View source for Lithium-ion battery

{{Batteries
|image=[[Image:Lithium-Ionen-Accumulator.jpg|200px]]
|caption=Lithium-ion battery of Varta, [[Museum Autovision]], [[Altlußheim]], [[Deutschland]]
|EtoW=160 [[Watt hour|Wh]]/[[kg]]
|EtoS=270 [[Watt hour|Wh]]/[[Liter|l]]
|PtoW=1800 [[Watt|W]]/[[kg]]
|CtoDE=99.9%<ref>{{Cite web | title = BatteryUniversity.com: Charging lithium-ion batteries | first = Isidor | last = Buchmann | publisher = Cadex Electronics Inc. |date=March 2006 | url = http://www.batteryuniversity.com/partone-12.htm}}</ref>
|EtoCP='''2.8-5''' [[Watt hour|Wh]]/[[USD|US$]]<ref>http://www.werbos.com/E/WhoKilledElecPJW.htm (which links to http://www.thunder-sky.com/home_en.asp)</ref>
|SDR=5%-10%/month
|TD=(24-36) months
|CD=~1200 [[Cycle#physics|cycles]]{{Fact|date=January 2008}}
|NomV= 3.6 / 3.7 [[Volts|V]]}}


'''Lithium-ion batteries''' (sometimes abbreviated '''Li-ion batteries''') are a type of [[rechargeable battery]] in which a [[lithium]] ion moves between the [[anode]] and [[cathode]]. The lithium ion moves from the anode to the cathode during discharge and from the cathode to the anode when charging. 

Lithium ion batteries are commonly used in [[consumer electronics]]. They are currently one of the most popular types of battery for portable electronics, with one of the best [[energy density|energy-to-weight ratio]]s, no [[memory effect]], and a slow [[loss of charge]] when not in use. In addition to uses for consumer electronics, lithium-ion batteries are growing in popularity for defense, automotive, and aerospace applications due to their high energy density. However certain kinds of mistreatment may cause Li-ion batteries to explode. 

The three primary functional components of a lithium ion battery are the [[anode]], [[cathode]], and [[electrolyte]], for which a variety of materials may be used. Commercially, the most popular material for the anode is [[graphite]], although materials such as TiS<sub>2</sub> ([[Titanium disulfide]]) were originally used.<ref>[http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=2932&DID=173328 MRS Website : Theme Article - Science and Applications of Mixed Conductors for Lithium Batteries<!-- Bot generated title -->]</ref> The cathode is generally one of three materials: a [[layered oxide]], such as [[cobalt oxide]], a polyanion, such as [[lithium iron phosphate]], or a [[spinel]], such as [[manganese oxide]]. Depending on the choice of material for the anode, cathode, and electrolyte the voltage, capacity, life, and safety of a lithium ion battery can change dramatically. Lithium ion batteries are not to be confused with [[lithium battery|lithium batteries]], the key difference being that lithium batteries are [[Primary_battery|primary batteries]] containing metallic lithium while lithium-ion batteries are [[Secondary_battery|secondary batteries]] containing an intercalation anode material.

==History==
 
Lithium ion batteries were first proposed by [[M Stanley Whittingham|M.S. Whittingham]], then at [[Exxon]], in the 1970s.<ref>[http://dx.doi.org/10.1126/science.192.4244.1126 Electrical Energy Storage and Intercalation Chemistry - WHITTINGHAM 192 (4244): 1126 - Science<!-- Bot generated title -->]</ref> Whittingham used [[titanium sulfide]] as the cathode and [[lithium]] metal as the anode. 

Lithium batteries in which the anode is made from metallic lithium pose severe safety issues. As a result, lithium-ion batteries were developed in which the anode, like the cathode, is made of a material containing lithium ions. Lithium-ion batteries came into reality when [[Bell Labs]] developed a workable graphite anode<ref>{{Ref patent | title = Rechargeable battery | country = US | number = 4304825 | gdate = 1981-12-08}}</ref> to provide an alternative to lithium metal, the [[lithium battery]]. Following groundbreaking cathode research by a team led by [[John Goodenough]]<ref>[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=0&f=S&l=50&d=PTXT&RS=IN%2F%22goodenough%22&Refine=Refine+Search&Refine=Refine+Search&Query=in%2F%22goodenough%2C+john%22 USPTO search for inventions by "Goodenough, John"]</ref>, the first commercial lithium-ion battery was released by [[Sony]] in 1991. The cells utilised [[layered oxide]] chemistry, specifically [[lithium cobalt oxide]]. These batteries revolutionised consumer electronics.

In 1983, Michael Thackeray and coworkers identified manganese [[spinel]] as a cathode material.<ref>http://dx.doi.org/10.1016/0025-5408(83)90138-1</ref> Spinel showed great promise, since it is a low-cost material, has good electronic and lithium ion conductivity, and possesses a three-dimensional structure which gives it good structural stability. Although pure manganese spinel fades with cycling, this can be overcome with additional chemical modification of the material.<ref>http://books.google.com/books?id=k4duxuea3eIC</ref> Manganese spinel is currently used in commercial cells.<ref>[http://www.spectrum.ieee.org/sep07/5490 IEEE Spectrum: Lithium Batteries Take to the Road<!-- Bot generated title -->]</ref>

In 1989, [[Arumugam Manthiram]] and [[John Goodenough]] of the [[University of Texas]] at Austin showed that cathodes containing polyanions, eg. sulfates, produce higher voltage than oxides due to the inductive effect of the polyanion.<ref>http://dx.doi.org/10.1016/0378-7753(89)80153-3</ref> Following this, in 1996 [[John Goodenough|Goodenough]] and co-workers discovered the electrochemical utility of the olivine material [[lithium iron phosphate]], LiFePO<sub>4</sub>. It is an important and emerging cathode material for lithium-ion batteries due in part to its enhanced safety compared to other lithium-ion chemistries. Cells containing lithium iron phosphate cathodes have been commercialised by multiple companies, including [[Phostech]], [[Valence Technology]], [[A123Systems]], [[Aleees]] and [[Lithium Technology Corp.]]

