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{{Essay-like|article|date=July 2009}}{{More footnotes|article|date=September 2009}}
{{chembox {{chembox
| Verifiedfields = changed
| verifiedrevid = 440630495
| Watchedfields = changed
| ImageFile = Lithium_iron_phosphateV2.png
| verifiedrevid = 450705077
| ImageFile1 = Atomic structure of olivine 1.png
| ImageFile2 = Lithium iron phosphate.svg
| ImageSize = | ImageSize =
| IUPACName = iron(2+) lithium phosphate (1:1:1) | IUPACName = iron(2+) lithium phosphate (1:1:1)
| OtherNames = | OtherNames =
| Section1 = {{Chembox Identifiers |Section1={{Chembox Identifiers
| Abbreviations = | Abbreviations =
| StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Fe.Li.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q+2;+1;/p-3 | StdInChI = 1S/Fe.Li.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q+2;+1;/p-3
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = GELKBWJHTRAYNV-UHFFFAOYSA-K | StdInChIKey = GELKBWJHTRAYNV-UHFFFAOYSA-K
| InChI = 1S/Fe.Li.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q+2;+1;/p-3 | InChI = 1S/Fe.Li.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q+2;+1;/p-3
| InChIKey1 = GELKBWJHTRAYNV-UHFFFAOYSA-K | InChIKey1 = GELKBWJHTRAYNV-UHFFFAOYSA-K
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| EINECS = | CASNo = 15365-14-7
| PubChem = | EINECS = 604-917-2
| PubChem = 15320824
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| ChemSpiderID = 10752170 | ChemSpiderID = 10752170
| SMILES = ..P()()=O | SMILES = ..P()()=O
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| Formula = {{chem|FeLiO|4|P}}
| ATC_Supplemental =
| MolarMass = 157.757
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| Appearance =
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| Density =
| Formula = FeLiO<sub>4</sub>P
| MolarMass = 157.757 | MeltingPt =
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'''Lithium iron phosphate''' ('''LiFePO<sub>4</sub>'''), also known as '''LFP''', is a compound used in ]<ref>“Phospho-olivines as Positive-Electrode Materials for Rechargeable Lithium Batteries” A. K. Padhi, K. S. Nanjundaswamy, and J. B. Goodenough, J. Electrochem. Soc., Volume 144, Issue 4, pp. 1188-1194 (April 1997)</ref> (related to ]). It is targeted for use in ]s and ]. It is also used in ] education laptops.


'''Lithium iron phosphate''' or '''lithium ferro-phosphate''' ('''LFP''') is an ] with the formula '''{{chem|LiFePO|4}}'''. It is a gray, red-grey, brown or black solid that is insoluble in water. The material has attracted attention as a component of ],<ref>Park, O. K.; Cho, Y.; Lee, S.; Yoo, H.-C.; Song, H.-K.; Cho, J., "Who Will Drive Electric Vehicles, Olivine or Spinel?", Energy Environ. Sci. 2011, volume 4, pages 1621-1633. {{doi|10.1039/c0ee00559b}}</ref> a type of ].<ref name="EngineeringIntegrations2021">{{cite book |last1=Chung |first1=Hsien-Ching |last2=Nguyen |first2=Thi Dieu Hien |last3=Lin |first3=Shih-Yang |last4=Li |first4=Wei-Bang |last5=Tran |first5=Ngoc Thanh Thuy |last6=Thi Han |first6=Nguyen |last7=Liu |first7=Hsin-Yi |last8=Pham |first8=Hai Duong |last9=Lin |first9=Ming-Fa |title=First-Principles Calculations for Cathode, Electrolyte and Anode Battery Materials |date=December 2021 |publisher=IOP Publishing |url=https://doi.org/10.1088/978-0-7503-4685-6ch16 |chapter=Chapter 16 - Engineering integrations, potential applications, and outlooks of Li-ion battery industry|doi=10.1088/978-0-7503-4685-6ch16 |isbn=978-0-7503-4685-6 }}</ref> This battery chemistry is targeted for use in ]s, ], solar energy installations<ref name="Batteries10(2024)202">{{cite journal |last1=Chung |first1=Hsien-Ching |title=The Long-Term Usage of an Off-Grid Photovoltaic System with a Lithium-Ion Battery-Based Energy Storage System on High Mountains: A Case Study in Paiyun Lodge on Mt. Jade in Taiwan |journal=Batteries |date=13 June 2024 |volume=10 |issue=6 |pages=202 |doi=10.3390/batteries10060202|doi-access=free |arxiv=2405.04225 }}</ref><ref>{{Cite web|title = New Energy Storage Startup to Take Hawaii Homes Off-Grid|url = http://www.hawaiiweblog.com/2015/07/06/blue-planet-energy-ion-battery|website = Hawaii Blog|accessdate = 2015-07-09|last = Ozawa|first = Ryan|date = 7 July 2015}}</ref> and more recently large ].<ref>{{Cite web|url=https://datacenterfrontier.com/google-looks-to-batteries-as-replacement-for-diesel-generators/#:~:text=The%20pilot%20project%20at%20Google%27s,Free%20Energy%20Lead%20at%20Google.|title = Google Looks to Batteries as Replacement for Diesel Generators|date = 16 December 2020}}</ref>{{r|EngineeringIntegrations2021}}
Most lithium batteries (Li-ion) used in 3C (computer, communication, consumer electronics) products are mostly ] (LiCoO<sub>2</sub>) batteries. Other lithium batteries include ] (LiMn<sub>2</sub>O<sub>4</sub>), ] (LiNiO<sub>2</sub>), and lithium iron phosphate (LFP). The cathodes of lithium batteries are made with the above materials, and the anodes are generally made of ].


Most lithium batteries (Li-ion) used in consumer electronics products use cathodes made of lithium compounds such as ] ({{chem|LiCoO|2}}), lithium manganese oxide ({{chem|LiMn|2|O|4}}), and lithium nickel oxide ({{chem|LiNiO|2}}). The ] are generally made of ].
Avoiding the lithium cobalt oxide cathode leads to a number of advantages. LiCoO<sub>2</sub> is one of the more expensive components of traditional li-ion batteries, giving LFP batteries the potential to ultimately become significantly cheaper to produce. LiCoO<sub>2</sub> is also toxic, while lithium iron phosphate is not. {{Citation needed|date=January 2010}} <!-- --~~~~ --> LiCoO<sub>2</sub> also can lead to problems with runaway overheating and outgassing, making batteries that use it more susceptible to fire than LFP batteries. This advantage means that LFP batteries don't need as intense charge monitoring as traditional li-ion. Lastly, LFP batteries tend to have lower (~60%) ] in comparison to traditional li-ion.


Lithium iron phosphate exists naturally in the form of the mineral ], but this material has insufficient purity for use in batteries.
==LiFePO<sub>4</sub> introduction==
Lithium iron phosphate (molecular formula is LiFePO<sub>4</sub>, also known as LFP), is used as cathode material for lithium-ion batteries (also called lithium iron phosphate battery). Its characteristic does not include noble elements such as cobalt, the price of raw material is lower and both phosphorus and iron are abundant on Earth which lowers raw material availability issues. The annual production of ] carbonate available to the automotive industry is estimated at only 30.000 tonnes in 2015.<ref></ref>


