Lithium iron phosphate battery
Encyclopedia
The lithium iron phosphate (LiFePO4) battery, also called LFP battery, is a type of rechargeable battery
, specifically a lithium-ion battery, which uses LiFePO4
as a cathode
material.
's research group at the University of Texas in 1996, as a cathode material for rechargeable lithium batteries. Because of its low cost, non-toxicity, the high abundance of iron, its excellent thermal stability, safety characteristics, good electrochemical performance, and high specific capacity (170 mA·h
/g
, or 610 C/g
) it gained some market acceptance.
The key barrier to commercialization was its intrinsically low electrical conductivity. This problem, however, was then overcome partly by reducing the particle size and effectively coating the LiFePO4 particles with conductive materials such as carbon, and partly by employing the doping
approaches developed by Yet-Ming Chiang and his coworkers at MIT
using cations of materials such as aluminium
, niobium
, and zirconium
. It was later shown that most of the conductivity improvement was due to the presence of nanoscopic carbon originating from organic precursors. Products using the carbonized and doped nanophosphate materials developed by Chiang are now in high volume mass production and are used in industrial products by major corporations including Black and Decker's DeWalt
brand, the Fisker Karma
, Daimler, Cessna
and BAE Systems
.
Most lithium-ion batteries (Li-ion) used in consumer electronics products are lithium cobalt oxide
batteries (LiCoO2). Other varieties of lithium-ion batteries include lithium manganese oxide (LiMn2O4) and lithium nickel oxide (LiNiO2). The batteries are named after the material used for their cathodes; the anodes are generally made of carbon and a wide variety of electrolytes are used.
However, one key advantage over other lithium-ion batteries is the superior thermal and chemical stability, which provides better safety characteristics than lithium-ion batteries with other cathode materials. Due to significantly stronger bonds between the oxygen atoms in the phosphate (compared to the cobalt), oxygen is not readily released, and as a result, lithium iron phosphate cells are virtually incombustible in the event of mishandling during charge or discharge, and can handle high temperatures without decomposing.
Lithium iron phosphate chemistry also offers a longer cycle life over standard lithium-ion cells.
The use of phosphates also reduces the cost and environmental concerns of Cobalt cells, particularly in regards of cobalt entering the environment through improper disposal, with considerably increased safety over the cobalt chemistry type of lithium battery cell, particularly when compared to LiPo battery cells commonly used in the aeromodeling hobby.
One of the other major advantages for LiFePO4 when compared with LiCoO2 is higher current or peak-power rating.
LFP batteries have some drawbacks:
While LiFePO4 cells have lower voltage and energy density
than LiCoO2 Li-ion cells, this disadvantage is offset over time by the slower rate of capacity loss (aka greater calendar-life) of LiFePO4 when compared with other lithium-ion battery chemistries (such as LiCoO2 cobalt or LiMn2O4 manganese spinel based lithium-ion polymer batteries or lithium-ion batteries). For example:
-P
-O
bond is stronger than the Co
-O
bond, so that when abused, (short-circuited, overheated, etc.) the oxygen atoms are much harder to remove. This stabilization of the redox energies also helps fast ion migration.
As lithium migrates out of the cathode in a LiCoO2 cell, the CoO2 undergoes non-linear expansion that affects the structural integrity of the cell. The fully lithiated and unlithiated states of LiFePO4 are structurally similar which means that LiFePO4 cells are more structurally stable than LiCoO2 cells.
No lithium remains in the cathode of a fully charged LiFePO4 cell—in a LiCoO2 cell, approximately 50% remains in the cathode. LiFePO4 is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells.
(walking) vehicle.
Lithium Technology Corp. announced in May 2007, that they had developed a new Lithium Iron Phosphate battery with cells large enough for use in hybrid cars, claiming they are "the largest cells of their kind in the world.". While they may be large enough for such uses, there remain limitations to the use of this particular Lithium battery technology which may make their use contraindicated. See Advantage and Disadvantages above for details.
