Nickel fiber felt is a porous sheet built from sintered nickel fibers, not a cellular foam and not a woven or knitted wire cloth. In alkaline water electrolysis (AWE / ALK) and anion-exchange membrane water electrolysis (AEMWE), buyers and researchers discuss it as an electrode substrate, a porous transport layer (PTL), or a gas/liquid diffusion medium. The sheet is not the catalyst layer by itself, and a foam PPI value is not a felt specification. This guide covers the usual levers—porosity, thickness, and how to read published results—plus what to send for a quotation. It is not a ranking claim or a list of fixed HuiRui catalogue numbers.
Felt is not foam and not mesh
Drawings that say “nickel porous metal” still leave the structure ambiguous. The three common nickel forms answer different questions:
- Nickel fiber felt is a sintered fiber network. Start with thickness, porosity (and how it will be checked), cut size, and whether the sheet is bare or coated. Product context: nickel fiber felt (nickel-fiber media).
- Nickel foam is a cellular open-pore sheet. Buyers usually start with thickness, a pore-size figure (often PPI), and porosity; see nickel foam PPI: pore size, thickness and porosity and nickel foam for alkaline water electrolysis.
- Nickel woven or knitted mesh is specified by mesh count or opening and wire diameter, or by knitted construction and free versus loaded thickness; see nickel mesh for alkaline water electrolysis and the structure overview nickel foam, nickel fiber felt or nickel mesh.
If you are still choosing the electrolyzer type, ALK, PEM, AEM and SOEC outlines where nickel parts are typical and where titanium is the usual choice. Titanium felt for PEM anode PTLs is a different metal and duty; see titanium fiber felt porosity and thickness for PEM.
Where nickel fiber felt shows up in ALK and AEM
Alkaline (AWE / ALK). Yang et al. (2020) compared three nickel electrodes in a zero-gap, flow-through alkaline electrolyzer: foam, microfiber felt, and nanowire felt. In that study the microfiber felt balanced surface area against bubble removal better than the nanowire felt (which trapped gas) and the foam (which had less area). Those results describe their cell and electrodes, not a universal HuiRui thickness or porosity target.
AEMWE. Nickel fiber and nickel felt sheets are widely discussed as anode PTLs. Kreider et al. (2025) varied morphology and composition of fiber-based PTLs in AEMWE with and without a Co3O4 catalyst layer. Park et al. (2022) compared nickel foam and nickel felt as Ni-based anode PTLs against a conventional titanium felt reference in their AEMWE cells. Razmjooei et al. (2021) added a nickel-based microporous layer on top of a PTL (NiMPL-PTL) to lower interfacial contact resistance and transport polarization in an AEM electrolyzer operated with pure water. None of these papers sets a single “correct” porosity or thickness for every stack.
Porosity, thickness and the other levers
Porosity. Porosity is the void fraction of a defined bulk volume. Two felts can share a similar porosity and still differ in fiber diameter, pore-size distribution and surface finish. Kreider et al. reported three commercial-style Ni fiber PTLs in that study at about 215 μm / 84% porosity / 44 μm average pore size; about 270 μm / 61% / 18 μm; and about 530 μm / 60% / 16 μm. For those Ni fiber PTLs with a ~2 μm Co3O4 layer, decreasing pore size and porosity gave about a 20% higher current density at 2 V in 1 M KOH in their cells. Those figures are study samples, not a HuiRui stock list.
Thickness. State the finished thickness you need, and whether it is a free (uncompressed) thickness or a thickness under a load already written on your drawing. Those labels are not interchangeable. Published AEMWE work often discusses nickel felt or fiber PTLs on the order of a few hundred micrometres to about half a millimetre (for example the Kreider Ni fiber set above, and Park’s Ni-felt versus Ni-foam comparison). Treat every published millimetre value as that paper’s sample, not as a default for your quotation.
Pore size and fiber diameter. If you already have a mean pore diameter, a pore-size distribution, a fiber diameter, or a measurement method, send them. PPI belongs to foam discussions and is not a direct felt specification (43373).