These batteries are generally used in mobile phones,digital clocks etc.

== Electrochemistry ==
The three participants in the electrochemical reactions in a lithium ion battery are the [[anode]], [[cathode]], and [[electrolyte]].

Both the anode and cathode are materials into which and from which lithium can migrate. The process of lithium moving into the anode or cathode is referred to as ''insertion'' (or ''intercalation''), and the reverse process, in which lithium moves out of the anode or cathode is referred to as ''extraction'' (or ''deintercalation''). When  a cell is [[Battery (electricity)#Battery capacity and discharging|discharging]], the lithium is extracted from the anode and inserted into the cathode. When the cell is [[Battery (electricity)#Battery capacity and discharging|charging]], the reverse process occurs: lithium is extracted from the cathode and inserted into the anode. 

The [[anode]] of a conventional Li-ion cell is made from [[carbon]], the [[cathode]] is a metal [[oxide]], and the [[electrolyte]] is a [[lithium]] [[salt]] in an [[organic compound|organic]] [[solvent]]. <ref>Silberberg, M. 2006. ''Chemistry: The Molecular Nature of Matter and Change'', 4th Ed. New York (NY): McGraw-Hill Education. p 935.</ref>

Useful work can only be extracted if electrons flow through an external circuit. Therefore the half reactions are enlightening. The following equations are written in units of moles, making it possible to use the coefficient <math>x</math>. The cathode half reaction (with charging being forwards) is:
<ref name="Gold Peak">{{cite paper|
title=Gold Peak Industries Ltd., Lithium Ion technical handbook|
url=http://www.gpbatteries.com/html/pdf/Li-ion_handbook.pdf|
format=pdf}}</ref>

<center><math>\mathrm{LiCoO_2} \leftrightarrows \mathrm{Li}_{1-x}\mathrm{CoO_2} + x\mathrm{Li^+} + x\mathrm{e^-}</math></center>
The anode half reaction is:
<center><math>x\mathrm{Li^+} + x\mathrm{e^-} + 6\mathrm{C} \leftrightarrows \mathrm{Li_xC_6}</math></center>

This reactions has limits. Overdischarge will supersaturate lithium cobalt oxide, leading to the production of [[lithium oxide]],  <ref>H.C. Choi et al., J. Phys. Chem. B 107 p5806(2003)</ref> possibly by the following irreversible reaction:

<center><math>\mathrm{Li^+} + \mathrm{LiCoO_2} \rightarrow \mathrm{Li_2O} + \mathrm{CoO}</math></center>

<!-- The underlying chemical reaction that allows Li-ion cells to provide electricity is:
<center><math>\mathrm{Li}_{1-x} \mathrm{Co} \mathrm{O}_2 + \mathrm{Li}_{x}\mathrm{C}_6 \leftrightarrows \mathrm{Li}_{1-x}\mathrm{C}_6 + \mathrm{Li}_{x}\mathrm{Co}\mathrm{O}_2 </math></center>

{{Fact|date=February 2007}}-->

<!-- The 'x's need to be there, it shows that there is a pattern, not a set formula! -->
<!-- [Note that in the above reaction the ½ subscripts relate to the empirical formula; naturally, the atoms themselves are never split.] -->
<!-- Chemical formulas refer to moles and moles can be split! -->
<!-- The actual ion involved in the above reaction is <math>\mathrm{Li}_x \mathrm{Co} \mathrm{O}_2</math> --> <!-- this isn't  an ion; it's a neutral compound that acts as the cathode (BUT LAY PEOPLE AREN'T CHEMISTRY MAJORS; WE SHOULD NOT TRY TO CONFUSE THEM!) This part of the article is POORLY written, and obviously you don't remember chemistry from school.  I happen to be a chemist.  Although I am not proficient in the battery industry, I do understand what makes sense and what is nonsense.  You don't know your chemistry! -->

It is important to note that lithium ions themselves are not being oxidized; rather, in a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, [[Cobalt|Co]], in <math>\mathrm{Li}_x \mathrm{Co} \mathrm{O}_2</math> being oxidized from Co<sup>3+</sup> to Co<sup>4+</sup> during charging, and reduced from Co<sup>4+</sup> to Co<sup>3+</sup> during discharge. <!-- This is nonsense: Additionally, the ion complexed with lithium - to form the complex ion - can be that of any of the conventional battery types.  The lithium-containing complex ion is merely an advanced form of the conventional ion; by adding lithium to the conventional ion, to form a complex ion, the original ion becomes more soluble. --> <!-- ("perform" - the batteries do not develop a "memory" or exhibit "discharge" when not in use)--><!-- <ref>A table of common forms of the lithium-complex ions can be found on the first page of: http://www.sei.co.jp/tr_e/t_technical_e_pdf/53-16.pdf (Source: Masatoshi, et.al. Developing of a Life-Long Lithium-Ion Battery For Load Leveling.  SEI Technical Review, Number 56, January 2002, p111-115.)</ref> -->



