In order to draw up a diagram of a galvanic cell, it is necessary to understand the principle of its action, structural features.
Consumers rarely pay attention to batteries and batteries, while these power sources are the most in demand.
Chemical current sources
What is a galvanic cell? Its circuit is based on an electrolyte. The device includes a small container where the electrolyte is located, adsorbed by the separator material. In addition, the scheme of two galvanic cells assumes the presence of a cathode and an anode. What is the name of such a galvanic cell? The scheme linking two metals together suggests a redox reaction.
The simplest galvanic cell
It implies the presence of two plates or rods made of different metals, which are immersed in a strong electrolyte solution. During the operation of this galvanic cell, an oxidation process is carried out on the anode, associated with the return of electrons.
At the cathode - recovery, accompanied byacceptance of negative particles. There is a transfer of electrons through the external circuit to the oxidizer from the reducing agent.
An example of a galvanic cell
In order to make electronic circuits of galvanic cells, it is necessary to know the value of their standard electrode potential. Let's analyze a variant of a copper-zinc galvanic cell that operates on the basis of the energy released during the interaction of copper sulfate with zinc.
This galvanic cell, the scheme of which will be given below, is called the Jacobi-Daniel cell. It includes a copper plate, which is immersed in a solution of copper sulphate (copper electrode), and it also consists of a zinc plate, which is in a solution of its sulfate (zinc electrode). The solutions are in contact with each other, but in order to prevent their mixing, the element uses a partition made of porous material.
Operation principle
How does a galvanic cell function, the circuit of which is Zn ½ ZnSO4 ½½ CuSO4 ½ Cu? During its operation, when the electrical circuit is closed, the process of oxidation of metallic zinc occurs.
On its contact surface with a s alt solution, the transformation of atoms into Zn2+ cations is observed. The process is accompanied by the release of "free" electrons, which move along the external circuit.
The reaction taking place on the zinc electrode can be represented as follows:
Zn=Zn2+ + 2e-
Recoverymetal cations is carried out on a copper electrode. Negative particles that enter here from the zinc electrode combine with copper cations, depositing them in the form of a metal. This process is as follows:
Cu2+ + 2e-=Cu
If we add the two reactions discussed above, we get a total equation that describes the operation of a zinc-copper galvanic cell.
Zinc electrode acts as anode, copper serves as cathode. Modern galvanic cells and batteries require the use of a single electrolyte solution, which expands the scope of their application, makes their operation more comfortable and convenient.
Varieties of galvanic cells
The most common are carbon-zinc elements. They use a passive carbon current collector in contact with the anode, which is manganese oxide (4). The electrolyte is ammonium chloride, applied as a paste.
It does not spread, so the galvanic cell itself is called dry. Its feature is the ability to “recover” during operation, which has a positive effect on the duration of their operational period. Such galvanic cells have a low cost, but low power. When the temperature drops, they reduce their efficiency, and when it rises, the electrolyte gradually dries out.
Alkaline elements involve the use of an alkali solution, so they have quite a lotapplications.
In lithium cells, an active metal acts as an anode, which has a positive effect on the service life. Lithium has a negative electrode potential, therefore, with small dimensions, such elements have a maximum rated voltage. Among the disadvantages of such systems is the high price. Opening lithium power sources is explosive.
Conclusion
The principle of operation of any galvanic cell is based on redox processes occurring at the cathode and anode. Depending on the metal used, the selected electrolyte solution, the service life of the element changes, as well as the value of the rated voltage. Currently, lithium, cadmium galvanic cells are in demand, which have a fairly long service life.
