What makes it a great choice for hydrogen R&D?

• The most flexible electrolyser stack product for research on the market
• 25 cm2 active area
• With or without flow field
• Up to 9 cells with electrodes
• Any electrode thickness down to almost 0 mm
• Individual cell voltages can be measured directly on bipolar plate

Repeating cell structure

The stack can be configured wiht up to 9 cells. Each cell is build up around a membrane or separator with an electrode on each side and a bipolar plate.

The electrodes (5×5 cm) are placed within a set of gaskets, consisiting of cover gaskets and a central flow-field gaskets, specifically designed for the X-Stack for best performance. Hence for each cell, 4 cover gaskets and 2 flow-field gaskets are needed. The combined thickness of the cover gaskets and flow-field gasket on each side, should match the desired compressed thickness of the electrodes.

Temperature control

The latest version of the X-Cell (launched April 2025) includes an integrated temperature measurement system. A metal sensor block is embedded in the PEEK flow body and pressed against the current collector to enable accurate temperature readings. It supports common thermometer and thermocouple sizes (3 mm, 4 mm, and 1/8″).

Temperature Control Unit

This system can be used in combination with a dedicated temperature control setup based on a flow heat exchanger principle. To the best of our knowledge, similar products cannot be found by any other companies in the field.

Our solution comes as three different configurations that are based on the same components and can be interchanged. All options are based on a PEEK flow body and aluminum block shown above. The PEEK body contains one (variant 1) or two separate (variant 2) flow chambers for heating/cooling one or two independent liquids, respectively. The liquids in the experimental setup are circulated through the PEEK flow body and placed up against an aluminium heating/cooling plate, whereby heat is transferred to or from the liquids in the PEEK flow body. The aluminium plate is separated from the liquids by a thin PTFE sheet, whereby corrosive/oxidative solutions also can be heated without corroding the aluminium plate.

Besides the possibility for placing the aluminium block on a heating plate, it also comes with holes for heat cartridges, cooling liquids and thermometers.

Variants

X-Stack with flat surface

The design of the X-cell stack is a result of almost 10 years of know-how in the field of flow redox chemistry and maybe the only research stack product on the market. It was developed for testing/optimisation of components (electrode/membranes/bipolar plates), testing of stack properties, upscaling and demonstration. It can be tested with up to nine cells, electrodes must be at least 1 mm thick, but can be any material. Different electrode compressions can be obtained by different spacer thicknesses. Stack can be is supplied with different bipolar plate materials (Nickel, Titanium, Stainless Steel). It was designed with focus on trade-of between minimizing pressure inside cell and keeping shunt currents low.

X-Stack with flow field

The X-stack FF is an R&D stack similar to the X-stack Flat, the only difference is that X-stack FF comes with bipolar plates that have interdigitated flow fields which allows testing of very thin electrodes (for the X-stack Flat we recommend not to use electrodes thinner than approximately 1 mm). It was developed for testing/optimisation of components (electrode/membranes/bipolar plates), testing of stack properties, upscaling and demonstration. It can be tested with up to nine cells.

Accessories

• Inline pressure unit
• Flow-through electrode holder
• UV/VIS fiber optical flow cell
• Open circuited voltage cell

Application Areas

The X-Stack supports a broad range of electrochemical processes, including:

• Alkaline water electrolysis
• PEM and AEM water electrolysis
• CO₂ electrolysis and electrochemical reduction
• Electrochemical metal recovery and refining
• Desalination and ion removal
• Organic electrosynthesis and non-aqueous systems
• Redox flow battery testing
• General-purpose electrochemical flow testing

Technical Specifications

• Active Area: 25 cm2 (5 cm x 5 cm)
• Bipolar plates: Standard materials for current collectors: nickel, stainless steel, titanium, copper, plantinum-coated titanium, gold-coated titanium
• Electrode thicknesses > 0 mm
• Flowbody made of PEEK or PTFE
• With or without flow field area Stainless steel endplates
• Swagelok fittings for tight connecting to 1/4” or 1/8” tubing
• Comes ready-to-use as on pictures but without membranes and electrodes

We accomodate custom requests for active area sizes, materials for current collectors, and tubing dimension. For this, submit a request on www.redox-flow.com.