Core Advantages of Microporous Nickel Foam as a Diffusion Layer (GDL/PTL) in AEM Electrolytes
Apr 20, 2026
I. Core Advantages of Microporous Nickel Foam as a Diffusion Layer (GDL/PTL) in AEM Electrolytes
1. Excellent Electrical and Electron Conductivity
- High intrinsic conductivity of metallic nickel; its three-dimensional interconnected network ensures efficient electron conduction and low interfacial contact resistance.
- Superior to carbon-based materials (easy to anolyze in alkaline environments) and titanium-based materials (high cost); well-suited to the alkaline and high-potential environment of AEM.
2. Three-Dimensional Through-Pore Structure (Mass Transfer/Reaction Advantages)
- High porosity (90%~98%) + hierarchical pores: macropores (rapid gas expulsion), mesopores/micropores (water distribution, three-phase interface).
- Extremely large specific surface area: provides more active sites for adhesion, improving catalyst utilization.
- Good mechanical strength and moderate flexibility: high fit during compression assembly, less prone to brittleness.
3. Alkali Stability and Catalytic Synergy
- Nickel exhibits corrosion resistance and structural stability under the strong alkalinity and high temperature (50~80℃) of AEM. - Nickel itself possesses weak OER/HER catalytic activity, which synergistically enhances its effect with the catalyst layer.
4. Cost and Process Friendly
- Compared to titanium felt and precious metal coatings, the raw material and preparation costs are lower.
- Easy to cut, modify, and load catalysts (electrodeposition, electroless plating, coating).
II. Why is the PTL/MEA interface the core battleground for optimization?
The performance (voltage, current density, lifetime) of an AEM electrolyzer is highly dependent on the interface. Losses mainly come from: ohmic contact, activation, and mass transfer.
1. Interface Contact and Ohmic Loss (Most Critical)
- Rough surface and sharp pores in nickel foam: easily puncture the AEM film, causing localized stress concentration and uneven contact.
- Improper pore size/flatness of microporous nickel foam:
- Pores too large → Small contact area, high contact resistance
- Pores too small → Membrane easily embedded in pores, membrane damage, hindered ion conduction
- Optimization directions:
- Surface micro/nano modification (powder layer, etching, oxidation) → Smoother, better fit
- Gradient pore structure (inner micropores/mesopores, outer macropores) → Balances contact and mass transfer
2. Three-phase interface (solid-liquid-gas) and reaction kinetics
- Interface determines: Water transport, OH⁻ conduction, bubble desorption, effective catalyst utilization.
- Problems:
- Poor interface wettability → Local water shortage, mass transfer polarization
- Bubble retention → Covering active sites, dramatic increase in overpotential
- Weak bonding between catalyst layer (CL) and PTL → High resistance, catalyst detachment
- Advantages of nickel foam: Three-dimensional pores can "lock in water" and facilitate rapid bubble detachment.
3. Interface Stability and Lifespan (Main Cause of Long-Term Degradation)
- The interface experiences the most severe material interactions, stress, dissolution, and ionomer degradation.
- Failure Modes:
- PTL and CL delamination/stripping
- Localized membrane thinning, pinholes, short circuits
- Nickel dissolution contaminates the membrane/cathode
- Interface optimization directly improves durability and reduces degradation rate by an order of magnitude.
4. Interface Bottlenecks at High Current Densities (Key to Industrialization)
- At ≥1–2 A/cm²:
- Gas production surge → Interface prone to gas blockage, mass transfer limit
- Heat concentration → Accelerated aging of interface materials
- Only interface optimization can truly realize the high conductivity and high specific surface area of nickel foam.
III. Core Strategies for Optimizing the Interface of Microporous Nickel Foam PTL/MEA
1. Surface Microstructure Modification
- Coating with microporous nickel powder/nano-nickel layer → Smooth surface, prevent membrane puncture, increase contact area
- Chemical etching/oxidation → Create nano-rough surface, enhance bonding, improve wetting
2. Gradient Pore Structure Design
- Inner side (membrane side): Small/micropores (5–20 μm) → Good contact, water retention, stable three-phase interface
- Outer side (channel side): Large pores (30–100 μm) → Rapid venting, reduced gas blockage
3. Interface Bonding and Integration
- Direct catalyst growth/electrodeposition on nickel foam → Reduce interfacial resistance, prevent detachment
- Ionomer (AEI) interface regulation → Enhance OH⁻ conduction, improve adhesion and stability
4. Surface Energy/Wettability Regulation
- Hydrophilic modification → Uniform water distribution, reduce dry areas
- Moderate hydrophobic sites → Rapid bubble desorption and flood prevention
Summary
- Microporous nickel foam is the preferred choice for AEM diffusion layers: high conductivity, high stability, high specific surface area, and low cost.
- The performance ceiling is not in the material itself, but at the PTL/MEA interface.
- Interface contact, three-phase interface, interface stability, and high current density mass transfer must be the core optimization battlegrounds to truly unleash the advantages of nickel foam and achieve low-voltage, high-current, long-life AEM electrolyzers.