=={{chem|LiMPO|4}}==
==Principle==
With general chemical formula of {{chem|LiMPO|4}}, compounds in the {{chem|LiFePO|4}} family adopt the ] structure. M includes not only Fe but also Co, Mn and Ti.<ref>{{Cite journal|last1=Fedotov|first1=Stanislav S.|last2=Luchinin|first2=Nikita D.|last3=Aksyonov|first3=Dmitry A.|last4=Morozov|first4=Anatoly V.|last5=Ryazantsev|first5=Sergey V.|last6=Gaboardi|first6=Mattia|last7=Plaisier|first7=Jasper R.|last8=Stevenson|first8=Keith J.|last9=Abakumov|first9=Artem M.|last10=Antipov|first10=Evgeny V.|date=2020-03-20|title=Titanium-based potassium-ion battery positive electrode with extraordinarily high redox potential|journal=Nature Communications|language=en|volume=11|issue=1|page=1484|doi=10.1038/s41467-020-15244-6|pmid=32198379|pmc=7083823|bibcode=2020NatCo..11.1484F|issn=2041-1723|quote=LiTiPO4F|doi-access=free}}</ref> As the first commercial {{chem|LiMPO|4}} was C/{{chem|LiFePO|4}}, the whole group of {{chem|LiMPO|4}} is informally called “lithium iron phosphate” or “{{chem|LiFePO|4}}”. However, more than one olivine-type phase may be used as a battery's cathode material. Olivine compounds such as {{chem|A|''y''|MPO|4}}, {{chem|Li|1−''x''|MFePO|4}}, and {{chem|LiFePO|4−''z''|M}} have the same crystal structures as {{chem|LiMPO|4}}, and may replace it in a cathode. All may be referred to as “LFP”.{{Citation needed|reason=no source for generally calling various chemical formulas LFP, seems like an opinion and not fact|date=February 2024}}
Batteries using this cathode material have a moderate operating voltage (3.3V), high energy storage capacity (170mAh/g), high discharge power, fast charging and long cycle life, and its stability is also high when placed under high temperatures or in a high thermal environment. This seemingly ordinary but, in fact, revolutionary and novel cathode material for lithium-ion batteries belongs to the ''']''' group. The etymology of its mineral name – ''']''' - is from the ] ''tri'' (three) and ''phyllon'' (leaf). This mineral is gray, red-grey, brown, or black. Detailed information about this mineral can be found on the website .


Manganese, phosphate, iron, and lithium also form an ]. This structure is a useful contributor to the cathode of lithium rechargeable batteries.<ref>{{cite journal|last=Kim|first=Jongsoon|title=Thermal Stability of Fe-Mn Binary Olivine Cathodes for Li Rechargeable Batteries.|journal=Journal of Materials Chemistry|year=2012|volume=22|issue=24|page=11964|url=http://pubs.rsc.org/en/content/articlehtml/2012/JM/C2JM30733B|publisher=The Royal Society of Chemistry|doi=10.1039/C2JM30733B|accessdate=19 Oct 2012|url-access=subscription}}</ref> This is due to the olivine structure created when lithium is combined with manganese, iron, and phosphate (as described above). The olivine structures of lithium rechargeable batteries are significant, for they are affordable, stable, and can be safely used to store energy.<ref>Wang, J.; Sun, X., "Olivine Lifepo4: The Remaining Challenges for Future Energy Storage", Energy Environ. Sci. 2015, volume 8, pages 1110-1138. {{doi|10.1039/C4EE04016C}}</ref>
==Nomenclature of LiFePO<sub>4</sub>==
The correct chemical formula of LiFePO<sub>4</sub> is LiMPO<sub>4</sub>. LiFePO<sub>4</sub> has an olivine crystal structure. The M of the chemical formula refers to any metal, including Fe, Co, Mn, Ti, etc. The first commercial LiMPO<sub>4</sub> was C/LiFePO<sub>4</sub> and therefore, people refer to the whole group of LiMPO<sub>4</sub> as lithium iron phosphate, LiFePO<sub>4</sub>. However, more than one olivine compounds, in addition to LiMPO<sub>4</sub>, may be used as the cathode material of lithium iron phosphate. Such olivine compounds as AyMPO<sub>4</sub>, Li1-xMFePO<sub>4</sub>, and LiFePO<sub>4</sub>-zM have the same crystal structures as LiMPO<sub>4</sub> and may be used as the cathode material of lithium ion batteries. (All may be referred to as “LFP”.)


==Invention of LFP== ==History and production==
] and ] first identified the ] class of cathode materials for ].<ref>{{cite journal |last1=Masquelier |first1=Christian |last2=Croguennec |first2=Laurence |title=Polyanionic (Phosphates, Silicates, Sulfates) Frameworks as Electrode Materials for Rechargeable Li (or Na) Batteries |doi=10.1021/cr3001862 |journal=Chemical Reviews |volume=113 |issue=8 |pages=6552–6591 |year=2013|pmid=23742145 }}</ref><ref>{{Cite journal | last1 = Manthiram | first1 = A. | last2 = Goodenough | first2 = J. B. | doi = 10.1016/0378-7753(89)80153-3 | title = Lithium insertion into Fe<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> frameworks | journal = Journal of Power Sources | volume = 26 | issue = 3–4 | pages = 403–408 | year = 1989 | bibcode = 1989JPS....26..403M }}</ref><ref>{{Cite journal | last1 = Manthiram | first1 = A. | last2 = Goodenough | first2 = J. B. | doi = 10.1016/0022-4596(87)90242-8 | title = Lithium insertion into Fe<sub>2</sub>(MO<sub>4</sub>)<sub>3</sub> frameworks: Comparison of M = W with M = Mo | journal = Journal of Solid State Chemistry | volume = 71 | issue = 2 | pages = 349–360 | year = 1987 | bibcode = 1987JSSCh..71..349M | doi-access = free }}</ref> {{chem|LiFePO|4}} was then identified as a cathode material belonging to the polyanion class for use in batteries in 1996 by Padhi et al.<ref>"{{chem|LiFePO|4}}: A Novel Cathode Material for Rechargeable Batteries", A.K. Padhi, K.S. Nanjundaswamy, J.B. Goodenough, Electrochemical Society Meeting Abstracts, '''96-1''', May, 1996, pp 73</ref><ref>“Phospho-olivines as Positive-Electrode Materials for Rechargeable Lithium Batteries” A. K. Padhi, K. S. Nanjundaswamy, and J. B. Goodenough, J. Electrochem. Soc., Volume 144, Issue 4, pp. 1188–1194 (April 1997)</ref> Reversible extraction of lithium from {{chem|LiFePO|4}} and insertion of lithium into {{chem|FePO|4}} was demonstrated. ] confirmed that LFP was able to ensure the security of large input/output current of lithium batteries.<ref>Nature Materials, 2008, 7, 707-711.</ref>
LiFePO<sub>4</sub> was invented and reported by Akshaya Padhi of John Goodenough's group at University of Texas at Austin in 1996<ref>"LiFePO<sub>4</sub>: A Novel Cathode Material for Rechargeable Batteries", A.K. Padhi, K.S. Nanjundaswamy, J.B. Goodenough, Electrochimical Society Meeting Abstracts, '''96-1''', May, 1996, pp 73</ref> as an excellent candidate for the cathode of rechargeable lithium battery that is inexpensive, nontoxic, and environmentally benign. The reversible extraction of lithium from LiFePO<sub>4</sub> and insertion of lithium into FePO<sub>4</sub> was demonstrated. The subsequent R&D in the electrochemical energy storage all over the globe has been geared to overcoming the processing and engineering challenges that has led to current use LiFePO<sub>4</sub> in rechargeable lithium batteries.


The material can be produced by heating a variety of iron and lithium salts with phosphates or ]. Many related routes have been described including those that use ].<ref>{{Cite journal| doi = 10.1016/j.jpowsour.2009.01.074| issn = 0378-7753| volume = 190| issue = 2| pages = 538–544| last1 = Jugović| first1 = Dragana| last2 = Uskoković| first2 = Dragan| title = A review of recent developments in the synthesis procedures of lithium iron phosphate powders| journal = Journal of Power Sources| accessdate = | date = 2009-05-15| url =http://itn.sanu.ac.rs/opus4/files/1199/Jugovic%20et%20al_revised%20manuscript_doi_10%201016_jjpowsour200901074.pdf| bibcode = 2009JPS...190..538J}}</ref>
==Theory behind LFP ==
This lithium battery’s cathode material of olivine composition is already being mass produced by several up source professional material manufacturers. It is expected to widely expand the applications in the field of lithium batteries, and take it to the new fields such as electric bicycles, gas-electric hybrid vehicles and automation vehicles; In Tokyo Japan, a research group led by Professor Atsuo Yamada of Tokyo University of Technology, published a report on August 11, 2008 issue of “natual materials” which included the following statement: the lithium-ion iron phosphate battery will be used as the power source for environmental-friendly electric cars, which have great future prospects. The Tokyo University of Technology and North East University research group is led by Professor Atsuo Yamada. The group uses neutron irradiation phosphate iron, and then analyzes the interaction between neutron and materials to study the motion status of lithium-ion in iron phosphate. The researchers concluded that in the lithium iron phosphate, lithium-ion extended in accordance with a certain straight direction, has a different motion pattern with the existing lithium-ion electrode materials such as cobalt. This is a coincidence with the original assume theory, the analysis results with the use of neutron diffraction, confirms that lithium iron phosphate (molecular formula is LiFePO<sub>4</sub>, also known as LFP) is able to ensure the security of large input/output current of lithium battery.


