Liquid is only in contact with the PEEK flow body, gaskets (PTFE, Viton or EPDM) and optical window (UV/VIS transparent quartz glass). Connections to the cell is with 1/4-28 UNF threads and will allow many tube diameters. As standard the cell comes fittings for 1/8 OD hard tubing.

TECHNICAL SPECIFICATIONS:

• SMA 905 fiber optical connection
• Optical path length from 0.05 mm to > 1 cm
• Flow rates > 100 ml/min with minimal pressure loss in the cell (internal hydraulic bypass)
• Full/large pH range – All parts are in corrosion resistant materials (PEEK flow body, PTFE, Viton or EPDM gaskets). Only exception is the optical quartz window which can corrode after prolonged use in glass corrosive media (typically hydroflouric acid and strongly alkaline solutions (e.g. 6 M KOH) and at elevated temperatures. Cell is supplied with replacement optical quartz windows.
• Fittings for tight connecting to 1/8” tubing – For other tube dimensions please make a request
• Gaskets/Spacers Materials: PTFE, EPDM or VITON (comes as standard with spacers for optical lengths from 0.05 mm to 10 mm)

PERFORMANCE

Graph below shows absorbance measured in UV/VIS cell with 0.1 mm optical length on ‘yellow fruit color’ diluted with 1:10.

OTHER RESOURCES

• TO BE UPDATED

Precision cut (either 2.5 cm x 2.5 cm OR 5.0 cm x 5.0 cm) or in sheets of 20cm x 30cm.  Variants are shown below

The poresize is given in Pores per inch, the porosity is 1 minus the ratio between the apparent density of the foam  and theoretical density of nickel. Both the area weight and porosity may vary.

This X-cell has three compartment and some of the unique features are

• Variable compartment/electrode thickness – it is determined by the gaskets
• Can be supplied with current collectors that have interdigitated flow field or ‘flat surface’
• Material choices are large and with right selection it can fit almost any chemistry

This cell is a variant of the X-cell, the main difference being additional ports that allows a third middle chamber in between the anode/cathode chambers/half cells. The middle chamber is separated by membranes on each side. The left figure below is a schematic overview of the working principle, while the right photo show the cell with the inlet/outlets.  The additional ports on the back of the cells are not used and are blocked. All chambers/half cells have variable thicknesses and are determined by the gaskets used.

GASKETS & ELECTRODE THICKNESS: Due to the many variations, cells are sold without gaskets that has needs to be ordered individually and is described below.

Flat current collectors: The main components of this configuration is shown in the image below – (Click on picture to get higher resolution)

Cover/Spacer gaskets – Here one type is needed  (shown below)

Flow field gaskets – Here two different flow field gaskets are needed (shown below). One is for the anode/cathode chambers while the other is for the middle chamber.

GENERAL DESCRIPTION

The cell has been developed for many applications including Electrodialysis, Alkaline Fuel Cells, Electrochemical CO2 reduction etc.  This is also reflected in the many standard material options that are available for the cell.

Besides the current collectors and electrodes the electrolyte will only be in contact with corrosion resistant polymers which is important to ensure that e.g. electrodes/catalysts are not poisoned from dissolution of e.g. metals in the cell. Also it can be operated in the full pH range (depending on materials choices) and to elevated temperatures (95°C).

TECHNICAL SPECIFICATIONS:

• Active Area: 2.5cm x 2.5cm and 5cm x 5cm – for other active areas please make an inquiry
• Current collectors with and without flow field – any electrode thicknesses
• Main flow body is machined in highly corrosion resistant PEEK
• Can be operated up to 95°C
• Full pH range – depending on current collector and gasket materials
• Standard materials for current collectors: Nickel, Titanium, Stainless Steel and Copper – for other materials please make an inquiry, we can do many
• Swagelok fittings for tight connecting to 1/8” tubing – For other tubing dimensions please make a request
• Gaskets/Spacers Materials: PTFE, EPDM or VITON

OTHER RESOURCES

• Reference electrode measurements inside cell through Luggin Cappilary type connection – as reference electrodes are placed outside cell, the cell can be operated at high temperatures without damaging the reference electrode
• The cell comes with four additional ports for 1/8” OD tubing (for other dimensions, please make an inquiry)
• Two of the ports creates galvanic connections to the membrane/separator that enables reference electrode measurements similar to standard 3-electrode setup where the reference electrode is placed in between the working and counter electrode
• The two other ports create galvanic connections with the inlet (or outlet) just before the electrodes in cell for more specialized reference electrode measurements

This cell is a member of X-cells with additional ports (LINK) where the additional ports can be used for different purposes. I.e. if a X-cell with additional ports has been aquired it can be changed into the types only by buying the gaskets for that specific application. For a general description of the X-cell, please see https://redox-flow.com/shop/x-cell/. The X-cell with ports can be made for cells with ‘flat surface’ and interdigitated flow field current collectors. However, below it is only described with flat surface below.

