BU-206: Lithium-polymer: Substance or Hype?

Find out why lithium-polymer is so popular.

The term polymer is commonly mentioned when describing a lithium-based battery, yet users cannot distinguish between regular Li-ion and a pack with the polymer architecture. Adding another battery type has little benefit and only confuses the market further. While the word “polymer” is perceived as a plastic, polymers range from synthetic plastics to natural biopolymers and proteins that form fundamental biological structures.

Lithium-polymer differs from other battery systems in the type of electrolyte used. The original polymer design dating back to the 1970s used a solid (dry) polymer electrolyte that resembles a plastic-like film. This insulator allows the exchange of ions (electrically charged atoms) and replaces the traditional porous separator that is soaked with electrolyte.

A solid polymer has poor conductivity at room temperature, and the battery must be heated to 60°C (140°F) and higher to enable current flow. Large polymer batteries for stationary applications were installed that needed heating, but these have since disappeared. The much anticipated hype of the “true plastic battery” promised in the early 2000s did not materialize as conductivity could not be attained at ambient temperature.

To make the modern Li-polymer battery conductive at room temperature, gelled electrolyte has been added. Most Li-ion polymer cells today incorporate a micro porous separator with some moisture. Li-polymer can be built on many systems, the likes of Li-cobalt, NMC, Li-phosphate and Li-manganese, and is not considered a unique battery chemistry. The majority of Li-polymer packs are cobalt based; other active material may also be added.

With gelled electrolyte added, what is the difference between a normal Li ion and Li ion polymer? As far as the user is concerned, lithium polymer is essentially the same as lithium-ion. Both systems use identical cathode and anode material and contain a similar amount of electrolyte.

Li-polymer is unique in that a micro porous electrolyte replaces the traditional porous separator. Li-polymer offers slightly higher specific energy and can be made thinner than conventional Li-ion, but the manufacturing cost is said to be higher than cylindrical design. For the purpose of discussion, pouch cells are often identified as being Li-polymer.

Li-polymer cells also come in a flexible foil-type case that resembles a food package. While a standard Li-ion needs a rigid case to press the electrodes together, Li-polymer uses laminated sheets that do not need compression. A foil-type enclosure reduces the weight by more than 20 percent over the classic hard shell. Thin film technology liberates the design as the battery can be made into any shape, fitting neatly into stylish mobile phones and tablet. Li-polymer can also be made very slim to resemble a credit card (See Pouch Cell.) Light weight and high specific power make Li-polymer the preferred choice for hobbyists.

Charge and discharge characteristics of Li-polymer are identical to other Li-ion systems and do not require a dedicated charger. Safety issues are also similar in that protection circuits are needed. Gas buildup during charge can cause some prismatic and pouch cells to swell, and equipment manufacturers must make allowances for expansion. Li-polymer in a foil package may be less durable than Li-ion in the cylindrical package.

Last Updated 2016-05-03

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On December 22, 2010 at 6:32pm
Lachlan wrote:

Do we have to wait until 2005 for a Li-polymer battery?

Perhaps this web page needs updating.

On January 6, 2011 at 9:44am
Ike wrote:

Lachlan, agree with you. Li-Po batteries come nowadays as standard in various products, such as new Nokia E Series phones… so it’s hardly “experimental” tech any more.

On January 27, 2011 at 11:51am
RIKK wrote:

li-pos are lighter than li-ion, it is a huge advantage in rc hobby.

On February 11, 2011 at 5:30pm
Ray Koosha wrote:

Li-Poly cells are aimed at minimizing the effect of swelling as compared to their Li-Ion counterparts.

On September 8, 2011 at 8:57am
Ken W. wrote:

Can you address the new (least least to me) LiFePO4 (Lithium Iron Phosphate) batteries. There does not appear to be any chargers available for these batteries. They can only be charged in the solar lights in which they are installed.

On October 3, 2011 at 2:36am
Andrew wrote:

Ken, LiFePO4 batteries can be charged with any constant current/constant voltage (CC/CV) power source like laboratory power sources. Just set the voltage to 3.6V and limit the current to something like 0.2C-1C (where C is cell capacity). As soon as current drops to 0.01C or less, it’s finished.

Also most contemporary RC chargers can charge LiFePO4.

On November 7, 2011 at 7:36am
Mark wrote:

“Also most contemporary RC chargers can charge LiFePO4.”


