Power banks: Li-ion vs Li-poly?

I’m looking to purchase a good quality power bank in the 20k range. I think safety would be my biggest priority. How do both types of batteries compare to one another?

Li poly can be fit into a smaller space and have an higher amp output but lower energy density,

Li ion have higher energy density but lower amp output and of course are cylindrical so take up more space.

Check out some of HKJ extensive tests.

For a power bank for mobile charging etc, li ion is fine.

Anker are one option, a bit more expensive but top quality cells. Blitzwolf are another good manufacturer of power banks, should be cheaper. HKJ has already reviewed some from both manufacturers

Uh, no…
Lithium Polymer is a type of lithium ion battery.
They both can be in any shape or size.

+1 on the Anker packs. I have a 20,000mah unit and it has been great. 3x2.4A output and dual parallel fast charging inputs.

Both Anker and BlitzWolf are excellent choices.
Check out HKJ:s reviews, it’s the best source of information.
Also note that there are units that lets you use your own choice of cells, typically 18650:s.

I think you mean 18650-based vs LiPo-based powerbanks.

In my testing, LiPo powerbanks usually perform a little bit better than theit 18650-based counterparts.
If you'd like to see the data, click the bottom left link in my sig.

But, LiPo packs are a little more volatile when something goes wrong, most reputable brands use reputable 18650's which fail in a more controlled way.

At least, that's my experience, based a lot on the tests mooch runs.

The Li-poly power bank is more light weight than Li-ion. And Li-poly battery has a stability that is safety. Tattu lipo power bank is great to choose.

While 18650-cells include several safety measures (depending on manufacturer/model), LiPo-batteries dont.


Get a case for 18650 cells and choose high quality protected cells with PCB from an brand with best reputation.


Enerpower is “Assembled in Germany”, Keepower, Nitecore and Fenix are well too.

Per what I have read the multiple 18650 Install Your Own Battery power banks recommend UNPROTECTED cells as the bank, if a decent one, has it’s own protection circuitry for the cells. Also many such power banks have limited length battery holder slots. My 4 cell Soshine certainly does.

Are there any power banks suitable for LiFePO4 cells?
Is there any dedicated charger that defaults to the proper voltage for recharging LiFePO4 cells?

Here’s why I like them:

I find I’m accumulating older flashlights that I’d like to give away to family members, but only if I can give them with these safer cells like these:

EDIT: HJK has the info I was looking for about chargers:

Modern Li-Ion cylindrical cells are safe enough to compare against LiFePo4 in normal using conditions. You’d have to physically damage a powerbank in order short it, otherwise it is well protected from over charging and over temperature.

Pouch cells or Polymer packs can achieve higher density inside a squared case than 18650, but over time they will swell if left fully charged and not being cycled for long periods of time. It is also more sensitive to temperature changes and over charging.

I had to get rid of my xiaomi 20,000mAh gen2 which uses 2x10,000mAh pouch cell because of this. The unit was working perfectly with little loss of capacity, but had swollen to the point of being dangerous to carry around. The old one which is almost 4 years old now is still going strong, that one uses 6x18650 3350mAh.

usually power banks have 18650s under the hood

They are just too common to not use

car jump starters are a different story, they usually use rectangular li iron phospate for safety


I ended up buying a couple of these from Illumn
(though they shipped only one of them, so someone’s likely asleep in their shipping department)

Xtar PB2S QC 3.0 + PD 3.0 Portable Li-ion Charger and Powerbank
They take 21700 unprotected cells, which I also bought, and Illumn assured me this powerbank has overcharge/discharge protection.

As others have noted above, the round cells seem more reliable than anything with flat-bag cells.

I’ve had one of those flat cells balloon, in a cheap little powerbank, in my own experience, and I find self-disassembling batteries scary.

the ballooning is sort of a safety feature
after they do that, the impedance rises so that shorts cannot cause overheating
if it is a car jump starter thing, usually they will no longer start a car
i tested one of them once at 200A on a battery tester at work, it smoked, insulation melted and it quit working
took it apart and 1 or 2 of the flat cells had swelled up
max current was then about 5-10 A


How did you decide?

Lithium-ion technology is currently the best performing technology for energy storage based on batteries. Li-ion batteries are used in small electronics (smartphones, laptops) and are also the best options for electric cars.

  1. Very high energy density, with potential for even greater density in the future.
  1. Prolonged charging of new batteries not required.
  1. Low discharge rate equivalent to half that of nickel-based batteries.
  1. Low maintenance requirements – period discharge not required.
  1. Can be configured to provide very high current to applications such as power tools.

Why would a Polymer pack swell over a Li-on. I thought both were built with similar chemicals.

Well, unless you are on the bleeding edge, the same chemistry is being used between lithium-ion cylindrical cells and pouch cells.

And @agent80, the main difference is due to how differently pouch cells are built, they are much more fragile, and can gas off much more easily.

Very imformative. Thanks