==The Physical and Chemical Properties of LFP== ==Physical and chemical properties==
In {{chem|LiFePO|4}}, lithium has a +1 charge, iron +2 charge balancing the −3 charge for phosphate. Upon removal of Li, the material converts to the ferric form {{chem|FePO|4}}.<ref name= Love>{{cite journal|title=Review of {{chem|LiFePO|4}} phase transition mechanisms and new observations from X-ray absorption spectroscopy|author1=Love, Corey T.|author2=Korovina, Anna|author3=Patridge, Christopher J.|author4=Swider-Lyons|author5=Karen E.|author6=Twigg, Mark E.|author7=Ramaker, David E.|journal= Journal of the Electrochemical Society|year=2013|volume=160|issue=5|pages=A3153–A3161|doi=10.1149/2.023305jes|doi-access=free}}</ref>
The chemical formula of lithium iron phosphate is LiFePO<sub>4</sub>, in which lithium has +1 valence, iron has +2 valence and phosphate has -3 valence. The central iron atom together with its surrounding 6 oxygen atoms forms a corner-shared octahedron - FeO<sub>6</sub> - with iron in the center. The phosphorus atom of the phosphate forms with the four oxygen atoms an edge-shared tetrahedron - PO<sub>4</sub> - with phosphorus in the center. A zigzag three-dimensional framework is formed by FeO<sub>6</sub> octahedra sharing common-O corners with PO<sub>4</sub> tetrahedra. Lithium ions reside within the octahedral channels in a zigzag structure. In the lattice, FeO<sub>6</sub> octahedra are connected by sharing the corners of the bc face. LiO<sub>6</sub> groups form a linear chain of edge-shared octahedra parallel to the b axis. A FeO<sub>6</sub> octahedron shares edges with two LiO<sub>6</sub> octahedra and one PO<sub>4</sub> tetrahedron. In crystallography, this structure is thought to be the Pmnb space group of the orthorhombic crystal system. The lattice constants are: a=6.008A, b=10.334A, and c=4.693A. The volume of the unit lattice is 291.4 A3. The phosphates of the crystal stabilize the whole framework and give LFP good thermal stability and excellent cycling performances.


The iron atom and 6 oxygen atoms form an ], described as {{chem|FeO|6}}, with the Fe ion at the center. The phosphate groups, {{chem|PO|4}}, are tetrahedral. The three-dimensional framework is formed by the {{chem|FeO|6}} octahedra sharing O corners. Lithium ions reside within the octahedral channels in a zigzag manner. In ], this structure is thought to belong to the P<sub>mnb</sub> space group of the ] crystal system. The ] are: ''a'' = 6.008&nbsp;Å, ''b'' = 10.334&nbsp;Å, and ''c'' = 4.693&nbsp;Å. The volume of the ] is 291.4&nbsp;Å<sup>3</sup>.
Different from the two traditional cathode materials - LiMnO<sub>4</sub> and LiCoO<sub>2</sub>, lithium ions of LiMPO<sub>4</sub> move in the one-dimensional free volume of the lattice. During charge/discharge, the lithium ions are extracted from/inserted into LiMPO<sub>4</sub> while the central iron ions are oxidized/reduced. This extraction/insertion process is reversible. LiMPO<sub>4</sub> has, in theory, a charge capacity of 170mAh/g and a stable open-circuit voltage of 3.45V. The insertion/extraction reaction of the lithium ions is shown below: LiFe(II)PO<sub>4</sub> <-> Fe(III)PO<sub>4</sub> + Li + e- (1)


In contrast to two traditional cathode materials, {{chem|LiMnO|4}} and {{chem|LiCoO|2}}, lithium ions of {{chem|LiFePO|4}} migrate in the lattice's one-dimensional free volume. During charge/discharge, the lithium ions are extracted concomitant with oxidation of Fe:
The extraction of lithium from LiFePO<sub>4</sub> produces FePO<sub>4</sub> with similar structures. FePO<sub>4</sub> also has a Pmnb space group. The lattice constants of FePO<sub>4</sub> are a=5.792A, b=9.821A and c=4.788A. The volume of the unit lattice is 272.4 A3. Extraction of lithium ions reduces the lattice volume, as is the case of lithium oxides. The corner-shared FeO<sub>6</sub> octahedra of LiMPO<sub>4</sub> are separated by the oxygen atoms of the PO<sub>4</sub>3- tetrahedra and cannot form a continuous FeO<sub>6</sub> network. Electron conductivity is reduced as a result. On the other hand, a nearly close-packed hexagonal oxygen atom array provides a relatively small free volume for lithium ion motion and therefore, lithium ions in the lattice have small migration speeds at ambient temperate. During charge, lithium ions and corresponding electrons are extracted from the structure, and a new phase of FePO<sub>4</sub> and a new phase interface are formed. During discharge, lithium ions and the corresponding electrons are inserted back into the structure and a new phase of LiMPO<sub>4</sub> is formed outside the FePO<sub>4</sub> phase. Hence, the lithium ions of spherical cathode particles have to go through an inward or an outward structural phase transition, be it extraction or insertion . A critical step of charge and discharge is the formation of the phase interface between LixFePO<sub>4</sub> and Li1-xFePO<sub>4</sub>. As the insertion/extraction of lithium ions proceeds, the surface area of the interface shrinks. When a critical surface area is reached, the electrons and ions of the resulting FePO<sub>4</sub> have low conductivity and two-phase structures are formed. Thus, LiMPO<sub>4</sub> at the center of the particle will not be fully consumed, especially under the condition of large discharge current.
:<chem>LiFe^{II}PO4 <=> Fe^{III}PO4 + Li+ + e-</chem>


Extraction of lithium from {{chem|LiFePO|4}} produces {{chem|FePO|4}} with a similar structure. {{chem|FePO|4}} adopts a P<sub>mnb</sub> space group with a unit cell volume of 272.4&nbsp;Å<sup>3</sup>, only slightly smaller than that of its lithiated precursor. Extraction of lithium ions reduces the lattice volume, as is the case with lithium oxides. {{chem|LiFePO|4}}'s corner-shared {{chem|FeO|6}} octahedra are separated by the oxygen atoms of the {{chem|PO|4|3-}} tetrahedra and cannot form a continuous {{chem|FeO|6}} network, reducing conductivity.
The lithium ions move in the one-dimensional channels in the olivine structures and have high diffusion constants. Besides, the olivine structures experiencing multiple cycles of charge and discharge remain stable and the iron atom still resides in the center of the octahedron. Therefore, putting the limit of electron conductivity aside, LiMPO<sub>4</sub> is a good cathode material with excellent cycling performances.<ref>J. Electrochem. Soc , 1997, 144, 1609-1613.</ref> During a charge, the iron atom in the center of the octahedron has a high spin state.


A nearly close-packed hexagonal array of oxides centers provides relatively little free volume for {{chem|Li|+}} ions to migrate within. For this reason, the ] of {{chem|Li|+}} is relatively low at ambient temperature. The details of the lithiation of {{chem|FePO|4}} and the delithiation of {{chem|LiFePO|4}} have been examined. Two phases of the lithiated material are implicated.<ref name= Love/><ref>Malik, R.; Abdellahi, A.; Ceder, G., "A Critical Review of the Li Insertion Mechanisms in {{chem|LiFePO|4}} Electrodes", J. Electrochem. Soc. 2013, volume 160, pages A3179-A3197. {{doi|10.1149/2.029305jes}}</ref>
==Rapid Development of the LFT Upstream and Downstream Industries==
At present, the root patents of the LFP compounds are held by three professional material companies: Li1-xMFePO<sub>4</sub> by A123, LiMPO<sub>4</sub> by Phostech and LiFePO<sub>4</sub> • zM by Aleees. These patents have been translated to very mature mass production technologies. The largest production capacity is up to 250 tons per month. The key feature of Li1-xMFePO<sub>4</sub> from A123 is the nano-LFP, which converts the originally less conductive LFP into commercial products by modification of its physical properties and addition of noble metals in the anode material, as well as the use of special graphite as the cathodes. The main feature of LiMPO<sub>4</sub> from Phostech is the increased capacitance and conductivity by appropriate carbon coating; the crucial feature of LiFePO<sub>4</sub> • zM from Aleees is the LFP with a high capacitance and low impedance obtained by the stable control of the ferrites and crystal growth. This improved control is realized by applying strong mechanical stirring forces to the precursors in high oversaturation states, which induces crystallization of the metal oxides and LFP.


