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Lithium-ion polymer battery 1

Lithium-ion polymer battery

A Lithium-Ion Polymer Battery used to power a mobile

phone

specific energy 130 € 200 W€h/kg

energy density 300 W€h/L

specific power up to 7.1 kW/kg

Charge/discharge efficiency  99.8%

Energy/consumer-price 2.8 € 5 W€h/US$

Self-discharge rate 5%/month

Time durability 24 € 36 months

Cycle durability  >1000 cycles

Nominal cell voltage 3.7 V

Lithium-ion polymer batteries, polymer lithium ion, or more commonly lithium polymer batteries (abbreviated

Li-poly, Li-Pol, LiPo, LIP, PLI or LiP) are rechargeable batteries (secondary cell batteries). Normally batteries arecomposed of several identical secondary cells in parallel addition to increase the discharge current capability.

Design origin

This type has technologically evolved from lithium-ion batteries. The primary difference is that the lithium-salt

electrolyte is not held in an organic solvent but in a solid polymer composite such as polyethylene oxide or

polyacrylonitrile. The advantages of Li-ion polymer over the lithium-ion design include potentially lower cost of 

manufacture, adaptability to a wide variety of packaging shapes, and ruggedness. Lithium-ion polymer batteries

started appearing in consumer electronics around 1996.

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Lithium-ion polymer battery 2

Technology

An experimental Li Ion Polymer Battery made by

NASA

Cells sold today as polymer batteries are pouch cells. Unlike

lithium-ion cylindrical cells, which have a rigid metal case, pouch cells

have a flexible, foil-type (polymer laminate) case. In cylindrical cells,

the rigid case presses the electrodes and the separator onto each other;

whereas in polymer cells this external pressure is not required because

the electrode sheets and the separator sheets are laminated onto each

other.

Since individual pouch cells have no strong metal casing, by

themselves they are over 20% lighter than equivalent cylindrical cells.

However, all Li-Ion cells expand at high levels of SOC; if uncontained,

this may result in delamination, and reduction of reliability and cycle

life; the case of cylindrical cells provides that containment, while

pouch cells, by themselves, are not contained. Therefore, to achieve the

rated performance, a battery composed of pouch cells must include an overall, strong, external casing to retain its

shape.[1]

The voltage of a Li-poly cell varies from about 2.7 V (discharged) to about 4.23 V (fully charged), and Li-poly cells

have to be protected from overcharge by limiting the applied voltage to no more than 4.235 V per cell used in a

series combination. Overcharging a Li-poly battery will probably cause explosion or fire. During discharge on load,

the load has to be removed as soon as the voltage drops below approximately 3.0 V per cell (used in a series

combination), or else the battery will subsequently no longer accept a full charge and may experience problems

holding voltage under load. This can be achieved, as with other lithium-ion batteries, also harmed by under- and

over-voltage, by circuitry that prevents overcharge and deep discharge.

Early in its development, lithium polymer technology had problems with internal resistance. Other challenges

include longer charge times and slower maximum discharge rates compared to more mature technologies. Li-poly

batteries typically require more than an hour for a full charge. Recent design improvements have increased

maximum discharge currents from two times to 15 or even 30 times the cell capacity (discharge rate in amperes, cell

capacity in ampere-hours). In December 2007 Toshiba announced a new design offering a much faster rate of charge

(about 5 minutes to reach 90%). These cells were released onto the market in March 2008 and are expected to have a

dramatic effect on the power tool and electric vehicle industries, and a major effect on consumer electronics.[2]

When compared to the lithium-ion battery, Li-poly has a greater life cycle degradation rate. However, in recent

years, manufacturers have been declaring upwards of 500 charge-discharge cycles before the capacity drops to 80%

(see Sanyo). Another variant of Li-poly cells, the "thin film rechargeable lithium battery", has been shown to provide

more than 10,000 cycles.

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Lithium-ion polymer battery 5

Charging

LiPoly batteries must be charged carefully. The basic process is to charge at constant current until each cell reaches

4.2 V; the charger must then gradually reduce the charge current while holding the cell voltage at 4.2 V until the

charge current has dropped to 10% of the initial charge rate, at which point the battery is considered 100% charged.

Balance charging simply means that the charger monitors the voltage of each cell in a pack and varies the charge on

a per-cell basis so that all cells are brought to the same voltage.

It is important to note that trickle charging is not acceptable for lithium batteries; Li-ion chemistry cannot accept an

overcharge without causing damage to the cell, possibly plating out lithium metal and becoming hazardous.[4]

Most

manufacturers claim a maximum and minimum voltage of 4.23 and 3.0 volts per cell. Taking any cell outside these

limits can reduce the cell's capacity and ability to deliver full rated current.

