Hangbo Alloy Group
Shanghai · Est. 2012
PEM and alkaline electrolyzers use nickel alloys for bipolar plates and cell frames. Learn which grades—200/201, 600, 625—resist caustic, high-purity H2, and how Hangbo supplies them.
Green hydrogen has moved from pilot scale to gigawatt-scale procurement, and the electrolyzer stack at the heart of every project is, quietly, a materials problem. Whether the technology is alkaline or proton-exchange-membrane (PEM), the cell must conduct current, contain a corrosive electrolyte, and survive years of thermal and pressure cycling without contaminating the product gas. Nickel and its alloys sit at the center of this design because no other affordable metal combines high catalytic activity for the hydrogen evolution reaction with the corrosion resistance alkaline and acidic electrolytes demand. This guide covers which nickel alloys belong in an electrolyzer and why, written for engineers specifying material and for procurement teams qualifying supply.
In an alkaline electrolyzer the electrolyte is typically 25–30% potassium hydroxide at 60–90°C. Few metals survive that combination with low hydrogen overpotential; nickel does, which is why porous nickel transport layers, meshes, and sintered electrodes are standard. In PEM electrolyzers the acidic, fluorinated membrane environment and high anodic potentials push the noble-metal-loaded side, but the bipolar plates, porous transport layers, and end-plate structures on the cathode side still lean heavily on nickel for cost and corrosion reasons. The practical result is that a single gigawatt project can consume hundreds of tonnes of nickel-based material across plates, frames, and porous components.
Nickel's value is not only chemical. Its moderate density, good formability, and established welding and plating routes make it manufacturable at the volumes electrolysis now requires. The constraint is purity: trace elements that are harmless in structural service can poison a catalyst layer or raise the cell voltage enough to erode project economics, so mill traceability matters more here than in most alloy applications.
Nickel 200 and Nickel 201 (UNS N02200 / N02201) are the baseline choices for alkaline cell frames, pure nickel meshes, and current collectors. Nickel 201 is preferred where service exceeds about 315°C or where carbon content must stay extremely low to avoid graphite precipitation at welds; for typical alkaline electrolyzer temperatures either grade is acceptable, but 201 is the safer default for welded fabrications. Alloy 600 (UNS N06600, Ni-Cr-Fe) is widely used where some strength and oxidation resistance are needed at the cell boundary, such as end plates and structural frames, and tolerates the caustic well.
For components that also see mechanical load, crevice conditions, or mildly acidic excursions—such as bipolar plates and gasketed frames—Alloy 625 (UNS N06625) is specified for its chloride resistance and strength. Titanium and platinum-group coatings still appear on the most aggressive anodic surfaces, but the structural and porous nickel backbone of the stack is, in most designs, a nickel alloy problem. Our hydrogen embrittlement guide explains why the hydrogen itself, not just the electrolyte, drives some of these choices.
Electrolyzer materials face two failure modes that are easy to underestimate. The first is ordinary caustic or acidic attack that thins a plate or leaches metal into the electrolyte, raising impurity levels in the hydrogen stream and triggering downstream purification cost. The second is hydrogen-related damage: at the cathode, atomic hydrogen can enter the metal, and although nickel alloys are far less susceptible than high-strength steels, the design must still respect operating temperature and stress so that embrittlement risk stays negligible. Our companion articles on hydrogen embrittlement and on high-temperature hydrogen attack cover the metallurgy in detail; for electrolyzers the operating envelope is mild enough that nickel alloys are comfortably inside it.
Purity also has a thermal dimension. Where electrolyzer outflow is cooled or where hydrogen is later liquefied or stored cryogenically, the same nickel family that survives the cell also performs at low temperature, which is why cryogenic nickel alloy service is a useful cross-reference for balance-of-plant and storage equipment on the same site.
Because electrolyzer material is both corrosion-critical and purity-critical, procurement should demand more than a grade name. Ask for EN 10204 3.1 mill certificates with full chemistry including trace elements, verified by third-party inspection where the program allows. Specify surface condition: machined or pickled-and-passivated plates reduce the risk of embedded contaminants that elevate cell voltage. Our passivation guide explains the surface treatments that protect nickel in aggressive electrolytes, and our welding guide covers the joint quality needed for leak-tight cell frames.
For stack builders, consistency between heats matters as much as any single property: matched thermal expansion and stable resistivity keep cell performance uniform across a multi-hundred-cell stack. Work with a supplier who can hold chemistry and finish across the full production run, not just the first article.
Both work at typical alkaline temperatures, but Nickel 201 is the safer default for welded fabrications because its very low carbon content avoids graphite precipitation at welds. Choose 200 only when the lower-carbon grade is unavailable or when the part is not welded; for most cell frames and current collectors, 201 is preferred.
Yes, within the normal electrolyzer envelope. Nickel alloys are far less sensitive to hydrogen embrittlement than high-strength steels, and operating temperatures and stresses in alkaline and PEM cells stay well inside safe limits. The higher-temperature, high-pressure refinery cases that demand special care are described in our guide on high-temperature hydrogen attack—a different, more severe regime than electrolyzer operation.
As a dedicated nickel alloy manufacturer, Hangbo Alloy Group supplies Nickel 200/201, Alloy 600, and Alloy 625 as plate, sheet, bar, and wire for bipolar plates, porous transport layers, and cell frames, with full ASTM/ASME documentation, EN 10204 3.1 certificates, and surface finishes suitable for pickling or passivation before cell assembly.
As a dedicated nickel alloy manufacturer serving power generation, chemical processing sectors, Hangbo Alloy Group supplies the grades discussed here across all standard product forms with full ASTM/ASME documentation and EN 10204 3.1 certification. Our material is specified for applications where corrosion resistance, high-temperature strength, and traceable quality are non-negotiable. See our production & testing facilities for more on how every heat is verified.