GASKETS & ELECTRODE THICKNESS: Due to the many variations, cells are sold without gaskets that has needs to be ordered individually and is described below.

Flat current collectors: The main components of this configuration is shown in the image below – (Click on picture to get higher resolution)

Cover/Spacer gaskets – Here two different cover/spacer gaskets are needed (shown below)

Flow field gaskets – Here two different flow field gaskets are needed (shown below) – note that they are similar but are not symmetric (like almost other Redox-Flow gaskets)

Membrane/Separator gasket – Optional, only needed for porous separators to prevent leaking out through the side of the porous separator.

GENERAL DESCRIPTION

The cell has been developed for Alkaline water electrolysis, Anion exchange membrane water electrolysis (AEMWE), PEM electrolysis and CO2 electrolysis, but can be used as a general electrochemical flow cell e.g. fuel cell, non-aqueous electrochemical systems etc. This is also reflected in the many standard material options that are available for the cell.

Besides the current collectors and electrodes the electrolyte will only be in contact with corrosion resistant polymers which is important to ensure that e.g. electrodes/catalysts are not poisoned from dissolution of e.g. metals in the cell. Also it can be operated in the full pH range (depending on materials choices) and to elevated temperatures (95°C).

This cell is a variant of the X-cell, the main difference being additional ports for a (reference) electrode that is coupled, to measure on the separator/membrane, through a Luggin capillary type setup. The figure below is a schematic overview of the working principle. Red parts are reference electrodes and the hydraulic circuits of these, while blue parts are the X-cell. The reference electrodes at the top can be connected through a T piece (and are not in scope in this manual).

The main difference between the standard X-cell and the one is highlighted by the blue shaded round area. Here additional ports on each side of the cell are included. This enables a hydraulic connection to (i) the separator/membrane which can be used for a reference electrode measurement (Luggin capillary type) and (ii) electrode inlets on both the cathode and anode side. To ensure a unbroken galvanic connection between the separator/membrane there are ports on each side. One is used for a reservior (rigth side) while the left side is connected to the reference electrode (e.g. through the Redox-flow ‘Flow Through Electrode Holders’. The galvanic connection is obtained by sucking electrolyte through the ports with a syringe (see photos below)

Overview of the function of the different gaskets and holes is shown below.

The cell works excellent together with our Flow Through Electrode Holder (see image below)

PERFORMANCE DATA

Figure below shows the polarization curve for a setup with nickel foam electrodes, 6 M KOH measured at room temperature. Here an area specific resistance of about 1.1 Ωcm2 is found and the activation voltage is about 2.2 V. This is similar to the values found in litterature recorded under similar conditions, thus the ‘relatively’ poor performance is because of the low temperature and that the electrodes are untreated (no catalysts). Thus much better performance can be obtained with higher temperature, thinner separator and treated electrodes.

The right side shows the overpotentials measured through the four ports in the cell in a Luggin capillary configuration that is the same as in the figure above with a Hg/HgO reference electrode for each of the three luggin capillaries. The graph shows the maximum and minimum overpotentials, that are measured versus the membrane and in the liquid just before entering the electrodes, respectively. All potentials are not IR compensated and the definitions follows the ones in this paper. Besides the fact that the electrodes are outside the cell and the cell thereby can be operated at high temperature without destroying the reference electrodes, another unique feature is that luggin capillares just before the electrodes are placed within a few mm of the electrodes. This has the positive effect that the IR compensation becomes very small or even close to negligible under many circumstances.

TECHNICAL SPECIFICATIONS:

• Active Area: 2.5cm x 2.5cm and 5cm x 5cm – for other active areas please make an inquiry
• Current collectors with and without flow field – any electrode thicknesses
• Main flow body is machined in highly corrosion resistant PEEK
• Can be operated up to 95°C
• Full pH range – depending on current collector and gasket materials
• Standard materials for current collectors: Nickel, Titanium, Stainless Steel and Copper – for other materials please make an inquiry, we can do many
• Swagelok fittings for tight connecting to 1/8” tubing – For other tubing dimensions please make a request
• Gaskets/Spacers Materials: PTFE, EPDM or VITON

OTHER RESOURCES

• Assembly manual

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

• Up to 9 cells in the stack
• Any electrode thickness > 1 mm
• Individual cell voltages can be measured on the bipolar plates

The electrolyte is only in contact with flow body (PEEK), gaskets (PTFE, Viton or EPDM), O-ring (Viton/EPDM), metal bipolar plate, electrode and membrane. The X-cell is intended for general electrolysers purposes ranging from acidic to alkaline environment.

