An opto-electric nuclear battery is a device that converts nuclear energy into light, which it then uses to generate electrical energy. A beta-emitter such as technetium-99 or strontium-90 is suspended in a gas or liquid containing luminescent gas molecules of the excimer type, constituting a "dust plasma." This permits a nearly lossless emission of beta electrons from the emitting dust particles. The electrons then excite the gases whose excimer line is selected for the conversion of the radioactivity into a surrounding photovoltaic layer such that a lightweight, low-pressure, high-efficiency battery can be realised. These nuclides are low-cost radioactive waste from nuclear power reactors. The diameter of the dust particles is so small (a few micrometers) that the electrons from the beta decay leave the dust particles nearly without loss. The surrounding weakly ionized plasma consists of gases or gas mixtures (such as krypton, argon, and xenon) with excimer lines such that a considerable amount of the energy of the beta electrons is converted into this light. The surrounding walls contain photovoltaic layers with wide forbidden zones as e.g. diamond which convert the optical energy generated from the radiation into electrical energy.
Description
The battery would consist of an excimer of argon, xenon, or krypton (or a mixture of two or three of them) in a pressure vessel with an internal mirrored surface, finely-ground radioisotope, and an intermittent ultrasonic stirrer, illuminating a photocell with a bandgap tuned for the excimer.[1] When the beta active nuclides (e.g. krypton-85 or argon-39) are excited, their own electrons in the narrow excimer band at a minimum of thermal losses that this radiation is converted in a high band gap photovoltaic layer (e.g. in p-n diamond) very efficiently into electricity. The electric power per weight compared with existing radionuclide batteries can then be increased by a factor 10 to 50 and more. If the pressure-vessel is carbon fiber/epoxy the weight to power ratio is said to be comparable to an air-breathing engine with fuel tanks. The advantage of this design is that precision electrode assemblies are not needed, and most beta particles escape the finely-divided bulk material to contribute to the battery's net power.
Disadvantages
1. High price of the radionuclides.
2. High-pressure (up to 10 MPa (100 bar)) heavy containment vessel.
3. A failure of containment in this form of device would release high-pressure jets of finely divided radioisotopes, forming an effective Dirty Bomb.
The inherent risk of failure is likely to limit this device to space-based applications, where the finely divided radioisotope source is only removed from a safe transport medium, and placed in the high-pressure gas, after the device has left Earth orbit.
Wednesday, March 24, 2010
Nickel oxyhydroxide battery
Nickel oxyhydroxide battery (abb. NiOx) is a new type of primary (non-rechargeable) cell. Batteries of this chemistry are sold under the brand names Duracell Power Pix and Panasonic Oxyride. NiOx batteries excel in high-drain applications such as digital cameras, and in this role, they can provide up to twice the life of an alkaline battery. NiOx batteries can be used in low-drain applications, however the cell's lifespan will be similar to a premium alkaline battery for these uses. NiOx batteries produce a higher voltage (1.7V) than alkaline batteries (1.5V) which can cause problems in certain products, such as equipment with incandescent light bulbs (such as flashlights/torches), or devices without a voltage regulator.
Molten salt battery
Molten salt batteries are a class of primary cell and secondary cell high temperature electric battery that use molten salts as an electrolyte. They offer both a higher energy density through the proper selection of reactant pairs as well as a higher power density by means of a high conductivity molten salt electrolyte. They are used in services where high energy density and high power density are required. These features make rechargeable molten salt batteries a promising technology for powering electric vehicles. Operating temperatures of 400 °C (752 °F) to 700 °C (1,292 °F), however, bring problems of thermal management and safety, and place more stringent requirements on the rest of the battery components. Some newer designs, such as the ZEBRA battery, operate at a lower temperature range of 270 °C (518 °F) to 350 °C (662 °F).
Primary cells
Referred to as thermal batteries the electrolyte is solid and inactive at normal ambient temperatures. Thermally activated (“thermal”) batteries were conceived by the Germans during WW II and were used in the V-2 rockets. Dr. Georg Otto Erb is credited with developing the molten-salt battery that used the heat of the rocket to keep the salt liquid during its mission. The technology was brought back to the United States in 1946 and was immediately adapted to replace the troublesome liquid-based systems that had previously been used in artillery proximity fuzes. These batteries have been used for ordnance applications (e.g., proximity fuzes) since World War II and, subsequent to that, in nuclear weapons. They are the primary power source for many missiles such as the AIM-9 Sidewinder, MIM-104 Patriot, BGM-71 TOW, BGM-109 Tomahawk and others. In these batteries the electrolyte is immobilized when molten by a special grade of magnesium oxide that holds it in place by capillary action. This powdered mixture is pressed into pellets to form a separator between the anode and cathode of each cell in the battery stack. As long as the electrolyte (salt) is solid, the battery is inert and remains inactive. Each cell also contains a pyrotechnic heat source which is used to heat the cell to the typical operating temperature of 400 - 550C.
There are two types of design. One uses a fuze strip (containing barium chromate and powdered zirconium metal in a ceramic paper) along the edge of the heat pellets to initiate burning. The fuze strip is typically fired by an electrical igniter or squib by application of electric current through it. The second design uses a center hole in the middle of the battery stack into which the high-energy electrical igniter fires a mixture of hot gases and incandescent particles. The center-hole design allows much faster activation times (tens of milliseconds) vs. hundreds of milliseconds for the edge-strip design. Battery activation can also be accomplished by a percussion primer, similar to a shotgun shell. It is desired that the pyrotechnic source be gasless. The standard heat source typically consist of mixtures of iron powder and potassium perchlorate in weight ratios of typically 88/12, 86/14, and 84/16. The higher the potassium perchorate level, the higher the heat output (nominally 200, 259, and 297 calories/gram, respectively).
