Nickel-cadmium cell manufacturers

A number of manufacturers started commercial production of nickel—MH cells in 1991 (31—35). The initial products are "AA"-size, "Sub-C", and "C -size cells constmcted in a fashion similar to small sealed nickel —cadmium cells. Table 6 compares the Ovonics experimental cell and a similar sized nickel—cadmium cell. Ovonics also deUvered experimental electric vehicle cells, 22 A-h size, for testing. The charge—discharge of "AA" cells produced in Japan (Matsushita) are compared in Figure 22. 

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. 

Individual countries within the European Community handle the battery waste problem differently. For example, in Switzerland all used consumer batteries are considered hazardous waste and must be collected separately from ordinary household waste. Batteries must be recycled or stored in warehouses, not landfilled. A tax is collected on all new battery purchases to help defray the cost of recycling. In Italy, spent dry batteries are considered as hazardous waste and must be collected separately. In Sweden (10), the environmental issues relatii to waste batteries are addressed in the Control of Chemicals Bill and in the Decree on Environmentally Hazardous Batteries. All used batteries containing cadmium or mercury are collected separately under government control. The cadmium is then recycled. Regulations are in place for the manufacture of nickel/cadmium cells, limiting the exposure of workers and the emission of toxic materials. 

A variety of plate formulations are used in vented, sintered nickel-cadmium cells produced by different manufacturers. The plates differ according to the nature of the substrate, method of sintering, impregnation process, formation and termination techniques. The predominate plate fabrication process used for vented sintered plate over the years has been described by Heischer." There are several reviews on electrode fabrication processes that have been used in flooded vented cells. ... 

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. 

Most silver-cadmium cells contain cadmium electrodes that are manufactured by pressed-power or pasting techniques. Although other methods have been used, such as impregnating nickel plaque with cadrnium salts, as is done for nickel-cadmium cells, the most common method in silver-cadmium cells is to press or paste a mixture of cadmium oxide or cadmium hydroxide with a binder onto a silver or nickel grid. These processes are similar to those used for the pressed and pasted zinc electrodes. 

SAFT manufacture various types of charger for use with their sealed nickel-cadmium cells and batteries in... 

Sealed nickel-cadmium cells have a high effective capacitance. Their impedance is so low that cells being, in effect, continuously overcharged make excellent ripple filters. Cell impedance is dependent on frequency and state of charge of the cell. It is lower for a charged cell than it is for a discharged cell. Values of impedance and resistance of Eveready cells are shown on the individual specification sheets for each cell (available from the manufacturer). 

Subcategory A encompasses the manufacture of all batteries in which cadmium is the reactive anode material. Cadmium anode batteries currently manufactured are based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples (Table 32.1). The manufacture of cadmium anode batteries uses various raw materials, which comprises cadmium or cadmium salts (mainly nitrates and oxides) to produce cell cathodes nickel powder and either nickel or nickel-plated steel screen to make the electrode support structures nylon and polypropylene, for use in manufacturing the cell separators and either sodium or potassium hydroxide, for use as process chemicals and as the cell electrolyte. Cobalt salts may be added to some electrodes. Batteries of this subcategory are predominantly rechargeable and find application in calculators, cell phones, laptops, and other portable electronic devices, in addition to a variety of industrial applications.1-4 A typical example is the nickel-cadmium battery described below. 

Cadmium (Cd) anode cells are at present manufactured based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples. Thus wastewater streams from cadmium-based battery industries carry toxic metals cadmium, nickel, silver, and mercury, of which Cd is regarded the most hazardous. It is estimated that globally, manufacturing activities add about 3-10 times more Cd to the atmosphere than from natural resources such as forest fire and volcanic emissions. As a matter of fact, some studies have shown that NiCd batteries contribute almost 80% of cadmium to the environment,4,23 while the atmosphere is contaminated when cadmium is smelted and released as vapor into the atmosphere4 Consequently, terrestrial, aquatic, and atmospheric environments become contaminated with cadmium and remain reservoirs for human cadmium poisoning. 

Cadmium, along with nickel, forms a nickel-cadmium alloy used to manufacture nicad batteries that are shaped the same as regular small dry-cell batteries. However, a major difference is that the nicads can be recharged numerous times whereas the common dry cells cannot. A minor difference between the two types of cells is that nicads produce 1.4 volts, and regular carbon-zinc-manganese dioxide dry-cell batteries produce 1.5 volts. 

Nickel(lll) oxide, prepared from a nickel(ii) salt and sodium hypochlorite, is used for the oxidation of alkanols in aqueous alkali [46]. Residual nickel(Ii) oxide can be re-activated by reaction with sodium hypochlorite. Nickel oxides have also long been used in the manufacture of the positive pole in the Edison nickel-iron rechargeable battery, now largely superseded by die lead-acid accumulator, and in the Jungner nickel-cadmium batteries used as button cells for calculators [47]. Here, prepared nickel oxide is pressed into a holding plate of perforated nickel. Such prepared plates of nickel(lli) oxide have been proposed as reagent for the oxidation, in alkaline solution, of secondary alcohols to ketones and primary alcohols to carboxylic acids [48]. Used plates can be regenerated by anodic oxidation. 

RAM cells are manufactured and shipped charged and have an initial capacity of about 1.8 Ah for AA-sized cells discharged at 50 mA (in comparison with, say, 2 Ah for an equivalent primary cell). This capacity falls to 1 Ah after storage for 3 years at room temperature. At higher drains, the initial capacity drops to about 0.6 Ah at 400 mA (Fig. 6.14). Cells are designed to operate within a temperature range of 0-65°C. The higher internal resistance of RAM cells limits their maximum continuous output current and also their peak output currents in comparison both with primary cells and with nickel-cadmium and nickel-metal hydride secondary cells. A new cell will have an internal resistance of approximately 0.1 2, but this will rise to 0.25 2 with use. 

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. 

Its current capacity is 1,400 tormes with 6 distillation furnaces. It specialises in the treatment of used nickel cadmium sealed cells and those rejected during manufacture. 

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