===Cathodes===

{| class="wikitable"
|-
! Material
! Average Voltage
! Gravimetric Capacity
|-
| LiCoO<sub>2</sub>
| 3.7 V  
| 140 mAh/g 
|-
| LiMnO<sub>2</sub>
| 4.0 V
| 100 mAh/g
|-
| LiFePO<sub>4</sub>
| 3.3 V 
| 170 mAh/g
|-
| Li<sub>2</sub>FePO<sub>4</sub>F
| 3.6 V
| 115 mAh/g
|}

===Electrolytes===

[[Liquid]] [[electrolyte]]s in Li-ion batteries consist of solid [[lithium]]-[[salt]] [[electrolyte]]s, such as [[lithium hexafluorophosphate|LiPF<sub>6</sub>]], [[lithium tetrafluoroborate|LiBF<sub>4</sub>]], or [[lithium perchlorate|LiClO<sub>4</sub>]], and [[organic compound|organic]] [[solvents]], such as [[diethyl ether|ether]]. A liquid [[electrolyte]] conducts Li ions, which acts as a carrier between the [[cathode]] and the [[anode]] when a battery passes an electric current through an external circuit. However, organic solvents are easily decomposed on [[anodes]] during charging, thus preventing battery activation. Nevertheless, when appropriate [[organic solvent]]s are used for electrolytes, the electrolytes are decomposed and form a solid electrolyte interphase (SEI)<ref>Balbuena, P.B., Wang, Y.X., eds. ''Lithium Ion Batteries: Solid Electrolyte Interphase'' 2004 Imperial College Press, London </ref> at first charge that is electrically insulating and high Li-ion conducting. The interphase prevents decomposition of the electrolyte after the second charge. For example, [[ethylene carbonate]] is decomposed at a relatively high voltage, 0.7 V vs. Li, and forms a dense and stable interface. {{Fact|date=February 2007}}

See [[uranium trioxide]] for some details of how the cathode works. While uranium oxides are not used in commercially made batteries, the way in which uranium oxides can reversibly insert cations is the same as the way in which the cathode in many lithium-ion cells work. {{Fact|date=February 2007}}

==Advantages and disadvantages==
===Advantages===
Lithium-ion batteries can be formed into a wide variety of shapes and sizes so as to efficiently fill available space in the devices they power.

Li-ion batteries are  lighter than other equivalent [[secondary battery|secondary batteries]]&mdash;often much lighter. The energy is stored in these batteries through the movement of [[lithium]] [[ion]]s.  However, the bulk of the electrodes are effectively "housing" for the ions and add weight, and in addition "dead weight" from the electrolyte, current collectors, casing, electronics and conductivity additives reduce the charge per unit mass to little more than that of other rechargeable batteries. A key advantage of using Li-ion chemistry is the high [[open circuit voltage]] that can be obtained in comparison to [[aqueous battery|aqueous batteries]] (such as [[lead acid]], [[NiMH|nickel metal hydride]] and [[NiCd|nickel cadmium]]). {{Fact|date=February 2007}} <!-- NO! At 3.6V per cell, the electromotive potential is HUGE compared to other cell types - 0.6V for Pb-Acid, 1.2V for NiCd, ~1.4 for Ni-MH, typical 1.5V for C-Zn. Power density = (voltage x current)/volume = power/volume = BIG for Li-ion at least partially because of the high OC voltage, meaning lots of power in a small space. The fact that Li is element #3, and therefore super lightweight, is merely a bonus. -->

Li-ion batteries do not suffer from the [[memory effect]]. They also have a low self-discharge rate of approximately 5% per month, compared with over 30% per month in common [[nickel metal hydride]] batteries ([[Low self-discharge NiMH batteries]] have much lower values, around 1.25% per month; they can still hold 85% of their charge, after one year) and 10% per month in [[nickel cadmium]] batteries.

According to one manufacturer, Li-ion cells (and, accordingly, "dumb" Li-ion batteries) do not have any [[self-discharge]] in the usual meaning of this word.<ref name="Gold Peak">{{cite paper|
title=Gold Peak Industries Ltd., Lithium Ion technical handbook|
url=http://www.gpbatteries.com/html/pdf/Li-ion_handbook.pdf|
format=pdf}}</ref>  What looks like a self-discharge in these batteries is a permanent loss of capacity, described in more detail below. On the other hand, "smart" Li-ion batteries do self-discharge, due to the small constant drain of the built-in voltage monitoring circuit. This drain is the most important source of self-discharge in these batteries.

===Disadvantages===
{{Refimprovesect|date=October 2007}}
A unique drawback of the Li-ion battery is that its life span is dependent upon aging from time of manufacturing (shelf life) regardless of whether it was charged, and not just on the number of charge/discharge cycles. So an older battery will not last as long as a new battery due solely to its age, unlike other batteries. This drawback is not widely published.<ref>{{Cite web | first = Isidor | last = Buchmann | title = Will Lithium-Ion batteries power the new millennium? | publisher = Isidor Buchmann (CEO of Cadex Electronics Inc.) | url = http://www.buchmann.ca/Article5-Page1.asp}}</ref>

At a 100% charge level, a typical Li-ion [[laptop]] battery that is full most of the time at 25 degrees [[Celsius]] or 77 degrees [[Fahrenheit]] will irreversibly lose approximately 20% capacity per year. However, a battery stored inside a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures than 25 °C, which will significantly shorten its life. The capacity loss begins from the time the battery was manufactured, and occurs even when the battery is unused. Different storage temperatures produce different loss results: 6% loss at 0 °C (32 °F), 20% at 25 °C (77 °F), and 35% at 40 °C (104 °F). When stored at 40% - 60% charge level, these figures are reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively.