Most dedicated lithium polymer chargers use a charge timer for safety; this cuts the charge after a predefined time

(typically 90 minutes).

Storage

Unlike certain other types of batteries, lithium ion batteries can be stored for one or two months without significantly

losing charge. However, if storing for long periods, manufacturers recommend discharging the battery to 40% of full

charge.[5]

 [6]

In addition, other sources recommend refrigerating (but not freezing) the cell.[7]

See also

• Thin-film

• Lithium air battery

External links

• BatteryUniversity.com [8]

• Electropaedia on Lithium Battery Manufacturing[9]

• Electropaedia on Lithium Battery Failures[10]

• Designing Multi-Cell Li-ion Battery Packs Using the ISL9208 Analog Front End[11]

.

• AT&T To Replace 17,000 Batteries[12]

• ProtoTalk.net - Lithium Polymer (Lipo) Battery Guide[13]

• ThunderPower's Safety Warnings[14]

References

[1] http:/   /  liionbms.com/  php/  pouch_tips. php#Side_clamping[2] Toshiba (2007-12-11). "Toshiba to Launch Innovative Rechargeable Battery Business" (http:/   /  www. toshiba. co.  jp/  about/  press/  2007_12/ 

pr1101. htm). Press release. . Retrieved 2009-06-25.

[3] "Hyundai To Unveil 2011 Sonata at 2010 Detroit Auto Show", 'Edmunds.com', retrieved 7/24/2009 http:/   /  www. edmunds.  com/  insideline/ 

do/  News/  articleId=152807

[4] PowerStream.com, 2010-03-17, http:/   /  www. powerstream. com/  li. htm

[5] http:/   /  thunderpowerrc. com/  PDF/  THPSafetyWarnings. pdf 

[6] http:/   /  www. apple. com/  batteries/  notebooks.  html

[7] Buchaman, Isidor, "Batteries in a Portable World", chapter 10, page 6, http:/   /  www. buchmann. ca/  Chap10-page6. asp„

[8] http:/   /  www. batteryuniversity. com/ 

[9] http:/   /  www. mpoweruk. com/  battery_manufacturing. htm

[10] http:/   /  www. mpoweruk. com/  lithium_failures. htm

[11] http:/   /  www. intersil. com/  data/  an/  an1333.  pdf 

[12] http:/   /  www. lightreading. com/  document. asp?doc_id=143185

[13] http:/   /  prototalk. net/  forums/  showthread. php?t=22

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Lithium-ion polymer battery 6

[14] http:/   /  thunderpowerrc. com/  PDF/  THPSafetyWarnings. pdf 

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Article Sources and Contributors 7

Article Sources and ContributorsLithium-ion polymer battery  Source: http://en.wikipedia.org/w/index.php?oldid=381967199 Contributors: A. B., Achimd, Adam Schwing, Adam1213, AdultSwim, Agent007bond, Ahbond,

Ahunt, Alexcmag, Alexinoz, Alexwcovington, Amikake3, Animum, Anonymi, Antifumo, Aranel, Aron1, Barutok, Be at peace, Benklop, Blah232, Bongwarrior, Boso1111111, Boulty,

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EdDavies, Electron16, Electropaedia, Etxrge, Ferrari-eric, Firecyclone81, Floodo1, Francis Flinch, Freexky, Fresheneesz, Gary King, Gene Nygaard, GeoffatAkhter, Gogo Dodo, GraemeL,

Gregmg, Grentz, Gyrobo, Hadal, Honestman2010, Hooperbloob, HumphreyW, Huntster, HybridBoy, Imjustahyphen, Internetexploder, Intgr, Isaacjohnson, Jaimie Henry, JasonCW, Jernejl, Jmc,

Jonathan.s.kt, Jrockley, Jsmathew, JustinWick, KD5TVI, Kangy, Karn, Kelly Martin, King Lopez, Knifle, KrMolot, Kralizec!, Kristoferb, LEX LETHAL, Leigh8959, Leonard G., Lucky 6.9,Mac, Maltzer, MartinSpacek, Mattbayly, Matthew CB Allen, Medovina, Mikiemike, Mini-Geek, Mkouklis, Mnmngb, Mooreaa, Mor, Mschel, N419BH, NYCDA, Nannen, Neet nl, Ng.j,

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Image Sources, Licenses and ContributorsImage:Lipolybattery.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Lipolybattery.jpg  License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Kristoferb

Image:NASA Lithium Ion Polymer Battery.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:NASA_Lithium_Ion_Polymer_Battery.jpg  License: Public Domain Contributors:

Original uploader was JustinWick at en.wikipedia

Image:LiPo.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:LiPo.jpg  License: Public Domain Contributors: User:Achimd

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