Redox Flow Battery Test Cell

Redox Flow Battery Test Stack

Redox Flow Battery (RFB) lab cell for test of vanadium flow batteries or other battery chemistries.


Fast assembly

Optimized flow field pattern

Redox solution is not in contact with metal parts

Variable electrode thickness

Carbon felt electrodes option

Flow Fields can be custom made

This flow cell is intended for redox flow battery research and development. Alternatively it can be used an electrochemical flow cell for test of membrane properties or similar. It comes with either 6.25 cm2 or 25 cm2 active area. The design has focused on ease of use and fast assembly/disassembly making it ideal for research applications. The cell consists of two mirrored half-cells separated by a membrane. Through each half-cell electrolyte solution is circulated and the electrochemical reaction takes place in electrodes pressed against both sides of the membrane. The current passes through the current collectors and graphite blocks. There is no contact between metal parts and electrolyte solutions. The interdigitated flow field in the cell is optimized for RFB applications with minimum internal resistance. For specialized flow fields or carbon felt electrodes and other active areas please contact us.

One of the unique features is that the A-cell also can be connected the Differential Pressure Unit that will allow measurement of pressure loss over cell. Also it can be connected with Flow Through Electrode Holder for e.g. inline monitoring of pH, ORP, reference, conductivity or any other electrode. Signals from pressure sensors and electrodes can be recorded in AUX Unit, which combined form an extremely powerful tool for both optimisation studies or flow battery chemistry development.


If you want custom made flow fields please send a drawing with the exact dimensions of the flow field, including depth. Also flow inlets from manifold can be custom made. The custom made area can be either 5 cm x 5 cm or 2.5 cm x 2.5 cm.


Active Area: 6.25cm2 or 25cm2

Flow Field Pattern: 1mm Interdigitated or carbon felt electrode without flow field

Stainless steel End Plates

Gold plated cobber current collectors

Machined graphite or titanium (Grade 1) half cell – other materials on request

Swagelok fittings for tight connecting to 1/8” tubing (1/4″ or other fitting sizes on request)


Materials: PFTE (Teflon), PFA (Similar to Teflon) – other materials on request

Thicknesses: 0.1 – 1.5 mm

Weight: 3.9 kg

Flow battery stack with 25 cm2 active area per cell


Maybe the only flow battery stack product for research on the market

25 cm2 active area – other areas are available on request

Up to 9 cells with electrodes > 1 mm

Individual cell voltages can be measured directly on bipolar plate material

The design of the S-cell stack is a result of almost 10 years of know-how in the field of flow battery test cells 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. I can be tested with any number of cells between 1 and 9, electrodes must be at least 1 mm thick, but can be used for any type of electrode material. Different electrode compressions can be obtained by different spacer thicknesses. Stack is supplied with hard bipolar plate materials. Design has been with focus on trade-of between minimizing pressure inside cell and keeping shunt currents low.

Some of the unique features of the S-cell Stack are

Any number of cells between 1 and 9

Any electrode thickness > 1 mm

Individual cell voltages can be measured on the bipolar plates

The electrolyte is only in contact with flow block (graphite), spacers (PTFE, Viton or EPDM), O-ring (Viton/EPDM), bipolar plate, electrode and membrane. The S-cell is intended for optimisation studies, but can also be used a normal flow battery test cell like the A-cell.


Active Area: 25cm2 (5 cm x 5 cm) – for other dimension, please make a request

Only works with electrodes > 1 mm

Body made out of Graphite – for Titanium or other materials, please make a request

Stainless steel end plates

Gold plated cobber current collectors

Swagelok fittings for tight connecting to  1/8” tubing – for other tube dimensions, please make a request

Gaskets: See materials variations and thicknesses at Gasket/Spacers

Comes ready-to-use as on pictures but without membranes and electrodes

Top-performance – With SGL carbon felt and FS950 membrane, polarisation curve gives ASR of 0.8 Ωcm2 per cell – performance is not limited by cell design but limited by electrodes/membranes




