A nickel metal hydride battery, abbreviated NiMH, is a type of rechargeable battery similar to a nickel-cadmium (NiCd) battery but has a hydrogen-absorbing alloy for the anode instead of cadmium. Like in NiCd batteries, nickel is the cathode. A NiMH battery can have two to three times the capacity of an equivalent size NiCd and the memory effect is not as significant. However, compared to the lithium-ion battery, the volumetric energy density is lower and self-discharge is higher. The watt-hour (symbol W·h) is a unit of energy. ... KG, kg or Kg can refer to several things: Kilogram, the SI base unit of mass. ... The watt-hour (symbol W·h) is a unit of energy. ... The watt-hour (symbol W·h) is a unit of energy. ... The United States dollar is the official currency of the United States. ... It has been suggested that secondary cell be merged into this article or section. ... The nickel-cadmium battery (commonly abbreviated NiCd and pronounced nye-cad) is a popular type of rechargeable battery for portable electronics and toys using the metals nickel (Ni) and cadmium (Cd) as the active chemicals. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Standard atomic weight 58. ... General Name, Symbol, Number cadmium, Cd, 48 Chemical series transition metals Group, Period, Block 12, 5, d Appearance silvery gray metallic Standard atomic weight 112. ... An alloy is a homogeneous mixture of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... Diagram of a zinc anode in a galvanic cell. ... General Name, Symbol, Number cadmium, Cd, 48 Chemical series transition metals Group, Period, Block 12, 5, d Appearance silvery gray metallic Standard atomic weight 112. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Standard atomic weight 58. ... Diagram of a copper cathode in a Daniells cell. ... With batteries, the memory effect, also known as lazy battery effect, is an effect observed in some rechargeable batteries that causes them to hold less charge. ... Lithium-ion batteries (sometimes abbreviated Li-ion batteries) are a type of rechargeable battery commonly used in consumer electronics. ... Volume, also called capacity, is a quantification of how much space an object occupies. ... Energy density is the amount of energy stored in a given system or region of space per unit volume or per unit mass, depending on the context. ...

Common penlight-size (AA) batteries have nominal capacities C ranging from 1100 mA·h to 2700 mA·h at 1.2 V, usually rated at 0.2×C rate. Useful discharge capacity is an inverse function of the discharge rate, but up to around 1×C rate, there is no significant difference. An ampere-hour (abbreviated as A·h) is a unit of electrical charge. ...

The specific energy density for NiMH material is approximately 70 W·h/kg (250 kJ/kg), with a volumetric energy density of about 300 W·h/L (360 MJ/m³). Energy density is the amount of energy stored in a given system or region of space per unit volume or per unit mass, depending on the context. ... The watt-hour (symbol W·h) is a unit of energy. ... The kilogram or kilogramme (symbol: kg) is the SI base unit of mass. ... Energy density is the amount of energy stored in a given system or region of space per unit volume or per unit mass, depending on the context. ... The liter (spelled liter in American English and litre in Commonwealth English) is a unit of volume. ...

Modern, high capacity NiMH rechargeable batteries

Download high resolution version (600x800, 70 KB)nickel metal hydride batteries This is a copyrighted and/or trademarked logo. ... Download high resolution version (600x800, 70 KB)nickel metal hydride batteries This is a copyrighted and/or trademarked logo. ...

History

NiMH battery technology was developed at the end of the 1980s and commercialised first by the Matsushita Company ^{[citation needed]}. Logo for the Panasonic brand Matsushita Electric Industrial Co. ...

