Nickel-cadmium battery sealed batteries

Focusing on the concept of the completely sealed system, the Sanyo Electric Co. developed sealed-type nickel-cadmium batteries in 1961. This type of battery enjoys a wide application range that is still expanding a large variety of nickel-cadmium batteries has been developed to meet user needs ranging from low-current uses like emergency power sources and semiconductor memories to high-power applications such as cordless drills. 

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-... 

Engineering Handbook of Sealed Type Nickel-Cadmium Batteries, Sanyo Electric Co., Ltd., Osaka, 1988. 

Lead hydroxide is used in making porous glass in electrical-insulating paper in electrolytes in sealed nickel-cadmium batteries in recovery of uranium from seawater and as a catalyst for oxidation of cyclododecanol. 

Fig. 6.7 Nominal 6 V sealed nickel-cadmium battery formed by connecting five cells in scries, (By courtesy of Varta.)...

It must be emphasized that the most appropriate charging regime is very dependent on the cell system under consideration. Some are tolerant to a considerable amount of overcharging (e.g. nickel-cadmium batteries), while for others, such as zinc-silver oxide and most lithium secondary cells, overcharging can result in permanent damage to the cell. Sealed battery systems require special care float charging should not be used and trickle charge rates should be strictly limited to the manufacturer s recommended values, since otherwise excessive cell temperatures or thermal runaway can result. 

Refs. [i] Crompton TR (2000) Battery reference book, 3rd edn. Buttersworth-Heinemann, Oxford, 9/8, 30/3,47/11 [ii] Linden D (1994) Factors affecting battery performance. In Linden D (1994) Handbook of batteries, 2nd edn. McGraw-Hill, New York, pp 3.5-3.11 [Hi] Carcone JA (1994) Sealed nickel-cadmium batteries. In Linden D (1994) Handbook of batteries, 2nd edn. McGraw-Hill, New York, pp 28.1-33.35... 

Maintenance-free battery— A rechargeable - battery that does not require replenishing of water during its service life. Usually the term refers to maintenance-free -> lead-acid and sealed nickel-cadmium batteries, which, in contrary to the conventional ones, are designed to suppress water loss due to -> electrolysis (overcharging) and evaporation. 

For small-size portable rechargeable batteries, the collection of spent nickel cadmium batteries started in 1985 and has been pursued in combination with the collection of nickel metalhydride batteries, lithium ion batteries and small-size sealed lead-acid batteries. The collection rate of nickel cadmium batteries was over 40% in 2000. 

An Act To phase out the use of mercury in batteries and provide for the efficient and cost-effective collection and recycling or proper disposal of used nickel cadmium batteries, small sealed lead-acid batteries, and certain other batteries, and for other purposes. 

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.

Cadnica sealed type Nickel-Cadmium batteries engineering handbook, Sanyo Electric Company, Osaka... 

W.R.C Scott, D.W. Rusta, Sealed-Cell Nickel Cadmium Battery Application Manual, NASA Reference Publication 1052, Dec 1979. 

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. 

However, the pocket-type nickel-cadmium battery has low energy density and low ouQjut performance, requires frequent water supply, and is difficult to seal, and therefore the production amount thereof has decreased. 

The situation is different for sealed nickel/cadmium batteries, due to the internal oxygen cycle. Figure 1.15 illustrates the heat evolution of a sealed nickel/ cadmium battery during constant-current charging with a charge factor of 1.4 (such an amount of overcharge is usual for conventional charging methods but can only be applied to comparably small batteries < 10 Ah). 

Figure 1.15 Charging of a sealed nickel/cadmium battery with constant current 0.2 C(A). During 7 hours 140% of the nominal capacity are recharged, which corresponds with a charge factor 1.4. For comparison, all values are converted to 100 Ah of nominal capacity. Actually, batteries of this type and for such a charging schedule are only available in sizes < 10 Ah.

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... 

Various types of plastic materials are used in the different systems. In lead-acid batteries it is a must to use glass, rubber, or plastics on account of the high cell voltage that would destroy all metals. The advantage of a plastic container is that no insulation is required between adjacent cells. A general drawback of plastic materials is their permeability for gasses, water vapor, and volatile substances. Therefore, with sealed nickel/cadmium batteries and also nickel/metal hydride batteries metal is used as container material. 

In sealed nickel/cadmium batteries, oxygen evolution and oxygen reduction that form the internal oxygen cycle are the only reactions during overcharging (cf. Section 1.8.2.2). 

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