On January 23, 2012 at 3:23am
Pieter Borst wrote:

Is it right that Ion-polymere batterys has to be installed - saved or stored
in a certain position as some recomment -horizontal or vertical ??
I ask to excuse my “english”—I’m Dutch .
Grs Pieter.

On March 9, 2012 at 5:07am
Kevin Middleton wrote:

Think this site might need updating a bit,I’ve been using Li Po batteries in my model aircraft for years.

On April 11, 2012 at 6:13am
John Norman wrote:

I have to keep my llithium polymer batteries outside, and they could be there, unused for several months during winter.. Are they likely to be damaged when temperatures fall below zero???
The batteries are used for flying model aircraft.
Thank you

On May 27, 2012 at 4:48pm
Ron Xiu wrote:

Pieter Borst, lipo battery can use and store in any position. They are fully seal so electrolyte does not spill.

On May 30, 2012 at 11:25am
Dennis Staley wrote:

I’m new to LiPo (8 mos.) and have done all the research possible to get the most out of my new investments.  I use them in R/C aircraft, and have been very careful in the balancing-charging procedure.  Each of my four 3-cell (11.1V) packs have been used carefully and not discharged below 40% of capacity (11.43V).  However, all four packs have gradually increased in “puffiness”, which occurs during flight and not during charging.  The packs are always moderately cool to the touch after flying and charging, but the puffiness seems to increase regardless.  The manufacturer (Park Zone) states they should be discarded when puffiness occurs, but the hobby shop manager says they are just fine, and compared to the ones HE uses, their puffiness is minimal.  His will almost ROLL down a slight incline!  He also flies his batteries until there is a reduction in available power, while I time my flights and land BEFORE the voltage is below the 40% recommended minimum.  I’ve not seen any “technical” information or advice on this phenomenon, and would welcome knowledgeable opinions.

On June 6, 2012 at 5:55pm
sunnyzeng wrote:

LiPo batteries will share a larger market share in future, and will be widely used on differents kinds of difital products. we are li-ion and liPo batteries manufacturer,and at present we are develop liPo battery market

On June 9, 2012 at 9:19am
Dennis Staley wrote:

I was notified that sunnyzeng had entered a response to my question regarding LiPo packs expanding (puffing out) because of expanding gas leaking from the cells.  Does sunnyzeng mean his company is “developing LiPo battery market” by making the batteries with a short life span and therefore a built-in obsolescence?
Let me make my question more to-the-point:  What degree (or measurement) of “puffiness” makes a LiPo pack dangerous for continued use?

On October 10, 2012 at 6:37am
Srinivas Raj.G wrote:

What are the Layers of Lithium ion and Applications ?

On February 18, 2013 at 3:28pm
Paul Vigushin wrote:

I am looking for an expert in LiPo batteries to consult with on a fire claim.  Please send e-mail to paul@pv-law.com.

On April 3, 2013 at 9:46pm
Ariyan wrote:

poor me, my limited brain still couldn’t decide that Li-Po is substance or just hype? my temporary conclusion is, Li-Po is made to replace Li-ion, because it has same energy with Li-ion but Li-po is lighter, smaller (or can be made in small form), but it’s poor conductivity made Li-Po easy to hot than Li-Ion that’s why it needs a gel to cool it, but it made Li-Po more fragile becuase it’s gel can be change to other form (or puffiness like Denis Staley above said) if the battry is dropped, or hard pressed, so that’s why many phone manufacture still use Li-Ion battery, because Li-ion still more efficient and economical than Li-Po, my new BlackBerry Z10 is one of them.. CMIIW (sorry for my poor english i’m Indonesian)

On April 22, 2013 at 8:35pm
Hari wrote:

Guys I need some basic knowledge . help me

I bought a smartphone last week and it is written “Polymer Battery” on the battery
You can view the image of battery in below links:



But whenever i typed ” polymer battery” in google, the results brought only about lithium polymer battery ....(including this site)
I can’t find a single site which speaks about polymer battery ,, everywhere it is Lithium Polymer ..

So my doubt is , Are polymer battery and lithium polymer battery same ?

Is the term POLYMER BATTERY is another name to mention lithium Polymer (LiPo) battery ? OR Both lithium Polymer and Polymer battery are Different ?