This property of unactivated storage has the double benefit of avoiding deterioration of the active materials during storage and at the same time it eliminates the loss of capacity due to self-discharge until the battery is called into use. They can thus be stored indefinitely (over 50 years) yet provide full power in an instant when it is required. Once activated, they provide a high burst of power for a short period (a few tens of seconds) to over 60 minutes or more, with power output ranging from a few watts to several kilowatts. The high power capability is due to the very high ionic conductivity of the molten salt, which is three orders of magnitude or more greater than that of sulfuric acid in a lead-acid car battery. Older thermal batteries used calcium or magnesium anodes, with cathodes of calcium chromate or vanadium or tungsten oxides, but lithium-alloy anodes replaced these in the 1980s, with lithium-silicon alloys being favored over the older lithium-aluminum alloys. The corresponding cathode for use with the lithium-alloy anodes is mainly iron disulfide (pyrite) with cobalt disulfide being used for high-power applications. The electrolyte is normally a eutectic mixture of lithium chloride and potassium chloride. More recently, other lower-melting, eutectic electrolytes based on lithium bromide, potassium bromide, and lithium chloride or lithium fluoride have also been used to provide longer operational lifetimes; they are also better conductors. The so-called "all-lithium" electrolyte based on lithium chloride, lithium bromide, and lithium fluoride (no potassium salts) is also used for high-power applications, because of its high ionic conductivity.
These batteries are used almost exclusively for military applications ie "one-shot" weapons such as guided missiles. However, the same technology was also studied by Argonne National Laboratories in the 1980s for possible use in electric vehicles, since the technology is rechargeable.
A radioisotope thermal generator, e.g. pellets of 90SrTiO4, can be used for long-term delivery of heat for the battery after activation, keeping it in molten state.[1]
Secondary cells
Since the mid-1960s much development work has been undertaken on rechargeable batteries using sodium (Na) for the negative electrodes. Sodium is attractive because of its high reduction potential of -2.71 volts, its low weight, its non-toxic nature, its relative abundance and ready availability and its low cost. In order to construct practical batteries, the sodium must be used in liquid form. Since the melting point of sodium is 98 °C (208 °F) this means that sodium based batteries must operate at high temperatures, typically in excess of 270 °C (518 °F).[citation needed]
Sodium-sulfur battery and lithium sulfur battery comprise two of the more advanced systems of the molten salt batteries. The NaS battery has reached a more advanced developmental stage than its lithium counterpart; it is more attractive since it employs cheap and abundant electrode materials. Thus the first commercial battery produced was the sodium-sulfur battery which used liquid sulfur for the positive electrode and a ceramic tube of beta-alumina solid electrolyte (BASE) for the electrolyte. Corrosion of the insulators was found to be a problem in the harsh chemical environment as they gradually became conductive and the self-discharge rate increased. A further problem of dendritic-sodium growth in Na/S batteries led to the development of the ZEBRA battery.
ZEBRA battery
Molten salt battery
Primary cells
Referred to as thermal batteries the electrolyte is solid and inactive at normal ambient temperatures. Thermally activated (“thermal”) batteries were conceived by the Germans during WW II and were used in the V-2 rockets. Dr. Georg Otto Erb is credited with developing the molten-salt battery that used the heat of the rocket to keep the salt liquid during its mission. The technology was brought back to the United States in 1946 and was immediately adapted to replace the troublesome liquid-based systems that had previously been used in artillery proximity fuzes. These batteries have been used for ordnance applications (e.g., proximity fuzes) since World War II and, subsequent to that, in nuclear weapons. They are the primary power source for many missiles such as the AIM-9 Sidewinder, MIM-104 Patriot, BGM-71 TOW, BGM-109 Tomahawk and others. In these batteries the electrolyte is immobilized when molten by a special grade of magnesium oxide that holds it in place by capillary action. This powdered mixture is pressed into pellets to form a separator between the anode and cathode of each cell in the battery stack. As long as the electrolyte (salt) is solid, the battery is inert and remains inactive. Each cell also contains a pyrotechnic heat source which is used to heat the cell to the typical operating temperature of 400 - 550C.
There are two types of design. One uses a fuze strip (containing barium chromate and powdered zirconium metal in a ceramic paper) along the edge of the heat pellets to initiate burning. The fuze strip is typically fired by an electrical igniter or squib by application of electric current through it. The second design uses a center hole in the middle of the battery stack into which the high-energy electrical igniter fires a mixture of hot gases and incandescent particles. The center-hole design allows much faster activation times (tens of milliseconds) vs. hundreds of milliseconds for the edge-strip design. Battery activation can also be accomplished by a percussion primer, similar to a shotgun shell. It is desired that the pyrotechnic source be gasless. The standard heat source typically consist of mixtures of iron powder and potassium perchlorate in weight ratios of typically 88/12, 86/14, and 84/16. The higher the potassium perchorate level, the higher the heat output (nominally 200, 259, and 297 calories/gram, respectively).
This property of unactivated storage has the double benefit of avoiding deterioration of the active materials during storage and at the same time it eliminates the loss of capacity due to self-discharge until the battery is called into use. They can thus be stored indefinitely (over 50 years) yet provide full power in an instant when it is required. Once activated, they provide a high burst of power for a short period (a few tens of seconds) to over 60 minutes or more, with power output ranging from a few watts to several kilowatts. The high power capability is due to the very high ionic conductivity of the molten salt, which is three orders of magnitude or more greater than that of sulfuric acid in a lead-acid car battery. Older thermal batteries used calcium or magnesium anodes, with cathodes of calcium chromate or vanadium or tungsten oxides, but lithium-alloy anodes replaced these in the 1980s, with lithium-silicon alloys being favored over the older lithium-aluminum alloys. The corresponding cathode for use with the lithium-alloy anodes is mainly iron disulfide (pyrite) with cobalt disulfide being used for high-power applications. The electrolyte is normally a eutectic mixture of lithium chloride and potassium chloride. More recently, other lower-melting, eutectic electrolytes based on lithium bromide, potassium bromide, and lithium chloride or lithium fluoride have also been used to provide longer operational lifetimes; they are also better conductors. The so-called "all-lithium" electrolyte based on lithium chloride, lithium bromide, and lithium fluoride (no potassium salts) is also used for high-power applications, because of its high ionic conductivity.
