Battery - SpeedyLook encyclopedia

Principle

The case of a pile shelters a chemical reaction between two substances of which one can yield easily electrons (reducing material), and the other which absorbs them (material oxidizing). Such a reaction is called a oxydoreduction.

Each element of the oxidizing/reducing couple is connected to a electrode. These electrodes, when they are connected to a electric Consommateur, cause the circulation of a Electric current; the chemical reaction causes a circulation of loads (electron S, Ion S). A pile thus provides D.C. current.

the terminal (-) of a pile corresponds to the Anode where the reaction of Oxydation occurs which will provide the electrons.
the terminal (+) of a pile corresponds to the Cathode where the reaction of reduction occurs which will consume the electrons.

This system is used for the batteries and the accumulator batteries, with various electrochemical couples. A battery can contain several of these couples assembled in series, which makes it possible to increase the tension available at the boundaries of the pile.

It is possible to produce an artisanal pile, for example by pricking in a lemon a trombone unfolded (out of steel) and a stripped electric wire (out of copper) connected to a small lamp or a quite selected electroluminescent diode. One finds in the trade of the gadgets which use this principle: for example of the small crystal controlled quartz clocks which are fed by a potato.

History

There exist archaeological artefacts resembling piles. It is for example the case of the Battery of Baghdad which is dated between - 250 and + 250. The assumption making of these objects of the batteries, although plausible, remains however not proven and is thus discussed. There in addition does not exist any historical link between these objects and the development of the contemporary piles.

In 1786, Luigi Galvani, observes that the muscles of a frog thigh contract when it is put in contact with metals, same manner as when one connects it on an electrostatic machine. He discovers that the reaction is stronger when one uses an instrument made up of two different metals.

In opposition with work of Galvani (electricity of animal origin), Alessandro Volta invents the first pile with column on March 17th 1800 (publication submitted on March 20th, 1800 in a French letter to the president of the Royal Society, Joseph Banks); these first systems consisted of a “stacking” of discs of two different metals separated by felt discs, soaked with Acide, from where the name of the invention. The pressure of the column on the discs of bottom causes a draining of the felt cylinders which end up more not filling their office. Volta thus invents quickly the Pile with crown, consisted of smaller stackings assembled in series. Since 1802 William Cruikshank creates the Pile with trough by vertically laying out copper and zinc the blades in an insulating wall vat filled with acidulous water. It is much simpler to produce than the pile of Volta.

A few days after the invention of Alessandro Volta, two chemists British, (1753-1815) and (1768-1840) use the pile of Volta to carry out the first electrolysis (electrolysis of water) on May 2nd 1800.

Polarizable piles

Between 1813 and 1815, William Hyde Wollaston develops the Pile Wollaston in which the copper electrode surrounds the electrode of zinc. That makes it possible to double the surface of the electrode and to prolong the operation of the pile. These first piles suffer indeed from a malfunction: polarization.

The reaction of oxydoreduction causes an accumulation of by-products which disturbs the operation of the pile. In these piles zinc-copper it is the reduction of the acid of the electrolyte which produces a release of hydrogen bubbles on the copper which prevents the passage of the current. At the end of a certain time, it is thus necessary to clean the pile of these deposits so that it continues to function.

In 1813, Napoleon provides to the Polytechnic school a voltaic pile of 600 zinc and copper couples, occupying 54 square meters of surface. Humphry Davy makes build a Cruikshank pile made up of 200 troughs and 2.000 couples at the Royal institute of London. With these monumental piles it was possible to obtain intensities of 10 amps, that is to say powers about ten kw.

Impolarizable piles

In these piles the products of the reaction of oxydoreduction used do not deteriorate the electrochemical properties of the unit.

In 1829, Antoine Becquerel creates the first pile with two liquids separated by locking up the zinc plate in acid solution in an ox large intestine, which separates it from the copper electrode placed in a copper sulfate bath. The generation of hydrogen is replaced by an accumulation of copper on the walls of cathode.

The principle is improved in 1836 by John Frederic Daniell which replaces the ox intestine by a porous ground vase. The Pile Daniel is the first to offer a durable source of energy. On the principle of the pile Daniel, one will create several technological improvements thereafter as the piles Callaud which will be used by the telcos in the years 1860.

Johann Christian Poggendorff invents in 1842 the pile with bichromate: it releases from the oxygen which recombines with hydrogen responsible for polarization. Created in 1850, the Pile Grenet is a pile with only one liquid, with zinc and carbon electrodes amalgamated (plunged in mercury) in an electrolyte of sulphuric acid and potash bichromate. When the pile was not used, it was however necessary to withdraw the zinc electrode of the solution to preserve it. Various improvements (Pile Found, Pile Chardin, Pile Neighbor and Dronier…) will follow to insulate this electrode.

These piles bottles will be used until the beginning of the 20th century: the power and the high tension of the piles to bichromate were appreciated a long time at the laboratory. They were used little like crushes domestic because of the toxicity of bichromate and the problems of maintenance of the electrode.

Piles with depolarization

These piles use a reducer to eliminate the products from reaction which are formed with cathode.

The first pile with depolarization is invented in 1838 by William Robert Grove. It replaces copper by platinum and uses nitric acid (named nitric acid at that time). It obtains a powerful pile but expensive because platinum is a rare metal. In 1843 Robert Wilhelm Bunsen replaces platinum by coal what reduces the costs notably. But nitric depolarization involves a toxic vapor release which returns the use of these piles malcommode.