Under certain temperature conditions, the batteries have a tendency to become damaged and can sometimes never fully recharge again. In certain situations where the temperature is too cold (below the recommended battery temperature) the battery will still hold its charge but cannot be recharged as a result of the cold temperature. This is most common in smaller batteries such as cellular phones and handheld devices.

As batteries age, their internal resistance rises. This causes the voltage at the terminals to drop under load, reducing the maximum current that can be drawn from them. 
Eventually they reach a point at which the battery can no longer operate the equipment it is installed in for an adequate period.

High drain applications such as powertools may require the battery to be able to supply a current of (15 h<sup>-1</sup>)C - 15/hour times "C" - the battery capacity in [[Ampere hours]], whereas [[MP3]] players may only require (0.1 h<sup>-1</sup>)C (discharging in 10 hours). 
With similar technology, the MP3 battery can tolerate a much higher internal resistance, so will have an effective life of many more cycles.<ref name="prolong life">{{Cite web | title = BatteryUniversity.com:  How to prolong lithium-based batteries | first = Isidor | last = Buchmann | publisher = Cadex Electronics Inc. |date=September 2006 | url = http://www.batteryuniversity.com/parttwo-34.htm}}</ref>

Li-ion batteries can even go into a state that is known as ''deep discharge''. At this point, the battery may take a very long time to recharge. For example, a laptop battery that normally charges fully in 3 hours may take up to 42 hours to recharge. Or the deep discharge state may be so severe that the battery will never come back to life. Deep discharging only takes place when products with rechargeable batteries are left unused for extended periods of time (often 2 or more years) or when they are fully discharged so often that they can no longer hold a charge. This makes Li-ion batteries unsuitable for back-up applications where they may become completely discharged.

A stand-alone Li-ion cell must never be discharged below a certain voltage to avoid irreversible damage. Therefore all Li-ion battery systems are equipped with a circuit that shuts down the system when the battery is discharged below the predefined threshold.<ref name="Gold Peak"/> It should thus be impossible to "deep discharge" the battery in a properly designed system during normal use. This is also one of the reasons Li-ion cells are rarely sold as such to consumers, but only as finished batteries designed to fit a particular system.

When the voltage monitoring circuit is built inside the battery (a so-called "smart" battery) rather than the equipment, it continuously draws a small current from the battery even when the battery is not in use; furthermore, the battery must not be stored fully discharged for prolonged periods of time, to avoid damage due to deep discharge.

Li-ion batteries are not as durable as [[nickel metal hydride battery|nickel metal hydride]] or [[nickel-cadmium battery|nickel-cadmium]] designs and can be extremely dangerous if mistreated. They are usually more expensive.

Li-ion chemistry is not as safe as [[nickel metal hydride battery|nickel metal hydride]] or [[nickel-cadmium battery|nickel-cadmium]], and a Li-ion cell requires several mandatory safety devices to be built in before it can be considered safe for use outside of a laboratory. These are: shut-down separator (for overtemperature), tear-away tab (for internal pressure), vent (pressure relief), and thermal interrupt (overcurrent/overcharging).<ref name="Gold Peak"/> The devices take away useful space inside the cells, and add an additional layer of unreliability. Typically, their action is to permanently and irreversibly disable the cell.

Approximately 1% of Li-ion batteries are the subject of recalls.<ref>{{Cite news | title = Japanese experts demand change to make phones and laptops safe | publisher = The Times | first = Leo | last = Lewis |date=August 21, 2007 | url = http://business.timesonline.co.uk/tol/business/industry_sectors/technology/article2295743.ece}}</ref> .

The number of safety features can be compared with that of a [[nickel metal hydride]] cell, which only has a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve.{{Fact|date=February 2007}}

==Specifications and design==

[[Image:Lithium Ion.JPG|thumb|right|A lithium-ion battery from a mobile phone.]]

* Specific energy density: 150 to 200 [[watt-hour|Wh]]/kg (540 to 720 [[kilojoule|kJ]]/kg)
* Volumetric energy density: 250 to 530 Wh/l (900 to 1900 J/cm³)
* Specific power density: 300 to 1500 W/kg (@ 20 seconds<ref>http://www.e-one.com.tw/News_2005_e.htm</ref> and 285 Wh/l)

Because lithium-ion batteries can have a variety of cathode and anode materials, cell specifications, such as the energy density and voltage vary from chemistry to chemistry. 


