LeclanchS cell

Salmiak, m. sal ammoniac (ammonium chloride). -clement, n. Elec.) sal ammoniac cell, Leclanch cell, -geist, m. aqueous ammonia, -kristall, m. (crystallized) sal ammoniac, -lakritze, /. sal ammoniac-licorice pastilles. -Idsung, /. ammonium chloride solution, -salz, n. sal volatile (ammonium carbonate) ... 

The zinc chloride cell, which was first patented in 1899, IS actually an adaptation of the Leclanche cell. The major innovation was the development of plastic seals that permitted the replacement of animoliitim chloride in the electrolyte. 

Cross-section of a Leclanche cell battery. (Gale Group, Inc.)... 

No gas is produced. The alkaline dry cell, although more expensive than the Leclanche cell, has a longer shelf life and provides more current. 

Le Chatelier s principle A relation stating that when a system at equilibrium is disturbed it responds in such a way as to partially counteract that change, 337-338 buffers and, 385 compression effects, 339-340 expansion effects, 339-340 precipitation equilibrium, 442 reaction conditions, 348q temperature changes, 340 Lead, 2,501 Leclanch cell, 500 Leucine, 622t... 

Figure 1 shows the principal Zn-carbon (Leclanche) cell and Figure 2 shows the basic construction of a cylindrical AA-size alkaline Zn - Mn02 cell. 

Figure 1. The design principle of a cylindrical Zn-carbon (Leclanche) cell [21. I, Zinccan 2, separator MnO, bobbin (Reproduced by courtesy of Varta Battery AG).

Zn - Mn02 batteries [2] dominate the world s small-format battery industry. In 1995 Zn-carbon batteries (the carbon rod in the center of Leclanche cells is the reason for this name) comprised 67 percent of the world market, and the other 33% belonged to alkaline cells (Table 1). 

Leclanche cells can be assumed. The accuracy of the total capacity calculations is not better than 10 percent due to temperature and other variations, but the economy of recharging is clear. 

The "classical" Leclanche cell uses zinc sheet formed into a cylindrical can serving simultaneously as the anode and as the cell container (AB1C1). The cathode is a mixture of Mn02 and graphite wrapped into a piece of separator and contacted by a central carbon rod. The can dissolves slowly when the cell is not in use and faster when the cell delivers electrical energy. The reaction following the primary electrochemical zinc dissolution [Eq. (19)] leads, in the case of an ammonium chloride electrolyte, to a zinc diammine cation ... 

The alkaline version of the Mn02 / zinc cell follows a different concept because it turns the construction of the Leclanche cell completely around now the cathode (Mn02 + carbon) forms a hollow cylinder contacting the inner wall of the cell container (steel) along its outer surface. The inner cavity has to accommodate anode, electrolyte, separator, and current collector. Usually, the separator forms a basket, which is automatically inserted and pre-... 

Perhaps the first practical application of carbonaceous materials in batteries was demonstrated in 1868 by Georges Le-clanche in cells that bear his name [20]. Coarsely ground MnO, was mixed with an equal volume of retort carbon to form the positive electrode. Carbonaceous powdered materials such as acetylene black and graphite are commonly used to enhance the conductivity of electrodes in alkaline batteries. The particle morphology plays a significant role, particularly when carbon blacks are used in batteries as an electrode additive to enhance the electronic conductivity. One of the most common carbon blacks which is used as an additive to enhance the electronic conductivity of electrodes that contain metal oxides is acetylene black. A detailed discussion on the desirable properties of acetylene black in Leclanche cells is provided by Bregazzi [21], A suitable carbon for this application should have characteristics that include (i) low resistivity in the presence of the electrolyte and active electrode material, (ii) absorption and retention of a significant... 

The studies by Biermann et al. [28] indicate that the carbon blacks used as the conductive matrix in Leclanche cells remain chemically inert, that is, they do not undergo oxidation during storage or discharge of the cell. However, Caudle et al. [29] found evidence that the ion-exchange properties of carbon black, which exist because of the presence of surface redox groups, are responsible for electrochemical interactions with Mn02. The extent of MnO, reduction to MnOOH depends on the carbon black (i.e., furnace black > acetylene black). 

FIGURE 12.21 A commercial dry cell. The dry cell is also called the Leclanche cell, for Georges Leclanche, the French engineer who invented it in about 1866. The electrolyte is a moist paste. 

The Leclanche cell (also known as the dry cell) is frequently used to power flashlights, watches, calculators, and a number of other portable devices. Despite the name dry cell, this battery does contain an electrolyte solution but only in the form of dense paste. There are two versions of this cell, the acid version and the alkaline version. 

Table 6.12 Some modified versions of Leclanche cells.

There are several types of battery we can envisage. A majority of the batteries we meet are classed as primary batteries, i.e. a chemical reaction occurs in both compartments to produce current, but when all the chemicals have been consumed, the battery becomes useless, so we throw it away. In other words, the electrochemical reactions inside the battery are not reversible. The most common primary batteries are the Leclanche cell, as described below, and the silver-oxide battery, found inside most watches and slim-line calculators. 

The Leclanche cell was first sold in 1880, and is still probably the most popular battery in the world today, being needed for everyday applications such as torches, radios, etc. It delivers an emf of ca 1.6 V. 

Alkaline manganese cells are broadly similar in design to the Leclanche cell, but they contain concentrated KOH as the electrolyte instead of NH4CI. 

A dry cell is a galvanic cell with the electrolyte contained in a paste thickened with starch. This cell is much more portable than the Daniell cell. The first dry cell, invented by the French chemist Georges Leclanche in 1866, was called the Leclanche cell. 

Modern dry cells are closely modelled on the Leclanche cell, and also contain electrolyte pastes. You have probably used dry cells in all kinds of applications, such as lighting a flashlight, powering a remote control, or ringing a doorbell. Dry cells are inexpensive. The cheapest AAA-, AA-, C-, and D-size 1.5-V batteries are dry cells. 

Traces of water are thought to cause the formation of a film on the anode in the Li/dimethyl sulfite system (25). By 1973 there were advertisements that primary Li-organic (Li/S02) cells were commercially available (26), and indeed in 1978 they are available from a number of manufacturers. Even a D-size Li-CuS cell with a mixed nonaqueous solvent is superior to the aqueous Leclanche cell of the same size, according to the authors of (27). 

---