On May 2, 2013 at 3:19pm
Mads wrote:

“Charge and discharge characteristics of Li-polymer are identical to other Li-ion systems and do not require a special charger”

Needs to be precizes that there’s no need for separate charger exactly between Li-Ion and LiPo batteries. smile
At first time reading this it makes a sense as if LiPos can be charged with NiCd battery charger also, which is extremely dangerous attempt.

On June 16, 2013 at 11:24am
matt wrote:

I wanted to answer Hary’s question. I’m not 100% sure but I’d say I’m 95% sure that the batteries you bought are LiPo’s.
Whoever wrote simply: Polymer battery, did so because he/she thought it sufficient because consumers that pay attention to that type of thing would know what they were getting. Also, who know’s? Maybe he/she figured it would be obvious since there’s no such thing as a polymer battery.

On July 26, 2013 at 12:34am
Michael wrote:

Is it possible to use multiple 12v Li-polymer car starter batteries in series (total 72V) in a continuous duty cycle, such as an electric propulsion system without overheating?

On October 28, 2013 at 2:02am
randy wrote:

it seems common to have prismatic/polymer in parallel configuration. but, is it common to put them in series? or how about series and parallel combination?
is there a reason why there are more cylindrical Li-ion batteries in series than Li-ion Polymer in series?


On November 23, 2013 at 6:47pm
Heiko wrote:

A friend of mine is an rc model car racer and he says LiPo batteries are a blessing. 15 years ago they were having problems with just a standard racing distance of 20 rounds (I believe, sorry if I’m wrong) while nowadays with LiPo batteries they could go for the double distance, if they wanted.
Batteries used to be the one weak link in rc racing, but with LiPo batteries all that went away and the models could theoretically have more power than what you can actually get down on the street.

On February 19, 2014 at 11:32pm
nishant sharma wrote:


On June 2, 2014 at 2:29am
Ramakrishna Rao wrote:

Can Li-Po batteries be taper charged? I.e. charge a 1000 mAH battery at 250 mA when 6.2V, 120 mA at 7.4V and 50 mA at 8.0 volt and stop charging at 8.4V

On June 28, 2014 at 8:19am
Ray wrote:

Ramakrishna Roa, yes my charger does it.

On July 20, 2014 at 11:06pm
Gary wrote:

I have noticed my lipo batteries seem to take twice as long to charge once the temperature drops to single figures. I use then in an RC model they last about ten minutes but take and hour and a half to charge.

On August 22, 2014 at 10:41pm
dave . M wrote:

To whom ever is in charge of this website ; do you know that there is an advertisement of pornographic material on the right of your website with a very dirty pictures of Gay porn?

Is this what you get paid for? ,. it may O.K for you but you should consider the reality that some people might find it disturbing !?!.

Dave Manning

On August 29, 2014 at 2:46am
Prachi Agrawal wrote:

Could you provide a comparison between solid state lithium-ion batteries and standard lithium-ion batteries that have a liquid electrolyte?

On October 29, 2014 at 12:21pm
Kathleen O'Connor wrote:

New personal vaping tech is pushing battery capabilities.

I’m still looking for current data on the progression of the Li-Po’s for use in personal vaping devices. Claims of better performance and of course flexibility of shape area big plus. What else should I know; what milestone should I wait for.

Example: http://www.sourcingelectricals.com/3-7V1850mAh-li-polymer-battery-10113003/

On January 16, 2015 at 5:37pm
Jon D wrote:

Does anyone have experience with potting lipo batteries with a foil type pouch?  I know swelling during charging and discharging can be an issue, but first encasing the battery in a compressible material would mitigate that.  Otherwise, are there any other safety concerns or techniques that might help?

On January 19, 2015 at 2:16pm
Gerard Campeau wrote:

We have an application for a Battery in an most high temperature Environment . 90% humidity and 100F to 140 F . 12V at 2 Ah can anybody suggest the best and most economic battery and source. Qty about 200to 2000 units to start.

On February 28, 2015 at 2:28pm
Shelli wrote:

I’m looking for a replacement battery for my MacBook Pro, and am faced with the decision regarding lithium-ion, or Li-Po.  The prior battery got very warm, and finally puffed out, so I’m a little confused, do the Li-Po’s run cooler?  Or warmer?

Oh, and Dave Manning:  Ever heard of “clickstream data?”

