Потенциостаты & гальваностаты

Почему потенциостаты Metrohm? – Мы лидеры мирового рынка

Потенциостаты и гальваностаты - Часто задаваемые вопросы

What is a potentiostat? And what is the difference between a potentiostat and a galvanostat?

A potentiostat is an electrochemical instrument that controls the potential difference (voltage) between the working electrode and the reference electrode while measuring the resulting current flow between the working electrode and the counter electrode (also referred to as auxiliary electrode). The potentiostat maintains a constant potential, allowing for precise control and measurement of electrochemical reactions in corrosion studies, electroplating, battery testing, and sensor development.

A galvanostat, on the other hand, is an electrochemical instrument that controls the cell current rather than the cell voltage.

All Metrohm electrochemical instruments combine both potentiostat and galvanostat into a single device. Users can select the appropriate mode (potentiostatic or galvanostatic) based on the experimental requirements.

Learn more about how a potentiostat works and the role of the electrodes used in electrochemical measurements:

Application note: Basic overview of the working principle of a potentiostat/galvanostat (PGSTAT) – electrochemical cell setup

Blog: Fast and fundamental – Influences on reliable electrochemical measurements

Galvanostatic vs. potentiostatic mode

When to choose potentiostatic mode:

• When studying redox reactions, corrosion, electroplating, or any process where maintaining a constant potential is crucial.
• When performing cyclic voltammetry or other techniques that involve sweeping the potential across a range of values.
• When investigating electrochemical behavior, kinetics, and electrode surface properties.

Application note: Potentiostatic intermittent titration technique (PITT)

Application note: ASTM G5 – Potentiodynamic Anodic Polarization Measurements

Application note: Cyclic Potentiodynamic Polarization Measurements as per ASTM G61

When to choose galvanostatic mode:

• When studying electrolysis, electrodeposition, or any process where maintaining a constant current is critical.
• When performing experiments involving fuel cells, batteries, or any electrochemical cell that requires a specific current input.
• When using electrochemical impedance spectroscopy or other techniques that analyze the electrical response of a system.

Application note: Galvanostatic charge-discharge of a Li-ion battery with Autolab

Application note: ASTM G100 – Cyclic Galvanostaircase Polarization

Application note: Galvanostatic Intermittent Titration Technique (GITT)

When to use grounded mode and floating mode in a potentiostat? What is selectable floating?

In a potentiostat, the grounded mode is used when none of the electrodes nor the cell vessel have a direct connection with the ground. This is the most commonly used mode for the vast majority of electrochemical experiments performed in laboratories (i.e., wet electrochemistry research, battery research, corrosion test in lab, etc). If other devices are used during the electrochemical experiments, you can use the faraday cage to ground them.

The floating mode must be used in the following three main cases:

1. When the working electrode is directly connected to the Earth ground (grounded WE): Corrosion tests in open air, hydrogen permeation, in-situ electronic microscopy
2. When the counter electrode is directly connected to the Earth ground (grounded CE): Bioreactors, autoclave
3. When the entire cell is directly connected to the Earth ground (grounded Cell): Tribocorrosion, autoclave

For any of the above-mentioned cases, the correct measurement of the current is only possible if the potentiostat is used with the correct floating mode.

Due to the wide variation of experimental requirements and kinds of electrochemical cells, the use of an electrochemical instrument with a floating feature (such as VIONIC or µStat-i multiX among others) brings additional versatility to the user.

How to choose a suitable potentiostat?

Criteria 1: Voltage and current range

Consider the range of potentials and currents you expect to work with.

• Basic requirement: Compliance voltage up to ± 10 V, max. current up to ± 100 mA: PGSTAT101, Autolab IMP, μStat-i 400 – Small, lightweight, and affordable
• Moderate requirement: Compliance voltage ± 20 V, max. current ± 400 mA: PGSTAT204 – Small and able to add one more module (e.g. EIS)
• Advanced requirement: Compliance voltage ± 30 V, max. current ±2 A (upgradeable) : PGSTAT302N – Customizable with a range of modules
• Stringent requirement: Compliance voltage ± 50 V, max. current ± 6 A: VIONIC powered by INTELLO – Highest specification and multi-modules in one instrument

Criteria 2: Is high-throughput or multichannel a need?

If you plan to run multiple experiments simultaneously, you might need a potentiostat with multiple channels.

Go to Mulitchannel Line

Go to Portable Multichannel Line

Criteria 3: Portability

A portable potentiostat can be beneficial in various scenarios where mobility, fieldwork, or on-site measurements are necessary. Metrohm can provide both single-channel and multi-channel portable potentiostats.

Go to Portable Singlechannel Line

Go to Portable Multichannel Line

Criteria 4: Hyphenated Electrochemistry with third party instruments or Spectroelectrochemistry integrated into one instrument