==Applications==
These breakthroughs and fast development in upstream materials have drawn the attention of lithium battery factories and the automobile industry. It has prompted the developments of batteries and hybrid vehicles. LFP batteries and ordinary lithium batteries are both environmentally benign. The major differences between these two are that the LFP batteries do not have such safety concerns as overheating and explosion, have 4 to 5 times longer cycle lifetimes than the lithium batteries, have 8 to 10 times higher discharge power than the lithium batteries (which can produce an instant high current), and have, under the same energy density, 30 to 50 % less weight than the lithium batteries. The development of the LFP battery is highly valued by corporations such as the Department of Defense of the United States (for their hybrid tanks and Hummers), General Motors, Ford Motor, Toyota Motor, etc.
{{see also|lithium iron phosphate battery}}
LFP cells have an operating voltage of 3.3&nbsp;V, ] of 170 mAh/g, high ], long cycle life and stability at high temperatures.<ref name="SciData8(2024)165">{{cite journal |last1=Chung |first1=Hsien-Ching |title=Charge and discharge profiles of repurposed LiFePO4 batteries based on the UL 1974 standard |journal=Scientific Data |date=2021-07-02 |volume=8 |issue=1 |page=165 |doi=10.1038/s41597-021-00954-3|pmid=34215731 |pmc=8253776 }}</ref>


LFP's major commercial advantages are that it poses few safety concerns such as overheating and explosion, as well as long cycle lifetimes, high power density and has a wider operating temperature range. Power plants and automobiles use LFP.<ref>, Nov 15, 2015, retrieved April 1, 2020</ref><ref>{{Cite web|url=https://offgridham.com/2016/03/about-lifepo4-batteries/|title=What You Need To Know About LiFePO4 Batteries.|first=Chris|last=Warren|date=March 12, 2016}}</ref>
==Properties of LFP and Development of the Industry==
That being said, the market of hybrid vehicles is the determinant. It is the stable and safe olivine structure of LFP material that makes LFP favorable in lithium batteries. Different from other cathode material like Li-Co of layered structures and Li-Mn of spinel structures, LFP of olivine structures has strong oxygen covalent bonds and does not explode upon the short-circuit of lithium batteries. This feature might not be the most important for other mobile IT products but it is for lithium batteries installed on vehicles.


BAE has announced that their HybriDrive Orion 7 hybrid bus uses about 180&nbsp;kW LFP battery cells. ] has developed multi-trillion watt battery systems that are capable of subsidiary services of the power network, including spare capacity and frequency adjustment. In China, BAK and Tianjin Lishen are active in the area.
According to US AABC’s statistics, one out of 70,000 hybrid vehicles (PHEV, HEV, BEV) using batteries containing cobalt or manganese will explode if they have the same incidence rate as the lithium batteries of notebooks and cell phones. This number is beyond the wildest estimation of automakers. What they give top priority is safety rather than capacity. The reason is simple: It is too expensive to recall automobiles, tens of thousands of times more expensive than recalling notebooks. Therefore, safety has to be weighed against battery life.


The safety is a crucial property for certain applications. For example, in 2016 an LFP-based energy storage system was installed in ] on ] (the highest alpine lodge in ]). As of 2024, the system is still operating safely.{{r|Batteries10(2024)202}}
Although LFP has 25% less capacity than other lithium batteries due to its material structure, it has 70% more performance than nickel-hydrogen battery. LFP’s improved capacity and stability draw automakers’ interests. For them, LFP can meet both the requirements of safety and battery life. Hence, hybrid vehicles are the critical market.


=== Comparison ===
According to statistics, HEV, PHEV, and BEV would have, in 2008, a market of at least 7 hundred million US dollars worldwide, and at least 5 billion US dollars by 2012. From 2008 to 2015, the sales of hybrid vehicles worldwide will increase by at least 12%. In 2012, the sales of hybrid vehicles in the US will exceed 1 million. Production of hybrid vehicles in Japan will increase 6.6% from 2008 to 2011. Over all, the market for hybrid vehicle batteries for will expand 10.4% from 2010 to 2015 and the markets of hybrid vehicle parts will increase 17.4%.
Although LFP has 25% less specific energy (Wh/g) than lithium batteries with ] (e.g. nickel-cobalt-manganese, NCM) cathode materials, primarily due to its operational voltage (3.2 volts vs 3.7 for NCM-type cathode chemistries), it has 70% more than ].


The major differences between LFP batteries and other lithium-ion battery types is that LFP batteries contain no ] (removing ethical and economic questions about cobalt's availability) and have a flat discharge curve.
In addition to compact vehicles, bus makers will also try to incorporate LFP batteries into their products. BAE has announced that their HybriDrive Orion 7 hybrid bus will use about 180KW LFP battery cells. Power plants are also using LFP now. AES in the US has developed multi-trillion watt battery systems that are capable of subsidiary services of the power network, including spare capacity and frequency adjustment.


LFP batteries have drawbacks, originating from a high electronic ] of LFP, as well as the lower maximum charge/discharge voltage. The ] is significantly lower than {{chem|LiCoO|2}} (although higher than the ]).
A major competitor to LiFePO<sub>4</sub> is lithium manganese spinel, which GM has chosen to use for the ], a gas-electric hybrid vehicle.
Before this new generation of materials can be used as the power source for electric bicycles, gas-electric hybrid vehicles and automation vehicles there lies one large obstacle: patents. Many of the companies that entered the field in the early stages have already received patents, which may result in other companies entering the market at a later time running into legal trouble.


Lithium cobalt oxide based battery chemistries are more prone to thermal runaway if overcharged and cobalt is both expensive and not widely geographically available. Other chemistries such as nickel-manganese-cobalt (NMC) have supplanted LiCo chemistry cells in most applications. The original ratio of Ni to Mn to Co was 3:3:3, whereas today, cells are being made with ratios of 8:1:1 or 6:2:2, whereby the Co content has been drastically reduced.
At present, the root patents of the LFP compounds are held by the three professional material companies: Li1-xMFePO<sub>4</sub> by A123, LiMPO<sub>4</sub> by Phostech and LiFePO<sub>4</sub> • zM by Aleees. And these patents have been developed into very mature mass production technologies. The largest production capacity is up to 250 tons per month. The key feature of Li1-xMFePO<sub>4</sub> of A123 is the nano-LFP, which converts the originally less conductive LFP into commercial products by modification of its physical properties and addition of noble metal in the anode material, as well as the use of special graphite as the cathodes. The main feature of LiMPO<sub>4</sub> of Phostech is the increased capacitance and conductivity by appropriate carbon coating; the crucial feature of LiFePO<sub>4</sub> • zM of Aleees is the LFP with the high capacitance and low impedance obtained by the stable control of the ferrites and the crystal growth. This improved control is realized by applying strong mechanical stirring forces to the precursors in high oversaturation states, which induces crystallization of the metal oxides and LFP.


LiFePO<sub>4</sub> batteries are comparable to ] and are often being touted as a drop-in replacement for lead acid applications. The most notable difference between lithium iron phosphate and lead acid is the fact that the lithium battery capacity shows only a small dependence on the discharge rate. With very high discharge rates, for instance 0.8C, the capacity of the lead acid battery is only 60% of the rated capacity. Therefore, in cyclic applications where the discharge rate is often greater than 0.1C, a lower rated lithium battery will often have a higher actual capacity than the comparable lead acid battery. This means that at the same capacity rating, the lithium will cost more, but a lower capacity lithium battery can be used for the same application at a lower price. The cost of ownership when considering the lifecycle further increases the value of the lithium battery when compared to a lead acid battery.<ref>{{Cite web|title = Lead Acid Vs LiFePO4 Batteries|url = https://www.power-sonic.com/blog/lithium-vs-lead-acid-batteries/|website = Power Sonic - Trusted Battery Solutions|date = 25 February 2020}}</ref>{{Third-party inline|date=September 2024|reason=A LiFePO4 battery manufacturer probably isn't a good reference for their advantages over SLA}}, but they have much poorer performance at lower temperatures, as covered in the section on ].
These breakthroughs and fast development in upper source materials, has drawn the attention of lithium battery factories and the automobile industry. It has led some to surmise that this technology when applied to lithium batteries and gas-electric hybrid vehicles will give lead to a bright future for hybrid vehicles. LFP batteries and ordinary lithium batteries are both environmentally friendly. The major differences between these two are that the LPF batteries do not have such safety concerns as overheating and explosion, that the LPF batteries have 4 to 5 times longer cycle lifetimes than the lithium batteries, that the LPF batteries have 8 to 10 times higher discharge power than the lithium batteries (which can produce an instant high current), and that the LFP batteries have, under the same energy density, 30 to 50 % less weight than the lithium batteries. The development of LFP battery is highly valued in the industry, and has been developed for the United States Department of Defense's gas-electric hybrid tanks and Hummers, General Motors, Ford Motor, Toyota Motor and so on.


