Battery mercury (also called mercuric oxide battery , or mercury cell ) is a non-rechargeable electrochemical battery, the main cell. Mercury batteries use the reaction between mercury oxide and zinc electrodes in alkali electrolytes. The voltage during discharge remains practically constant at 1.35 volts, and its capacity is much larger than the same size zinc carbon batteries. The mercury batteries are used in the form of button cells for watches, hearing aids, cameras and calculators, and in larger forms for other applications.
For a time during and after World War II, batteries made with mercury became a popular source of electricity for portable electronic devices. Due to the toxic mercury content and environmental concerns about its disposal, the sale of mercury batteries is now banned in many countries. Both ANSI and IEC have revoked their standards for mercury batteries.
Video Mercury battery
Baterai Video Mercury
Maps Mercury battery
History
The zinc-oxide mercury battery system was known more than 100 years ago but was not widely used until 1942, when Samuel Ruben developed a balanced mercury cell useful for military applications such as metal detectors, ammunition, and walkie-talkies. The battery system has a long shelf life (up to 10 years) and stable voltage output. After the Second World War, the battery system was widely applied to small electronic devices such as pacemakers and hearing aids. The mercury oxide batteries are manufactured in various sizes from mini button cells used for hearing aids and electric watches, cylinder types used for portable electronic equipment, rectangular batteries used for transistor radios, and large multisell packs used for industrial applications such as radio remote control for crane overhead system. In the United States, mercury oxide batteries are manufactured by companies including P. R. Mallory and Co Inc, (now Duracell), Union Carbide Corporation (formerly called battery divisions now called Energizer Holdings), RCA Corporation, and Burgess Battery Company.
battery Map Mercury
Chemistry
Mercury batteries use pure mercury (II) oxide (HgO) - also called mercury oxide - or a mixture of HgO with manganese dioxide (MnO 2 ) as the cathode. Mercuric oxide is a non-conductor, so some graphite mixes with it; graphite also helps prevent the collection of mercury into large droplets. The half-reactions on the cathode are:
- HgO H 2 O 2e - -> Hg 2OH -
with a standard potential of 0.0977 V vs NHE.
The anode is made of zinc (Zn) and is separated from the cathode by a layer of paper or other porous material immersed in an electrolyte; this is known as the salt bridge. Two half reactions occur on the anode. The first consists of an electrochemical reaction step:
- Zn 4OH - -> Zn (OH) 4 -2 2e -
followed by a chemical reaction step:
- Zn (OH) 4 -2 -> ZnO 2OH - H 2 O
resulting in an overall half-anode reaction of:
- Zn 2OH - -> ZnO H 2 O 2e -
The overall reaction for the battery is:
- Zn HgO -> ZnO Hg
In other words, during discharge, zinc oxidized (loss of electrons) into zinc oxide (ZnO) while the mercury oxide becomes reduced (electron gain) to form mercury elements. Extra little mercury oxygen is introduced into cells to prevent the evolution of hydrogen gas at the end of life.
Electrolytes
Sodium hydroxide or potassium hydroxide is used as an electrolyte. Sodium hydroxide cells have an almost constant voltage at low discharge currents, making them ideal for hearing aids, calculators, and electronic watches. The potassium hydroxide cell, in turn, provides a constant voltage at higher currents, making it suitable for applications requiring current surges, such as photographic cameras with flash, and backlit clocks. Potassium hydroxide cells also perform better at lower temperatures. The mercury cells have a very long shelf life, up to 10 years.
Mercuric oxide and cadmium
Different mercury batteries use mercuric oxide and cadmium. It has a much lower terminal voltage of about 0.9 volts and has a lower energy density, but has an extended temperature range, in a special design of up to 180 C. Because cadmium has a low solubility in alkali electrolytes, this battery has a storage life which is old. This 12 volt type battery was previously used for residential smoke detectors. It is designed as a series of cell stacks, where one cell has a reduced capacity. During discharge, the battery terminal voltage will drop significantly when the smaller cell is discarded, providing a two-step voltage characteristic to warn of the need for replacement.
Electrical characteristics
Mercury batteries using the mercury oxide cathode (II) have a very flat discharge curve, withstand a voltage of 1.35 V (open circuit) up to about 5% of their lifetime, when their voltage drops rapidly. Voltages remain within 1% for several years on light loads, and over a wide temperature range, making mercury batteries useful as voltage references in electronic instruments and in photographic light meters.
Battery mercury with cathode made from a mixture of mercury oxide and manganese dioxide has an output voltage of 1.4 V and a more oblique discharge curve.
Product ban
The European Commission Directive 1991 91/157, when adopted by member states, prohibits the marketing of certain types of batteries containing more than 25 milligrams of mercury, or, in the case of alkaline batteries, more than 0.025% by weight of mercury. In 1998 the prohibition was extended to cells containing more than 0.005% by weight of mercury.
In the United States, in 1992, the state of New Jersey banned the sale of mercury batteries. In 1996, the United States Congress passed a Mercury and Refillable Battery Management Act that prohibits the further sale of mercury-containing batteries unless manufacturers provide reclamation facilities, effectively banning their sales. The silver oxide battery - Wikipedia Wikipedia the free encyclopedia imgstorage.ga/wp-contents/uploads/2018/06/78pu8h.jpg "style =" max-width: 100%; height: auto; "title =" Silver oxide battery - Wikipedia English Wikipedia, the free encyclopedia ">
Substitute
The prohibition of mercury oxide battery sales causes many problems for photographers, whose equipment often relies on favorable disposable and long-life debit curves. The alternatives used are zinc-air batteries, with the same discharge curve, high capacity, but shorter life (few months), and poor performance in dry climates; alkaline batteries with voltages that vary widely throughout their lifetime; and higher-voltage silver-oxide batteries (1.55 V) and very flat discharge curves, making them perhaps the best, though expensive, replacement after re-calibrating the meter to a new voltage.
Special adapters with voltage dropping Schottky or germanium diodes allow silver oxide batteries to be used in equipment designed for mercury batteries. Since the voltage drop is a non-linear function of the current flow, the diode does not yield a highly accurate solution for applications where current flow varies significantly. The current drawn by the old CdS light meter is usually in the range of 10 Ã,ÂμA to 200 ÂμA (eg the Minolta SR-T equipment series). Different types of active voltage setting circuits using SMD transistors or integrated circuits have been designed, however, they are often difficult to integrate into a narrow battery compartment space. The replacement should operate at low voltage generated by a single cell, and the lack of a power switch on many traditional light meters makes the ultra-low power design necessary.
Use in zinc battery
Previously, dry cell zinc anodes were merged with mercury, to prevent zinc side reactions with electrolytes that would reduce battery life. Mercury does not take part in chemical reactions to the battery. Manufacturing has turned into a more pure level of zinc, so amalgamation is no longer necessary and mercury is removed from dry cells.
See also
- List of battery types
- List of battery sizes
- Battery type comparison
- Battery recycling
- Battery Nomenclature
References
External links
Article source: Wikipedia
Source of the article : Wikipedia
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