Applications

Applications of NiMH type batteries includes hybrid vehicles such as the Toyota Prius or Honda Insight/Civic and consumer electronics. The NiMH technology will also be used on the Alstom Citadis low floor tram ordered for Nice, France; as well as the humanoid prototype robot ASIMO designed by Honda. Standard NiMH batteries perform better with moderate drain devices such as digital cameras, flashlights, and other consumer electronics. Because NiCd batteries have lower internal resistance, they still have the edge in very high current drain applications such as cordless power tools and RC cars. A hybrid vehicle (HV) is a vehicle that uses two or more distinct power or fuel sources such as: An on-board rechargeable energy storage system (RESS) and a fueled power source (internal combustion engine) for vehicle propulsion Human or sail powered bicycle with battery assist A human-powered or... Toyota Motor Corporation ), or Toyota, is a Japanese multinational corporation and the worlds largest automaker by revenue (USD $212. ... Prius may refer to: Hitachi Flora Prius, a personal computer. ... This article or section does not adequately cite its references or sources. ... Civic can refer to multiple things: Civics, the science of comparative government Honda Civic, a small car produced by the Honda Motor Co. ... Consumer electronics is a term used to describe the category of electronic equipment intended for everyday use by people, the consumers. ... Alstom (formerly GEC-Alsthom) (Euronext: ALO) is a large French company whose businesses are power generation, railway signalling; and manufacturing trains (e. ... A Citadis 202 tram in Melbourne, Australia The Citadis is a low-floor tram built by Alstom in La Rochelle, France, and Barcelona, Spain. ... Passenger door of a low-floor tram Passenger door of a non-low-floor tram In public transportation, low floor is a term describing vehicles such as busses, trolleybusses and trams whose passenger compartment has a floor which is considerably lower than that of traditional cars. ... This article or section does not cite any references or sources. ... This article does not cite any references or sources. ... Press release photo of the most recent ASIMO model ASIMO ) is a humanoid robot created by Honda Motor Company. ... The logo of the Honda automobiles The logo of the Honda motorcycles Honda Motor Company, Limited )   (TYO: 7267 , NYSE: HMC), or simply called Honda, is a Japanese multinational corporation, engine manufacturer and engineering corporation. ... Look up drain in Wiktionary, the free dictionary. ... This article or section does not cite any references or sources. ... For the Soviet military jet with the NATO designation Flashlight, see Yakovlev Yak-25. ... The output impedance, source impedance, or internal impedance of an electronic device is the opposition exhibited by its output terminals to the flow of an alternating current (AC) of a particular frequency as a result of resistance, induction and capacitance. ... A power tool is a tool with a motor. ... Kyosho Inferno 1/8-scale buggy A radio controlled car is a powered model car driven from a distance by a hand-held radio transmitter which sends its control information to the cars onboard radio receiver. ...

Electrochemistry

The anode reaction occurring in a NiMH battery is as follows: H₂O + M + e⁻ ↔ OH⁻ + M-H The battery is charged in the right direction of this equation and discharged in the left direction. Diagram of a zinc anode in a galvanic cell. ...

Nickel(II) hydroxide forms the cathode. Nickel(II) hydroxide (Ni(OH)2) is an insoluble compound commonly used in rechargable battery electrodes. ... Diagram of a copper cathode in a Daniells cell. ...

