Is Smoltek Hydrogen ahead of the game?

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⁺).

But…

(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.

Conclusion

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.