Cylindrical cells sealed nickel-cadmium batteries

Sealed nickel-metal hydride cells and batteries are constructed in cylindrical, button, and prismatic configurations, similar to those used for the sealed nickel-cadmium battery. 

Cylindrical, rectangular and button designs of sealed nickel-cadmium battery are available from most suppliers. These three types are available with compress and with sintered electrodes. Batteries with sintered electrodes have a very low internal resistance and a high load capacity which results in an improved power to size and weight ratio. These three types of nickel-cadmium cell are discussed in detail in Part 2. 

Figure 10.14 The construction of a cylindrical nickel/ cadmium battery. Key A, seal By positive terminal C, cell lid D, connection to positive plate E, cell case Fy positive plate G, separator H, sintered metal foil Iy negative paste Jy connection to negative plate. Diagram supplied by Berec Ltd.

Note The letter K always indicates a nickel/cadmium cell or a battery conforming to the specihcations of lEC Standard 60285, sealed nickel/cadmium cylindrical... 

Sealed nickel-cadmium cells and batteries are available in several constructions. The most common types are the cylindrical shaped batteries (see Table 28.3). Smaller button batteries and rectangular batteries are also manufactured. 

Figure 31.4 shows discharge curves for several cylindrical nickel-cadmium batteries of voltages between 6 and 14 V and capacities between 0.5 and 4 Ah. Figures 31.5 and 31.6, respectively, compare discharge curves for typical sealed nickel-cadmium cylindrical cells made using mass electrodes and sintered electrodes. 

Figure 31.20 illustrates the effect of battery temperature on capacity returned (discharged capacity) for 1.2V, 20 xAh and lAh capacity nickel-cadmium button cells. In both cases capacities start decreasing below 10°C and above 38°C. Similar plots comparing the performance of sealed nickel-cadmium button and cylindrical cells are shown in Figure 31.21. Figure 31.22 shows a typical plot of percentage withdrawable capacity versus temperature for a sealed nickel-cadmium sintered button cell. 

Nickel-cadmium sealed cells are now a commercially important consumer product. They find use, both as button and cylindrical cells, in portable cordless appliances such as power tools, electric razors and photoflash apparatus, and increasingly in hybrid mains/battery equipment such as portable tape recorders, radios and television receivers. Many of these cells are readily interchangeable with primary batteries. In recent years, advances in design have increased recharge rates cylindrical cells with sintered electrodes can now be fast charged from full discharge at up to the C/l rate of 80% of capacity. 

Button, cylindrical and prismatic sealed cells are similar in design to the starved-electrolyte configuration of nickel-cadmium cells. A schematic diagram of a six-cell battery is shown in Fig. 6.11. Because of the slightly... 

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