Charging li-po battery with phone charger
You need a LiPo battery charger. Connecting the battery directly to the phone charger will if you're lucky do nothing. If you're unlucky it will make your battery do an impression of a Samsung Note 7.

A phone charger is very inaccurately named, all it does is supply a constant 5V. All of the intelligence in how to charge the battery is built into the phone itself.