What is the source of electric current. Current source - classification and purpose. "dry" or "wet"
This article will describe methods for obtaining electric current, their types, advantages and disadvantages. In general terms, current sources can be divided into mechanical, chemical, and those using other physical transformations.
Chemical current sources
Chemical current sources convert the chemical reactions of the oxidizing agent and reducing agent into EMF. The first chemical current source was invented by Alessandro Volta in 1800. Subsequently, his invention was called "Volta's Element". Volt elements connected in a vertical battery make up the Volt column.
In 1859, the lead-acid battery was invented by the French physicist Gston Plante. It consisted of lead plates placed in sulfuric acid. This type of battery is still widely used, for example, in cars.
In 1965, the French chemist J. Leclanche proposed an element consisting of a zinc cup with an ammonium chloride solution, in which an agglomerate of manganese oxide with a carbon current lead was placed. This element became the progenitor of modern salt batteries.
All chemical elements are based on 2 electrodes. One of them is an oxidizing agent and the other is a reducing agent, both are in contact with the electrolyte. EMF occurs between the electrodes. At the anode, the reducing agent is oxidized, the electrons, passing through the external circuit to the cathode, participate in the reduction reaction of the oxidizing agent. Thus, the flow of electrons passes through the external circuit from the negative pole to the positive. Lead is used as a reducing agent. cadmium, zinc and other metals. Oxidizing agents - lead oxide, manganese oxide, nickel hydroxide and others. As an electrolyte - solutions of alkalis, acids and salts.
There are also fuel cells in which the oxidizer and reductant are supplied from outside. An example is a hydrogen-oxygen fuel cell, which works on the same principle as an electrolyzer, only in reverse - hydrogen and oxygen are supplied to the plates, and electricity is generated by the reaction of their combination into water.
Mechanical current sources
Mechanical current sources include all sources that convert mechanical energy into electrical energy. Usually not direct transformations are used, but by means of another energy, usually magnetic. So, for example, a magnetic field rotates in generators - created by magnets, or otherwise excited, acting on the windings, it creates an EMF.
E.Kh. Lenz discovered as early as 1833 that electric motors with permanent magnets could generate electricity if the rotor was spun. As part of the Jacobi electric motor testing committee, he empirically proved the reversibility of the electric motor. Later it was found that the energy generated by the generator can be used to power their own electromagnets.
The first generator was built in 1832 by inventors from Paris, the Pixin brothers. The generator used a permanent magnet, during the rotation of which an EMF was formed in the windings located nearby. In 1843, Emil Stehrer also built a generator consisting of 3 magnets and 6 coils. All early generators used permanent magnets. Later (1851-1867) electromagnets were used, powered by a built-in permanent magnet generator. Such a machine was created by Henry Wilde in 1863.
Also, the mechanical method can be attributed to an unused, but still existing method using piezoceramics. The piezo emitter is also reversible, and can generate energy under mechanical action.
Other current sources
The most used non-mechanical current source is the solar battery. The solar battery directly converts light into electricity by knocking out electrons in the pn junction with the energy of a photon. Silicon-based solar cells are the most commonly used. They are produced by doping the same semiconductor with various impurities to create np junctions.
Also, Peltier elements are often used in field conditions. The Peltier element creates a temperature difference when an electric current flows. The reverse effect, the Seebeck effect, is used to produce an electric current when a temperature difference is applied to the element. Due to the use of different conductors, the temperature of each is different, which leads to the flow of electrons from a hotter conductor to a less heated one.
current sources, devices that convert various types of energy into electrical energy. According to the type of energy being converted, I. t. can be conditionally divided into chemical and physical. Information about the first chemical I. t. (galvanic cells and accumulators) dates back to the 19th century. (e.g. Volta battery, Leclanchet element). However, until the 1940s 20th century in the world, no more than 5 types of galvanic pairs have been developed and implemented in designs. Since the mid 40s. As a result of the development of radio electronics and the widespread use of autonomous I. T., about 25 more types of galvanic pairs have been created. Theoretically, the free energy of chemical reactions of practically any oxidizing agent and reducing agent can be realized in an I. t., and, consequently, the realization of several thousand galvanic pairs is possible. The principles of operation of most physical I. t. were already known in the 19th century. In the future, due to the rapid development and improvement, turbogenerators and hydroelectric generators became the main industrial sources of electricity. Physical I. t., based on other principles, received industrial development only in the 50-60s. 20th century, which is due to the increased and rather specific requirements of modern technology. In the 60s. technically developed countries already had industrial samples of thermogenerators, thermionic generators (USSR, Germany, USA), atomic batteries
Chemical current sources It is customary to call devices that generate electric current due to the energy of redox reactions of chemical reagents. In accordance with the operational scheme and the ability to deliver energy to the electrical network, chemical generators are divided into primary, secondary, and reserve generators, as well as electrochemical generators.
