I've noticed an odd trend in the lithium-ion batteries used in smartphones and tablets: rather than the 3.6V or 3.7V per cell typical of most Li-ion batteries in other types of consumer devices, they use 3.8V batteries that are charged to a maximum voltage of 4.35V (this is the case with both my Nexus 5X and Nexus 9). In at least one case (the LG G5 battery), the battery has a nominal voltage of 3.85V and is charged to 4.4V.
What's with these high-voltage Li-ion cells? I can understand that the higher voltage translates to more overall energy, but why pursue higher voltage instead of just higher capacity (as is done with 18650 cells)? Is there a drawback to using this type of battery?
A chat discussion starting here suggests that this higher voltage is specific to Li-poly batteries and does not apply to cylindrical cells like 18650 or prismatic cells like the sort used in compact camera batteries. Is this indeed the case?