car accumulator. Called
battery, electric battery or just battery, the device that stores electrical energy using electrochemical methods and then returns almost entirely, this cycle can be repeated by a number of times. This is a secondary electric generator, ie a generator can not operate without electricity previously supplied him with what is called charging.
also often called battery as many times several of them are connected in series to increase the supply voltage. Thus, a car battery is made internally by 6 elements accumulator lead-acid type, each of which supplies electricity at a voltage of about 2 V, so that all the usual 12 V supply, or 12 items at 24 V for trucks.
The term battery in Castilian, called the non-rechargeable power generators. Both battery and battery are terms from the early days of electricity, in which several cells or cells - in the first case, one above another, "stacked", and the second, attached laterally, "on battery" , as is done today in order to increase the magnitude of electrical phenomena and to study them systematically. This explanation suggests that either serve to any names, but the custom has fixed the distinction. Contents
Operating Principles of Operation battery is based essentially on some sort of reversible process, ie a process whose components are not consumed or lost result, but merely transformed into another, which in turn can return to the state first in the right circumstances. These circumstances are, in the case of batteries, the closure of the external circuit during the discharge process and the implementation of a stream, just outside during the load.
turns out that such processes are quite common, oddly enough, in the relations between the chemicals and electricity during the process called electrolysis , and voltage generators or batteries . The nineteenth century researchers devoted many efforts to observe and investigate this phenomenon, which was named polarization.
An accumulator is thus a device that takes the polarization achievable limits, and generally consists of two electrodes the same or different material, immersed in an electrolyte . History
Alessandro Volta announced his invention of the stack to the Royal London Society, March 20 of 1800. Johann Wilhelm Ritter
built his electric battery 1803. Like many other that followed, was a theoretical and experimental prototype, with no possible practical application.
In 1860 , Gaston Plante developed the first model of lead-acid battery with pretensions to be a usable device, which was only very relatively, so it was not successful. In the late nineteenth century, however, the electricity was rapidly becoming everyday items, and when I planted again to publicly explain the features of your store, in 1879 , had a better reception, so it began to be manufactured and used almost immediately, beginning an intense and ongoing process of development to perfect it and ignore its deficiencies, a process that continues today.
Thomas Alva Edison invented in 1900 , another type of battery with electrodes of iron and nickel, whose electrolyte is potassium hydroxide (KOH). First commercialized in 1908 , and are the basis of current models alkaline rechargeable or not.
Also by 1900, in Sweden, Berg invented Junger and Ni-Cd battery, which uses cadmium anodes instead of iron, being very similar to that of ferronickel in other characteristics.
battery types
As their size and other characteristics external concerns, consult this list , since many of them are common to batteries and accumulators and are standardized.
As far as concerns their internal nature, are commonly found in trade accumulators of the following types:
lead accumulator is composed of two electrodes lead, so that when the device is downloaded , is in the form of lead sulfate (PbSO4 II) embedded in a matrix of metallic lead (Pb), the electrolyte is a solution of sulfuric acid . This type of battery is still used even in many applications, including in the car. Its operation is as follows:
During the initial charging, lead sulfate (II) is reduced to lead metal at the negative pole, while the anode forms lead oxide (IV) (Pb O2) . Therefore, it is a dismutation process . No hydrogen is released, since the reduction of protons to elemental hydrogen is kinetically hindered at a lead surface, a favorable characteristic is reinforced by including the small amounts of silver electrodes. Hydrogen evolution would cause slow degradation of the electrode, helping it crumble mechanically parts of it, irreversible changes that shorten the battery service life.
During discharge processes are reversed loading. Lead oxide (IV) is reduced to lead sulfate (II), while the elemental lead is oxidized to sulfate also give lead (II). Exploit the electrons exchanged in the form of electrical current through an external circuit. It is, therefore, of a switch. The term commences elementary processes are:
PbO2 + 2 H2SO4 + 2 e--> 2 H2O + SO42-
PbSO4 + Pb + SO42--> PbSO4 + 2 e-
low discharge in the concentration of sulfuric acid because it creates lead sulphate and increases the amount of water released in the reaction. As concentrated sulfuric acid has a density greater than the dilute sulfuric acid, the acid density can be an indicator for charging status of the device.