TECHNICAL SPECIFICATIONS:

• Active Area: 25cm2 (5 cm x 5 cm) – for other dimensions, please make a request
• Bipolar plates either Nickel, Titanium or Stainless Steel
• Electrode thicknesses > 1 mm
• Flowbody made in PEEK
• Stainless steel end plates
• Swagelok fittings for tight connecting to  1/8” tubing – for other tube dimensions, please make a request
• Comes ready-to-use as on pictures but without membranes and electrodes

PERFORMANCE DATA

Figure below shows data for the stack in ‘alkaline electrolyser’ mode with 6 cells. I.e. with 6 M KOH and nickel foam electrodes and operated at room temperature. Here an area specific area resistance (ASR) of 1.2 Ωcm² is obtained. This value is similar to the best performance in scientific literature for single cell under similar conditions. Thus performance can be greatly improved by optimised separators, electrode catalysts and higher temperatures. More importantly the figure also shows the faradaic efficiency which increases from about 90 % at 10 mA/cm² to almost 100 % faradaic efficiency >50 mA/cm² .  This excellent performance is a result of carefully designed flow field channels in the stack that minimizes shunt currents between cells. General prediction of shunt currents are extremely difficult, nonetheless if the ASR is improved/minimized this will lead to lower shunt currents and higher faradaic efficiency. Considering that the data shown are for un-optimised electrodes the faradaic efficiency can be considered as a minimum value for this configuration.

Together with the flexibility and versatility, we consider our stack as the best platform for testing of stack properties, upscaling and demonstration. We made the platform, you optimise it.

Figure below shows individual cell voltages when the stack is operated with 40 mA/cm²  and it is seen that the end cells have slightly higher voltages than the central cells. It is anticipated that this trend is related to shunt currents that are higher for the central cells.

OTHER RESOURCES

• TO BE UPDATED

The Separator Sealing Gasket is produced with an open area of 5.7 cm x 5.7 cm area  – see photo belowSINGLE GASKETS & PACKS OF GASKETS: Gasket can be ordered individually, however, we also offer a pack gaskets with a volume discount.

Separator Sealing Gasket Pack

• 2 pieces – 0.1mm PTFE
• 1 piece – 0.25 mm PTFE
• 1 piece  – 0.5 mm PTFE
• 1 piece – 1 mm EPDM

GENERAL: Gaskets are supplied in either PTFE, VITON or EPDM. VITON and EPDM is more flexible and will easily seal the cells, however, the minimum thickness of VITON/EPDM gaskets is 0.5 mm. PTFE gaskets are more rigid but comes in thicknesses down to 0.05 mm. Combination of several (both PTFE and Viton) gaskets can be done to ensure right electrode thickness/compression.

PTFE: Overall most corrosion resistant material and comes with thicknesses down to 0.05 mm. But rigid and less good sealing properties

VITON: Compressible that will make cell sealing easy. Redox-Flow recommends VITON (and PTFE) for Vanadium flow battery applications – please see a chemical compatibility chart of VITON for your specific application

EPDM:Compressible that will make cell sealing easy. Redox-Flow recommends EPDM (and PTFE) for alkaline conditions – please see a chemical compatibility chart of EPDM for your specific application

SINGLE GASKETS & PACKS OF GASKETS (A, S and X cell): Gasket can be ordered individually, however, we also offer packs of Spacer/Cover gaskets with a volume discount. These pack includes gaskets with thicknesses that will allow testing and compression of almost any electrodes thicknesses. Typically the PTFE Thin Pack will be combined with one of the PTFE, VITON or EPDM Thick Packs.

PTFE Thick Pack includes sets (one pair) of

• 1 set – 0.5 mm PTFE
• 1 set – 1.0 mm PTFE
• 1 set – 2.0 mm PTFE

VITON Thick Pack includes sets (one pair) of

• 1 set – 0.5 mm VITON
• 1 set – 1 mm VITON
• 1 set – 2.0 mm VITON

EPDM Thick Pack includes sets (one pair) of

• 1 set – 0.5 mm EPDM
• 1 set – 1 mm EPDM
• 1 set – 2.0 mm EPDM

GENERAL: Gaskets are supplied in either PTFE, VITON or EPDM. VITON and EPDM is more flexible and will easily seal the cells, however, the minimum thickness of VITON/EPDM gaskets is 0.5 mm. PTFE gaskets are more rigid but comes in thicknesses down to 0.05 mm. Combination of several (both PTFE and Viton) gaskets can be done to ensure right electrode thickness/compression.

