Internal resistance zinc-carbon cells

Production lines typically operate at upwards of 500 cells/min or more. The alkaline cell has higher energy storage, longer shelf life, and lower internal resistance than either of the two carbon-zinc cells. The alkaline cells are also produced in coin/button cell configuration as shown in Figure 10.7. 

In the zinc chloride cell, precipitated basic zinc chloride is the primary anode product because of the low concentration of ammonium chloride in the cell. Water and zinc chloride are consumed in equations 1 and 7 and must be provided in adequate amounts for the cell to discharge efficiently. Usually more carbon is used in zinc chloride cells than in Leclanchn cells in order to increase the electrolyte absorptivity of the cathode and thus allow the use of a larger volume of electrolyte. Also, the use of a thin paper separator, which decreases internal resistance, allows less space for water storage than the thick, pasted separator construction traditionally used in Ledanchit cells. 

The internal resistance of zinc chloride (and carbon-zinc) cells increases with storage time, use and decreasing temperature. Table 7.1 compares the approximate internal resistance, as determined by flash currents of several types of round cell of the carbon-zinc and zinc chloride types. 

This traditional dry cell consists of a carbon-rod cathode (positive terminal) immersed in a moist paste of Mn 02, Zn Cl2, NH4CI, and powdered carbon, which is contained in a metallic zinc-can anode (negative terminal). The voltage (without load) of these cells is about 1.6 V, which have limited shelf life because of corrosion of the zinc can and increased internal resistance. 

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