The journey towards affordable, large-scale green hydrogen production is linked to the continuous innovation of water electrolyzer stack components. As the heart of the electrolyzer, the stack’s efficiency, durability, and cost are directly shaped by the materials and design of its parts. Advancements in these components are therefore critical to driving down the levelized cost of hydrogen. Innovations are occurring across all key areas, including membranes, electrodes, membrane electrode assemblies (MEAs), bipolar plates, and transport layers.
Key innovation focuses for electrolyzer components (PEM electrolyzer shown as an example). Source: IDTechEx
Thinner, stronger separators are key to balancing performance and durability
While the diaphragms in AELs, membranes in PEM and AEM electrolyzers, and electrolytes in SOECs differ in materials and structure, the fundamental innovation goals are similar. Each separator must strike a delicate balance: lowering electrical resistance while maintaining excellent durability and preventing hydrogen gas from crossing over. To achieve this, diaphragms and ion-exchange membranes are becoming thinner, incorporating reinforcement layers and benefiting from improved manufacturing processes that offer greater control over porosity.
Advanced electrodes and MEAs aim for higher activity with fewer precious metals
The primary objective for all electrode types is to maximize the active surface area for reactions while using more effective catalysts and minimizing the use of precious metals. For instance, next-generation AEL electrodes are focusing on nickel foams with advanced nickel-based catalytic coatings that create a 3D reaction surface. A key priority for PEM electrolyzers is reducing the amount of iridium needed at the anode through novel catalyst development. For both PEM and SOEC technologies, improving the electrode structure through innovations in membrane electrode assembly (MEA) manufacturing is also a critical focus. The AEM electrolyzer space is less standardized, with OEMs still experimenting with various cell architectures.
Cost reduction is the focus for bipolar plate manufacturing and coatings
Bipolar plate manufacturing has benefited significantly from innovations in the PEM fuel cell industry. Learnings from streamlined, high-precision, automated roll-to-roll production processes are now being transferred to electrolyzer manufacturing, as the fundamental processes are very similar. In addition to conventional stamping and hydroforming, some companies have developed alternative methods, most notably photochemical etching, to further enhance the precision for intricate flow channel designs.
Coatings for bipolar plates represent a major area of innovation, particularly for PEM electrolyzers, which require gold on the cathode side and platinum on the anode side. As conventional plating methods can be wasteful, many companies are now offering advanced vapor deposition techniques to apply these precious metals more efficiently, reducing consumption and cost.
Transport layers with improving flow and stability
Gas diffusion layers (GDLs) and porous transport layers (PTLs) have become essential components in AEL, AEMEL, and PEMEL systems. While AELs have only recently started adopting advanced PTLs like nickel foams, PEM electrolyzers have long relied on carbon paper GDLs and titanium felt PTLs. Key innovation focuses include optimizing mechanical properties for better long-term stability within the stack, creating graded porosity profiles for improved fluid flow, reducing overall thickness, and lowering the need for precious metal coatings on metal PTLs.
Furthermore, AEL and AEMEL electrolyzer OEMs are experimenting with novel porous transport electrode (PTE) concepts, which combine the electrode and the PTL into a single component. This integrated design has already demonstrated increases in stack efficiency, suggesting that future stack designs may increasingly adopt this innovative approach.
Summary & outlook: a multi-billion dollar component market fueled by continuous innovation