However, this process can be repeated indefinitely, because when the lead sulfate crystals form very large, and not respond well to the processes outlined, so you lose the essential characteristic of reversibility. We then say that the battery is sulfated and must be replaced by a new one.
The batteries of this type sold today use a paste electrolyte, which does not evaporate and does a lot more comfortable and safer to use.
Alkaline Battery
ferronickel also called, the electrodes are shaped steel plates with honeycomb mesh inserts nickel oxide (NiO), which form the positive electrode, and ferrous oxide (FeO), the negative, being formed the electrolyte solution of potassium hydroxide (KOH). During the load is an anodic oxidation process and a cathodic reduction , becoming the nickel oxide in nickel and ferrous oxide in metallic iron. This reaction occurs in reverse during unloading.
In 1866, George Leclanché invented in France the "stack dry "(Zinc-Manganese Dioxide) system that still dominates the world market for primary batteries. Alkaline batteries (for "high power" or "long life") are similar to those of Leclanché, but instead of ammonium chloride, lead chloride, sodium or potassium. They last longer because zinc is not exposed to an acidic environment such as ammonium ions that cause the conventional battery. As the ions move more easily through the electrolyte, produces more power and a more stable flow.
The higher cost stems from the difficulty of sealing the cell against leakage of hydroxide. Almost all are shielded, which prevents the shedding of constituents. However, this shield does not have unlimited time. Alkaline dry cells are similar to common dry cells, with the following exceptions:
the electrolyte is basic (alkaline), because it contains KOH
the inner surface of the container of Zn is rough, this provides a larger contact area.
Alkaline batteries have a longer shelf life than the common dry cells to better withstand constant use.
voltage alkaline battery is close to 1.5 v. During unloading, the reactions in the alkaline dry cell are:
Anode: Zn (S) + 2 OH-(aq) Zn (OH) 2 (s) +2 e-
Cathode: 2 MnO2 (S) + 2 H2 O (l) + 2 e- 2MnO (OH) (s) + 2 OH-(ac)
Global: Zn (s) +2 MnO2 (s) 2H2O (l) Zn (OH) 2 (aq) + 2MnO (OH) (s)
The anode is made of a paste of zinc amalgamated with mercury (total 1%), carbon or graphite.
devices are used for complex and energy intensive. In versions 1.5 volt, 6 volt and 12 volts are used, for example, remote controls (remote control) and alarms.
alkaline manganese batteries with mercury content of around 0.1% of its total weight is an enhanced version of the previous stack, which has replaced the chloride ion conductor ammonium hydroxide Potassium (hence the name of alkaline). The battery container is steel, and disposition of zinc and manganese oxide (IV) is the opposite, placing the zinc powder now in the middle. The amount of mercury used to regulate the discharge is higher. This gives more time, more constancy in time and better performance. By contrast, the price is higher. It also provides an electromotive force of 1.5 V. It is used in most consumer devices such as portable recorders, motorized toys, electronic flashes.
The amalgamated zinc anode is the cathode material is a polarizer that is based on manganese dioxide, mercuric oxide intimately mixed with graphite, and in rare cases Ag2O silver oxide (the latter two are of use expensive, hazardous and toxic), to reduce its electrical resistivity. The electrolyte is a solution of potassium hydroxide (KOH), which presents a very low internal resistance, allowing not to take internal discharges and energy can be stored for a long time. This electrolyte in the battery business is hardened gelatin or cellulose derivatives.
This type of battery is manufactured in two ways. In one, the anode consists of a corrugated zinc strip, spirally wound from 0.051 to 0.13 mm in thickness, which is Amalgam after assembly. Two strips absorbent paper interdevanadas alkali resistant paper strip with zinc, zinc so that it extends to the top and bottom paper. The anode is insulated from the metal box with a polystyrene sleeve. The top of the stack is made of copper and makes contact with the strip of zinc to form the negative terminal of the battery. The battery is sealed with a grommet or eyelet made of neoprene. The battery casing is chemically inert to the ingredients and form the positive electrode.