==Intellectual property==
From a development point of view, the U.S. auto industry estimates that by 2010, there will be over four million gas-electric hybrid vehicles on American roads. General Motors of the United States has decided to work towards the "large-scale production of electric cars" to break the domination of Japanese manufacturers. As U.S. consumers are under the extremely high pressure of skyrocketing oil prices, General Motors believe that the future auto market must be able to use all kinds of energy, and the electric car will be the key to success. Therefore, at the 2007 North American International Auto Show, GM unveiled the Plug-in Hybrid Electric Vehicle(PHEV) concept car "Chevrolet Volt Concept" and with the development of new GM hybrid system ( E-FLEX), one ordinary household power supply can be connected to the car for charging the lithium iron phosphate battery. When the Volt Concept reaches mass production, each car will able to reduce 500 gallons (1,900 liters) of gasoline consumption each year, and will reduce carbon dioxide output by 4400&nbsp;kg.
{{More citations needed|section|small=y|find=LiFePO4 patent lawsuits|date=September 2024}}
There are 4 groups of patents on LFP battery materials:


# The ] (UT) patented the materials with the crystalline structure of LiFePo4 and their use in batteries.
Facing such strong and unstoppable development, some industrial banks, venture capital funds and investment companies, have focused on the overall arrangement on the upper source material companies. In addition to the above-mentioned three companies, besides A123 in the United States, ActaCell Inc. just received 5,800,000 U.S. dollars funding from Google.org, Applied Materials (AMAT) Venture Capital and other venture capital firms. ActaCell’s main focus is to carry out the study outcome of University of Texas to the market. Professor Arumugam Manthiram has done a long-term study of development of spinel-based structure and superconducting materials. He served as a research assistant at UT, and then was promoted to professor. In recent years he discovered that when adding the expensive conductive polymers in the lithium iron phosphate (LFP), the grams capacity 166Ah/g of lithium iron phosphate (LFP) can be made in the laboratory, and then applied the microwave method to speed up the ceramic powder process of lithium iron phosphate (LFP). As to whether or not to circumvent the lithium iron phosphate (LFP) patents of A123, Aleees and Phostech by adding the conducting polymer, it is unclear at this current stage.
# ], ] and the ] (CNRS) own patents, that claim improvements of the original LiFePo4 by carbon coating that enhance its conductivity.<ref>{{Cite web|url=https://www.clariant.com/pt/Corporate|title=Especialidades químicas da Clariant|first=Clariant Ltd|last=Basel|website=Clariant Ltd.}}</ref>
# The key feature of {{chem|Li|1−''x''|MFePO|4}} from ] is the nano-LFP, which modifies its physical properties and adds noble metals in the anode, as well as the use of special graphite as the cathode.
# The main feature of {{chem|LiMPO|4}} from Phostech is increased capacitance and conductivity by an appropriate carbon coating. The special feature of {{chem|LiFePO|4}} • zM from Aleees a high capacitance and low impedance obtained by the stable control of the ferrites and crystal growth. This improved control is realized by applying strong mechanical stirring forces to the precursors in high oversaturation states, which induces crystallization of the metal oxides and LFP.


These patents underlie mature mass production technologies. The largest production capacity is up to 250 tons per month.
However, the pace of the lower source industry is not slowing down at all, in Europe, BOSCH committed to the public by continuously expanding the automation and electric powered vehicle development in 2008. Some people in Europe believe the applications of the technologies are very limited. The traditional reciprocating engine may still have an advantage of 20 years, but eventually the vehicle electric vehicles will be able to catch up.


In patent lawsuits in the US in 2005 and 2006, UT and Hydro-Québec claimed that {{chem|LiFePO|4}} as the cathode infringed their patents, {{patent|US|5910382}} and {{patent|US|6514640}}. The patent claims involved a unique crystal structure and a chemical formula of the battery cathode material.
BOSCH has a proud history of automotive technology research and development, and their own R&D department, which as a result of not looking to purchase technology from other corporations has been busy developing its own anti-lock brake and TCS tracking control system. They will be redesigned with a gas-electric hybrid computer program and will be featured in the VW Touareg and the PORSCHE Cayenne hybrid from BOSCH which will be on the market in 2010.


On April 7, 2006, A123 filed an action seeking a declaration of non-infringement and invalidity UT's patents. A123 separately filed two ] Reexamination Proceedings before the ] (USPTO), in which they sought to invalidate the patents based upon prior art.
BOSCH was one of the first companies that decided to focus and maintain a leading edge in fuel technology. Finally, others in the industry are beginning to wake up as the automotive safety becomes concerned about safety and now that alternative forms of energy are beginning to try to catch up. BOSCH believes they need to deeply explore the field of electric power, as it is going to be widespread technology worldwide.


In a parallel court proceeding, UT sued ], a company that commercializes LFP products that alleged infringement.
BOSCH and South Korea SAMSUNG are cooperating to develop lithium batteries and carry out mass production at a cost of about 4,000,000 U.S. dollars.<ref>http://www.reuters.com/article/scienceNews/idUSSEO3739020080616</ref> Although it is predicted that it will take about four to five years to move into the matured stage, BOSCH in any case will continue to invest in this effort in order to maintain its position as the top leader in the automobile technology.


The USPTO issued a Reexamination Certificate for the '382 patent on April 15, 2008, and for the '640 patent on May 12, 2009, by which the claims of these patents were amended. This allowed the current patent infringement suits filed by Hydro-Quebec against Valence and A123 to proceed. After a Markman hearing, on April 27, 2011, the Western ] held that the claims of the reexamined patents had a narrower scope than as originally granted. The key question was whether the earlier ]'s patents from the UT (licensed to Hydro-Quebec) were infringed by A123, that had its own improved versions of LiFePO4 patents, that contained ] dopant. The end results was licensing of Goodenough's patents by A123 under undisclosed terms.<ref>{{cite journal |last1=Taylor |first1=E. Jennings |last2=Inman |first2=Maria |title=Looking at Patent Law: Patenting a Unitized Regenerative Fuel Cell System for Space Energy Storage Applications--A Case Study |journal=The Electrochemical Society Interface |date=1 March 2020 |volume=29 |issue=1 |pages=37–42 |url=https://iopscience.iop.org/article/10.1149/2.F04201IF/pdf |doi=10.1149/2.F04201IF|doi-access=free }}</ref>
Another European automotive components assembler Continental, announced that their lithium iron phosphate (LFP) partners are A123 Systems and Johnson Controls-Saft. Continental will supply the batteries for Mercedes Benz. For dealings with Bosch, they may consider doing it themselves or purchasing from A123. For the security of the supply chain, they bought stocks from a small battery factory Enax in Japan, but the company is only capable of producing small voltage products.


On December 9, 2008, the ] revoked Dr. Goodenough’s patent numbered 0904607. This decision basically reduced the patent risk of using LFP in European automobile applications. The decision is believed to be based on the lack of novelty.<ref>{{Cite web | url=http://www.greencarcongress.com/2008/12/epo-revokes-uni.html | title=EPO Revokes Univ. Of Texas European Patent on Lithium Metal Phosphates; Boon for Valence}}</ref>
GS YUASA in Japan is a rising company that has announced the result of their work on the application of the anode of large-scale battery unit with its independently developed carbon-load of lithium iron phosphate (LFP). The tests results for external size of 115mm × 47mm × 170mm square shaped "LIM40" industrial battery unit indicated that even with the 400A large current discharge, the capacity is nearly not reduced. The original products without using the carbon load, had a 400A discharge unit that actually only had half the capacity of a 40A discharge. In addition, the trial product was usable in temperatures as low temperature as -20℃.