These batteries are used almost exclusively for military applications ie "one-shot" weapons such as guided missiles. However, the same technology was also studied by Argonne National Laboratories in the 1980s for possible use in electric vehicles, since the technology is rechargeable.
A radioisotope thermal generator, e.g. pellets of 90SrTiO4, can be used for long-term delivery of heat for the battery after activation, keeping it in molten state.[1]
Secondary cells
Since the mid-1960s much development work has been undertaken on rechargeable batteries using sodium (Na) for the negative electrodes. Sodium is attractive because of its high reduction potential of -2.71 volts, its low weight, its non-toxic nature, its relative abundance and ready availability and its low cost. In order to construct practical batteries, the sodium must be used in liquid form. Since the melting point of sodium is 98 °C (208 °F) this means that sodium based batteries must operate at high temperatures, typically in excess of 270 °C (518 °F).[citation needed]
Sodium-sulfur battery and lithium sulfur battery comprise two of the more advanced systems of the molten salt batteries. The NaS battery has reached a more advanced developmental stage than its lithium counterpart; it is more attractive since it employs cheap and abundant electrode materials. Thus the first commercial battery produced was the sodium-sulfur battery which used liquid sulfur for the positive electrode and a ceramic tube of beta-alumina solid electrolyte (BASE) for the electrolyte. Corrosion of the insulators was found to be a problem in the harsh chemical environment as they gradually became conductive and the self-discharge rate increased. A further problem of dendritic-sodium growth in Na/S batteries led to the development of the ZEBRA battery.
ZEBRA battery
Molten salt battery
ZEBRA Ni-NaCl2 battery, Museum Autovision, Altlußheim, Germany
Energy/weight 90 Wh/kg[1]
Energy/size 160 Wh/l[1]
Power/weight 155 W/kg,
peak power 335 C [2]
Energy/consumer-price 3.33 Wh/US$
Self-discharge rate 18%/day
Time durability >8 years
Cycle durability ~3000 cycles
Nominal cell voltage 2.58 V
The ZEBRA battery operates at 250 °C (482 °F) and utilizes molten sodium chloroaluminate (NaAlCl4), which has a melting point of 157 °C (315 °F), as the electrolyte. The negative electrode is molten sodium. The positive electrode is nickel in the discharged state and nickel chloride in the charged state. Because nickel and nickel chloride are nearly insoluble in neutral and basic melts, intimate contact is allowed, providing little resistance to charge transfer. Since both NaAlCl4 and Na are liquid at the operating temperature, a sodium-conducting β-alumina ceramic is used to separate the liquid sodium from the molten NaAlCl4. This battery was invented in 1985 by the Zeolite Battery Research Africa Project (ZEBRA) group led by Dr. Johan Coetzer at the Council for Scientific and Industrial Research (CSIR) in Pretoria, South Africa, hence the name ZEBRA battery. In 2009, the battery had been under development for more than 20 years. The technical name for the battery is Na-NiCl2 battery.
The ZEBRA battery has an attractive specific energy and power (90 Wh/kg and 150 W/kg). For comparison, LiFePO4 lithium iron phosphate batteries store 90–110 Wh/kg and the more common LiCoO2 lithium ion batteries store 150–200 Wh/kg. Nano Lithium-Titanate Batteries store energy and power of (116 Wh & 72 Wh/kg) and (1,250 W & 760 W/kg)[3]. The ZEBRA's liquid electrolyte freezes at 157 °C (315 °F), and the normal operating temperature range is 270 °C (518 °F) to 350 °C (662 °F). The β-alumina solid electrolyte that has been developed for this system is very stable, both to sodium metal and the sodium chloroaluminate. The primary elements used in the manufacture of ZEBRA batteries, Na, Cl and Al have much higher worldwide reserves and annual production than the Li used in Li-ion batteries.[4] Lifetimes of over 1500 cycles and five years have been demonstrated with full-sized batteries, and over 3000 cycles and eight years with 10- and 20-cell modules. Vehicles powered by ZEBRA batteries have covered more than 2 million km. Modec Electric Van uses ZEBRA batteries for the 2007 model. The Th!nk City also uses ZEBRA batteries.[5]
When not in use, ZEBRA batteries are typically left under charge so that they will remain molten and be ready for use when needed. If shut down and allowed to solidify, a reheating process must be initiated that may require up to two days to restore the battery pack to the desired temperature and impart a full charge. This reheating time varies depending on the state-of-charge of the batteries at the time of their shut down, battery-pack temperature, and power available for reheating. After a full shut down of the battery pack, three to four days will usually elapse before a fully-charged battery pack loses enough energy to cool and solidify.
Mercury battery
A mercury battery (also called mercuric oxide battery, or mercury cell) is a non-rechargeable electrochemical battery, a primary cell. Due to the content of mercury, and the resulting environmental concerns, the sale of mercury batteries is banned in many countries. Both ANSI and IEC have withdrawn standards for mercury batteries. Mercury batteries were made in button types for watches and calculators, and in larger forms for other applications.
