Modern phones and tablets come with different types and sizes of batteries. The most common battery types used in modern phones is the Lithium Ion and Lithium Polymer batteries.
Lithium Ion (Li-Ion) Batteries
This is the older and most popular technology for cell phone batteries. Lithium Ion batteries have a higher energy density compared to the lithium polymer battery. However, they are expensive compared to the latter.
Lithium Polymer (Li-Poly) Batteries
Lithium polymer batteries are more technologically advanced compared to lithium ion batteries. These batteries are ultra lightweight and generally deliver more than forty percent more capacity than other batteries. Another advantage of this type of batteries is that they do not suffer from the "memory effect".The "Memory effect" is a phrase used to describe a situation when a battery is not fully charged and therefore during the next charge cycle, the battery will recall the shortened charge cycle. This reduces the battery capacity and therefore reduces battery life as well.
Both Li-ion and Li-Poly batteries have the same chemical composition but the difference lies in their tendency to overheat. To prevent overheating, Lithium Ion batteries have an active protection circuit that prevents it from overheating and potentially exploding. On the other hand, Lithium polymer batteries do not need the active protection circuit. This is why they can be manufactured in sizes as tiny as a credit card.
Another criteria to classify batteries is its usage patter: replaceable and non-replaceable.