The first major settlement was the lawsuit between ] and the UT. In October 2008,<ref>{{Cite web | url=http://techon.nikkeibp.co.jp/english/NEWS_EN/20081007/159256/ |title = NTT Settles Lawsuit over Li-ion Battery Patents}}</ref> NTT announced that they would settle the case in the Japan Supreme Civil Court for $30 million. As part of the agreement, UT agreed that NTT did not steal the information and that NTT would share its LFP patents with UT. NTT’s patent is also for an olivine LFP, with the general chemical formula of {{chem|A|''y''|MPO|4}} (A is for alkali metal and M for the combination of Co and Fe), now used by ]. Although chemically the materials are nearly the same, from the viewpoint of patents, {{chem|A|''y''|MPO|4}} of NTT is different from the materials covered by UT. {{chem|A|''y''|MPO|4}} has higher capacity than {{chem|LiMPO|4}}. At the heart of the case was that NTT engineer Okada Shigeto, who had worked in the UT labs developing the material, was accused of stealing UT’s ].
In China, the two heavy-weight lithium battery manufacturers: BAK and Tianjin Lishen, also announced their building plans of the special LFP factories, which will have annual outputs of 20,000,000 lithium iron phosphate (LFP) batteries, will be completed at the end of 2008 and early 2009 respectively. The total amount of investment in their construction is 600million dollars. As for the upper source cooperative companies, they have yet to be found in the newspaper; the speculation is that they will be cooperating with one of the three lithium iron phosphate (LFP) vendors which has a production factory in Asia.


As of 2020, an organization named claims to own the key IP and offers licenses. It is a consortium between Johnson Matthey, the CNRS, University of Montreal, and Hydro Quebec.
As a result, by 2010, the competition landscape of lithium iron phosphate (LFP) industry in Europe, Asia and the United States, seems to have been decided more or less. With the high safety and stability of lithium iron phosphate(LFP) materials, the level of technology from each factory seems to be less important. The only decisive factor is the market price. According to general estimates, the union of lithium iron phosphate (LFP) will be able to lower battery price to 0.35 U.S. dollars per watt hours by 2010, will be able to take the lead in the rapid development of gas-electric hybrid vehicles and lithium battery bicycles, coming out as the ultimate winner.


==LFP Patent Wars== ==Research==
Professor Goodenough at UT Austin, who discovered LFP of olivine structures more than ten years ago, probably would not expect that a micro material made of lithium iron phosphate (commonly used in fertilizers) could have such huge development and rapidly revolutionize many important industries. This prosperous development also elicits patent problems.


=== Power density ===
In the patent lawsuits in the US in 2005 and 2006, UT and ] claimed that every battery using LiFePO<sub>4</sub> as the cathode and the cathode material used in some lithium ion batteries infringed their patents, US patent No 5910382 and 6514640. The ‘382 and ‘640 patents claimed a special crystal structure and a chemical formula of the battery cathode material.
LFP has two shortcomings: low conductivity (high overpotential) and low lithium diffusion constant, both of which limit the charge/discharge rate. Adding conducting particles in delithiated {{chem|FePO|4}} raises its electron conductivity. For example, adding conducting particles with good diffusion capability like graphite and carbon<ref name="Cramer-2004">{{cite journal |last1=Deb |first1=Aniruddha |last2=Bergmann |first2=Uwe |last3=Cairns |first3=Elton J. |last4=Cramer |first4=Stephen P. |title=Structural Investigations of LiFePO 4 Electrodes by Fe X-ray Absorption Spectroscopy |journal=The Journal of Physical Chemistry B |date=June 2004 |volume=108 |issue=22 |pages=7046–7051 |doi=10.1021/jp036361t}}</ref> to {{chem|LiMPO|4}} powders significantly improves conductivity between particles, increases the efficiency of {{chem|LiMPO|4}} and raises its reversible capacity up to 95% of the theoretical values. However, addition of conductive additives also increases the "dead mass" present in the cell that does not contribute to energy storage. {{chem|LiMPO|4}} shows good cycling performance even under charge/discharge current as large as 5C.<ref name="Wokaun-2005">{{cite journal |last1=Haas |first1=O. |last2=Deb |first2=A. |last3=Cairns |first3=E. J. |last4=Wokaun |first4=A. |title=Synchrotron X-Ray Absorption Study of LiFePO Electrodes |journal=Journal of the Electrochemical Society |date=2005 |volume=152 |issue=1 |pages=A191 |doi=10.1149/1.1833316}}</ref>


=== Stability ===
On April 7, 2006, in the district court of Massachusetts, the USA ruled, as a declarative precedent, that those LFP olivine materials with different crystal structures and chemical formulae did not infringe the ‘382 and ‘640 patents. The ruling and other relevant rulings forced UT Austin to revise the scope of the ‘382 patent and narrow its claims. Those companies owning LFP of different crystal structures went even further. On April 15, 2008, the USPTO issued reviews of the revised claim and two new claims.
Coating LFP with inorganic oxides can make LFP’s structure more stable and increase conductivity. Traditional {{chem|LiCoO|2}} with oxide coating shows improved cycling performance. This coating also inhibits dissolution of Co and slows the decay of {{chem|LiCoO|2}} capacity. Similarly, {{chem|LiMPO|4}} with an inorganic coating such as ]<ref name="Lee-2004">{{cite journal |last1=Kwon |first1=Sang Jun |last2=Kim |first2=Cheol Woo |last3=Jeong |first3=Woon Tae |last4=Lee |first4=Kyung Sub |title=Synthesis and electrochemical properties of olivine LiFePO4 as a cathode material prepared by mechanical alloying |journal=Journal of Power Sources |date=October 2004 |volume=137 |issue=1 |pages=93–99 |doi=10.1016/j.jpowsour.2004.05.048|bibcode=2004JPS...137...93K }}</ref> and ],<ref name="Jamnik-2006">{{cite journal |last1=Dominko |first1=R. |last2=Bele |first2=M. |last3=Gaberscek |first3=M. |last4=Remskar |first4=M. |last5=Hanzel |first5=D. |last6=Goupil |first6=J.M. |last7=Pejovnik |first7=S. |last8=Jamnik |first8=J. |title=Porous olivine composites synthesized by sol–gel technique |journal=Journal of Power Sources |date=February 2006 |volume=153 |issue=2 |pages=274–280 |doi=10.1016/j.jpowsour.2005.05.033|bibcode=2006JPS...153..274D }}</ref> has a better cycling lifetime, larger capacity and better characteristics under rapid discharge. The addition of a conductive carbon increases efficiency. ] Zosen and Aleees reported that addition of conducting metal particles such as copper and silver increased efficiency.<ref name="Tessier-2008">{{cite journal |last1=León |first1=B. |last2=Vicente |first2=C. Pérez |last3=Tirado |first3=J. L. |last4=Biensan |first4=Ph. |last5=Tessier |first5=C. |title=Optimized Chemical Stability and Electrochemical Performance of LiFePO Composite Materials Obtained by ZnO Coating |journal=Journal of the Electrochemical Society |date=2008 |volume=155 |issue=3 |pages=A211–A216 |doi=10.1149/1.2828039}}</ref> {{chem|LiMPO|4}} with 1 wt% of metal additives has a reversible capacity up to 140 mAh/g and better efficiency under high discharge current.


===Metal substitution===
On Dec 9th, 2008, European Patent Office revokes Dr. Goodenough’s LiMPO<sub>4</sub> patent, patent number 0904607. This decision basically reduces the patent risk of using lithium iron phosphate in automobile application at Europe. The reason of this decision is believed to be based on the lack of novelty. While UT can still appeal the EPO decision, this result encourages the electric vehicle makers to pursue on lithium iron phosphate battery technologies in Europe.<ref>http://www.greencarcongress.com/2008/12/epo-revokes-uni.html</ref>
Substituting other materials for the iron or lithium in {{chem|LiMPO|4}} can also raise efficiency. Substituting zinc for iron increases crystallinity of {{chem|LiMPO|4}} because zinc and iron have similar ionic radii.<ref name="Liu-2008">{{cite journal |last1=Liu |first1=H. |last2=Wang |first2=G.X. |last3=Wexler |first3=D. |last4=Wang |first4=J.Z. |last5=Liu |first5=H.K. |title=Electrochemical performance of LiFePO4 cathode material coated with ZrO2 nanolayer |journal=Electrochemistry Communications |date=January 2008 |volume=10 |issue=1 |pages=165–169 |doi=10.1016/j.elecom.2007.11.016}}</ref> ] confirms that {{chem|LiFe|1−''x''|M|''x''|PO|4}}, after metal substitution, has higher reversibility of lithium ion insertion and extraction. During lithium extraction, Fe (II) is oxidized to Fe (III) and the lattice volume shrinks. The shrinking volume changes lithium’s returning paths.


