IM7

The electrochemical workstations IM7c, IM7, and IM7x are Zahner’s flagship potentiostats. They can be customized with numerous options and extensions for a wide range of electrochemical applications.

Zahner products are carefully manufactured, calibrated, and tested to achieve the highest quality standards. The electrochemical workstations and accessories are packed with great care to prevent damage during transport. Upon receiving of the Zahner’s shipment, please inspect the potentiostat and accessories to ensure they are intact. If a product is damaged during shipping, please contact your Zahner’s representative immediately.

Zahner potentiostats can be operated with the Zahner Lab or integrated into applications using an API. Documented libraries are available for both Python and C++. A LINK TO GITHUB WILL BE ADDED WHEN PUBLISHED with examples is available to assist with developing Python and C++ applications.

• Standalone operation with Zahner Lab

• Integration into custom applications

• Multiple extensions are available:

  • Add-on cards for additional signals

  • External potentiostats and loads for higher voltage/current capabilities

  • Active probes for high-impedance measurements or third-party interfaces

Packing List

• Electrochemical workstation (IM7c or IM7 or IM7x)

• Dummycell

• Testbox

• LoZ-cable

  • Twisted cell cable set for low-impedance objects

  • 2 ODU/2x 4mm banana cables (2 m)

  • 4 clips

  • 4 4mm to 2mm adapters

• HiZ-cable

  • Twisted cell cable set for high-impedance objects

  • 2 ODU/2x 2mm banana cables (1 m)

  • 4 clips

• Ethernet cable (3m)

• Mains cable

• Quick installation guide (with Zahner Lab link)

• 3 Zahner Analysis licenses

• Risk assessment document

General Safety Information

Caution

Protect the potentiostat inputs from electrostatic discharge (ESD)! ESD may damage the potentiostat. ESD-related damages are not covered under warranty. Users must discharge themselves of any electrical charge before touching the potentiostat (TIP: use grounded ESD mats).

Please read the risk assessment document before operating the potentiostat.

Zahner’s potentiostats require a 30-minute warm-up time for optimal performance.

Do not connect active devices such as batteries or fuel cells to the power outputs when the potentiostat is switched off! This may damage the potentiostat.

Don’t touch the electrical connections during the operation.

Cables should be as short and thick as possible.

Before installing the instrument, please read this information carefully for your safety and the safety of your system. Throughout this document, we refer to the workstations IM7x, IM7, and IM7c as ECW (ElectroChemical Workstation). When only one specific model is addressed, we refer to it by name explicitly. Only authorized personnel are allowed to open Zahner devices! There are no user-serviceable parts inside. Non-insulated parts under voltage may cause electric shock when touched. Front panels must not be removed while the instrument is connected to the main power source. Before removing a front panel, switch off the device and disconnect it from the main power supply. Extension cards are installed in the extension slots on the right-hand side of the Signal Processing Unit.

Please strictly follow all instructions written on the ECW case, on tags attached to the case, and in the manuals for your safety and the safety of your system. Pay special attention to the following:

Caution

Connect the ECW only to the main power supply shown on the main plug/fuse holder on the back of the instrument cabinet!

If the system will not be used for an extended period, disconnect the main power supply!

The system must be protected from water, other liquids, and humidity above 65%!

Do not operate the instrument at environmental temperatures higher than 40°C!

Never place the system near a heat source!

Always position the system to allow sufficient ventilation through all ventilation openings. Never place the system on a soft surface!

Do not clean the system with harsh chemicals or hard objects!

If communication problems occur, deactivate all power-saving modes (USB, hard disk, screen, etc.) and screen savers on the instrument computer. Also check firewall and network settings!

Do not open the devices. There are no user-serviceable parts inside!

This device consumes, produces, and radiates electrical energy. Improper installation may cause electrical interference with radio transmitters and receivers. Conversely, strong emitters of electrical fields may cause noise and artifacts in instrument measurements.

Electrostatic Discharge

ECWs are highly sensitive instruments capable of measuring currents down to the fA and aA range. For this purpose, they are equipped with high-precision, high-sensitivity inputs. These inputs are well protected against overvoltage. However, this protection can only be implemented to a degree that does not affect input sensitivity.

Under dry conditions, users can become electrostatically charged by rubbing two different materials together, such as shoe soles against floors or trouser fabric against chair covering materials. You can feel, see, and hear the discharge when touching a metallic part. An electrostatic charge on the human body can reach several thousand volts. The instrument inputs cannot be protected from such high voltages. Therefore, users must take care not to be charged when touching input connectors or connected electrode leads. Discharge can be accomplished by touching a grounded metal surface. The best solution is a grounding pad beneath your ECW system that you touch before touching electrode inputs or electrode cables. The pad must be grounded, for example, to the main ground.

