PP2x2

The PP2x2 are 4-quadrant power potentiostats designed to apply and sink high currents up to up to ±40 A at a voltage range up to ±20 V (max. power 200 W) depending on the model.

For medium power applications, the PP2x2 is used as an extension of the IM7 series potentiostat. Most electrochemical techniques which can be performed with the main IM7 potentiostat can also be carried out with the extended power potentiostat PP242 setup.

Besides an extension, the PP2x2 power potentiostat can also be used in stand-alone mode for standard DC measurements i.e., charging/discharging of batteries. Zahner’s new Zahner Lab software controls the potentiostat during stand-alone operations.

The Zahner’s power potentiostats can be incorporated in a Python lab environment and can be used as stand-alone or in multi-channel configurations. A GitHub repository with examples is available for developing Python applications.

• Power extension of IM7 potentiostat for battery, fuel cells, or electrolyzer stack measurements

• Possible integration in a Python work environment

• Standalone operation for simple DC measurements

Packing List

• Power potentiostat (PP212 or PP222 or PP242)

• EPC42 cable

• USB cable

• Cell cable set:

  • Twisted sense cable (Lemosa plug to blue & green cables)

  • PP212/PP222:

    • 2 cables (red and black) with banana plugs ( 4mm), (Length: 1m)

    • Rated for a maximum current of up to 32 A

    • 2 alligator clips (red and black)

  • PP242:

    • 2 cables (red and black) with cable lugs, (Length: 1m)

    • Recommended use for a maximum rated current of up to 40 A

• Power cord

• Ring binder

  • Calibration report PP2x2

  • Risk assessment document

  • Zahner Analysis license keys

  • Product manual description

Caution

Caution

Prevent the inputs of the potentiostat from electrostatic discharge (ESD)! ESD may damage the potentiostat. ESD related damages are not covered in warranty of the potentiostat. The user must discharge his-/herself from any electrical charge before touching the potentiostat (TIP!: use grounded ESD-matts).

Please read the risk assessment document before operating the potentiostat.

Zahner’s potentiostats require a warm-up time of 30 minutes for optimum performance.

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

To drive more than 32 A with the PP242 the customer must use a cable, recommended for high current applications and fix it to the front terminal CE and WE with suitable cable lugs.

Properly connect (with screws) the EPC42 cable with the electronic load. An accidental unplugging of the EPC42 cable during operation may damage your device.

Don’t touch the electrical connections during the operation.

The cables must be as short as possible and as thick as possible.

Introduction

Zahner’s power potentiostats PP212, PP222, PP242 can be used as an extension to the IM7 series potentiostats or in a stand-alone configuration. In the following sections, both scenarios are discussed.

Modular concept - extension to IM7 series potentiostat

Dynamic measurements (e.g. impedance spectroscopy) on electrochemical objects is a topic of interest in the field of electrochemistry. Modern instruments can cover a broad frequency range from µHz to MHz and operate with huge impedance range from µΩ to GΩ. However, the maximum applied current is mostly limited to a few amperes. For many applications in the field of battery and fuel cell, high currents are needed. For IM7 series potentiostats, the current range can be extended via Zahner’s power potentiostats (PP212/PP222/PP242).

With IM7 series potentiostat and power potentiostats, precise measurements can be carried out at high applied currents. The four-quadrant power potentiostats (PP212/PP222/PP242) provide up to ±40 A (PP242) or up to ±20 V (PP212) with a maximum power output of 200 W. To connect a power potentiostat with the IM7 potentiostat, an EPC42 interface card is used.

Caution

External power potentiostats connected to the IM7 series can only be operated sequentially. Simultaneous control of multiple power potentiostats is not supported.

Never connect or disconnect the D-SUB connector on the rear of the power potentiostat while either of the two devices is switched on. Failure to observe this precaution may result in damage to both the device and the test object.

Secure the D-SUB connector with the provided screws to prevent accidental disconnection.

When switching between devices, the non-selected external potentiostat will maintain its DC conditions, including DC potential or current and on/off status.

Voltage and current outputs of non-selected external potentiostats are neither measured nor monitored for compliance with defined voltage/current limits.

Only the currently selected external potentiostat is internally connected to the FRA (Frequency Response Analyzer) of the IM7 series potentiostat. Consequently, only the active external potentiostat can generate AC signals.

Stand-alone mode

Zahner’s power potentiostats or electronic loads (PP2X2, XPOT2, EL1002) can also be operated in stand-alone mode, for which a Windows 10/11 or Linux computer is necessary. For software updates, Windows 10/11 is required and the use of a virtual machine is not permitted. The application of a USB hub for connecting the device is not recommended.

