Eindhoven-based SparkNano have developed solutions using Spatial Atomic Layer Deposition (ALD) nanotechnology to improve process and product efficiency across the electrolysis, fuel cell, battery and solar cell markets. We sat down with Business Development Manager Alexander Bouman to learn more about their work.

With clean hydrogen gaining significant political and business momentum, there is a spotlight on developing and scaling technologies which can bring down costs, reduce the usage of scarce materials and allow widespread use in difficult-to-abate sectors. Such a development provides immense value to the industry and addresses long-standing bottleneck problems that have hindered the full realisation of clean hydrogen’s potential.

Proton exchange membrane (PEM) electrolysis currently represents a significant share of the green hydrogen market, and the value of the PEM market is set to grow at a compound annual growth rate (CAGR) of over 24% between 2023 and 2032, according to Global Market Insights. PEM is favourable for its high efficiency, compact design, fast response, and operation under lower temperatures, amongst other benefits. However, its Achilles heel is reliance on iridium as a catalyst, an extremely rare and expensive (2.5 times more than gold) element whose global resource is dwindling.

SparkNano’s Spatial Atomic Layer Deposition (ALD) technology offers a potential solution to this problem, with the deposition of a Spatial ALD IrO2 catalyst reducing the ‘iridium loading’ (mg of iridium per square centimetre) by a factor of 40 or more. The catalytic layer of iridium oxide or platinum is applied on the porous transport layer (PTL) or gas diffusion layer (GDL) of the electrolyser, with the minimum amount of material used to ensure sufficient catalytic reactions whilst significantly reducing costs.

As Bouman identifies, increasing demand for iridium as a result of rapidly upscaling PEM electrolysis outweighs what can be supplied on an annual basis. This constitutes a significant barrier to be overcome if the developing hydrogen economy is to become a sustainable, long-term solution for decarbonising difficult-to-abate sectors. To put this in perspective, nowadays PEM electrolysis requires approximately 500g of PGM (platinum group metals) per 1 MW capacity. With Spatial ALD, this amount can be reduced to about 10g per 1 MW.

“If you want to develop a hydrogen economy by 2030, there is a total amount of PEM electrolysis involved and that requires a certain amount of iridium if you do it in a conventional way. When using Spatial ALD, we can reduce this amount by a factor of 40 or more, which means we stay within the limitations of global iridium supply”.

So, what is Spatial ALD, and how does it work? Atomic Layer Deposition is a deposition method for thin films (typically <100nm) which is based on chemical reactions between two gaseous reactants and a substrate. As Bouman asserts, this is not an obscure technology but an established method which has been used since the late 1990s, and which plays a key role in the production of microelectronics that compose modern computers, tablets and smartphones. It has a number of benefits, such as its atomic-scale control of thickness and uniformity and its high quality, scalable to large sized substrates.

The Spatial ALD difference, therefore: the reactor speeds up the process time by spatially separating the two important gases from each other, allowing for a dynamic (as opposed to static) process where the substrate moves underneath or on top of these, via an injector “head”. In addition, scaling a Spatial ALD reactor is far more feasible than a traditional batch reactor, which when made larger creates a much longer process that is not economic. By contrast, Spatial ALD offers all the same but much more benefits as traditional ALD and can be scaled whilst maintaining a higher throughput – around 100 times that of traditional batch reactors.

Spatial ALD also brings benefits to the efficiency of manufacturing electrolysers: in contrast to traditional batch reactors, in spatial ALD-enhanced electrolysis the pre-cursor gas only touches the substrate (not the side walls), reducing the wastefulness of the process. Meanwhile, every iridium atom that has not been used can be recycled, regenerated again to produce the precursor gas for a future cycle.

This is a crucial technology unlock for the scaling up of green hydrogen, not only reducing the cost involved in PEM electrolysis plant building (and in turn the cost per kg of hydrogen) but also alleviating the supply chain and resource stress caused by dwindling iridium supplies.

“Because we can extremely accurately apply the amount of materials we deposit, the cost will go down and that is what is needed for the overall target of 1:1:1: in one decade one dollar per one kg of generated green hydrogen.”

In addition, employing Spatial ALD technology has benefits for electrolyser lifespans, given that the porous structure is fully coated and as such protected against harsh conditions in the membrane electrode assembly (MEA).

Spatial ALD is a versatile technology, and SparkNano also have a presence in the battery and solar cell markets. In the battery space, the application of the technology is different, focusing on passivation – by depositing thin layers of aluminium oxide, titanium oxide and many other alloys – to prevent the degradation of electrodes and electrolytes, which result in short lifetimes.

Across each of its three key markets, SparkNano offers both laboratory and production scale equipment. Its Labline series is a versatile R&D tool which allows experimentation to determine factors such as the right process conditions (e.g. temperature, gas flow, specific materials to be deposited) for various applications.

The Vellum series is a sheet-to-sheet mass production tool, with a sheet moving underneath the injector, while by contrast, the Omega series works ‘roll-to-roll’, with a roll going around a rotor to achieve the same function.

These products are still new innovations: established in 2018 in Eindhoven, SparkNano is a spinoff of the Netherlands Organisation for Applied Scientific Research (TNO), and celebrated five years of operations recently.

SparkNano is growing rapidly, with 17 employees and supported by a number of high-profile partners such as Air Liquide and VDL Group manufacturers.

At present, Bouman asserts that there are as many as 35-40 people working across different companies to develop SparkNano equipment. Meanwhile, with ambitions to play a pivotal role in the developing hydrogen and battery markets, the organisation is already in conversation with a number of large PEM electrolyser and lithium-ion battery companies.