This battery is used in the electric cars made by Aptera and QUICC.
Killacycle
, the worlds fastest electric motorcycle, uses lithium iron phosphate batteries.
Roehr Motorcycle Company
, uses a 5.8 kW·h capacity LFP battery pack to power its supersport electric motorcycle.
This type of battery technology is used on the One Laptop per Child (OLPC) project. OLPC batteries are manufactured by BYD Company
of Shenzhen, China, the world's largest producer of Li-ion batteries. BYD
, also a car manufacturer, plans to use its lithium iron phosphate batteries to power its PHEV, the F3DM
and F6DM
(Dual Mode), which will be the first commercial dual-mode electric car in the world. It plans to mass produce the cars in 2009.
One Laptop per Child uses LFP batteries in its XO laptops because they contain no toxic heavy metals in compliance with the European Union's Restriction of Hazardous Substances Directive
.
LFP batteries are gaining popularity now in the world of hobby-grade R/C, due to the benefits over the ever-popular LiPo batteries. They can be recharged much faster and for more cycles, are not prone to catching fire or exploding while recharging, and are more robust than the LiPo type.
LFP batteries are used by electric vehicles manufacturer Smith Electric Vehicles to power its products.
Used by Minneapolis Electric Bike and Chicago Electric Bicycles.
Some electronic cigarette modifications also use these types of batteries.
Rechargeable battery
A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible. Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to...
, specifically a lithium-ion battery, which uses LiFePO4
Lithium iron phosphate
Lithium iron phosphate , also known as LFP, is a compound used in lithium iron phosphate batteries . It is targeted for use in power tools and electric vehicles...
as a cathode
Cathode
A cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
material.
History
LiFePO4 was discovered by John GoodenoughJohn B. Goodenough
John Bannister Goodenough is an American professor and prominent solid-state physicist. He is currently a professor of mechanical engineering and materials science at the University of Texas at Austin...
's research group at the University of Texas in 1996, as a cathode material for rechargeable lithium batteries. Because of its low cost, non-toxicity, the high abundance of iron, its excellent thermal stability, safety characteristics, good electrochemical performance, and high specific capacity (170 mA·h
Ampere-hour
An ampere-hour or amp-hour is a unit of electric charge, with sub-units milliampere-hour and milliampere second...
/g
Gram
The gram is a metric system unit of mass....
, or 610 C/g
Gram
The gram is a metric system unit of mass....
) it gained some market acceptance.
The key barrier to commercialization was its intrinsically low electrical conductivity. This problem, however, was then overcome partly by reducing the particle size and effectively coating the LiFePO4 particles with conductive materials such as carbon, and partly by employing the doping
Doping (semiconductor)
In semiconductor production, doping intentionally introduces impurities into an extremely pure semiconductor for the purpose of modulating its electrical properties. The impurities are dependent upon the type of semiconductor. Lightly and moderately doped semiconductors are referred to as extrinsic...
approaches developed by Yet-Ming Chiang and his coworkers at MIT
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
using cations of materials such as aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
, niobium
Niobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...
, and zirconium
Zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...
. It was later shown that most of the conductivity improvement was due to the presence of nanoscopic carbon originating from organic precursors. Products using the carbonized and doped nanophosphate materials developed by Chiang are now in high volume mass production and are used in industrial products by major corporations including Black and Decker's DeWalt
DeWALT
DeWalt is a worldwide brand of power tools for the construction, manufacturing and woodworking industries. It is a subsidiary of Stanley Black & Decker.- History :...
brand, the Fisker Karma
Fisker Karma
The Fisker Karma is a plug-in hybrid luxury sports sedan produced by Fisker Automotive and manufactured at Valmet Automotive in Finland. The United States Environmental Protection Agency rated the Karma's combined city/highway fuel economy at equivalent in all-electric mode, and at in...
