Datasheet

You may be asking then, How come adafruit sells battery packs that are paralleled?

These two packs are clearly two and three batteries. Since they are 3.7V they must be in parallel. Isnt this unsafe?

The answer is that these batteries are assembled by a company that is experienced and certified to test and assemble

battery packs. The individual batteries are tested and sorted by machine so that each pack has matching batteries with

the same capacity and internal resistance. Individuals do not have this equipment, which is why you should not try to

make your own packs.

So the next question is whether you can connect batteries in series to get higher voltages?