  • Scientific publications :-

    • Østedgaard-Munck, David Nicolas, et al. “Membrane-based electrokinetic energy conversion.” Materials today energy 5 (2017): 118-125.
    • Østedgaard-Munck, David Nicolas, et al. “Data on flow cell optimization for membrane-based electrokinetic energy conversion.” Data in brief 15 (2017): 1-11.
    • Østedgaard-Munck, David Nicolas, et al. “Steady state and dynamic response of voltage-operated membrane gates.” Membranes 9.3 (2019): 34.
    • Østedgaard-Munck, David Nicolas, et al. “Direct Measurements of Electroviscous Phenomena in Nafion Membranes.” Membranes 10.11 (2020): 304.
    • Khataee, Amirreza, et al. “Differential pH as a method for increasing cell potential in organic aqueous flow batteries.” Journal of Materials Chemistry A 5.41 (2017): 21875-21882.
    • Merino-Garcia, Ivan, et al. “Characterization of poly (Acrylic) acid-modified heterogenous anion exchange membranes with improved monovalent permselectivity for RED.” Membranes 10.6 (2020): 134.
    • Bae, Dowon, et al. “Unravelling the practical solar charging performance limits of redox flow batteries based on a single photon device system.” Sustainable Energy & Fuels 3.9 (2019): 2399-2408.
    • Clemente, Alejandro, et al. “Online state of charge estimation for a vanadium redox flow battery with unequal flow rates.” Journal of Energy Storage 60 (2023): 106503.

Electrolyser cells


Photoelectrochemical cells

X-Cell – Electrolyser Test Cell

3 cm x 3 cm electrochemical flow cell intended for research in alkaline electrolysis but it can be used for any type of electrolysis e.g. CO2 reduction. Due to the many materials combinations possibilities are many.

Fast assembly
Variable electrode thickness
Many materials options
Can be used as a general electrochemical flow cell

DESCRIPTION: The electrochemical flow cell for alkaline electrolysis consist of half cells made out PEEK or Titanium (Grade 1).

The PEEK version is intended for use with a bipolar plate (e.g. nickel or titanium) with any thickness >0.1-0.2 mm. A set of nickel bipolar plates/current collectors are coming with the cell, but they can be changed with own made materials. The Titanium version are intended for use where the electrolyser material/electrode is in direct contact with the half-cell material. Nonetheless, it can also be used with bipolar plates/current collectors. Depending on the configuration the cell voltage can be measured either on half cell block or bipolar plate material.


Active Area: 3 cm x 3 cm and 5 cm x 5 cm – for other active areas please make an inquiry
Electrode thickness down to 0.1-0.2 mm (determined by gasket/spacer thickness and flow rate)
Half cells machined in Titanium or PEEK
Swagelok fittings for tight connecting to 1/8” tubing
Gaskets/Spacers: PTFE, EPDM or VITON

Ion exchange membranes for flow batteries. Fumatech anion exchange and Fumatech cation exchange membranes are available.

Precision cut with all holes to your specific cell (A-cell, S-cell or X-cell)
Size about 10.5 cm x 10.5 cm

Typical properties of fumasep membranes used for VRFB
Membrane: FAP-450 / FAPQ-330 / FS-940  / FS-930
Conductor: anionic anionic cationic cationic
Thickness / µm: 50 / 30 / 40  /30
Typical curr. density /mA.cm2: 80-150 / 100-250 / 100-250 / 150-400
Coul. Efficiency / % (1): >98 / >98,5  / >97,5 / >96
Resistance / mOhm.cm2 (2): 650  / 350  / 320  / 190
Capacity retention / % (3): ~ 100 /  ~ 100 /  ~99,9 / ~99,9

Photoelectrochemical (PEC) test cell for photoelectrochemical water splitting or solar charging of flow batteries.

Optimized light penetration through the cell
-The cell is resistant to corrosive liquids
-Possibility for continuous flow of electrolyte
-The two half cells are separated by a membrane

DESCRIPTION: The Photoelectrochemical laboratory test cell consists of a reservoir that holds the electrolyte solution wherein the two electrodes are immersed: the anode and the cathode, where one or both electrodes must be photoactive. This electrolyte container have a transparent window allowing the light to reach the photoactive electrode triggering the electrochemical reactions. The cell can easily be connected to an external electronic source/load. Moreover, this PEC cell reactor allows a continuous electrolyte feeding, besides having a great flexibility for hosting the electrodes.

-Active Area: 25cm2 – 100cm2
– PEC Cell Size: 22cm x 18cm
– Cell Weight: 4 kg
-Operation pH Range: 1-14
– Temperature Operation range: 5C-80C
– Power Radiation: < 3 sun


For any inquiries please email