Alkaline Zinc 14% (anode) Toys, tape players, cameras, recorders
22% manganese dioxide (cathode)
Coal: 2%
Mercury 0.5 to 1% (anode)
potassium hydroxide (electrolyte)
42% plastic and sheet
contains an alkaline compound called potassium hydroxide. Its duration is six times greater than that of zinc-carbon. It is composed of manganese dioxide, potassium hydroxide, zinc paste amalgamated with Mercury (total 1%), carbon or graphite. According to the European Directive of March 18, 1991, these batteries can not exceed the amount of 0.025% mercury.
This type of battery has some cons:
An alkaline battery can contaminate 175,000 liters of water, which becomes the average water consumption of all the lives of six people.
An ordinary battery, also called zinc-carbon, can contaminate 3,000 liters of water.
nasal septum perforations.
Zinc, Manganese, Bismuth, Copper and Silver: These are toxic substances that produce various alterations in human health. Zinc, Manganese and Copper are essential for life, in minute amounts, toxic in high doses. Bismuth and Silver are not essential for life.
Nickel Hydride Batteries (Ni-H)
utilize a hydroxide anode and cathode nickel alloy metal-hydride batteries. Each cell of Ni-H can provide a voltage of 1.2 V and a capacity between 0.8 and 2.3 Ah. Its energy density reaches 80 Wh / kg. These batteries are affected by the so-called memory effect, which is limited in each charging voltage or the capacity (because of a long, high temperature or high current), precluding the use of all its energy.
Nickel-Cadmium Batteries (Ni-Cd)
They use a nickel hydroxide anode and cathode of a compound of cadmium . The electrolyte is potassium hydroxide . This configuration of materials can recharge the battery once it is exhausted, for reuse. Each NiCd cell can provide a voltage of 1.2 V and a capacity between 0.5 and 2.3 Ah. No However, its energy density is only 50 Wh / kg, which means they have to be recharged every so often. They are also affected by memory effect.
Lithium-Ion Battery (Li-ion) batteries
The Lithium-Ion (Li-ion) use a lithium anode and a cathode Ion. Its development is more recent, and can reach densities of around 115 Wh / kg. Also, do not suffer from memory effect .
Lithium Polymer Batteries (Li-Poly)
are a variation of Lithium-Ion Battery (Li-ion) . Its characteristics are very similar, but allow higher energy density and a significantly higher discharge rate.
Fuel Cells
The fuel cell is not an accumulator itself, although it converts chemical energy into electricity and is rechargeable. Works with hydrogen . (Other fuels such as methane or Methanol are processed prior to hydrogen).
high capacity condenser
Although high-capacity capacitors electrochemical batteries are not strictly speaking, are now getting enough capacity large (several farads, F) so that they can be used as a battery when the power supplied are small.
parameters of a battery voltage
The or potential (in volts ) is the first parameter to consider, as is what usually determines whether the accumulator should use to which it is intended. Is fixed by the reduction potential of redox couple used, generally between 1 V and 4 V per cell.
The current that can supply the item, as ampere (A), is the second factor. Is particularly important in some cases the maximum current obtainable; p. eg., starter motors for cars require brutal efforts of the battery when put into operation (tens of A), so you must act for a short time.
electrical capacity is measured in practice by reference to the time of loading and discharge in Ah. SI unit is the coulomb (C).
1 Ah = 1000 mAh = 3600 C, 1 C = 1 Ah/3600 = 0.278 mAh.
Note, however, that, when you get indications on the body of batteries or packs, as Please charge at C/10 for 12 hours the letter C does not refer to Coulomb, but maximum load may receive the battery, so that in the previous case, if they were battery capacity 1200 mAh, you should apply a charging current = 120 mA during 1200-1210 the number of hours indicated.
The stored energy is usually measured in Wh ( watt-hour), the SI unit is the joule (unit) .
1 Wh = 3600 J = 3.6 kJ 1 J = 0.278 mWh
The resistance of the batteries is much lower than that of the batteries, allowing them to supply loads more intense than the latter, especially as transient. For example, the internal resistance of a lead-acid battery is of 0.006 ohm , and other Ni-Cd, from 0.009 ohm.