The "metal" in the anode of a NiMH battery is actually an intermetallic compound. Many different compounds have been developed for this application, but those in current use fall into two classes. The most common is AB₅, where A is a rare earth mixture of lanthanum, cerium, neodymium, praseodymium and B is nickel, cobalt, manganese, and/or aluminum. Very few batteries use higher-capacity negative material electrodes based on AB₂ compounds, where A is titanium and/or vanadium and B is zirconium or nickel, modified with chromium, cobalt, iron, and/or manganese, due to the reduced life performances [2]. Diagram of a zinc anode in a galvanic cell. ... Intermetallics is concerned with all aspects of ordered chemical compounds between two or more metals and notably with their applications. ... Rare earth ore Rare earth elements and rare earth metals are trivial names sometimes applied to a collection of 17 chemical elements in the periodic table, namely scandium, yttrium, and the lanthanides. ... General Name, Symbol, Number lanthanum, La, 57 Chemical series lanthanides Group, Period, Block 3, 6, f Appearance silvery white Atomic mass 138. ... General Name, Symbol, Number cerium, Ce, 58 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white Atomic mass 140. ... General Name, Symbol, Number neodymium, Nd, 60 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance silvery white, yellowish tinge Standard atomic weight 144. ... General Name, Symbol, Number praseodymium, Pr, 59 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance grayish white Standard atomic weight 140. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Standard atomic weight 58. ... wikipedia sucks big balls For other uses, see Cobalt (disambiguation). ... General Name, Symbol, Number manganese, Mn, 25 Chemical series transition metals Group, Period, Block 7, 4, d Appearance silvery metallic Standard atomic weight 54. ... Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ... General Name, Symbol, Number vanadium, V, 23 Chemical series transition metals Group, Period, Block 5, 4, d Appearance silver-grey metal Standard atomic weight 50. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Standard atomic weight 91. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6, 4, d Appearance silvery metallic Standard atomic weight 51. ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ...

Any of these compounds serves the same role, reversibly forming a mixture of metal hydride compounds. When hydrogen ions are forced out of the potassium hydroxide electrolyte solution by the voltage applied during charging, this process prevents them from forming a gas, allowing a low pressure and volume to be maintained. As the battery is discharged, these same ions are released to participate in the reverse reaction. Hydronium is the common name for the cation H3O+. Nomenclature According to IUPAC ion nomenclature, it should be referred to as oxonium. ... The chemical compound potassium hydroxide, (KOH) sometimes known as caustic potash, potassa, potash lye, and potassium hydrate, is a metallic base. ... An electrolyte is a substance containing free ions that behaves as an electrically conductive medium. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas colored yellow An ion is an atom or group of atoms which have lost or gained one or more electrons, making them negatively or positively charged. ...

NiMH batteries have an alkaline electrolyte, usually potassium hydroxide. The common (Arrhenius) definition of a base is a chemical compound that either donates hydroxide ions or absorbs hydrogen ions when dissolved in water. ... An electrolyte is a substance containing free ions that behaves as an electrically conductive medium. ... The chemical compound potassium hydroxide, (KOH) sometimes known as caustic potash, potassa, potash lye, and potassium hydrate, is a metallic base. ...

Charging

NIMH Charge curve

The charging voltage is 1.4-1.6 V/cell.[3] Duracell recommends "a maintenance charge of indefinite duration at C/300 rate". A fully charged cell measures 1.35-1.4 V (unloaded), and supplies a nominal average 1.2V during discharge, down to about 1.0V (further discharge may cause permanent damage). Image File history File links Charge_NiMH.svg‎ Illustration de linfluence de la vitesse de charge sur la tension pour un accumilateur NIMH File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Nickel metal hydride battery ... Image File history File links Charge_NiMH.svg‎ Illustration de linfluence de la vitesse de charge sur la tension pour un accumilateur NIMH File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Nickel metal hydride battery ... A pair of Duracell AAA batteries. ...

Voltage Depression ("Memory Effect") from repeated partial discharge can occur, but is reversible through charge cycling.^[1] With batteries, the memory effect, also known as lazy battery effect, is an effect observed in some rechargeable batteries that causes them to hold less charge. ... With batteries, the memory effect, also known as lazy battery effect, is an effect observed in some rechargeable batteries that causes them to hold less charge. ...