Caution

Electrostatic discharge on the ECW inputs can destroy the input amplifiers!

Before touching electrode connectors or electrode cables, ensure that you have discharged yourself by grounding.

Defects caused by electrostatic discharge are not covered by warranty!

Devices under test (DUTs) can remain connected while turning off or restarting the ECW. Additionally, switching the measurement device from the main ECW to external potentiostats (via EPC42) can be done without reconnecting the DUTs.

Potentiostat Active Shielding

The electrode outlets and cables are actively shielded. This means the buffered input signal is applied to the shielding. This minimizes capacitive artifacts caused by the core and shielding of the cables. Therefore, always use the original cables shipped with the workstation and never connect the shielding of an electrode jack to ground or connect different shieldings together. This deactivates the active shielding and may damage the hardware.

Front Panel

Extension Slots

The CPU card is located on the left side of the device. The slots for expansion cards are located in the center. The right area contains the measurement card set of the basic device. The connections for the internal potentiostat are located on the right side.

The main card set and the expansion cards cannot be exchanged between different ECWs, as the cards must be calibrated with each other. If cards are exchanged without calibration data, measurements will fail.

Table 1 Extension Card Slots

ECW	number of extension slots
IM7c	not available
IM7	4
IM7x	9

LED Status Indicators

The three LEDs indicate the status of the power and the processor. The Top LED is the Power LED, and the two lower LEDs indicate the system status.

Table 2 Top Power LED

Top Power LED	Status	Information
off	Power off	ECW main switch turned off
green	Power on	ECW main switch turned on

Table 3 Status LEDs

Upper LED / SYS	Lower LED / User	Status
Blue	Blue	FSBL Production (QSPI)
Blue	White	FSBL Factory (SD)
Blue	Orange	FSBL Recovery
Cyan	Blue	U-Boot Production
Cyan	Orange	U-Boot Recovery
Purple	Purple	Kernel
Red/Blue Blink	Blue/Red Blink	Update
Red	Orange	Update Error
Unchanged	Green	Discovery Server Start
Green	Green	Ready to Connect
White	User Color	Normal Operation - Idle
Orange	User Color	Normal Operation - Job Active
Red	Red	Fatal Error

Potentiostat E/I Probe Connection

The I/E probe connections provide control signals and power supplies for active ballasts in addition to the potentiostat electrode connections. The ODU push-pull connections lock automatically when plugged in and unlock automatically when unplugged. Coded interlocks guarantee a twist-proof application.

Caution

Never attempt to loosen the ODU plugs by turning them. This can loosen the strain relief and possibly damage the individual test leads or device.

E Probe connector

Socket type: ODU Medi-Snap G11MA7-P08LFD0-0050

Table 4 E Probe connector

Pin	Signal	Information
1	not connected
2	RE	reference electrode input
3	RE shield	RE active shield (buffered reference signal)
4	-22 V	negative power supply
5	+22 V	positive power supply
6	WEs shield	WE sense active shield (buffered sense signal)
7	WEs	working electrode sense input
8	GND	power supply ground signal

Corresponding plug connector: ODU Medi-Snap push-pull-connector S11MA7-P08MFD0-5250

I Probe Connector

Socket type: ODU Medi-Snap G11M07-P08LFD0-0020

Table 5 I Probe connector

Pin	Signal	Information
1	CE	counter electrode output
2	CE shield	CE active shield
3	GND	power supply ground (also used as WE shield signal)
4	FRA	analog control signal (FRA-mode)
5	-22 V	negative power supply
6	+22 V	positive power supply
7	DATA	control output for active probes
8	WE	working electrode output

Corresponding plug connector: ODU Medi-Snap push-pull-connector S11M07-P08MFD0-6520

Probes and special cables are available for measuring very high-resistance or very low-resistance objects:

• LoZ-Cable (low-inductance twisted cable set for low-impedance objects)

• HiZ-Cable (shielded cable set for high-impedance measurements)

• FRA-Probe (analog interface for third-party devices for high-power EIS)

• FRA-X (advanced FRA-Probe with independent E/I measurements)

Rear Panel

LAN Connection

Mains Voltage, Fuses and Connection Procedure

To change the input voltage range or replace the two fuses, the fuse holder must be removed. To do this, the fuse nose is bent towards the holder and the holder can be removed from the filter.