Physical current sources called devices that convert thermal, mechanical, electromagnetic energy, as well as the energy of radiation and nuclear decay into electrical energy. In accordance with the most commonly used classification, physical I. t. include: electric machine generators, thermoelectric generators, thermionic converters, MHD generators, as well as generators that convert the energy of solar radiation and atomic decay
To maintain an electric current in a conductor, some external source of energy is needed, which would always maintain a potential difference at the ends of this conductor.
Such sources of energy are the so-called sources of electric current, which have a certain electromotive force, which creates and maintains a potential difference at the ends of the conductor for a long time.
Numerically, the electromotive force is measured by the work done by a source of electrical energy in the transfer of a single positive charge throughout a closed circuit.
If the energy source, doing work A, ensures the transfer of charge q throughout the closed circuit, then its electromotive force (E) will be equal to
Current source internal resistance- quantitative characteristic of the current source, which determines the amount of energy losses when passing through the source of electric current.
Internal resistance has the dimension of resistance and is measured in ohms.
When an electric current passes through a source, the same processes of energy dissipation occur, and when passing through a load resistance. Due to these processes, the voltage at the terminals of the current source is not equal to the electromotive force, but depends on the magnitude of the current, and, therefore, on the load. For small values of the current strength, this dependence is linear and can be represented as
8) Power and efficiency source is equal to the ratio of the voltage in the external circuit to the value of the EMF. Electric power- a physical quantity that characterizes the rate of transmission or conversion of electrical energy. Net power varies with external resistance in a more complex way. Indeed, Puseful=0 at extreme values of external resistance: at R=0 and R®¥. Thus, the maximum useful power should fall on the intermediate values of the external resistance.
9) Chemical current source (abbr. HIT) - a source of EMF, in which the energy of chemical reactions occurring in it is directly converted into electrical energy.
Principle of operation: The basis of chemical current sources are two electrodes (a negatively charged anode containing a reducing agent, and a positively charged cathode containing an oxidizing agent) that are in contact with the electrolyte. A potential difference is established between the electrodes - an electromotive force corresponding to the free energy of the redox reaction. The action of chemical current sources is based on the flow of space-separated processes with a closed external circuit: the reducing agent is oxidized on the negative anode, the resulting free electrons pass through the external circuit to the positive cathode, creating a discharge current, where they participate in the oxidizer reduction reaction. Thus, the flow of negatively charged electrons along the external circuit goes from the anode to the cathode, that is, from the negative electrode (the negative pole of the chemical current source) to the positive one. This corresponds to the flow of electric current in the direction from the positive pole to the negative, since the direction of the current coincides with the direction of movement of positive charges in the conductor.
In modern chemical current sources are used:
· as a reducing agent (anode material) - lead Pb, cadmium Cd, zinc Zn and other metals;
· as an oxidizing agent (cathode material) - lead (IV) oxide PbO 2 , nickel hydroxide NiOOH, manganese (IV) oxide MnO 2 and others;
· as an electrolyte - solutions of alkalis, acids or salts.
2) Manganese-zinc (MC) dry cells with a manganese dioxide depolarizer are widely used.
The dry element of the glass type (Fig. 3) has a zinc vessel of a rectangular or cylindrical shape, which is a negative electrode. Inside it is placed a positive electrode in the form of a carbon
sticks or plates, which is in a bag filled with a mixture of manganese dioxide with powdered coal or graphite. Charcoal or graphite is added to reduce resistance. A carbon rod and a bag with a depolarizing mass are called an agglomerate. The electrolyte is a paste composed of ammonia (NH4Cl), starch and some other substances. For glass elements, the central terminal is the positive pole.
