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Genius Steampunk Scientist Developing Proton Exchange Membrane Water Electrolyzer

Is Smoltek Hydrogen ahead of the game?

How does Smoltek's hydrogen business division compare with other PEM electrolyzer players? Smoltek Hydrogen’s president, Ellinor Ehrnberg, attended the 244th ECS meeting in Gothenburg and has the answer. In this interview, she also talks about the challenges of the industry and ways to deal with them.

In early Octo­ber 2023, The Elec­tro­chem­ic­al Soci­ety (ECS) held its 244th meet­ing in Gothen­burg. Smol­tek Hydro­gen was there with both a speak­er at the con­fer­ence and a booth at the exhib­i­tion. The pur­pose was mainly to meet poten­tial part­ners and cus­tom­ers. But it was also an excel­lent oppor­tun­ity for Smol­tek to bench­mark itself against some of the world’s lead­ing research­ers from industry and academia.

ECS 244th meeting

Smol­tek wasn’t alone at the ECS 244th meet­ing. More than 3,400 research­ers and indus­tri­al­ists participated.

“Many came from the USA, which is the home of ECS,” says Ellinor Ehrn­berg. “But a sur­pris­ing num­ber came from Asia, espe­cially Japan and Korea. I think it’s great because there are two giant LNG countries.”

LNG countries

LNG-coun­tries? What does it mean?

“Just as coal has been an import­ant energy source for the industry in Ger­many, lique­fied nat­ur­al gas, LNG, is an import­ant energy source for the industry in Japan and Korea,” Ellinor Ehrn­berg explains.

“Both coun­tries import large amounts of LNG. Their indus­tries need to replace nat­ur­al gas with some­thing more cli­mate-friendly. As they are used to handle energy gas, hydro­gen is a nat­ur­al altern­at­ive ”, says Ellinor Ehrn­berg, and uses Toyota as an example:

“Toyota dares to devel­op a mid-size hydro­gen fuel cell vehicle while the rest of the auto­mot­ive industry solely focuses on bat­tery-powered cars. I believe the con­fid­ence to go their way comes partly from Japan’s exper­i­ence with LNG.”

Opportunity for comparison

It’s not because Ellinor Ehrn­berg is a pro­ponent of fuel cells that she is happy to see many from Japan and Korea at the con­fer­ence and on the exhib­i­tion floor.

“Pro­ton-exchange mem­branes are used in both fuel cells and elec­tro­lyz­ers. This means that many tech­no­lo­gic­al advances made in the research and indus­tri­al­iz­a­tion of mem­branes for fuel cells are dir­ectly trans­fer­able to PEM elec­tro­lyz­ers and vice versa,” says Ellinor Ehrnberg.

The ECS 244th meet­ing attrac­ted many top tal­ents in the industry, many of whom are from Asia, giv­ing Ellinor Ehrn­berg and her team a unique oppor­tun­ity to bench­mark their tech­no­logy with others.

“Much research and devel­op­ment of pro­ton-exchange mem­branes is done without pub­lish­ing res­ults. But, most people tend to be out­spoken and share inform­a­tion at an event like this. So, we need to par­ti­cip­ate to learn more about oth­ers’ approaches and results.”

Before we exam­ine the approaches taken by dif­fer­ent com­pan­ies and labs and the res­ults they have achieved, we must under­stand the prob­lem that fuel cell and elec­tro­lyz­er man­u­fac­tur­ers are try­ing to solve.

The center of the magic

A mem­brane is at the cen­ter of the magic, where water is split into hydro­gen and oxy­gen. It blocks elec­trons but allows pro­tons to pass through – hence the name Pro­ton Exchange Mem­brane (PEM).

On both sides of the mem­brane are elec­trodes. An elec­trode is a fancy term for an elec­tric­al con­duct­or in con­tact with a non­metal­lic part of a cir­cuit (in this case, water). One of the elec­trodes is con­nec­ted to the pos­it­ive ter­min­al of a power source and is called the anode. The oth­er is con­nec­ted to the neg­at­ive ter­min­al of the same power source and is called the cath­ode.