Chemistry
Mercury batteries use either pure mercuric oxide or a mix of mercuric oxide with manganese dioxide as the cathode. Mercuric oxide is a non-conductor so some graphite is mixed with it; the graphite also helps prevent collection of mercury into large droplets. The anode is made of zinc and separated from the cathode with a layer of paper or other porous material soaked with electrolyte. During discharge, zinc oxidizes to zinc oxide and mercuric oxide gets reduced to elementary mercury. A little extra mercuric oxide is put into the cell to prevent evolution of hydrogen gas at the end of life. Mercury batteries are very similar to silver-oxide batteries.
Sodium hydroxide or potassium hydroxide are used as an electrolyte. Sodium hydroxide cells have nearly constant voltage at low discharge currents, making them ideal for hearing aids, calculators, and electronic watches. Potassium hydroxide cells, in turn, provided constant voltage at higher currents, making them suitable for applications requiring current surges, e.g. photographic cameras with flash, and watches with a backlight. Potassium hydroxide cells also have better performance at lower temperatures. Mercury cells have very long shelf life, up to 10 years.
A different form of mercury battery uses mercuric oxide and cadmium. This has a much lower terminal voltage around 0.9 volts and so has lower energy density, but it has an extended temperature range, in special designs up to 180 C.[3][4]
Electrical characteristics
Mercury batteries using mercury(II) oxide cathode have a very flat discharge curve, holding constant 1.35 V (open circuit) voltage until about last 5% of their lifetime, when their voltage drops rapidly. The voltage remains within 1% for several years at light load, and over a wide temperature range, making mercury batteries useful as a reference voltage in electronic instruments and in photographic light meters. Mercury batteries with cathodes made of a mix of mercuric oxide and manganese dioxide have output voltage of 1.4 V and more sloped discharge curve.
Substitutes
The ban on sale of mercury oxide batteries caused numerous problems for photographers, whose equipment frequently relied on their advantageous discharge curves and long lifetime. Alternatives used are zinc-air batteries, with similar discharge curve but much shorter lifetime (a few months) and poor performance in dry climates, alkaline batteries with voltage widely varying through their lifetime, and silver-oxide batteries with higher voltage (1.55 V) and very flat discharge curve, making them possibly the best, though expensive, replacement. Special adapters with a voltage dropping germanium diode are available, to adapt silver oxide batteries for use in older equipment designed for mercury batteries, such as cameras and light meters which require a stable, exact voltage.
Chemistry
Mercury batteries use either pure mercuric oxide or a mix of mercuric oxide with manganese dioxide as the cathode. Mercuric oxide is a non-conductor so some graphite is mixed with it; the graphite also helps prevent collection of mercury into large droplets. The anode is made of zinc and separated from the cathode with a layer of paper or other porous material soaked with electrolyte. During discharge, zinc oxidizes to zinc oxide and mercuric oxide gets reduced to elementary mercury. A little extra mercuric oxide is put into the cell to prevent evolution of hydrogen gas at the end of life. Mercury batteries are very similar to silver-oxide batteries.
Sodium hydroxide or potassium hydroxide are used as an electrolyte. Sodium hydroxide cells have nearly constant voltage at low discharge currents, making them ideal for hearing aids, calculators, and electronic watches. Potassium hydroxide cells, in turn, provided constant voltage at higher currents, making them suitable for applications requiring current surges, e.g. photographic cameras with flash, and watches with a backlight. Potassium hydroxide cells also have better performance at lower temperatures. Mercury cells have very long shelf life, up to 10 years.
A different form of mercury battery uses mercuric oxide and cadmium. This has a much lower terminal voltage around 0.9 volts and so has lower energy density, but it has an extended temperature range, in special designs up to 180 C.[3][4]
Electrical characteristics
Mercury batteries using mercury(II) oxide cathode have a very flat discharge curve, holding constant 1.35 V (open circuit) voltage until about last 5% of their lifetime, when their voltage drops rapidly. The voltage remains within 1% for several years at light load, and over a wide temperature range, making mercury batteries useful as a reference voltage in electronic instruments and in photographic light meters. Mercury batteries with cathodes made of a mix of mercuric oxide and manganese dioxide have output voltage of 1.4 V and more sloped discharge curve.
Substitutes
The ban on sale of mercury oxide batteries caused numerous problems for photographers, whose equipment frequently relied on their advantageous discharge curves and long lifetime. Alternatives used are zinc-air batteries, with similar discharge curve but much shorter lifetime (a few months) and poor performance in dry climates, alkaline batteries with voltage widely varying through their lifetime, and silver-oxide batteries with higher voltage (1.55 V) and very flat discharge curve, making them possibly the best, though expensive, replacement. Special adapters with a voltage dropping germanium diode are available, to adapt silver oxide batteries for use in older equipment designed for mercury batteries, such as cameras and light meters which require a stable, exact voltage.
Lithium battery
Lithium batteries are disposable (primary) batteries that have lithium metal or lithium compounds as an anode. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V to about 3.7 V, over twice the voltage of an ordinary zinc-carbon battery or alkaline cell battery[1] . Lithium batteries are widely used in products such as portable consumer electronic devices.
Disassembled CR2032 battery From left - negative cup from inner side with layer of lithium (I made few scratches and on air oxidizes in few seconds), separator(porous material), cathode (manganese dioxide), metal grid - current collector, metal casing (+)(damaged during opening the cell), on the bottom is plastic sealing ring
Lemon battery
A lemon battery is a device used in experiments proposed in many science textbooks around the world.[1] It is made by inserting two different metallic objects, for example a galvanized nail and a copper coin, into a lemon. The copper coin serves as the positive electrode or cathode and the galvanized nail as the electron-producing negative electrode or anode. These two objects work as electrodes, causing an electrochemical reaction which generates a small potential difference.