, Daimler, Cessna
Cessna
The Cessna Aircraft Company is an airplane manufacturing corporation headquartered in Wichita, Kansas, USA. Their main products are general aviation aircraft. Although they are the most well known for their small, piston-powered aircraft, they also produce business jets. The company is a subsidiary...
and BAE Systems
BAE Systems
BAE Systems plc is a British multinational defence, security and aerospace company headquartered in London, United Kingdom, that has global interests, particularly in North America through its subsidiary BAE Systems Inc. BAE is among the world's largest military contractors; in 2009 it was the...
.
Most lithium-ion batteries (Li-ion) used in consumer electronics products are lithium cobalt oxide
Lithium cobalt oxide
Lithium cobalt oxide is a chemical compound commonly used in the positive electrodes of lithium-ion batteries. The structure of LiCoO2 is known theoretically and has been confirmed with techniques like x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS: it consists of...
batteries (LiCoO2). Other varieties of lithium-ion batteries include lithium manganese oxide (LiMn2O4) and lithium nickel oxide (LiNiO2). The batteries are named after the material used for their cathodes; the anodes are generally made of carbon and a wide variety of electrolytes are used.
Advantages and disadvantages
The LiFePO4 battery uses a lithium-ion-derived chemistry and shares many of its advantages and disadvantages with other Lithium-ion battery chemistries.However, one key advantage over other lithium-ion batteries is the superior thermal and chemical stability, which provides better safety characteristics than lithium-ion batteries with other cathode materials. Due to significantly stronger bonds between the oxygen atoms in the phosphate (compared to the cobalt), oxygen is not readily released, and as a result, lithium iron phosphate cells are virtually incombustible in the event of mishandling during charge or discharge, and can handle high temperatures without decomposing.
Lithium iron phosphate chemistry also offers a longer cycle life over standard lithium-ion cells.
The use of phosphates also reduces the cost and environmental concerns of Cobalt cells, particularly in regards of cobalt entering the environment through improper disposal, with considerably increased safety over the cobalt chemistry type of lithium battery cell, particularly when compared to LiPo battery cells commonly used in the aeromodeling hobby.
One of the other major advantages for LiFePO4 when compared with LiCoO2 is higher current or peak-power rating.
LFP batteries have some drawbacks:
- The energy density (energy/volume) of a new LFP battery is somewhat lower than that of a new LiCoO2 battery. (14% reduction in energy density) Battery manufacturers across the world are currently working to find ways to maximize the energy storage performance and reduce size & weight.
- Many brands of LFPs have a low discharge rate compared with lead-acid or LiCoO2. Since discharge rate is a percentage of battery capacity this can be overcome by using a larger battery (more ampère-hours). However, A123Systems claims 100C pulse discharge rate.
While LiFePO4 cells have lower voltage and energy density
Energy density
Energy density is a term used for the amount of energy stored in a given system or region of space per unit volume. Often only the useful or extractable energy is quantified, which is to say that chemically inaccessible energy such as rest mass energy is ignored...
than LiCoO2 Li-ion cells, this disadvantage is offset over time by the slower rate of capacity loss (aka greater calendar-life) of LiFePO4 when compared with other lithium-ion battery chemistries (such as LiCoO2 cobalt or LiMn2O4 manganese spinel based lithium-ion polymer batteries or lithium-ion batteries). For example:
- After one year on the shelf, a LiFePO4 cell typically has approximately the same energy density as a LiCoO2 Li-ion cell.
- Beyond one year on the shelf, a LiFePO4 cell is likely to have higher energy density than a LiCoO2 Li-ion cell due to the differences in their respective calendar-lives.
Specifications
- Cell voltage = min. discharge voltage = 2.8 V. Working voltage = . Max. charge voltage = 3.6 V.
- Volumetric energy densityEnergy densityEnergy density is a term used for the amount of energy stored in a given system or region of space per unit volume. Often only the useful or extractable energy is quantified, which is to say that chemically inaccessible energy such as rest mass energy is ignored...
