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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Battery. History of invention and production
Directory / The history of technology, technology, objects around us An electric battery is a reusable current source, the main specificity of which is the reversibility of internal chemical processes, which ensures its repeated cyclic use (through charge-discharge) for energy storage and autonomous power supply of various electrical devices and equipment, as well as for providing backup energy sources in medicine, manufacturing and other areas.
The discovery of the accumulative effect is one of the most important and significant inventions in the field of electrical engineering. Very often there was and is a need to supply electricity to devices or mechanisms in a place where there are no sources of energy. For a long time, a galvanic battery was used for these purposes, but it was a weak, expensive and excessively bulky current source. The creation of an electric battery greatly simplified this task. Back in 1802, Ritter discovered that two copper plates immersed in acid and connected to a galvanic battery are charged and can then be used as a constant current source for a short time. This phenomenon was later studied by many other scientists. In 1854, the German military doctor Wilhelm Sinsteden observed the following effect: when current was passed through lead electrodes immersed in dilute sulfuric acid, the positive electrode was covered with lead dioxide PbO2, while the negative electrode was not subjected to any changes. If such an element was then short-circuited, stopping the passage of current through it from a constant source, then a constant current appeared in it, which was detected until all the lead dioxide was dissolved in the acid. Thus, Sinsteden came close to creating an accumulator, but he did not draw any practical conclusions from his observation. Only five years later, in 1859, the French engineer Gaston Plante accidentally made the same discovery and built the first lead-acid battery in history. This was the beginning of battery technology. Plante's accumulator consisted of two identical lead plates wound on a wooden cylinder. They were separated from each other by a fabric gasket. Thus arranged, the device was placed in a vessel with acidified water and connected to an electric battery. A few hours later, by disconnecting the battery, it was possible to remove a sufficiently strong current from the battery, which retained its constant value for some time.
What explains the processes occurring in the battery? As in a galvanic cell, the electric current here is a consequence of a chemical reaction that can occur many times in both directions. Imagine that we start charging a dead battery by connecting it to a DC source. Usually, the still uncharged mass of the positive lead plate contains the remains of the previous cycle - lead oxide PbO and lead sulfate PbSO4, and the negative one contains only lead oxide PbO. Under the action of an electric current, the electrolyte - acidified water - begins to decompose: oxygen is released on the positive electrode, which immediately oxidizes lead oxide and lead sulfate to PbO2 peroxide (moreover, the acid residue SO4 goes into solution), and hydrogen is released on the negative plate. The latter combines with the oxygen of the oxide, forming metallic lead and water. The gas then begins to accumulate in the pores of the lead plate. If a charged battery is connected to a circuit, then the current passing through the battery during charging changes its direction. As a result, on the plate where oxygen was previously released, hydrogen begins to be released, which reacts with the oxygen of lead peroxide. On the other plate, oxygen is released. Sulfuric acid from the liquid passes to the positive electrode and again forms lead sulfate, while hydrogen and lead on the negative plate are oxidized, the first into water, the second into lead oxide. In a somewhat simplified form (without taking into account parallel processes), the chemical reaction of discharge has the form: PbO2 + Pb + 2H2S4 = 2PbSO4 + 2H2O. When charging, the phenomena go in the opposite direction. This reaction, accompanied by the release of an electric current, continues until the amount of lead oxide on both plates is balanced. The same reaction occurs in an open battery, but much slower. When charging (due to the release of an acid residue into the solution), the specific gravity of the liquid in the battery increases, and when discharged, it decreases (because when discharged, sulfuric acid combines with lead oxide and forms lead sulfate on the electrodes). During discharge, the energy of chemical reactions is converted into electrical energy, and during charging, vice versa. A significant drawback of the Plante battery was its small capacity - it discharged too quickly. Plante soon noticed that the capacity could be increased by special preparation of the surface of the lead plates, which should be as porous as possible. To achieve this, Plante discharged a charged battery, and then again passed a current through it, but in the opposite direction. This plate-forming process was repeated many times for about 500 hours and was intended to increase the lead oxide layer on both plates. Until the invention of the dynamo, batteries were of little interest