Leclanche advantages

The Leclanche dry cell with zinc replaced by magnesium offers considerable advantages. In the electromotive series, magnesium occupies a more basic position as compared to zinc ( n = -0.76 V / g = -2.38 V), and this means that the voltage of a magnesium cell is greater than that of a similar zinc cell. 

This type of cell is another variant on the basic Leclanche cell. In this case, the electrolyte is a concentrated aqueous solution of potassium hydroxide (about 30%), partly converted to potassium zincate by the addition of zinc oxide. The main advantage of alkaline manganese cells over Leclanche cells is their relatively constant capacity over a wide range of current drains and under severe service schedule conditions. Another feature of this system is that it can be the basis of a secondary battery system. The cell reaction may be written formally as... 

The advantage of the latter system with respect to the Leclanche battery is closely related to the electrolyte insoluble reaction products are less involved and this results in an operating temperature that ranges further down the scale, and higher current densities. 

Most lithium battery systems show a cell voltage in the upper range of 1.5 to 4.0 V or even higher. This alone is an advantage with regard to the energy density and specific energy of those cells. So in many cases only one lithium cell suffices where otherwise two or three conventional Leclanche or alkaline cells are necessary. 

TABLE 8.2 Major Advantages and Disadvantages of Leclanche and Zinc-Chloride Batteries... 

Both the Leclanche and zine-ehloride batteries have performance eharaeteristies that show advantages in specific applications, but poor performance in others. A variety of faetors influence battery performance (see Chap. 3). It is necessary to evaluate speeifies about the application (discharge conditions, cost, weight, etc.) in order to make a proper selection of a battery. Many manufacturers provide data for this purpose. 

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