= 220 WhWatt-hourThe kilowatt hour, or kilowatt-hour, is a unit of energy equal to 1000 watt hours or 3.6 megajoules.For constant power, energy in watt hours is the product of power in watts and time in hours...
/dm3Litér- External links :*...
(790 kJ/dm3) - Gravimetric energy density = >90 Wh/kg (>320 J/g)
- 100% DODDepth of dischargeDepth of discharge is an alternate method to indicate a battery's state of charge . The DOD is the inverse of SOC: as one increases, the other decreases. While the SOC units are percent points , the units for DOD can be Ah or percent points...
cycle life (number of cycles to 80% of original capacity) = 2,000–7,000 - Cathode composition (weight)
- 90% C-LiFePO4, grade Phos-Dev-12
- 5% CarbonCarbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
EBNEBNEBN may refer to:* Emergency Broadcast Network, a "video-remix" group* EBN-OZN, a 1980s band* Evidence Based Nursing, a journal* Evidence-Based Nursing, a field of nursing and medical practice....
-10-10 (superior graphite) - 5% PVDF
- Cell Configuration
- Carbon-coatedCoatingCoating is a covering that is applied to the surface of an object, usually referred to as the substrate. In many cases coatings are applied to improve surface properties of the substrate, such as appearance, adhesion, wetability, corrosion resistance, wear resistance, and scratch resistance...
aluminium current collector 15 - 1.54 cm2 cathodeCathodeA cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
- ElectrolyteElectrolyteIn chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
: EC-DMC 1-1 LiClO4Lithium perchlorateLithium perchlorate is the inorganic compound with the formula LiClO4. This white or colourless crystalline salt is noteworthy for its high solubility in many solvents. It exists both in anhydrous form and as a trihydrate.-Uses:...
1M - AnodeAnodeAn anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....
: Metallic lithiumLithiumLithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
- Carbon-coated
- Experimental conditions:
- Room temperatureRoom temperature-Comfort levels:The American Society of Heating, Refrigerating and Air-Conditioning Engineers has listings for suggested temperatures and air flow rates in different types of buildings and different environmental circumstances. For example, a single office in a building has an occupancy ratio per...
- Voltage limits:
- Charge: Up to C/1 rate up to 3.6 V, then constant voltage at 3.6 V until I < C/24
- Room temperature
Safety
LiFePO4 is an intrinsically safer cathode material than LiCoO2 and manganese spinel. The FeIron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
-P
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
-O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
bond is stronger than the Co
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
-O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
bond, so that when abused, (short-circuited, overheated, etc.) the oxygen atoms are much harder to remove. This stabilization of the redox energies also helps fast ion migration.
As lithium migrates out of the cathode in a LiCoO2 cell, the CoO2 undergoes non-linear expansion that affects the structural integrity of the cell. The fully lithiated and unlithiated states of LiFePO4 are structurally similar which means that LiFePO4 cells are more structurally stable than LiCoO2 cells.
No lithium remains in the cathode of a fully charged LiFePO4 cell—in a LiCoO2 cell, approximately 50% remains in the cathode. LiFePO4 is highly resilient during oxygen loss, which typically results in an exothermic reaction in other lithium cells.
Usage
LFP batteries were featured on the November 5, 2008 episode of Prototype This!. They were used as the power source for a hexapodHexapod (robotics)
A six-legged walking robot should not be confused with a Stewart platform, a kind of parallel manipulator used in robotics applications.A hexapod robot is a mechanical vehicle that walks on six legs. Since a robot can be statically stable on three or more legs, a hexapod robot has a great deal of...
(walking) vehicle.
Lithium Technology Corp. announced in May 2007, that they had developed a new Lithium Iron Phosphate battery with cells large enough for use in hybrid cars, claiming they are "the largest cells of their kind in the world.". While they may be large enough for such uses, there remain limitations to the use of this particular Lithium battery technology which may make their use contraindicated. See Advantage and Disadvantages above for details.
