The Next Notebook Battery? Lithium Polymer

Lewis Clarke writes "Sony is changing its course to use an old technology for its new battery manufacturing. ZDNet is reporting on comments from Sony Electronics President Stan Glasgow, where he said that Notebook makers will 'likely' soon choose to incorporate lithium polymer batteries (a battery technology that emerged nine years ago) over the current commonly used type, lithium ion batteries." From the article: "Lithium polymer batteries use lithium as an active ingredient. Lithium is a volatile material, but the lithium in these batteries isn't packed into cells as it is in lithium ion batteries. Instead, it is contained in a polymer gel. These gel batteries can't provide the same sort of energy density as lithium ion batteries, but that's now a plus."

Lithium Polymer is already in use

[syncrotic]

High end notebooks from Dell, IBM, and possibly others all use lithium polymer batteries for their drivebay batteries, where space is extremely tight and the geometry is suboptimal for cylindrical cells. Li-polymer batteries can be made into very thin shapes and don't need a metal case to contain individual cells. Because of this, the energy density is actually higher. I think the reason they're not in widespread use is simply that they cost more.

Next Notebook Battery?

[bill_mcgonigle]

You mean "current notebook battery"?

I'm typing this on a c2d MacBook Pro [apple.com] which lists a lithium polymer battery as its spec. Third bullet line down on that page. I also have a 5GB iPod that uses a lithium polymer battery [apple.com]. Apple went Li-Ion for later iPods, probably for higher capactiy, but I'm on my second battery in 5 years and it gives me more than 8 hours of playtime (haven't tested it beyond that).

I guess that means Apple isn't using Sony for its current batteries?

Re:Eh?

[arth1]

I must be getting confused - I thought Lithium Polymer was better than Lithium Ion?

In some ways. It's the same thing, really, but packaged two different ways. Both are often called Li-Ion batteries, cause they are. The main two advantages of Lithium Polymer are:
(A) They can be shaped in all kinds of odd shapes, which is a benefit when you also pack some circuitry inside the battery package, or have to use space as best you can.
(B) They are less likely to explode, as there's resistance in the gel medium itself that hinders (if not completely prevents) a chain reaction.

The main downside to Li-Polymer is that it is less efficient by volume and weight.

Regards,
--
*Art

Be VERY careful

[IflyRC]

As my name implies I fly R/C aircraft as a hobby. Within the last few years electric powered models have really taken off. Most of this is due to the Li-Po battery. Lithium Polymer batteries are a subset of Lithium Ion batteries but the design of the cells are different.

Li-Po batteries are small and light and can produce a higher continue current than lithium ion. They are very powerful batteries.

One of the problems though...and why I generally stay away from them is that they explode. They can easily become unstable if dropped (or crashed). I don't claim to be an expert but the cells in a lithium ion battery are metal - they can sustain an impact and vibration where as the cells in a lithium polymer are mostly plastic which can cause a mix of the chemicals inside and cause the battery to heat up until it vents and then explodes.

Fire caused by overcharging [rcgroups.com]

Video of a lipo battery going bad. [helihobby.com]

Not sure about the weight thing.

[Kadin2048]

The main downside to Li-Polymer is that it is less efficient by volume and weight.

This, I think, is not true. LiIons may be more efficient by volume, but LiPos are almost certainly more efficient per weight, because they don't have the cells, or many of the protection mechanisms that LiIon batteries have to have.

The power/weight advantage is why they're used in applications where weight is more important than volume -- R/C aircraft, for instance. When LiPo batteries came out, they basically replaced NiCads and LiIon batteries overnight in most ultralight aircraft and helis, because they're just so much lighter (meaning that if you had an aircraft designed for NiCads, which wasn't atypical, you could get ridiculous flight time by upgrading to LiPoly cells).

But being more efficient per volume, that I could definitely believe.

The other big advantage I have heard is that with LiPo, you don't have to encase the batteries as heavily, so more of the weight and volume can actually be taken up with electricity-storing components, instead of as an 'exoskeleton' providing protection for the cells.

Re:lifetime?

[Rob the Bold]

has anything changed with this or is what i've heard BS?

You can design in a larger and more costly charger manager in a notebook battery than you can in a digital audio player. More sophisticated charge management ICs have dead battery precharging cycles, thermimstor inputs to watch cell temp, and smarter logic for charging battery depending on state of charge when you plug it in to the charger. The smaller, low cost chargers you use for small electronics aren't nearly so smart, most just stop charging at a given voltage (or at the end of the safety timeout).

Anyway, you can get better battery lifetime if you can afford the cost and size of a fancier charger. Doesn't mean the guys designing small devices are doing a bad job, they just have a different tradeoff to make when doing the design.

Already used in laptops

[sith]

The 17" powerbook G4 and all the macbooks and macbook pros use LiPoly batteries. So does the iPod. (Notice that the Sony recall was only for 15" and 12" powerbook g4s)

Re:Lithium Polymer is already in use

[edmudama]

exactly.

Energy density of the raw charge storing material is lower with LiPo, but it doesn't require the same packaging/metal casing, so net energy density is higher.

Something like 2.5 times as much power per weight as Li-Ion battery packs. It's revolutionized RC electrics.

Models that were designed for NiMH cells and were getting 4-5 minutes of flight time, can now get 15 or more minutes of flight.

Heavy, Man.

[tryptych]

I use Lithium Polymer batteries in my SLR camera. It's a whacking great lump that bolts on the bottom, and although it's way better than conventional AA's (even NiMH), they are hellishy expensive ($300-£400), and they are bloody heavy! One further factor is it's a typical Sony ploy. Invent a totally unique accessory that only Sony make, and charge three times the price for it. (ie, $10 power supplies with an oddball connector they sell for £150) That's why I wont buy anything from those people.

