Sintered nickel cadmium batteries

Charging of the vented sintered nickel-cadmium battery following its discharge in cyclic use, has four significant objectives. These may be stated as follows ... 

Potential hazards which may be present during the use and maintenance of the vented sintered nickel-cadmium battery fall into five general categories, as described in this section. 

Figure 31.38 shows the deerease in capacity with increasing discharge rate for rolled sintered nickel-cadmium batteries when discharged at 0 and —20°C after an initial charge at room temperature. Extremes of temperature adversely affect the performance of sealed nickel-cadmium batteries, especially below 0°C. This reduction in performance at lower temperatures is mainly due to an increase in internal resistance, and therefore, because of their inherently lower internal resistance, batteries incorporating sintered cells are normally recommended when lower operating temperatures are to be encountered. 

Figure 31.39 shows the relationship between the discharge rate and voltage of rolled sintered nickel-cadmium batteries when discharged at 0 and —20°C after an initial charge at room temperature. 

For many years, sintered-nickel electrodes have been used as the positive electrodes for sealed-type nickel-cadmium batteries. With an increase in the demand for high energy density, this type of elec-... 

Nickel salts are used in electroplating, ceramics, pigments, and as catalysts. Sinter nickel oxide is used as charge material in the manufacture of alloy steel and stainless steel. Nickel is also used in alkaline (nickel-cadmium) batteries. 

Nickel-cadmium batteries with thin sintered plates are used for on-board power supplies in aircraft, helicopters, tanks and military vehicles where their excellent low temperature, high rate performance is an important attribute. Modern 40 Ah cells designed for airborne use can deliver 20 kW of instantaneous power at 25°C and over 10 kW at —30DC. Again, the high cost of this system compared with that of lead-acid batteries has restricted its use. 

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.

Nickel cadmium batteries are extensively used in rechargeable portable electronic and electrical devices. Some efforts were made by DOE and others to produce higher energy density batteries based on sintered high surface area electrodes, but till now there has been no commercial success for this development program. 

In Japan, the Furukawa Battery Co., Ltd. industrialized a sintered-type vented nickel-cadmium battery for airplane starting in 1955. The Furukawa Battery Co., Ltd. started mass production of the vented-type nickel-cadmium secondary battery and a sealed nickel-cadmium secondary battery for industrial use in 1962 and developed the same to the fields, such as aircrafts. 

The specific heat Csatt of a battery depends on its specific design, but the different systems do not vary too much. In batteries with aqueous electrolyte, the content of water is of great importance due to its high specific heat. The specific heat of customary vented lead-acid batteries is slightly above lkj kg K while the corresponding value of VRLA batteries is in the range of 0.7 to 0.9 kJ kg K As the specific heat of a vented nickel/cadmium battery with sintered electrodes the value 1.25Jkg is reported (9), while that of the sealed version is... 

The memory effect—the tendency of a battery to adjust its electrical properties to a certain duty cycle to which it has been subjected for an extended period of time—has been a problem with nickel-cadmium batteries in some applications. Pocket, fiber, and plastic-bonded plate cells do not show this tendency. See Sec. 27.7.2 for a description of the memory effect with sintered-plate nickel-cadmium batteries. 

VENTED SINTERED-PLATE NICKEL-CADMIUM BATTERIES ... 

Typical average values for the energy and power densities of the vented sintered-plate nickel-cadmium battery at 25°C are shown in Table 27.2. 

FIGURE 27.12 Service life of typical vented sintered-plate nickel-cadmium battery (gravimetric) at 25°C. 

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