The PP2X2/XPOT2/EL1002 potentiostat can also be controlled with other third-party software (e.g., Python). This allows for the integration in already established experimental setups. The potentiostats provide serial interfaces via the USB serial port which can be used to communicate with the potentiostat via the SCPI protocol. In the future, it is planned that the ethernet interface will be activated via a free software update.

Zahner has prepared a GitHub library for controlling the PP2X2/XPOT2/EL1002 potentiostats with Python via SCPI:

https://github.com/Zahner-elektrik/zahner_potentiostat

And a GitHub repository with examples using the library:

https://github.com/Zahner-elektrik/Zahner-Remote-Python

The API documentation can be found at:

https://doc.zahner.de/zahner_potentiostat

Only DC measurements can be carried out in the stand-alone mode.

Measuring Floating Objects

On the rear of the power potentiostats (PP2X2 and XPOT2), two connectors with a jumper are provided. If the jumper is set, the signal ground is connected to ground via a 100 Ω protective resistor. When examining grounded objects, the jumper on the back of the instrument must be removed. Otherwise, the device and the test object may get damaged.

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. 5 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. 6 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. 7 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. 8 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

The PP2X2 are external four-quadrant potentiostats and are able to sink and source current up to ±10/±20/±40 A, depending upon the power potentiostat model.

The PP2x2 as power potentiostats to the IM7 series potentiostats can be used to carry out DC measurements (charging/discharging measurements) as well as AC measurements (electrochemical impedance spectroscopy). The power potentiostats can be operated in both potentiostatic and galvanostatic modes. The output as well as the input is electrically isolated up to a maximum potential difference of ±12 V (for PP222 and PP242) and of ±24 V (for PP212) against ground potential.

In the following sections, different experimental scenarios are described in which the PP2X2 power potentiostats (with IM7 series potentiostats) can be used to characterize the cell (fuel cell, electrolysers or battery) in

1. Full cell configuration

2. Half-cell configuration (anodic or cathodic part)

3. Partial cell configuration.

Full Cell Configuration

This configuration is used if a complete cell is to be investigated. It is also known as Standard Kelvin Scheme.

Fig. 9 Cable connection schematic for full cell characterization. WE and WEs connections are connected to the one electrode of the cell and RE and CE connections are connected to the other electrode. Current carrying cables (WE and CE cables) and sense cables (WEs and RE cables) are twisted together to minimize the artefacts. The main IM7 series potentiostat is not shown in the schematic.

Half Cell Configuration (Anode)

This configuration is used if the anodic part of the cell is to be investigated. Here the voltage is measured between anode and a reference electrode.

Fig. 10 Cable connection schematic for characterizing the anode of the cell. Current is applied/measured between the anode and cathode whereas voltage is measured between the anode and a reference electrode (Ref). Current carrying cables (WE and CE cables) and sense cables (WEs and RE cables) are twisted together to minimize the artefacts. The main IM7 series potentiostat is not shown in the schematic

Half Cell Configuration (Cathode)

This configuration is used if the cathodic part of the cell is to be investigated. Here the voltage is measured between cathode and a reference electrode.

Fig. 11 Cable connection schematic for characterizing the cathodic part of the cell. Current is applied/measured between the anode and cathode whereas voltage is measured between the cathode and a reference electrode (Ref). Current carrying cables (WE and CE cables) and sense cables (WEs and RE cables) are twisted together to minimize the artefacts. The main IM7 series potentiostat is not shown in the schematic.

Partial Cell configuration

This configuration may be used, if a certain part of a battery or fuel cell stack has to be investigated.

Fig. 12 Cable connection schematic for characterizing a part of the cell. Current is applied/measured between the anode and cathode whereas voltage is measured between two reference electrodes (Ref1 and Ref2). Current carrying cables (WE and CE cables) and sense cables (WEs and RE cables) are twisted together to minimize the artefacts. The main IM7 series potentiostat is not shown in the schematic.

Battery Configuration

In this configuration, the battery is connected in such a way that a positive open circuit potential can be read.

Fig. 13 Cable connection schematic for full cell characterization. WE and WEs connections are connected to the one electrode of the cell and RE and CE connections are connected to the other electrode. Current carrying cables (WE and CE cables) and sense cables (WEs and RE cables) are twisted together to minimize the artefacts. The main IM7 series potentiostat is not shown in the schematic.

Specifications

In the following subsections, current and voltage ranges for different power potentiostats are provided for use with IM7 series measurement (Range IM7) and for stand-alone mode.

