How to Choose Electrodes? A Practical Guide to the Three-Electrode System
In the field of battery and electrochemical research, precise electrochemical testing is not just the key to uncovering reaction mechanisms—it’s essential for optimizing battery performance and developing next-generation energy materials. The combination of a three-electrode system and an electrochemical workstation has become standard equipment in virtually every research laboratory.
So, what exactly is a three-electrode system? What roles do the three electrodes play? And how should you select the right electrode materials for your experiments? Today, Beyond Battery takes you from fundamental principles to practical tips in the world of electrodes.
What is a Three-Electrode System?
In electrochemical experiments, researchers often need to study reactions at specific electrodes while precisely controlling and measuring potentials under different conditions. This is where the three-electrode system comes in.
A typical three-electrode electrochemical cell consists of:
- Working Electrode (WE)
- Reference Electrode (RE)
- Counter Electrode (CE)
An electrochemical workstation controls and measures the potential between the working electrode and the reference electrode, while simultaneously recording the current passing through the working electrode. This setup enables detailed investigations into reaction kinetics, mechanisms, and battery performance.
For high-sensitivity measurements, studies of charge-transfer processes, or in-depth analysis of electrode reaction mechanisms, the three-electrode system is virtually indispensable.
Working Electrode (WE)
The working electrode is the core of the electrochemical cell—it’s where the reaction of interest occurs. In photoelectrochemical studies, the working electrode often doubles as a photoelectrode.
An ideal working electrode should:
- Remain inert and not participate in side reactions with the electrolyte or target species
- Maintain chemical stability across a broad potential window
- Have a smooth, uniform surface that’s easy to clean and reuse
- Be appropriately sized—not too large to cause excessive currents or poor signal resolution
Common Working Electrode Materials
Different research applications require different working electrode materials, such as:
• Inert solid electrodes: glassy carbon, platinum (Pt), gold (Au), silver (Ag), lead (Pb), or conductive glass like FTO and ITO
• Liquid electrodes: mercury (Hg) and amalgams
Liquid electrodes like mercury offer a reproducible homogeneous surface and a high hydrogen overpotential, making them popular in high-sensitivity electrochemical analyses.
Why Pre-Treatment of Electrodes Matters
Solid electrodes can accumulate surface impurities or undergo redox reactions that affect measurements. For this reason, pre-treatment steps—such as polishing, cleaning, or electrochemical activation—are typically performed before experiments to ensure reproducibility and reliable results.
Reference Electrode (RE)
The reference electrode is the “voltage ruler” in an electrochemical system. It carries virtually no current yet provides a stable potential against which the working electrode’s potential is measured.
An ideal reference electrode should:
• Have a well-known, stable potential with excellent reproducibility
• Possess high exchange current density, making it non-polarizable or minimally polarizable
• Not react with the electrolyte or interfere with the experimental system
• Exhibit a low temperature coefficient, ensuring minimal potential shifts with temperature changes
• Avoid leaking ions that could influence the working electrode’s reactions
Common Reference Electrodes:
• Silver/Silver Chloride Electrode (Ag/AgCl Electrode)
• Saturated Calomel Electrode
• Mercury/Mercuric Oxide Electrode (Hg/HgO Electrode)
• Mercury/Mercurous Sulfate Electrode (Hg/Hg₂SO₄ Electrode)
• Reversible Hydrogen Electrode (RHE)
Counter Electrode (CE)
Also known as the auxiliary electrode, the counter electrode completes the current circuit with the working electrode, ensuring that the desired reactions occur reliably on the working electrode’s surface.
Unlike the working electrode, the counter electrode is usually larger and simpler in shape. Its primary functions are:
• Providing excellent electronic conductivity
• Distributing the applied potential evenly to avoid influencing the working electrode’s potential
• Remaining chemically inert, without participating in unwanted side reactions
Common Counter Electrode Materials
• Platinum wire or plates (Pt): highly conductive and inert but relatively expensive; prolonged testing may cause platinum dissolution and redeposition onto the working electrode, potentially affecting results.
• Graphite rods or plates: chemically stable, cost-effective, and suitable for long-duration experiments or higher current densities.
Why Is the Counter Electrode’s Surface Area Important?
For a given current, a larger electrode surface reduces current density, minimizing overpotential. This enhances the sensitivity of the electrochemical system and reduces experimental noise. When the working electrode surface is very small, polarization effects on the counter electrode become negligible, and its potential remains stable—sometimes allowing it to serve as a quasi-reference electrode. Similarly, different types of electrode clips are frequently used in experiments to secure the counter electrode in the electrolyte and maintain good electrical contact.
How to Choose the Right Electrode?
Selecting electrodes depends on several factors:
• Research objectives (e.g., kinetics, mechanism studies, material characterization)
• Type of electrolyte (acidic, neutral, or alkaline)
• Desired potential window
• Sensitivity requirements for the measurements
• Availability and feasibility of electrode pre-treatment
Researchers often find that choosing electrodes isn’t just about buying hardware—it’s about tailoring the entire electrochemical setup to their specific system.
At Beyond Battery, we offer a broad range of electrode materials and can advise on suitable electrochemical cells, electrode maintenance, and compatible electrolytes for your research needs. If you have any questions about electrode selection or product availability, feel free to contact us!