPa)
LINQCELL NFP250	40–90	250	≥8	5–8
LINQCELL NFP500	50–90	500	≥8	5–8

Stainless Steel as Versatile Anode and Cathode PTL

Discover CAPLINQ's stainless steel fiber felts—an innovative solution for fuel cells and electrolyzers, excelling in both anode and cathode applications. Engineered with highly catalytic alloy components (Ni, Co, Fe, Mo, and Mn), these felts optimize oxygen evolution reactions at the anode while showcasing exceptional durability and resistance to hydrogen embrittlement at the cathode.

CAPLINQ's stainless steel fiber felts come in three thicknesses– 250 (LINQCELL SFP 250), 600 (LINQCELL SFP 600), and 1000 (LINQCELL SFP 1000) µm, offering adaptability for various applications and providing a reliable and advanced solution to enhance the efficiency and resilience of your systems.

General Property Comparison of LINQCELL^TM Cathode Porous Transport Layers

Property	Carbon Cloth or Fabric	Graphitized Carbon Paper	Stainless Steel Fiber Paper
Electrical Conductivity	■■■□ Good	■■■■ High	■■□□ Moderate
Corrosion Resistance	■■■□ Good	■■■■ High	■■□□ Moderate
Compressibility	■■■□ Good	■■■■ High	■■□□ Moderate
Cost	■■■□ Cheap	■□□□ Expensive	■■■■ Cheapest
Weight	■■■■ Lightest	■■□□ Moderate	■□□□ Heavy
Temperature Stability	■■■■ Excellent	■■■■ Excellent	■■□□ Moderate

General Property Comparison of LINQCELL^TM Anode Porous Transport Layers

Property	Titanium	Nickel	Stainless Steel
Electrical Conductivity	■■■□ Good	■■■■ High	■■□□ Moderate
Corrosion Resistance	■■■■ High	■■□□ Moderate	■■■□ Good
Compressibility	■■□□ Moderate	■■■□ Good	■■■■ High
Cost	■□□□ Expensive	■■■■ Cheapest	■■■□ Cheap
Weight	■■■■ Lightest	■■□□ Moderate	■□□□ Heavy
Temperature Stability	■■■■ Excellent	■■■□ Good	■■□□ Moderate
Availability	■□□□ Rare	■■■■ Abundant	■■□□ Moderate

Note: The rankings provided are based on general properties and characteristics of carbon, titanium, nickel, and stainless steel. Actual performance may vary based on manufacturing processes, and environmental conditions. These rankings are intended as a broad overview and should not be the sole factor in decision-making. For precise and application-specific information, it is recommended to consult relevant scientific literature, engineering specifications, and industry experts. Additionally, advancements in materials science and technology may influence the properties of these materials over time. The rankings are subject to change based on new developments and research in the field. Contact us for your cathode and anode PTL needs.