The following miniature fuses are required for safe operation:

• Fuses for 115V: 2x 4A T (4A, slow-blow)

• Fuses for 230V: 2x 2A T (2A, slow-blow)

To change the input voltage range, the insert can be pulled out of the fuse holder. The insert must be rotated so that the desired input voltage is visible through the window of the holder when it is reinserted into the fuse holder.

Connection Procedure

1. Connect the ECW and optional devices to the main power supply.

2. Connect the ECW LAN to a free LAN port on the computer or network.

3. Connect optional devices to the ECW, such as external potentiostats or loads with EPC42.

4. Switch on the optional devices.

5. Switch on the ECW.

Caution

The EPC cable may only be plugged in or unplugged when both devices are disconnected from the power supply.

Grounded/Floating Mode

In Grounded Mode, the Working Electrode Shield (WE shield) is connected to the protected earth potential. This provides the best signal-to-noise ratio and is therefore recommended for most applications. In this mode, ensure that your sample is not grounded. Otherwise, you may create a ground loop that adds artifacts to your signal (see image below).

In Floating Mode, no electrode is connected to ground. This allows measurement of grounded samples without creating ground loops.

Floating Mode provides only functional separation of the measurement signals from earth potential to eliminate ground loops. This isolation is permissible up to a maximum potential difference of ±60 V between the internal device ground (WE outer conductor) and earth potential. Higher potential differences can damage the measurement device.

Regardless of the operating mode, the conductive housing of the measurement device remains connected to the protective earth conductor.

Connecting Faraday Cage / DUT Shielding

The 4-mm banana plug (marked in the image below) can be used to extend the grounding of the ECW potentiostat to a Faraday cage. To ground the Faraday cage, connect it with a wire and plug the wire into the 4-mm banana plug.

Cooling Fan

Thermal management of the ECW is ensured by active air cooling of the measurement cards and built-in power supply unit. Air is drawn in from the surroundings at the front base of the device. The device feet ensure sufficient air supply. The fan on the rear panel directs heated air out the back of the device. For this reason, maintain a distance of at least 10 cm from the rear wall to other objects.

Current Ranges and Shunt Resistors

Table 6 Current ranges and shunt resistors

Range index	Shunt [Ohm]	Max. current [A]
		IM7c	IM7	IM7x
0	10m	±2.0	±3.0	±4.0
1	100m	±2.0	±3.0	±4.0
2	1	±600m
3	10	±300m
4	100	±30m
5	1k	±3m
6	10k	±300µ
7	100k	±30µ
8	1M	±3µ
9	10M	±300n
10	100M	±30n
11	1G	±3n

The IM7/c/x electrochemical workstations have a total of 12 different current measurement ranges that are typically distributed decadically over the entire range. Current ranges 0-2 are exceptions, as they are adapted for power loss or compliance maintenance reasons.

Safe Operating Conditions

In this section, the safe operating ranges for the IM7/c/x internal potentiostat are provided. In the tables, the “power loss” is taken as an indicator of safe operating conditions. A higher power loss can lead to damage to the potentiostat.

Caution

Please note that the “power loss” in the potentiostat is not the same as “power output” (= Current x Voltage).

IM7c

IM7 (low compliance mode)

IM7 (high compliance mode)

IM7x (low compliance mode)

IM7x (high compliance mode)