Lithium ion batteries with a lithium iron phosphate cathode and graphite anode have a nominal [[open-circuit voltage]] of 3.6 [[volt|V]] and a typical charging voltage of 4.2 V. The charging procedure is done at constant voltage with current limiting circuitry.  This means charging with constant current until a voltage of 4.2 V is reached by the cell and continuing with a constant voltage applied until the current drops close to zero.  Typically the charge is terminated at 7% of the initial charge current.  In the past, lithium-ion batteries could not be fast-charged and typically needed at least two hours to fully charge.  Current generation cells can be fully charged in 45 minutes or less; some Lithium-Ion variants can reach 90% in as little as 10 minutes.<ref>[http://home.businesswire.com/portal/site/google/index.jsp?ndmViewId=news_view&newsId=20070530005396 AeroVironment Achieves Electric Vehicle Fast Charge Milestone] Test Rapidly Recharges a Battery Pack Designed for Use in Passenger Vehicles. 10 Minute Re-Charge Restores Enough Energy to Run Electric Vehicle for Two Hours at 60 Miles Per Hour</ref>

==Commercialization of Lithium Ion Batteries==
{{expert}}{{Inappropriate tone|date=December 2007}}

=== Lithium Cobalt Oxide Cathodes ===

Lithium ion batteries were first commercialized by Sony in 1991.<ref>http://books.google.com/books?id=k4duxuea3eIC</ref> The cells utilized a lithium [[cobalt oxide]] cathode and a [[graphite]] anode. Sony and Sanyo are the leading producers of lithium ion batteries.<ref>[http://www.sony.net/Fun/SH/1-24/h3.html Sony Global - Sony History<!-- Bot generated title -->]</ref><ref>http://www.aei-online.org/automag/techbriefs/10-2006/1-114-10-16.pdf</ref> A variety of Chinese, Japanese, and South Korean companies produce cells based on the lithium cobalt oxide cathode chemistry.<ref>[http://www.spectrum.ieee.org/sep07/5490/2 IEEE Spectrum: Lithium Batteries Take to the Road<!-- Bot generated title -->]</ref>

=== Manganese Spinel Cathodes===

[[LG Chem|LG]], which is the third largest producer of lithium ion batteries, uses the lithium manganese spinel for its cathode. It is working with its subsidiary [[CPI]] to commercialize lithium ion batteries containing manganese spinel for [[Hybrid electric vehicle|HEV]] applications.<ref>http://www.aei-online.org/automag/techbriefs/10-2006/1-114-10-16.pdf</ref> Several other companies are also working on manganese spinel, including [[NEC]] and [[Samsung]].<ref>[http://www.spectrum.ieee.org/sep07/5490/2 IEEE Spectrum: Lithium Batteries Take to the Road<!-- Bot generated title -->]</ref>

===Lithium Iron Phosphate Cathodes ===

The [[University of Texas]] first licensed its patent for lithium iron phosphate cathodes to [[HydroQuebec]].<ref>[http://bicklebrewer.com/index.php?id=486&backPID=485&begin_at=125&tt_news=433 Bickel & Brewer - A law firm devoted exclusively to the resolution of complex commercial disputes. Bickel & Brewer was formed with a singular goal: to serve clients in significant, disputed matters that involve substantial dollar or business exposures...: Detail<!-- Bot generated title -->]</ref> [[Phostech]] was later spun-off from [[Hydroquebec]] for the sole development of lithium iron phosphate. 

[[Valence Technology]], located in Austin, TX, is also working on lithium iron phosphate cells.  Since March 2005, the [[Segway Personal Transporter]] has been shipping with extended-range lithium-ion batteries<ref>http://www.segway.com/personal-transporter/lithium_ion.html</ref> made by Valence Technology using iron phosphate cathode materials. Segway, Inc. chose to build their large-format battery with this cathode material because of its improved safety over metal-oxide materials.

In November 2005, [[A123Systems]] announced<ref>http://www.a123systems.com/html/news/articles/051102_news.html</ref> the development of lithium iron phosphate cells based on research licensed from MIT.<ref>[http://www.greencarcongress.com/2005/11/a123systems_lau.html#more Green Car Congress: A123Systems Launches New Higher-Power, Faster Recharging Li-Ion Battery Systems<!-- Bot generated title -->]</ref><ref>[http://autos.groups.yahoo.com/group/gridable-hybrids/message/2099 Yahoo! Groups<!-- Bot generated title -->]</ref> While the battery has slightly lower energy density that other competing Lithium Ion technologies, a 2 Ahr cell can provide a peak of 70 Amps without damage and operate at temperatures above 60 degrees C.  Their first cell is in production (1Q/2006) and being used in consumer products including [[DeWalt]] power tools, aviation products, automotive hybrid systems and [[PHEV]] conversions.

=== Titanate Anodes===

[[Altairnano]], a small firm based in [[Reno, Nevada]], has announced a nano-sized [[titanate]] [[electrode]] material for lithium-ion batteries. It is claimed the prototype battery has three times the power output of existing batteries and can be fully charged in six minutes. However the energy capacity is about half that of normal li-ion cells. The company also says the battery can handle approximately 20,000 recharging cycles, so durability and battery life are much longer, estimated to be around 20 years or four times longer than regular lithium-ion batteries. The batteries can operate from -50 °C to over 75 °C and will not explode or result in thermal runaway even under severe conditions because they do not contain graphite-coated-metal anode electrode material.<ref>[http://www.altairnano.com/documents/AltairnanoEDTAPresentation.pdf Microsoft PowerPoint - 061125 Altair EDTA Presentation<!-- Bot generated title -->]</ref> The batteries are currently being tested in a new production car made by [[Phoenix Motorcars]] which was on display at the 2006 SEMA motorshow.