Lead-acid batteries are the most common among secondary chemical power sources, having a relatively high power combined with reliability and relatively low cost. These batteries have a variety of practical applications. They owe their popularity and wide scale of production to starter batteries designed for various vehicles and, above all, cars. In this area, their monopoly position is stable and persists for a long time. On the basis of lead batteries, the vast majority of stationary and a significant part of car batteries are completed. Lead-acid batteries successfully compete with alkaline traction batteries.
leso-nickel battery- this is a secondary chemical current source in which iron is the anode, the electrolyte is an aqueous solution of sodium or potassium hydroxide (with the addition of lithium hydroxide), the cathode is nickel(III) oxide hydrate.
The active material is contained in nickel-plated steel tubes or perforated pockets. In terms of cost and energy density, they are close to lithium-ion batteries, and in terms of self-discharge, efficiency and voltage, they are close to NiMH batteries. These batteries are quite durable, resistant to rough handling (overcharging, deep discharge, short circuit and thermal shock) and have a very long service life.
Their use has declined since the 1914 Edison factory/laboratory fire stopped production, due to poor battery performance at low temperatures, poor charge retention, and high manufacturing costs comparable to the best sealed lead acid batteries and up to 1 /2 cost of NiMH batteries. However, due to the increase in the cost of lead in recent years, due to which the price of lead-acid batteries has risen significantly, prices have almost become equal.
When comparing batteries with lead-acid batteries, it should be remembered that the permissible operational discharge of a lead-acid battery is several times less than the theoretical full capacity, and iron-nickel is very close to it. Therefore, the real operational capacity of an iron-nickel battery, with an equal theoretical full capacity, can be many times (depending on the mode) greater than that of a lead-acid battery.
10) Electrical generators of direct and alternating current.
Machines that convert mechanical energy into electrical energy are called generators.
The simplest DC generator (Fig. 1) is a frame of a conductor placed between the poles of a magnet, the ends of which are attached to isolated half-rings, called collector plates. Positive and negative brushes are pressed against the half rings (collector), which are closed by an external circuit through an electric light bulb. For the generator to work, the conductor frame with the collector must be rotated. In accordance with the right hand rule, when the frame of the conductor with the collector rotates, an electric current will be induced in it, changing its direction every half a turn, since the magnetic lines of force on each side of the frame will intersect first in one direction, then in the other direction. At the same time, every half-turn, the contact of the ends of the conductor of the frame and the semi-rings of the collector with the brushes of the generator changes. In the external circuit, the current will flow in one direction, changing only in magnitude from 0 to a maximum. Thus, the collector in the generator serves to rectify the alternating current generated by the frame. In order for the electric current to be constant not only in direction, but also in magnitude (in magnitude - approximately constant), the collector is made of many (36 or more) plates, and the conductor is a lot of frames or sections made in the form of an armature winding .
Rice. 1. Scheme of the simplest DC generator: 1 - half ring or collector plate; I - conductor frame; 3 - generator brush
The principal device of the simplest alternating current generator is shown in fig. 4. In this generator, the ends of the conductor frame are each attached to their own ring, and the generator brushes are pressed against the rings. The brushes are closed by an external circuit through an electric bulb. When the frame with rings rotates in a magnetic field, the generator will give an alternating current that changes its magnitude and direction every half-turn. Such an alternating current is called single-phase. In technology, generators of three
From the course of physics, everyone knows that by electric current they mean the directed ordered movement of particles that carry a charge. To obtain it, an electric field is formed in the conductor. The same is necessary in order for the electric current to continue to exist for a long time.
Sources of electric current can be:
- static;
- chemical;
- mechanical;
- semiconductor.
In each of them, work is performed where differently charged particles are separated, that is, an electric field of a current source is created. Separated, they accumulate at the poles, at the points of connection of the conductors. When the poles are connected by a conductor, particles with a charge begin to move, and an electric current is formed.
Sources of electric current: the invention of the electric machine
Until the middle of the seventeenth century, a lot of effort was required to obtain electric current. At the same time, the number of scientists dealing with this issue has been growing. And so Otto von Guericke invented the world's first electric car. In one of the experiments with sulfur, it, molten inside a hollow glass ball, hardened and broke the glass. Guericke strengthened the ball so that it could be twisted. Rotating it and pressing a piece of skin, he got a spark. significantly facilitated the short-term supply of electricity. But more difficult problems could be solved only with the further development of science.
The problem was that Guericke's charges quickly disappeared. To increase the duration of the charge, the bodies were placed in closed vessels (glass bottles), and the electrified material was water with a nail. The experiment was optimized when the bottle was covered on both sides with a conductive material (sheets of foil, for example). As a result, they realized that it was possible to do without water.