PTFE: Overall most corrosion resistant material and comes with thicknesses down to 0.05 mm. But rigid and less good sealing properties

VITON: Compressible that will make cell sealing easy. Redox-Flow recommends VITON (and PTFE) for Vanadium flow battery applications – please see a chemical compatibility chart of VITON for your specific application

EPDM:Compressible that will make cell sealing easy. Redox-Flow recommends EPDM (and PTFE) for alkaline conditions – please see a chemical compatibility chart of EPDM for your specific application

All A, S and X-cells share the Spacer/Cover gaskets and are produced with either 2.5 cm x 2.5 cm and 5 cm x 5 cm active area  – see photo belowSINGLE GASKETS & PACKS OF GASKETS (A, S and X cell):

Gasket can be ordered individually, however, we also offer packs of Spacer/Cover gaskets with a volume discount. These pack includes gaskets with thicknesses that will allow testing and compression of almost any electrodes thicknesses. Typically the PTFE Thin Pack will be combined with one the PTFE, VITON or EPDM Thick Packs.

PTFE Thin Pack includes sets (one pair) of

• 2 sets – 0.05mm PTFE
• 2 sets – 0.1 mm PTFE
• 2 set – 0.25 mm PTFE
• 1 set – 0.5 mm PTFE

PTFE Thick Pack includes sets (one pair) of

• 1 set – 0.5 mm PTFE
• 1 set – 1.0 mm PTFE

VITON Thick Pack includes sets (one pair) of

• 1 set – 0.5 mm VITON
• 1 set – 1 mm VITON

EPDM Thick Pack includes sets (one pair) of

• 1 set – 0.5 mm EPDM
• 1 set – 1 mm EPDM

GENERAL: Gaskets are supplied in either PTFE, VITON or EPDM. VITON and EPDM is more flexible and will easily seal the cells, however, the minimum thickness of VITON/EPDM gaskets is 0.5 mm. PTFE gaskets are more rigid but comes in thicknesses down to 0.05 mm. Combination of several (both PTFE and Viton) gaskets can be done to ensure right electrode thickness/compression.

PTFE: Overall most corrosion resistant material and comes with thicknesses down to 0.05 mm. But rigid and less good sealing properties

VITON: Compressible that will make cell sealing easy. Redox-Flow recommends VITON (and PTFE) for Vanadium flow battery applications – please see a chemical compatibility chart of VITON for your specific application

EPDM:Compressible that will make cell sealing easy. Redox-Flow recommends EPDM (and PTFE) for alkaline conditions – – please see a chemical compatibility chart of EPDM for your specific application

DESCRIPTION:  This is a multi-functional cell intended as an add-on to an flow battery test setup with two fundamental assembly/application principles.

Standard OCV cell : In this assembly the cell can be used for measurement of the OCV and individual cathode and anode overpotentials. I.e. this is is an invaluable tool for flow battery research and optimisation. Drawing below explains the working principles.

Left picture below (click for larger view) show the cell voltage, OCV and the cathode/anode over potential during charging/discharging of the vanadium flow battery cell. Right picture shows the same measurements during measurement of polarisation curve. In this picture also the difference between the cell voltage and the sum of the OCV and overpotential has been included and shows that within experimental precision (1-2 mV) of the equipment used the sum of these voltages equals the cell voltage.

OCV cell with internal reference potential : In this configuration the cell has the same capabilities as the standard OCV cell with the only difference that an additional half cell in the setup allows measurement of all potentials relative to a reference potential. Drawing below explains the working principles.

TECHNICAL SPECIFICATIONS:

• OCV cell with fittings for 1/8” OD tubing – for other diameters please make an inquiry
• Electrolyte only gets in contact with graphite materials and corrosion resistant tubing/fittings
• Gaskets/Spacers: PTFE, EPDM or VITON

OTHER RESOURCES

• Assembly Manual

Each unit consists of the following components

• 1 x PP bottle
• 1 x Two port lid + screw cap
• 1 x Peristaltic tubing (0.5 m)
• 1 x 1/8” PTFE tubing (5 m)
• 2 x 60 cm PTFE pipe (OD ø16 mm ID ø13 mm)
• 2 x  Y fitting (including fittings/ferrules etc)
• 2 x Adaptor/Fitting between peristaltic tubing and 1/8” PTFE tubing (includes all fittings, unions, ferrules etc)
• 1 x Gas seperation unit (with all fittings and ferrules) – Gas separation unit can also be bought separately (without all above fittings)

OTHER RESOURCES

• Assembly manual