Technical Specifications

IM7c

Table 7 IM7c Specifications

General
Overall Bandwidth	DC - 6 MHz
ADC resolution	32 bit DC		24 bit AC
Harmonic Reject	> 60 dB @ ½ full scale
Potentiostat Modes	potentiostatic, galvanostatic, OCP, ZRA, FRA, off
Cell Connection	2-, 3-, 4-terminal kelvin
Ground Reference	grounded, floating (switchable)
Interface	Gigabit ethernet (GbE)
Memory	40 GB (SSD), SD-card slot (system recovery)
Dimensions (H x W x D) in mm	160 x 255 x 385
Weight	8 kg
Accessories	LoZ-cable set, HiZ-cable set, testbox, dummycell, LAN cable, mains cable, Zahner Analysis licence sheet, safety precautions quickstart installation guide (with Zahner Lab link)
Power Supply	100/115/230 VAC, 50/60 Hz, 180 W
Ambient Temperature	+10 °C to +30 °C
Ambient Humidity	< 60 % without derating
Storage Temperature	-20 °C to +85 °C
Input
Maximum Sampling Rate		900 kHz at up to 2 channels		1.8 MSps total sampling rate
Maximum Input Voltage		±5.5 V ±14 V		5 V range 14 V range
Voltage Resolution		±3.2 nV ±9.6 nV		5 V range, gain 100 14 V range, gain 100
Voltage Accuracy		±100 µV ± 10 ppm of reading ±300 µV ± 30 ppm of reading		5 V range 14 V range
DC Current Resolution		±2 aA		32 bit
DC Current Accuracy		±0.5% of reading ± 0.2% of FS ±0.05% of reading ± 0.02% of FS ±0.5% of reading ± 0.2% of FS ±0.5% of reading ± 125 fA		300 mA … 2 A 3 µA … 300 mA 30 nA … 3 µA < 30 nA
Input Impedance		> 10 TΩ, ±5 pF		typical
Input Leakage Current		< 200 fA 5 pA		typical maximum
Impedance Range		20 µΩ to 100 GΩ		see IM7c accuracy contour plot for detailed information about EIS accuracy and conditions.
Common Mode Rejection		> 86 dB > 66 dB		10 µHz to 100 kHz 100 kHz to 5 MHz
Input Channel Phase-tracking Accuracy		±0.05 deg ±0.125 deg		10 µHz to 100 kHz 100 kHz to 5 MHz
Equivalent Effective Input Noise		1 µV rms, 100 fA rms		1 mHz to 10 Hz
Output Potentiostatic
Controlled Voltage		±5 V ±14 V		5 V range 14 V range
Resolution		±2.5 nV ±7.5 nV		5 V range 14 V range
Accuracy		±250 µV ± 20 ppm of reading ±750 µV ± 60 ppm of reading		5 V range 14 V range
Integral Nonlinearity		typ. 4 ppm, max. 8 ppm typ. 12 ppm, max. 24 ppm		5 V range 14 V range
Compliance Voltage		±14 V
Bandwidth		6 MHz		@ 33 Ω load
IR Compensation		auto AC impedance technique range 0 to 10 MΩ resolution 0.012%
Small Signal Rise Time		150 ns to 200 µs in 5 steps		automatic selection
Slew Rate		15 MV/s
Output Galvanostatic
Controlled Current		±2 A
Current Ranges		±3 nA to ±2 A		in 12 steps
Resolution		±0.2 ppm of FS		32 bit
Accuracy		±0.1% of reading ± 0.04% of FS ±0.4% of reading ± 0.2% of FS		> 3 µA … 300 mA < 3 µA or > 300 mA
Frequency Generator and Analyzer
Frequency Range		10 µHz to 5 MHz
Frequency Accuracy		< 0.0025%
Frequency Resolution		0.0025% 10000 steps / decade
AC Voltage Amplitude		0 to 2 V, 24 bit resolution 0 to 6 V, 24 bit resolution		5 V range 14 V range
AC Current Amplitude		0 to 2 A, 24 bit resolution		in 12 current ranges