Frog legs as a power source
Another way to generate electricity was first discovered by Luigi Galvani. As a biologist, he worked in a laboratory where they experimented with electricity. He saw how a dead frog's leg contracted when it was excited by a spark from a machine. But one day, the same effect was achieved by accident, when a scientist touched it with a steel scalpel.
He began to look for the reasons where the electric current came from. The sources of electric current, according to his final conclusion, were in the tissues of the frog.
Another Italian, Alessandro Volto, proved the failure of the "frog" nature of the current. It was observed that the largest current occurred when copper and zinc were added to the sulfuric acid solution. This combination is called a galvanic or chemical element.
But the use of such a means to obtain EMF would be too costly. Therefore, scientists worked on a different, mechanical, method of producing electrical energy.
How does a regular generator work?
At the beginning of the nineteenth century, G.Kh. Oersted discovered that when a current passed through a conductor, a field of magnetic origin arose. A little later, Faraday discovered that when the lines of force of this field cross, an EMF is induced in the conductor, which causes a current. EMF varies depending on the speed of movement and the conductors themselves, as well as on the field strength. When crossing one hundred million lines of force per second, the induced EMF became equal to one Volt. It is clear that manual conduction in a magnetic field is not capable of producing a large electric current. Electric current sources of this kind have shown themselves much more effectively by winding the wire on a large coil or producing it in the form of a drum. The coil was mounted on a shaft between a magnet and rotating water or steam. Such a mechanical current source is inherent in conventional generators.
Great Tesla
The brilliant scientist from Serbia, Nikola Tesla, having devoted his life to electricity, made many discoveries that we still use today. Multi-phase electrical electric motors, energy transfer through a multi-phase alternating current - this is not the whole list of inventions of the great scientist.
Many are sure that the phenomenon in Siberia, called the Tunguska meteorite, was actually caused by Tesla. But, perhaps, one of the most mysterious inventions is a transformer capable of receiving voltage up to fifteen million volts. Unusual is both its device and calculations that do not yield to known laws. But in those days they began to develop vacuum technology, in which there were no ambiguities. Therefore, the invention of the scientist was forgotten for a while.
But today, with the advent of theoretical physics, there is renewed interest in his work. The ether was recognized as a gas, to which all the laws of gas mechanics apply. It was from there that the great Tesla drew energy. It is worth noting that the ether theory was very common in the past among many scientists. Only with the advent of SRT - Einstein's special theory of relativity, in which he refuted the existence of the ether - was it forgotten, although the general theory formulated later did not dispute it as such.
But for now, let's take a closer look at the electric current and devices that are ubiquitous today.
Development of technical devices - current sources
Such devices are used to convert different energy into electrical energy. Despite the fact that physical and chemical methods for generating electrical energy were discovered a long time ago, they became widespread only in the second half of the twentieth century, when radio electronics began to develop rapidly. The original five galvanic pairs were replenished with 25 more types. And theoretically, there can be several thousand galvanic pairs, since free energy can be realized on any oxidizer and reductant.
Physical current sources
Physical current sources began to develop a little later. Modern technology made more and more stringent requirements, and industrial thermal and thermionic generators successfully coped with the increasing tasks. Physical current sources are devices where thermal, electromagnetic, mechanical and radiation and nuclear decay energy is converted into electrical energy. In addition to the above, they also include electric machine, MHD generators, as well as those used to convert solar radiation and atomic decay.
In order for the electric current in the conductor not to disappear, an external source is needed to maintain the potential difference at the ends of the conductor. For this, there are energy sources that have some to create and maintain a potential difference. The EMF of an electric current source is measured by the work performed when a positive charge is transferred throughout a closed circuit.
The resistance inside the current source quantitatively characterizes it, determining the amount of energy loss when passing through the source.
Power and efficiency are equal to the ratio of the voltage in the external electrical circuit to the EMF.
Chemical current sources
A chemical current source in an EMF electrical circuit is a device where the energy of chemical reactions is converted into electrical energy.
It is based on two electrodes: a negatively charged reducing agent and a positively charged oxidizing agent, which are in contact with the electrolyte. Between the electrodes there is a potential difference, EMF.
In modern devices are often used:
- as a reducing agent - lead, cadmium, zinc and others;
- oxidizer - nickel hydroxide, lead oxide, manganese and others;
- electrolyte - solutions of acids, alkalis or salts.