===Synthesis processes===
On May 12, 2009, the USPTO published the re-examination certification for patent '640, concluding that the claims of the patent, with some amendments, are patentable. This allows the current patent infringement suits filed by Hydro-Quebec against ] and A123Systems to proceed.
Mass production with stability and high quality still faces many challenges.
<ref>http://bioage.typepad.com/files/US-6514640C1.pdf</ref>


Similar to lithium oxides, {{chem|LiMPO|4}} may be synthesized by a variety of methods, including: ], emulsion drying, ], solution coprecipitation, ], electrochemical synthesis, ] irradiation, ] process{{vague|date=March 2019}}, hydrothermal synthesis, ultrasonic ] and ].
While the patent war of LFP formulae and crystal structures is still going, it has involved many famous manufacturers of lithium batteries, such as Panasonic, ASEC (an energy supply subsidiary of Renault Samsung Motors), Johnson Controls-SAFT, Toshiba, Hitachi, Aleees, Enerdel, Altairnano, Mitsui Zosen, LG, Johnson controls, AESC, Valence, SAFT, ABB, E-one Moli. They are all trying to win this LFP patent war. The US government, too, has invested 55 million US dollars in LFP development.


In the emulsion drying process, the emulsifier is first mixed with kerosene. Next, the solutions of lithium salts and iron salts are added to this mixture. This process produces nanocarbon particles.<ref name="Scrosati-2002">{{cite journal |last1=Croce |first1=F. |last2=D' Epifanio |first2=A. |last3=Hassoun |first3=J. |last4=Deptula |first4=A. |last5=Olczac |first5=T. |last6=Scrosati |first6=B. |title=A Novel Concept for the Synthesis of an Improved LiFePO Lithium Battery Cathode |journal=Electrochemical and Solid-State Letters |date=2002 |volume=5 |issue=3 |pages=A47–A50 |doi=10.1149/1.1449302|doi-access=free }}</ref> Hydrothermal synthesis produces {{chem|LiMPO|4}} with good crystallinity. Conductive carbon is obtained by adding ] to the solution followed by thermal processing.<ref name="Zhang-2005">{{cite journal |last1=Ni |first1=J.F. |last2=Zhou |first2=H.H. |last3=Chen |first3=J.T. |last4=Zhang |first4=X.X. |title=LiFePO4 doped with ions prepared by co-precipitation method |journal=Materials Letters |date=August 2005 |volume=59 |issue=18 |pages=2361–2365 |doi=10.1016/j.matlet.2005.02.080}}</ref> Vapor phase deposition produces a thin film {{chem|LiMPO|4}}.<ref name="Chung-2004">{{cite journal |last1=Cho |first1=Tae-Hyung |last2=Chung |first2=Hoon-Taek |title=Synthesis of olivine-type LiFePO4 by emulsion-drying method |journal=Journal of Power Sources |date=June 2004 |volume=133 |issue=2 |pages=272–276 |doi=10.1016/j.jpowsour.2004.02.015|bibcode=2004JPS...133..272C }}</ref> In flame spray pyrolysis FePO<sub>4</sub> is mixed with ] and ] and charged with ]. The mixture is then injected inside a flame and filtered to collect the synthesized {{chem|LiFePO|4}}.<ref name="Wiggers-2012">{{cite journal |last1=Hamid |first1=N.A. |last2=Wennig |first2=S. |last3=Hardt |first3=S. |last4=Heinzel |first4=A. |last5=Schulz |first5=C. |last6=Wiggers |first6=H. |title=High-capacity cathodes for lithium-ion batteries from nanostructured LiFePO4 synthesized by highly-flexible and scalable flame spray pyrolysis |journal=Journal of Power Sources |date=October 2012 |volume=216 |pages=76–83 |doi=10.1016/j.jpowsour.2012.05.047|bibcode=2012JPS...216...76H }}</ref>
==LFP Lawsuit Settlement: NTT Paid 30 Million US Dollars to UT==
Because this novel material could make an important energy storage contribution to PHEV, HEV, and BEVs, significant interest has developed in its patent history. The first challenge of commercial products is patent infringement. Many of the pioneering companies in this field have exhaustive and thorough patent maps of various olivine formulations and preparations. Follow on patents often fall within these patent maps. The first major case of an expensive settlement is the lawsuit between NTT Japan and the University of Texas-Austin (UT). In October 2008,<ref>http://techon.nikkeibp.co.jp/english/NEWS_EN/20081007/159256/</ref> NTT announced that they would settle the case in the Japan Supreme Civil Court with UT by paying to UT 30 million US dollars. As part of the agreement UT agreed that NTT did not steal the information and NTT will share its NTT’s patents of LFP materials with UT. NTT’s patent is also for an olivine LiFePO4 (LFP), with the general chemical formula of AyMPO<sub>4</sub> (A is for alkali metal and M for the combination of Co and Fe.). This compound is what BYD is using now. (BYD gained substantial media exposure after Warren Buffet’s announcement of investing in BYD’s LFP hybrid vehicle project.) Although chemically the materials are nearly the same, from the viewpoint of patents, AyMPO<sub>4</sub> of NTT is different from the initial LiMPO<sub>4</sub> materials covered by the UT. A main difference is that the AyMPO<sub>4</sub> has higher capacity than LiMPO<sub>4</sub>, although since the patents were matter of composition based, the differences in performance were not totally germane. At the heart of the case was that NTT engineer - Okada Shigeto - who worked in the labs at UT developing the material - was suspected of stealing UT’s business secrets and used them when he returned to Japan.


==Improvement of LFP== ===Effects of temperature===
The effects of temperature on lithium iron phosphate batteries can be divided into the effects of high temperature and low temperature.
Today, the major flaws of LFP that slow down LFP applications are low conductivity and low lithium diffusion constant. Researchers all over the world are working on improving the conductivity of LiMPO<sub>4</sub>. A123 is working around the problem of LFP’s extremely low conductivity (10-10 ~ 10-9 S/cm) by coating and replacing the material and converting the material into nano particles. Adding conducting particles in delithiated FePO<sub>4</sub> raises its electron conductivity. For example, adding conducting particles with good diffusion capability like graphite and carbon <ref>J. Phys. Chem. B 2004, 108, 7046-7051.</ref> to LiMPO<sub>4</sub> powders significantly improves conductivity between particles, increases the efficiency of LiMPO<sub>4</sub> and raises its reversible capacity up to 95% of the theoretical values. LiMPO<sub>4</sub> shows good cycling performance even under the condition of as large charge/discharge current as 5C.<ref>J. Electrochem. Soc, 2005, 152, A191-A196.</ref>


Generally, LFP chemistry batteries are less susceptible to thermal runaway reactions like those that occur in lithium cobalt batteries; LFP batteries exhibit better performance at an elevated temperature. Research has shown that at room temperature (23&nbsp;°C), the initial capacity loss approximates 40-50&nbsp;mAh/g. However, at 40&nbsp;°C and 60&nbsp;°C, the capacity losses approximate 25 and 15&nbsp;mAh/g respectively, but these capacity losses were spread over 20 cycles instead of a bulk loss like that in the case of room temperature capacity loss.<ref>{{cite journal |title=Thermal Stability of LiFePO4 -Based Cathodes |journal=Electrochemical and Solid-State Letters |year=2000 |last1=Andersson |first1=Anna S |last2=Thomas |first2=John O |last3=Kalska |first3=Beata |last4=Häggström |first4=Lennart |volume=3 |issue=2 |pages=66–68 |doi=10.1149/1.1390960 |url=https://iopscience.iop.org/article/10.1149/1.1390960 |accessdate=2021-11-18 |url-access=subscription }}</ref>
Besides, coating LFP with inorganic oxides can make LFP’s structure more stable and increase conductivity. Traditional LiCoO<sub>2</sub> with oxide coating shows improved cycling performance. This coating also inhibits dissolution of Co and slows the decay of LiCoO<sub>2</sub> capacity. Similarly, LiMPO<sub>4</sub> with inorganic coating, such as ZnO<ref>J. Power Sources, 2004, 137, 93–99.</ref> and ZrO<sub>2</sub>,<ref>J. Power Sources, 2006, 153, 274–280.</ref> has a better cycling lifetime, larger capacity and better characteristics under the condition of a large discharge current. The addition of a conductive carbon in LiMPO<sub>4</sub> increases the efficiency of LiMPO<sub>4</sub>, too. Mitsui Zosen Japan and Aleees reported that addition of other conducting metal particles, such as copper and silver, also increased LiMPO<sub>4</sub>’s efficiency.<ref>J. Electrochem. Soc, 2008, 155, A211-A216.</ref> LiMPO<sub>4</sub> with 1 wt. % of metal additives has a reversible capacity up to 140mAh/g and better characteristics under the condition of large discharge current.