to electrical engineers, but when it became possible to easily and quickly charge them with a generator, batteries became widespread. In 1882, Camille Faure greatly improved the technique of making accumulator plates. If the Plante accumulator began to work well only after repeated charging and discharging (until the plates became porous), in the Faure accumulator, the formation of plates occurred much faster. The essence of Faure's improvement was that he came up with the idea of covering each plate with red lead or other lead oxide. When charged, a layer of this substance on one of the plates turned into peroxide, while on the other plate, as a result of the reaction, a low degree of oxide was obtained. During these processes, a layer of oxides with a porous structure formed on both plates, which contributed to the accumulation of evolved gases on the electrodes. So that the mass of oxides formed on the plates does not fall off, they are covered with a cloth. The Faure battery not only charged faster than the Plante battery, but also had a much larger capacity and could produce a very strong current. It consisted of parallel lead plates placed close to each other and connected through one, so that each electrode of the same sign was placed between two electrodes of the opposite. Faure's invention immediately attracted the attention of electrical engineers. The German banker Volkmar, who took over the production of Faure batteries, soon improved them even more. In previous batteries, the oxide layer, as already mentioned, did not adhere well to the grate and easily fell off when shaken. This was a serious design flaw, as it prevented the use of batteries in transport. To improve the situation, Volkmar suggested making lead plates not solid, but in the form of gratings, the holes of which were stuffed with spongy lead. On such gratings, the active mass no longer simply stuck to the lead, but was firmly held in the cells.
At the beginning of the XNUMXth century, Edison took up the improvement of the battery, who wanted to make it more suitable for the needs of transport. In connection with this task, it was necessary to lighten the weight of the batteries, increase their capacity, get rid of poisonous lead and caustic sulfuric acid, which quickly corroded the lead plates, after which they had to be replaced. As usual, Edison set to work on a grand scale: he created a special laboratory with a large staff of chemists and entrusted them with research in all of the above areas. In essence, it was about creating a completely new type of battery, in which alkali served as an electrolyte, and crushed iron with some impurities served as a negative electrode. For a long time it was not possible to choose the material for the positive electrode. Since the chemical processes in the alkaline battery were very complex and not fully understood, we had to literally feel our way. In experimental models, the positive electrode was made from carbon, the pores of which were filled with various substances: many metals and their compounds were tried, but all of them gave insufficiently good results. Finally, we settled on nickel, which turned out to be the most suitable. So Edison came to the iron-nickel battery with an electrolyte in the form of caustic potash. (The chemical reaction that occurs during discharge in an alkaline battery is described in a somewhat simplified form by the equation: 2NiOOH + Fe + 2H2O = 2Ni(OH)2 + Fe(OH)2; when charging, the process goes in the opposite direction; electrolyte KOH, although it creates the necessary environment, does not participate in the reaction.) Several such batteries were made for extensive testing, and here the researchers were disappointed - the battery capacity turned out to be very small. Edison noticed that the purity of the material was of great importance in increasing capacitance. He ordered high-grade Canadian nickel for samples, after which the battery capacity immediately tripled. A small iron and nickel refinery was built in West Orange. The capacity of the new battery turned out to be 2 times greater than that of the old lead one. Edison claimed that this was the biggest advance in battery technology since its inception. Further experiments were so successful that in 1903 Edison decided to start industrial production of his batteries in a factory specially built for this. However, the first alkaline batteries that went on sale turned out to be very far from perfect: they did not hold a given voltage value well, often leaked, and had many other minor defects. Numerous complaints began to come in from distributors. Edison had to stop the plant and re-engage in improving his invention. Despite the setbacks, he continued to firmly believe in the success of the case. The refinement was entrusted to several groups at once: one worked on improving the welding of accumulator vessels, the other on the refining of iron, the third was engaged in nickel and additives to it. By 1905, more than 10 additional experiments had been carried out, and in 1910 a significantly improved battery was put back into production. In the first year, $1 million worth of products were produced, and all of them found good sales. The new portable battery soon became widespread in transportation, power plants, small boats and submarines. Author: Ryzhov K.V.
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