IM7

Table 8 IM7 Specifications

General
Overall Bandwidth	DC - 10 MHz
ADC resolution	32 bit DC		24 bit AC
Harmonic Reject	> 60 dB @ ½ full scale
Potentiostat Modes	potentiostatic, galvanostatic, OCP, ZRA, FRA, off
Cell Connection	2-, 3-, 4-terminal kelvin
Ground Reference	grounded, floating (switchable)
Interface	Gigabit ethernet (GbE)
Memory	40 GB (SSD), SD-card slot (system recovery)
Extension Slots	4
Dimensions (H x W x D) in mm	160 x 364 x 376
Weight	11.4 kg
Accessories	LoZ-cable set, HiZ-cable set, testbox, dummycell, LAN cable, mains cable, Zahner Analysis licence sheet, safety precautions quickstart installation guide (with Zahner Lab link)
Power Supply	100/115/230 VAC, 50/60 Hz, 300 W
Ambient Temperature	+10 °C to +30 °C
Ambient Humidity	< 60 % without derating
Storage Temperature	-20 °C to +85 °C
Input
Maximum Sampling Rate		900 kHz at up to 2 channels		3.0 MSps total sampling rate
Maximum Input Voltage		±5.5 V ±16 V		5 V range 15 V range
Voltage Resolution		±3.2 nV ±9.6 nV		5 V range, gain 100 15 V range, gain 100
Voltage Accuracy		±50 µV ± 5 ppm of reading ±150 µV ± 15 ppm of reading		5 V range 15 V range
DC Current Resolution		±2 aA		32 bit
DC Current Accuracy		±0.5% of reading ± 0.2% of FS ±0.05% of reading ± 0.02% of FS ±0.5% of reading ± 0.2% of FS ±0.5% of reading ± 125 fA		100 mA … 3 A 3 µA … 300 mA 30 nA … 3 µA < 30 nA
Input Impedance		> 10 TΩ, ±5 pF		typical
Input Leakage Current		< 200 fA 2 pA		typical maximum
Impedance Range		10 µΩ to 100 GΩ		see IM7 accuracy contour plot for detailed information about EIS accuracy and conditions.
Common Mode Rejection		> 86 dB > 66 dB		10 µHz to 100 kHz 100 kHz to 8 MHz
Input Channel Phase-tracking Accuracy		±0.05 deg ±0.125 deg		10 µHz to 100 kHz 100 kHz to 8 MHz
Equivalent Effective Input Noise		1 µV rms, 100 fA rms		1 mHz to 10 Hz
Output Potentiostatic
Controlled Voltage		±5 V ±15 V		5 V range 15 V range
Resolution		±2.5 nV ±7.5 nV		5 V range 15 V range
Accuracy		±150 µV ± 15 ppm of reading ±450 µV ± 45 ppm of reading		5 V range 15 V range
Integral Nonlinearity		typ. 2 ppm, max. 4 ppm typ. 6 ppm, max. 12 ppm		5 V range 15 V range
Compliance Voltage		±14 V ±28 V		low compliance mode high compliance mode
Bandwidth		10 MHz		@ 33 Ω load
IR Compensation		auto AC impedance technique range 0 to 10 MΩ resolution 0.012%
Small Signal Rise Time		150 ns to 200 µs in 5 steps		automatic selection
Slew Rate		15 MV/s
Output Galvanostatic
Controlled Current		±3 A
Current Ranges		±3 nA to ±3 A		in 12 steps
Resolution		±0.2 ppm of FS		32 bit
Accuracy		±0.05% of reading ± 0.02% of FS ±0.2% of reading ± 0.1% of FS		> 3 µA … 300 mA < 3 µA or > 300 mA
Frequency Generator and Analyzer
Frequency Range		10 µHz to 8 MHz
Frequency Accuracy		< 0.0025%
Frequency Resolution		0.0025% 10000 steps / decade
AC Voltage Amplitude		0 to 2 V, 24 bit resolution 0 to 6 V, 24 bit resolution		5 V range 15 V range
AC Current Amplitude		0 to 2 A, 24 bit resolution		in 12 current ranges