However, this is only true for a short cycling timeframe. Later yearlong study has shown that despite LFP batteries having double the equivalent full cycle, the capacity fade rate increased with increasing temperature for LFP cells but the increasing temperature does not impact NCA cells or have a negligible impact on the aging of NMC cells.<ref>{{cite journal |title=Degradation of Commercial Lithium-Ion Cells as a Function of Chemistry and Cycling Conditions |journal=Journal of the Electrochemical Society |year=2020 |last1=Preger |first1=Yulia |last2=Barkholtz |first2=Heather M. |last3=Fresquez |first3=Armado |last4=Campbell |first4=Danel L. |last5=Juba |first5=Benjamin W. |volume=167 |issue=12 |page=120532 |doi=10.1149/1945-7111/abae37 |bibcode=2020JElS..167l0532P |s2cid=225506214 |doi-access=free |osti=1650174 |url=https://www.osti.gov/biblio/1650174 }}</ref> This capacity fade is primarily due to the ] (SEI) formation reaction being accelerated by increasing temperature.
==Metal Substitution==
Substituting other metals for the iron or lithium in LiMPO<sub>4</sub> can also raise its efficiency. A123 and Valence reported the substitution of magnesium, titanium, manganese, zirconium and zinc. Take zinc substitution for example. Substituting zinc for iron increases crystallinity of LiMPO<sub>4</sub> because zinc and iron have similar ion radii.<ref>Electrochem Commun, 2008, 10, 165–169.</ref> Cyclic voltammetry also confirms that LiFe1-xMxPO<sub>4</sub>, after metal substitution, has higher reversibility of lithium ion insertion and extraction. During lithium extraction, Fe (II) is oxidized to Fe (III) and the lattice volume shrinks. The shrinking volume changes lithium’s returning paths.


LFP batteries are especially affected by decreasing temperature which possibly hamper their application in high-latitude areas. The initial discharge capacities for LFP/C samples at temperatures of 23, 0, -10, and -20&nbsp;°C are 141.8, 92.7, 57.9 and 46.7&nbsp;mAh/g with ] 91.2%, 74.5%, 63.6% and 61.3%. These losses are accounted for by the slow diffusion of lithium ions within electrodes and the formation of SEI that come with lower temperatures which subsequently increase the charge-transfer resistance on the electrolyte-electrode interfaces.<ref>{{cite journal |title=A comparative study on the low-temperature performance of LiFePO4/C and Li3V2(PO4)3/C cathodes for lithium-ion batteries |journal=Journal of Power Sources |date=February 2011 |last1=Rui |first1=X.H. |last2=Jin |first2=Y. |last3=Feng |first3=X.Y. |last4=Zhang |first4=L.C. |last5=Chen |first5=C.H. |volume=196 |issue=4 |pages=2109–2114 |issn=0378-7753 |doi=10.1016/j.jpowsour.2010.10.063 |url=https://linkinghub.elsevier.com/retrieve/pii/S037877531001863X |accessdate=2021-11-18 |url-access=subscription }}</ref> Another possible cause of the lowered capacity formation is lithium plating. As mentioned above, low temperature lowers the diffusion rate of lithium ions within the electrodes, allowing for the lithium plating rate to compete with that of intercalation rate. The colder condition leads to higher growth rates and shifts the initial point to lower state of charge which means that the plating process starts earlier.<ref>{{cite journal |title=Nondestructive detection, characterization, and quantification of lithium plating in commercial lithium-ion batteries |journal=Journal of Power Sources |date=May 2014 |last1=Petzl |first1=Mathias |last2=Danzer |first2=Michael A. |volume=254 |pages=80–87 |issn=0378-7753 |doi=10.1016/j.jpowsour.2013.12.060 |bibcode=2014JPS...254...80P |url=https://linkinghub.elsevier.com/retrieve/pii/S0378775313020387 |accessdate=2021-11-18 |url-access=subscription }}</ref> Lithium plating uses up lithium which then compete with the intercalation of lithium into graphite, decreasing the capacity of the batteries. The aggregated lithium ions are deposited on the surface of electrodes in the form of “plates” or even dendrites which may penetrate the separators, short-circuiting the battery completely.<ref>{{cite journal |title=Thermal issues about Li-ion batteries and recent progress in battery thermal management systems: A review |journal=Energy Conversion and Management |date=October 2017 |last1=Liu |first1=Huaqiang |last2=Wei |first2=Zhongbao |last3=He |first3=Weidong |last4=Zhao |first4=Jiyun |volume=150 |pages=304–330 |issn=0196-8904 |doi=10.1016/j.enconman.2017.08.016 |bibcode=2017ECM...150..304L |url=https://linkinghub.elsevier.com/retrieve/pii/S0196890417307288 |accessdate=2021-11-18 |url-access=subscription }}</ref>
==Improvement of LFP Synthesis Processes==
Similar to lithium oxides, LiMPO<sub>4</sub> may be synthesized by the following methods: 1. solid-phase synthesis, 2. emulsion drying, 3. sol-gel process 4. solution coprecipitation, 5. vapor phase deposition, 6. electrochemical synthesis, 7. electron beam irradiation, 8. microwave process 9. hydrothermal synthesis, 10. ultrasonic pyrolysis, 11. spray pyrolysis, etc. Different processes have different results. For example, in the emulsion drying process, the emulsifier is first mixed with kerosene. Next, the solutions of lithium salts and iron salts are added to this mixture. This process produces carbon particles of nano sizes.<ref>Electrochem and Solid-State Lett, 2002, 5, A47-A50.</ref> Hydrothermal synthesis produces LiMPO<sub>4</sub> with good crystallinity. Conductive carbon is obtained by adding ] to the solution followed by thermal processing.<ref>Materials Letters, 2005, 59, 2361–2365.</ref> Vapor phase deposition produces a thin film LiMPO<sub>4</sub>.<ref>J. Power Sources, 2004, 133, 272–276.</ref>

LFP batteries also have their drawbacks. There are ongoing international patent suits regarding this technology, and mass production with stable and high quality still faces many challenges. The current low production levels mean that LFP batteries tend to cost more than their LiCoO<sub>2</sub> equivalents. The ] of LFP batteries is significantly lower than LiCoO<sub>2</sub> (although well higher than its main competitor for safety and lifespan, the ]), and the market acceptance for large batteries is rather low in certain applications, making LFP batteries harder to commercialize.

==Example application==

]
] pushed for cleaner air ahead of the ] by ordering electric buses for transport at the games and in the city of ]. The technology chosen was originally hydrogen battery ]s but was changed to LiFePO<sub>4</sub> in order to meet critical path milestones of the contract, and costs. The system battery voltage has been set at 360 V] with a variety of energy capacities depending on the route of the particular bus. Ranges are expected to be 150 to 300 kilometers per charge. Lithium powered buses offer a solution to the growing air pollution in the cities in and around the more developed China harbor area, and the ].

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==See also== ==See also==
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==References==
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{{lithium compounds}}
{{iron compounds}}
{{Phosphates}}


{{DEFAULTSORT:Lithium Iron Phosphate}} {{DEFAULTSORT:Lithium Iron Phosphate}}
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