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.