IM7x

Table 9 IM7x specifications

General
Overall Bandwidth	DC - 15 MHz
ADC resolution	32 bit DC		24 bit AC
Harmonic Reject	> 60 dB @ ½ full scale
Potentiostat Modes	potentiostatic, galvanostatic, OCP, ZRA, FRA, off
Cell Connection	2-, 3-, 4-terminal kelvin
Ground Reference	grounded, floating (switchable)
Interface	Gigabit ethernet (GbE)
Memory	40 GB (SSD), SD-card slot (system recovery)
Extension Slots	9
Dimensions (H x W x D) in mm	160 x 255 x 385
Weight	13.2 kg
Accessories	LoZ-cable set, HiZ-cable set, testbox, dummycell, LAN cable, mains cable, Zahner Analysis licence sheet, safety precautions quickstart installation guide (with Zahner Lab link)
Power Supply	100/115/230 VAC, 50/60 Hz, 400 W
Ambient Temperature	+10 °C to +30 °C
Ambient Humidity	< 60 % without derating
Storage Temperature	-20 °C to +85 °C
Input
Maximum Sampling Rate		900 kHz at up to 2 channels		3.0 MSps total sampling rate
Maximum Input Voltage		±5.5 V ±16 V		5 V range 15 V range
Voltage Resolution		±3.2 nV ±9.6 nV		5 V range, gain 100 15 V range, gain 100
Voltage Accuracy		±50 µV ± 2 ppm of reading ±150 µV ± 5 ppm of reading		5 V range 15 V range
DC Current Resolution		±2 aA		32 bit
DC Current Accuracy		±0.5% of reading ± 0.2% of FS ±0.05% of reading ± 0.02% of FS ±0.5% of reading ± 0.2% of FS ±0.5% of reading ± 125 fA		300 mA … 4 A 3 µA … 300 mA 30 nA … 3 µA < 30 nA
Input Impedance		> 10 TΩ, ±5 pF		typical
Input Leakage Current		< 200 fA 2 pA		typical maximum
Impedance Range		10 µΩ to 100 GΩ		see IM7x accuracy contour plot for detailed information about EIS accuracy and conditions.
Common Mode Rejection		> 86 dB > 66 dB		10 µHz to 100 kHz 100 kHz to 12 MHz
Input Channel Phase-tracking Accuracy		±0.05 deg ±0.125 deg		10 µHz to 100 kHz 100 kHz to 12 MHz
Equivalent Effective Input Noise		1 µV rms, 100 fA rms		1 mHz to 10 Hz
Output Potentiostatic
Controlled Voltage		±5 V ±15 V		5 V range 15 V range
Resolution		±2.5 nV ±7.5 nV		5 V range 15 V range
Accuracy		±150 µV ± 5 ppm of reading ±450 µV ± 25 ppm of reading		5 V range 15 V range
Integral Nonlinearity		typ. 1 ppm, max. 2 ppm typ. 3 ppm, max. 8 ppm		5 V range 15 V range
Compliance Voltage		±16 V ±32 V		low compliance mode high compliance mode
Bandwidth		12 MHz		@ 33 Ω load
IR Compensation		auto AC impedance technique range 0 to 10 MΩ resolution 0.012%
Small Signal Rise Time		150 ns to 200 µs in 5 steps		automatic selection
Slew Rate		15 MV/s
Output Galvanostatic
Controlled Current		±4 A
Current Ranges		±3 nA to ±4 A		in 12 steps
Resolution		±0.2 ppm of FS		32 bit
Accuracy		±0.05% of reading ± 0.02% of FS ±0.1% of reading ± 0.05% of FS		> 3 µA … 300 mA < 3 µA or > 300 mA
Frequency Generator and Analyzer
Frequency Range		10 µHz to 12 MHz
Frequency Accuracy		< 0.0025%
Frequency Resolution		0.0025% 10000 steps / decade
AC Voltage Amplitude		0 to 2 V, 24 bit resolution 0 to 6 V, 24 bit resolution		5 V range 15 V range
AC Current Amplitude		0 to 2 A, 24 bit resolution		in 12 current ranges

Cell Connection Scheme

All Zahner potentiostats and power potentiostats follow the same cell connection scheme (4-electrodes connection scheme). The 4-electrode connection scheme includes connections for working electrode (WE), working electrode sense (WEs), reference electrode (RE), and counter electrode (CE). These connections are specified by their color code, WE: black, WES: blue, RE: green, and CE: red. To minimize interference, stray- and mutual inductance, the red and black power cables (current carrying cables) must be twisted together, and the green and blue sense cables must be twisted together before the measurement. Twisting is not shown in the schematic below.

Fig. 1 4-electrode connection scheme. The current is carried through the black (WE) and red (CE) wires. The voltage is measured between the green (RE) and blue (WEs) wires.

For large current flow the object must be connected with a four-electrode connection scheme in order to minimize the error margin in the measurement.

Contact Resistance

This figure shows a typical electrical wire used to connect the potentiostat with the test object. The resistance of the wire can be divided in to two parts (wire resistance and contact resistance).

Fig. 2 Typical electrical wire used to contact potentiostat with the test object. Resistance of the electrical wire is divided in to two different parts. 1) contact resistance and 2) wire resistance.

Two Electrode Cell Connection Scheme

Here a 2-electrode cell connection scheme is used for measurements on a cell. The WE and WEs cables are joined together to make one electrode connection and RE and CE cables are joined together to make the second electrode connection.

Fig. 3 The measured impedance (between RE and WEs electrodes) is the sum of the cell impedance and both contact impedances.

This means that the measured voltage is the sum of the object voltage and the two voltage drops across the contact resistances.

Four Electrode Cell Connection Scheme

The advantage of a 4-electrode connection scheme is illustrated here. With the WEs and RE being directly connected to the cell, the contact resistance for the WE and CE can be ignored as they don’t affect the voltage value (not possible with 2-electrode connection scheme).

Fig. 4 Four-electrode connection scheme and equivalent circuit diagram for a 2-electrode pouch cell.

For optimum measurement results, the WE and CE as well as the RE and WEs cables must be twisted together (not shown in the image).

Due to the high input impedance of the potentiostat the input current to the sense inputs is negligible. This means that there are no voltage drops across the contact resistances of the Sense connections. With the 4-electrode connection scheme, the contact resistances are in most cases not significant in the measured cell impedance. This is only true if the cell resistance of the test object is much smaller than the input resistance of the potentiostat. The input impedance of the potentiostat is provided in the specifications.