When fast-charging, it is advisable to charge the NiMH batteries with a smart battery charger to avoid overcharging, which can damage batteries and cause dangerous conditions. Modern NiMH batteries contain catalysts to immediately deal with gases developed as a result of over-charging without being harmed (2 H₂ + O₂ ---catalyst--> 2 H₂O). However, this only works with overcharging currents of up to C/10 h (nominal capacity divided by 10 hours). As a result of this reaction, the batteries will heat up considerably, marking the end of the charging process. Some quick chargers have a fan to keep the batteries cool. This charger charges the battery until it reaches a specific voltage and then it trickle charges the battery until it is removed. ... Four double-A (AA) rechargeable cells A Duracell AA alkaline cell In science and technology, a galvanic cell is an electrochemical cell that stores chemical energy and makes it available in an electrical form, and a battery is a string of two or more cells in series. ... It has been suggested that this article or section be merged into Catalysis. ... Four double-A (AA) rechargeable cells A Duracell AA alkaline cell In science and technology, a galvanic cell is an electrochemical cell that stores chemical energy and makes it available in an electrical form, and a battery is a string of two or more cells in series. ... In electricity, current refers to electric current, which is the flow of electric charge. ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ...

A method for very rapid charging called In-Cell Charge Control involves an internal pressure switch in the cell, which disconnects the charging current in the event of overpressure. I-C3 or In-Cell Charge Control is a method for very rapid charging of NiMH batteries, patented by Rayovac. ...

Some equipment manufacturers consider that NiMH can be safely charged in simple fixed (low) current chargers with or without timers, and that permanent overcharging is permissible with currents up to C/10 h. In fact, this is what happens in cheap cordless phone base stations and the cheapest battery chargers. Although this may be safe, it may not be good for the health of the battery. According to the Panasonic NiMH charging manual (link below), permanent trickle charging (small current overcharging) can cause battery deterioration and the trickle charge rate should be limited to between 0.033×C per hour and 0.05×C per hour for a maximum of 20 hours to avoid damaging the batteries. A portable phone or cordless phone is a wireless telephone which is associated with a fixed telephone landline (POTS) and can only be operated close to (typically less than 100 metres of) its base station, such as in and around the house. ... This charger charges the battery until it reaches a specific voltage and then it trickle charges the battery until it is removed. ... Panasonic is an international brand name for Japanese electric products manufacturer Matsushita Electric Industrial Co. ... Most rechargeable batteries, particularly nickel-cadmium batteries or nickel metal hydride batteries, have a moderate rate of self discharge, meaning they gradually lose their charge even if they are not used in a device. ...

Long-term maintenance charge of NiMH batteries needs to be by low duty cycle pulses of high current rather than continuous low current in order to preserve battery health. In telecommunication and electronics, the term duty cycle has the following meanings: The duty cycle D is defined as the ratio between the pulse duration () and the period (T) of a rectangular waveform In a periodic phenomenon, the ratio of the duration of the phenomenon in a given period to...

Brand new batteries, or batteries which have been unused for some time, need "reforming" to reach their full capacity. For this reason new batteries may need several charge/discharge cycles before they operate to their advertised capacity.

Discharging

Care must also be taken during discharge to ensure that one or more cells in a series-connected battery pack, like the common arrangement of four AA cells in series in a digital camera, do not become completely discharged and go into polarity reversal. Cells are never absolutely identical, and inevitably one will be completely discharged before the others. When this happens, the "good" cells will start to "drive" the discharged cell in reverse, which can cause permanent damage to that cell. Some cameras, GPS receivers and PDAs detect the safe end-of-discharge voltage of the series cells and shut themselves down, but devices like flashlights and some toys do not. Once noticeable dimming or slowing of the device is noticed, it should be turned off immediately to avoid polarity reversal. A single cell driving a load won't suffer from polarity reversal, because there are no other cells to reverse-charge it when it becomes discharged. A battery pack is a set of any number of (preferably) identical batteries or individual battery cells. ... ‹ The template below (Expand) is being considered for deletion. ... This article or section does not cite any references or sources. ... Reverse Charging is when a rechargeable battery is recharged with its polarity (plus/minus) reversed. ... The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). ... User with PDA Personal digital assistants (PDAs) are handheld computers that were originally designed as personal organizers, but became much more versatile over the years. ...