[[Enerdel]], which is jointly owned by [[Ener1]] and [[Delphi Corporation|Delphi]], is working to commercialize cells containing a titanate anode and manganese spinel cathode.<ref>[http://www.ener1.com/enerdel.html Welcome to Ener1<!-- Bot generated title -->]</ref> Although the cells show excellent thermal properties and cyclability, their low voltage may hamper commercial success.<ref>[http://enerdel.com/pdfs/EnerDelTechnicalPresentation.pdf Microsoft PowerPoint - EnerDel Technical Presentation.ppt [Read-Only&#93;<!-- Bot generated title -->]</ref>

All these formulations involve new [[electrode]]s (anodes or cathodes).  By increasing the effective electrode area—thus decreasing the internal resistance of the battery—the current can be increased during both use and charging.  This is similar to developments in [[ultracapacitor]]s.  Therefore, the battery is capable of delivering more power (watts); however, the battery's capacity ([[ampere-hour]]s) is increased only slightly.

== Breakthrough Research ==

In April 2006, a group of scientists at [[MIT]] announced a process which uses viruses to form nano-sized wires.  These can be used to build ultrathin lithium-ion batteries with three times the normal energy density.<ref>Science Express (preprint) http://www.sciencemag.org/cgi/content/abstract/1122716</ref>

As of June 2006, researchers in France have created nanostructured battery electrodes with several times the energy capacity, by weight and volume, of conventional electrodes.<ref>[http://www.technologyreview.com/read_article.aspx?ch=nanotech&sc=&id=17017&pg=1 Technology Review: Higher-Capacity Lithium-Ion Batteries<!-- Bot generated title -->]</ref>

In the September 2007 issue of Nature, researchers from the University of Waterloo, Canada, reported a new  cathode chemistry, whereby the hydroxide group in the iron phosphate cathode was replaced by fluorine. [http://www.nature.com/nmat/journal/v6/n10/abs/nmat2007.html] The advantages seem to be two-fold. First, there is less volume change in the cathode over a charge cycle which indicates a possibility for longer battery life. Second, the chemistry allows the substitution of Sodium or a Sodium/Lithium mixture for the Lithium in the battery (hence their reference to it as an [[Alkali-Ion]] battery).

In November 2007, [[Subaru]] unveiled their concept G4e electric vehicle with a lithium [[vanadium]] oxide based lithium ion battery, promising double the energy density of a conventional lithium ion battery (lithium cobalt oxide and graphite).[http://www.gizmag.com/go/8281/]  In the lab, Lithium vanadium oxide anodes, paired with lithium cobalt oxide cathodes, have achieved 745Wh/l, nearly three times the volumetric energy density of conventional lithium ion batteries. [http://techon.nikkeibp.co.jp/article/HONSHI/20080129/146549/]

In December 2007, researchers at Stanford university reported creating a lithium ion battery with [[nanowire battery|ten times the energy density]] (amount of energy available by weight) through using silicon nanowires deposited on stainless steel as the anode.  The battery takes advantage of the fact that silicon can hold large amounts of lithium, and helps alleviate the longstanding problem of cracking by the small size of the wires. [http://news.google.com/news/url?sa=t&ct=us/1-0&fp=47694201ca330634&ei=IIRpR5LDDYmk-wGuwqWTBg&url=http%3A//www.sciencedaily.com/releases/2007/12/071219103105.htm&cid=1125016979&sig2=Mpk65OqNCcZim_rTMXCbBw]  To gain a tenfold improvement in energy density, the cathode would need to be improved as well; however, just improving the anode as such could provide "several" times the energy density, according to the team.  The team leader, Yi Cui, expects to be able to commercialize the technology in about five years.[http://www.gm-volt.com/2007/12/21/gm-voltcom-interview-with-dr-cui-inventor-of-silicon-nanowire-lithium-ion-battery-breakthrough]. 

Silicon nanowire lithium ion battery has a anode made out of Silicon nano wires. Having a large capacitive anode wont increase the capacity of the battery as predicted by the author when the cathode material is far less capacitive than the anode. Current Li-ion capacity is mainly limited by the capacity of the cathode materials.

==Guidelines for prolonging Li-ion battery life==

* Unlike [[nickel-cadmium battery|Ni-Cd batteries]], lithium-ion batteries should be charged early and often. However, if they are not used for a long time, they should be brought to a charge level of around 40% - 60%.  Lithium-ion batteries should not be frequently fully discharged and recharged ("deep-cycled") like Ni-Cd batteries, but this ''is'' necessary after about every 30th recharge to recalibrate any external electronic "fuel gauge" (e.g. State Of Charge meter). This prevents the fuel gauge from showing an incorrect battery charge.<ref name="prolong life"/>
* Li-ion batteries should never be [[wikt:depleted|depleted]] to below their minimum voltage, 2.4v to 3.0v per cell.
* Li-ion batteries should be kept cool. Ideally they are stored in a refrigerator. Aging will take its toll much faster at high temperatures. The high temperatures found in cars cause lithium-ion batteries to degrade rapidly.
* Li-ion batteries should not be frozen <ref>{{cite book|
title=Characteristics and Behavior of 1M LiPF6 1EC:1DMC Electrolyte at Low Temperatures|
author=L.M. Cristo, T. B. Atwater|
publisher=U.S. Army Research|
location=Fort Monmouth, NJ}}</ref> (most lithium-ion battery electrolytes freeze at approximately −40&nbsp;°C; however, this is much colder than the lowest temperature reached by household freezers).
* Li-ion batteries should be bought only when needed, because the aging process begins as soon as the battery is manufactured.<ref name="prolong life"/>
* When using a notebook computer running from fixed line power over extended periods, the battery should be removed,<ref>[http://batteryuniversity.com/parttwo-34.htm How to prolong lithium-based batteries<!-- Bot generated title -->]</ref> and stored in a cool place so that it is not affected by the heat produced by the computer. <!--- The link <ref name="prolong life"/> http://www.batteryuniversity.com/parttwo-34.htm  doesn't say that the (Li-ion) battery should be removed from the notebook when using from fixed line; this may have averse effect on the notebook and/or is not recommended by notebook manufacturers  --->

===Storage temperature and charge===

Storing a Li-ion battery at the correct temperature and charge makes all the difference in maintaining its storage capacity. The following table shows the amount of ''permanent'' capacity loss that will occur after storage at a given charge level and temperature.