The trick

The power source wants to push out elec­trons at the cath­ode and pull in an equal num­ber at the anode. How­ever, this is not pos­sible because the mem­brane blocks elec­trons. And here comes the trick:

We add water between the anode and the mem­brane. For the power source to draw elec­trons at the anode, water molecules (H2O) must split into two hydro­gen atoms (2H) and one oxy­gen atom (O). The two hydro­gen atoms then give up their single elec­tron (2e-) and become two hydro­gen ions (2H+).


(There is always a but in any good story.)

Oxygen fights back

The oxy­gen atom fights back. It doesn’t want to let go of the hydro­gen unless it makes a new friend. Oxy­gen atoms prefer to stick togeth­er in pairs (O2). How­ever, this requires two water molecules to split up vir­tu­ally sim­ul­tan­eously and close to each oth­er, which doesn’t hap­pen very often. So, to speed up the pro­cess, some­thing is needed for the oxy­gen atoms to hold hands with while they look for a mate to merge with.

What do oxy­gen atoms like as much as them­selves? Met­al. Oxy­gen loves met­al so much that it forms an oxide with it. If the met­al is iron or steel, we call this oxide rust. And trust me, rust is not desir­able in a PEM electrolyzer.

Iridium enters the scene

So, are there any metals that attract oxy­gen without per­ish­ing in the relationship?

Yes, there are. They are col­lect­ively called plat­in­um-group metals: rutheni­um, rho­di­um, pal­la­di­um, osmi­um, iridi­um, and plat­in­um. And the most res­ist­ant of them all is…

Drum­roll, please.

Yes, you guessed it: Iridium.

The reaction

Iridi­um is a safe place for oxy­gen atoms to land while wait­ing for a new part­ner. When two oxy­gen atoms land next to each oth­er, they let go of the iridi­um and com­bine to become oxy­gen (O2).

Thus, we have the fol­low­ing reac­tion on the anode side in a PEM electrolyzer:

2H2O → 4H+ + 4e- + O2

On the oth­er side of the mem­brane, the cath­ode spouts out elec­trons. The hydro­gen ions (H+) are attrac­ted to these excess elec­trons, so they migrate through the mem­brane. (Remem­ber that a hydro­gen atom is just a pro­ton with an elec­tron, so when the elec­tron is gone, the hydro­gen ion is a pro­ton, which can pass through the membrane.)

Once on the oth­er side, each hydro­gen ion joins with an elec­tron to become a hydro­gen atom. Then, the hydro­gen atoms join togeth­er in pairs to form hydro­gen gas (H2).

And just like that, we have pro­duced hydro­gen gas from just water and electricity.

Simple, huh?

The challenge

Of course, it’s not that simple.

Water has to flow around the iridi­um for the reac­tion to take place. The iridi­um should be in con­tact with the mem­brane to allow the hydro­gen ions to cross over to the oth­er side. The iridi­um must be elec­tric­ally con­nec­ted to a power source to pull the elec­trons in. And the oxy­gen gas has to be dis­sip­ated. All this hap­pens only on the anode side of the membrane.

On the cath­ode side, the mem­brane must be in con­tact with the cath­ode so that the hydro­gen ions can com­bine with elec­trons to form hydro­gen atoms, which must then be trans­por­ted away to be utilized.

Anoth­er thing to con­sider is that the more iridi­um in con­tact with the mem­brane, the more water can be broken down into hydro­gen and oxy­gen. How­ever, you can’t just cov­er one side of the mem­brane with iridi­um because it would block the hydro­gen ions from passing through the membrane.

The stack

The solu­tion is to build a stack called Mem­brane Elec­trode Assembly (MEA). Ellinor Ehrn­berg describes how a typ­ic­al MEA is built:

“Small grains of iridi­um are mixed in a solvent, and the res­ult is used as ‘ink’ to make screen prints on the anode side of the mem­brane. The res­ult is called a Cata­lyst Coated Mem­brane.