Self-discharge

NiMH has a somewhat higher self-discharge rate than NiCd in the past, which is no more true at present time. The self-discharge is 5-10% on the first day^{[citation needed]}, and stabilizes around 0.5-1% per day at room temperature. This is not a problem in the short term, but makes them unsuitable for many light-duty uses, such as clocks, remote controls or safety devices, where the battery would normally be expected to last many months or years. The rate is strongly affected by the temperature at which the batteries are stored with cooler storage temperatures leading to slower discharge rate and longer battery life. The highest capacity cells on the market (> 2700mAh) are reported to have the highest discharge rates. Self-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes. ... Room temperature describes a certain temperature within enclosed space that is uses for various purposes by human beings. ...

Low Self Discharge Batteries

A new type of nickel metal hydride battery was introduced in 2006 that claims to reduce self-discharge, and therefore lengthen shelf life. By using a new separator, manufacturers claim between 70 to 85% of capacity is retained after one year, when stored at 20 degrees Celsius (68F). These cells are marketed as "ready-to-use" rechargeables, and are targeted towards typical consumers who use their digital cameras only a few times a year. Besides the longer shelf life, they are otherwise similar to normal NiMH batteries of equivalent capacity, and can be charged in typical NiMH chargers. Some brands that are currently available on the market (May 2007) are Accupower Acculoop, Ansmann MaxE range, Gold Peak ReCyko, Kodak Pre Charged, Nexcell EnergyOn, Panasonic R2, Rayovac Hybrid, Sanyo Eneloop, Titanium Power Enduro, Uniross Hybrio, and VARTA Ready2use. These appear to be available in AA and AAA sizes only, and have less capacity (2000~2100mAh in AA) than the current generation of high-capacity cells (2800mAh, AA). Gold Peak is a battery manufacturer established in 1964. ... ReCyko is a low self discharge nickel metal hydride battery made by Gold Peak. ... Eastman Kodak Company (NYSE: EK) is a large multinational public company producing photographic equipment. ... Rayovac (formerly known as Ray-O-Vac until 1988) is a battery maker based in Atlanta, Georgia, United States. ... Sanyo Electric Co. ... Sanyo Eneloop A low self discharge nickel metal hydride battery made by Sanyo, available in AA (2000 mAh) and AAA (800 mAh) sizes. ... Uniross is an international company, that started in 1968 in the United Kingdom. ... VARTA Automotive is the largest manufacturer of car batteries in Europe, and with its large range of products it offers the right battery for each vehicle. ...

Environment

Cadmium is poisonous, so NiMH batteries are less detrimental to the environment than NiCd batteries. The nickel-cadmium battery (commonly abbreviated NiCd or NiCad) is a popular type of rechargeable battery for portable electronics and toys. ...

Battery recycling programs exist to take care of end-of-life batteries. This article needs additional references or sources to facilitate its verification. ...

Another issue is the environmental impact of nickel mines. General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Standard atomic weight 58. ...

Comparison with other battery types

NiMH batteries and chargers are readily available in retail stores in common sizes: AAA, AA, C and D. An AAA battery is 44. ... ‹ The template below (Expand) is being considered for deletion. ... Four double-A batteries In science and technology, a battery is a device that stores energy and makes it available in an electrical form. ... Four double-A batteries In science and technology, a battery is a device that stores energy and makes it available in an electrical form. ...

They are not expensive, and the voltage and performance is similar to standard alkaline batteries in those sizes; they can be substituted for most purposes. The ability to recharge hundreds of times can save a lot of money and resources. Alkaline batteries A Duracell AA alkaline battery 2 Duracell-Brand AAA Alkaline batteries Alkaline batteries are a type of power cell dependent upon the reaction between zinc and manganese dioxide (Zn/MnO2). ...

They are often used in digital cameras and work well in this application. Applications that require frequent replacement of the battery, such as toys or video game controllers, also benefit from use of rechargeable batteries. With the development of low self discharge NiMHs (see section above), many occasional-use applications are candidates for NiMH rechargeables.