Re:NOT TRUE

[IflyRC]

True, its not a forceful explosion but the flames are so intense it wouldn't really matter (without the danger of shrapnel). NiMH and Nicad can explode as well but it takes a lot to get them to that point - usually overcharging. Lipos can go just from being dropped.

How many laptops do you see being dropped? Apparently there is enough lap top dropping that IBM was advertising how sturdy their laptops were a few years back.

Re:Polymer is safer

[IflyRC]

I'll fly my small foam electric plane with a Li-po 1500 mah 11.4 volt battery for 15 minutes. Tell me if the battery isn't hot ;) Trust me, it gets hot and you cannot re-charge these things until the battery cools down.

Dilithium won't supply you any power!

[freeze128]

Dilithium is just a catalyst for the matter/antimatter reaction. You would still need a supply of matter, and antimatter, and containment, which would add way too much to the weight for your puny earth laptop.

In TNG, all their hand-held and portable devices use Sarium-Krellide power cells.

Re:Not sure about the weight thing.

[araemo]

The advantage to custom designed LiPoly batteries is that you can pack them into tons of nooks and crannies. The thing that still amazes me about your average laptop is that inside that fancy plastic battery pack is a row of cylindrical batteries with air around them. Lipoly fills in all that air with one solid mass of battery, so while the literal energy storing material may be less volume efficient, you can make more efficient use of volume in your designs as opposed to standard LiIon.

All MacBook Pros/MacBooks use LiPo

[ModernGeek]

All of Apples MacBooks and MacBook Pros have used LiPo since their debut in January. That's why battery life was uncertain, because LiPo had not been used in notebooks before. I hear they are supposed to be better than LiIon.

Lithium is NOT volatile

[jpetts]

Lithium is a metal with a melting point of 453.69 F and a boiling point of 1615F. It is a REACTIVE metal (being one of the alkali metals), but it is definitely not volatile.

Re:Be VERY careful

[bughunter]

My job is building hi-rel batteries for launch vehicles and spacecraft, so let me share some facts that seem to be in confusion in this forum.

First, The distinction of Li-Poly from the general chemistry of Li-Ion is in the electrolyte. Instead of a liquid or gel electrolyte, the Li-Poly cell uses a thin sheet of conductive polymer doped with ionic compounds. Now while this polymer electrolyte has less mobility than a liquid, resulting in a lower energy density (J/cm^3) and power density (W/cm^3), in practice the manufactured shapes can be more complex than the coin or cylindrical shapes imposed by liquid electrolytes. Therefore more "battery cell" can be stuffed into otherwise unused volumes, and in many applications this maximizes the effective energy density beyond what can be achieved using cylindrical cells.

Second, any Lithium chemistry cell using a Cobalt-alloy cathode (virtually all of them on the market today) is subject to a thermal runaway condition if the internal cell temperature exceeds 130C. This includes Li-Poly cells.

Valence corp has patented a Lithium-Iron-Phosphate cathode chemistry that has less energy density, similar to NiCd, however the change to a Iron cathode eliminates the thermal runaway possiblity, making the cells much safer. These will soon be available commercially from DeWalt as battery packs for their cordless power tools. Here [dewalt.com] is a press release... note that Valence later bought the company referenced therein, A123 Systems. (I wonder if there's been a delay somewhere - DeWalt was marketing this much more heavily just a few months ago, now you have to do a search on their site to find any reference of it.)

Another company, Altair Nanotechnologies, has patented a Litium Titanate Spinel anode technology that also claims to eliminate the risk of fire and improve on both the Energy Density and Power Density of vanilla Li-Ion. However they have yet to actually deliver cells (to me anyway, despite many requests). And this chemistry is not exclusive to the Iron Phosphate cathode, meaning someone with all of the proper patent licenses could combine the two and make a high energy-density, non-exploding laptop battery that does even better than the Li-Poly battery I'm using in my MacBook Pro right now.

Finally, here's a link [batteryuniversity.com] to the "Safety Concerns" page of the "Battery University" site which is an excellent user's reference for Li-Ion secondary batteries, among others. And here is a link [valence.com] to a Valence Corp white paper that describes their LIP cells. Lastly, here is a PDF [altairnano.com] of Altair Nano's marketing material describing their claims of safety advantages their Titanium spinel material offers to commercial batteries.

Re:Not sure about the weight thing.

[sporkme]

Most laptop battery packs are comprised of lithium ion cell #18650. They are 3.6 volts (some denote them as 3.7 volts) each cell and are typically around 2200 mAH (2.2 Ampre-Hours). They are arranged in series-parallel to achieve the desired voltage (~14.4 volts) and capacity (~4400mAH).

Lithium polymer offers a lighter package at a higher volume to achieve the same capacity and discharge current. Because of the high resistance characteristics of the polymer-only substrate, some liquid electrolyte (the stuff used in lithium-ion cells) is is added for consumer electronics applications. It gels with the polymer. The polymer alone is not much of a fire risk, but with the addition of its cousin's more volatile electrolyte, that risk has developed. The attractive feature of li-poly is that you can fill all the voids in a device with battery mass, and that it does not usually create as much heat when charging or discharging.

Notably, lithium polymer has a lower cycle life than lithium ion typically does -- that is it will survive fewer charges/discharges.

At least we aren't hauling around giant sealed lead acid batteries (like in a UPS or alarm system) everywhere.