Confused on Lithium-Ion Batteries to Output 5V 4.4A for a Project
If you want a battery-powered 5v, then your best bet is to get a 5v 'power pack', which contains both a built-in conversion to 5v, and a charger for the internal batteries.

Make sure its capacity is rated at the 5v output, when deciding whether it will power your load for sufficient time. Some naughty ones rate the charge capacity of their internal 3.7v battery, which will be less by the time it's been converted to 5v.