The first electric battery was given to known to the world by Volta in 1800, in a letter sent to President Royal Society of London. It was a series of pairs of discs (stacked) of zinc and copper (also silver), separated from each other by pieces of cardboard or felt impregnated with water or brine, which measured about 3 cm in diameter. When you set a unit of measure for the potential difference, the volt (just in honor of Volta) might know that each of these elements provides a voltage of 0.75 V or so, but none of these concepts was available then. His stack connected in series to increase voltage allowed at will, another discovery of Volta. The invention was an absolute novelty and enjoyed immediate success and well-deserved, and that initiated the electric age we currently live, allowing precise experimental study of electricity, surpassing the huge limitations that had to do electrostatic generators, the only previously available. Another provision also used and described by Volta to the device consisted of a series of glasses of liquid (side by side, on drums), in which they dipped the strips of metal, a metal connecting externally with another.
immediately began to get around Europe and America many tests with various liquids, metals and regulations, trying to improve the characteristics of the original device, which rarely achieved, but which resulted in a myriad of different types of batteries, of which no memory has been more that of the more remarkable.
The Daniell cell, which was released in 1836 and which have been widely used after certain design variations, consists of a zinc electrode immersed in a zinc sulfate solution and a copper electrode immersed in a concentrated solution of sulphate copper. Both electrolytes are separated by a porous wall to avoid direct reaction. In this situation the tension of the dissolution of zinc is greater than the pressure of Zn + + ions and the electrode dissolves, releasing Zn + + and being negatively charged, a process in which electrons are released and that is called oxidation. In the copper sulfate solution, due to its high concentration of Cu + +, Cu is deposited on the metal electrode which is thereby positively charged through a process called reduction, which involves the incorporation of electrons. This battery has a potential difference of between 1.07 and 1.14 V between the electrodes. Its great advantage over others of his time was the constancy of the voltage generated due to elaborate arrangement that facilitates the depolarization, and the reserve of electrolyte, which helps keep your concentration for longer.
Battery Grove (1839) used as depolarizer acid Nitric NO3H. Its electromotive force is from 1.9 to 2.0 V Originally used platinum for the anode, but Cooper and Bunsen then replaced it with coal, the zinc cathode was treated with mercury. It was prized for its stability and greater energy, despite the great inconvenience posed by the release of corrosive fumes. Grove himself in the same year and developed a battery that produces electricity through the recombination of hydrogen and oxygen, which is the precedent of the contemporary genre known as fuel cells.
Leclanché Battery (1868) uses a solution of ammonium chloride is immersed in the zinc electrodes and coal, the latter surrounded by a paste of manganese dioxide and carbon dust and depolarizing. Provides a voltage of 1.5 V and its main advantage is that it stores well, because zinc is not attacked only when power is removed the item.
This type of battery was the basis for the important advance was the so-called dry stack, which owns almost all used today. The types so far described were referred to as wet as they contained liquid, which not only made transport problem, but they used to deliver hazardous gases and unpleasant odors. Dry batteries, however, consisted of a cylindrical vessel zinc, which was negative, filled with an electrolytic paste and a carbon rod in the center (positive electrode), all sealed to prevent leaks. Previously there had been another type of dry cells, such as the Zamboni (1812), but were purely experimental devices that do not provide any useful current. The dryness is relative, firstly because strictly dry element would not provide any electricity, so that what is inside the battery is a gel or paste, as moisture makes every effort to conserve resources, but also because use and over time tend to corrode the contender, so that the battery may shed part of its electrolyte abroad, where you can attack other metals. For this reason it is recommended to remove them when not in use for a long time or when they have worked hard. This problem is highly attenuated in the products of the late twentieth century through the use of stainless steel containers, but still occurs sometimes.
important in another sense have been the standard battery, for calibration purposes and determination of units, and battery Clark (1870), zinc and mercury, whose voltage was 1.457 V, and the stack Weston (1891), of cadmium and mercury, 1.018 V. These tensions are measured in vacuum, ie without any external load connected, and a constant temperature 20 ° C.
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