“On top of the cata­lyst coat­ing, a lay­er of elec­tric­ally con­duct­ive and por­ous mater­i­al is added to con­duct elec­tri­city and water to the mem­brane and allow oxy­gen to escape. This is called the por­ous trans­port lay­er or PTL. Anoth­er PTL is added on the oth­er side of the mem­brane to allow hydro­gen to escape.”

“Finally, the whole thing is firmly pressed togeth­er to ensure that the mem­brane, the iridi­um, and the por­ous trans­port lay­er come into con­tact with each oth­er,” Ellinor Ehrn­berg con­cludes the explanation.

This sounds like an eleg­ant solu­tion. But there is a catch.

Waste of iridium

“The sur­face of the por­ous trans­port lay­er is… por­ous. It is not smooth. When everything is pressed togeth­er to make con­tact, its rough­ness can dam­age the cata­lyst coat­ing, break­ing the con­duct­ive path neces­sary for elec­tron flow,” explains Ellinor Ehrnberg.

The solu­tion is to apply sev­er­al lay­ers of cata­lyst coat­ing on top of each oth­er. But this is a sig­ni­fic­ant waste of iridi­um because most grains of iridi­um end up inside the lay­er. They don’t come into con­tact with water and the mem­brane and don’t con­trib­ute to hydro­gen production.

This would not be a prob­lem if iridi­um were not so rare.

Extremely rare

Iridi­um is extremely rare; only sev­en to eight tons can be extrac­ted annu­ally. This lim­ited avail­ab­il­ity con­trib­utes to the metal’s high cost. As of Octo­ber 2023, iridium’s mar­ket price exceeds USD 160,000 per kilogram.

Each PEM-elec­tro­lyz­er doesn’t use much iridi­um. Cata­lyst-coated mem­brane uses about two mil­li­grams of iridi­um per square cen­ti­meter (2 mg/​cm2). But it adds up to a lot, and with the rap­idly grow­ing demand, it will soon cause the demand for iridi­um to exceed the supply.

So, some­thing must be done.

The holy grail

Part of the solu­tion is recov­er­ing iridi­um from end-of-life PEM elec­tro­lyz­ers. But that alone is not enough. To meet demand and keep the use of vir­gin iridi­um at an accept­able level, the amount of iridi­um per square cen­ti­meter of the mem­brane must be reduced to one-twen­ti­eth of the cur­rent amount.

That’s why 0.1 mil­li­grams of iridi­um per square cen­ti­meter mem­brane (0.1 mg/​cm2) is the industry’s holy grail.

Smoltek makes it possible

Smol­tek Hydrogen’s tech­no­logy actu­ally makes it pos­sible to get as low as 0.1 mil­li­grams of iridi­um per square cen­ti­meter in the near future.

“We’re not quite there yet, but we’re well on our way,” says Ellinor Ehrn­berg and con­tin­ues: “In the lab, we have reached 0.5 mil­li­grams per square cen­ti­meter and expect to reach 0.1 mil­li­grams soon.”

But how far have oth­ers come? This was the ques­tion that Ellinor Ehrn­berg and her team sought to answer dur­ing the 244th ECS meet­ing in Gothenburg.

The classic route

The most com­mon route is to replace the sol­id grains of iridi­um with sol­id grains of cheap­er mater­i­als and put iridi­um on the out­side, either as a shell or particle by particle.

With this tech­nique, labs can reduce iridi­um to 0.3 mil­li­grams per square cen­ti­meter mem­brane (0.3 mg/​cm2). But that’s about as far as it goes, accord­ing to Ellinor Ehrnberg:

“The coat­ing must still have a cer­tain thick­ness, which inev­it­ably means that grains inside the lay­er can­not come into con­tact. So, even if you have reduced the amount of iridi­um by repla­cing the core with cheap­er mater­i­als, you are still wast­ing a lot.”

Although 0.3 mil­li­grams is a rad­ic­al improve­ment, albeit so far only in labor­at­or­ies, Smol­tek’s goal is still three times more ambi­tious. With Smoltek’s tech­no­logy, pro­du­cing three times as much hydro­gen for the same amount of iridi­um will be possible.