Overview
The aim of this experiment is to show students how batteries work. After the battery is assembled, a multimeter can be used to check the generated voltage. In order for a more visible effect to be produced, a few lemon cells connected in series can be used to power a standard LED. Flashlight bulbs are generally not used because the lemon battery cannot produce the amount of current required to light such bulbs. Digital clocks can work well, and some toymakers offer small kits with a clock that can be powered by two potatoes or lemons.
4 Lemon Circuit 2.8V LED Diagram
Earth battery
History
One of the earliest examples of an earth battery was built by Alexander Bain in 1841 in order to drive a prime mover.[1] Bain buried plates of zinc and copper in the ground about one meter apart and used the resulting voltage, of about one volt, to operate a clock. Carl Friedrich Gauss, who had researched Earth's magnetic field, and Karl A. von Steinheil, who built one of the first electric clocks and developed the idea of an "Earth return" or "ground return", had previously investigated such devices. The Leclanche battery was a copy of the earth battery. [2]
Daniel Drawbaugh received U.S. Patent 211,322 for an Earth battery for electric clocks (with several improvements in the art of Earth batteries). Another early patent was obtained by Emil Jahr U.S. Patent 690,151 Method of utilizing electrical Earth currents). In 1875, James C. Bryan received U.S. Patent 160,152 for his Earth Battery. In 1885, George Dieckmann, received US patent U.S. Patent 329,724 for his Electric Earth battery. In 1898, Nathan Stubblefield [3] received U.S. Patent 600,457 for his electrolytic coil battery, which was a combination of an earth battery and a solenoid. (For more information see US patents 155209, 182802, 495582, 728381, 3278335, 3288648, 4153757 and 4457988.) The Earth battery, in general, generated power for early telegraph transmissions and formed part of a tuned circuit that amplified the signalling voltage over long distances.
Operation and use
The simplest earth batteries consist of conductive plates from different locations in the electropotential series, buried in the ground so that the soil acts as the electrolyte in a voltaic cell. As such, the device acts as a non-rechargeable battery. When operated only as electrolytic devices, the devices were not continuously reliable, owing to drought condition. These devices were used by early experimenters as energy sources for telegraphy. However, in the process of installing long telegraph wires, engineers discovered that there were electrical potential differences between most pairs of telegraph stations, resulting from natural electrical currents (called telluric currents[4]) flowing through the ground. Some early experimenters did recognize that these currents were, in fact, partly responsible for extending the earth batteries' high outputs and long lifetimes. Later, experimenters would utilize these currents alone and, in these systems, the plates became polarized.
It had been long known that continuous electric currents flowed through the solid and liquid portions of the Earth[5], and the collection of current from an electrically conductive medium in the absence of electrochemical changes (and in the absence of a thermoelectric junction) was established by Lord Kelvin.[6][7] Lord Kelvin's "sea battery" was not a chemical battery.[7] Lord Kelvin observed that such variables as placement of the electrodes in the magnetic field and the direction of the medium's flow affected the current output of his device. Such variables do not affect battery operation. When metal plates are immersed in a liquid medium, energy can be obtained and generated,[8] including (but not limited to) methods known via magneto-hydrodynamic generators. In the various experiments by Lord Kelvin, metal plates were symmetrically perpendicular to the direction of the medium's flow and were carefully placed with respect to a magnetic field which differentially deflected electrons from the flowing stream. The electrodes can be asymmetrically oriented with respect to the source of energy, though.
To obtain the natural electricity, experimenters would thrust two metal plates into the ground at a certain distance from each other in the direction of a magnetic meridian, or astronomical meridian. The stronger currents flow from south to north. This phenomenon possesses a considerable uniformity of current strength and voltage. As the Earth currents flow from south to north, electrodes are positioned, beginning in the south and ending in the north, to increase the voltage at as large a distance as possible.[9] In many early implementations, the cost was prohibitive because of an over-reliance on extreme spacing between electrodes.
It has been found that all the common metals behave relatively similarly. The two spaced electrodes, having a load in an external circuit connected between them, are disposed in an electrical medium, and energy is imparted to the medium in such manner that "free electrons" in the medium are excited. The free electrons then flow into one electrode to a greater degree than in the other electrode, thereby causing electric current to flow in the external circuit through the load. The current flows from that plate whose position in the electropotential series is near the negative end (such as palladium). The current produced is highest when the two metals are most widely separated from each other in the electropotential series, and when the material nearer the positive end is to the north, while that at the negative end is towards the south. The plates, one copper and another iron or carbon, are connected above ground by means of a wire with as little resistance as possible. In such an arrangement, the electrodes are not appreciably chemically corroded, even when they are in earth saturated with water, and are connected together by a wire for a long time.
It had been found that to strengthen the current, it was most advantageous to drive the northerly electropositive electrode deeper into the medium than the southerly electrode. The greatest currents and voltages were obtained when the difference in depth was such that a line joining the two electrodes was in the direction of the magnetic dip, or magnetic inclination. When the previous methods were combined, the current was tapped and utilized in any well-known manner.
In some cases, a pair of plates with differing electrical properties, and with suitable protective coatings, were buried below the ground. A protective or other coating covered each entire plate. A copper plate could be coated with powdered coke, a processed carbonaceous material. To a zinc plate, a layer of felt could be applied. To use the natural electricity, earth batteries fed electromagnets, the load, that were part of a motor mechanism.
Chromic acid cell
Chromic acid cell
The Chromic acid cell was a type of primary cell which used chromic acid as a depolarizer. The chromic acid was usually made by acidifying (with sulfuric acid) a solution of potassium dichromate. The old name for potassium dichromate was potassium bichromate and the cell was often called a Bichromate cell. This type of cell is now only of historical interest.
Construction
The main elements of the cell were:
Anode, zinc
Electrolyte, dilute sulfuric acid
Depolarizer, chromic acid
Cathode, carbon
The cell was made in two forms - the single-fluid type, attributed to Poggendorff and the two-fluid type, attributed to Fuller. In both cases, cell voltage was about 2 volts.