In 1867, Georges Leclanché creates the first solid depolarizer pile: the Dioxide of manganese. The Pile Leclanché is less powerful than the pile bottle but does not require any maintenance (it “does not wear that if one makes use of it” as will say the publicity of the Wonder pile). In 1888 Carl Gassner invents the dry cell by gelling the ammonium chloride solution with Agar-agar. With some improvements, this dry cell is always used today.

Samuel Ruben and Philipp Rogers Mallory creates the Pile with mercury during the Second world war. The first alkaline Pile general public will be designed by Lewis Urry in 1959 for Union Carbide.

In 1970, the first piles with lithium, which make it possible to replace zinc by a more reducing metal, are developed. They are marketed in 1977.

Piles were used as references to define a standard of tension before being détrônée by a measurement based on the Effet Josephson: the Pile Daniel, then the Cellule of Clark invented in 1872 by Josiah Latimer Clark was employed until 1905, then it was replaced by the Cellule of Weston until 1972.

Concentration cells

There also what is called exist concentration cells which are electrochemical devices like the piles (two solutions and a saline bridge) which draw their energy from the difference in concentration of an aqueous solution from one solution to another. The solutions and the anodes are very in the same way standard. It is a simple method to manufacture electricity. This model of pile intervenes especially in metallurgical industry on the level of the Galvanisation and the study of the Corrosion.

Types of piles

The majority of the voltaic cells are limited to 1,5 V, because of the electrochemical potentials their components. The cells containing lithium can provide higher power (up to 3 volts).

Formats

The capacity of a pile is often expressed in ampere-hours (1 Ah = 3600 coulombs). If a pile can provide an amp (1 A) of current during one hour, it have a capacity of 1 Ah. If it can provide 1 has during 100 hours or 2 has during 50 H, etc, its capacity is of 100 Ah. It is directly dependant on the quantity of electrolyte and electrode in the pile.

The capacity of a pile also depends on other factors like the intensity of the current, the utilization period, the temperature, etc the manufacturers of batteries thus employ a standard method to evaluate their piles. The Loi of Peukert models the capacity of a pile according to the output current.

The format of the batteries is standardized by the international electrotechnical Commission (CEI) and by the American National Standards Institute (ANSI). Although standard CEI became a standard, a certain number of names specific to the manufacturers of piles remains. The correspondence between the various formats is accessible here: commercial Naming of the piles and electric fencers.

Note: in classification CEI, R represents piles zinc-carbon, LR the alkaline piles, RC the accumulators. Other technologies are generally written in all letters on packing.

Technologies

Since December 1998, the piles with mercury are prohibited in Europe (directive 98/101/CE) and with the the United States for environmental problems. There thus exist three large Technologie S of piles general public:

“alkaline” Pile 1,5 V (⊝ Zn/Zn (OH) 4 ² ¯/K+ + OH¯/MnO (OH)/MnO2/C ⊕).
Pile “saltworks carbon-zinc” 1,5 V. For apparatuses with weak needs (⊝ Zn/Zn ² +/NH4+ + Cl¯/MnO (OH)/MnO2/C ⊕).
Pile “lithium 1,5 V” (also called L91). It is likely to explode if one tries to reload it, able to maintain very a long time the tension electric.
One finds also piles with oxide of money (certain piles buttons for watches) or of the piles air-zinc (used in particular in the hearing aids) (⊝ Zn/ZnO // Ag2O/Ag/C ⊕).

Use of the piles

On average the batteries are thrown whereas they still have a third of energy usable. Indeed, the electronic devices (numerical camera, reader MP3, etc) need a minimal tension to function, but the tension of the piles drops during their discharge. Such piles (alkaline or coal-zinc) can then still be used to feed from the less demanding apparatuses (alarm clock, toy, flashlight, operate by remote control, etc).

The performance of a whole of piles is that of its weakest element. Moreover, if an element were charged than the others, he would be traversed by an electric current because of the other piles (what would amount charging it with back and would become dangerous). It is thus necessary to change all the piles at the same time and to use similar models.

In general all the piles discharge during time, even if they are not used. There exist technologies of piles activables which make it possible to delay the starting of the reaction. They for example are used in the safety members (airbag, marks out of distress of boat, etc) or in certain military applications.

Recycling

The piles are waste dangerous. They contain metals (Nickel - Cadmium - mercury - Plomb - Fer - Zinc - Lithium) of which some are toxic and harmful for the environment. Lead and mercury, in particular, are poisons for the human ones and the animals. The piles should not be thrown in an ordinary dustbin, but paid in a point of collection.

In France, the salesmen who market piles and batteries are held to take them again free once worn. The piles must then be developed or eliminated. In Switzerland, an inclusive of tax in the selling price finances the recycling of the piles. In Belgium, approximately 70% of the piles were collected in 2000. In France in 2006, nearly 9.000 tons were collected and recycled according to Ademe.

The Recyclage makes it possible to recover reusable metals (Fer, Manganèse, Zinc and mercury mainly). But the piles are not which can be recycled with 100 %, and residual slags must be deposited in décharges.22. Rate of recycling in 1999:55% against 35% in 1998 (new process for the piles saltworks and alkaline). This rate is based on the rough total weight of the collected piles. 15% to 18% of the weight of the piles consist of water.

Incineration (thermal valorization): 10%

Market

In 2004,875 million piles were sold in France (alkaline 75%, saltworks 22%, refillable 2%), 100 million in Belgium in the year 2000

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