So, while the cur­rent tech­no­logy can be greatly improved, Smol­tek’s tech­no­logy will still have a sig­ni­fic­ant com­pet­it­ive advantage.

Is there no one else who can reach the same low level as Smol­tek? Truth to be told, there is.

The high-performance route

Los Alam­os Nation­al Lab – per­haps best known for the atom­ic bomb – has chosen the same path as Smol­tek. Instead of try­ing to improve a flawed idea – the Cata­lyst Coated Mem­brane – both have chosen a com­pletely dif­fer­ent route.

The idea is to cre­ate fibers that run like spikes between the por­ous trans­port lay­er and the mem­brane. The fibers are coated with plat­in­um to pro­tect them from the cor­ros­ive envir­on­ment. Nan­o­particles of iridi­um are attached to the out­side of the plat­in­um sur­face of the fibers. In this way, each particle comes into con­tact with water and con­trib­utes to hydro­gen production.

“They have chosen the same path as us, and for me, that proves we are doing the right thing,” says Ellinor Ehrnberg.

Oh dear. Same solu­tion. That can­not be good for Smol­tek Hydrogen.

Different solutions

“There are cru­cial dif­fer­ences,” assures Ellinor Ehrnberg.

Unlike Smol­tek, Los Alam­os Nation­al Labor­at­ory has chosen to cre­ate the fibers in the same mater­i­al as the mem­brane. These fibers are “pulled out” of the mem­brane and bent at the top so that they touch each oth­er. This cre­ates two prob­lems, accord­ing to Ellinor Ehrnberg:

“First, when a mem­brane elec­trode assembly is man­u­fac­tured, the por­ous trans­port lay­er is pressed with great force against the mem­brane. That’s no prob­lem for Smoltek’s strong car­bon nan­ofibers, but it may be chal­len­ging for Los Alam­os fibers. They are made of nafion, a soft poly­mer that read­ily bends under pressure.”

“Second, Los Alam­os fibers must be bent at the tips to make elec­tric­al con­tact, which can impair water flow and oxy­gen dissipation.”

Key competitive advantage

But per­haps the most import­ant com­pet­it­ive advant­age, accord­ing to Ellinor Ehrn­berg, is Smoltek’s head start.

“My team is work­ing in two par­al­lel tracks. We are refin­ing our tech­no­logy to achieve 0.1 mil­li­grams of iridi­um per square cen­ti­meter. And at the same time, we are devel­op­ing an indus­tri­al man­u­fac­tur­ing pro­cess. Our plan is to com­bine the two tracks in a pilot plant to be com­pleted in 2025.”

Los Alam­os Nation­al Labor­at­ory is not work­ing on indus­tri­al­iz­a­tion at all. On a dir­ect ques­tion from an employ­ee at Smol­tek, Jac­ob S. Spende­low, who presen­ted the res­ults from Los Alam­os Nation­al Labor­at­ory dur­ing the ECS 244th meet­ing, answered that they “wish” for a part­ner to indus­tri­al­ize the technology.


To sum­mar­ize, Ellinor Ehrn­berg is delighted with what she and her team learned dur­ing the ECS 244th meet­ing in Gothenburg.

She feels con­fid­ent that Smol­tek has chosen the right path. The clas­sic route – adding lay­er upon lay­er of iridi­um grains – will always waste the scarce met­al. To reach the holy grail – 0.1 mil­li­grams of iridi­um per square cen­ti­meter (0.1 mg/​cm2) – man­u­fac­tur­ers must fol­low Smol­tek’s path.

Although oth­ers are look­ing at the same path, Ellinor Ehrn­berg is con­vinced that Smol­tek is ahead of the game.

“We don’t know of any com­pany that has come as far as us,” she con­fid­ently assures. “Oth­ers struggle with redu­cing iridi­um, obtain­ing suf­fi­cient life­time, or scal­ing up.”What are your thoughts on Smol­tek Hydro­gen­’s future? Leave your com­ments on LinkedIn.

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