{| class="wikitable" align="right" style="margin-left:2em;"
|+Permanent Capacity Loss versus Storage Conditions
|- align="center"
! Storage Temperature || 40% Charge || 100% Charge
|-
! 0 °C (32 °F)
|| '''2%''' loss after 1 year || '''6%''' loss after 1 year
|-
! 25 °C (77 °F)
|| '''4%''' loss after 1 year || '''20%''' loss after 1 year
|-
! 40 °C (104 °F)
|| '''15%''' loss after 1 year ||  '''35%''' loss after 1 year
|-
! 60 °C (140 °F)
|| '''25%''' loss after 1 year ||  '''40%''' loss after 3 months
|-
| colspan="3" align="center" | ''Source: BatteryUniversity.com<ref name="prolong life"/>
|}

It is significantly beneficial to avoid storing a lithium-ion battery at full charge. A Li-ion battery stored at 40% charge will last many times longer than one stored at 100% charge, particularly at higher temperatures.<ref name="prolong life"/>

If a Li-ion battery is stored with too low a charge, there is a risk of allowing the charge to drop below the battery's low-voltage threshold, resulting in an unrecoverable dead battery. Once the charge has dropped to this level, recharging it can be dangerous. Some batteries therefore feature an internal safety circuit which will prevent charging in this state, and the battery will be for all practical purposes dead. {{Fact|date=February 2007}}

In circumstances where a second Li-ion battery is available for a given device, it is recommended that the unused battery be discharged to 40% and placed in the refrigerator to prolong its shelf life.  While the battery can be used or charged immediately, some Li-ion batteries will provide more energy when brought to room temperature.

===Prolonging Life in Multiple Cells Through Cell Balancing===

Analog front ends that balance cells and eliminate mismatches of cells in series or parallel significantly improve battery efficiency and increase the overall pack capacity. As the number of cells and load currents increase, the potential for mismatch also increases. There are two kinds of mismatch in the pack: State-of-Charge (SOC) and capacity/energy (C/E) mismatch. Though the SOC mismatch is more common, each problem limits the pack capacity (mAh) to the capacity of the weakest cell. 

It is important to recognize that the cell mismatch results more from limitations in process control and inspection than from variations inherent in the Lithium Ion chemistry. The use of cell balancing can improve the performance of series connected Li-ion Cells by addressing both SOC and C/E issues.<ref>[http://www.intersil.com/data/an/an1333.pdf AN1333<!-- Bot generated title -->]</ref>  SOC mismatch can be remedied by balancing the cell during an initial conditioning period and subsequently only during the charge phase. C/E mismatch remedies are more difficult to implement and harder to measure and require balancing during both charge and discharge periods.

'''Cell Balancing'''

Cell balancing is defined as the application of differential currents to individual cells (or combinations of cells) in a series string. Normally, of course, cells in a series string receive identical currents. A battery pack requires additional components and circuitry to achieve cell balancing. However, the use of a fully integrated analog front end for cell balancing<ref>[http://www.intersil.com/cda/deviceinfo/0,1477,ISL9208,0.html ISL9208 Multi-Cell Li-ion Battery Pack OCP/Analog Front End<!-- Bot generated title -->]</ref> reduces the required external components to just balancing resistors. 

This type of solution eliminates the need for discrete capacitors, diodes and most other resistors to achieve balance. 

Battery pack cells are balanced when all the cells in the battery pack meet two conditions. 

1. If all cells have the same capacity, then they are balanced when they have the same relative State of Charge (SOC.) In this case, the Open Circuit Voltage (OCV) is a good measure of the SOC. If, in an out of balance pack, all cells can be differentially charged to full capacity (balanced), then they will subsequently cycle normally without any additional adjustments. This is mostly a one shot fix.

2. If the cells have different capacities, they are also considered balanced when the SOC is the same. But, since SOC is a relative measure, the absolute amount of capacity for each cell is different. To keep the cells with different capacities at the same SOC, cell balancing must provide differential amounts of current to cells in the series string during both charge and discharge on every cycle.

== Safety ==
Lithium-ion batteries can rupture, ignite, or explode when exposed to high temperature environments, for example in an area that is prone to prolonged direct sunlight.<ref>http://www.tayloredge.com/museum/mymuseum/sciencefun/li-ion_003.mov</ref> Short-circuiting a Li-ion battery can cause it to ignite or explode, and as such, any attempt to open or modify a Li-ion battery's casing or circuitry is dangerous.  Li-ion batteries contain safety devices that protect the cells inside from abuse, and, if damaged, can cause the battery to ignite or explode.