Dry elements made of zinc and manganese are widely used. A vessel made of zinc (having a negative electrode) is taken. A positive electrode is placed inside with a mixture of manganese dioxide with carbon or graphite powder, which reduces the resistance. The electrolyte is a paste of ammonia, starch and other components.
A lead acid battery is most often a secondary chemical current source in an electrical circuit, which has high power, stable operation and low cost. Batteries of this type are used in a variety of areas. They are often preferred for starter batteries, which are especially valuable in cars where they generally have a monopoly.
Another common battery consists of iron (anode), nickel oxide hydrate (cathode), and an electrolyte, an aqueous solution of potassium or sodium. The active material is placed in nickel-plated steel tubes.
The use of this species declined after the Edison factory fire in 1914. However, if we compare the characteristics of the first and second types of batteries, it turns out that the operation of iron-nickel can be many times longer than lead-acid.
DC and AC generators
Generators are devices that are aimed at converting mechanical energy into electrical energy.
The simplest DC generator can be represented as a frame of conductor, which is placed between the magnetic poles, and the ends are connected to insulated half rings (collector). For the device to work, it is necessary to ensure the rotation of the frame with the collector. Then an electric current will be induced in it, changing its direction under the influence of magnetic field lines. In the outer chain, it will go in a single direction. It turns out that the collector will rectify the alternating current that is generated by the frame. To achieve constant current, the collector is made of thirty-six or more plates, and the conductor consists of many frames in the form of an armature winding.
Consider what is the purpose of a current source in an electrical circuit. Let's find out what other sources of current exist.
current, current strength, current source
An electrical circuit consists of a current source, which, together with other objects, creates a path for the current. And the concepts of EMF, current and voltage reveal the electromagnetic processes occurring in this case.
The simplest electrical circuit consists of a current source (battery, galvanic cell, generator, and so on), energy consumers of electric motors, etc.), as well as wires connecting the clamps of the voltage source and the consumer.
The electrical circuit has an internal (power source) and external (wires, switches and knife switches, measuring instruments) parts.
It will work and have a positive value only if a closed circuit is provided. Any break causes the flow of current to stop.
The electrical circuit consists of a current source in the form of galvanic cells, electric accumulators, electromechanical and photocells, and so on.
Electric motors act as electrical receivers, which convert energy into mechanical, lighting and heating devices, electrolysis plants, and so on.
Auxiliary equipment are devices that serve to turn on and off, measuring instruments and protective mechanisms.
All components are divided into:
- active (where the electrical circuit consists of an EMF current source, electric motors, batteries, and so on);
- passive (which include electrical receivers and connecting wiring).
The chain can also be:
- linear, where the resistance of the element is always characterized by a straight line;
- non-linear, where the resistance depends on voltage or current.
Here is the simplest circuit, where a current source, a key, an electric lamp, a rheostat are included in the circuit.
Despite the widespread widespread use of such technical devices, especially in recent times, people are increasingly asking questions about installing alternative energy sources.
Variety of electrical energy sources
What sources of electricity still exist? It is not only the sun, wind, earth and tides. They have already become the so-called official alternative sources of electricity.
I must say that there are a lot of alternative sources. They are not common, because they are not yet practical and convenient. But who knows, maybe the future will be just behind them.
So, electrical energy can be obtained from salt water. Norway has already built a power plant using this technology.
Power stations can also operate on fuel cells with solid oxide electrolyte.
Piezoelectric generators are known that receive energy due to kinetic energy (footpaths, speed bumps, turnstiles and even dance floors already exist with this technology).
There are also nanogenerators that are aimed at converting energy in the human body itself into electrical energy.
And what about seaweed that heats houses, football swords that generate electricity, bicycles that can charge gadgets, and even finely cut paper used as a power source?
Huge prospects, of course, belong to the development of volcanic energy.
All this is the reality of today, over which scientists are working. It is quite possible that some of them will soon become completely commonplace, like electricity in homes today.
Or maybe someone will reveal the secrets of the scientist Nikola Tesla, and humanity will be able to easily receive electricity from the ether?
A current source is a device that converts various types of energy into electricity. Conventionally, such sources can be divided into physical and chemical.