Finally, another important feature of a battery is its mass, ie, weighing, and the relationship between it and the electrical capacity (Ah / kg) or energy (Wh / kg) that can restore. In some cases it may also occupy a significant volume (m3 or liters).
The yield is the percentage ratio between the power received in the process of loading and delivery to the battery during discharge. The lead-acid battery is rated at over 90%.
batteries as contaminants
As seen, the batteries contain heavy metals and chemicals, many of them harmful environment. It is very important not to throw them away (in most countries this is not allowed) and take them to a recycling center. Currently, most vendors and specialty shops are also in charge of the batteries.
In Mexico, the release of mercury in batteries has occurred as a result of using three types of batteries: the oxide of mercury, the C-Zn and alkaline. In the first type, the metal content is 33% and were used in presentation and in other button sizes, from 1955. Theoretically, it ceased production in 1995, although there are sources that indicate that this process continues in Asia and distributed in the international market. For the second and third types of batteries, it is known that for several decades before 1990, they added mercury (0.5 to 1.2%) for best performance, with the highest alkaline content, also containing coal is sometimes contaminated with this metal naturally. In 1999, the INE requested an analysis of samples from three different brands of AA batteries normally consumed in Mexico, of which two were of Asian origin (of C-Zn) and alkaline European origin. The results were as follows: for those of Asian origin, the values \u200b\u200bwere between 0.18 mg / kg and 6.42 mg / kg, in terms of European origin the result was 0.66 mg / kg, and these amounts, equivalent to parts per million, does not exceed the limits of 0.025% under the Protocol on heavy metals taken in 1998 in Aarhus, Denmark, by members of the Economic Commission for Europe (UNECE). The previous sample was an isolated incident and it would be in the future to further analyze the mercury content in the largest possible number of brands. According to calculations presented in Table 10, an estimated 1,232 tons have been released over the past 43 years. In Mexico, the other sources of mercury are industry chlorine / soda, which is used in the process, and also products such as thermometers, various types of switches and fluorescent lamps. According to official information and is not removed mercury in Mexico, although data on imports amounting to 130 tonnes in the last three years. Mercury is a local and global pollutant par excellence. Environmental chemistry for this toxic metal is very complex, given its properties, it evaporates at room temperature, the atoms travel far, to be deposited in bodies of water are transformed into organic mercury (methyl mercury) for aerobic and anaerobic mechanisms , this is how it becomes contaminated, among others, seafood. Another form of mercury poisoning is inhalation of vapors from the mercury in its metallic form indoors. Methyl mercury can cross the placenta, accumulate and cause damage to the brain and tissues of infants who are particularly sensitive to this substance. There may also be exposed to mercury through breast milk, in this case, the effects can cause developmental problems, delays in walking, speech or mental lack of coordination, blindness and seizures. In adults, chronic exposure through ingestion of contaminated food, usually fish, can cause personality changes, loss of vision, memory or coordination, deafness, or problems in the kidneys and lungs. The International Agency for Research on Cancer (IARC, for its acronym in English) of the World Health Organization (WHO) considers to methyl mercury and its compounds as possibly carcinogenic to humans (Group 2B). Methyl mercury, which is the most toxic, accumulates in fish tissue, the larger specimens and older tend to concentrate higher levels of mercury.
Manganese: As the most used battery types are alkaline and C-Zn (approximately 76% of total batteries), the oxide manganese content in them is the pollutant that increased volume has been released into the environment over the past four decades, which is about 145.917 tons (Table 10). Regarding adverse effects on human health caused by this substance, several studies suggest serious neurological effects from oral exposure to manganese. For example, a study by the WHO reports that in 1981 poisoning was reported in a community in Japan, due to near a water well were buried around 400 pieces of batteries at a distance of approximately two meters, causing 16 cases of poisoning, three were fatal (including suicide). Manganese levels detected in water from that well was 14 milligrams per liter, while in other two wells reached levels 8 and 11 milligrams per liter. Community subjects exhibited disorders of psychological and neurological related to intoxication.
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