This battery is used in the electric cars made by Aptera and QUICC.
Killacycle
Killacycle
The KillaCycle is an electrically powered motorcycle purpose-built for drag racing. It was built and is managed by a small motorworks team owned and run by Bill Dubé...
, the worlds fastest electric motorcycle, uses lithium iron phosphate batteries.
Roehr Motorcycle Company
Roehr Motorcycle Company
Roehr Motorcycle Company is a US motorcycle manufacturer based Gurnee, Illinois.-History:In 1995 Walter Roehrich began construction of the 500 cc two stroke v-twin motorcycle, using Yamaha YZ250 engine parts on a prototype crankcase. The result was the 115 hp Roehr Rv500 that was shown to the...
, uses a 5.8 kW·h capacity LFP battery pack to power its supersport electric motorcycle.
This type of battery technology is used on the One Laptop per Child (OLPC) project. OLPC batteries are manufactured by BYD Company
BYD Company
BYD Co Ltd is a Chinese manufacturer of automobiles and rechargeable batteries based in Shenzhen, Guangdong province.Hailed for its innovations, BYD has grown to become a major manufacturer of rechargeable batteries, most notably mobile phone batteries....
of Shenzhen, China, the world's largest producer of Li-ion batteries. BYD
BYD Auto
BYD Automobile Co Ltd is a Chinese automobile manufacturer based in Shenzhen, Guangdong Province...
, also a car manufacturer, plans to use its lithium iron phosphate batteries to power its PHEV, the F3DM
BYD F3DM
The BYD F3DM is a plug-in hybrid compact sedan manufactured by BYD Auto with an all-electric range of and a hybrid electric powertrain that can extend the range an additional . The F3DM is the world's first mass produced plug-in hybrid automobile and went on sale to government agencies and...
and F6DM
BYD F6DM
The BYD F6DM is a planned plug-in hybrid mid-size sedan. A planned fully electric version was called F6e. The manufacturer, Chinese automaker BYD Auto, is owned by BYD Company Limited, China's largest mobile phone battery maker...
(Dual Mode), which will be the first commercial dual-mode electric car in the world. It plans to mass produce the cars in 2009.
One Laptop per Child uses LFP batteries in its XO laptops because they contain no toxic heavy metals in compliance with the European Union's Restriction of Hazardous Substances Directive
Restriction of Hazardous Substances Directive
The Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment 2002/95/EC was adopted in February 2003 by the European Union. The RoHS directive took effect on 1 July 2006, and is required to be enforced and become law in each member state...
.
LFP batteries are gaining popularity now in the world of hobby-grade R/C, due to the benefits over the ever-popular LiPo batteries. They can be recharged much faster and for more cycles, are not prone to catching fire or exploding while recharging, and are more robust than the LiPo type.
LFP batteries are used by electric vehicles manufacturer Smith Electric Vehicles to power its products.
Used by Minneapolis Electric Bike and Chicago Electric Bicycles.
Some electronic cigarette modifications also use these types of batteries.
See also
- Lithium batteryLithium batteryLithium batteries are disposable 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 battery...
- Lithium-ion battery
- Lithium-titanate batteryLithium-titanate batteryThe lithium–titanate battery is a type of rechargeable battery, which has the advantage of being faster to charge than other lithium-ion batteries. Some analysts speculate that lithium–titanate batteries will power electric cars of the future....
- Lithium–air battery
- Lithium-ion polymer battery
- Nanowire batteryNanowire batteryA nanowire battery is a lithium-ion battery invented by a team led by Dr. Yi Cui at Stanford University in 2007. The team's invention consists of a stainless steel anode covered in silicon nanowires, to replace the traditional graphite anode...
- PhosphatePhosphateA phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
- Power-to-weight ratioPower-to-weight ratioPower-to-weight ratio is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power sources...
- VanadiumVanadiumVanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...