As a common metal material in electrochemistry, copper's role as an electrode is often discussed - is
it an anode or a cathode? In this paper, we will analyze the electrode properties of copper in different
application scenarios from the basic principles, and reveal the unique properties of this metal material.
Basic Concepts of Electrodes
In the electrochemical system, the determination of electrode properties need to understand the two
core concepts: the anode is the electrode for oxidation reaction, the metal atoms lose electrons to be
corroded and dissolved; the cathode is the electrode for reduction reaction, where ions in the solution
gain electrons to be deposited. This division of roles is not fixed, but depends on the potential difference
and metal activity order of the whole system.
Typical scenarios where copper is used as an anode
1. Electrolytic refining process
In the electrolytic refining process of copper, crude copper plates are designed as anodes. When current is passed,
the anode copper undergoes an oxidation reaction (Cu → Cu²⁺ + 2e-), the metallic copper is gradually dissolved
into the electrolyte, and impurities settle to the bottom of the electrolyzer. This application takes full advantage
of the controlled dissolution properties of copper as an anode.
2. Electroplating Applications
When plating other metal substrates, copper is often used as the anode material. For example, in circuit board
manufacturing, the copper anode continuously releases copper ions, which migrate to the surface of the cathode
substrate under the action of an electric field to form a uniform and dense copper plating layer. This dynamic
equilibrium process ensures the quality stability of the coating.
Special applications of copper as cathode
1. Metal replacement reaction
Copper automatically becomes the cathode when it is coupled with more active metals (e.g. zinc, iron). In this
protocell system, the active metal corrodes preferentially as the anode, while the copper cathode is protected.
This phenomenon is practically applied in the sacrificial anode protection method for ship anti-corrosion.
2. Lithium-ion battery technology
In new battery designs, copper foil has been selected as the anode collector because of its excellent electrical
conductivity. Although not directly involved in the electrochemical reaction, but as the hub of electron transfer,
its surface flatness and conductivity efficiency directly affect the overall performance of the battery.
Key factors determining the properties of copper electrodes
1. Comparison of metal activity
Copper and different metal pairs show different characteristics: with silver, gold and other inert metals
combined to become anode; with aluminum, zinc and other active metals with the cathode. This relativity
can be predicted by a standard electrode potential table.
2. External electric field direction
In the forced electrolysis system, the positive and negative connection of the external power supply directly
determines the electrode role. When copper is connected to the positive terminal of the power supply it is
forced to become an anode, and when connected to the negative terminal it turns into a cathode. This
controllability is especially important in industrial plating.
3. Differences in electrolyte environment
Acidic environment in the copper is more likely to be dissolved as anode, and in the solution containing a
strong oxidizer may turn into a cathode. For example, the copper surface in concentrated nitric acid will
form a passivation film, changing its electrochemical behavior.
Technical points in industrial application
1. Optimization of electroplating process
Control the current density in the range of 3-6 A/dm².
Maintain the electrolyte temperature at 45-55℃.
Regular filtration of the solution to remove impurity particles
2. Anti-corrosion system design
Reasonable selection of sacrificial anode materials (zinc, magnesium alloy)
Ensure that the cathodic protection potential is maintained at -0.85V to -1.1V (relative to saturated calomel electrode)
Regularly test the uniformity of protection current distribution
3. Battery manufacturing standards
Select electrolytic copper foil with purity ≥99.99%.
Surface roughness is controlled at Ra≤0.3μm.
Maintain tensile strength in the range of 200-300MPa
Operation Precautions
Confirmation of polarity: the electrode connection must be checked with a multimeter before energizing.
Surface treatment: pickling and polishing are required to remove the oxidized layer before use.
Concentration monitoring: copper ion concentration in the electrolyte should be maintained at 80-120g/L.
Temperature control: Avoid exceeding 60℃, resulting in increased side reactions.
Safety protection: special protective equipment should be worn when operating cyanide-containing plating solution.
Future technology development trend
With the rise of new energy industry, copper electrode materials are developing in the direction of
composite. Graphene-coated copper collector can increase the energy density of lithium batteries by
15%, and the application of nanoporous copper structure in supercapacitors can increase the charging
and discharging efficiency by 30%. These innovative applications continue to expand the boundaries
of what is possible with copper materials.
Conclusion
Copper's role in electrochemical systems is characterized by a remarkable duality, a property that
makes it an irreplaceable functional material for industrial applications. Understanding its controllable
dissolution characteristics when used as an anode and its stable protective function when used as a
cathode is an important guide for optimizing production processes and improving product quality.
With the development of surface modification technology, this ancient metal is taking on a new life
and continues to promote the progress of electronic manufacturing, new energy and other fields.