Which power bank is good, lithium ion or lithium polymer?



Both are similar and good for different reasons but ultimately, cost and functionality appear to be the key determinants of preference.

Difference between Li-ion vs Li-Po
Lithium ion (Li-ion) - Gives high energy density, low discharge rate, no special preparation or charging required before first use and overall cost is comparatively cheap. However, they suffer from aging even when not used. You may have heard of battery life cycles, 500 cycles, etc. The battery packs tend to have an internal control circuit that regulates current to prevent overheating or explosion. The result is you get long life battery packs.


Li-ion batteries are normally encased in hard packs and also don’t like cold temperatures. To ensure best performance, use/charge in fairly warm room temperature. They are easy to modify and the high energy density attracts lots of investments for innovation, safety advancements, versatility of usage like in electric cars, etc.

Health & Safety issue – high risk of explosion if charged too quickly or inappropriately. You may remember Samsung Galaxy Note 7 explosions and product recall in 2016. The smartphone was packed with 3,500mAh lithium-ion battery.

Samsung's President DJ Koh, said in a conference in Seoul, South Korea that the problem was caused by negative electrode components which deflated and caused short circuit that resulted in overheating and explosions. 

As a result of these problems, testing standards are very stringent.

Lithium-Polymer (LiPo) – This may appear to be a marketing gimmick but the primary difference is that rather than liquid lithium electrolyte, it uses solid but flexible polymer electrolyte. This means that thin and lightweight designs can hold slightly higher specific energy hence good battery life and, with lower energy density, it is comparatively much safer that Li-ion. But the lower energy density also means it is more expensive to produce. 



This means that this type of battery pack may look sleek but you won’t get as much power from it compared to a li-ion battery pack. If battery cells are faulty the battery pack can also suffer from high temperatures, overheat and expand as seen in Apple iPhone 3GS. These may smoke but not explode given the low energy density of this type of battery.


The Implication
To cut costs and make their products more affordable, a significant number of manufacturers mostly go for lithium–ion. Many gadgets like power banks, smartphones, laptops, tablets, ebook readers, MP3/4 players, cordless devices, etc. are made with lithium-ion battery cells which normally have a voltage rating of 3.7v. 

Some gadgets do come with Li-po battery packs backs which give the added benefit of being able to increase voltage by adding more cells to a flexible plastic container battery pack. 

When you add a circuit breaker or internal circuit control unit to monitor performance temperature, input/output power, charge level, etc, (to ensure they don’t explode) you technically have a power bank.

Health & Safety concerns
All battery types are susceptible to different levels of risk of fire/explosion due to the inherent nature of electric current. With this in mind, HetoGrow’s solar power banks are built with double overcharge and discharge protection. This is very important for regions with voltage volatility. For more info about this risk see - Can a Power bank explode itself, without any triggering factor?

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