Electrode Setups

Two Electrode Setup

The simplest cell setup has only two connections. A working electrode is connected to the WE and WEs terminals, while the counter electrode (or auxiliary or pseudo-reference electrode) is connected to CE and RE. This means that current-carrying leads are connected to voltage-measuring leads in pairs.

In two-electrode experiments, voltage errors are measured at both connections, which complicates analysis of the results.

Two-electrode arrangements are used when measurement of the total cell voltage is required (e.g., batteries, fuel cells, supercapacitors). However, it is still very important that the cell be connected in a Kelvin arrangement as effectively as possible to eliminate series impedances.

Note

Four separate leads are used in the Kelvin measurement method. Two leads carry current through the test object. The other two leads measure the voltage drop. A constant current flows through the test object that is independent of the supply line resistance.

Three Electrode Setup

The three-electrode setup is the most common configuration in electrochemistry. In contrast to the two-electrode setup, the RE connection is separate from the CE connector. Instead, a third electrode (reference electrode) is used to measure the potential in the immediate vicinity of the working electrode. This isolation enables analysis of specific reactions with greater certainty and accuracy.

Four Electrode Setup

The four-electrode configuration is less commonly used. In addition to the reference electrode (RE), the sense connection of the working electrode (WEs) is also separated from the working electrode (WE).

When measuring with the four-electrode setup, a potential difference is measured in the region between the potentials of the working and counter electrodes. This can be the solution itself or a barrier (e.g., membranes) within this solution.

This setup enables very precise measurements of solution resistance or resistance at the surface of a material.

Calibration

Calibrating our measurement instruments at the end of the production process is an essential step to ensure the accuracy and reliability of measurement data. During this process, instruments are compared against standardized reference values and adjusted as necessary to ensure they meet specified tolerances.

Factory Calibration

Calibration data is stored in the individual devices, so it is not necessary to install any calibration files. Each device is supplied with a USB stick containing instructions to install the Zahner Lab software.

Warm-up Time

A key aspect of calibration is the warm-up period of the measurement device, as many devices only reach optimal performance after a certain period of operation. This phase allows the device to stabilize and adjust temperature-sensitive components, which significantly improves calibration validity.

Note

This state is typically reached after approximately 30 minutes of operation.

Recalibration

To maintain measurement accuracy, it is recommended that calibration be renewed at regular intervals. This interval depends on various factors, including device type, application, and environmental conditions.

Generally, a timeframe of two to three years is considered practical, although more frequent calibration may be appropriate for particularly critical applications. Consistent implementation of these measures ensures the long-term reliability and accuracy of measurement systems.

Hardware Service Instructions

Note

The main card set and the expansion cards cannot be exchanged between different ECWs, as the cards must be calibrated with each other. If cards are exchanged without calibration data, measurements will fail.

The following general instructions apply to all work on the measurement device hardware:

1. Before opening the housing, the device must be switched off and the power cord disconnected!

2. The measurement cards are particularly sensitive to electrostatic discharge. Use of an ESD protection mat and ESD discharge wrist strap is therefore recommended for all work!

3. Removed measurement cards must be stored and transported in suitable electrostatically shielded foil bags!

Removal and Installation of the Potentiostat Card Set

In the event of a device fault, it may be necessary to remove the measurement card set of the potentiostat. However, this should only be done if the manufacturer expressly recommends it for repairs.

1. Unscrew all four screws on the rightmost front panel until they are loose. The screws remain in the front panel.

2. Carefully remove the front panel. If it sticks to the potentiostat sockets, carefully wiggle it loose.

3. Carefully pull out the two front bus boards with pliers without tilting them.

4. Pull out the leftmost card first. This is the function generator (FUGE).

5. Now pull out the next card. This is the parallel ADC card (PAD).

6. Now pull out the next card. This is the current measurement card and the DC measurement card (SHUNT).

7. Take hold of the POT card, which is connected to the POT front panel, by the BNCs and carefully pull it out slightly.

8. Disconnect the ribbon cable and pull out the POT card together with the POT front panel. There is a safety clip on the ribbon cable (at the bottom) which must be pressed down.

9. The removed circuit boards must be stored and dispatched in a suitable shielding bag.

10. To reassemble, reinsert all the cards in reverse order and press them firmly into place. The plug-in strips on the bus must engage correctly.