Ranges and tolerances

PP212

Table 10 PP212 Voltage Ranges

Voltage Ranges
Voltage Range		Range Standalone [V]		Range IM7 [V]		Tolerance
Index	Factor	min	max	min	max
0	1	-10	10	-8	8	±1000 µV ±0.1% of reading
1	0,4	-20	20	-20	20	±2500 µV ±0.1% of reading

Table 11 PP212 Current Ranges

Current Ranges
Shunt		Range Standalone [A]		Range IM7 [A]		Tolerance
Index	Resistance	min	max	min	max
0	10m	-10	10	-10	10	±400 mA ±0.2% of reading
1	100m	-10	10	-10	10	±40 mA ±0.2% of reading
2	1	-2	2	-2	2	±4 mA ±0.2% of reading
3	10	-400m	400m	-400m	400m	±400 µA ±0.2% of reading

PP222

Table 12 PP222 Voltage Ranges

Voltage Ranges
Voltage Range		Range Standalone [V]		Range IM7 [V]		Tolerance
Index	Factor	min	max	min	max
0	1	-5	5	-4	4	±500 µV ±0.1% of reading
1	0,4	-10	10	-10	10	±1250 µV ±0.1% of reading

Table 13 PP222 Current Ranges

Current Ranges
Shunt		Range Standalone [A]		Range IM7 [A]		Tolerance
Index	Resistance	min	max	min	max
0	10m	-20	20	-20	20	±400 mA ±0.2% of reading
1	100m	-20	20	-20	20	±40 mA ±0.2% of reading
2	1	-2	2	-2	2	±4 mA ±0.2% of reading
3	10	-400m	400m	-400m	400m	±400 µA ±0.2% of reading

PP242

Table 14 PP242 Voltage Ranges

Voltage Ranges
Voltage Range		Range Standalone [V]		Range IM7 [V]		Tolerance
Index	Factor	min	max	min	max
0	1	-5	5	-4	4	±500 µV ±0.1% of reading
1	0,4	-10	10	-10	10	±1250 µV ±0.1% of reading

Table 15 PP242 Current Ranges

Current Ranges
Shunt		Range Standalone [A]		Range IM7 [A]		Tolerance
Index	Resistance	min	max	min	max
0	10m	-40	40	-40	40	±400 mA ±0.2% of reading
1	100m	-40	40	-40	40	±40 mA ±0.2% of reading
2	1	-2	2	-2	2	±4 mA ±0.2% of reading
3	10	-400m	400m	-400m	400m	±400 µA ±0.2% of reading

General specifications

Table 16 PP2x2 General specifications

	PP212	PP222	PP242
Potentiostatic Modes	Potentiostatic, Galvanostatic, Pseudo-Galvanostatic, Off
Cell Connection	2-, 3-, 4-Terminal Sensing
Ground Reference	Grounded, Floating
Compliance Voltage	±20 V	±10 V	±5 V
Maximum Current	±10 A	±20 A	±40 A
Output Power	200 W
Power Dissipation	250 W
Input Impedance	2 MΩ	100 MΩ
Equivalent Input Noise	< 10 µV rms
Memory	64 GB
Interface	USB, Ethernet 2
Additional IOs	5 2
Additional Analog Outputs	1 2
Additional Analog Inputs	4 2
Temperatur Sensor Interface	Type K 2
Ambient Temperature	10 °C - 30 °C
Maximum Humidity	60 %
Dimensions (H x W x D) in mm	160 x 364 x 378
Weight	10.2 kg
SCPI (Stand-alone Mode) 3
ADC Resolution	24 bits
Voltage Input Resolution	1.192 µV	0.596 µV
Current Input Resolution	5.96 nA
DAC Resolution	18 bits
Voltage Output Resolution	76.3 µV	38.14 µV
Current Output Resolution	3.81 µA
IM7 (EPC Mode) 3
ADC Resolution	24 bits
Voltage Input Resolution	1.192 µV	0.596 µV
Current Input Resolution	5.96 nA
DAC Resolution	16 bits
Voltage Output Resolution	250 µV	125 µV
Current Output Resolution	12.5 µA
Impedance Frequency Range	10 µHz - 400 kHz
Impedance Range	1 µΩ - 1 kΩ1

¹ Impedances below 10 mΩ must be measured galvanostatically.

² Hardware feature will be unlocked in the future by a free software update.

³ The specifications for the resolution are given for the smallest current and voltage range.

Safe operating conditions

In this section, the safe operating ranges for the power potentiostats are provided. In the tables, the “power loss” is taken as an indicator of safe operating conditions. The PP2X2 potentiostats can accommodate a maximum power loss of up to 250 W. A higher power loss will trigger the safety precautions setup of the potentiostats and the output will be limited.

Caution

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

PP212

Fig. 14 PP212 SOA

PP222

Fig. 15 PP222 SOA

PP242

Fig. 16 PP242 SOA