Different types of electrochemical cells convert their chemical energy into electrical current. They got their name in honor of the Italian scientist Galvani, who conducted the first such experiments and studies. Electricity is generated by the chemical interaction of two metals (usually zinc and copper) in an electrolyte.
Content
- Operating principle
- Varieties of elements
- Scope of application
Operating principle
Scientists placed copper and zinc plates in containers with acid. They were connected by a conductor, gas bubbles formed on the first, and the second began to dissolve. This proved that an electric current flows through the conductor. After Galvani, Volt took up the experiments. He created a cylindrical element that looks like a vertical column. It consisted of zinc, copper and cloth rings, previously impregnated with acid. The first element had a height of 50 cm, and the tension generated by it was felt by a person.
The principle of operation is that two types of metal in an electrolytic environment interact, as a result of which a current begins to flow through the external circuit. Modern galvanic cells and accumulators are called batteries. Their voltage depends on the metal used. The device is housed in a soft sheet metal cylinder. Grids with oxidation and reduction spraying act as electrodes.
The conversion of chemical energy into electricity eliminates the possibility of restoring the properties of batteries. Indeed, during the operation of the element, the reagents are consumed, due to which the current decreases. The reducing agent is usually a negative terminal from lithium or zinc. During operation, it loses electrons. The positive part is made from metal salts or magnesium oxide, it does the work of an oxidizing agent.
Under normal conditions, the electrolyte does not pass current; it decomposes into ions only when the circuit is closed. This is what determines the appearance of conductivity. An acid solution, sodium or potassium salts are used as the electrolyte.
Varieties of elements
Batteries are used to power appliances, devices, equipment, toys. All galvanic cells according to the scheme are divided into several types:
- saline;
- alkaline;
- lithium.
The most popular are saline batteries made from zinc and manganese. The element combines reliability, quality and reasonable price. But recently, manufacturers have been reducing or completely stopping their production, since the firms that produce household appliances are gradually increasing the requirements for them. The main advantages of this type of galvanic battery are:
- universal parameters that allow them to be used in different areas;
- easy operation;
- low cost;
- simple production conditions;
- available and inexpensive raw materials.
Among the disadvantages are a short service life (no more than two years), a decrease in properties due to low temperatures, a decrease in capacity with increasing current and a decrease in voltage during operation. When saline batteries are discharged, they can leak as the positive volume of the electrode pushes the electrolyte out. Conductivity is increased by graphite and soot; the active mixture consists of manganese dioxide. The service life directly depends on the volume of electrolyte.
The first alkaline elements appeared in the last century. The role of the oxidizing agent in them is played by manganese, and the reducing agent is zinc powder. The battery case is amalgamated to prevent corrosion. But the use of mercury was banned, so they were coated with mixtures of zinc powder with rust inhibitors.
The active substance in a galvanic cell device is these are zinc, indium, lead and aluminum. The active mass includes soot, manganese and graphite. The electrolyte is made from potassium and sodium. The dry powder greatly improves the performance of the battery. With the same dimensions as in salt species, alkaline ones have a large capacity. They continue to work well even in severe frost.
Lithium cells are used to power modern technology. They come in the form of batteries and accumulators of different sizes. The former contain a solid electrolyte, while other devices contain a liquid electrolyte. This option is suitable for devices that require a stable voltage and medium current charges. Lithium batteries can be charged multiple times, batteries are used only once, they are not opened.
Scope of application
A number of requirements are put forward for the production of electrochemical cells. The battery case must be reliable and sealed. The electrolyte must not leak out, and foreign substances must not be allowed to enter the device. In some cases, when liquid flows out, it lights up. A damaged element cannot be used. The dimensions of all batteries are practically the same, only the dimensions of the batteries differ. Elements can be of different shapes: cylindrical, prismatic or disc.
All types of devices have common advantages: they are compact and lightweight, adapted to different ranges of operating temperature, have a large capacity and work stably in different conditions. There are also some disadvantages, but they apply to certain types of elements. Salt ones do not last long, lithium ones are designed in such a way that they can ignite when depressurizing.
The applications for batteries are numerous:
- digital technology;
- Kids toys;
- medical devices;
- defense and aviation industry;
- space production.
Electrochemical cells are easy to use and affordable. But some species need to be handled carefully and not used if damaged. Before purchasing batteries, you need to carefully study the instructions of the device that they will power.