Poggendorff cell
The cell was set up in a long-necked glass bottle with a zinc plate located between two carbon plates. The electrolyte and depolarizer were mixed. The mixture would dissolve the zinc plate even when the cell was not in use, so there was a mechanism for lifting the zinc plate out of the liquid and storing it in the neck of the bottle.
Fuller cell
The cell was set up in a glass, or glazed earthenware, pot. This contained the chromic acid solution, the carbon plate and a porous pot. Inside the porous pot was dilute sulfuric acid, the zinc rod, and a small quantity of mercury. The mercury formed an amalgam with the zinc and this reduced "local action", i.e. unwanted dissolution of the zinc when the cell was not in use.
Bunsen cell
Bunsen cell
The Bunsen cell is a zinc-carbon primary cell (colloquially called a "battery") composed of a zinc anode in dilute sulfuric acid separated by a porous pot from a carbon cathode in nitric or chromic acid.
Cell details
Zn + H2SO4 + 2HNO3 → ZnSO4 + 2 H2O + 2 NO2↑
The cell is named after its inventor, German chemist Robert Wilhelm Bunsen, who improved upon the Grove cell by replacing Grove's platinum cathode with carbon in the form of pulverized coal and coke. Like Grove's battery, Bunsen's emitted noxious fumes.
Bunsen used this cell to extract metals from their salts by electrolysis, enabling him to isolate metallic magnesium for the first time.
Henri Moissan used a stack of 90 cells for the electrolysis of hydrogen fluoride to obtain the element fluorine for the first time.
Atomic battery
Atomic battery
The terms atomic battery, nuclear battery, tritium battery and radioisotope generator are used to describe a device which uses the emissions from a radioactive isotope to generate electricity. Like nuclear reactors they generate electricity from atomic energy, but differ in that they do not use a chain reaction. Compared to other batteries they are very costly, but have extremely long life and high energy density, and so they are mainly used as power sources for equipment that must operate unattended for long periods of time, such as spacecraft and automated scientific stations in remote parts of the world.
Nuclear battery technology began in 1913, when Henry Moseley first demonstrated the Beta Cell. The field received considerable research attention for applications requiring long-life power sources for space needs during the 50s and 60s. Over the years many types and methods have been developed. The scientific principles are well known, but modern nano-scale technology and new wide bandgap semiconductors have created new devices and interesting material properties not previously available.
Batteries using the energy of radioisotope decay to provide long-lived power (10–20 years) are being developed internationally. Conversion techniques can be grouped into two types: thermal and non-thermal. The thermal converters (whose output power is a function of a temperature differential) include thermoelectric and thermionic generators. The non-thermal converters (whose output power is not a function of a temperature difference) extract a fraction of the incident energy as it is being degraded into heat rather than using thermal energy to run electrons in a cycle. Atomic batteries usually have an efficiency of 0.1–5%. High efficiency betavoltaics have 6–8%.
Nuclear battery technology began in 1913, when Henry Moseley first demonstrated the Beta Cell. The field received considerable research attention for applications requiring long-life power sources for space needs during the 50s and 60s. Over the years many types and methods have been developed. The scientific principles are well known, but modern nano-scale technology and new wide bandgap semiconductors have created new devices and interesting material properties not previously available.
Batteries using the energy of radioisotope decay to provide long-lived power (10–20 years) are being developed internationally. Conversion techniques can be grouped into two types: thermal and non-thermal. The thermal converters (whose output power is a function of a temperature differential) include thermoelectric and thermionic generators. The non-thermal converters (whose output power is not a function of a temperature difference) extract a fraction of the incident energy as it is being degraded into heat rather than using thermal energy to run electrons in a cycle. Atomic batteries usually have an efficiency of 0.1–5%. High efficiency betavoltaics have 6–8%.
Thermal converters
Thermionic converter
A thermionic converter consists of a hot electrode which thermionically emits electrons over a space charge barrier to a cooler electrode, producing a useful power output. Caesium vapor is used to optimize the electrode work functions and provide an ion supply (by surface contact ionization) to neutralize the electron space charge.
Radioisotope thermoelectric generator
A thermoelectric converter connects pairs of thermocouples in series. Each thermocouple is formed by the junction of two dissimilar materials. One of each pair is heated and the other cooled. Metal thermocouples have low thermal-to-electrical efficiency. However, the carrier density and charge can be adjusted in semiconductor materials such as bismuth telluride and silicon germanium to achieve much higher conversion efficiencies.
Thermophotovoltaic cells
Thermophotovoltaic cells work by the same principles as a photovoltaic cell, except that they convert infrared light (rather than visible light) emitted by a hot surface, into electricity. Thermophotovoltaic cells have an efficiency slightly higher than thermoelectric couples and can be overlaid on thermoelectric couples, potentially doubling efficiency. The University of Houston TPV Radioisotope Power Conversion Technology development effort is aiming at combining thermophotovoltaic cell concurrently with thermocouples to provide a 3 to 4-fold improvement in system efficiency over current thermoelectric radioisotope generators.
Alkali-metal thermal to electric converter
The alkali-metal thermal to electric converter (AMTEC) is an electrochemical system which is based on the electrolyte used in the sodium-sulfur battery, sodium beta-alumina. The device is a sodium concentration cell which uses a ceramic, polycrystalline β-alumina solid electrolyte (BASE), as a separator between a high pressure region containing sodium vapor at 900 - 1300 K and a low pressure region containing a condenser for liquid sodium at 400 - 700 K. Efficiency of AMTEC cells has reached 16% in the laboratory and is predicted to approach 20%.
Non-thermal converters
Non-thermal converters extract a fraction of the nuclear energy as it is being degraded into heat. Their outputs are not functions of temperature differences as are thermoelectric and thermionic converters. Non-thermal generators can be grouped into three classes.
