Nickel-cadmium cells applications

Lower cost and lower weight cylindrical cells have been made using plastic bound or pasted actwe material pressed into a metal screen. Tliese cells suffer slightly in utilization at high rates compared to a sintered-plate cylindrical cell, but they may be adequate for most applications. Tlie effect of temperature and discharge rate on the capacity of sealed nickel-cadmium cells is illustrated in Figure 8 and Table 3. 

The manufacture of secondary batteries based on aqueous electrolytes forms a major part of the world electrochemical industry. Of this sector, the lead-acid system (and in particular SLI power sources), as described in the last chapter, is by far the most important component, but secondary alkaline cells form a significant and distinct commercial market. They are more expensive, but are particularly suited for consumer products which have relatively low capacity requirements. They are also used where good low temperature characteristics, robustness and low maintenance are important, such as in aircraft applications. Until recently the secondary alkaline industry has been dominated by the cadmium-nickel oxide ( nickel-cadmium ) cell, but two new systems are making major inroads, and may eventually displace the cadmium-nickel oxide cell - at least in the sealed cell market. These are the so-called nickel-metal hydride cell and the rechargeable zinc-manganese dioxide cell. There are also a group of important but more specialized alkaline cell systems which are in use or are under further development for traction, submarine and other applications. 

The annual production value of small, sealed nickel-cadmium cells is over 1.2 I09. However, environmental considerations relating to cadmium are necessitating changes in the fabrication techniques, as well as recovery of failed cells. Batteiy system designers are switching to nickel-metal hydride (MH) cells for some applications, typically in AA -size cells, to increase capacity in the same volume and avoid the use of cadmium. 

Developed in the 1960s, it makes use of different technologies for its electrodes NiO(OH) is from nickel cadmium and H2 from fuel-cell systems. Because of its longer cycle life the main use of the nickel-hydrogen battery is in aerospace applications to replace the nickel cadmium cells. For example, the Hubble Space Telescope launched in 1990 was equipped with nickel-hydrogen cells [12]. 

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

But the problem can be solved, as has been shown by the development groups of rechargeable lithium-ion batteries. Nickel/metal hydride cells (having 50% more capacity and no cadmium content) had just started to penetrate the market to the debit of nickel/cadmium cells, and are being pushed away now by rechargeable lithium-ion batteries. Main applications are cellular phones, mobile phones, and video cameras. It cannot yet be foreseen whether nickel/cadmium will disappear from the market, because they cannot be substituted for in the use in tools. Never in the past has a new battery system eliminated an established system totally. 

Calcium-lead alloy batteries, because of the gelled electrolyte, are insensitive lo orientation, as are scaled nickel-cadmium cells. They can therefore be stored, charged or discharged in any position, even upside-down. This characteristic has obvious advantages in cyclic or float applications such... 

The nickel-metal hydride couple lends itself to a wound eonstruetion similar to that used by present-day wound niekel-eadmium cells. The basie components consist of the positive and negative eleetrodes insulated by plastic separators similar to those used in nickel-cadmium products. The sandwiched electrodes are wound together and inserted into a metallic can which is sealed after injection of a small amount of potassium hydroxide electrolyte solution. Tne result is a cell which bears a striking resemblance to current sealed nickel-cadmium cells. The nickel-metal hydride chemistry is also applicable to prismatic cell designs which evoke greater interest as product profiles become thinner. 

Figure 31.20 Sample capacity versus temperature curve for Eveready OB90 and OB90T sealed nickel-cadmium cells, 1.2 V. 20Ah capacity. Ranges of temperature applicable to operation are cha e, 0-45 C discharge, -20 to 45 C storage, -40 to 60°C. Dischargecurrent 9 mA (Courtesy of Union Carbide)...

Comparison of lithium-iodine and nickel-cadmium cells in CMOS-RAM applications 38/6... 

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