11. Once you have inserted all the cards, replace the two front bus boards and press them firmly into place. The arrow on the boards must point upwards!

Installation of Extension Cards

The IM7 supports up to four expansion cards, while the IM7x can accommodate up to nine expansion cards.

The IM7c does not have expansion slots and can only be expanded using probes at the potentiostat front end (E/I Probe connector).

1. Loosen all screws on the blank front panel (Extension) until they are loose, but leave the screws in the front panel. Carefully remove the front panel.

2. Insert the add-on card along the red guide rails into the available extension slot.

3. Insert the expansion card along the red guides into the available expansion slot.

4. Press the card firmly into the slot and tighten the two front panel screws.

Note

After installation, all expansion bays should be covered with blank front panels. These blank front panels are available as accessories.

Diagnostics and Troubleshooting

Zahner instruments feature internal self-test diagnostic procedures that detect hardware problems due to internal device failure or degradation in virtually all cases. Nevertheless, electrochemical experiments can present unexpected challenges even to experienced users and measurement results that contradict the scientist’s expectations may occur. In most cases, these issues can be resolved by carefully checking the wiring and test setup, while considering their parasitic properties. To ensure that no instrument problems are present, a detailed testing feature called TestBox and Dummycell is provided.

Testbox

The test box can be used to check the functionality of the measuring device independently of measuring cables in the high-impedance and low-impedance range. The two equivalent circuit diagrams can be selected using the slide switch.

Testbox HiZ

A potentiostatic EIS is used on the high-impedance R-C element to check the AC calibration. Different current ranges are used due to the impedance dynamics. In the high-frequency part of the spectrum (f > 1 kHz), the capacitive phase should remain constant at -90°.

Recommended parameterisation:

• PEIS

• amplitude 10 mV

• DC bias 0 V

• start frequency 1 kHz

• maximum frequency 1 MHz

• minimum frequency 100 mHz

PEIS spectrum of the Testbox HiZ object

Testbox LoZ

To test the current ranges, a replacement circuit diagram consisting of two anti-parallel diodes can be measured in the LoZ position. The diodes have an exponential U/I characteristic curve, allowing the current to be tested across all current ranges.

Recommended parameterisation:

• CV

• scanrate 5 mV/s

• start bias 0 V

• first vertex 1 V

• second vertex -1 V

• end bias 0 V

• ODR 10 1/s

• number of cycles 0.5

• autorange enabled

• turn limit checks enabled

• upper turn value 1 A

• lower turn value -1 A

CV of the Testbox LoZ object

Dummycell

In addition to the test box, other replacement circuits can be tested using the dummy cell. The dummy cell is connected to the potentiostat using the cable sets supplied. In principle, both cable sets can be used. This also allows the measuring cables to be tested for functionality.

10 mΩ Resistor

With a resistance of 10 mΩ, galvanostatic tests can be performed up to a maximum of 5 A (depending on the device). For impedance spectroscopy, the two measurement signals (RE/WEs) are connected separately from the two current connections (CE/WE). This minimises interference from the current-carrying circuit in the measurement connections.

Recommended parameterisation:

• GEIS

• amplitude 100-1000 mA

• DC bias 0 A

• start frequency 1 kHz

• maximum frequency 1 MHz

• minimum frequency 100 mHz

GEIS spectrum of the 10 mΩ resistor

100Ω Resistor

The 100 Ω resistor can be used for potentiostatic tests up to a maximum voltage of 10 V. This is determined by the maximum power dissipation of the resistor. With this object impedance, the measuring terminals no longer need to be divided into current-carrying and voltage-measuring terminals.

Recommended parameterisation:

• PEIS

• amplitude 10 mV

• DC bias 0 V

• start frequency 1 kHz

• maximum frequency 1 MHz

• minimum frequency 100 mHz

PEIS spectrum of the 100 Ω resistor

Extended Randles Circuit

The extended Randles circuit enables impedance spectra to be measured with two different time constants. The additional reference connections in the middle (RE1, RE2) can be used, for example, with a PAD42 card to analyse the individual half-cells.

Recommended parameterisation:

• PEIS

• amplitude 10 mV

• DC bias 0 V

• start frequency 1 kHz

• maximum frequency 1 MHz

• minimum frequency 100 mHz

PEIS spectrum of the extended randles circuit

Custom Experiment

For quick analysis of the measuring device, a series of standardised measurements can be run automatically using the test box and dummy cell. The Zahner Lab software includes the custom experiment “Test box and dummy cell” for this purpose.