Direct charging generators
In the first type, the primary generators consists of a capacitor which is charged by the current of charged particles from a radioactive layer deposited on one of the electrodes. Spacing can be either vacuum or dielectric. Negatively charged beta particles or positively charged alpha particles, positrons or fission fragments may be utilized. Although this form of nuclear-electric generator dates back to 1913, few applications have been found in the past for the extremely low currents and inconveniently high voltages provided by direct charging generators. Oscillator/transformer systems are employed to reduce the voltages, then rectifiers are used to transform the AC power back to Direct Current.
English physicist H.G.J. Moseley constructed the first of these. Moseley’s apparatus consisted of a glass globe silvered on the inside with a radium emitter mounted on the tip of a wire at the center. The charged particles from the radium created a flow of electricity as they moved quickly from the radium to the inside surface of the sphere. As late as 1945 the Moseley model guided other efforts to build experimental batteries generating electricity from the emissions of radioactive elements.
Betavoltaics
Main article: Betavoltaics
In May 2005, a group including researchers from the University of Rochester and from the University of Toronto announced [1][2] a small battery powered by the beta-particle-emitting decay of tritium and positioned the product as suitable for pacemakers or low-current electrical household devices. The device gathers energy from the beta-particles that pass through a silicon diode, in a manner analogous to photovoltaic cells. This technique is called betavoltaics and has the potential to radically increase atomic battery efficiency and energy production densities.
Optoelectric
Main article: Optoelectric nuclear battery
An optolectric nuclear battery has also been proposed by researchers of the Kurchatov Institute in Moscow. A beta-emitter (such as technetium-99) would stimulate an excimer mixture, and the light would power a photocell. The battery would consist of an excimer mixture of argon/xenon in a pressure vessel with an internal mirrored surface, finely-divided Tc-99, and an intermittent ultrasonic stirrer, illuminating a photocell with a bandgap tuned for the excimer. The advantage of this design is that precision electrode assemblies are not needed, and most beta particles escape the finely-divided bulk material to contribute to the battery's net power.
Reciprocating Electromechanical Atomic Batteries
Main article: Radioisotope piezoelectric generator
Electromechanical atomic batteries use the build up of charge between two plates to pull one bendable plate towards the other, until the two plates touch, discharge, equalizing the electrostatic buildup, and spring back. The mechanical motion produced can be used to produce electricity through flexing of a piezoelectric material or through a linear generator. Milliwatts of power are produced in pulses depending on the charge rate, in some cases multiple times per second (35Hz).
Radioisotopes Used
Atomic batteries use radioisotopes that produce low energy beta particles or sometimes alpha particles of varying energies. Low energy beta particles are needed to prevent the production of high energy penetrating Bremsstrahlung radiation that would require heavy shielding. Radioisotopes such as tritium, nickel-63, promethium-147, and technetium-99 have been tested. Plutonium-238, curium-242, curium-244 and strontium-90 have been used.
Aluminium battery
Aluminium battery
Aluminium batteries or aluminum batteries are commonly known as aluminium-air batteries or Al-air batteries, since they produce electricity from the reaction of oxygen in the air with aluminium. They have one of the highest energy densities of all batteries, but they are not widely used because of previous problems with cost, shelf-life, start-up time and byproduct removal, which have restricted their use to mainly military applications. An electric vehicle with aluminium batteries could have potentially ten to fifteen times the range of lead-acid batteries with a far smaller total weight[1], at the cost of substantially increased system complexity.
Al-air are primary batteries, i.e. non-rechargeable. Once the aluminium anode is consumed by its reaction with atmospheric oxygen at a cathode immersed in a water-based electrolyte to form hydrated aluminium oxide, the battery will no longer produce electricity. However, it may be possible to mechanically recharge the battery with new aluminium anodes made from recycling the hydrated aluminium oxide. Such recycling will be essential if aluminium-air batteries are to be widely adopted.
Electrochemistry
The anode oxidation half-reaction is
Al + 3OH− → Al(OH)3 + 3e− + −2.31 V.
The cathode reduction half-reaction is
O2 + 2H2O + 4e− → 4OH− + +0.40 V.
The total reaction is
4Al + 3O2 + 6H2O → 4Al(OH)3 + 2.71 V.
About 1.2 volts potential difference is created by these reactions, and is achievable in practice when potassium hydroxide is used as the electrolyte. Saltwater electrolyte achieves approximately 0.7 volts per cell.
Aluminum based batteries
Different types of aluminium batteries had been investigated:
Aluminium-chlorine battery was patented by United States Air Force in the 1970s and designed mostly for military applications. They use aluminium anodes and chlorine on graphite substrate cathodes. Required elevated temperatures to be operational.
Aluminium-iodine secondary cell has been investigated by some Chinese researchers.
Aluminium-sulfur batteries worked on by American researchers with great claims, although it seems that they are still far from mass production. It's unknown if they are rechargeable.
Al-Fe-O, Al-Cu-O and Al-Fe-OH batteries were proposed by some researchers for military hybrid vehicles. Corresponding practical energy densities claimed are 455, 440, and 380 Wh/kg
Alkaline battery
Alkaline battery
Alkaline batteries and alkaline cells (a battery being a collection of multiple cells) are a type of disposable battery or rechargeable battery dependent upon the reaction between zinc and manganese dioxide (Zn/MnO2).
Compared with zinc-carbon batteries of the Leclanché or zinc chloride types, while all produce approximately 1.5 volts per cell, alkaline batteries have a higher energy density and longer shelf-life. Compared with silver-oxide batteries, which alkalines commonly compete against in button cells, they have lower energy density and shorter lifetimes but lower cost.