Contaminants inside the cells can defeat these safety devices. For example, the mid-2006 recall of approximately 10 million Sony batteries used in [[Dell]], [[Sony]], [[Apple Computer|Apple]], [[Lenovo]]/[[IBM]], [[Panasonic]], [[Toshiba]], [[Hitachi, Ltd.|Hitachi]], [[Fujitsu]] and [[Sharp Corporation|Sharp]] laptops was stated to be as a consequence of internal contamination with metal particles. Under some circumstances, these can pierce the separator, causing the cell to short, rapidly converting all of the energy in the cell to heat resulting in an exothermic oxidizing reaction, increasing the temperature to a few hundred degrees Celsius in a fraction of a second.<ref>[http://www.theinquirer.net/default.aspx?article=32550 Dell laptop explodes at Japanese conference - The INQUIRER<!-- Bot generated title -->]</ref> This causes the neighboring cells to heat up, causing a chain thermal reaction.

The mid-2006 Sony laptop battery recall was not the first of its kind, however it was the largest to date. During the past decade there have been numerous recalls of lithium-ion batteries in cellular phones and laptops owing to overheating problems.  In October 2004, [[Kyocera Wireless]] recalled approximately 1 million batteries used in cellular phones, due to counterfeit batteries produced in Kyocera's name.<ref>{{cite press release | title = Kyocera Launches Precautionary Battery Recall, Pursues Supplier of Counterfeit Batteries | publisher = [[Kyocera Wireless]] | date = [[2004-10-28]] | url = http://www.kyocera-wireless.com/news/20041028_2.htm | accessdate =  }}</ref>  In December 2006, [[Dell]] recalled approximately 22,000 batteries from the U.S. market.<ref>Tullo, Alex. "Dell Recalls Lithium Batteries." Chemical and Engineering News [[21 August]] [[2006]]: 11.</ref>  In March 2007, Lenovo recalled approximately 205,000 9-cell lithium-ion batteries due to an explosion risk. In August 2007, [[Nokia]] recalled over 46 million lithium-ion batteries, warning that some of them might overheat and possibly explode.<ref>http://en.wikinews.org/wiki/Nokia_issues_BL-5C_battery_warning%2C_offers_replacement</ref> There was an incident in the [[Philippines]] involving a [[Nokia N91]], which uses the BL-5C battery.<ref>[http://www.mukamo.com/nokia-n91-cell-phone-explodes/ Nokia N91 cell phone explodes<!-- Bot generated title -->]</ref> 

It is possible to replace the [[lithium cobalt oxide]] cathode material in li-ion batteries with [[lithiated metal phosphate]] cathodes that are not as sensitive to temperature, and so are less prone to explode. This also extends their [[shelf life]]. However,  currently these 'safer' li-ion batteries are mainly destined for [[electric car]]s and other [[large-capacity battery]] applications, where the safety issues are more critical. Unfortunately, a problem with these 'safer' li-ion batteries is that lithiated metal phosphate batteries hold only about 75 percent as much energy.<ref>[http://www.nytimes.com/2006/09/01/opinion/01cringely.html Safety Last - New York Times<!-- Bot generated title -->]</ref>

Another option is to use [[manganese oxide]] or [[iron phosphate]]  cathode.<ref>[http://www.technologyreview.com/Energy/18833/ Technology Review: New Batteries Readied for GM's Electric Vehicle<!-- Bot generated title -->]</ref>

<!--
==Real World Testing==

[[Image:Team Moore.jpg|thumb|One of 240 laps, June 13, 2007]]

[http://www.ampmobiles.com Ampmobiles'] Mike Moore takes a spin around the track in Concord, NC on June 13<sup>th</sup>, 2007.  The tests were conducted at the Concord speedway in Concord, NC during the week of June 11<sup>th</sup>, 2007.  Simultaneous tests were being performed in Virginia as well.  The purpose of the tests was to proof the latest product shipped in by [http://www.LionEV.com LionEV], the [[Lithium Iron Phosphate]] softpack.

The tests and records of laps proved the packs capable of providing over 2,000 Amps of current, with a capacity of well over 200Ah.  The tests resulted in further refinements to the packs.  Additional testing on the production batteries are expected to be completed by the end of September, 2007.

[[Lithium iron phosphate battery|Lithium Iron Phosphate cells]] are an extension of the original Lithium Ion family.  Their superior stability improves the safety over their predecessors.  

See [[Lithium Iron Phosphate]]

Driver, Mike Moore<br /> 
Video camera, Paula Moore<br />
Statistics, Don Wood<br />
LionEV Representative, Ken Curry
-->

==See also==
* [[Battery balancer]]
* [[Battery holder]]
* [[Battery recycling]]
* [[Lithium battery]] 
* [[Lithium iron phosphate battery]] - LiFePO<sub>4</sub>
* [[Valence Technology]]

==References==
{{reflist|2}}

==External links==
*[http://www.batteryuniversity.com/partone-12.htm Charging the Lithium Ion Battery].
*[http://electronics.howstuffworks.com/lithium-ion-battery.htm How Lithium-ion Batteries Work].
*[http://news-service.stanford.edu/news/2008/january9/nanowire-010908.html Stanford's nanowire battery holds 10 times the charge of existing ones], Stanford Report, ''December 18, 2007''
*[http://www.e-articles.info/e/a/title/The-Lithium-Ion-Battery/ The Lithium Ion Battery].
*[http://www.e-articles.info/e/a/title/Advantages-and-Limitations-of-the-Lithium-Polymer-Battery/ Advantages and Limitations of the Lithium Polymer Battery].

[[Category:Lithium-ion batteries| ]]
[[Category:Laptops]]
[[Category:Corporate scandals]]
[[Category:Recyclable materials]]

{{GalvanicCells}}

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