Role in the cell. Say whether the sheet is a catalyst substrate, a PTL between catalyst and flow field, a flow-through electrode, or another duty. Park et al. found that pore architecture (foam versus felt) changed mass-transport behaviour in their AEMWE anodes; Razmjooei et al. showed that an added nickel microporous layer changed contact and transport resistance. The right lever depends on that role.
Compression and contact. Fiber sheets can change thickness under stack load. Quote a compressed thickness only if your documents already define the load and the method. Contact resistance at the catalyst or bipolar-plate face often matters as much as bulk porosity.
Coating, or none. Say whether you need a bare nickel sheet, a coated substrate, or a complete catalyst-coated electrode. Coating chemistry, loading and which face is coated are project-specific.
Sheet size and edges. Give length × width or a cut-part drawing, plus any edge, flatness or tab requirement you already have.
Felt versus foam for ALK/AEM: a quick comparison
| Form | Structure | Where it tends to fit | What to specify first |
|---|---|---|---|
| Nickel fiber felt | Sintered fibers | ALK electrodes / supports; AEMWE PTLs and diffusion media | Thickness (free or loaded), porosity if known, cut size, bare or coated |
| Nickel foam | Cellular open pores | Many AWE electrode studies; some AEMWE PTLs | Thickness, PPI or measured pore size, porosity (43373, 36882) |
| Nickel mesh | Woven or knitted wires | Current distributors and many tank electrodes | Mesh count / opening / wire diameter, or knitted free vs loaded thickness (35277) |
Park et al. (2022) reported that, in their AEMWE cells, an optimized Ni-foam anode PTL outperformed Ni-felt on mass-transfer grounds because of the foam’s interconnected pores. That is a study-specific structure comparison, not a rule that foam always replaces felt on every drawing. If cost versus performance is the next question after structure, see nickel felt cost and performance.
What to send for a quote
You do not need a complete laboratory list to contact HuiRui. A sketch, a drawing, or an approximate size and duty is enough to start. The items below help when you already have them:
- The job: ALK electrode or support, AEMWE PTL / diffusion medium, flow-through electrode, or another use.
- Electrolyte context if known (for example concentrated KOH for classic AWE, dilute KOH or pure-water AEMWE feed)—compatibility still has to be assessed for the full stack, not inferred from the product name.
- Thickness, and whether that number is free or under a load already on the drawing.
- Target porosity if your project already states one, and how it will be checked.
- Any fiber diameter, mean pore size or measurement method you already use.
- Cut size or blank size, quantity, and whether you need samples first.
- Bare or coated; if coated, the type and which face(s), or a pointer to your coating specification.
- Any flatness, edge or inspection record required by the project.
We supply nickel fiber felt. Related forms include nickel foam and nickel mesh products linked from the structure and AWE guides above. Dimensions, porosity, thickness condition and any coating are confirmed per enquiry. Product pages may list illustrative ranges for quotation discussion; do not treat those ranges, or the literature results above, as verified cell performance for every design. Send the drawing and the items you already know, and we will reply with what we can make.
References
- F. Yang, M.J. Kim, M. Brown and B.J. Wiley, “Alkaline Water Electrolysis at 25 A cm−2 with a Microfibrous Flow-through Electrode”, Advanced Energy Materials (2020). https://doi.org/10.1002/aenm.202001174
- M.E. Kreider et al., “Porous Transport Layers for Anion Exchange Membrane Water Electrolysis: The Impact of Morphology and Composition”, ACS Electrochemistry (2025). https://doi.org/10.1021/acselectrochem.4c00207
- J.E. Park et al., “Effect of pore structures in nickel-based porous transport layers for high-performance and durable anion-exchange membrane water electrolysis”, International Journal of Energy Research (2022). https://doi.org/10.1002/er.8331
- F. Razmjooei et al., “Increasing the performance of an anion-exchange membrane electrolyzer operating in pure water with a nickel-based microporous layer”, Joule (2021). https://doi.org/10.1016/j.joule.2021.05.006