NiMH batteries are particularly advantageous for high current drain applications, due in large part to their low internal resistance. Alkaline batteries, which might have approximately 3000mAh capacity under low current demand (200mA), will have less than 1000mAh capacity under 1000mA (reference). Digital cameras with LCDs and flashlights can draw over 1A, quickly depleting Alkaline batteries after few shots. NiMH can handle these current levels and maintain their full capacity.

Sometimes, voltage-sensitive devices won't perform well because the voltage of NiMH batteries is lower than disposable batteries at equivalent sizes. Even though the voltage is lower, it can be beneficial for the length of the discharge cycle, since the low internal resistance allows NiMH cells to deliver a near-constant voltage until they are almost completely discharged. A disposable product is a product designed for cheapness and short-term convenience rather than medium to long-term durability, with most products only intended for single use. ...

Lithium ion batteries are more compact than nickel metal hydride batteries.^[2] Li-Ion Camera Battery Lithium ion batteries (or Li-ion) have become very common and dropped in price recently. ...

Security and Danger

Metal hydrides are relatively safe materials for energy storage. However, a seldom cycle reaction (Kühne effect) may lead to the pulverization and explosion of the metal hydride.

When hydrogen is absorbed by metals, then it forms bubbles around impurities and lattice defects of the metal. During their growth until a diameter of several micrometers, the bubbles deform the metal lattice and create mechanical stresses. After several hours, the mechanical stresses have become strong enough to create cracks which propagate through the metal lattice. The cracks are formed preferentially between the hydride bubbles and the weaker hydrided metal. Palladium dihydride is a semi-metal. Therefore the different electronegativities of metal and hydrogen generate positively electrically charged hydride bubble surfaces. Hence, the crack sides become electrically charged. Within the cracks of typically one micrometer width and ten to hundred micrometers length there arises an electric field strength of one hundred million volts per centimeter. Within strongly hydrided metals, electrons are bound stronger than hydrogen nuclei. Therefore the electric field within the cracks allows the hydrogen nuclei of the bubbles to accelerate until they reach energies of typically ten kilo-electron-volts. Within the weaker hydrided metal, the hydrogen nuclei transfer their kinetic energy of several kilo-electron-volts to the metal lattice during a path of one tenth of a micrometer. This energy transfer creates hot spots within the hydrided metal with a mean temperature of typically ten thousand degrees Celsius and a pressure of ten billion Pascal. Within the hot spots, the hydrided metal is gaseous. Because of the high internal pressure, the hot spots transfer their heat energy explosively to the surrounding solid hydrided metal, where the explosions generate further cracks. When such a crack collides with the surface of a hydrided bubble, then the electrically charged bubble surface generates a strong electric field within the crack. Again, the electric field accelerates hydrogen nuclei from the bubble until they get several kilo-electron-volts of energy. Hence, a cycle reaction of the creation of cracks, electric fields, kilo-electron-volt hydrogen nuclei, hot spots, and micro-explosions is generated. This cycle reaction might result in the pulverization and even explosion of the entire metal hydride.

References

• Bipolar Nickel Metal Hydride Battery by Martin G. Klein, Michael Eskra, Robert Plivelich and Paula Ralston
• The possible hot nature of cold fusion, by Rainer W. Kühne, in: Fusion Technology 25, 198-202 (1994)

1. ^ Voltage Depression ("Memory Effect"). Duracell.com. Retrieved on July 2007.
2. ^ Mitsubishi Heavy to make lithium ion car batteries. Yahoo finance, Singapore — quoting Reuters (23 January 2007). Retrieved on July 2007.

July 2007 is the seventh month of that year. ... is the 23rd day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... July 2007 is the seventh month of that year. ...

See also

External links

• BatteryUniversity.com
• Battery Care & Tips
• Duracell Ni-MH Technical Bulletin
• Energizer Ni-MH Battery Datasheets