The alkaline battery gets its name because it has an alkaline electrolyte of potassium hydroxide, instead of the acidic ammonium chloride or zinc chloride electrolyte of the zinc-carbon batteries which are offered in the same nominal voltages and physical size. Other battery systems also use alkaline electrolytes, but they use different active materials for the electrodes.
Chemistry
In an alkaline battery, the anode (negative terminal) is made of zinc powder (which allows more surface area for increased rate of reaction therefore increased electron flow) and the cathode (positive terminal) is composed of manganese dioxide. Alkaline batteries are comparable to zinc-carbon batteries, but the difference is that alkaline batteries use potassium hydroxide (KOH) as an electrolyte rather than ammonium chloride or zinc chloride.
The half-reactions are:[1]
Zn (s) + 2OH− (aq) → ZnO (s) + H2O (l) + 2e−
2MnO2 (s) + H2O (l) + 2e− →Mn2O3 (s) + 2OH− (aq)
Capacity
Capacity of an alkaline battery is larger than an equal size Leclanché or zinc-chloride cell because the manganese dioxide anode material is purer and denser, and space taken up by internal components such as current collectors is less. An alkaline cell can provide between three and five times as much operating time.[2]
The capacity of an alkaline battery is strongly dependent on the load. An AA-sized alkaline battery might have an effective capacity of 3000 mAh at low power, but at a load of 1000 mA, which is common for digital cameras, the capacity could be as little as 700 mAh.[3] The voltage of the battery declines steadily during use, so the total usable capacity depends on the cut-off voltage of the application. Unlike Leclanche cells the alkaline cell delivers about as much capacity on intermittent or continuous light loads. On a heavy load, capacity is reduced on continuous discharge compared with intermittent discharge, but the reduction is less than for Leclanche cells.
Voltage
The nominal voltage of a fresh alkaline cell is 1.5 V. Multiple voltages may be achieved with series of cells. The effective zero-load voltage of a non discharged alkaline battery varies from 1.50 to 1.65 V, depending on the chosen manganese dioxide and the contents of zinc oxide in the electrolyte. The average voltage under load depends on discharge and varies from 1.1 to 1.3 V. The fully discharged cell has a remaining voltage in the range of 0.8 to 1.0 V.
Current
The amount of current an alkaline battery can deliver is roughly proportional to its physical size. This is a result of decreasing internal resistance as the internal surface area of the cell increases. A general rule of thumb is that an AA alkaline battery can deliver 700 mA without any significant heating. Larger cells, such as C and D cells, can deliver more current. Applications requiring high currents of several amperes, such as high powered flashlights and portable stereos, will require D-sized cells to handle the increased load.
Construction
Alkaline batteries are manufactured in standardized cylindrical forms interchangeable with zinc-carbon batteries, and in button forms. Several individual cells may be interconnected to form a true "battery", such as those sold for use with flashlights and the 9 volt transistor-radio battery.[4]
A cylindrical cell is contained in a drawn steel can, which is the cathode current collector. The cathode mixture is a compressed paste of manganese dioxide with carbon powder added for increased conductivity. The paste may be pressed into the can or deposited as pre-molded rings. The hollow center of the cathode is lined with a separator, which prevents mixing of the anode and cathode materials and short-circuiting of the cell. The separator is made of a non-woven layer of cellulose or a synthetic polymer. The separator must conduct ions and remain stable in the highly alkaline electrolyte solution.
The anode is composed of a dispersion of zinc powder in a gel containing the potassium hydroxide electrolyte. To prevent gassing of the cell at the end of its life, more manganese dioxide is used than required to react with all the zinc.
When describing standard AAA,AA, C, sub-C and D size cells, the anode is connected to the flat end while the cathode is connected to the end with the raised button.
Recharging of alkaline batteries
Main article: Recharging alkaline batteries
Some alkaline batteries are designed to be recharged (see rechargeable alkaline battery), but most are not. Attempts to recharge may cause rupture, or the leaking of hazardous liquids which will corrode the equipment.
Leaks
Leaked alkaline battery
Over time, alkaline batteries are prone to leaking potassium hydroxide, a caustic agent that can cause respiratory, eye and skin irritation [5] This can be avoided by not attempting to recharge disposable alkaline cells, not mixing different battery types in the same device, replacing all of the batteries at the same time, storing in a dry place, and removing batteries for storage of devices.
Once a leak has formed due to corrosive penetration of the outer steel shell, potassium hydroxide forms a feathery crystalline structure that grows and spreads out from the battery over time, following up metal electrodes to circuit boards where it commences oxidation of copper traces and other components, leading to permanent circuitry damage.
The leaking crystalline growths can also emerge from seams around battery covers to form a furry coating outside the device, that then damages objects in contact with the leaking device such as varnish on wood shelves, and then oxidation and graying of the wood itself.
Disposal
When introduced in the 1960s, alkaline batteries contained a small amount of mercury amalgam to control side reactions at the zinc cathode. Improvements in the purity and consistency of materials have allowed manufacturers to reduce the mercury content in modern cells.[6] Unlike other types of batteries, alkaline batteries are allowed to be disposed of as regular domestic waste in some locations. This, however, is not environmentally friendly.[7][8] For example the state of California has deemed all batteries as hazardous waste when discarded, and has banned the disposal of batteries with other domestic waste.[9] In the US, one company shreds and separates the battery case metals, manganese and zinc.[1] Another company mixes batteries in as a feedstock in steel making furnaces, to make low-grade steel such as rebar; the zinc fumes are recovered separately.[2] In Europe battery disposal is controlled by the WEEE regulations, and as such alkaline batteries must not be thrown in with domestic waste. They should be disposed through local recycling stations/waste dumps. In the EU most stores which sell batteries (i.e. supermarkets) are required by law to accept old batteries for recycling.
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