Ionomer

Understand

What this part does and what decides it

Why it matters

The ionomer holds the catalyst particles together while opening a path for ions. Too little and the catalyst layer breaks up; too much and ion transport improves, but the polymer covers the catalyst particles and blocks electron transport. Loading governs electrode performance, and it is a different judgement from choosing a membrane. How much you need follows from the ratio against catalyst weight, not from electrode area. One number separates the grades: ion exchange capacity, written IEC. It is how many ion exchange groups sit on one gram of polymer, in meq/g. That is the IEC in the strip above and in the table below.

IN OUR OWN SYSTEMS

The catalyst layer of our own HXP-ca cathode uses a binder from this family. We have not stayed on a single grade: we bought A and C and compared them side by side. So if you give us your conditions we can weigh the grades against each other on the same basis.

Background

What a higher ion exchange capacity changes

The figure sets how densely hydroxide ions can move through the catalyst layer. A higher figure improves ion transport but holds more water, which can soften the catalyst layer. A lower figure gives the opposite: a firmer structure with poorer ion transport. The grades are split by this one number, not by electrode position. The grade letters are the order: A is the lowest, B the middle, C the highest. The figures themselves are in the comparison below.

Which electrode it goes into

It goes into electrodes where the catalyst is applied as particles, and not into electrodes where it is not. Our own HXP-an anode grows NiFe-LDH directly on a nickel foam substrate as one piece, so it uses no ionomer. The HXP-ca cathode uses Pt/C and PtRu/C particles, so it does. If your build applies a particulate catalyst on the anode as well, the ionomer goes in there too as the binder. That is why the first thing we confirm before quoting is whether the catalyst is applied as particles.

What you do with the powder

It arrives as a powder in a bottle. You dissolve it in solvent, mix it with the catalyst to make an ink, and coat that ink onto the substrate to form the catalyst layer. The quantity you need therefore follows from the loading ratio against catalyst weight, not from electrode area. Tell us that ratio when you ask about quantity and we can work out the number of bottles.

Choose

The options and the models we handle

What you can choose

Start here and we adjust to your conditions. We can usually source what is not listed.

	Grade A	Grade B	Grade C
IEC	2.35 meq/g	2.79 meq/g	3.55 meq/g
Where it fits	When the catalyst layer has to stay firm	When you want the middle ground	When ion transport comes first
	Holds the least water of the three, so the catalyst layer is least likely to soften.	The midpoint between A and C, leaning neither towards catalyst-layer firmness nor towards ion transport.	The best ion transport of the three, at the cost of holding more water.
	Quote this option	Quote this option	Quote this option

All three grades are powders and the order unit is the same, so the grade is the only thing to settle. If you do not have a target ion exchange capacity yet, tell us the catalyst and the loading ratio and we will work out which grade fits.

Models we supply

The three Versogen PiperION grades we supply. Being one family, the only axis that changes is ion exchange capacity; form, order unit and origin are the same whichever grade you take, so they are listed under how we supply it below. IEC figures are the manufacturer’s brochure values on an OH⁻ basis. Prices are quoted against your conditions.

Model	IEC	Quote this
PiperION A	2.35 meq/g	Quote this
PiperION B	2.79 meq/g	Quote this
PiperION C	3.55 meq/g	Quote this

Order

What to settle before a quotation

What often goes wrong

Only what has come up more than once in real enquiries.

Do we need ionomer at all

Is it the same thing as the membrane?

No. The membrane separates hydrogen from oxygen; the ionomer binds the electrode catalyst layer. They are even ordered differently, by the sheet and by the bottle.

Does the anode need ionomer too?

It does if the catalyst is applied as particles, and it does not otherwise. Our own anode grows the catalyst directly on the substrate as one piece, so it uses none. If your build uses a particulate catalyst, the ionomer goes in on the anode side as the binder.

Which grade to take

Which grade should we take?

If you already have a target ion exchange capacity, we match it. If not, tell us the catalyst and the loading ratio and we will work it out with you. We supply all three grades, so we can settle on the one that fits your conditions.

What we confirm before quoting

Once these are set, selection and quotation happen in one step. If they are not, we start there.

Whether the catalyst is applied as particles
Target IEC grade, if you have one
Catalyst type, loading ratio and quantity by the bottle
What it is for: single cell, short stack or full stack
When you need it

Supply terms

Supply scope: Domestic delivery; we carry the overseas purchase and customs
Order unit: 0.8 g bottles
Origin: United States
Warranty: We verify conformity to the manufacturer specification. Performance under your fabrication conditions is not covered
Specification basis: We re-confirm the current manufacturer specification before placing an order