On June 25, 2015 at 1:39pm
Barney wrote:

To echo the concern of a previous post.  Can Lion be charged on a charger designed R/C hobby Lipo?  Charger balances and charges to 4.20V/cell.

On August 25, 2015 at 12:03pm
Shaurya sheth wrote:

Does Lifepi4 battery comes under lipo battery category?

On October 27, 2015 at 6:27am
Jon Powell wrote:

I only “know” what I read, which means I know nothing. Repeating to myself what I read only means I can remember some stuff.  Confusion reigns with all the various sellers/makers self serving hype. What’s true?? The learning curve is steep, perhaps long. I need a starting battery with a reasonable price/value/service life ratio that I can move from forklift to tractor to car to lawnmower easily. Some equipment is seldom used so I don’t mind moving the battery about. Please make a recommendation for brand and if possible a model. Wonderful website, great expertise. Thanks, Jon Powell

On January 22, 2016 at 3:38pm
Paul Burnett wrote:

Is there a lot of energy loss between batteries? i have a solar charger with a 5000mah Li-polymer battery and when fully charged will not 100% charge my phone which has a 2600mah capacity battery

On March 11, 2016 at 2:22am
Philipp B wrote:

@Jon Powell: Have a look at Super B products. These are high quality, easy to use battery packs and they offer various sizes that could serve your needs. They have built in safety circuits and temperature control.

On April 15, 2016 at 6:19am
Steve_B wrote:

@Paul Burnett: You have to also consider voltage along with mAh capacity. If for instance your 5000mAh battery is a 1s (3.7V) type then it has less stored energy than a 2s (7.4V) 2600mAh pack and would therefore be incapable of fully charging it.
The energy stored is a battery is most conveniently measured in ‘Watt-hours’ which is nominal voltage multiplied by Amp-hours.

On June 29, 2016 at 7:51pm
KP wrote:

I am having a hard time finding good information on what is the difference between you standard 1C discharge rate lipo battery and the high discharge (up to 50C) rate lipo batteries that are marketed for RC cars. What is the difference in the construction or materials used to allow for this high discharge rate? Do the higher C rated batteries have a shorter lifetime (number of charge cycles)?

On July 29, 2016 at 3:05am
Mighty Raskal wrote:

i need help in choosing right battery for my application!
my application is Emergency LED light, constant load of 10V and 1.68Amps.
i need a cheap and good performance battery,
which one is better, Lipo or Lion?

On August 2, 2016 at 9:39pm
Chris Barth wrote:

KP, High rate discharge lipos have thicker copper layers that are able to handle more current with less heat.  More copper does make that cells heavier.

On August 7, 2016 at 7:36pm
Achuthan Nedunghat wrote:

I wish to use Li-polymert battery of about 40,000 mA capasity at about 14 to 15 volts
for one of the portable application we had designed. We have used Ni-cad battery( since it was easily available and battery research was not the core interest at that point of time) pack of the similar capacity. The electronic system is working satisfactorily.

Now that system is working well we wished to replace the battery either with Li-ion or
with the Li-polymer. It will be very kind of you if one could educate me with
1. details like charging discharging characteristics
2. enegy density when compared with Nicad
3. durablity considerations

My name is Achuthan, an Electrical Engineer by profession with MS ( by reseach) from IITM, chennai, India.www.presevi.in is our website.

On September 27, 2016 at 4:41am
Vishwa Vasani wrote:

I read somewhere that LiPo cells must be packed while applying some pressure on the faces, because during charge-discharge cycles, they puff up, and as a result, the contact between different layers inside the cell comes slightly loose, increasing the internal resistance. On the other hand, this article suggests that manufacturers must make allowances for this ‘swelling up’ in their design. Which of these is correct?

On October 9, 2016 at 9:55am
John wrote:

What happens if the battery package swells and the gas leaks out?  I had to disconnect and reconnect the lithium battery on my Nook, and when I was putting it back together, the battery package popped and a gas leaked out.  There is now a hole in the battery package.  The device is working fine for the moment.  Will the hole in the battery package be a problem? 


On November 13, 2016 at 11:59pm
Bhanu Konikki wrote:

Hello ,
I’m using LiPo battery of 3,500 man in my mobile.
While charging, it automatically heats up(I don’t use mobile while charging).
Why it happens?
What I have to do to solve this problem?
What is the safe zone to charge my mobile like 0 - 100% or 20-80%?