Current source and its history
The first chemical galvanic cells and batteries appeared in the nineteenth century (Leclanchet cells and Volta batteries). However, until about the forties of the twentieth century, the advantages that the current source provided were not actually used. There were only a few galvanic pairs. But literally since the mid-forties, thanks to the rapid development of radio electronics, almost three dozen new types of pairs of galvanic cells have appeared. Theoretically, the current source is the realization of the free energy of almost any chemical reaction of a reducing agent and an oxidizing agent. Therefore, it is possible to implement more than a thousand galvanic pairs. The physical current source became widespread in industry in the early sixties of the last century. This is due to the specific requirements of technology in production. By the end of the sixties, most of the technically developed countries had thermogenerators, thermionic generators and atomic batteries.
Current source and its main characteristics
Technological progress has stimulated the development of power supplies, especially autonomous ones. The current source today can be found in portable lighting devices, radios, tape recorders, televisions, medical equipment, cars, airplanes, tractors, spacecraft and many other things. The main characteristics and parameters of power sources can be called: energy intensity, specific energy intensity, nominal and specific power, efficiency (efficiency), service life, reliability, frequency, overload capacity, voltage, rated current, cost.
Types of current sources
In accordance with the ability to accumulate energy, chemical sources are divided into primary, backup, secondary and electrochemical generators. There is also a current source on a field effect transistor. Each type should be considered in more detail.
Current source primary
Such sources allow only a single use of the chemical energy of the reagents. The cathode (positive electrode) and the anode (negative electrode) are separated in a liquid or pasty state by an electrolyte. Both the cathode and the anode are galvanically coupled.
Current source secondary
In such accumulators or rechargeable batteries, chemical energy is allowed to be used repeatedly, from hundreds of times to tens of thousands of cycles. The electrolyte and electrodes are constantly in a state of electrical contact with each other. To date, specific storage conditions for such batteries have been developed.
Backup current source
Although redundant sources allow only one cycle, the electrolyte and electrodes are not galvanically coupled. They are stored either in a liquid state (in metal or glass ampoules) or in a rigid solid state.
Electric current - how to create and maintain it
Electric current is the orderly movement of charged particles. To get an electric current in a conductor, you need to create an electric field in it. If a charged body is connected by a conductor to earth, then a short-term electric current arises in the conductor. In order to obtain and maintain an electric field in the conductor, apply electric current sources.
In any current source, work is done to separate positively and negatively charged particles. Separated particles accumulate at the poles of the source. An electric field is formed between the poles. If you connect them with a conductor, then the field appears in the conductor.
In an electric machine, the separation of charges is carried out with the help of mechanical energy. It then turns into electricity. In a thermoelement, internal energy is converted into electrical energy. Nuclear batteries convert nuclear energy into electrical energy.
A photocell converts light energy into electrical energy. Solar panels are made up of photovoltaic cells. They are used where light energy is the most accessible.
The energy of rivers, coal, oil, the atom is converted into electrical energy at power plants. The most common sources of electric current are galvanic cells and batteries.
Galvanic cells
A galvanic cell is a current source in which chemical energy is converted into electrical energy.
This is how the simplest galvanic element works.
The first galvanic cell was invented by Volt in 1799. From individual elements, he designed a battery, which they called the "voltaic column". In a galvanic cell, the electrodes must necessarily interact with the solution in different ways, so the electrodes are made from different materials.
The zinc plate in the Volta element is negatively charged, and the copper plate is positively charged.
And so the dry galvanic cell is arranged. Instead of a liquid, a thick paste is used in it:
A battery can be made up of several elements:
Light bulbs in electric lamps, as well as various other portable electrical appliances and children's toys, work from galvanic cells. When the electrodes in the galvanic cell are used up, I replace the cell with a new one.
Batteries
Batteries are chemical sources of electric current in which the electrodes are not consumed. The simplest battery consists of two lead plates immersed in a solution of sulfuric acid.
Such a battery does not yet give current. It must be charged before use. To do this, connect the poles of the battery with the same poles of any current source.
The current that goes through the battery during charging changes the chemical composition of its plates. The chemical energy of the battery increases.
Currently, nickel-cadmium and nickel-metal hydride batteries are also widely used. In aviation and space, silver-zinc batteries are used. New types of batteries: lithium-ion, lithium-polymer are used in mobile phones, tablets and other modern portable equipment.
Batteries are used in cases where it is more profitable to recharge the source of electric current than to replace it with a new one. In a car, the battery is used to start the engine and operate various devices. In space, the battery is charged by solar panels. Discharging, it feeds radio transmitters and equipment.