Button batteries

All flashlight batteries, button batteries, compact rechargeable batteries and vehicle storage batteries operate under the same basic principles. An electrochemical cell is constructed of two chemicals with different electron-attracting capabilities. Called an electrochemical couple, these two chemicals, itntncrscd in an electrolyte (material that carries the flow of energy between electrodes), are connected to each other through an external circuit. 

A button battery is much smaller than an alkaline battery. Button batteries are commonly used in watches, as shown in Figure 11.9. Because of its small size, the button battery is also used for hearing aids, pacemakers, and some calculators and cameras. The development of smaller batteries has had an enormous impact on portable devices, as shown in Figure 11.10. 

From a preliminary screening of importation data from the governmental central statistics office, it was observed that mercury was imported as mercury quicksilver and mercury colloidal suspension. Imported goods that contained mercury were mercury vapour lamps, TV camera tubes, clinical thennometers, batteries (button cell), fluorescent lamps and electrical switches. Mercury could also be present in coal that is imported to be used for power generation and other consumer products (e.g. bleaching creams). 

Lithium/Manganese dioxide 3.0 500 800 Primary battery button and cylindric cell... 

FIGURE 6.11 Performance of AA- (or equivalent) size battery at various current drains at 20 . A Ni-Cd battery B Ni-MH battery C Li-Ion D zinc-alkaline battery E. Li/MnOj battary (2/3A size) F Zn/ak battery (button configuration). A-C are secondary batteries. D-F are... 

TABLE 7.4 Comparison of Primary Batteries (Button Configuration) ... 

FIGURE 11.2 Zinc/mercuric oxide battery—button configuration. Courtesy of Duracell, Inc.)... 

FIGURE 28.3 Nickel-cadmium battery, button configuration. 

Battery type Micro battery Traditional or micro battery Micro battery Button or micro battery... 

There are three main configurations of nickel-cadmium batteries — button cells, cylindrical cells and rectangular cells. These are discussed below. 

The titanium sulfide is able to act as a lithium reservoir. On iatercalation with lithium, the titanium lattice expands from ca 570 to 620 pm as the iatercalation proceeds to completion on formation of TiI iS2. Small button cells have been developed, incorporating lithium perchlorate ia propyleae carboaate electrolyte, for use ia watches and pocket calculators (see Batteries). 

As of this writing, there is Httle commercialization of advanced battery systems. Small rechargeable lithium button cells have been commercialized, however, by Sanyo, Matsushita (Panasonic), and Toshiba. These cells are intended for original equipment manufacturer (OEM) use in appHcations such as memory backup and are not available to the general consumer. 

The button cells that provide the energy for watches, electronic calculators, hearing aids, and pacemakers are commonly alkaline systems of the silver oxide-zinc or mercuric oxide-zinc variety. These alkaline systems provide a vei y high energy density, approximately four times greater than that of the alkaline zinc-manganese dioxide battery. 

A starter or contactor with manual push-button or thermostatic operation to start and stop the fan normally controls simple systems. More complex systems that incorporate components that need control or monitoring are normally operated from purpose-built central control panels. The most common functions provided are fan motor stop, start and speed control, damper control, filter-condition indication and heater battery control. For optimum control, the system should be automatically controlled from thermostats or other sensors and a timeswitch. 

The capacity of single-use alkaline zinc-air cells is twice that of manganese dioxide-zinc cells. They cost less than silver oxide-Zn batteries or Li batteries. The best example of consumer usage is the hearing-aid button cell. In sealed condition it can be... 

It is so universally applied that it may be found in combination with metal oxide cathodes (e.g., HgO, AgO, NiOOH, Mn02), with catalytically active oxygen electrodes, and with inert cathodes using aqueous halide or ferricyanide solutions as active materials ("zinc-flow" or "redox" batteries). The cell (battery) sizes vary from small button cells for hearing aids or watches up to kilowatt-hour modules for electric vehicles (electrotraction). Primary and storage batteries exist in all categories except that of flow-batteries, where only storage types are found. Acidic, neutral, and alkaline electrolytes are used as well. The (simplified) half-cell reaction for the zinc electrode is the same in all electrolytes ... 

Zinc-silver oxide batteries as primary cells are known both as button cells, e.g., for hearing aids, watches, or cameras, and for military applications, usually as reserve batteries. Since the latter after activation have only a very short life (a few seconds to some minutes), a separation by cellulo-sic paper is generally sufficient. 

The first use of lithium alloys as negative electrodes in commercial batteries to operate at ambient temperatures was the employment of Wood s metal alloys in lithium-conducting button-type cells by Matsushita in Japan. Development work on the use of these alloys started in 1983 [10], and they became commercially available somewhat later. 

This section reviews the state-of-the-art in battery separator technology for lithium-ion cells, with a focus on separators for spirally wound batteries in particular, button cells are not considered. 

A battery is a galvanic cell that generates electrical current to power a practical device. Batteries can be as small as the buttons that power cameras and hearing aids or large charge storage banks like those of electric automobiles. 

An increasing number of household batteries are being used today. On average, a person owns about two button batteries, 10 normal (A, AA, AAA, C, D, 9V, etc.) batteries, and throws out about eight household batteries per year. About 3 billion batteries are sold annually in the United States averaging about 32 per family or 10 per person.5 9 Table 29.1 indicates the typical types of household batteries. 

There are two major types of household batteries (a) Primary batteries are those that cannot be reused. They include alkaline/manganese, carbon-zinc, mercuric oxide, zinc-air, silver oxide, and other types of button batteries, (b) Secondary batteries are those that can be reused secondary batteries (rechargeable) include lead-acid, nickel-cadmium, and potentially nickel-hydrogen. 

Mercuric oxide batteries are being gradually replaced by new technologies such as silver oxide and zinc-air button batteries that contain less mercury. 

Mercury oxide and silver oxide button batteries are sometimes collected by jewelers, pharmacies, hospitals, and electronic or hearing aid stores for shipping them to companies that reclaim mercury or silver. Some batteries cannot be recycled. If recycling is not possible, batteries should be saved for disposing of at a hazardous waste collection. Battery recycling and button battery collection may be good options at present, but may change as the mercury concentration in the majority of button batteries continues to decrease. 

These types of batteries are available in button and prismatic forms. Their main application is as power sources for hearing aids. Other applications include various specialty uses in the notebook computers, electronic pagers, portable battery chargers, various medical devices, the wireless crew communicator systems [18, 19]. 

Button cells consist of cathode and anode cans (used as the terminals), powdered zinc anode, containing gelled electrolyte and the corrosion inhibitor, separator with electrolyte, thin (0.5 mm) carbon cathode with catalyst and PTFE, waterproof gas-permeable (teflon) layer and air distribution layer for the even air assess over the cathode surface. Parameters of battery depend on the air transfer rate, which is determined by quantity and diameters of air access holes or porosity of the gas-diffusion membrane. Air-zinc batteries at low rate (J=0,002-0,01C at the idle drain and J= 0,02-0,04C at the peak continuous current) have flat discharge curves (typical curve is shown by Figure 1). 

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